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Sökning: WFRF:(Arner Peter)

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1.
  • Arner, Peter, et al. (författare)
  • Dynamics of human adipose lipid turnover in health and metabolic disease
  • 2011
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 478:7367, s. 110-113
  • Tidskriftsartikel (refereegranskat)abstract
    • Adipose tissue mass is determined by the storage and removal of triglycerides in adipocytes(1). Little is known, however, about adipose lipid turnover in humans in health and pathology. To study this in vivo, here we determined lipid age by measuring (14)C derived from above ground nuclear bomb tests in adipocyte lipids. We report that during the average ten-year lifespan of human adipocytes, triglycerides are renewed six times. Lipid age is independent of adipocyte size, is very stable across a wide range of adult ages and does not differ between genders. Adipocyte lipid turnover, however, is strongly related to conditions with disturbed lipid metabolism. In obesity, triglyceride removal rate (lipolysis followed by oxidation) is decreased and the amount of triglycerides stored each year is increased. In contrast, both lipid removal and storage rates are decreased in non-obese patients diagnosed with the most common hereditary form of dyslipidaemia, familial combined hyperlipidaemia. Lipid removal rate is positively correlated with the capacity of adipocytes to break down triglycerides, as assessed through lipolysis, and is inversely related to insulin resistance. Our data support a mechanism in which adipocyte lipid storage and removal have different roles in health and pathology. High storage but low triglyceride removal promotes fat tissue accumulation and obesity. Reduction of both triglyceride storage and removal decreases lipid shunting through adipose tissue and thus promotes dyslipidaemia. We identify adipocyte lipid turnover as a novel target for prevention and treatment of metabolic disease.
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2.
  • Arner, Erik, et al. (författare)
  • Adipocyte Turnover : Relevance to Human Adipose Tissue Morphology
  • 2010
  • Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 59:1, s. 105-109
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE-Adipose tissue may contain few large adipocytes (hypertrophy) or many small adipocytes (hyperplasia). We investigated factors of putative importance for adipose tissue morphology. RESEARCH DESIGN AND METHODS-Subcutaneous adipocyte size and total fat mass were compared in 764 subjects with BMI 18-60 kg/m(2). A morphology value was defined as tire difference between the measured adipocyte volume and the expected volume given by a curved-line fit for a given body fat mass and was related to insulin values. In 35 subjects, in vivo adipocyte turnover was measured by exploiting incorporation of atmospheric C-14 into DNA. RESULTS-Occurrence of hyperplasia (negative morphology value) or hypertrophy (positive morphology value) was independent of sex and body weight but con-elated with fasting plasma insulin levels and insulin sensitivity, independent of adipocyte volume (beta-coefficient = 0.3, P < 0.0001). Total adipocyte number and morphology were negatively related (r = -0.66); i.e., the total adipocyte number was greatest in pronounced hyperplasia and smallest in pronounced hypertrophy. The absolute number of new adipocytes generated each year was 70% lower (P < 0.001) in hypertrophy than in hyperplasia, and individual values for adipocyte generation and morphology were strongly related (r = 0.7, P < 0.001). The relative death rate (similar to 10% per year) or mean age of adipocytes (similar to 10 years) was not correlated with morphology. CONCLUSIONS-Adipose tissue morphology correlates with insulin measures and is linked to the total adipocyte number independently of sex and body fat level. Low generation rates of adipocytes associate with adipose tissue hypertrophy, whereas high generation rates associate with adipose hyperplasia. Diabetes 59:105-109, 2010
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3.
  • Arner, P., et al. (författare)
  • Circulating Carnosine Dipeptidase 1 associates with weight loss and poor prognosis in gastrointestinal cancer
  • 2015
  • Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Cancer cachexia (CC) is linked to poor prognosis. Although the mechanisms promoting this condition are not known, several circulating proteins have been proposed to contribute. We analyzed the plasma proteome in cancer subjects in order to identify factors associated with cachexia. Design/Subjects: Plasma was obtained from a screening cohort of 59 patients, newly diagnosed with suspected gastrointestinal cancer, with (n = 32) or without (n = 27) cachexia. Samples were subjected to proteomic profiling using 760 antibodies (targeting 698 individual proteins) from the Human Protein Atlas project. The main findings were validated in a cohort of 93 patients with verified and advanced pancreas cancer. Results: Only six proteins displayed differential plasma levels in the screening cohort. Among these, Carnosine Dipeptidase 1 (CNDP1) was confirmed by sandwich immunoassay to be lower in CC (p = 0.008). In both cohorts, low CNDP1 levels were associated with markers of poor prognosis including weight loss, malnutrition, lipid breakdown, low circulating albumin/IGF1 levels and poor quality of life. Eleven of the subjects in the discovery cohort were finally diagnosed with non-malignant disease but omitting these subjects from the analyses did not have any major influence on the results. Conclusions: In gastrointestinal cancer, reduced plasma levels of CNDP1 associate with signs of catabolism and poor outcome. These results, together with recently published data demonstrating lower circulating CNDP1 in subjects with glioblastoma and metastatic prostate cancer, suggest that CNDP1 may constitute a marker of aggressive cancer and CC.
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4.
  • Arner, Peter, et al. (författare)
  • Variations in the size of the major omentum are primarily determined by fat cell number
  • 2013
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 98:5, s. E897-E901
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: Accumulation of visceral adipose tissue (VAT) is strongly linked to insulin resistance. Variations in the size of any adipose depot are determined by alterations in adipocyte volume and/or number. The individual contribution of each of the latter factors was determined in the major omentum, a fully resectable VAT depot.SUBJECTS: Total removal of the major omentum (omentectomy) was performed in conjunction with bariatric surgery in 55 obese patients. Tissue weight as well as mean adipocyte size and number in the omentum were determined. In subgroups, total VAT was estimated by computerized tomography (n = 17) or dual-energy x-ray absorptiometry (n = 34).RESULTS: The weight of the major omentum (on average 0.6 kg) correlated significantly with total VAT mass estimated by computerized tomography or dual-energy x-ray absorptiometry (r = 0.48-0.7; P < .01). Omental weight in relation to total body fat correlated with several features of the metabolic syndrome and inversely with serum-leptin (P < .001). Mean adipocyte size and total adipocyte number correlated strongly with omental weight (r = 0.6-0.8; P < .0001), irrespective of body mass index and total body fat mass, and accounted almost in total for interindividual variations in omental size. However, stepwise regression analysis demonstrated that adipocyte number was significantly (P < .0001) more important (62%) than adipocyte size (35%).CONCLUSION: The size of the major omentum is representative for VAT mass and correlates with a pernicious metabolic profile. Variations in omental weight are primarily determined by adipocyte number and to a lesser degree by adipocyte size, suggesting that increased VAT mass in obesity is predominantly dependent on adipocyte proliferation.
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5.
  • Bentzer, Peter, et al. (författare)
  • Supersensitivity in rat micro-arteries after short-term denervation
  • 1997
  • Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 161:2, s. 125-133
  • Tidskriftsartikel (refereegranskat)abstract
    • Contractile responses to phenylephrine and high-K+ were investigated in vitro in microvascular preparations from the rat medial plantar artery, a branch from the saphenous artery, obtained after short-term denervation in vivo. Two groups of animals were studied: (1) animals undergoing surgical resection of the saphenous nerve, and (2) animals undergoing surgical resection of both the sciatic and saphenous nerves. The animals were operated on one side only. Microvascular preparations (diameter about 325 microns) were obtained 10 days after surgery. Vessels from the non-operated side served as controls. Immunocytochemistry showed a decreased number of both neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) immunoreactive nerve fibres in vessels after resection of the saphenous nerve only. Resection of both the saphenous and the sciatic nerve caused a complete loss of immunoreactive nerve fibres. Mechanical measurements were performed using a wire myograph. In vessels subjected to resection of the saphenous nerve the sensitivity to phenylephrine was similar to controls. Vessels denervated by resection of both the saphenous and sciatic nerves showed significant increases in phenylephrine and potassium sensitivity. When depolarized in high-K+ solution the denervated vessels showed an increased sensitivity to extracellular Ca2+. The results show that complete short-term denervation of the rat medial plantar artery in vivo causes a pronounced supersensitivity in the vascular smooth muscle. The supersensitivity appears not to be restricted to the sympathetic alpha-receptors but also associated with changes in the cellular excitation-contraction coupling. Such altered reactivity of the vascular smooth muscle may contribute to vascular disturbances observed in vivo after nerve damage or surgical denervation.
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6.
