Genistein activates CFTR Cl- channels via a tyrosine kinase- and protein phosphatase-independent mechanism
Genistein activates CFTR Cl- channels via a tyrosine kinase- and protein phosphatase-independent mechanism
复制标题
DOI：
10.1152/ajpcell.1997.273.2.c747
复制
发表时间：
1997-08-01
影响因子：
5.5
通讯作者：
DeJonge, HR
中科院分区：
文献类型：
--
作者：
French, PJ;Bijman, J;DeJonge, HR
Previous studies have revealed an adenosine 3',5'-cyclic monophosphate (cAMP)-independent activation of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels by the tyrosine kinase inhibitor genistein. To further explore its mechanism of action, we have reconstituted genistein activation of CFTR in excised inside-out membrane patches. In the presence or absence of ATP, genistein appeared unable to open silent CFTR Cl- channels. However, on CFTR prephosphorylation by cAMP-dependent protein kinase (cAK), genistein enhanced CFTR activity by twofold, resulting from a prolonged burst duration. Genistein could also hyperactivate partially phosphorylated CFTR in the absence of cAK and therefore is different from 5'-adenylylimidodiphosphate, which required fully phosphorylated CFTR. Phosphatase-resistant thiophosphorylation likewise primed the CFTR Cl- channel for hyperactivation by genistein in the absence of cAK, Replacement of ATP by GTP as a hydrolyzable nucleotide triphosphate for CFTR did not impair the ability of genistein to activate thiophosphorylated CFTR, despite the fact that GTP is a poor substrate for tyrosine kinases. These findings argue against a role of protein phosphatases or tyrosine kinases but suggest a more direct interaction of genistein with CFTR, possibly at the level of the second nucleotide-binding domain.
