title: cAbl tyrosine kinase mediates reactive oxygen species- and caveolin-dependent AT1 receptor signaling in vascular smooth muscle: role in vascular hypertrophy.
abstract: Important output signals of the angiotensin subtype 1 receptor (AT1R) in vascular smooth muscle cells (VSMCs) are mediated by angiotensin II (Ang II)-stimulated transactivation of the epidermal growth factor receptor (EGF-R), which is critical for vascular hypertrophy. Ang II-induced EGF-R transactivation is mediated through cSrc, a proximal target of reactive oxygen species (ROS) derived from NAD(P)H oxidase (NOX) and is dependent on AT(1)R trafficking through caveolin1 (Cav1)-enriched lipid rafts. Underlying molecular mechanisms are incompletely understood. The nonreceptor tyrosine kinase, proto-oncogene cAbl is a substrate of Src and is a major mediator for ROS-dependent tyrosine phosphorylation of Cav1. We thus hypothesized that cAbl is important for ROS-, cSrc-, and Cav1-dependent growth-related AT1R signal transduction. Here we show that Ang II induces tyrosine phosphorylation of cAbl in rat VSMCs and mouse aorta, and that Ang II promotes association of cAbl with AT(1)R, both of which are Src-dependent. Pretreatment of rat VSMCs with the NOX inhibitor diphenylene iodonium or the antioxidants N-acetylcysteine or ebselen significantly inhibited Ang II-induced cAbl phosphorylation. Cell fractionation shows that both EGF-Rs and cAbl are found basally in Cav1-enriched membrane fractions. Knockdown of cAbl protein using small interference RNA inhibits Ang II-stimulated: (1) trafficking of AT1R into, and EGF-R out of, Cav1-enriched lipid rafts; (2) EGF-R transactivation; (3) appearance of the transactivated EGF-R and phospho-Cav1 at focal adhesions; and (4) vascular hypertrophy. These studies provide a novel role of cAbl in the spatial and temporal organization of growth-related AT1R signaling in VSMCs and suggest that cAbl may be generally important in signaling of G-protein coupled receptors.
authors.affiliation: Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Ga 30322, USA. mfukai@emory.edu
authors.forename: Masuko
authors.initials: M
authors.lastname: Ushio-Fukai
authors.forename: Lian
authors.initials: L
authors.lastname: Zuo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ikeda
authors.forename: Taiki
authors.initials: T
authors.lastname: Tojo
authors.forename: Nikolay A
authors.initials: NA
authors.lastname: Patrushev
authors.forename: R Wayne
authors.initials: RW
authors.lastname: Alexander
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D066246:ErbB Receptors / Q000378:metabolism; D006984:Hypertrophy; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology; D021962:Membrane Microdomains / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology*; D032389:Myocytes, Smooth Muscle / Q000473:pathology*; D010766:Phosphorylation; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D016315:Proto-Oncogene Proteins c-abl / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1 / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D015533:Transcriptional Activation; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D066246:ErbB Receptors; D016315:Proto-Oncogene Proteins c-abl; D019061:src-Family Kinases; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C516727:Ptpn11 protein, rat