An intronic enhancer of Cebpa regulates adipocyte differentiation and adipose tissue development via long‐range loop formation

Abstract

AbstractCebpa is a master transcription factor gene for adipogenesis. However, the mechanisms of enhancer–promoter chromatin interactions controlling Cebpa transcriptional regulation during adipogenic differentiation remain largely unknown. To reveal how the three‐dimensional structure of Cebpa changes during adipogenesis, we generated high‐resolution chromatin interactions of Cebpa in 3T3‐L1 preadipocytes and 3T3‐L1 adipocytes using circularized chromosome conformation capture sequencing (4C‐seq). We revealed dramatic changes in chromatin interactions and chromatin status at interaction sites during adipogenic differentiation. Based on this, we identified five active enhancers of Cebpa in 3T3‐L1 adipocytes through epigenomic data and luciferase reporter assays. Next, epigenetic repression of Cebpa‐L1‐AD‐En2 or ‐En3 by the dCas9‐KRAB system significantly down‐regulated Cebpa expression and inhibited adipocyte differentiation. Furthermore, experimental depletion of cohesin decreased the interaction intensity between Cebpa‐L1‐AD‐En2 and the Cebpa promoter and down‐regulated Cebpa expression, indicating that long‐range chromatin loop formation was mediated by cohesin. Two transcription factors, RXRA and PPARG, synergistically regulate the activity of Cebpa‐L1‐AD‐En2. To test whether Cebpa‐L1‐AD‐En2 plays a role in adipose tissue development, we injected dCas9‐KRAB‐En2 lentivirus into the inguinal white adipose tissue (iWAT) of mice to suppress the activity of Cebpa‐L1‐AD‐En2. Repression of Cebpa‐L1‐AD‐En2 significantly decreased Cebpa expression and adipocyte size, altered iWAT transcriptome, and affected iWAT development. We identified functional enhancers regulating Cebpa expression and clarified the crucial roles of Cebpa‐L1‐AD‐En2 and Cebpa promoter interaction in adipocyte differentiation and adipose tissue development.