MOLECULAR MECHANISMS REGULATING CALCIUM FLUX IN SALIVARY GLANDS

调节唾液腺钙通量的分子机制

• 批准号: 3775672
• 负责人: I S AMBUDKAR
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3775672
• 关键词: G protein; acinar cell; alpha adrenergic receptor; basolateral membrane; biological fluid transport; calcium; calcium flux; cold temperature; divalent cations; human tissue; laboratory rat; manganese; membrane permeability; muscarinic receptor; parotid gland; phospholipase C; protein structure function; saliva; salivary glands; secretion; stimulant /agonist; tissue /cell culture; trypsin

This project is directed towards understanding the processes which regulate cytosolic [Ca] in salivary gland cells. We are studying (i) receptor regulation of phosphatidylinositol bisphosphate-specific phospholipase C, (ii) regulation of Ca entry in salivary cells, and (iii) regulation of Ca flux in rat parotid gland basolateral membrane vesicles. Previously we have characterized a phosphatidyl-inositol- 4,5,bisphosphate specific phospholipase C enzyme in rat parotid gland membranes. In this reporting period we have shown that it is independently regulated by both muscarinic and alpha1-adrenergic receptors via a mechanism mediated by alpha subunits of the Gq/11family of G-proteins. Sustained Ca entry into parotid acini maintains a sustained elevation of Ca in the cytosol and thus facilitates prolonged fluid secretion. While we have earlier shown that Ca entry is correlated with the depletion of Ca from intracellular Ca stores, the exact mechanism which regulates this process is yet unclear. Using Mn as a substitute divalent cation, we have now shown that Ca entry into internal Ca pool depleted cells, via agonist stimulation, is very sensitive to temperature. Additionally, the pattern of its response to temperature distinguishes it from Mn entry into unstimulated acini. In a human salivary gland cell line, HSG, we have identified a Ca entry mechanism which is not regulated by the emptying of intracellular Ca stores, but depends on muscarinic receptor activation of G-protein(s). Consistent with our date with intact acini we have observed that Ca influx into isolated basolateral membrane vesicles is decreased at low temperature. We have observed that low temperature also protects Ca influx in vesicles against inactivation by trypsin and carbodiimides, which suggests that temperature induces a modification of the Ca influx pathway.

该项目是针对理解过程的 调节唾液腺细胞中的胞质[Ca]。 我们正在学习（i） 受体调节磷脂酰肌醇双磷酸特异性 磷脂酶C，（ii）调节唾液细胞中的Ca进入，以及 （iii）调节大鼠腮腺基底膜中的Ca通量 囊泡。 以前我们已经表征了磷脂酰肌醇 - 4,5，双磷酸特异性磷脂酶C酶在大鼠腮腺中 膜。 在此报告期内，我们表明是 由毒蕈碱和α1-肾上腺素能独立调节 通过GQ/11FAMILY的α亚基介导的机制 G蛋白。 持续的CA进入腮腺acini维护 ca在细胞质中的持续升高，从而促进延长 流体分泌。 虽然我们早些时候表明CA条目是 与细胞内CA存储的Ca耗竭相关， 调节此过程的确切机制尚不清楚。 使用Mn 作为替代阳离子的替代阳离子，我们现在表明CA进入 通过激动剂刺激，内​​部Ca池耗尽的细胞非常 对温度敏感。 另外，其响应的模式 为了使温度与MN进入未刺激的acini区分开。 在人类唾液腺细胞系HSG中，我们已经确定了一个CA进入 不受细胞内CA排空调节的机制 存储，但取决于G蛋白的毒蕈碱受体激活。 与我们完整的acini日期一致，我们已经观察到Ca 在低处涌入分离的基底外侧膜囊泡 温度。 我们已经观察到低温也可以保护CA 囊泡涌入胰蛋白酶和碳二酰亚胺灭活的囊泡， 这表明温度会导致CA涌入的修饰 路径。