MyHC-AS调控猪骨胳肌II型MyHCs转录的机制研究

The expression pattern of porcine skeletal myosin heavy chains (MyHCs) is closely related with myofiber type and meat quality, but the regulatory mechanism about MyHCs expression remains largely unknown. Our previous data shown that MyHCs expression is primarily regulated at pre-transcriptional level, and there were antisense of type II MyHC (MyHC-AS) generated during porcine skeletal myofiber type switch. This project will work with IIa-AS (antisense of MyHC IIa), which changed most greatly during postnatal growth. We will pick up IIa-AS gene, verify its binding proteins, test the changes of DNA methylation and histone covalent modifications in MyHC IIa and (or) IIx promoters affected by IIa-AS, thus discuss the effects and related mechanism underlying MyHC IIa and (or) IIx transcription modulated by IIa-AS both in vivo and in vitro. Hopefully, this project could improve our understanding about the comprehensive regulatory network about skeletal MyHC expression and myofiber type switch, thus provide a theoretical support for improving pork quality in livestock industry.

猪骨胳肌肌球蛋白重链（myosin heavy chains，MyHCs）的表达与肌纤维类型及肌肉品质密切相关，但具体的调控机制目前尚不清楚。我们前期的研究发现猪MyHCs的表达主要在转录前水平受到调控，并且在肌纤维类型转化时II型MyHC基因簇会产生反义转录物MyHC-AS（antisense of MyHCs）。本项目从出生后表达变化差异显著的IIa-AS（antisense of MyHC IIa）入手，分析IIa-AS的基因特征、结合蛋白及其参与下的MyHC IIa和（或）IIx启动子组蛋白共价修饰和DNA甲基化的变化，从在体和离体两个方面解析IIa-AS的功能及其作用机制。本项目从一个崭新的角度探讨猪MyHCs转录及肌纤维类型转化的分子机理，为进一步改良猪肉品质提供理论依据。

本项目拟研究猪骨胳肌肌球蛋白重链（myosin heavy chain，MyHC）IIa的天然反义转录本调控II型MyHCs表达及肌纤维类型转化的分子机理，期望为改良猪肉品质提供理论依据。研究发现，猪II型MyHCs基因簇的内含子和基因间区域均存在转录活性，我们将MyHC IIa/x基因间区域的反向转录本命名为MyHC IIa/x-AS，进行深入研究。IIa/x-AS在肌肉中的表达量较高，在快肌中表达要高于慢肌，IIa/x-AS随着肌卫星分化表达量逐渐高。IIa/x-AS主要分布在细胞质内，没有编码潜能，预测可吸附miR-133b-3p等多个miRNAs。干扰IIa/x-AS能够降低miR-133b 靶基因IGF1R 的表达，提示可能存在MyHC IIa/x-AS--miR-133b--IGF1R轴，具体互作机制有待进一步验证。.在项目执行期间，发表SCI论文4篇，核心期刊1篇，培养学硕3名，专硕2名。