| 1. |
- Angerfors, Annelie, et al.
(författare)
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Proteomic profiling identifies novel inflammation-related plasma proteins associated with ischemic stroke outcome
- 2023
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Ingår i: Journal of Neuroinflammation. - 1742-2094. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The inflammatory response to cerebral ischemia is complex; however, most clinical studies of stroke outcome focus on a few selected proteins. We, therefore, aimed to profile a broad range of inflammation-related proteins to: identify proteins associated with ischemic stroke outcome that are independent of established clinical predictors; identify proteins subsets for outcome prediction; and perform sex and etiological subtype stratified analyses.Methods Acute-phase plasma levels of 65 inflammation-related proteins were measured in 534 ischemic stroke cases. Logistic regression was used to estimate associations to unfavorable 3-month functional outcome (modified Rankin Scale score > 2) and LASSO regressions to identify proteins with independent effects.Results Twenty proteins were associated with outcome in univariable models after correction for multiple testing (FDR < 0.05), and for 5 the association was independent of clinical variables, including stroke severity (TNFSF14 [LIGHT], OSM, SIRT2, STAMBP, and 4E-BP1). LASSO identified 9 proteins that could best separate favorable and unfavorable outcome with a predicted diagnostic accuracy (AUC) of 0.81; three associated with favorable (CCL25, TRAIL [TNFSF10], and Flt3L) and 6 with unfavorable outcome (CSF-1, EN-RAGE [S100A12], HGF, IL-6, OSM, and TNFSF14). Finally, we identified sex- and etiologic subtype-specific associations with the best discriminative ability achieved for cardioembolic, followed by cryptogenic stroke.Conclusions We identified candidate blood-based protein biomarkers for post-stroke functional outcome involved in, e.g., NLRP3 inflammasome regulation and signaling pathways, such as TNF, JAK/STAT, MAPK, and NF-kappa B. These proteins warrant further study for stroke outcome prediction as well as investigations into the putative causal role for stroke outcome.
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| 2. |
- Asif, Muhammad H, et al.
(författare)
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Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
- 2010
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 25:10, s. 2205-2211
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration. (C) 2010 Elsevier B.V. All rights reserved.
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| 3. |
- Asif, Muhammad H., et al.
(författare)
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Growth and Structure of ZnO Nanorods on a Sub-Micrometer Glass Pipette and Their Application as Intracellular Potentiometric Selective Ion Sensors
- 2010
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 3, s. 4657-4667
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the growth and structure of ZnO nanorods on a sub-micrometer glass pipette and their application as an intracellular selective ion sensor. Highly oriented, vertical and aligned ZnO nanorods were grown on the tip of a borosilicate glass capillary (0.7 μm in diameter) by the low temperature aqueous chemical growth (ACG) technique. The relatively large surface-to-volume ratio of ZnO nanorods makes them attractive for electrochemical sensing. Transmission electron microscopy studies show that ZnO nanorods are single crystals and grow along the crystal’s c-axis. The ZnO nanorods were functionalized with a polymeric membrane for selective intracellular measurements of Na +. The membrane-coated ZnO nanorods exhibited a Na+-dependent electrochemical potential difference versus an Ag/AgCl reference micro-electrode within a wide concentration range from 0.5 mM to 100 mM. The fabrication of functionalized ZnO nanorods paves the way to sense a wide range of biochemical species at the intracellular level.
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| 4. |
- Brännmark, Cecilia, et al.
