Rattus norvegicus
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PROVIDER: PRJNA187510 | ENA |
REPOSITORIES: ENA
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Project description:Aims/hypothesis: While lipid deposition in skeletal muscle is considered to be involved in obesity-associated insulin resistance, neutral intramyocellular lipid (IMCL) accumulation per se does not necessarily induce insulin resistance. We previously demonstrated that overexpression of the lipid droplet coat protein perilipin 2 augments intramyocellular lipid content while improving insulin sensitivity. Another member of the perilipin family, perilipin 5 (PLIN5), is predominantly expressed in oxidative tissues like skeletal muscle. Here we investigated the effects of PLIN5 overexpression M-bM-^@M-^S in comparison with effects of PLIN2 M-bM-^@M-^S on skeletal muscle lipid levels, gene expression profiles and insulin sensitivity. Methods: Gene electroporation was used to overexpress PLIN5 in tibialis anterior muscle of rats fed a high fat diet. Eight days after electroporation, insulin-mediated glucose uptake in skeletal muscle was measured by means of a hyperinsulinemic euglycemic clamp. Electron microscopy, fluorescence microscopy and lipid extractions were performed to investigate IMCL accumulation. Gene expression profiles were obtained using microarrays. Results: TAG storage and lipid droplet size increased upon PLIN5 overexpression. Despite the higher IMCL content, insulin sensitivity was not impaired and DAG and acylcarnitine levels were unaffected. In contrast to the effects of PLIN2 overexpression, microarray data analysis revealed a gene expression profile favoring FA oxidation and improved mitochondrial function. Conclusions/interpretation: Both PLIN2 and PLIN5 increase neutral IMCL content without impeding insulin-mediated glucose uptake. As opposed to the effects of PLIN2 overexpression, overexpression of PLIN5 in skeletal muscle promoted expression of a cluster of genes under control of PPARM-NM-1 and PGC1M-NM-1 involved in FA catabolism and mitochondrial oxidation. Rats received a high fat diet for 3 weeks; 2 weeks after start of the diet intervention Plin5 (OXPAT) or Plin2 (ADRP) were overexpressed in either the right or left tibialis anterior muscle. One week later pooled tibialis anterior muscle samples were analysed on microarrays.
2013-01-29 | E-GEOD-43832 | biostudies-arrayexpress
Project description:Aims/hypothesis: While lipid deposition in skeletal muscle is considered to be involved in obesity-associated insulin resistance, neutral intramyocellular lipid (IMCL) accumulation per se does not necessarily induce insulin resistance. We previously demonstrated that overexpression of the lipid droplet coat protein perilipin 2 augments intramyocellular lipid content while improving insulin sensitivity. Another member of the perilipin family, perilipin 5 (PLIN5), is predominantly expressed in oxidative tissues like skeletal muscle. Here we investigated the effects of PLIN5 overexpression – in comparison with effects of PLIN2 – on skeletal muscle lipid levels, gene expression profiles and insulin sensitivity. Methods: Gene electroporation was used to overexpress PLIN5 in tibialis anterior muscle of rats fed a high fat diet. Eight days after electroporation, insulin-mediated glucose uptake in skeletal muscle was measured by means of a hyperinsulinemic euglycemic clamp. Electron microscopy, fluorescence microscopy and lipid extractions were performed to investigate IMCL accumulation. Gene expression profiles were obtained using microarrays. Results: TAG storage and lipid droplet size increased upon PLIN5 overexpression. Despite the higher IMCL content, insulin sensitivity was not impaired and DAG and acylcarnitine levels were unaffected. In contrast to the effects of PLIN2 overexpression, microarray data analysis revealed a gene expression profile favoring FA oxidation and improved mitochondrial function. Conclusions/interpretation: Both PLIN2 and PLIN5 increase neutral IMCL content without impeding insulin-mediated glucose uptake. As opposed to the effects of PLIN2 overexpression, overexpression of PLIN5 in skeletal muscle promoted expression of a cluster of genes under control of PPARα and PGC1α involved in FA catabolism and mitochondrial oxidation.
2013-01-29 | GSE43832 | GEO
Project description:Type 2 diabetes is characterized by excessive lipid storage in skeletal muscle. Excessive intramyocellular lipid storage exceeds intracellular needs and induces lipotoxic events ultimately contributing to the development of insulin resistance. Lipid droplet (LD)-coating proteins may control proper lipid storage in skeletal muscle. Perilipin 2 (PLIN2/ADRP) is one of the most abundantly expressed LD-coating proteins in skeletal muscle. Here we examined the role of PLIN2 in myocellular lipid handling and insulin sensitivity by investigating the effects of in vitro PLIN2 knockdown and in vitro and in vivo overexpression. PLIN2 knockdown decreased LD formation and triacylglycerol storage, marginally increased FA oxidation, and increased incorporation of palmitate into diacylglycerols and phospholipids. PLIN2 overexpression in vitro increased intramyocellular TAG storage paralleled with improved insulin sensitivity. In vivo muscle-specific PLIN2 overexpression resulted in increased LD accumulation and blunted the high-fat diet-induced increase of OXPHOS protein content. Diacylglycerol levels were unchanged, while ceramide levels were increased. Despite the increased intramyocellular lipid accumulation, PLIN2 overexpression improved skeletal muscle insulin sensitivity. We conclude that PLIN2 is essential for lipid storage in skeletal muscle by enhancing the partitioning of excess FAs towards triacylglycerol storage in LDs thereby blunting lipotoxicity-associated insulin resistance. C2C12 cells (mouse myoblast cell line) were treated with fatty acids and effects of knockdown of Perilipin 2 by siRNA were studied by gene expression profiling.
