Baik M, Vu T T T, Piao M Y, Kang H J
Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea ; Institute of Green Bio Science Technology, Pyeungchang 232-916, Korea .
Department of Molecular Biotechnology, Chonnam National University, Gwangju 500-757, Korea .
Asian-Australas J Anim Sci. 2014 Oct;27(10):1493-8. doi: 10.5713/ajas.2014.14283.
Epigenetic factors, such as DNA methylation status, may regulate adipogenesis and lipogenesis, thus affecting intramuscular fat (IMF) deposition in longissimus dorsi muscle (LM) of beef cattle. In Korean cattle steers, the LM consists mainly of muscle tissue. However, the LM tissue also contains IMF. We compared the gene expression levels between the IMF and muscle portions of the LM after tissue separation. Real-time polymerase chain reaction analysis showed that the mRNA levels of both adipogenic peroxisome proliferator-activated receptor gamma isoform 1 (PPARG1) and lipogenic fatty acid binding protein 4 (FABP4) were higher (p<0.01) in the IMF than in the muscle portion of the LM. We determined DNA methylation levels of regulatory regions of the PPARG1 and FABP4 genes by pyrosequencing of genomic DNA. DNA methylation levels of two of three CpG sites in the PPARG1 gene promoter region were lower (p<0.05) in the IMF than in the muscle portion of the LM. DNA methylation levels of all five CpG sites from the FABP4 gene promoter region were also lower (p<0.001) in the IMF than in the muscle portion. Thus, mRNA levels of both PPARG1 and FABP4 genes were inversely correlated with DNA methylation levels in regulatory regions of CpG sites of the corresponding gene. Our findings suggest that DNA methylation status regulates tissue-specific expression of adipogenic and lipogenic genes in the IMF and muscle portions of LM tissue in Korean cattle.
表观遗传因素，如DNA甲基化状态，可能调节脂肪生成和脂质生成，从而影响肉牛背最长肌（LM）中肌内脂肪（IMF）的沉积。在韩牛阉牛中，LM主要由肌肉组织组成。然而，LM组织中也含有IMF。我们在组织分离后比较了LM的IMF和肌肉部分之间的基因表达水平。实时聚合酶链反应分析表明，成脂过氧化物酶体增殖物激活受体γ亚型1（PPARG1）和生脂脂肪酸结合蛋白4（FABP4）的mRNA水平在IMF中均高于（p<0.01）LM的肌肉部分。我们通过对基因组DNA进行焦磷酸测序来确定PPARG1和FABP4基因调控区域的DNA甲基化水平。PPARG1基因启动子区域三个CpG位点中的两个位点的DNA甲基化水平在IMF中低于（p<0.05）LM的肌肉部分。FABP4基因启动子区域所有五个CpG位点的DNA甲基化水平在IMF中也低于（p<0.001）肌肉部分。因此，PPARG1和FABP4基因的mRNA水平与相应基因CpG位点调控区域的DNA甲基化水平呈负相关。我们的研究结果表明，DNA甲基化状态调节韩牛LM组织的IMF和肌肉部分中成脂和生脂基因的组织特异性表达。
