Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text Full Text (PDF, 1138K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Alert me to new content in the JGP Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Chien, L.-T. Articles by Hartzell, H. C. Search for Related Content PubMed Articles by Chien, L.-T. Articles by Hartzell, H. C. Social Bookmarking                            What's this?

Department of Cell Biology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322

Correspondence to H. Criss Hartzell: criss.hartzell{at}emory.edu

Mutations in human bestrophin-1 are linked to various kinds of retinal degeneration. Although it has been proposed that bestrophins are Ca²⁺-activated Cl^– channels, definitive proof is lacking partly because mice with the bestrophin-1 gene deleted have normal Ca²⁺-activated Cl^– currents. Here, we provide compelling evidence to support the idea that bestrophin-1 is the pore-forming subunit of a cell volume-regulated anion channel (VRAC) in Drosophila S2 cells. VRAC was abolished by treatment with RNAi to Drosophila bestrophin-1. VRAC was rescued by overexpressing bestrophin-1 mutants with altered biophysical properties and responsiveness to sulfhydryl reagents. In particular, the ionic selectivity of the F81C mutant changed from anionic to cationic when the channel was treated with the sulfhydryl reagent, sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES^–) (P_Cs/P_Cl = 0.25 for native and 2.38 for F81C). The F81E mutant was 1.3 times more permeable to Cs⁺ than Cl^–. The finding that VRAC was rescued by F81C and F81E mutants with different biophysical properties shows that bestrophin-1 is a VRAC in S2 cells and not simply a regulator or an auxiliary subunit. F81C overexpressed in HEK293 cells also exhibits a shift of ionic selectivity after MTSES^– treatment, although the effect is quantitatively smaller than in S2 cells. To test whether bestrophins are VRACs in mammalian cells, we compared VRACs in peritoneal macrophages from wild-type mice and mice with both bestrophin-1 and bestrophin-2 disrupted (best1^–/–/best2^–/–). VRACs were identical in wild-type and best1^–/–/best2^–/– mice, showing that bestrophins are unlikely to be the classical VRAC in mammalian cells.

© 2008 Chien and Hartzell This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jgp.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				Q. Xiao, K. Yu, Y.-y. Cui, and H. C. Hartzell Dysregulation of human bestrophin-1 by ceramide-induced dephosphorylation J. Physiol., September 15, 2009; 587(18): 4379 - 4391. [Abstract] [Full Text] [PDF]

				L. L. Marsey and J. P. Winpenny Bestrophin expression and function in the human pancreatic duct cell line, CFPAC-1 J. Physiol., May 15, 2009; 587(10): 2211 - 2224. [Abstract] [Full Text] [PDF]

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents