title: Activation of GATA-4 by serotonin in pulmonary artery smooth muscle cells.
abstract: Serotonin (5-hydroxytryptamine (5-HT)) is a mitogen of pulmonary artery smooth muscle cells (PASMC) and plays an important role in the development of pulmonary hypertension. Signal transduction initiated by 5-HT involves serotonin transporter-dependent generation of reactive oxygen species and activation of the MEK-ERK pathway. However, the downstream transcriptional regulatory components have not been identified. In systemic smooth muscle cells, GATA-6 has been shown to regulate mitogenesis by driving cells into a quiescent state, and the down-regulation of GATA-6 induces mitogenesis. Thus, the present study tested the hypothesis that 5-HT induces mitogenesis of PASMC by down-regulating GATA-6. Quiescent bovine PASMC were treated with 5-HT, and the binding activity of nuclear extracts toward GATA DNA sequence was monitored. Surprisingly, PASMC express GATA-4, and 5-HT up-regulates the GATA DNA binding activity. Pretreatment of cells with inhibitors of serotonin transporter, reactive oxygen species, and MEK blocks GATA-4 activation by 5-HT. GATA-4 is not activated when the ERK phosphorylation site is mutated, indicating that 5-HT phosphorylates GATA-4 via the MEK/ERK pathway. GATA up-regulation is also induced by other mitogens of PASMC such as endothelin-1 and platelet-derived growth factor. Dominant negative mutants of GATA-4 suppress cyclin D2 expression and cell growth, indicating that GATA-4 activation regulates PASMC proliferation. Thus, GATA-4 mediates 5-HT-induced growth of PASMC and may be an important therapeutic target for the prevention of pulmonary hypertension.
authors.affiliation: Department of Medicine, Tufts University, Boston, Massachusetts 02111, USA. yuichiro.suzuki@tufts.edu
authors.forename: Yuichiro J
authors.initials: YJ
authors.lastname: Suzuki
authors.forename: Regina M
authors.initials: RM
authors.lastname: Day
authors.forename: Chia Chi
authors.initials: CC
authors.lastname: Tan
authors.forename: Tor H
authors.initials: TH
authors.lastname: Sandven
authors.forename: Qiangrong
authors.initials: Q
authors.lastname: Liang
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Molkentin
authors.forename: Barry L
authors.initials: BL
authors.lastname: Fanburg
mesh_terms: D000818:Animals; D002417:Cattle; D004268:DNA-Binding Proteins / Q000502:physiology*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D050991:GATA4 Transcription Factor; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011651:Pulmonary Artery / Q000166:cytology / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D016166:Free Radical Scavengers; D050991:GATA4 Transcription Factor; D014157:Transcription Factors; D012701:Serotonin; D017346:Protein Serine-Threonine Kinases