  • Brännmark, Cecilia, 1983- (författare)
  • Insulin Signaling in Human Adipocytes a Systems Biology Approach
  • 2012
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Obesity and a sedentary life style are associated with type 2 diabetes, a disease starting with insulin resistance in the adipose tissue, which spreads to the whole body. Despite large research efforts to understand the insulin signaling system, there is little knowledge of the mechanisms behind insulin resistance and type 2 diabetes developments. We have herein focused on the insulin signaling in adipocytes, elucidating mechanisms for early signaling. We have also modeled isolated adipocytes and data from the in vivo, whole bodysituation, concurrently. We also mapped and quantitatively described differences in the insulin signaling of adipocytes from type 2 diabetics and non-diabetics.In paper I we show that neither insulin degradation, receptor internalization, nor feedback signals can as separate explanations cause the overshoot in tyrosine phosphorylation of IRS1, while an endocytosis-dependent feedback mechanism explains all available data.In paper II we show that it is not possible to scale up the experimentally determined glucose uptake by isolated human adipocytes to match the glucose uptake profile of the whole adipose tissue in vivo. Other insulin effects need to be accounted for.In paper III we show that attenuation of the positive feedback to serine 307 phosphorylation of IRS1 can explain the insulin resistance in the insulin signaling in adipocytes seen in type 2 diabetes. However, to fully explain both the signaling and the glucose uptake, a reduction in the amount of Glut4 is also needed.
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7.
  • El-Sayed, Najib M., et al. (författare)
  • The genome sequence of Trypanosoma cruzi, etiologic agent of Chagas disease.
  • 2005
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 309:5733, s. 409-15
  • Tidskriftsartikel (refereegranskat)abstract
    • Whole-genome sequencing of the protozoan pathogen Trypanosoma cruzi revealed that the diploid genome contains a predicted 22,570 proteins encoded by genes, of which 12,570 represent allelic pairs. Over 50% of the genome consists of repeated sequences, such as retrotransposons and genes for large families of surface molecules, which include trans-sialidases, mucins, gp63s, and a large novel family (>1300 copies) of mucin-associated surface protein (MASP) genes. Analyses of the T. cruzi, T. brucei, and Leishmania major (Tritryp) genomes imply differences from other eukaryotes in DNA repair and initiation of replication and reflect their unusual mitochondrial DNA. Although the Tritryp lack several classes of signaling molecules, their kinomes contain a large and diverse set of protein kinases and phosphatases; their size and diversity imply previously unknown interactions and regulatory processes, which may be targets for intervention.
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8.
  • Jernås, Margareta, 1961, et al. (författare)
  • Regulation of carboxylesterase 1 (CES1) in human adipose tissue.
  • 2009
  • Ingår i: Biochemical and biophysical research communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 383:1, s. 63-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Carboxylesterase 1 (CES1) has recently been suggested to play a role in lipolysis. Our aim was to study the regulation of CES1 expression in human adipose tissue. In the SOS Sib Pair Study, CES1 expression was higher in obese compared with lean sisters (n=78 pairs, P=8.7x10(-18)) and brothers (n=12 pairs, P=0.048). CES1 expression was higher in subcutaneous compared with omental adipose tissue in lean (P=0.027) and obese subjects (P=0.00036), and reduced during diet-induced weight loss (n=24, weeks 8, 16, and 18 compared to baseline, P<0.0001 for all time points). CES1 expression was higher in isolated adipocytes compared with intact adipose tissue (P=0.0018) and higher in large compared with small adipocytes (P=4.1x10(-6)). Basal and stimulated lipolysis was not different in individuals with high, intermediate, and low expression of CES1. Thus, CES1 expression was linked to body fat and adipocyte fat content but not to lipolytic activity.
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9.
  • Olofsson, Peder S., et al. (författare)
  • Blood pressure regulation by CD4+ lymphocytes expressing choline acetyltransferase
  • 2016
  • Ingår i: Nature Biotechnology. - : Nature Publishing Group. - 1087-0156 .- 1546-1696. ; 34:10, s. 1066-1071
  • Tidskriftsartikel (refereegranskat)abstract
    • Blood pressure regulation is known to be maintained by a neuro-endocrine circuit, but whether immune cells contribute to blood pressure homeostasis has not been determined. We previously showed that CD4(+) T lymphocytes that express choline acetyltransferase (ChAT), which catalyzes the synthesis of the vasorelaxant acetylcholine, relay neural signals(1). Here we show that these CD4(+)CD44(hi)CD62L(Io) T helper cells by gene expression are a distinct T-cell population defined by ChAT (CD4 T-ChAT). Mice lacking ChAT expression in CD4(+) cells have elevated arterial blood pressure, compared to littermate controls. Jurkat T cells overexpressing ChAT (JT(ChAT)) decreased blood pressure when infused into mice. Co-incubation of JT(ChAT) and endothelial cells increased endothelial cell levels of phosphorylated endothelial nitric oxide synthase, and of nitrates and nitrites in conditioned media, indicating increased release of the potent vasorelaxant nitric oxide. The isolation and characterization of CD4 T-ChAT cells will enable analysis of the role of these cells in hypotension and hypertension, and may suggest novel therapeutic strategies by targeting cell-mediated vasorelaxation.
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10.
  • Ryden, Mikael, et al. (författare)
  • Transplanted Bone Marrow-Derived Cells Contribute to Human Adipogenesis
  • 2015
  • Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131 .- 1932-7420. ; 22:3, s. 408-417
  • Tidskriftsartikel (refereegranskat)abstract
    • Because human white adipocytes display a high turnover throughout adulthood, a continuous supply of precursor cells is required to maintain adipogenesis. Bone marrow (BM)-derived progenitor cells may contribute to mammalian adipogenesis; however, results in animal models are conflicting. Here we demonstrate in 65 subjects who underwent allogeneic BM or peripheral blood stem cell (PBSC) transplantation that, over the entire lifespan, BM/PBSC-derived progenitor cells contribute similar to 10% to the subcutaneous adipocyte population. While this is independent of gender, age, and different transplantation-related parameters, body fat mass exerts a strong influence, with up to 2.5-fold increased donor cell contribution in obese individuals. Exome and whole-genome sequencing of single adipocytes suggests that BM/PBSC-derived progenitors contribute to adipose tissue via both differentiation and cell fusion. Thus, at least in the setting of transplantation, BM serves as a reservoir for adipocyte progenitors, particularly in obese subjects.
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11.
  • Stenkula, Karin, 1973- (författare)
  • A molecular approach to insulin signalling and caveolae in primary adipocytes
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The prevalence of type II diabetes is increasing at an alarming rate due to the western world lifestyle. Type II diabetes is characterized by an insulin resistance distinguished by impaired glucose uptake in adipose and muscle tissues. The molecular mechanisms behind the insulin recistance and also the knowledge considering normal insulin signalling in fat cells, especially in humans, are still unclear.Insulin receptor substrate (IRS) is known to be important for medating the insulin-induced signal from the insulin receptor into the cell. We developed and optimized a method for transfection of primary human adipocytes by electroporation. By recombinant expression of proteins, we found a proper IRS to be crucial for both mitogenic and metabolic signalling in human adipocytes. In human, but not rat, primary adipocytes we found IRS1 to be located at the plasma membrane in non-insulin stimulated cells. Insulin stimulation resulted in a two-fold increase of the amount of IRS1 at the plasma membrane in human cells, compared with a 12-fold increase in rat cells. By recombinant expression of IRS1 we found the species difference between human and rat IRS1 to depend on the IRS proteins and not on properties of the host cell.The adipocytes function as an energy store, critical for maintaining the energy balance, and obesity strongly correlates with insulin resistance. The insulin sensitivity of the adipocytes with regard to the size of the cells was examined by separating small and large cells from the same subject. We found no increase of the GLUT4 translocation to the plasma membrane following insulin stimulation in the large cells, whereas there was a two-fold increase in the small cells. This finding supports the idea of a causal relationship between the enlarged fat cells and reduced insulin sensitivity found in obese subjects.The insulin receptor is located and functional in a specific membrane structure, the caveola. The morphology of the caveola and the localization of the caveolar marker proteins caveolin-1 and -2 were examined. Caveolae were shown to be connected to the exterior by a narrow neck. Caveolin was found to be located at the neck region of caveolae, which imply importance of caveolin for maintaining and sequestering caveolae to the plasma membrane.In conclusion, the transfection technique proved to be highly useful for molecular biological studies of insulin signal transduction and morphology in primary adipocytes.
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12.
  • Abreu-Vieira, Gustavo, et al. (författare)
  • Cidea improves the metabolic profile through expansion of adipose tissue
  • 2015
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • In humans, Cidea (cell death-inducing DNA fragmentation factor alpha-like effector A) is highly but variably expressed in white fat, and expression correlates with metabolic health. Here we generate transgenic mice expressing human Cidea in adipose tissues (aP2-hCidea mice) and show that Cidea is mechanistically associated with a robust increase in adipose tissue expandability. Under humanized conditions (thermoneutrality, mature age and prolonged exposure to high-fat diet), aP2-hCidea mice develop a much more pronounced obesity than their wild-type littermates. Remarkably, the malfunctioning of visceral fat normally caused by massive obesity is fully overcome-perilipin 1 and Akt expression are preserved, tissue degradation is prevented, macrophage accumulation is decreased and adiponectin expression remains high. Importantly, the aP2-hCidea mice display enhanced insulin sensitivity. Our data establish a functional role for Cidea and suggest that, in humans, the association between Cidea levels in white fat and metabolic health is not only correlative but also causative.
