ABCMdb

PMID: 7522329

Becq F, Jensen TJ, Chang XB, Savoia A, Rommens JM, Tsui LC, Buchwald M, Riordan JR, Hanrahan JW
Phosphatase inhibitors activate normal and defective CFTR chloride channels.
Proc Natl Acad Sci U S A. 1994 Sep 13;91(19):9160-4., [PubMed]

Sentences

No. Mutations Sentence Comment

6 ABCC7 p.Gly551Asp ABCC7 p.Arg117His Most importantly, exposure ofmam- malian cells to phosphatase inhibitors alone activates CFTR channels that have disease-causing mutations, provided the mutant channels are present in the plasma membrane (R117H, G551D, and AF508 after cooling). Login to comment 106 ABCC7 p.Gly551Asp ABCC7 p.Arg117His We characterized the responses oftwo CFTR mutants that are processed similarly to wild type and are delivered to the plasma membrane; R117H, which causes a relatively mild (pancreatic-sufficient) form of CF (33, 34), and G551D, which does not respond to cAMP and causes severe disease (35, 36). Login to comment 107 ABCC7 p.Gly551Asp ABCC7 p.Gly551Asp ABCC7 p.Arg117His Both R117H and G551D channels were activated on CHO cells by exposure to (-)-p-bromotetramisole (PO = 0.14 ± 0.1, n = 5, and 0.35 ± 0.07, n = 4, respectively) in the absence of cAMP agonists (Fig. 3 B-E), even thoughforskolin alone did not open G551D channels in 14 of 14 trials (Fig. 3 C and E). Login to comment 108 ABCC7 p.Gly551Asp (-)-p-Bromotetramisole also slowed the rundown ofR117H and G551D in excised patches, as was observed with wild-type channels. Login to comment 109 ABCC7 p.Arg117His The mean number of mutant channels per patch that were activated in the presence of (-)-p-bromotetramisole (R117H, 2.0 ± 0.37,n = 7;G551D, 3.0 + 0.27, n = 31)was comparable to that determined for cells expressing wild-type CFTR (CHO, 4.0 ± 0.7, n = 11; airway; 3.2 ± 1.0, n = 5). Login to comment 110 ABCC7 p.Arg117His Single-channel conductances of R117H (5.7 ± 0.15 pS, n = 7) and GS51D (5.3 ± 0.37 pS, n = 10) channels were decreased slightly (Fig. 3D) compared with wild-type channels (6.8 ± 0.21 pS, n = 6, P < 0.05). Login to comment 141 ABCC7 p.Gly551Asp ABCC7 p.Gly551Asp This study reports strong activation of the G551D mutant in mammalian cells; the inability offorskolin to open G551D channels was apparently bypassed by inhibition of endogenous phosphatase activity. Login to comment 143 ABCC7 p.Gly551Asp ABCC7 p.Arg117His The activation of defective R117H and G551D channels by phosphatase inhib- I: I Physiology: Becq et aL A 71 I- - " Z '.1 L. 7r -I I.. i. Login to comment 151 ABCC7 p.Arg117His (A and B) Wild-type or R117H channel activity on cells incubated with (-)-p- bromotetramisole (Br-t, 1 mM) or IBMX (1 mM), respectively. Login to comment 155 ABCC7 p.Gly551Asp Note that G551D channels did not respond to forskolin but were activated by Br-t or IBMX. Login to comment