| 1. |
- Axling, Ulrika, et al.
(författare)
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Rose hip exerts antidiabetic effects via a mechanism involving downregulation of the hepatic lipogenic program
- 2011
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Ingår i: American Journal of Physiology: Endocrinology and Metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 300:1, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- Andersson U, Henriksson E, Strom K, Alenfall J, Goransson O, Holm C. Rose hip exerts antidiabetic effects via a mechanism involving downregulation of the hepatic lipogenic program. Am J Physiol Endocrinol Metab 300: E111-E121, 2011. First published October 19, 2010; doi:10.1152/ajpendo.00268.2010.-The aim of this study was to investigate the metabolic effects of a dietary supplement of powdered rose hip to C57BL/6J mice fed a high-fat diet (HFD). Two different study protocols were used; rose hip was fed together with HFD to lean mice for 20 wk (prevention study) and to obese mice for 10 wk (intervention study). Parameters related to obesity and glucose tolerance were monitored, and livers were examined for lipids and expression of genes and proteins related to lipid metabolism and gluconeogenesis. A supplement of rose hip was capable of both preventing and reversing the increase in body weight and body fat mass imposed by a HFD in the C57BL/6J mouse. Oral and intravenous glucose tolerance tests together with lower basal levels of insulin and glucose showed improved glucose tolerance in mice fed a supplement of rose hip compared with control mice. Hepatic lipid accumulation was reduced in mice fed rose hip compared with control, and the expression of lipogenic proteins was downregulated, whereas AMP-activated protein kinase and other proteins involved in fatty acid oxidation were unaltered. Rose hip intake lowered total plasma cholesterol as well as the low-density lipoprotein-to-high-density lipoprotein ratio via a mechanism not involving altered gene expression of sterol regulatory element-binding protein 2 or 3-hydroxymethylglutaryl-CoA reductase. Taken together, these data show that a dietary supplement of rose hip prevents the development of a diabetic state in the C57BL/6J mouse and that downregulation of the hepatic lipogenic program appears to be at least one mechanism underlying the antidiabetic effect of rose hip.
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| 2. |
- Berggreen, Christine, et al.
(författare)
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cAMP-elevation mediated by β-adrenergic stimulation inhibits salt-inducible kinase (SIK) 3 activity in adipocytes.
- 2012
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 24:9, s. 1863-1871
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Tidskriftsartikel (refereegranskat)abstract
- Salt-inducible kinase (SIK) 3 is a virtually unstudied, ubiquitously expressed serine/threonine kinase, belonging to the AMP-activated protein kinase (AMPK)-related family of kinases, all of which are regulated by LKB1 phosphorylation of a threonine residue in their activation (T)-loops. Findings in adrenal cells have revealed a role for cAMP in the regulation of SIK1, and recent findings suggest that insulin can regulate an SIK isoform in Drosophila. As cAMP has important functions in adipocytes, mainly in the regulation of lipolysis, we have evaluated a potential role for cAMP, as well as for insulin, in the regulation of SIK3 in these cells. We establish that raised cAMP levels in response to forskolin and the β-adrenergic receptor agonist CL 316,243 induce a phosphorylation of SIK3 in HEK293 cells and primary adipocytes. This phosphorylation coincides with increased 14-3-3 binding to SIK3 in these cell types. Our findings also show that cAMP-elevation results in reduced SIK3 activity in adipocytes. Phosphopeptide mapping and site-directed mutagenesis reveal that the cAMP-mediated regulation of SIK3 appears to depend on three residues, T469, S551 and S674, that all contribute to some extent to the cAMP-induced phosphorylation and 14-3-3-binding. As the cAMP-induced regulation can be reversed with the protein kinase A (PKA) inhibitor H89, and a role for other candidate kinases, including PKB and RSK, could be excluded, we believe that PKA is the kinase responsible for SIK3 regulation in response to elevated cAMP levels. Our findings of cAMP-mediated regulation of SIK3 suggest that SIK3 may mediate some of the effects of this important second messenger in adipocytes.
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| 3. |
- Gormand, Amelie, et al.
(författare)
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Regulation of AMP-activated protein kinase by LKB1 and CaMKK in adipocytes.