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13.
  • Alastair, Kerr, et al. (författare)
  • The long noncoding RNA ADIPINT is a gatekeeper of pyruvate carboxylasefunction regulating human fat cell metabolism
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The pleiotropic function of long noncoding RNAs (lncRNAs) is well recognized,but their direct role in governingmetabolic homeostasis is less understood. Herein,we describe a human adipocyte-specific lncRNA, ADIPINT, that regulatespyruvate carboxylase (PC) an enzyme pivotal to energy metabolism. With a novelapproach, Targeted RNA-protein identification using Orthogonal Organic PhaseSeparation (TROOPS) and validation with electron microscopy, we show thatADIPINT binds to PC. ADIPINT knockdown alters the interactome anddecreases the mitochondrial abundance and enzymatic activty of PC. Decreases inADIPINT or PC expression reduce adipocyte lipid synthesis, breakdown and lipidcontent. In human white adipose tissue, ADIPINT expression is increased inobesity, linked to fat cell size, adipose insulin resistance and PC activity. Thus, weidentify ADIPINT as a regulator of lipid metabolism in human white adipocytes,which at least in part is mediated through its interaction with PC.
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14.
  • Andersson, Daniel P., et al. (författare)
  • Omentectomy in addition to gastric bypass surgery and influence on insulin sensitivity : A randomized double blind controlled trial
  • 2014
  • Ingår i: Clinical Nutrition. - : Elsevier BV. - 0261-5614 .- 1532-1983. ; 33:6, s. 991-996
  • Tidskriftsartikel (refereegranskat)abstract
    • Background & aims: Accumulation of visceral adipose tissue is associated with insulin resistance and cardio-vascular disease. The aim of this study was to elucidate whether removal of a large amount of visceral fat by omentectomy in conjunction with Roux en-Y gastric bypass operation (RYGB) results in enhanced improvement of insulin sensitivity compared to gastric bypass surgery alone. Methods: Eighty-one obese women scheduled for RYGB were included in the study. They were randomized to RYGB or RYGB in conjunction with omentectomy. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp before operation and sixty-two women were also reexamined 2 years post-operatively. The primary outcome measure was insulin sensitivity and secondary outcome measures included cardio-metabolic risk factors. Results: Two-year weight loss was profound but unaffected by omentectomy. Before intervention, there were no clinical or metabolic differences between the two groups. The difference in primary outcome measure, insulin sensitivity, was not significant between the non-omentectomy (6.7 +/- 1.6 mg/kg body weight/minute) and omentectomy groups (6.6 +/- 1.5 mg/kg body weight/minute) after 2 years. Nor did any of the cardio-metabolic risk factors that were secondary outcome measures differ significantly. Conclusion: Addition of omentectomy to gastric bypass operation does not give an incremental effect on long term insulin sensitivity or cardio-metabolic risk factors. The clinical usefulness of omentectomy in addition to gastric bypass operation is highly questionable.
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15.
  • Aydemir, Umut, et al. (författare)
  • In situ assembly of an injectable cardiac stimulator
  • 2024
  • Ingår i: Nature Communications. - 2041-1723. ; 15
  • Tidskriftsartikel (refereegranskat)abstract
    • Without intervention, cardiac arrhythmias pose a risk of fatality. However, timely intervention can be challenging in environments where transporting a large, heavy defibrillator is impractical, or emergency surgery to implant cardiac stimulation devices is not feasible. Here, we introduce an injectable cardiac stimulator, a syringe loaded with a nanoparticle solution comprising a conductive polymer and a monomer that, upon injection, forms a conductive structure around the heart for cardiac stimulation. Following treatment, the electrode is cleared from the body, eliminating the need for surgical extraction. The mixture adheres to the beating heart in vivo without disrupting its normal rhythm. The electrofunctionalized injectable cardiac stimulator demonstrates a tissue-compatible Young’s modulus of 21 kPa and a high conductivity of 55 S/cm. The injected electrode facilitates electrocardiogram measurements, regulates heartbeat in vivo, and rectifies arrhythmia. Conductive functionality is maintained for five consecutive days, and no toxicity is observed at the organism, organ, or cellular levels.
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17.
  • Bjermo, Helena, et al. (författare)
  • Effects of n-6 PUFAs compared with SFAs on liver fat, lipoproteins, and inflammation in abdominal obesity : a randomized controlled trial
  • 2012
  • Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 95:5, s. 1003-1012
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Replacing SFAs with vegetable PUFAs has cardiometabolic benefits, but the effects on liver fat are unknown. Increased dietary n-6 PUFAs have, however, also been proposed to promote inflammation-a yet unproven theory. OBJECTIVE: We investigated the effects of PUFAs on liver fat, systemic inflammation, and metabolic disorders. DESIGN: We randomly assigned 67 abdominally obese subjects (15% had type 2 diabetes) to a 10-wk isocaloric diet high in vegetable n-6 PUFA (PUFA diet) or SFA mainly from butter (SFA diet), without altering the macronutrient intake. Liver fat was assessed by MRI and magnetic resonance proton (1H) spectroscopy (MRS). Proprotein convertase subtilisin/kexin type-9 (PCSK9, a hepatic LDL-receptor regulator), inflammation, and adipose tissue expression of inflammatory and lipogenic genes were determined. RESULTS: A total of 61 subjects completed the study. Body weight modestly increased but was not different between groups. Liver fat was lower during the PUFA diet than during the SFA diet [between-group difference in relative change from baseline; 16% (MRI; P < 0.001), 34% (MRS; P = 0.02)]. PCSK9 (P = 0.001), TNF receptor-2 (P < 0.01), and IL-1 receptor antagonist (P = 0.02) concentrations were lower during the PUFA diet, whereas insulin (P = 0.06) tended to be higher during the SFA diet. In compliant subjects (defined as change in serum linoleic acid), insulin, total/HDL-cholesterol ratio, LDL cholesterol, and triglycerides were lower during the PUFA diet than during the SFA diet (P < 0.05). Adipose tissue gene expression was unchanged. CONCLUSIONS: Compared with SFA intake, n-6 PUFAs reduce liver fat and modestly improve metabolic status, without weight loss. A high n-6 PUFA intake does not cause any signs of inflammation or oxidative stress. Downregulation of PCSK9 could be a novel mechanism behind the cholesterol-lowering effects of PUFAs.
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20.
  • Claussnitzer, Melina, et al. (författare)
  • Leveraging cross-species transcription factor binding site patterns: from diabetes risk Loci to disease mechanisms.
  • 2014
  • Ingår i: Cell. - : Elsevier BV. - 1097-4172 .- 0092-8674. ; 156:1-2, s. 343-358
  • Tidskriftsartikel (refereegranskat)abstract
    • Genome-wide association studies have revealed numerous risk loci associated with diverse diseases. However, identification of disease-causing variants within association loci remains a major challenge. Divergence in gene expression due to cis-regulatory variants in noncoding regions is central to disease susceptibility. We show that integrative computational analysis of phylogenetic conservation with a complexity assessment of co-occurring transcription factor binding sites (TFBS) can identify cis-regulatory variants and elucidate their mechanistic role in disease. Analysis of established type 2 diabetes risk loci revealed a striking clustering of distinct homeobox TFBS. We identified the PRRX1 homeobox factor as a repressor of PPARG2 expression in adipose cells and demonstrate its adverse effect on lipid metabolism and systemic insulin sensitivity, dependent on the rs4684847 risk allele that triggers PRRX1 binding. Thus, cross-species conservation analysis at the level of co-occurring TFBS provides a valuable contribution to the translation of genetic association signals to disease-related molecular mechanisms.
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21.
  • Collins, Ruairi, et al. (författare)
  • Biochemical discrimination between selenium and sulfur 1 : a single residue provides selenium specificity to human selenocysteine lyase
  • 2012
  • Ingår i: PLoS One. - Stockholm : Karolinska Institutet, Dept of Medical Biochemistry and Biophysics. - 1932-6203.
  • Tidskriftsartikel (refereegranskat)abstract
    • Selenium and sulfur are two closely related basic elements utilized in nature for a vast array of biochemical reactions. While toxic at higher concentrations, selenium is an essential trace element incorporated into selenoproteins as selenocysteine (Sec), the selenium analogue of cysteine (Cys). Sec lyases (SCLs) and Cys desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys and generally act on both substrates. In contrast, human SCL (hSCL) is specific for Sec although the only difference between Sec and Cys is the identity of a single atom. The chemical basis of this selenium-over-sulfur discrimination is not understood. Here we describe the X-ray crystal structure of hSCL and identify Asp146 as the key residue that provides the Sec specificity. A D146K variant resulted in loss of Sec specificity and appearance of CD activity. A dynamic active site segment also provides the structural prerequisites for direct product delivery of selenide produced by Sec cleavage, thus avoiding release of reactive selenide species into the cell. We thus here define a molecular determinant for enzymatic specificity discrimination between a single selenium versus sulfur atom, elements with very similar chemical properties. Our findings thus provide molecular insights into a key level of control in human selenium and selenoprotein turnover and metabolism.
