我国牦牛占世界牦牛总量92%，牦牛的研究主要在我国进行。近年牦牛养殖由传统放牧向冷季精料补饲及舍饲生产转变，牦牛瘤胃酸中毒成了新的生产问题和科研课题。瘤胃酸中毒导致瘤胃上皮细胞紧密连接破坏，在人和鼠等研究表明非肌肌球蛋白IIA（NMIIA）磷酸化对肠道上皮紧密连接有重要调控作用。本课题组研究发现瘤胃发育不良牦牛瘤胃上皮NMIIA基因和JNK磷酸化激酶表达量升高，但NMIIA对瘤胃上皮紧密连接的调控机制不清楚。本项目假设瘤胃酸中毒可影响NMIIA不同位点磷酸化，差异性激活下游JNK信号通路，影响瘤胃上皮细胞紧密连接。项目拟通过牦牛瘤胃上皮细胞原代培养建立细胞屏障模型，研究NMIIA的C端T1800-S1808、S1916-S1937和S1943位点磷酸化对不同pH和LPS浓度的应答，揭示JNK信号通路对NMIIA磷酸化的响应网络，阐明NMIIA磷酸化对瘤胃酸中毒牦牛瘤胃上皮紧密连接影响机理。

Approximately 92% of the world’s total yak population are distributed in China. Studies on yaks are mainly carried out in China. Recently, yaks farming is transforming from the traditional grazing system to the concentrate supplementary feeding and stall-feeding fattening in the cold season. The rumen acidosis in yaks farming becomes a new production problem and research subject. Rumen acidosis leads to the damage of rumen epithelial cellular tight junctions. Studies on human and mouses indicated that non-muscle myosin IIA (NM IIA) phosphorylation had important regulatory functions on the tight junctions of the intestinal epithelium. Our team has found that NMIIA and JNK phosphorylated kinase mRNA expressions in the ruminal epithelium of yaks with rumen maldevelopment were significantly increased, but the mechanism of NMIIA regulated on the tight junctions of ruminal epithelium was still unclear. We hypothesize that rumen acidosis can influence the phosphorylation of different sites on the NMIIA, differentially activate the downstream JNK signal pathway and impact on the tight junctions of rumen epithelium. Our project plan to establish a model of epithelial cell monolayer barrier via the yak’s rumen epithelial cells primary culture, investigate different Phosphorylation of sites on the C-terminus of NMIIA, included T1800-S1808, S1916-S1937 and S1943, response to the different pH and LPS concentrations, uncover the downstream signal network of JNK response to the NMIIA phosphorylation, and reveal the influence mechanism of non-muscle myosin IIA phosphorylation on the rumen epithelial cellular tight junctions of yaks under rumen acidosis.