(författare)
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Adiponectin is secreted via caveolin 1-dependent mechanisms in white adipocytes
- 2020
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Ingår i: Journal of Endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 247:1, s. 25-38
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Tidskriftsartikel (refereegranskat)abstract
- Here we have investigated the role of the protein caveolin 1 (Cav1) and caveolae in the secretion of the white adipocyte hormone adiponectin. Using mouse primary subcutaneous adipocytes genetically depleted of Cav1, we show that the adiponectin secretion, stimulated either adrenergically or by insulin, is abrogated while basal (unstimulated) release of adiponectin is elevated. Adiponectin secretion is similarly affected in wildtype mouse and human adipocytes where the caveolae structure was chemically disrupted. The altered ex vivo secretion in adipocytes isolated from Cav1 null mice is accompanied by lowered serum levels of the high-molecular weight (HMW) form of adiponectin, whereas the total concentration of adiponectin is unaltered. Interestingly, levels of HMW adiponectin are maintained in adipose tissue from Cav1-depleted mice, signifying that a secretory defect is present. The gene expression of key regulatory proteins known to be involved in cAMP/adrenergically triggered adiponectin exocytosis (the beta-3-adrenergic receptor and exchange protein directly activated by cAMP) remains intact in Cav1 null adipocytes. Microscopy and fractionation studies indicate that adiponectin vesicles do not co-localise with Cav1 but that some vesicles are associated with a specific fraction of caveolae. Our studies propose that Cav1 has an important role in secretion of HMW adiponectin, even though adiponectin-containing vesicles are not obviously associated with this protein. We suggest that Cav1, and/or the caveolae domain, is essential for the organisation of signalling pathways involved in the regulation of HMW adiponectin exocytosis, a function that is disrupted in Cav1/caveolae-depleted adipocytes.
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| 5. |
- Brännmark, Cecilia, et al.
(författare)
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FIND Stroke Recovery Study (FIND): rationale and protocol for a longitudinal observational cohort study of trajectories of recovery and biomarkers poststroke
- 2023
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Ingår i: Bmj Open. - 2044-6055. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- ntroduction Comprehensive studies mapping domain-specific trajectories of recovery after stroke and biomarkers reflecting these processes are scarce. We, therefore, initiated an exploratory prospective observational study of stroke cases with repeated evaluation, the FIND Stroke Recovery Study. We aim to capture trajectories of recovery from different impairments, including cognition, in combination with broad profiling of blood and imaging biomarkers of the recovery. Methods and analysis We recruit individuals with first-ever stroke at the stroke unit at the Sahlgrenska University Hospital, Sweden, to FIND. The inclusion started early 2018 and we aim to enrol minimum 500 patients. Neurological and cognitive impairments across multiple domains are assessed using validated clinical assessment methods, advanced neuroimaging is performed and blood samples for biomarker measuring (protein, RNA and DNA) at inclusion and follow-up visits at 3 months, 6 months, 1 year, 2 years and 5 years poststroke. At baseline and at each follow-up visit, we also register clinical variables known to influence outcomes such as prestroke functioning, stroke severity, acute interventions, rehabilitation, other treatments, socioeconomic status, infections (including COVID-19) and other comorbidities. Recurrent stroke and other major vascular events are identified continuously in national registers. Ethics and dissemination FIND composes a unique stroke cohort with detailed phenotyping, repetitive assessments of outcomes across multiple neurological and cognitive domains and patient-reported outcomes as well as blood and imaging biomarker profiling. Ethical approval for the FIND study has been obtained from the Regional Ethics Review Board in Gothenburg and the Swedish Ethics Review Board. The results of this exploratory study will provide novel data on the time course of recovery and biomarkers after stroke. The description of this protocol will inform the stroke research community of our ongoing study and facilitate comparisons with other data sets.
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| 6. |
- Brännmark, Cecilia, 1983-
(författare)
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Insulin Signaling in Human Adipocytes a Systems Biology Approach
- 2012
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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. |
- Brännmark, Cecilia, et al.
(författare)
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Insulin Signaling in Type 2 Diabetes : Experimental and Modeling Analyses Reveal Mechanisms of Insulin Resistance in Human Adipocytes
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:14, s. 9867-9880
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Tidskriftsartikel (refereegranskat)abstract
- Type 2 diabetes originates in an expanding adipose tissue that for unknown reasons becomes insulin resistant. Insulin resistance reflects impairments in insulin signaling, but mechanisms involved are unclear because current research is fragmented. We report a systems-level mechanistic understanding of insulin resistance in humans. We developed a dynamic mathematical model of insulin signaling – normally and in diabetes – based on quantitative steady-state and dynamic time-course data on signaling intermediaries in human mature adipocytes. At the core of insulin resistance is attenuation of a positive feedback from mammalian target of rapamycin in complex with raptor (mTORC1) to the insulin receptor substrate-1 (IRS1), which explains reduced sensitivity and signal strength throughout the signaling network. We demonstrate the potential of the model for identification of drug targets, e.g. increasing the feedback restores insulin signaling. Our findings suggest that insulin resistance in an expanded adipose tissue results from cell growth restriction to prevent cell necrosis.