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22.
  • Dahlman, Ingrid, et al. (författare)
  • A unique role of monocyte chemoattractant protein 1 among chemokines in adipose tissue of obese subjects
  • 2005
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 90:10, s. 5834-5840
  • Tidskriftsartikel (refereegranskat)abstract
    • Context: Low-grade inflammation in adipose tissue may contribute to insulin resistance in obesity. However, the roles of individual inflammatory mediators in adipose tissue are poorly understood. Objectives: The objective of this study was to determine which inflammation markers are most overexpressed at the gene level in adipose tissue in human obesity and how this relates to corresponding protein secretion. Design: We examined gene expression profiles in 17 lean and 20 obese subjects. The secretory pattern of relevant corresponding proteins was examined in human sc adipose tissue or isolated fat cells in vitro and in vivo in several obese or lean cohorts. Results: In ranking gene expression, defined pathways associated with obesity and immune and defense responses scored high. Among seven markedly overexpressed chemokines, only monocyte chemoattractant protein 1 (MCP1) was released from adipose tissue and isolated fat cells in vitro. In obesity, the secretion and expression of MCP1 in adipose tissue pieces were more than 6- and 2-fold increased, respectively, but there was no change in circulating MCP1 levels. There was no net release of MCP1, but there was a net release of leptin, in vivo from adipose tissue into the circulation. Conclusions: Obesity is associated with the increased expression of several chemokine genes in adipose tissue. However, only MCP1 is secreted into the extracellular space, where it primarily acts as a local factor, because little or no spillover into the circulation occurs. MCP1 influences the function of adipocytes, is a recruitment factor for macrophages, and may be a crucial link among chemokines between adipose tissue inflammation and insulin resistance.
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24.
  • Eliasson, Ann-Christin, et al. (författare)
  • The Manual Ability Classification System (MACS) for children with cerebral palsy: scale development and evidence of validity and reliability
  • 2006
  • Ingår i: Developmental Medicine & Child Neurology. - : Wiley. - 0012-1622 .- 1469-8749. ; 48:7, s. 549-554
  • Tidskriftsartikel (refereegranskat)abstract
    • The Manual Ability Classification System (MACS) has been developed to classify how children with cerebral palsy (CP) use their hands when handling objects in daily activities. The classification is designed to reflect the child's typical manual performance, not the child's maximal capacity. It classifies the collaborative use of both hands together. Validation was based on the experience within an expert group, a review of the literature, and thorough analysis of children across a spectrum of function. Discussions continued until consensus was reached, first about the constructs, then about the content of the five levels. Parents and therapists were interviewed about the content and the description of levels. Reliability was tested between pairs of therapists for 168 children (70 females, 98 males; with hemiplegia [n=52], diplegia [n=70], tetraplegia [n=19], ataxia [n=6], dyskinesia [n=19], and unspecified CP [n=2]) between 4 and 18 years and between 25 parents and their children's therapists. The results demonstrated that MACS has good validity and reliability. The intraclass correlation coefficient between therapists was 0.97 (95% confidence interval 0.96-0.98), and between parents and therapist was 0.96 (0.89-0.98), indicating excellent agreement.
  •  
25.
  • Enoksson, Staffan, et al. (författare)
  • Marked Re-Utilization of Free Fatty Acids During Activated Lipolysis in Human Skeletal Muscle.
  • 2005
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 90:2, s. 1189-1195
  • Tidskriftsartikel (refereegranskat)abstract
    • Release of glycerol and free fatty acids (FFA) was investigated in human skeletal muscle strips. In the basal state, glycerol and FFA were released at almost equimolar rates (0.3 nmol/ng tissue.90 min). A nonselective beta-adrenoceptor agonist, isoprenaline, caused a concentration-dependent stimulation of glycerol release, whereas FFA release was unaffected. Basal and isoprenaline-induced glycerol release correlated positively with the age of the donors (r = 0.5, P < 0.005) but not with their body mass index (P > or = 0.4). Biochemical experiments with hormone-sensitive lipase (HSL) showed that most enzyme activity was both in the cytosol and mitochondrial fraction and that it constituted the common long and active form of the protein. Electron microscopy studies in rat skeletal muscle using labeled highly specific HSL antibodies verified the cytosolic location of HSL and, furthermore, indicated an accumulation of HSL-adjoining mitochondria. These results suggest that FFA produced in myocytes during catecholamine-induced lipolysis are retained by the muscle and, therefore by inference, reused. It is conceivable that efficient hydrolysis of acylglycerol by HSL located in the cytosol as well as near the mitochondria may facilitate mitochondrial FFA oxidation. In addition, muscle lipolysis activity increases during aging and may be independent of total body fat.
  •  
26.
  • Flanagan, John N., et al. (författare)
  • Role of follistatin in promoting adipogenesis in women
  • 2009
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 94:8, s. 3003-9
  • Tidskriftsartikel (refereegranskat)abstract
    • CONTEXT: Follistatin is a glycoprotein that binds and neutralizes biological activities of TGFbeta superfamily members including activin and myostatin. We previously identified by expression profiling that follistatin levels in white adipose tissue (WAT) were regulated by obesity. OBJECTIVE: The objective of the study was to elucidate the role of follistatin in human WAT and obesity. DESIGN: We measured secreted follistatin protein from WAT biopsies and fat cells in vitro. We also quantified follistatin mRNA expression in sc and visceral WAT and in WAT-fractionated cells and related it to obesity status, body region, and cellular origin. We investigated the effects of follistatin on adipocyte differentiation of progenitor cells in vitro. PARTICIPANTS: Women (n = 66) with a wide variation in body mass index were recruited by advertisement and from a clinic for weight-reduction therapy. RESULTS: WAT secreted follistatin in vitro. Follistatin mRNA levels in sc but not visceral WAT were decreased in obesity and restored to nonobese levels after weight reduction. Follistatin mRNA levels were high in the stroma-vascular fraction of WAT and low in adipocytes. Recombinant follistatin treatment promoted adipogenic differentiation of progenitor cells and neutralized the inhibitory action of myostatin on differentiation in vitro. Moreover, activin and myostatin signaling receptors were detected in WAT and adipocytes. CONCLUSION: Follistatin is a new adipokine important for adipogenesis. Down-regulated WAT expression of follistatin in obesity may counteract adiposity but could, by inhibiting adipogenesis, contribute to hypertrophic obesity (large fat cells) and insulin resistance.
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27.
  • Girousse, Amandine, et al. (författare)
  • Partial Inhibition of Adipose Tissue Lipolysis Improves Glucose Metabolism and Insulin Sensitivity Without Alteration of Fat Mass
  • 2013
  • Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 11:2
  • Tidskriftsartikel (refereegranskat)abstract
    • When energy is needed, white adipose tissue (WAT) provides fatty acids (FAs) for use in peripheral tissues via stimulation of fat cell lipolysis. FAs have been postulated to play a critical role in the development of obesity-induced insulin resistance, a major risk factor for diabetes and cardiovascular disease. However, whether and how chronic inhibition of fat mobilization from WAT modulates insulin sensitivity remains elusive. Hormone-sensitive lipase (HSL) participates in the breakdown of WAT triacylglycerol into FAs. HSL haploinsufficiency and treatment with a HSL inhibitor resulted in improvement of insulin tolerance without impact on body weight, fat mass, and WAT inflammation in high-fat-diet-fed mice. In vivo palmitate turnover analysis revealed that blunted lipolytic capacity is associated with diminution in FA uptake and storage in peripheral tissues of obese HSL haploinsufficient mice. The reduction in FA turnover was accompanied by an improvement of glucose metabolism with a shift in respiratory quotient, increase of glucose uptake in WAT and skeletal muscle, and enhancement of de novo lipogenesis and insulin signalling in liver. In human adipocytes, HSL gene silencing led to improved insulin-stimulated glucose uptake, resulting in increased de novo lipogenesis and activation of cognate gene expression. In clinical studies, WAT lipolytic rate was positively and negatively correlated with indexes of insulin resistance and WAT de novo lipogenesis gene expression, respectively. In obese individuals, chronic inhibition of lipolysis resulted in induction of WAT de novo lipogenesis gene expression. Thus, reduction in WAT lipolysis reshapes FA fluxes without increase of fat mass and improves glucose metabolism through cell-autonomous induction of fat cell de novo lipogenesis, which contributes to improved insulin sensitivity.
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28.
  • Göransson, Olga, et al. (författare)
  • Dimethylaminopurine inhibits metabolic effects of insulin in primary adipocytes.
