title: Ligand-Independent Activation of Platelet-Derived Growth Factor Receptor β during Human Immunodeficiency Virus-Transactivator of Transcription and Cocaine-Mediated Smooth Muscle Hyperplasia.
abstract: Our previous study supports an additive effect of cocaine to human immunodeficiency virus infection in the development of pulmonary arteriopathy through enhancement of proliferation of pulmonary smooth muscle cells (SMCs), while also suggesting involvement of platelet-derived growth factor receptor (PDGFR) activation in the absence of further increase in PDGF-BB ligand. Redox-related signaling pathways have been shown to regulate tyrosine kinase receptors independent of ligand binding, so we hypothesized that simultaneous treatment of SMCs with transactivator of transcription (Tat) and cocaine may be able to indirectly activate PDGFR through modulation of reactive oxygen species (ROS) without the need for PDGF binding. We found that blocking the binding of ligand using suramin or monoclonal IMC-3G3 antibody significantly reduced ligand-induced autophosphorylation of Y1009 without affecting ligand-independent transphosphorylation of Y934 residue on PDGFRβ in human pulmonary arterial SMCs treated with both cocaine and Tat. Combined treatment of human pulmonary arterial SMCs with cocaine and Tat resulted in augmented production of superoxide radicals and hydrogen peroxide when compared with either treatment alone. Inhibition of this ROS generation prevented cocaine- and Tat-mediated Src activation and transphosphorylation of PDGFRβ at Y934 without any changes in phosphorylation of Y1009, in addition to attenuation of smooth muscle hyperplasia. Furthermore, pretreatment with an Src inhibitor, PP2, also suppressed cocaine- and Tat-mediated enhanced Y934 phosphorylation and smooth muscle proliferation. Finally, we report total abrogation of cocaine- and Tat-mediated synergistic increase in cell proliferation on inhibition of both ligand-dependent and ROS/Src-mediated ligand-independent phosphorylation of PDGFRβ.
authors.affiliation: Departments of 1 Internal Medicine and.
authors.forename: Pranjali N
authors.initials: PN
authors.lastname: Dalvi
authors.affiliation: 2 Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Vijayalaxmi G
authors.initials: VG
authors.lastname: Gupta
authors.affiliation: Departments of 1 Internal Medicine and.
authors.forename: Brooke R
authors.initials: BR
authors.lastname: Griffin
authors.affiliation: Departments of 1 Internal Medicine and.
authors.forename: Amy
authors.initials: A
authors.lastname: O'Brien-Ladner
authors.affiliation: Departments of 1 Internal Medicine and.|2 Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Navneet K
authors.initials: NK
authors.lastname: Dhillon
mesh_terms: D049109:Cell Proliferation; D002478:Cells, Cultured; D003042:Cocaine / Q000494:pharmacology*; D015658:HIV Infections / Q000150:complications / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia / Q000139:chemically induced / Q000821:virology; D006976:Hypertension, Pulmonary / Q000821:virology; D013287:Illicit Drugs / Q000494:pharmacology*; D008024:Ligands; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000473:pathology*; D018384:Oxidative Stress; D011651:Pulmonary Artery / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000502:physiology*
chemical_list: D013287:Illicit Drugs; D008024:Ligands; D017382:Reactive Oxygen Species; D054322:tat Gene Products, Human Immunodeficiency Virus; D020797:Receptor, Platelet-Derived Growth Factor beta; D019061:src-Family Kinases; D003042:Cocaine
keywords: cocaine; platelet-derived growth factor receptor; pulmonary arterial hypertension; reactive oxygen species; transactivator of transcription