Glucocorticoid receptor ChIP-sequencing of subcutaneous fat reveals modulation of inflammatory pathways

Abstract

Objective: To identify glucocorticoid receptor (GR)-associated chromatin sequences and target genes in primary human abdominal subcutaneous fat.

Methods: GR chromatin immunoprecipitation (ChIP)-sequencing (seq) methodology in subcutaneous human adipocytes treated ex vivo with dexamethasone (dex) was optimized to identify genome-wide dex-dependent GR-binding regions (GBRs). Gene expression analyses were performed in parallel ± dex treatment.

Results: Fat was obtained from four female surgical patients without obesity with a median age of 50.5 years. ChIP-seq analysis revealed 219 dex-associated GBRs. Of these, 136 GBRs were located within 100 kb of the transcriptional start site and associated with 123 genes. Combining these data with dex-induced gene expression, 70 of the 123 putative direct target genes were significantly up- or downregulated following 4 hours of dex treatment. Gene expression analysis demonstrated that the top 10 pathways reflected regulation of cellular metabolism and inflammation. DEPTOR, an inhibitor of mTOR, was identified as a potential direct GR target gene.

Conclusions: This is the first report of genome-wide GR ChIP-seq and gene expression analysis in human fat. The results implicate regulation of key GR target genes that are involved in dampening inflammation and promoting cellular metabolism.