  • 2004
  • Ingår i: Journal of Nutritional Biochemistry. - : Elsevier BV. - 1873-4847 .- 0955-2863. ; 15:5, s. 303-312
  • Tidskriftsartikel (refereegranskat)abstract
    • Dimethylaminopurine (DMAP) has previously been used as an inhibitor of phosphorylation in studies of meiotic events, and more recently to investigate TNFα signaling, because of its potential to inhibit activation of c-jun N-terminal kinase (JNK). Here we have addressed the effects of DMAP on metabolic insulin responses in adipocytes and on intracellular insulin signaling molecules. At 100 μmol/L, DMAP completely inhibited the ability of insulin to counteract lipolysis in isolated adipocytes. Insulin-induced lipogenesis and glucose uptake was inhibited to a lesser degree in a concentration-dependent manner starting at 10 μmol/L DMAP. Insulin-induced tyrosine phosphorylation of the insulin receptor was not affected by DMAP. Insulin-induced activation of protein kinase B, a known mediator of insulin action, was not inhibited by 100 μmol/L, but to a low extent by 1 mmol/L DMAP in intact cells. This inhibition was not sufficient to affect activation of the downstream protein kinase B substrate phosphodiesterase 3B. The inhibition of activation of JNK as a possible mechanism whereby DMAP affects insulin-induced antilipolysis, lipogenesis, and glucose uptake, was investigated using the JNK inhibitor SP600125. At 100 μmol/L, SP600125 completely reversed the antilipolytic effect of insulin, as well as partially inhibited insulin-induced lipogenesis and glucose-uptake, indicating that JNK may be involved in mediating these actions of insulin. Inhibition of JNK by DMAP may therefore partly explain the negative impact of DMAP on insulin action in adipocytes.
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29.
  • Herdenberg, Carl, et al. (författare)
  • LRIG proteins regulate lipid metabolism via BMP signaling and affect the risk of type 2 diabetes
  • 2021
  • Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4
  • Tidskriftsartikel (refereegranskat)abstract
    • Leucine-rich repeats and immunoglobulin-like domains (LRIG) proteins have been implicated as regulators of growth factor signaling; however, the possible redundancy among mammalian LRIG1, LRIG2, and LRIG3 has hindered detailed elucidation of their physiological functions. Here, we show that Lrig-null mouse embryonic fibroblasts (MEFs) are deficient in adipogenesis and bone morphogenetic protein (BMP) signaling. In contrast, transforming growth factor-beta (TGF-β) and receptor tyrosine kinase (RTK) signaling appeared unaltered in Lrig-null cells. The BMP signaling defect was rescued by ectopic expression of LRIG1 or LRIG3 but not by expression of LRIG2. Caenorhabditis elegans with mutant LRIG/sma-10 variants also exhibited a lipid storage defect. Human LRIG1 variants were strongly associated with increased body mass index (BMI) yet protected against type 2 diabetes; these effects were likely mediated by altered adipocyte morphology. These results demonstrate that LRIG proteins function as evolutionarily conserved regulators of lipid metabolism and BMP signaling and have implications for human disease.
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30.
  • Jaworowski, Åsa, et al. (författare)
  • Calponin reduces shortening velocity in skinned taenia coli smooth muscle fibres
  • 1995
  • Ingår i: FEBS Letters. - 1873-3468. ; 365:2-3, s. 167-171
  • Tidskriftsartikel (refereegranskat)abstract
    • Calponin (4.1-5.9 microM, pig stomach) inhibited maximal shortening velocity (Vmax) by 20-25% with only minor influence on force in skinned smooth muscle from guinea-pig taenia coli activated at different Ca2+ levels and with thiophosphorylation. Similar results were obtained with a fragment of the N-terminal 1-228 amino acids engineered using a mouse cDNA construct (5.4 microM). Both the native calponin and the fragment inhibited actin filament sliding in a graded manner in an in vitro motility assay. We conclude that calponin influences the kinetics of the actin-myosin interaction in the organised smooth muscle contractile system and that engineered fragments of calponin can be used to probe its action in muscle fibres. The effects can be due to an introduction of an internal load during filament sliding, possibly by decreasing the detachment rates and increasing the cross-bridge time spent in the attached state.
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31.
  • Jersin, R. A., et al. (författare)
  • Role of the Neutral Amino Acid Transporter SLC7A10 in Adipocyte Lipid Storage, Obesity, and Insulin Resistance
  • 2021
  • Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 70:3, s. 680-695
  • Tidskriftsartikel (refereegranskat)abstract
    • Elucidation of mechanisms that govern lipid storage, oxidative stress, and insulin resistance may lead to improved therapeutic options for type 2 diabetes and other obesity-related diseases. Here, we find that adipose expression of the small neutral amino acid transporter SLC7A10, also known as alanine-serine-cysteine transporter-1 (ASC-1), shows strong inverse correlates with visceral adiposity, insulin resistance, and adipocyte hypertrophy across multiple cohorts. Concordantly, loss of Slc7a10 function in zebrafish in vivo accelerates diet-induced body weight gain and adipocyte enlargement. Mechanistically, SLC7A10 inhibition in human and murine adipocytes decreases adipocyte serine uptake and total glutathione levels and promotes reactive oxygen species (ROS) generation. Conversely, SLC7A10 overexpression decreases ROS generation and increases mitochondrial respiratory capacity. RNA sequencing revealed consistent changes in gene expression between human adipocytes and zebrafish visceral adipose tissue following loss of SLC7A10, e.g., upregulation of SCD (lipid storage) and downregulation of CPT1A (lipid oxidation). Interestingly, ROS scavenger reduced lipid accumulation and attenuated the lipid-storing effect of SLC7A10 inhibition. These data uncover adipocyte SLC7A10 as a novel important regulator of adipocyte resilience to nutrient and oxidative stress, in part by enhancing glutathione levels and mitochondrial respiration, conducive to decreased ROS generation, lipid accumulation, adipocyte hypertrophy, insulin resistance, and type 2 diabetes.
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32.
  • Jiao, Hong, et al. (författare)
  • Genetic Association and Gene Expression Analysis Identify FGFR1 as a New Susceptibility Gene for Human Obesity
  • 2011
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 96:6, s. E962-E966
  • Tidskriftsartikel (refereegranskat)abstract
    • Context: Previous studies suggest a role for fibroblast growth factor receptor 1 (FGFR1) in the regulation of energy balance. Objective: Our objective was to investigate whether FGFR1 is an obesity gene by genetic association and functional studies. Design: The study was designed to genotype common FGFR1 single-nucleotide polymorphisms (SNP) in large cohorts, confirm significant results in additional cohorts, and measure FGFR1 expression in human adipose tissue and in rodent hypothalamus. Setting: General community and referral centers for specialized care was the setting for the study. Participants: We genotyped FGFR1 SNP in 2438 obese and 2115 lean adults and 985 obese and 532 population-based children. Results were confirmed in 928 obese and 2738 population-based adults and 487 obese and 441 lean children. Abdominal sc adipose tissue was investigated in 202 subjects. We also investigated diet-induced, obese fasting, and fed rats. Main Outcome Measures: We analyzed the association between FGFR1 SNP and obesity. In secondary analyses, we related adipose FGFR1 expression to genotype, obesity, and degree of fat cell differentiation and related hypothalamic FGFR1 to energy balance. Results: FGFR1 rs7012413*T was nominally associated with obesity in all four cohorts; metaanalysis odds ratio = 1.17 (95% confidence interval = 1.10-1.25), and P = 1.8 x 10(-6), which was P = 7.0 x 10(-8) in the recessive model. rs7012413*T was associated with FGFR1 expression in adipose tissue (P < 0.0001). In this organ, but not in skeletal muscle, FGFR1 mRNA (P < 0.0001) and protein (P < 0.05) were increased in obesity. In rats, hypothalamic expression of FGFR1 declined after fasting (P < ]0.001) and increased after diet-induced obesity (P < 0.05). Conclusions: FGFR1 is a novel obesity gene that may promote obesity by influencing adipose tissue and the hypothalamic control of appetite.
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33.
  • Jiao, Hong, et al. (författare)
  • Genome wide association study identifies KCNMA1 contributing to human obesity
  • 2011
  • Ingår i: BMC Medical Genomics. - : Springer Science and Business Media LLC. - 1755-8794. ; 4, s. 51-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Recent genome-wide association (GWA) analyses have identified common single nucleotide polymorphisms (SNPs) that are associated with obesity. However, the reported genetic variation in obesity explains only a minor fraction of the total genetic variation expected to be present in the population. Thus many genetic variants controlling obesity remain to be identified. The aim of this study was to use GWA followed by multiple stepwise validations to identify additional genes associated with obesity. Methods: We performed a GWA analysis in 164 morbidly obese subjects (BMI: body mass index > 40 kg/m(2)) and 163 Swedish subjects (> 45 years) who had always been lean. The 700 SNPs displaying the strongest association with obesity in the GWA were analyzed in a second cohort comprising 460 morbidly obese subjects and 247 consistently lean Swedish adults. 23 SNPs remained significantly associated with obesity (nominal P< 0.05) and were in a step-wise manner followed up in five additional cohorts from Sweden, France, and Germany together comprising 4214 obese and 5417 lean or population-based control individuals. Three samples, n = 4133, were used to investigate the population-based associations with BMI. Gene expression in abdominal subcutaneous adipose tissue in relation to obesity was investigated for 14 adults. Results: Potassium channel, calcium activated, large conductance, subfamily M, alpha member (KCNMA1) rs2116830*G and BDNF rs988712*G were associated with obesity in five of six investigated case-control cohorts. In meta-analysis of 4838 obese and 5827 control subjects we obtained genome-wide significant allelic association with obesity for KCNMA1 rs2116830*G with P = 2.82 x 10(-10) and an odds ratio (OR) based on cases vs controls of 1.26 [95% C. I. 1.12-1.41] and for BDNF rs988712*G with P = 5.2 x 10(-17) and an OR of 1.36 [95% C. I. 1.20-1.55]. KCNMA1 rs2116830*G was not associated with BMI in the population-based samples. Adipose tissue (P = 0.0001) and fat cell (P = 0.04) expression of KCNMA1 was increased in obesity. Conclusions: We have identified KCNMA1 as a new susceptibility locus for obesity, and confirmed the association of the BDNF locus at the genome-wide significant level.
