Berberine Alleviates Hepatic Steatosis by Restoring CPT1α Histone Acetylation and Modulating HDAC2/SIRT2.

Abstract

Background: High-fat diet (HFD)-driven hepatic steatosis is associated with impaired mitochondrial fatty acid oxidation and dysregulated expression of genes that control lipid disposal. Carnitine palmitoyltransferase 1α (CPT1α), encoded by Cpt1a, is the rate-limiting enzyme for mitochondrial fatty acid β-oxidation and responds to nutritional stress. However, the chromatin mechanisms that regulate Cpt1a in diet-induced steatosis remain incompletely defined.

Objectives: To map histone modifications at the hepatic Cpt1a locus and determine whether berberine (BBR) is associated with the restoration of Cpt1a transcription through histone acetylation remodeling.

Methods: Male Sprague-Dawley rats were assigned to the normal diet (ND), high-fat diet (HFD), or berberine (BBR)+HFD group (n = 8 initially), with individual rats as the experimental unit. ChIP-qPCR was performed on archived liver samples (ND, n = 6; HFD, n = 8; BBR+HFD, n = 8) and normalized to input DNA. In BRL cells, TSA (100 nM) and SAHA (20 μM) were used to assess HDAC-sensitive regulation of Cpt1a.

Results: HFD reduced H3/H4 acetylation and increased H3K9 methylation at Cpt1a regulatory regions. BBR restored H3/H4 acetylation, selectively reduced H3K9me3 at +12 kb, and attenuated HFD-induced increases in HDAC2 and SIRT2 mRNA (approximately 40-fold and 3.8-fold, respectively) toward baseline. TSA and SAHA increased Cpt1a mRNA at 24 h by approximately 8.1-fold and 5.4-fold, respectively. Palmitate reduced Cpt1a expression by approximately 58%, and this repression was reversed by BBR or TSA.

Conclusions: BBR alleviates HFD-induced hepatic steatosis, concomitant with the restoration of Cpt1a histone acetylation and modulation of HDAC2/SIRT2. These data support, but do not prove, an HDAC2/SIRT2-linked chromatin mechanism and should be interpreted as a candidate pathway requiring further functional validation.