Caveolae link Ca(V)3.2 channels to BK(Ca)-mediated feedback in vascular smooth muscle

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Item Type:	Article
Title:	Caveolae link Ca(V)3.2 channels to BK(Ca)-mediated feedback in vascular smooth muscle
Creators Name:	Hashad, A.M., Harraz, O.F., Brett, S.E., Romero, M., Kassmann, M., Puglisi, J.L., Wilson, S.M., Gollasch, M. and Welsh, D.G.
Abstract:	OBJECTIVE: This study examined whether caveolae position Ca(V)3.2 (T-type Ca2+ channel encoded by the α-3.2 subunit) sufficiently close to RyR (ryanodine receptors) for extracellular Ca(2+) influx to trigger Ca(2+) sparks and large-conductance Ca(2+)-activated K(+) channel feedback. APPROACH AND RESULTS: Using smooth muscle cells from mouse mesenteric arteries, the proximity ligation assay confirmed that Ca(V)3.2 reside within 40 nm of caveolin 1, a key caveolae protein. Methyl-β-cyclodextrin, a cholesterol depleting agent that disrupts caveolae, suppressed Ca(V)3.2 activity along with large-conductance Ca(2+)-activated K(+)–mediated spontaneous transient outward currents in cells from C57BL/6 but not Ca(V)3.2(−/−) mice. Genetic deletion of caveolin 1, a perturbation that prevents caveolae formation, also impaired spontaneous transient outward current production but did so without impairing Ca(2+) channel activity, including Ca(V)3.2. These observations indicate a mistargeting of Ca(V)3.2 in caveolin 1(−/−) mice, a view supported by a loss of Ni(2+)-sensitive Ca(2+) spark generation and colocalization signal (Ca(V)3.2-RyR) from the proximity ligation assay. Vasomotor and membrane potential measurements confirmed that cellular disruption of the Ca(V)3.2-RyR axis functionally impaired the ability of large-conductance Ca(2+)-activated K(+) to set tone in pressurized caveolin 1(−/−) arteries. CONCLUSIONS: Caveolae play a critical role in protein targeting and preserving the close structural relationship between Ca(V)3.2 and RyR needed to drive negative feedback control in resistance arteries.
Keywords:	Caveolae, Caveolin 1, Membrane Potential, Sarcoplasmic Reticulum, Animals, Mice
Source:	Arteriosclerosis Thrombosis and Vascular Biology
ISSN:	1079-5642
Publisher:	American Heart Association
Volume:	38
Number:	10
Page Range:	2371-2381
Date:	October 2018
Official Publication:	https://doi.org/10.1161/ATVBAHA.118.311394
PubMed:	View item in PubMed

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