Coupling factor 6 enhances Src-mediated responsiveness to angiotensin II in resistance arterioles and cells.
OBJECTIVE
Coupling factor 6 (CF6) induces hypertension by attenuating the endothelial generation of prostacyclin. However, intracellular signalling of CF6 in the resistance arteriole vascular smooth muscle cells (VSMCs) that are directly related to vasoconstriction has not been determined. Here we investigated the direct effect of exogenous CF6 on Ca2+ signalling in cultured VSMCs and the in vivo role of endogenous CF6 in the genesis of hypertension using CF6 transgenic (TG) mice.


RESULTS
CF6 induced a monophasic increase in the intracellular free Ca2+ concentration ([Ca2+]i) through nifedipine-sensitive Ca2+ channels in A7r5 cells, a cell line of VSMCs, and enhanced the angiotensin II-induced spike phase of [Ca2+]i to a greater degree in VSMCs derived from spontaneously hypertensive rats (SHRs). In the mesenteric arterioles obtained from CF6-TG mice that manifested hypertension, angiotensin II-induced vasoconstriction was enhanced, compared with wild-type mice, and its enhancement was abolished by an anti-CF6 antibody. Pre-treatment with PP1, a tyrosine kinase c-Src inhibitor, blocked CF6-induced increase in Ca2+ signalling in VSMCs and vasoconstriction in TG mice. The receptor of CF6 was F1 motor of adenosine triphosphate (ATP) synthase with a higher affinity in SHRs. CF6 decreased intracellular pH via activation of ATPase activity and led to c-Src activation to a greater degree in SHR-derived VSMCs.


CONCLUSIONS
CF6 causes hypertension by directly enhancing Ca2+ signalling in VSMCs and vasoconstriction in the mesenteric arteriolar network via c-Src activation.
Osanai
Tomohiro
T
Department of Cardiology, Hirosaki University Graduate School of Medicine, 5 Zaifu-Cho, Hirosaki 036-8562, Japan. osanait@cc.hirosaki-u.ac.jp
Tomita
Hirofumi
H
Kushibiki
Motoi
M
Yamada
Masahiro
M
Tanaka
Makoto
M
Ashitate
Toshihiro
T
Echizen
Takashi
T
Katoh
Chisato
C
Magota
Koji
K
Okumura
Ken
K
D000255:Adenosine Triphosphate / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001160:Arterioles / Q000201:enzymology / Q000503:physiopathology; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D006973:Hypertension / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008643:Mesentery / Q000098:blood supply*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D025261:Mitochondrial Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D010086:Oxidative Phosphorylation Coupling Factors / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013997:Time Factors; D014655:Vascular Resistance; D014661:Vasoconstriction; D019061:src-Family Kinases / Q000378:metabolism*
D015220:Calcium Channels; D010086:Oxidative Phosphorylation Coupling Factors; D000804:Angiotensin II; D000255:Adenosine Triphosphate; D019061:src-Family Kinases; C000628217:F(6) ATPase; D025261:Mitochondrial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases