title: Urotensin-II receptor stimulation of cardiac L-type Ca2+ channels requires the βγ subunits of Gi/o-protein and phosphatidylinositol 3-kinase-dependent protein kinase C β1 isoform.
abstract: Recent studies have demonstrated that urotensin-II (U-II) plays important roles in cardiovascular actions including cardiac positive inotropic effects and increasing cardiac output. However, the mechanisms underlying these effects of U-II in cardiomyocytes still remain unknown. We show by electrophysiological studies that U-II dose-dependently potentiates L-type Ca(2+) currents (ICa,L) in adult rat ventricular myocytes. This effect was U-II receptor (U-IIR)-dependent and was associated with a depolarizing shift in the voltage dependence of inactivation. Intracellular application of guanosine-5'-O-(2-thiodiphosphate) and pertussis toxin pretreatment both abolished the stimulatory effects of U-II. Dialysis of cells with the QEHA peptide, but not scrambled peptide SKEE, blocked the U-II-induced response. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin as well as the class I PI3K antagonist CH132799 blocked the U-II-induced ICa,L response. Protein kinase C antagonists calphostin C and chelerythrine chloride as well as dialysis of cells with 1,2bis(2aminophenoxy)ethaneN,N,N',N'-tetraacetic acid abolished the U-II-induced responses, whereas PKCα inhibition or PKA blockade had no effect. Exposure of ventricular myocytes to U-II markedly increased membrane PKCβ1 expression, whereas inhibition of PKCβ1 pharmacologically or by shRNA targeting abolished the U-II-induced ICa,L response. Functionally, we observed a significant increase in the amplitude of sarcomere shortening induced by U-II; blockade of U-IIR as well as PKCβ inhibition abolished this effect, whereas Bay K8644 mimicked the U-II response. Taken together, our results indicate that U-II potentiates ICa,L through the βγ subunits of Gi/o-protein and downstream activation of the class I PI3K-dependent PKCβ1 isoform. This occurred via the activation of U-IIR and contributes to the positive inotropic effect on cardiomyocytes.
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Geriatrics and Institute of Neuroscience, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China.
authors: Yuan
authors: Y
authors: Zhang
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China.
authors: Jiaoqian
authors: J
authors: Ying
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Dermatology and Allergic Diseases, University of Ulm, Ulm 89081, Germany, and.
authors: Dongsheng
authors: D
authors: Jiang
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China.
authors: Zhigang
authors: Z
authors: Chang
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, National Shanghai Center for New Drug Safety Evaluation and Research, Shanghai 201203, China.
authors: Hua
authors: H
authors: Li
authors: Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China.
authors: Guoqiang
authors: G
authors: Zhang
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China.
authors: Shan
authors: S
authors: Gong
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China.
authors: Xinghong
authors: X
authors: Jiang
authors: From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, taoj@suda.edu.cn.
authors: Jin
authors: J
authors: Tao
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020013:Calcium Signaling; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D006352:Heart Ventricles / Q000166:cytology; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism; D018408:Patch-Clamp Techniques; D019869:Phosphatidylinositol 3-Kinases; D064546:Protein Kinase C beta / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D012518:Sarcomeres / Q000502:physiology; D014579:Urotensins / Q000502:physiology
chemical_list: D020746:Calcium Channels, L-Type; D007527:Isoenzymes; D021122:Protein Subunits; D043562:Receptors, G-Protein-Coupled; D014579:Urotensins; C512325:urotensin II receptor, mouse; C029677:urotensin II; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D064546:Protein Kinase C beta; D019206:GTP-Binding Protein alpha Subunits, Gi-Go
keywords: Calcium Channel; Cardiovascular; G-protein-coupled Receptor (GPCR); Patch Camp; Protein Kinase; Signal Transduction