2012-06-08 | E-GEOD-38590 | biostudies-arrayexpress
Project description:Type 2 diabetes is characterized by excessive lipid storage in skeletal muscle. Excessive intramyocellular lipid storage exceeds intracellular needs and induces lipotoxic events ultimately contributing to the development of insulin resistance. Lipid droplet (LD)-coating proteins may control proper lipid storage in skeletal muscle. Perilipin 2 (PLIN2/ADRP) is one of the most abundantly expressed LD-coating proteins in skeletal muscle. Here we examined the role of PLIN2 in myocellular lipid handling and insulin sensitivity by investigating the effects of in vitro PLIN2 knockdown and in vitro and in vivo overexpression. PLIN2 knockdown decreased LD formation and triacylglycerol storage, marginally increased FA oxidation, and increased incorporation of palmitate into diacylglycerols and phospholipids. PLIN2 overexpression in vitro increased intramyocellular TAG storage paralleled with improved insulin sensitivity. In vivo muscle-specific PLIN2 overexpression resulted in increased LD accumulation and blunted the high-fat diet-induced increase of OXPHOS protein content. Diacylglycerol levels were unchanged, while ceramide levels were increased. Despite the increased intramyocellular lipid accumulation, PLIN2 overexpression improved skeletal muscle insulin sensitivity. We conclude that PLIN2 is essential for lipid storage in skeletal muscle by enhancing the partitioning of excess FAs towards triacylglycerol storage in LDs thereby blunting lipotoxicity-associated insulin resistance.
2012-06-09 | GSE38590 | GEO
Project description:OBJECTIVE Diet intervention in obese adults is the first strategy to induce weight loss and to improve insulin sensitivity. We hypothesized that improvements in insulin sensitivity after weight loss from a short-term dietary intervention tracks with alterations in expression of metabolic genes and abundance of specific lipid species. RESEARCH DESIGN AND METHODS Eight obese, insulin resistant, non-diabetic adults were recruited to participate in a three-week low calorie diet intervention study (1000 kcal/day). Fasting blood samples and vastus lateralis skeletal muscle biopsies were obtained before and after the dietary intervention. Clinical chemistry and measures of insulin sensitivity were determined. Unbiased microarray gene expression and targeted lipidomic analysis of skeletal muscle was performed. RESULTS Body weight was reduced, insulin sensitivity (HOMA-IR) was enhanced, and serum insulin concentration and blood lipid (triglyceride, cholesterol, LDL and HDL) levels were improved after dietary intervention. Gene set enrichment analysis of skeletal muscle revealed that oxidative phosphorylation and inflammatory processes were among the most enriched KEGG-pathways identified after dietary intervention. mRNA expression of PDK4 and MLYCD increased, while SCD decreased in skeletal muscle after dietary intervention. Dietary intervention altered the intramuscular lipid profile of skeletal muscle, with changes in content of phosphatidylcholine and triglyceride species among the pronounced. CONCLUSIONS Short-term diet intervention and weight loss in obese adults alters metabolic gene expression and reduces specific phosphatidylcholine and triglyceride species in skeletal muscle, concomitant with improvements in clinical outcomes and enhanced insulin sensitivity.
2019-02-05 | GSE103682 | GEO
Project description:The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.
2019-08-14 | GSE134957 | GEO
Project description:The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.
2019-08-14 | GSE134956 | GEO
Project description:The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.
2019-08-14 | GSE134913 | GEO
Project description:The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.
2019-08-14 | GSE135063 | GEO
Project description:Dietary fat quality may influence skeletal muscle lipid handling and fat accumulation, thereby modulating insulin sensitivity. Objective: To examine acute effects of meals with various fatty acid (FA) compositions on skeletal muscle FA handling and postprandial insulin sensitivity in obese insulin resistant men. Design: In a single-blinded randomized crossover study, 10 insulin resistant men consumed three high-fat mixed-meals (2.6MJ). Meals were high in saturated FA (SFA), in monounsaturated FA (MUFA) or in polyunsaturated FA (PUFA). Fasting and postprandial skeletal muscle FA handling were examined by measuring arterio-venous concentration differences across forearm muscle. [2H2]-palmitate was infused intravenously to label endogenous triacylglycerol (TAG) and FFA in the circulation and [U-13C]-palmitate was added to the meal to label chylomicron-TAG. Skeletal muscle biopsies were taken to assess intramuscular lipid metabolism and gene expression. Results: Insulin and glucose responses (AUC) after SFA meal were significantly higher compared with PUFA meal (p=0.003 and 0.028, respectively). Uptake of TAG-derived FA was significantly lower in the early postprandial phase after PUFA meal as compared with other meals (AUC60-120, p<0.001). The PUFA meal induced less transcriptional downregulation of oxidative pathways compared with other meals. The fractional synthetic rate was higher in DAG and PL fraction after MUFA and PUFA meal. Conclusion: Intake of a PUFA meal reduced TAG-derived skeletal muscle FA uptake, which was accompanied by higher postprandial insulin sensitivity and a tendency towards a higher muscle lipid turnover. These data suggest that the effects of replacement of SFA by PUFA may contribute to less muscle lipid uptake and may be therefore protective against the development of insulin resistance. Keywords: expression profiling by array randomized crossover dietary intervention study
2012-02-21 | E-GEOD-31901 | biostudies-arrayexpress