- 2011
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Ingår i: Journal of Cellular Biochemistry. - : Wiley. - 0730-2312. ; 112, s. 1364-1375
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Tidskriftsartikel (refereegranskat)abstract
- AMP-activated protein kinase (AMPK) is a serine/threonine kinase that regulates cellular and whole body energy homeostasis. In adipose tissue, activation of AMPK has been demonstrated in response to a variety of extracellular stimuli. However, the upstream kinase that activates AMPK in adipocytes remains elusive. Previous studies have identified LKB1 as a major AMPK kinase in muscle, liver and other tissues. In certain cell types, Ca(2+) /Calmodulin-dependent protein kinase kinase (CaMKK) β has been shown to activate AMPK in response to increase of intracellular Ca(2+) levels. Our aim was to investigate if LKB1 and/or CaMKK function as AMPK kinases in adipocytes. We used adipose tissue and isolated adipocytes from mice in which the expression of LKB1 was reduced to 10-20% of that of wild-type (LKB1 hypomorphic mice). We show that adipocytes from LKB1 hypomorphic mice display a 40% decrease in basal AMPK activity and a decrease of AMPK activity in the presence of the AMPK activator phenformin. We also demonstrate that stimulation of 3T3L1 adipocytes with intracellular [Ca(2+) ]-raising agents results in an activation of the AMPK pathway. The inhibition of CaMKK isoforms, particularly CaMKKβ, by the inhibitor STO-609 or by siRNAs, blocked Ca(2+) -, but not phenformin-, AICAR or forskolin-induced activation of AMPK, indicating that CaMKK activated AMPK in response to Ca(2+) . Collectively, we show that LKB1 is required to maintain normal AMPK-signalling in non-stimulated adipocytes and in the presence of phenformin. In addition, we demonstrate the existence of a Ca(2+) /CaMKK signalling pathway that can also regulate the activity of AMPK in adipocytes. J. Cell. Biochem. © 2011 Wiley-Liss, Inc.
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| 4. |
- Henriksson, Emma
(författare)
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LKB1 signaling pathways in adipocytes - Focus on the AMPK-related kinase SIK2
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adipose tissue does not only store and release energy in response to hormones, it is also known as an endocrine organ, secreting important factors and hormones that influence for example appetite and insulin sensitivity. The association of type 2 diabetes with obesity has been known for quite some time. Understanding the cellular mechanisms of adipocyte function is of great importance in understanding when and why excess adipose tissue becomes dangerous. Signal transduction pathways used for example by hormones to control cellular function, often consists of protein kinases. These enzymes constitute a large part of our genome and are crucial for the regulation of almost all cellular processes. AMP-activated protein kinase (AMPK) is known for its various roles in the regulation of metabolism and is activated when cellular energy levels are low, which is reflected in increased levels of AMP. In addition to AMPK, some of its related kinases, including the salt-inducible kinases (SIKs), have also been implicated in the regulation of metabolism. LKB1 is known as a tumor suppressor and was recently found to be required for the activity of AMPK and most of its related kinases, phosphorylating a specific threonine residue in their activation loop. The aim of this thesis was to investigate the regulation of LKB1 signaling pathways in adipocytes, with a focus on SIK2, which is of particulate interest in adipocytes due to its high abundance in these cells. We show that AMPK activity is regulated by LKB1 and CaMKK in adipocytes and describe a regulation of SIK2 and SIK3 by cAMP/PKA signaling. The PKA-dependent phosphorylations of SIK2 and SIK3 were identified and shown to mediate a binding to 14-3-3 proteins, resulting in a re-localization from a particulate fraction to the cytosol, and a decrease in activity, respectively. In addition, we suggest that the transcriptional regulators CREB-regulated transcription co-activator (CRTC) 2, -3 and histone deacetylase (HDAC) 4, are substrates of SIK2 in adipocytes. Based on our findings, we hypothesize that SIK isoforms take part in transcriptional regulation of genes involved in lipid and glucose metabolism in adipocytes, through their action on HDAC4, CRTC2 and CRTC3, and potentially also other transcriptional regulators. We also identified PP2A as an interacting partner of SIK2 in adipocytes and future studies will further evaluate the importance and function of this interaction. In conclusion, this thesis has revealed regulation of AMPK, SIK2 and SIK3, important for adipocyte function and provided preliminary data connecting SIK2 to both lipid and glucose metabolism in adipocytes.
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| 5. |
- Henriksson, Emma, et al.
