IRBIT plays an important role in NHE3-mediated pH_i regulation in HSG cells

详细信息    查看全文

• 作者：Tien Manh Tran ; Moon-Yong Park ; Jiyeon Lee ; Jun-Seok Bae ; Sung-Min Hwang ; Se-Young Choi ; Katsuhiko Mikoshiba ; Kyungpyo Park
• 关键词：IRBIT ; pHi Recovery ; Na+/H+ exchangers ; HOE642 ; SPAK
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2013
• 出版时间：19 July, 2013
• 年：2013
• 卷：437
• 期：1
• 页码：18-22
• 全文大小：651 K

文摘

Expression of inositol-1,4,5-trisphosphate (IP₃) receptor-binding protein (IRBIT) has been reported in epithelial cells. However, its role in pH_i regulation is not well understood. In this study, we investigated the role of IRBIT in pH_i regulation, mediated by Na⁺/H⁺ exchangers (NHEs), in salivary glands. We measured pH_i recovery from cell acidification in BCECF-loaded salivary HSG cells. Western blot and co-immunoprecipitation (CO-IP) assays were also performed, showing that NHE1, 2 and 3 are expressed, and IRBIT binds to NHE3. HOE642, a specific NHE1 blocker, inhibited pH_i recovery, but 40 % pH_i recovery was still observed even at the highest concentration of HOE642. Furthermore, pretreatment of the cells with siIRBIT significantly inhibited pH_i recovery, indicating that NHE3 potentially plays a role in pH_i recovery as well. The amount of membrane-localized NHE3 and its interaction with IRBIT are also significantly increased by cell acidification. In addition, we found that Ste20p-related proline alanine-rich kinase (SPAK) reverses the effect of IRBIT on membrane NHE3 translocation. Taken together, we conclude that IRBIT plays an important role in pH_i regulation, mediated by NHE3, and further regulated by SPAK.