Towards understanding physiological function of TRPM6/7 like channel in a HCO_3-secreting epithelium

旨在了解 HCO_3 分泌上皮细胞中 TRPM6/7 样通道的生理功能

• 批准号: 18590199
• 负责人: ISHIKAWA Toru
• 金额: $ 2.5万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18590199/
• 关键词: Bovine parotid; Bicarbonate secretion; Cation channel; 陽イオンチャネル

Ruminant parotid glands secrete continuously large volumes of HCO_3-rich saliva even at resting, but the underlying molecular mechanism remains unclear. Since ruminant parotid secretory cells contain several ion channels that can be regulated by intracellular Ca^<2+> and Mg^<2+>, resting cellular homeostasis of these divalent cations might also play an important role in the continuous HCO_3 secretion. Towards better understanding the mechanism of the parotid HCO_3 secretion, this project focused on TRPM6 and TRPM7 that are known to be cation channels permeable to divalent cations such as Ca^<2+> and Mg^<2+>. Using electrophysiological and molecular biological techniques, it was found that 1) bovine parotid acinar cells exhibit a membrane current, which is sensitive to intracellular Mg^<2+> as reported for recombinant TRPM7 and TRPM6 currents, 2) bovine parotid cells express transcripts of TRPM6 and TRPM7, 3) TRPM7 that was cloned from bovine parotid was functional in a heterologous expression system. These basic results would be useful for future studies to address the issues as to not only the molecular basis and cellular regulation of the native TRPM6/7-like conductance in bovine parotid acinar cells, but also the role of TRPM6 and TRPM7 in epithelial HCO_3 secretion.

反刍动物腮腺即使在静息状态下也能持续分泌大量富含HCO_3的唾液，但其分子机制尚不清楚。由于反刍动物腮腺分泌细胞内含有多种离子通道，这些离子通道可受细胞内Ca^2+和Mg^2+的调节，因此这些二价阳离子的静息细胞内稳态可能在HCO_3的持续分泌中也起着重要作用。为了更好地理解腮腺HCO_3分泌的机制，本项目集中于TRPM 6和TRPM 7，这两个已知的阳离子通道可渗透二价阳离子，如Ca^2+和Mg^2+。利用电生理学和分子生物学技术发现：1）牛腮腺腺泡细胞具有对胞内Mg^2+敏感的膜电流，如重组TRPM 7和TRPM 6电流所报道的; 2）牛腮腺细胞表达TRPM 6和TRPM 7的转录本; 3）从牛腮腺克隆的TRPM 7在异源表达系统中具有功能。这些基本结果将有助于未来的研究，不仅可以解决牛腮腺腺泡细胞中天然TRPM 6/7样电导的分子基础和细胞调节问题，还可以解决TRPM 6和TRPM 7在上皮HCO 3分泌中的作用问题。