title: alpha(1C) (Ca(V)1.2) L-type calcium channel mediates mechanosensitive calcium regulation.
abstract: Smooth muscle exhibits mechanosensitivity independent of neural input, suggesting that mechanosensitive pathways reside within smooth muscle cells. The native L-type calcium current recorded from human intestinal smooth muscle is modulated by stretch. To define mechanosensitive mechanisms involved in the regulation of smooth muscle calcium entry, we cloned the alpha(1C) L-type calcium channel subunit (Ca(V)1.2) from human intestinal smooth muscle and expressed the channel in a heterologous system. This channel subunit retained mechanosensitivity when expressed alone or coexpressed with a beta(2) calcium channel subunit in HEK-293 or Chinese hamster ovary cells. The heterologously expressed human cardiac alpha(1C) splice form also demonstrated mechanosensitivity. Inhibition of kinase signaling did not affect mechanosensitivity of the native channel. Truncation of the alpha(1C) COOH terminus, which contains an inhibitory domain and a proline-rich domain thought to mediate mechanosensitive signaling from integrins, did not disrupt mechanosensitivity of the expressed channel. These data demonstrate mechanical regulation of calcium entry through molecularly identified L-type calcium channels in mammalian cells and suggest that the mechanosensitivity resides within the pore forming alpha(1C)-subunit.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Greg L
authors.initials: GL
authors.lastname: Lyford
authors.forename: Peter R
authors.initials: PR
authors.lastname: Strege
authors.forename: Allan
authors.initials: A
authors.lastname: Shepard
authors.forename: Yijun
authors.initials: Y
authors.lastname: Ou
authors.forename: Leonid
authors.initials: L
authors.lastname: Ermilov
authors.forename: Steven M
authors.initials: SM
authors.lastname: Miller
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Gibbons
authors.forename: James L
authors.initials: JL
authors.lastname: Rae
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Szurszewski
authors.forename: Gianrico
authors.initials: G
authors.lastname: Farrugia
mesh_terms: D000818:Animals; D016466:CHO Cells; D020746:Calcium Channels, L-Type / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics*; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007583:Jejunum / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000502:physiology; D018408:Patch-Clamp Techniques; D011312:Pressure; D020033:Protein Isoforms / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits; D017384:Sequence Deletion; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013314:Stress, Mechanical; D014162:Transfection
chemical_list: D020746:Calcium Channels, L-Type; D004791:Enzyme Inhibitors; C419385:L-type calcium channel alpha(1C); D020033:Protein Isoforms; D021122:Protein Subunits