(författare)
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The AMPK-related kinase SIK2 is regulated by cAMP via phosphorylation at Ser(358) in adipocytes
- 2012
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Ingår i: Biochemical Journal. - 0264-6021. ; 444, s. 503-514
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Tidskriftsartikel (refereegranskat)abstract
- SIK2 (salt-inducible kinase 2) is a member of the AMPK (AMP-activated protein kinase) family of kinases and is highly expressed in adipocytes. We investigated the regulation of SIK2 in adipocytes in response to cellular stimuli with relevance for adipocyte function and/or AMPK signalling. None of the treatments, including insulin, cAMP inducers or AICAR (5-amino-4-imidazolecarboxamide riboside), affected SIK2 activity towards peptide or protein substrates in vitro. However, stimulation with the cAMP-elevating agent forskolin and the beta-adrenergic receptor agonist CL 316,243 resulted in a PKA (protein kinase A)-dependent phosphorylation and 14-3-3 binding of SIK2. Phosphopeptide mapping of SIK2 revealed several sites phosphorylated in response to cAMP induction, including Ser(358). Site-directed mutagenesis demonstrated that phosphorylation of See(358), but not the previously reported PKA site See(587), was required for 14-3-3 binding. Immunocytochemistry illustrated that the localization of exogenously expressed SIK2 in HEK (human embryonic kidney)-293 cells was exclusively cytosolic and remained unchanged after cAMP elevation. Fractionation of adipocytes, however, revealed a significant increase of wild-type, but not Ser358Ala, HA (haemagglutinin) SIK2 in the cytosol and a concomitant decrease in a particulate fraction after CL 316,243 treatment. This supports a phosphorylation-dependent relocalization in adipocytes. We hypothesize that regulation of SIK2 by cAMP could play a role for the critical effects of this second messenger on lipid metabolism in adipocytes.
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| 6. |
- Jungebluth, Philipp, et al.
(författare)
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Tracheobronchial transplantation with a stem-cell-seeded bioartificial nanocomposite : a proof-of-concept study
- 2011
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 378:9808, s. 1997-2004
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Tidskriftsartikel (refereegranskat)abstract
- Background Tracheal tumours can be surgically resected but most are an inoperable size at the time of diagnosis; therefore, new therapeutic options are needed. We report the clinical transplantation of the tracheobronchial airway with a stem-cell-seeded bioartificial nanocomposite. Methods A 36-year-old male patient, previously treated with debulking surgery and radiation therapy, presented with recurrent primary cancer of the distal trachea and main bronchi. After complete tumour resection, the airway was replaced with a tailored bioartificial nanocomposite previously seeded with autologous bone-marrow mononuclear cells via a bioreactor for 36 h. Postoperative granulocyte colony-stimulating factor filgrastim (10 mu g/kg) and epoetin beta (40 000 UI) were given over 14 days. We undertook flow cytometry, scanning electron microscopy, confocal microscopy epigenetics, multiplex, miRNA, and gene expression analyses. Findings We noted an extracellular matrix-like coating and proliferating cells including a CD105+ subpopulation in the scaffold after the reseeding and bioreactor process. There were no major complications, and the patient was asymptomatic and tumour free 5 months after trans plantation. The bioartificial nanocomposite has patent anastomoses, lined with a vascularised neomucosa, and was partly covered by nearly healthy epithelium. Post-operatively, we detected a mobilisation of peripheral cells displaying increased mesenchymal stromal cell phenotype, and upregulation of epoetin receptors, antiapoptotic genes, and miR-34 and miR-449 biomarkers. These findings, together with increased levels of regenerative-associated plasma factors, strongly suggest stem-cell homing and cell-mediated wound repair, extracellular matrix remodelling, and neovascularisation of the graft. Interpretation Tailor-made bioartificial scaffolds can be used to replace complex airway defects. The bioreactor reseeding process and pharmacological-induced site-specific and graft-specific regeneration and tissue protection are key factors for successful clinical outcome.
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| 7. |
- Wichardt, Emma, et al.
(författare)
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Rhabdomyolysis/myoglobinemia and NSAID during 48-hours ultra-endurance exercise (adventure racing)
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 111:7, s. 1541-1544
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To determine if rhabdomyolysis with myoglobinemia exists during a 48+ hour adventure race and if there is a correlation with NSAID use, race time and perceived pain or exertion. Method: Blood samples for analyses of myoglobin (Mb) were collected, and perception of exertion and pain registered on the Borg-RPE and CR scales, from 20 subjects (3 female, 17 male) Pre, Mid and Post race. Subjects were asked about NSAID use at each sampling and within 12 hours pre race. Result: A significant rise in Mb was observed throughout the race, with the NSAID group (n=6) having significantly lower Mb-Post than the no-NSAID group (n=14). High Mb-Pre and Post correlated to shorter race time and high Mb-Pre to lower Pain-Post. Race time also correlated to NSAID use, with the NSAID group having significantly longer race time than the no-NSAID group. Conclusion: Rhabdomyolysis with myoglobinemia, which might be reduced with NSAID use, exists during a 48+ hour adventure race. Indications that high Mb-levels correlate with shorter race time and less pain, and the reasons for the NSAID groups longer race time, need further investigation.
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| 8. |
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