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| 8. |
- Brännmark, Cecilia, et al.
(författare)
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Mathematical modeling of white adipocyte exocytosis predicts adiponectin secretion and quantifies the rates of vesicle exo- and endocytosis
- 2017
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Ingår i: Journal of Biological Chemistry. - : AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC. - 0021-9258 .- 1083-351X. ; 292:49, s. 20032-20043
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Tidskriftsartikel (refereegranskat)abstract
- Adiponectin is a hormone secreted from white adipocytes and takes part in the regulation of several metabolic processes. Although the pathophysiological importance of adiponectin has been thoroughly investigated, the mechanisms controlling its release are only partly understood. We have recently shown that adiponectin is secreted via regulated exocytosis of adiponectin-containing vesicles, that adiponectin exocytosis is stimulated by cAMP-dependent mechanisms, and that Ca2+ and ATP augment the cAMP-triggered secretion. However, much remains to be discovered regarding the molecular and cellular regulation of adiponectin release. Here, we have used mathematical modeling to extract detailed information contained within our previously obtained high-resolution patch-clamp time-resolved capacitance recordings to produce the first model of adiponectin exocytosis/secretion that combines all mechanistic knowledge deduced from electrophysiological experimental series. This model demonstrates that our previous understanding of the role of intracellular ATP in the control of adiponectin exocytosis needs to be revised to include an additional ATP-dependent step. Validation of the model by introduction of data of secreted adiponectin yielded a very close resemblance between the simulations and experimental results. Moreover, we could show that Ca2+-dependent adiponectin endocytosis contributes to the measured capacitance signal, and we were able to predict the contribution of endocytosis to the measured exocytotic rate under different experimental conditions. In conclusion, using mathematical modeling of published and newly generated data, we have obtained estimates of adiponectin exo- and endocytosis rates, and we have predicted adiponectin secretion. We believe that our model should have multiple applications in the study of metabolic processes and hormonal control thereof.
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| 9. |
- Bäck, Karolina, et al.
(författare)
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Differential effects of IGF-I, IGF-II and insulin in human preadipocytes and adipocytes - Role of insulin and IGF-I receptors
- 2011
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier Science B.V., Amsterdam.. - 0303-7207 .- 1872-8057. ; 339:02-jan, s. 130-135
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Tidskriftsartikel (refereegranskat)abstract
- We compared insulin and IGF effects in adipocytes expressing IR (insulin receptors), and preadipocytes expressing IR and IGF-IR (IGF-I receptors). Treatment of adipocytes with insulin, IGF-II or IGF-I resulted in phosphorylation of IR. Order of potency was insulin greater thanIGF-IIgreater than IGF-I. In preadipocytes IR, IGF-IR and insulin/IGF-I hybrid receptors (HR) were detected. Treatment of preadipocytes with IGF-I and IGF-II 10(-8) M resulted in activation of IGF-IR and IR whereas insulin was more potent in activating IR, with no effect on IGF-IR. In adipocytes glucose transport was 100-fold more sensitive to insulin than to IGFs and the maximal effect was higher with insulin. In preadipocytes glucose accumulation and DNA synthesis was equally sensitive to insulin and IGFs but the maximal effect was higher with IGF-I. In conclusion, insulin and IGF-I activate their cognate receptors and IGF-I also HR. IGF-II activates IR, IGF-IR and HR. Insulin and IGF-I are partial agonists to each others receptors.
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| 10. |
- El Hachmane, Michael, et al.
