Referenced in: none

Automatically associated channels: Cav1.2

Title: Cyclosporin and Timothy syndrome increase mode 2 gating of CaV1.2 calcium channels through aberrant phosphorylation of S6 helices.

Authors: Christian Erxleben, Yanhong Liao, Saverio Gentile, David Chin, Claudio Gomez-Alegria, Yasuo Mori, Lutz Birnbaumer, David L Armstrong

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2006 Mar 7 , 103, 3932-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/16537462

Abstract
Calcium channels in the plasma membrane rarely remain open for much more than a millisecond at any one time, which avoids raising intracellular calcium to toxic levels. However, the dihydropyridine-sensitive calcium channels of the CaV1 family, which selectively couple electrical excitation to endocrine secretion, cardiovascular contractility, and neuronal transcription, have a unique second mode of gating, "mode 2," that involves frequent openings of much longer duration. Here we report that two human conditions, cyclosporin neurotoxicity and Timothy syndrome, increase mode 2 gating of the recombinant rabbit CaV1.2 channel. In each case, mode 2 gating depends on a Ser residue at the cytoplasmic end of the S6 helix in domain I (Ser-439, Timothy syndrome) or domain IV (Ser-1517, cyclosporin). Both Ser reside in consensus sequences for type II calmodulin-dependent protein kinase. Pharmacologically inhibiting type II calmodulin-dependent protein kinase or mutating the Ser residues to Ala prevents the increase in mode 2 gating. We propose that aberrant phosphorylation, or "phosphorylopathy," of the CaV1.2 channel protein contributes to the excitotoxicity associated with Timothy syndrome and with chronic cyclosporin treatment of transplant patients.