Downregulation of TMEM16A calcium-activated chloride channel contributes to cerebrovascular remodeling during hypertension by promoting basilar smooth muscle cell proliferation.
BACKGROUND
The Ca(2+)-activated chloride channel (CaCC) plays an important role in a variety of physiological functions. In vascular smooth muscle cells, CaCC is involved in the regulation of agonist-stimulated contraction and myogenic tone. The physiological functions of CaCC in blood vessels are not fully revealed because of the lack of specific channel blockers and the uncertainty concerning its molecular identity.


RESULTS
Whole-cell patch-clamp studies showed that knockdown of TMEM16A but not bestrophin-3 attenuated CaCC currents in rat basilar smooth muscle cells. The activity of CaCC in basilar smooth muscle cells isolated from 2-kidney, 2-clip renohypertensive rats was decreased, and CaCC activity was negatively correlated with blood pressure (n=25; P<0.0001) and medial cross-sectional area (n=24; P<0.0001) in basilar artery during hypertension. Both upregulation of CaMKII activity and downregulation of TMEM16A expression contributed to the reduction of CaCC in the hypertensive basilar artery. Western blot results demonstrated that angiotensin II repressed TMEM16A expression in basilar smooth muscle cells (n=6; P<0.01). Knockdown of TMEM16A facilitated and overexpression of TMEM16A inhibited angiotensin II-induced cell cycle transition and cell proliferation determined by flow cytometry and BrdU incorporation (n=6 in each group; P<0.05). TMEM16A affected cell cycle progression mainly through regulating the expression of cyclin D1 and cyclin E.


CONCLUSIONS
TMEM16A CaCC is a negative regulator of cell proliferation. Downregulation of CaCC may play an important role in hypertension-induced cerebrovascular remodeling, suggesting that modification of the activity of CaCC may be a novel therapeutic strategy for hypertension-associated cardiovascular diseases such as stroke.
Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Rd, Guangzhou, China.
Mi
M
Wang
Hui
H
Yang
Ling-Yun
LY
Zheng
Zheng
Z
Zhang
Yong-Bo
YB
Tang
Guan-Lei
GL
Wang
Yan-Hua
YH
Du
Xiao-Fei
XF
Lv
Jie
J
Liu
Jia-Guo
JG
Zhou
Yong-Yuan
YY
Guan
D000818:Animals; D000075369:Anoctamin-1; D001488:Basilar Artery / Q000378:metabolism / Q000473:pathology*; D000075002:Bestrophins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D018118:Chloride Channels / Q000378:metabolism*; D004195:Disease Models, Animal; D015536:Down-Regulation; D006973:Hypertension / Q000378:metabolism / Q000473:pathology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology*; D018408:Patch-Clamp Techniques; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley
C552942:ANO1 protein, rat; D000075369:Anoctamin-1; C568920:Best3 protein, rat; D000075002:Bestrophins; D018118:Chloride Channels; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2