Dataset Information

Endurance Runners with Intramyocellular Lipid Accumulation and High Insulin Sensitivity Have Enhanced Expression of Genes Related to Lipid Metabolism in Muscle.

ABSTRACT:

Context

Endurance-trained athletes have high oxidative capacities, enhanced insulin sensitivities, and high intracellular lipid accumulation in muscle. These characteristics are likely due to altered gene expression levels in muscle.

Design and setting

We compared intramyocellular lipid (IMCL), insulin sensitivity, and gene expression levels of the muscle in eight nonobese healthy men (control group) and seven male endurance athletes (athlete group). Their IMCL levels were measured by proton-magnetic resonance spectroscopy, and their insulin sensitivity was evaluated by glucose infusion rate (GIR) during a euglycemic-hyperinsulinemic clamp. Gene expression levels in the vastus lateralis were evaluated by quantitative RT-PCR (qRT-PCR) and microarray analysis.

Results

IMCL levels in the tibialis anterior muscle were approximately 2.5 times higher in the athlete group compared to the control group, while the IMCL levels in the soleus muscle and GIR were comparable. In the microarray hierarchical clustering analysis, gene expression patterns were not clearly divided into control and athlete groups. In a gene set enrichment analysis with Gene Ontology gene sets, "RESPONSE TO LIPID" was significantly upregulated in the athlete group compared with the control group. Indeed, qRT-PCR analysis revealed that, compared to the control group, the athlete group had 2-3 times higher expressions of proliferator-activated receptor gamma coactivator-1 alpha (PGC1A), adiponectin receptors (AdipoRs), and fatty acid transporters including fatty acid transporter-1, plasma membrane-associated fatty acid binding protein, and lipoprotein lipase.

Conclusions

Endurance runners with higher IMCL levels have higher expression levels of genes related to lipid metabolism such as PGC1A, AdipoRs, and fatty acid transporters in muscle.

SUBMITTER: Kakehi S

PROVIDER: S-EPMC7762159 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Publications

Endurance Runners with Intramyocellular Lipid Accumulation and High Insulin Sensitivity Have Enhanced Expression of Genes Related to Lipid Metabolism in Muscle.

Kakehi Saori S Tamura Yoshifumi Y Takeno Kageumi K Ikeda Shin-Ichi SI Ogura Yuji Y Saga Norio N Miyatsuka Takeshi T Naito Hisashi H Kawamori Ryuzo R Watada Hirotaka H

Journal of clinical medicine 20201206 12

<h4>Context</h4>Endurance-trained athletes have high oxidative capacities, enhanced insulin sensitivities, and high intracellular lipid accumulation in muscle. These characteristics are likely due to altered gene expression levels in muscle.<h4>Design and setting</h4>We compared intramyocellular lipid (IMCL), insulin sensitivity, and gene expression levels of the muscle in eight nonobese healthy men (control group) and seven male endurance athletes (athlete group). Their IMCL levels were measure ...[more]

PMID: 33291227

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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.

Project description:BACKGROUND/OBJECTIVES:Accumulation of lipid droplets inside skeletal muscle fibers (intramyocellular lipids or IMCL) with increasing obesity has been linked to skeletal muscle insulin resistance and risk of type 2 diabetes in both adults and prepubertal children. We aimed to evaluate the associations of race, genotype, prenatal factors, and postnatal factors with IMCL in early childhood. SUBJECTS/METHODS:This study was a secondary analysis performed on the GUSTO birth cohort. Soleus muscle IMCL of 392 children at 4.5 years of age was measured by magnetic resonance spectroscopy, of which usable imaging data were obtained from 277 children (137 Chinese, 87 Malays, and 53 Indians). Metabolic assessments (fasting glucose, insulin, and HOMA-IR) were performed at age 6. RESULTS:The mean IMCL level at 4.5 years was 0.481?±?0.279% of water resonance (mean?±?sd). Corroborating with results from adults, Indian children had the highest IMCL levels compared with Malay and Chinese children. Among the prenatal factors, the rate of gestational weight gain (GWG rate) was associated with offspring IMCL (B?=?0.396 (0.069, 0.724); p?=?0.018). Both race and GWG rate continued to be associated with offspring IMCL even after accounting for current offspring BMI. Postnatally, IMCL was associated with shorter breastfeeding duration (B?=?0.065 (0.001, 0.128); p?=?0.045) and conditional relative weight gain between ages 2 and 3 (B?=?0.052 (0.012, 0.093); p?=?0.012). The associations with postnatal factors were attenuated after adjusting for current offspring BMI. IMCL was positively associated with offspring BMI (B?=?0.028 (0.012, 0.044); p?=?0.001). IMCL levels were not associated with fasting glucose, fasting insulin, and HOMA-IR at age 6. CONCLUSION:This study provides evidence that IMCL accumulation occurs in early childhood and that developmental factors and race are associated with it. We also show that early childhood IMCL accumulation is well tolerated, suggesting that the adverse associations between IMCL and insulin resistance may emerge at older ages.

