Caveolar remodeling is a critical mechanotransduction mechanism of the stretch-induced L-type Ca2+ channel activation in vascular myocytes
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Activation of L-type voltage-dependent Ca2+ channels (VDCCL) by membrane stretch contributes to many biological responses such as myogenic contraction of arteries. However, mechanism for the stretch-induced VDCCL activation is unclear. In this study, we examined the hypothesis that caveolar remodeling and its related signaling cascade contribute to the stretch-induced activation of VDCCL in rat mesenteric arterial smooth muscle cells. The VDCCL currents were recorded with nystatin-perforated or with conventional whole-cell patch-clamp technique. Hypotonic (~230 mOsm) swelling-induced membrane stretch reversibly increased the VDCCL currents. Electron microscope and confocal imaging analysis revealed that both hypotonic swelling and cholesterol depletion by methyl-β-cychlodextrin (MβCD) similarly disrupted the caveolae structure and translocated caveolin-1 (Cav-1) from membrane to cytosolic space. Accordingly, MβCD also increased VDCCL currents. Moreover, subsequent hypotonic swelling after MβCD treatment failed to increase the VDCCL currents further. Western blotting experiments revealed that hypotonic swelling phosphorylated Cav-1 and JNK. Inhibitors of tyrosine kinases (genistein) and JNK (SP00125) prevented the swelling-induced facilitation of VDCCL currents. Knockdown of Cav-1 by small interfering RNA blocked both the VDCCL current facilitation by stretch and the related phosphorylation of JNK. Taken together, the results suggest that membrane stretch is transduced to the facilitation of VDCCL currents via caveolar structure-dependent tyrosine phosphorylation of Cav-1 and subsequent activation of JNK in rat mesenteric arterial myocytes.
KeywordsCaveolae Stretch Voltage-dependent calcium channel Caveolin C-Jun N-terminal kinase
This research was supported by the Pioneer Research Center Program (2011-0027921) and by Basic Science Research Programs (2015R1C1A1A02036887, 2016R1A2B4014795 and NRF-2009-0071242) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning.
Compliance with ethical standards
All experiments were conducted in accordance with the National Institutes of Health guidelines for the care and use of animals, and the institutional animal care and use committee of Konkuk University approved this study
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