(författare)
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Extracellular ATP activates store-operated Ca2+ entry in white adipocytes: functional evidence for STIM1 and ORAI1
- 2018
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Ingår i: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 475, s. 691-704
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we have applied ratiometric measurements of intracellular Ca2+ concentrations ([Ca2+](i)) to show that extracellularly applied ATP (adenosine triphosphate) (100 mM) stimulates store-operated Ca2+ entry (SOCE) in 3T3-L1 adipocytes. ATP produced a rapid increase in [Ca2+](i) consisting of an initial transient elevation followed by a sustained elevated phase that could be observed only in the presence of extracellular Ca2+. Gene expression data and [Ca2+](i) recordings with uridine-50-triphosphate or with the phospholipase C (PLC) inhibitor U73122 demonstrated the involvement of purinergic P2Y2 receptors and the PLC/inositol trisphosphate pathway. The [Ca2+](i) elevation produced by reintroduction of a Ca2+-containing intracellular solution to adipocytes exposed to ATP in the absence of Ca2+ was diminished by known SOCE antagonists. The chief molecular components of SOCE, the stromal interaction molecule 1 (STIM1) and the calcium release-activated calcium channel protein 1 (ORAI1), were detected at the mRNA and protein level. Moreover, SOCE was largely diminished in cells where STIM1 and/or ORAI1 had been silenced by small interfering (si) RNA. We conclude that extracellular ATP activates SOCE in white adipocytes, an effect predominantly mediated by STIM1 and ORAI1.
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| 11. |
- Fulati, Alimujiang, 1981-, et al.
(författare)
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An intracellular glucose biosensor based on nanoflake ZnO
- 2010
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 150:2, s. 673-680
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this study, an improved potentiometric intracellular glucose biosensor was fabricated with immobilization of glucose oxidase on a ZnO nanoporous material. The ZnO nanoporous material with a wall thickness around 200 nm was grown on the tip of a borosilicate glass capillary and used as a selective intracellular glucose sensor for the measurement of glucose concentrations in human adipocytes and frog oocytes. The results showed a fast response within 4 s and a linear glucosedependent electrochemical response over a wide range of glucose concentration (500 nM-10 mM). The measurements of intracellular glucose concentrations with our biosensor were consistent with the values of intracellular glucose concentrations reported in the literature. The sensor also demonstrated its capability by detecting an increase in the intracellular glucose concentration induced by insulin. We found that the ZnO nanoporous material provides sensitivity as high as 1.8 times higher than that obtained using ZnO nanorods under the same conditions. Moreover, the fabrication method in our experiment is simple and the excellent performance of the developed nanosensor in sensitivity, stability, selectivity, reproducibility and anti-interference was achieved. All these advantageous features of this intracellular glucose biosensor based on functionalised ZnO nanoporous material compared to ZnO nanorods demonstrate a promising way of enhancing glucose biosensor performance to measure reliable intracellular glucose concentrations within single living cells.
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| 12. |
- Nyman, Elin, et al.
(författare)
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A Hierarchical Whole-body Modeling Approach Elucidates the Link between in Vitro Insulin Signaling and in Vivo Glucose Homeostasis
- 2011
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 286:29, s. 26028-26041
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Tidskriftsartikel (refereegranskat)abstract
- Type 2 diabetes is a metabolic disease that profoundly affects energy homeostasis. The disease involves failure at several levels and subsystems and is characterized by insulin resistance in target cells and tissues (i.e. by impaired intracellular insulin signaling). We have previously used an iterative experimental-theoretical approach to unravel the early insulin signaling events in primary human adipocytes. That study, like most insulin signaling studies, is based on in vitro experimental examination of cells, and the in vivo relevance of such studies for human beings has not been systematically examined. Herein, we develop a hierarchical model of the adipose tissue, which links intracellular insulin control of glucose transport in human primary adipocytes with whole-body glucose homeostasis. An iterative approach between experiments and minimal modeling allowed us to conclude that it is not possible to scale up the experimentally determined glucose uptake by the isolated adipocytes to match the glucose uptake profile of the adipose tissue in vivo. However, a model that additionally includes insulin effects on blood flow in the adipose tissue and GLUT4 translocation due to cell handling can explain all data, but neither of these additions is sufficient independently. We also extend the minimal model to include hierarchical dynamic links to more detailed models (both to our own models and to those by others), which act as submodules that can be turned on or off. The resulting multilevel hierarchical model can merge detailed results on different subsystems into a coherent understanding of whole-body glucose homeostasis. This hierarchical modeling can potentially create bridges between other experimental model systems and the in vivo human situation and offers a framework for systematic evaluation of the physiological relevance of in vitro obtained molecular/cellular experimental data.
