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Pflugers Arch February 1, 2010; 459 (3): 485-97.

ER-localized bestrophin 1 activates Ca2+-dependent ion channels TMEM16A and SK4 possibly by acting as a counterion channel.

Barro-Soria R , Aldehni F , Almaça J , Witzgall R , Schreiber R , Kunzelmann K .

Bestrophins form Ca(2+)-activated Cl(-) channels and regulate intracellular Ca(2+) signaling. We demonstrate that bestrophin 1 is localized in the endoplasmic reticulum (ER), where it interacts with stromal interacting molecule 1, the ER-Ca(2+) sensor. Intracellular Ca(2+) transients elicited by stimulation of purinergic P2Y(2) receptors in HEK293 cells were augmented by hBest1. The p21-activated protein kinase Pak2 was found to phosphorylate hBest1, thereby enhancing Ca(2+) signaling and activation of Ca(2+)-dependent Cl(-) (TMEM16A) and K(+) (SK4) channels. Lack of bestrophin 1 expression in respiratory epithelial cells of mBest1 knockout mice caused expansion of ER cisterns and induced Ca(2+) deposits. hBest1 is, therefore, important for Ca(2+) handling of the ER store and may resemble the long-suspected counterion channel to balance transient membrane potentials occurring through inositol triphosphate (IP(3))-induced Ca(2+) release and store refill. Thus, bestrophin 1 regulates compartmentalized Ca(2+) signaling that plays an essential role in Best macular dystrophy, inflammatory diseases such as cystic fibrosis, as well as proliferation.

PubMed ID: 19823864
Article link: Pflugers Arch

Species referenced: Xenopus laevis
Genes referenced: ano1 cdkn1a kcnn4 pak2

References [+] :
Aldehni, Bestrophin 1 promotes epithelial-to-mesenchymal transition of renal collecting duct cells. 2009, Pubmed