title: ATP-induced mitogenesis is mediated by cyclic AMP response element-binding protein-enhanced TRPC4 expression and activity in human pulmonary artery smooth muscle cells.
abstract: Extracellular ATP and intracellular cyclic AMP response element-binding protein (CREB, a transcription factor) promote cell proliferation in many cell types. The canonical transient receptor potential (TRPC) channels, which putatively participate in forming store- and receptor-operated Ca2+ channels, have been implicated in the pulmonary vascular remodeling processes. A link between extracellular ATP, CREB activation, and TRPC4 channel expression and activity has not been shown in human pulmonary artery smooth muscle cells (PASMC). Long-term (24-48 h) treatment of human PASMC with a low dose (100 microM) of ATP, which did not trigger a transient rise in free cytosolic Ca2+ concentration ([Ca2+]i) when applied acutely to the cells, caused marked increases in CREB phosphorylation and TRPC4 protein expression. The time course indicated that the ATP-mediated CREB phosphorylation preceded TRPC4 upregulation, whereas transfection of a nonphosphorylatable CREB mutant abolished ATP-mediated TRPC4 expression. Furthermore, treatment of human PASMC with ATP also enhanced the amplitude of capacitative Ca2+ entry (CCE) induced by passive store depletion, whereas the small interfering RNA specifically targeting TRPC4 attenuated ATP-mediated increases in TRPC4 expression and CCE amplitude and inhibited ATP-induced PASMC proliferation. These data suggest that low-dose ATP exerts part of its mitogenic effect in human PASMC via CREB-mediated upregulation of TRPC4 channel expression and activity and the subsequent increase in CCE and [Ca2+]i.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0725, USA. xiyuan@ucsd.edu
authors.forename: Shen
authors.initials: S
authors.lastname: Zhang
authors.forename: Carmelle V
authors.initials: CV
authors.lastname: Remillard
authors.forename: Ivana
authors.initials: I
authors.lastname: Fantozzi
authors.forename: Jason X-J
authors.initials: JX
authors.lastname: Yuan
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002455:Cell Division; D017362:Cyclic AMP Response Element-Binding Protein / Q000187:drug effects / Q000378:metabolism*; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D011651:Pulmonary Artery / Q000187:drug effects / Q000378:metabolism; D050052:TRPC Cation Channels; D013997:Time Factors
chemical_list: D015220:Calcium Channels; D017362:Cyclic AMP Response Element-Binding Protein; D050052:TRPC Cation Channels; D000255:Adenosine Triphosphate; D002118:Calcium