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| 13. |
- Nyman, Elin, et al.
(författare)
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A Single Mechanism Can Explain Network-wide Insulin Resistance in Adipocytes from Obese Patients with Type 2 Diabetes
- 2014
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 289:48, s. 33215-33230
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Tidskriftsartikel (refereegranskat)abstract
- The response to insulin is impaired in type 2 diabetes. Much information is available about insulin signaling, but understanding of the cellular mechanisms causing impaired signaling and insulin resistance is hampered by fragmented data, mainly obtained from different cell lines and animals. We have collected quantitative and systems-wide dynamic data on insulin signaling in primary adipocytes and compared cells isolated from healthy and diabetic individuals. Mathematical modeling and experimental verification identified mechanisms of insulin control of the MAPKs ERK1/2. We found that in human adipocytes, insulin stimulates phosphorylation of the ribosomal protein S6 and hence protein synthesis about equally via ERK1/2 and mTORC1. Using mathematical modeling, we examined the signaling network as a whole and show that a single mechanism can explain the insulin resistance of type 2 diabetes throughout the network, involving signaling both through IRS1, PKB, and mTOR and via ERK1/2 to the nuclear transcription factor Elk1. The most important part of the insulin resistance mechanism is an attenuated feedback from the protein kinase mTORC1 to IRS1, which spreads signal attenuation to all parts of the insulin signaling network. Experimental inhibition of mTORC1 using rapamycin in adipocytes from non-diabetic individuals induced and thus confirmed the predicted network-wide insulin resistance.
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| 14. |
- Nyman, Elin, et al.
(författare)
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The insulin-signaling network in human adipocytes, normally and in diabetes : role of signaling through ERK1/2
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Insulin acutely controls metabolism in adipocytes, but also nuclear transcription through the “mitogenic” signaling pathway mediated by Map-kinases ERK1/2 (ERK). The cellular metabolic response to insulin is attenuated in insulin resistance and type 2 diabetes, but whether this involves also signaling through ERK is unclear. Based on experimental data from primary mature human adipocytes from diabetic and nondiabetic individuals, we demonstrate a network-wide, model-based analysis of insulin signaling through ERK to phosphorylation of transcription factor Elk1 integrated with signaling for “metabolic” control. We use minimal modeling to analyze the idiosyncratic phosphorylation dynamics of ERK, i.e. a slow phosphorylation response that returns to basal in response to insulin, and conclude that sequestration of ERK is the simplest explanation to data. We also demonstrate a significant cross-talk between ERK and mTORC1 signaling to ribosomal protein S6 for control of protein synthesis. A reduced sensitivity and reduced maximal phosphorylation of ERK in response to insulin in the diabetic state can be explained by the same mechanisms that generate insulin resistance in the control of metabolism.
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| 15. |
- Paul, Alexandra, 1988, et al.
