Molecular mechanisms underlying inhibition of STIM1-Orai1-mediated Ca2+ entry induced by 2-aminoethoxydiphenyl borate

作者：Wei, Ming; Zhou, Yandong; Sun, Aomin; Ma, Guolin; He, Lian; Zhou, Lijuan; Zhang, Shuce; Liu, Jin; Zhang, Shenyuan L.; Gill, Donald L.^*; Wang, Youjun^*

来源：Pflugers Archiv-European Journal of Physiology, 2016, 468(11-12): 2061-2074.

DOI：10.1007/s00424-016-1880-z

• STIM1
• Orai1
• SOCE
• 2-APB
• Puncta
• FRET
• Calcium

Store-operated Ca2+ entry (SOCE) mediated by STIM1 and Orai1 is crucial for Ca2+ signaling and homeostasis in most cell types. 2-Aminoethoxydiphenyl borate (2-APB) is a well-described SOCE inhibitor, but its mechanisms of action remain largely elusive. Here, we show that 2-APB does not affect the dimeric state of STIM1, but enhances the intramolecular coupling between the coiled-coil 1 (CC1) and STIM-Orai-activating region (SOAR) of STIM1, with subsequent reduction in the formation of STIM1 puncta in the absence of Orai1 overexpression. 2-APB also inhibits Orai1 channels, directly inhibiting Ca2+ entry through the constitutively active, STIM1-independent Orai1 mutants, Orai1-P245T and Orai1-V102A. When unbound from STIM1, the constitutively active Orai1-V102C mutant is not inhibited by 2-APB. Thus, we used Orai1-V012C as a tool to examine whether 2-APB can also inhibit the coupling between STIM1 and Orai1. We reveal that the functional coupling between STIM1 and Orai1-V102C is inhibited by 2-APB. This inhibition on coupling is indirect, arising from 2-APB's action on STIM1, and it is most likely mediated by functional channel residues in the Orai1 N-terminus. Overall, our findings on this two-site inhibition mediated by 2-APB provide new understanding on Orai1-activation by STIM1, important to future drug design.

• 出版日期2016-11
• 单位北京师范大学