Genomewide approaches for BACH1 target genes in mouse embryonic fibroblasts showed BACH1-Pparg pathway in adipogenesis

The transcription repressor BTB and CNC homology 1 (BACH1) represses genes involved in heme metabolism and oxidative stress response. BACH1 also suppresses the p53-dependent cellar senescence in primary mouse embryonic fibroblasts (MEFs). To investigate the role of BACH1 in MEF other than its known functions, we carried out a genomewide mapping of binding site for BACH1 and its heterodimer partner MAFK in immortalized MEFs (iMEFs) using chromatin immunoprecipitation and next-generation sequencing technology (ChIP-sequence). The comparative analysis of the ChIP-sequence data and DNA microarray data from Bach1-deficient and wild-type (WT) iMEF showed 35 novel candidate target genes of BACH1. Among these genes, five genes (Pparg, Nfia, Ptplad2, Adcy1 and Ror1) were related with lipid metabolism. Bach1-deficient iMEFs showed increased expression of mRNA and protein of PPAR gamma, which is the key factor of adipogenesis. These cells also showed a concomitant increase in ligand-dependent activation of PPAR gamma target genes compared with wild-type iMEFs. Moreover, Bach1-deficient iMEFs efficiently differentiated to adipocyte compared with wild-type cells in the presence of PPAR gamma ligands. Our results suggest that BACH1 regulates expression of adipocyte-related genes including Pparg and potentiates adipocyte differentiation capacity.