(författare)
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Comparing lipid remodeling of brown adipose tissue, white adipose tissue, and liver after one-week high fat diet intervention with quantitative Raman microscopy
- 2023
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Ingår i: Journal of Cellular Biochemistry. - : Wiley. - 0730-2312 .- 1097-4644. ; 124:3, s. 382-395
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Tidskriftsartikel (refereegranskat)abstract
- Brown adipose tissue (BAT) consists of highly metabolically active adipocytes that catabolize nutrients to produce heat. Playing an active role in triacylglycerol (TAG) clearance, research has shown that dietary fatty acids can modulate the TAG chemistry deposition in BAT after weeks-long dietary intervention, similar to what has been shown in white adipose tissue (WAT). Our objective was to compare the influence of sustained, nonchronic dietary intervention (a 1-week interval) on WAT and interscapular BAT lipid metabolism and deposition in situ. We use quantitative, label-free chemical microscopy to show that 1 week of high fat diet (HFD) intervention results in dramatically larger lipid droplet (LD) growth in BAT (and liver) compared to LD growth in inguinal WAT (IWAT). Moreover, BAT showed lipid remodeling as increased unsaturated TAGs in LDs, resembling the dietary lipid composition, while WAT (and liver) did not show lipid remodeling on this time scale. Concurrently, expression of genes involved in lipid metabolism, particularly desaturases, was reduced in BAT and liver from HFD-fed mice after 1 week. Our data show that BAT lipid chemistry remodels exceptionally fast to dietary lipid intervention compared WAT, which further points towards a role in TAG clearance.
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| 16. |
- Paul, A., et al.
(författare)
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Quantitative Mapping of Triacylglycerol Chain Length and Saturation Using Broadband CARS Microscopy
- 2019
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495. ; 116:12, s. 2346-2355
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Tidskriftsartikel (refereegranskat)abstract
- Lipid droplets (LDs), present in many cell types, are highly dynamic organelles that store neutral lipids, primarily triacylglycerols (TAGs). With the discovery of new LD functions (e.g., in immune response, protein clearage, and occurrence with disease), new methods to study LD chemical composition in situ are necessary. We present an approach for in situ, quantitative TAG analysis using label-free, coherent Raman microscopy that allows deciphering LD TAG composition in different biochemically complex samples with submicrometer spatial resolution. Employing a set of standard TAGs, we generate a spectral training matrix capturing the variation caused in Raman-like spectra by TAG backbone, chain length, and number of double bonds per chain, as well as the presence of proteins or other diluting molecules. Comparing our fitting approach to gas chromatography measurements for mixtures of standard TAGs and food oils, we find the root mean-square error for the prediction of TAG chemistry to be 0.69 CH2 and 0.15 #C=C. When progressing to more complex samples such as oil emulsions and LDs in various eukaryotic cells, we find good agreement with bulk gas chromatography measurements. For differentiated adipocytes, we find a significant increase in the number of double bonds in small LDs (below 2 mu m in diameter) compared to large LDs (above 2 mu m in diameter). Coupled with a relatively limited sample preparation requirement, this approach should enable rapid and accurate TAG LD analysis for a variety of cell biology and technological applications.
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| 17. |
- Paul, Alexandra, 1988, et al.
(författare)
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Quantitative Mapping of Triacylglycerol Chain Length and Saturation Using Broadband CARS Microscopy
- 2019
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 116:12, s. 2346-2355
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Tidskriftsartikel (refereegranskat)abstract
- Lipid droplets (LDs), present in many cell types, are highly dynamic organelles that store neutral lipids, primarily triacylglycerols (TAGs). With the discovery of new LD functions (e.g., in immune response, protein clearage, and occurrence with disease), new methods to study LD chemical composition in situ are necessary. We present an approach for in situ, quantitative TAG analysis using label-free, coherent Raman microscopy that allows deciphering LD TAG composition in different biochemically complex samples with submicrometer spatial resolution. Employing a set of standard TAGs, we generate a spectral training matrix capturing the variation caused in Raman-like spectra by TAG backbone, chain length, and number of double bonds per chain, as well as the presence of proteins or other diluting molecules. Comparing our fitting approach to gas chromatography measurements for mixtures of standard TAGs and food oils, we find the root mean-square error for the prediction of TAG chemistry to be 0.69 CH2 and 0.15 #C=C. When progressing to more complex samples such as oil emulsions and LDs in various eukaryotic cells, we find good agreement with bulk gas chromatography measurements. For differentiated adipocytes, we find a significant increase in the number of double bonds in small LDs (below 2 μm in diameter) compared to large LDs (above 2 μm in diameter). Coupled with a relatively limited sample preparation requirement, this approach should enable rapid and accurate TAG LD analysis for a variety of cell biology and technological applications.