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34.
  • Jocken, Johan W E, et al. (författare)
  • Adipose TriGlyceride Lipase (ATGL) and Hormone-Sensitive Lipase (HSL) protein expression is decreased in the obese insulin resistant state.
  • 2007
  • Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 92:6, s. 2292-2299
  • Tidskriftsartikel (refereegranskat)abstract
    • Obesity is associated with increased triacylglycerol (TAG) storage in adipose tissue and insulin resistance. The mobilization of stored TAG is mediated by hormone-sensitive lipase (HSL) and the recently discovered adipose triglyceride lipase (ATGL). The aim of the present study was to examine whether ATGL and HSL mRNA and protein expression are altered in insulin-resistant conditions. In addition, we investigated whether a possible impaired expression could be reversed by a period of weight reduction. METHODS: Adipose tissue biopsies were taken from obese subjects (n = 44) with a wide range of insulin resistance, before and just after a 10-wk hypocaloric diet. ATGL and HSL protein and mRNA expression was determined by Western blot and quantitative RT-PCR, respectively. RESULTS: Fasting insulin levels and the degree of insulin resistance (using the homeostasis model assessment index for insulin resistance) were negatively correlated with ATGL and HSL protein expression, independent of age, gender, fat cell size, and body composition. Both mRNA and protein levels of ATGL and HSL were reduced in insulin-resistant compared with insulin-sensitive subjects (P < 0.05). Weight reduction significantly decreased ATGL and HSL mRNA and protein expression. A positive correlation between the decrease in leptin and the decrease in ATGL protein level after weight reduction was observed. Finally, ATGL and HSL mRNA and protein levels seem to be highly correlated, indicating a tight coregulation and transcriptional control. CONCLUSIONS: In obese subjects, insulin resistance and hyperinsulinemia are strongly associated with ATGL and HSL mRNA and protein expression, independent of fat mass. Data on weight reduction indicated that also other factors (e.g. leptin) relate to ATGL and HSL protein expression.
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35.
  • Johansson, Ann-Louise, et al. (författare)
  • Biochemical discrimination between selenium and sulfur 2 : mechanistic investigation of the selenium specificity of human selenocysteine lyase
  • 2012
  • Ingår i: PLoS One. - Stockholm : Karolinska Institutet, Dept of Medical Biochemistry and Biophysics. - 1932-6203.
  • Tidskriftsartikel (refereegranskat)abstract
    • Selenium is an essential trace element incorporated into selenoproteins as selenocysteine. Selenocysteine (Sec) lyases (SCLs) and cysteine (Cys) desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys, respectively, and generally accept both substrates. Intriguingly, human SCL (hSCL) is specific for Sec even though the only difference between Sec and Cys is a single chalcogen atom. The crystal structure of hSCL was recently determined and gain-of-function protein variants that also could accept Cys as substrate were identified. To obtain mechanistic insight into the chemical basis for its substrate discrimination, we here report time-resolved spectroscopic studies comparing the reactions of the Sec-specific wild-type hSCL and the gain-of-function D146K/H389T variant, when given Cys as a substrate. The data are interpreted in light of other studies of SCL/CD enzymes and offer mechanistic insight into the function of the wild-type enzyme. Based on these results and previously available data we propose a reaction mechanism whereby the Sec over Cys specificity is achieved using a combination of chemical and physico-mechanical control mechanisms.
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36.
  • Kerr, Alastair, et al. (författare)
  • The long noncoding RNA ADIPINT is a gatekeeper of pyruvate carboxylase function regulating human fat cell metabolism
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The pleiotropic function of long noncoding RNAs (lncRNAs) is well recognized, but their direct role in governing metabolic homeostasis is less understood. Herein, we describe a human adipocyte-specific lncRNA, ADIPINT, that regulates pyruvate carboxylase (PC) an enzyme pivotal to energy metabolism. With a novel approach, Targeted RNA-protein identification using Orthogonal Organic Phase Separation (TROOPS) and validation with electron microscopy, we show that ADIPINT binds to PC.  ADIPINT knockdown alters the interactome and decreases the mitochondrial abundance and enzymatic activty of PC. Decreases in ADIPINT or PC expression reduce adipocyte lipid synthesis,  breakdown and lipid content.  In human white adipose tissue, ADIPINT expression is increased in obesity, linked to fat cell size, adipose insulin resistance and PC activity. Thus, we identify ADIPINT as a regulator of lipid metabolism in human white adipocytes, which at least in part is mediated through its interaction with PC.
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37.
  • Kolehmainen, Marjukka, et al. (författare)
  • Healthy Nordic diet downregulates the expression of genes involved in inflammation in subcutaneous adipose tissue in individuals with features of the metabolic syndrome.
  • 2015
  • Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 101:1, s. 228-239
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Previously, a healthy Nordic diet (ND) has been shown to have beneficial health effects close to those of Mediterranean diets.OBJECTIVE: The objective was to explore whether the ND has an impact on gene expression in abdominal subcutaneous adipose tissue (SAT) and whether changes in gene expression are associated with clinical and biochemical effects.DESIGN: Obese adults with features of the metabolic syndrome underwent an 18- to 24-wk randomized intervention study comparing the ND with the control diet (CD) (the SYSDIET study, carried out within Nordic Centre of Excellence of the Systems Biology in Controlled Dietary Interventions and Cohort Studies). The present study included participants from 3 Nordic SYSDIET centers [Kuopio (n = 20), Lund (n = 18), and Oulu (n = 18)] with a maximum weight change of ±4 kg, highly sensitive C-reactive protein concentration <10 mg/L at the beginning and the end of the intervention, and baseline body mass index (in kg/m(2)) <38. SAT biopsy specimens were obtained before and after the intervention and subjected to global transcriptome analysis with Gene 1.1 ST Arrays (Affymetrix).RESULTS: Altogether, 128 genes were differentially expressed in SAT between the ND and CD (nominal P < 0.01; false discovery rate, 25%). These genes were overrepresented in pathways related to immune response (adjusted P = 0.0076), resulting mainly from slightly decreased expression in the ND and increased expression in the CD. Immune-related pathways included leukocyte trafficking and macrophage recruitment (e.g., interferon regulatory factor 1, CD97), adaptive immune response (interleukin32, interleukin 6 receptor), and reactive oxygen species (neutrophil cytosolic factor 1). Interestingly, the regulatory region of the 128 genes was overrepresented for binding sites for the nuclear transcription factor κB.CONCLUSION: A healthy Nordic diet reduces inflammatory gene expression in SAT compared with a control diet independently of body weight change in individuals with features of the metabolic syndrome. The study was registered at clinicaltrials.gov as NCT00992641.
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38.
  • Laurell, Tobias, et al. (författare)
  • Identification of three novel FGF16 mutations in X-linked recessive fusion of the fourth and fifth metacarpals and possible correlation with heart disease.
  • 2014
  • Ingår i: Molecular Genetics & Genomic Medicine. - : Wiley. - 2324-9269. ; 2:5, s. 402-411
  • Tidskriftsartikel (refereegranskat)abstract
    • Nonsense mutations in FGF16 have recently been linked to X-linked recessive hand malformations with fusion between the fourth and the fifth metacarpals and hypoplasia of the fifth digit (MF4; MIM#309630). The purpose of this study was to perform careful clinical phenotyping and to define molecular mechanisms behind X-linked recessive MF4 in three unrelated families. We performed whole-exome sequencing, and identified three novel mutations in FGF16. The functional impact of FGF16 loss was further studied using morpholino-based suppression of fgf16 in zebrafish. In addition, clinical investigations revealed reduced penetrance and variable expressivity of the MF4 phenotype. Cardiac disorders, including myocardial infarction and atrial fibrillation followed the X-linked FGF16 mutated trait in one large family. Our findings establish that a mutation in exon 1, 2 or 3 of FGF16 results in X-linked recessive MF4 and expand the phenotypic spectrum of FGF16 mutations to include a possible correlation with heart disease.
