Rapid Communication: The correlation between histone modifications and expression of key genes involved in accumulation of adipose tissue in the pig

Histone modification is a well-known epigenetic mechanism involved in regulation of gene expression; however, it has been poorly studied in adipose tissues of the pig. Understanding the molecular background of adipose tissue development and function is essential for improving production efficiency and meat quality. The objective of this study was to identify the association between histone modification and the transcript level of genes important for lipid droplet formation and metabolism. Histone modifications at the promoter regions of 6 genes (SNAP23, BSCL2, COPA, LEP, SCD, and FABP4) were analyzed using a chromatin immunoprecipitation assay. Two modifications involved in activation of gene expression (acetylation of H3 histone at lysine 9 and methylation of H3 histone at lysine 4) as well as methylation of H3 histone at lysine 27, which is known to be related to gene repression, were examined. The level of histone modification was compared with transcript abundance determined using real-time PCR in tissue samples (subcutaneous fat, visceral fat, and longissimus dorsi muscle) derived from 3 pig breeds significantly differing in fatness traits (Polish Large White, Duroc, and Pietrain). Transcript levels were found to be correlated with histone modifications characteristic to active loci in 4 of 6 genes. A positive correlation between histone H3 lysine 9 acetylation modification and the transcript level of SNAP23 (r = 0.53, P < 4.8 x 10(-3)), BSCL2 (r = 0.34, P < 0.02), and LEP (r = 0.43, P < 1.0 x 10(-5)) genes was observed. The histone H3 lysine 4 trimethylation modification correlated with transcripts of SNAP23 (r = 0.64, P < 4.6 x 10(-4)) and COPA (r = 0.37, P < 0.01) genes. No correlation was found between transcript level of all studied genes and histone H3 lysine 27 trimethylation level. This is the first study on histone modifications in porcine adipose tissues. We confirmed the relationship between histone modifications and expression of key genes for adipose tissue accumulation in the pig. Epigenetic modulation of the transcriptional profile of these genes (e.g., through nutritional factors) may improve porcine fatness traits in future.