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| 18. |
- Rajan, M. R., et al.
(författare)
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Inhibition of FOXO1 transcription factor in primary human adipocytes mimics the insulin-resistant state of type 2 diabetes
- 2018
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Ingår i: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 475:10, s. 1807-1820
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Tidskriftsartikel (refereegranskat)abstract
- Type 2 diabetes is characterized by insulin resistance in the expanding adipose tissue of obesity. The insulin resistance manifests in human adipocytes as system-wide impairment of insulin signalling. An exception is the regulation of transcription factor FOXO1 (forkhead box protein O1), which is phosphorylated downstream of mTORC2 (mammalian/mechanistic target of rapamycin in complex with raptor) and is therefore not exhibiting impaired response to insulin. However, the abundance, and activity, of FOXO1 is reduced by half in adipocytes from patients with diabetes. To elucidate the effect of reduced FOXO1 activity, we here transduced human adipocytes with a dominant-negative construct of FOXO1 (DN-FOXO1). Inhibition of FOXO1 reduced the abundance of insulin receptor, glucose transporter-4, ribosomal protein S6, mTOR and raptor. Functionally, inhibition of FOXO1 induced an insulin-resistant state network-wide, a state that qualitatively and quantitatively mimicked adipocytes from patients with type 2 diabetes. In contrast, and in accordance with these effects of DN-FOXO1, overexpression of wild-type FOXO1 appeared to augment insulin signalling. We combined experimental data with mathematical modelling to show that the impaired insulin signalling in FOXO1-inhibited cells to a large extent can be explained by reduced mTORC1 activity - a mechanism that defines much of the diabetic state in human adipocytes. Our findings demonstrate that FOXO1 is critical for maintaining normal insulin signalling of human adipocytes.
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| 19. |
- Stanne, Tara M, 1979, et al.
(författare)
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Association of Plasma Brain-Derived Tau With Functional Outcome After Ischemic Stroke.
- 2024
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Ingår i: Neurology. - 1526-632X. ; 102:4
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Tidskriftsartikel (refereegranskat)abstract
- To investigate whether circulating acute-phase brain-derived tau (BD-tau) is associated with functional outcome after ischemic stroke.Plasma tau was measured by a novel assay that selectively quantifies BD-tau in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which includes adult cases with ischemic stroke and controls younger than 70 years, and in an independent cohort of adult cases of all ages (SAHLSIS2). Associations with unfavorable 3-month functional outcome (modified Rankin scale score >2) were analyzed by logistic regression. Various stratified and sensitivity analyses were performed, for example, by age, stroke severity, recanalization therapy, and etiologic subtype.This study included 454 and 364 cases from the SAHLSIS and SAHLSIS2, with a median age of 58 and 68 years, respectively. Higher acute BD-tau concentrations were significantly associated with increased odds of unfavorable outcome after adjustment for age, sex, day of blood draw, and stroke severity (NIH stroke scale score) in both cohorts (OR per doubling of BD-tau: 2.9 [95% CI 2.2-3.7], P = 1 × 10-15 and 1.8 [1.5-2.2], P = 7 × 10-9, respectively). The association was consistent in the different stratified and sensitivity analyses.BD-tau is a promising blood-based biomarker of ischemic stroke outcomes, and future studies in larger cohorts are warranted.
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| 20. |
- Stanne, Tara M, 1979, et al.