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39.
  • Leder, Lena, et al. (författare)
  • Effects of a healthy Nordic diet on gene expression changes in peripheral blood mononuclear cells in response to an oral glucose tolerance test in subjects with metabolic syndrome : A SYSDIET sub-study
  • 2016
  • Ingår i: Genes & Nutrition. - : Springer Science and Business Media LLC. - 1555-8932 .- 1865-3499. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Diet has a great impact on the risk of developing features of metabolic syndrome (MetS), type 2 diabetes mellitus (T2DM), and cardiovascular diseases (CVD). We evaluated whether a long-term healthy Nordic diet (ND) can modify the expression of inflammation and lipid metabolism-related genes in peripheral blood mononuclear cells (PBMCs) during a 2-h oral glucose tolerance test (OGTT) in individuals with MetS. Methods: A Nordic multicenter randomized dietary study included subjects (n = 213) with MetS, randomized to a ND group or a control diet (CD) group applying an isocaloric study protocol. In this sub-study, we included subjects (n = 89) from three Nordic centers: Kuopio (n =26), Lund (n = 30), and Oulu (n = 33) with a maximum weight change of ±4 kg, high-sensitivity C-reactive protein concentration ≤10 mg L-1, and baseline body mass index -2. PBMCs were isolated, and the mRNA gene expression analysis was measured by quantitative real-time polymerase chain reaction (qPCR). We analyzed the mRNA expression changes of 44 genes before and after a 2hOGTT at the beginning and the end of the intervention. Results: The healthy ND significantly down-regulated the expression of toll-like receptor 4 (TLR4), interleukin 18 (IL18), and thrombospondin receptor (CD36) mRNA transcripts and significantly up-regulated the expression of peroxisome proliferator-activated receptor delta (PPARD) mRNA transcript after the 2hOGTT compared to the CD. Conclusions: A healthy ND is able to modify the gene expression in PBMCs after a 2hOGTT. However, more studies are needed to clarify the biological and clinical relevance of these findings.
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40.
  • Mulder, Hindrik, et al. (författare)
  • Hormone-sensitive lipase null mice exhibit signs of impaired insulin sensitivity whereas insulin secretion is intact.
  • 2003
  • Ingår i: Journal of Biological Chemistry. - 1083-351X .- 0021-9258. ; 278:38, s. 36380-36388
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid metabolism plays an important role in glucose homeostasis under normal and pathological conditions. In adipocytes, skeletal muscle, and pancreatic beta-cells, lipids are mobilized from acylglycerides by the hormone-sensitive lipase (HSL). Here, the consequences of a targeted disruption of the HSL gene for glucose homeostasis were examined. HSL null mice were slightly hyperglycemic in the fasted, but not fed state, which was accompanied by moderate hyperinsulinemia. During glucose challenges, however, disposal of the sugar was not affected in HSL null mice, presumably because of release of increased amounts of insulin. Impaired insulin sensitivity was further indicated by retarded glucose disposal during an insulin tolerance test. A euglycemic hyperinsulinemic clamp revealed that hepatic glucose production was insufficiently blocked by insulin in HSL null mice. In vitro, insulin-stimulated glucose uptake into soleus muscle, and lipogenesis in adipocytes were moderately reduced, suggesting additional sites of insulin resistance. Morphometric analysis of pancreatic islets revealed a doubling of beta-cell mass in HSL null mice, which is consistent with an adaptation to insulin resistance. Insulin secretion in vitro, examined by perifusion of isolated islets, was not impacted by HSL deficiency. Thus, HSL deficiency results in a moderate impairment of insulin sensitivity in multiple target tissues of the hormone but is compensated by hyperinsulinemia.
  •  
41.
  • Myhrstad, Mari C. W., et al. (författare)
  • Healthy Nordic Diet Modulates the Expression of Genes Related to Mitochondrial Function and Immune Response in Peripheral Blood Mononuclear Cells from Subjects with Metabolic Syndrome-A SYSDIET Sub-Study
  • 2019
  • Ingår i: Molecular Nutrition & Food Research. - : John Wiley & Sons. - 1613-4125 .- 1613-4133. ; 63:13
  • Tidskriftsartikel (refereegranskat)abstract
    • Scope To explore the effect of a healthy Nordic diet on the global transcriptome profile in peripheral blood mononuclear cells (PBMCs) of subjects with metabolic syndrome. Methods and results Subjects with metabolic syndrome undergo a 18/24 week randomized intervention study comparing an isocaloric healthy Nordic diet with an average habitual Nordic diet served as control (SYSDIET study). Altogether, 68 participants are included. PBMCs are obtained before and after intervention and total RNA is subjected to global transcriptome analysis. 1302 probe sets are differentially expressed between the diet groups (p-value < 0.05). Twenty-five of these are significantly regulated (FDR q-value < 0.25) and are mainly involved in mitochondrial function, cell growth, and cell adhesion. The list of 1302 regulated probe sets is subjected to functional analyses. Pathways and processes involved in the mitochondrial electron transport chain, immune response, and cell cycle are downregulated in the healthy Nordic diet group. In addition, gene transcripts with common motifs for 42 transcription factors, including NFR1, NFR2, and NF-kappa B, are downregulated in the healthy Nordic diet group. Conclusion These results suggest that benefits of a healthy diet may be mediated by improved mitochondrial function and reduced inflammation.
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42.
  • Petrus, Paul, et al. (författare)
  • Saturated fatty acids in human visceral adipose tissue are associated with increased 11-beta-hydroxysteroid-dehydrogenase type 1 expression
  • 2015
  • Ingår i: Lipids in Health and Disease. - : Springer Science and Business Media LLC. - 1476-511X. ; 14
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Visceral fat accumulation is associated with metabolic disease. It is therefore relevant to study factors that regulate adipose tissue distribution. Recent data shows that overeating saturated fatty acids promotes greater visceral fat storage than overeating unsaturated fatty acids. Visceral adiposity is observed in states of hypercortisolism, and the enzyme 11-beta-hydroxysteroid-dehydrogenase type 1 (11 beta-hsd1) is a major regulator of cortisol activity by converting inactive cortisone to cortisol in adipose tissue. We hypothesized that tissue fatty acid composition regulates body fat distribution through local effects on the expression of 11 beta-hsd1 and its corresponding gene (HSD11B1) resulting in altered cortisol activity. Findings: Visceral- and subcutaneous adipose tissue biopsies were collected during Roux-en-Y gastric bypass surgery from 45 obese women (BMI; 41 +/- 4 kg/m(2)). The fatty acid composition of each biopsy was measured and correlated to the mRNA levels of HSD11B1. 11 beta-hsd1 protein levels were determined in a subgroup (n = 12) by western blot analysis. Our main finding was that tissue saturated fatty acids (e.g. palmitate) were associated with increased 11 beta-hsd1 gene- and protein-expression in visceral but not subcutaneous adipose tissue. Conclusions: The present study proposes a link between HSD11B1 and saturated fatty acids in visceral, but not subcutaneous adipose tissue. Nutritional regulation of visceral fat mass through HSD11B1 is of interest for the modulation of metabolic risk and warrants further investigation.
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43.
  • Pettersson, Amanda T, et al. (författare)
  • Twist1 in human white adipose tissue and obesity.
  • 2011
  • Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96:1, s. 133-41
  • Tidskriftsartikel (refereegranskat)abstract
    • Twist1 is a transcription factor implicated in the regulation of TNFα signaling and was recently shown to be highly expressed in both human and murine adipose tissue, but its role in obesity is unknown.
  •  
44.
  • Pritchard, Christopher D., et al. (författare)
  • The use of surface modified poly(glycerol-co-sebacic acid) in retinal transplantation
  • 2010
  • Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 31:8, s. 2153-2162
  • Tidskriftsartikel (refereegranskat)abstract
    • Retinal transplantation experiments have advanced considerably during recent years, but remaining diseased photoreceptor cells in the host retina and inner retinal cells in the transplant physically obstruct the development of graft-host neuronal contacts which are required for vision. Recently, we developed methods for the isolation of donor photoreceptor layers in vitro, and the selective removal of host photoreceptors in vivo using biodegradable elastomeric membranes composed of poly(glycerol-co-sebacic acid) (PGS). Here, we report the surface modification of PGS membranes to promote the attachment of photoreceptor layers, allowing the resulting composite to be handled surgically as a single entity. PGS membranes were chemically modified with peptides containing an arginine-glycine-aspartic acid (RGD) extracellular matrix ligand sequence. PGS membranes were also coated with electrospun nanofiber meshes, containing laminin and poly(epsilon-caprolactone) (PCL). Following in vitro co-culture of biomaterial membranes with isolated embryonic retinal tissue, composites were tested for surgical handling and examined with hematoxylin and eosin staining and immunohistochemical markers. Electrospun nanofibers composed of laminin and PCL promoted sufficient cell adhesion for simultaneous transplantation of isolated photoreceptor layers and PGS membranes. Composites developed large populations of recoverin and rhodopsin labeled photoreceptors. Furthermore, ganglion cells, rod bipolar cells and All amacrine cells were absent in co-cultured retinas as observed by neurofilament, PKC and parvalbumin labeling respectively. These results facilitate retinal transplantation experiments in which a composite graft composed of a biodegradable membrane adhered to an immature retina dominated by photoreceptor cells may be delivered in a single surgery, with the possibility of improving graft-host neuronal connections. (C) 2009 Elsevier Ltd. All rights reserved.
