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Altered intestinal functions and increased local inflammation in insulin-resistant obese subjects: a gene-expression profile analysis.

ABSTRACT: Metabolic alterations relevant to postprandial dyslipidemia were previously identified in the intestine of obese subjects with systemic insulin resistance. These dysregulations were closely associated with an amplification of intestinal lipogenesis and lipoprotein output, which was triggered by insulin resistance likely sustained by oxidative stress and inflammation. The aim of the study was to identify the genes deregulated by the presence of systemic insulin resistance in the intestine of severely obese subjects. Transcripts from duodenal samples of insulin-sensitive (HOMA-IR<3, n=9) and insulin-resistant (HOMA-IR>7, n=9) obese subjects were assayed by microarray (Illumina HumanHT-12). The small intestine exhibits a highly specific mRNA expression profile that was similar between insulin-sensitive and insulin-resistant individuals. A total of 195 annotated genes were identified as differentially expressed between these two groups with a fold change higher than 1.2. Metabolic pathway analysis revealed that 36 differently expressed genes were directly involved in known intestinal functions, including digestion, extracellular matrix, endocrine system, immunity, inflammation/oxidative stress and cholesterol metabolism. Several signaling pathways involved in immunity and inflammation were significantly enriched in differently expressed genes and were predicted to be activated in the intestine of insulin-resistant subjects. Using stringent criteria (Fold change>1.5; FDR<0.05), only three genes were found to be significantly and differently expressed in the intestine of insulin-resistant compared to insulin-sensitive subjects: the transcripts of the insulinotropic glucose-dependant peptide (GIP) and of the β-microseminoprotein (MSMB) were significantly reduced, but that of the humanin like-1 (HNL1) protein was significantly increased. These results underline that systemic insulin resistance is associated with an amplification of local inflammatory process and remodeling of key intestinal functions. Genes identified in this study are potentially triggered throughout the development of intestinal metabolic alterations, which could contribute to dyslipidemia, a component of metabolic syndrome and diabetes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE63992 | GEO | 2017/11/30

SECONDARY ACCESSION(S): PRJNA269734

REPOSITORIES: GEO

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Project description:Purpose. Insulin resistant muscle is resistant to gene expression changes induced by acute exercise. This study was undertaken to identify transcription factors that differentially respond to exercise in insulin resistance. Candidate transcription factors were identified from analysis of 5’-untranslated regions (5’-UTRs) of exercise responsive genes and from analysis of the 5’-UTRs of genes coding for proteins that differ in abundance in insulin resistance. Research design and methods. Muscle biopsies were obtained from lean and obese subjects before and after a single exercise bout. Euglycemic glucose clamps assessed insulin sensitivity. Global proteomics analysis identified differentially abundant proteins. The 5’-UTRs of genes coding for significant proteins were subjected to transcription factor enrichment analysis to identify candidate transcription factors. Q-rt-PCR to determine expression of candidate transcription factors was performed on RNA from resting and post-exercise muscle biopsies; immunoblots quantified protein abundance. Results. Obese subjects were insulin resistant compared to lean but performed exercise at the same intensity. Proteins involved in mitochondrial function, protein targeting and translation, and metabolism were among those significantly different between the groups. Transcription factor enrichment analysis of genes coding for these proteins revealed new candidate transcription factors. Q-rt-PCR analysis of RNA and immunoblot analysis from pre- and post-exercise muscle biopsies revealed several transcription and growth factors that had altered responses to exercise in insulin resistant subjects. Conclusions. These results confirm findings of an association between insulin sensitivity and transcription factor mRNA response to exercise and extend these results to show that obesity also may be a sufficient prerequisite for exercise resistance. Analysis of the muscle proteome together with determination of effects of exercise on expression of transcription factors suggests that abnormal responses of transcription factors to exercise may be responsible for differences in protein abundances in insulin resistant muscle.

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Altered intestinal functions and increased local inflammation in insulin-resistant obese subjects: a gene-expression profile analysis.

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