(författare)
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Longitudinal Study Reveals Long-Term Proinflammatory Proteomic Signature After Ischemic Stroke Across Subtypes
- 2022
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Ingår i: Stroke. - : Ovid Technologies (Wolters Kluwer Health). - 0039-2499 .- 1524-4628. ; 53:9, s. 2847-2858
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Tidskriftsartikel (refereegranskat)abstract
- Background: Inflammation contributes both to the pathogenesis of stroke and the response to brain injury. We aimed to identify proteins reflecting the acute-phase response and proteins more likely to reflect proinflammatory processes present before stroke by broadly profiling inflammation-related plasma proteins in a longitudinal ischemic stroke study. Methods: Participants were from a Swedish ischemic stroke cohort (SAHLSIS [Sahlgrenska Academy Study on Ischemic Stroke], n=600 cases and n=600 controls). Plasma levels of 65 proteins including chemokines, interleukins, surface molecules, and immune receptors were measured once in controls and at 3x in cases: during the acute phase, after 3 months, and for a subgroup (n=223) at 7-year follow-up. Associations between proteins and ischemic stroke or subtype were investigated in multivariable binary regression models corrected for age, sex, vascular risk factors, and multiple testing. Results: In the acute phase, 48 proteins were significantly and independently associated with ischemic stroke (false discovery rate adjusted P<0.05). At 3-month follow-up, 51 proteins and at 7-year follow-up 50 proteins were associated with ischemic stroke. The majority of proteins were upregulated in cases compared with controls (n=34 at all time points) and the most upregulated were CXCL5 (CXC chemokine ligand 5) and OSM (oncostatin M). Generally, large artery and cardioembolic stroke had the highest protein levels. However, several interesting subtype-specific differences were also detected at each time point. Conclusions: We found inflammation-related proteins that were differentially regulated in ischemic stroke cases compared with controls only in the acute phase and others that remained elevated also at later time points. This latter group of proteins could reflect underlying pathophysiological processes of relevance. Future studies both in terms of disease risk and prognostication are warranted.
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| 21. |
- Usman Ali, Syed, et al.
(författare)
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Intracellular K+ Determination With a Potentiometric Microelectrode Based on ZnO Nanowires
- 2011
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Ingår i: IEEE Transactions on Nanotechnology. - : IEEE. - 1536-125X .- 1941-0085. ; 10:4, s. 913-919
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Tidskriftsartikel (refereegranskat)abstract
- The fabrication and application of an intracellular K+-selective microelectrode is demonstrated. ZnO nanowires with a diameter of 100-180 nm and a length of approximately 1.5. m are grown on a borosilicate glass microcapillary. The ZnO nanowires were coated by a K+-ionophore-containing membrane. The K+-selective microelectrode exhibited a K+-dependent potentiometric response versus an Ag/AgCl reference microelectrode that was linear over a large concentration range (25 . M-125 mM) with a minimum detection limit of 1 . M. The measured K+ concentrations in human adipocytes and in frog oocytes were consistent with values of K+ concentrations reported in the literature. The sensor has several advantages including ease of fabrication, ease of insertion into the cells, low cost, and high selectivity features that make this type of sensor suitable to characterize physiologically relevant ions within single living cells.
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| 22. |
- Öst, Anita, 1965-, et al.
(författare)
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Attenuated mTOR signaling and enhanced autophagy in adipocytes from obese patients with type 2 diabetes
- 2010
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Ingår i: Molecular Medicine. - : Feinstein Institute for Medical Research. - 1076-1551 .- 1528-3658. ; 16:07-Aug, s. 235-246
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Tidskriftsartikel (refereegranskat)abstract
- The protein kinase mammalian target of rapamycin (mTOR) mediates insulin control ofprotein synthesis, autophagy, mitochondrial function, and, through feedback signaling tophosphorylation of IRS1 at serine residues, mTOR directly controls insulin signaling. Weshow that in adipocytes from patients with type 2 diabetes (T2D) insulin activation of mTORis attenuated and that the resultant phenotype is compatible with, and can be mimicked by,loss of mTOR activation. In T2D adipocytes mitochondrial function is impaired andautophagy strongly upregulated, with concomitant increased autophagic destruction ofmitochondria and lipofuscin particles, and a dependence on autophagy for ATP production.Conversely, mitochondrial dysfunction attenuates insulin activation of mTOR, enhancesautophagy and attenuates feedback to IRS1. Our findings put mTOR in the driver´s seat of aninsulin resistance that in adipocytes can be fuelled by mitochondrial dysfunction,inflammation, ER-stress, or hypoxia.
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