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45.
  • Ray, Hind, et al. (författare)
  • The Presence of a Catalytically Inactive Form of Hormone-Sensitive Lipase Is Associated With Decreased Lipolysis in Abdominal Subcutaneous Adipose Tissue of Obese Subjects.
  • 2003
  • Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 52:6, s. 1417-1422
  • Tidskriftsartikel (refereegranskat)abstract
    • Hormone-sensitive lipase (HSL)-L is a key enzyme in the mobilization of fatty acids from triglyceride stores in adipocytes. A shorter variant of HSL (HSL-S) was detected in humans. This one is generated through in-frame skipping of exon 6 during the processing of HSL mRNA and results in a protein devoid of lipase activity. The role of HSL-S is unknown. The aims of this study were to identify both HSL variants in adipose tissue biopsies and to determine if the presence of HSL-S is correlated to the lipolytic capacity of adipocytes. The study was performed in human abdominal subcutaneous adipocytes from two groups of seven obese subjects. In the group of subjects with both HSL proteins (L+S) group, two immunoreactive bands (80 and 88 kDa) were detected, whereas only the 88-kDa protein was detected in the group with only the wild-type HSL-protein (L group). In the L+S group, the HSL activity was 20% lower (P &lt; 0.05) and the (S/S+) HSL mRNA ratio was twofold higher than in the L group (P &lt; 0.05). The maximally lipolytic capacities measured from isolated adipocytes incubated with norepinephrine or other lipolytic agents were 40% lower in the L+S group (P &lt; 0.05). These results suggest that the presence of the truncated HSL protein is associated with an impaired adipocyte lipolysis.
  •  
46.
  •  
47.
  • Rohm, Maria, et al. (författare)
  • An AMP-activated protein kinase-stabilizing peptide ameliorates adipose tissue wasting in cancer cachexia in mice
  • 2016
  • Ingår i: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 22:10, s. 1120-1130
  • Tidskriftsartikel (refereegranskat)abstract
    • Cachexia represents a fatal energy-wasting syndrome in a large number of patients with cancer that mostly results in a pathological loss of skeletal muscle and adipose tissue. Here we show that tumor cell exposure and tumor growth in mice triggered a futile energy-wasting cycle in cultured white adipocytes and white adipose tissue (WAT), respectively. Although uncoupling protein 1 (Ucp1)-dependent thermogenesis was dispensable for tumor-induced body wasting, WAT from cachectic mice and tumor-cell-supernatant-treated adipocytes were consistently characterized by the simultaneous induction of both lipolytic and lipogenic pathways. Paradoxically, this was accompanied by an inactivated AMP-activated protein kinase (Ampk), which is normally activated in peripheral tissues during states of low cellular energy. Ampk inactivation correlated with its degradation and with upregulation of the Ampk-interacting protein Cidea. Therefore, we developed an Ampk-stabilizing peptide, ACIP, which was able to ameliorate WAT wasting in vitro and in vivo by shielding the Cidea-targeted interaction surface on Ampk. Thus, our data establish the Ucp1-independent remodeling of adipocyte lipid homeostasis as a key event in tumor-induced WAT wasting, and we propose the ACIP-dependent preservation of Ampk integrity in the WAT as a concept in future therapies for cachexia.
  •  
48.
  • Rosqvist, Fredrik, et al. (författare)
  • Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans
  • 2014
  • Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 63:7, s. 2356-2368
  • Tidskriftsartikel (refereegranskat)abstract
    • Excess ectopic fat storage is linked to type 2 diabetes. The importance of dietary fat composition for ectopic fat storage in humans is unknown. We investigated liver fat accumulation and body composition during overfeeding saturated (SFA) or polyunsaturated (PUFA) fat. LIPOGAIN was a double-blind, parallel-group, randomized trial. Thirty-nine young and normal-weight individuals were overfed muffins high in SFA (palm oil) or n-6 PUFA (sunflower oil) for 7 weeks. Liver fat, visceral (VAT), subcutaneous abdominal (SAT), and total adipose tissue (TAT), pancreatic fat, and lean tissue was assessed by MRI. Transcriptomics were performed in SAT. Both groups gained similar weight. SFA however markedly increased liver fat compared with PUFA and caused 2-fold larger increase in VAT than PUFA. Conversely, PUFA caused a nearly 3-fold larger increase in lean tissue than SFA. Increase in liver fat directly correlated with changes in plasma SFA and inversely with PUFA. Genes involved in regulating energy dissipation, insulin resistance, body composition and fat cell differentiation in SAT were differentially regulated between diets, and associated with increased PUFA in SAT. In conclusion, overeating SFA promotes hepatic and visceral fat storage whereas excess energy from PUFA may instead promote lean tissue in healthy humans.
  •  
49.
  • Rydén, Mikael, et al. (författare)
  • Lipolysis defect in people with obesity who undergo metabolic surgery
  • 2022
  • Ingår i: Journal of Internal Medicine. - : Wiley-Blackwell Publishing Inc.. - 0954-6820 .- 1365-2796. ; 292:4, s. 667-678
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: Cross-sectional studies demonstrate that catecholamine stimulation of fat cell lipolysis is blunted in obesity. We investigated whether this defect persists after substantial weight loss has been induced by metabolic surgery, and whether it is related to the outcome.DESIGN/METHODS: Patients with obesity not able to successfully reduce body weight by conventional means (n = 126) were investigated before and 5 years after Roux-en-Y gastric bypass surgery (RYGB). They were compared with propensity-score matched subjects selected from a control group (n = 1017), and with the entire group after adjustment for age, sex, body mass index (BMI), fat cell volume and other clinical parameters. Catecholamine-stimulated lipolysis (glycerol release) was investigated in isolated fat cells using noradrenaline (natural hormone) or isoprenaline (synthetic beta-adrenoceptor agonist).RESULTS: Following RYGB, BMI was reduced from 39.9 (37.5-43.5) (median and interquartile range) to 29.5 (26.7-31.9) kg/m2 (p < 0.0001). The post-RYGB patients had about 50% lower lipolysis rates compared with the matched and total series of controls (p < 0.0005). Nordrenaline activation of lipolysis at baseline was associated with the RYGB effect; those with high lipolysis activation (upper tertile) lost 30%-45% more in body weight, BMI or fat mass than those with low (bottom tertile) initial lipolysis activation (p < 0.0007).CONCLUSION: Patients with obesity requiring metabolic surgery have impaired ability of catecholamines to stimulate lipolysis, which remains despite long-term normalization of body weight by RYGB. Furthermore, preoperative variations in the ability of catecholamines to activate lipolysis may predict the long-term reduction in body weight and fat mass.
  •  
50.
  • Stenvall, Jörgen, et al. (författare)
  • Selenoprotein TRXR-1 and GSR-1 are essential for removal of old cuticle during molting in Caenorhabditis elegans
  • 2011
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:3, s. 1064-1069
  • Tidskriftsartikel (refereegranskat)abstract
    • Selenoproteins, in particular thioredoxin reductase, have been implicated in countering oxidative damage occurring during aging but the molecular functions of these proteins have not been extensively investigated in different animal models. Here we demonstrate that TRXR-1 thioredoxin reductase, the sole selenoprotein in Caenorhabditis elegans, does not protect against acute oxidative stress but functions instead together with GSR-1 glutathione reductase to promote the removal of old cuticle during molting. We show that the oxidation state of disulfide groups in the cuticle is tightly regulated during the molting cycle, and that when trxr-1 and gsr-1 function is reduced, disulfide groups in the cuticle remain oxidized. A selenocysteine-to-cysteine TRXR-1 mutant fails to rescue molting defects. Furthermore, worms lacking SELB-1, the C. elegans homolog of Escherichia coli SelB or mammalian EFsec, a translation elongation factor known to be specific for selenocysteine in E. coli, fail to incorporate selenocysteine, and display the same phenotype as those lacking trxr-1. Thus, TRXR-1 function in the reduction of old cuticle is strictly selenocysteine dependent in the nematode. Exogenously supplied reduced glutathione reduces disulfide groups in the cuticle and induces apolysis, the separation of old and new cuticle, strongly suggesting that molting involves the regulated reduction of cuticle components driven by TRXR-1 and GSR-1. Using dauer larvae, we demonstrate that aged worms have a decreased capacity to molt, and decreased expression of GSR-1. Together, our results establish a function for the selenoprotein TRXR-1 and GSR-1 in the removal of old cuticle from the surface of epidermal cells.
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