Piperine inhibits adipocyte differentiation via dynamic regulation of histone modifications

Previously, we reported that piperine, one of the major pungent components in black pepper, attenuates adipogenesis by repressing PPARγ activity in 3T3-L1 preadipocytes. However, the epigenetic mechanisms underlying this activity remain unexplored. Here, gene set enrichment analysis using microarray data indicated that there was significant downregulation of adipogenesis-associated and PPARγ target genes and upregulation of genes bound with H3K27me3 in response to piperine. As shown by Gene Ontology analysis, the upregulated genes are related to lipid oxidation and polycomb repressive complex 2 (PRC2). Chromatin immunoprecipitation assays revealed that PPARγ (and its coactivators), H3K4me3, and H3K9ac were less enriched at the PPAR response element of three adipogenic genes, whereas increased accumulation of H3K9me2, H3K27me3, and Ezh2 was found, which likely led to the reduced gene expression. Further analysis using three lipolytic genes revealed the opposite enrichment pattern of H3K4me3 and H3K27me3 at the Ezh2 binding site. Treatment with GSK343, an Ezh2 inhibitor, elevated lipolytic gene expression by decreasing the enrichment of H3K27me3 during adipogenesis, which confirms that Ezh2 plays a repressive role in lipolysis. Overall, these results suggest that piperine regulates the expression of adipogenic and lipolytic genes by dynamic regulation of histone modifications, leading to the repression of adipocyte differentiation.