Project description:ImportanceExcess body weight and insulin resistance lead to type 2 diabetes and other major health problems. There is an urgent need for dietary interventions to address these conditions.ObjectiveTo measure the effects of a low-fat vegan diet on body weight, insulin resistance, postprandial metabolism, and intramyocellular and hepatocellular lipid levels in overweight adults.Design, setting, and participantsThis 16-week randomized clinical trial was conducted between January 2017 and February 2019 in Washington, DC. Of 3115 people who responded to flyers in medical offices and newspaper and radio advertisements, 244 met the participation criteria (age 25 to 75 years; body mass index of 28 to 40) after having been screened by telephone.InterventionsParticipants were randomized in a 1:1 ratio. The intervention group (n = 122) was asked to follow a low-fat vegan diet and the control group (n = 122) to make no diet changes for 16 weeks.Main outcomes and measuresAt weeks 0 and 16, body weight was assessed using a calibrated scale. Body composition and visceral fat were measured by dual x-ray absorptiometry. Insulin resistance was assessed with the homeostasis model assessment index and the predicted insulin sensitivity index (PREDIM). Thermic effect of food was measured by indirect calorimetry over 3 hours after a standard liquid breakfast (720 kcal). In a subset of participants (n = 44), hepatocellular and intramyocellular lipids were quantified by proton magnetic resonance spectroscopy. Repeated measure analysis of variance was used for statistical analysis.ResultsAmong the 244 participants in the study, 211 (87%) were female, 117 (48%) were White, and the mean (SD) age was 54.4 (11.6) years. Over the 16 weeks, body weight decreased in the intervention group by 5.9 kg (95% CI, 5.0-6.7 kg; P < .001). Thermic effect of food increased in the intervention group by 14.1% (95% CI, 6.5-20.4; P < .001). The homeostasis model assessment index decreased (-1.3; 95% CI, -2.2 to -0.3; P < .001) and PREDIM increased (0.9; 95% CI, 0.5-1.2; P < .001) in the intervention group. Hepatocellular lipid levels decreased in the intervention group by 34.4%, from a mean (SD) of 3.2% (2.9%) to 2.4% (2.2%) (P = .002), and intramyocellular lipid levels decreased by 10.4%, from a mean (SD) of 1.6 (1.1) to 1.5 (1.0) (P = .03). None of these variables changed significantly in the control group over the 16 weeks. The change in PREDIM correlated negatively with the change in body weight (r = -0.43; P < .001). Changes in hepatocellular and intramyocellular lipid levels correlated with changes in insulin resistance (both r = 0.51; P = .01).Conclusions and relevanceA low-fat plant-based dietary intervention reduces body weight by reducing energy intake and increasing postprandial metabolism. The changes are associated with reductions in hepatocellular and intramyocellular fat and increased insulin sensitivity.Trial registrationClinicalTrials.gov Identifier: NCT02939638.

Dataset Information

Endurance Runners with Intramyocellular Lipid Accumulation and High Insulin Sensitivity Have Enhanced Expression of Genes Related to Lipid Metabolism in Muscle.

Context

Design and setting

Results

Conclusions

Publications

Endurance Runners with Intramyocellular Lipid Accumulation and High Insulin Sensitivity Have Enhanced Expression of Genes Related to Lipid Metabolism in Muscle.

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