Institute of Animal Science, Animal Breeding and Husbandry Group, University of Bonn, Germany.
Gene. 2011 Oct 15;486(1-2):8-14. doi: 10.1016/j.gene.2011.06.031. Epub 2011 Jul 2.
Among modern western pigs, Duroc (high meat fat ratio) and Pietrain (low meat fat ratio) breeds extensively utilized in commercial pork production differ extremely for their muscle phenotypes. The molecular mechanism, especially the epigenetic mechanism, underlying these breed-specific differences is poorly known. Myogenic factor 6 (MYF6) is the most abundantly expressed myogenic factor in adult muscle. Moreover, MYF6 tends to be expressed more highly in muscle tissue of the lean selection line and is supposed to be one promising candidate gene for growth- and meat quality-related traits in adult pigs. Six months old female Duroc and Pietrain pure breed pigs were used in this study. Protein and mRNA levels of MYF6 in loin eye muscle were determined by Western blotting and quantitative Real-time reverse transcription PCR (qRT-PCR), respectively. The DNA methylation status of the MYF6 5'-regulatory region was determined by bisulfite sequencing PCR (BSP). The global Histone 4 acetylation at lysines 5 (H4K5) and 8 (H4K8) were examined by Western blotting. Pietrain pigs exhibited significant higher expression of MYF6 and hypermethylated E2F1 binding element within MYF6 5'-regulatory region as compared with Duroc pigs. Significant elevation in DNA methyltransferase 1 (DNMT1) expression was observed in Pietrain pigs which are in agreement with hypermethylation of MYF6. Histone acetylation level at neither H4K5 nor H4K8 is significant between two breed pigs. Nevertheless, mRNA and protein expression of E2F1 were significantly elevated in the Pietrain breed. It is thus conceivable that the upregulation of MYF6 transcription in postnatal Pietrain pigs is not associated with cis-activation by epigenetic modification of MYF6 5'-regulatory region, but may be attributed to trans-activation through enriched expression of E2F1.
在现代西方猪中，杜洛克（高脂肪比例）和皮特兰（低脂肪比例）这两个广泛用于商业猪肉生产的品种，其肌肉表型差异极大。导致这些品种特异性差异的分子机制，特别是表观遗传机制，还知之甚少。肌生成因子 6（MYF6）是成年肌肉中表达最丰富的肌生成因子。此外，MYF6 在瘦肉选择系的肌肉组织中表达更高，被认为是成年猪生长和肉质相关性状的一个有前途的候选基因。本研究使用了 6 月龄雌性杜洛克和皮特兰纯种猪。通过 Western blot 法和实时定量 RT-PCR（qRT-PCR）分别测定腰眼肌中 MYF6 的蛋白和 mRNA 水平。通过亚硫酸氢盐测序 PCR（BSP）测定 MYF6 5'调控区的 DNA 甲基化状态。通过 Western blot 法检测组蛋白 4 在赖氨酸 5（H4K5）和 8（H4K8）的乙酰化状态。与杜洛克猪相比，皮特兰猪的 MYF6 表达显著升高，且 MYF6 5'调控区的 E2F1 结合元件发生超甲基化。在皮特兰猪中观察到 DNA 甲基转移酶 1（DNMT1）的表达显著升高，与 MYF6 的超甲基化一致。两种品种猪的 H4K5 和 H4K8 处的组蛋白乙酰化水平均无显著差异。然而，E2F1 的 mRNA 和蛋白表达在皮特兰品种中显著升高。因此，可以想象，皮特兰猪在出生后 MYF6 转录的上调与 MYF6 5'调控区的表观遗传修饰的顺式激活无关，而是可能归因于 E2F1 表达丰富的反式激活。
