RT Journal Article
SR Electronic
T1 The Best Disease-Linked Cl<sup>−</sup> Channel <em>hBest1</em> Regulates Ca<sub>V</sub>1 (L-type) Ca<sup>2+</sup> Channels via src-Homology-Binding Domains
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 5660
OP 5670
DO 10.1523/JNEUROSCI.0065-08.2008
VO 28
IS 22
A1 Kuai Yu
A1 Qinghuan Xiao
A1 Guiying Cui
A1 Amy Lee
A1 H. Criss Hartzell
YR 2008
UL http://www.jneurosci.org/content/28/22/5660.abstract
AB Mutations in the bestrophin-1 (Best1) gene are linked to several kinds of macular degeneration in both humans and dogs. Although bestrophins have been shown clearly to be Cl− ion channels, it is controversial whether Cl− channel dysfunction can explain the diseases. It has been suggested that bestrophins are multifunctional proteins: they may regulate voltage-gated Ca2+ channels in addition to functioning as Cl− channels. Here, we show that human Best1 gene (hBest1) differentially modulates CaV1.3 (L-type) voltage-gated Ca2+ channels through association with the CaVβ subunit. In transfected human embryonic kidney 293 cells, hBest1 inhibited CaV1.3. Inhibition of CaV1.3 was not observed in the absence of the β subunit. Also, the hBest1 C terminus binds to CaVβ subunits, suggesting that the effect of hBest1 was mediated by the CaVβ subunit. The region of hBest1 responsible for the effect was localized to a region (amino acids 330–370) in the cytoplasmic C terminus that contains a predicted src-homology-binding domain that is not present in other bestrophin subtypes. Mutation of Pro330 and Pro334 abolished the effects of hBest1 on CaV1.3. The effect was specific to hBest1; it was not observed with mouse Best1 (mBest1), mBest2, or mBest3. Wild-type hBest1 and the disease-causing mutants R92S, G299R, and D312N inhibited CaV currents the same amount, whereas the A146K and G222E mutants were less effective. We propose that hBest1 regulates CaV channels by interacting with the CaVβ subunit and altering channel availability. Our findings reveal a novel function of bestrophin in regulation of CaV channels and suggest a possible mechanism for the role of hBest1 in macular degeneration.