Abstract：
αS1-Casein (encoded by the CSN1S1 gene) is associated with food allergy more than other milk protein components. Milk allergy caused by αS1-casein is derived from cow milk, goat milk and other ruminant milk. However, little is known about the transcription regulation of αS1-casein synthesis in dairy goats. This study aimed to investigate the regulatory roles of signal transducer and activator of transcription 5 (STAT5) on αS1-casein in goat mammary epithelial cells (GMEC). Deletion analysis showed that the core promoter region of CSN1S1 was located at -110 to -18 bp upstream of transcription start site, which contained two putative STAT5 binding sites (gamma-interferon activation site, GAS). Overexpression of STAT5a gene upregulated the mRNA level and the promoter activity of the CSN1S1 gene, and STAT5 inhibitor decreased phosphorylated STAT5 in the nucleus and CSN1S1 transcription activity. Further, GAS site-directed mutagenesis and chromatin immunoprecipitation (ChIP) assays revealed that GAS1 and GAS2 sites in the CSN1S1 promoter core region were binding sites of STAT5. Taken together, STAT5 directly regulates CSN1S1 transcription by GAS1 and GAS2 sites in GMEC, and the mutation of STAT5 binding sites could downregulate CSN1S1 expression and decrease αS1-casein synthesis, which provide the novel strategy for reducing the allergic potential of goat milk and improving milk quality in ruminants.
摘要：
αS1-酪蛋白（由CSN1S1基因编码）比其他乳蛋白成分与食物过敏更相关。由αS1-酪蛋白引起的牛奶过敏来自牛奶，羊奶和其他反刍动物奶。然而,对奶山羊中αS1-酪蛋白合成的转录调控知之甚少。本研究旨在探讨信号转导和转录激活因子5(STAT5)对山羊乳腺上皮细胞(GMEC)αS1-酪蛋白的调控作用。缺失分析表明，CSN1S1的核心启动子区位于转录起始位点上游-110至-18bp，其中包含两个推定的STAT5结合位点（γ-干扰素激活位点，气体）。STAT5a基因的过表达上调了CSN1S1基因的mRNA水平和启动子活性，STAT5抑制剂降低了STAT5在细胞核中的磷酸化和CSN1S1转录活性。Further,GAS定点诱变和染色质免疫沉淀（ChIP）分析显示，CSN1S1启动子核心区域的GAS1和GAS2位点是STAT5的结合位点。一起来看,STAT5通过GMEC中的GAS1和GAS2位点直接调控CSN1S1转录,STAT5结合位点的突变可以下调CSN1S1的表达并减少αS1-酪蛋白的合成，为反刍动物降低羊奶的潜在过敏和改善牛奶质量提供了新的策略。
