title: Caveolin-1 facilitates the direct coupling between large conductance Ca2+-activated K+ (BKCa) and Cav1.2 Ca2+ channels and their clustering to regulate membrane excitability in vascular myocytes.
abstract: L-type voltage-dependent Ca(2+) channels (LVDCC) and large conductance Ca(2+)-activated K(+) channels (BKCa) are the major factors defining membrane excitability in vascular smooth muscle cells (VSMCs). The Ca(2+) release from sarcoplasmic reticulum through ryanodine receptor significantly contributes to BKCa activation in VSMCs. In this study direct coupling between LVDCC (Cav1.2) and BKCa and the role of caveoline-1 on their interaction in mouse mesenteric artery SMCs were examined. The direct activation of BKCa by Ca(2+) influx through coupling LVDCC was demonstrated by patch clamp recordings in freshly isolated VSMCs. Using total internal reflection fluorescence microscopy, it was found that a large part of yellow fluorescent protein-tagged BKCa co-localized with the cyan fluorescent protein-tagged Cav1.2 expressed in the plasma membrane of primary cultured mouse VSMCs and that the two molecules often exhibited FRET. It is notable that each BKα subunit of a tetramer in BKCa can directly interact with Cav1.2 and promotes Cav1.2 cluster in the molecular complex. Furthermore, caveolin-1 deficiency in knock-out (KO) mice significantly reduced not only the direct coupling between BKCa and Cav1.2 but also the functional coupling between BKCa and ryanodine receptor in VSMCs. The measurement of single cell shortening by 40 mm K(+) revealed enhanced contractility in VSMCs from KO mice than wild type. Taken together, caveolin-1 facilitates the accumulation/clustering of BKCa-LVDCC complex in caveolae, which effectively regulates spatiotemporal Ca(2+) dynamics including the negative feedback, to control the arterial excitability and contractility.
authors.affiliation: From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan and.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hisao
authors.initials: H
authors.lastname: Yamamura
authors.forename: Susumu
authors.initials: S
authors.lastname: Ohya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Imaizumi
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; C495541:Cav1 protein, mouse; D051242:Caveolin 1; C419385:L-type calcium channel alpha(1C); D051036:Large-Conductance Calcium-Activated Potassium Channels; D021122:Protein Subunits; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium
keywords: Calcium Signaling; Caveolin; Fluorescence Resonance Energy Transfer (FRET); Imaging; L-type Voltage-dependent Calcium Channel; Large Conductance Calcium-activated Potassium Channel; Single Molecule Biophysics; Total Internal Reflection Fluorescent Microscopy; Vascular Smooth Muscle Cells