The type II Na/Pi co-transporter (NaPi2b), encoded by the solute carrier (SLC) transporter 34A2 (SLC34A2), is responsible for calcium (Ca) and phosphorus (P) homeostasis. Unbalanced Ca/P metabolism induces mastitis in dairy cows. However, the specific role of SLC34A2 in regulating this imbalance in Holstein cows with clinical mastitis (CM) remains unclear. The aim of this study was to investigate the role of SLC34A2 and identify differentially expressed proteins (DEPs) that interact with SLC34A2 and are associated with Ca/P metabolism in dairy cows with CM. Immunohistochemical and immunofluorescence staining results showed that SLC34A2 was located primarily in the mammary epithelial cells of the mammary alveoli in both the control (healthy cows, Con/C) and CM groups. Compared to the Con/C group, the relative expression of the SLC34A2 gene and protein were significantly downregulated in the CM group. We identified 12 important DEPs included in 11 GO terms and two pathways interacting with SLC34A2 using data-independent acquisition proteomics. The PPI (protein-and-protein interaction) network results suggested that these DEPs were associated with ion metabolism and homeostasis, especially SLC34A2. These results demonstrate that SLC34A2 downregulation is negatively correlated with the occurrence and development of CM in Holstein cows, providing a basis for exploring the function and regulatory mechanism of SLC34A2 in Ca/P metabolism and homeostasis in Holstein cows with CM.

中文翻译：

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SLC34A2 靶向乳腺钙/磷稳态并参与奶牛临床乳腺炎的发生

II 型 Na/Pi 协同转运蛋白 (NaPi2b) 由溶质载体 (SLC) 转运蛋白 34A2 (SLC34A2) 编码，负责钙 (Ca) 和磷 (P) 稳态。 Ca/P代谢不平衡会诱发奶牛乳腺炎。然而，SLC34A2 在调节患有临床乳腺炎 (CM) 的荷斯坦奶牛中这种不平衡的具体作用仍不清楚。本研究的目的是研究 SLC34A2 的作用，并鉴定与 SLC34A2 相互作用并与 CM 奶牛 Ca/P 代谢相关的差异表达蛋白 (DEP)。免疫组织化学和免疫荧光染色结果显示，在对照组（健康奶牛，Con/C）和CM组中，SLC34A2主要定位于乳腺泡的乳腺上皮细胞中。与Con/C组相比，CM组SLC34A2基因和蛋白的相对表达量显着下调。我们使用数据独立的采集蛋白质组学确定了 11 个 GO 术语中包含的 12 个重要 DEP 以及与 SLC34A2 相互作用的两条通路。 PPI（蛋白质与蛋白质相互作用）网络结果表明这些 DEP 与离子代谢和稳态相关，尤其是 SLC34A2。这些结果表明SLC34A2的下调与荷斯坦奶牛CM的发生和发展呈负相关，为探讨SLC34A2在荷斯坦奶牛CM奶牛Ca/P代谢和稳态中的功能和调节机制提供了基础。