Activation of GATA-4 by Serotonin in Pulmonary Artery Smooth Muscle Cells

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. 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. 5-hydroxytryptamine mitogen-activated protein kinase/extracellular signal-regulated kinase kinase extracellular signal-regulated kinase serotonin transporter pulmonary artery smooth muscle cells reactive oxygen species endothelin-1 platelet-derived growth factor Electrophoretic mobility shift assay Exposure to chronic hypoxia leads to the development of pulmonary hypertension through persistent vasoconstriction as well as structural remodeling of pulmonary vessels. Proliferation of smooth muscle cells is an important component of pulmonary vascular remodeling that results in increased medial muscular wall thickness. Among a number of mediators of pulmonary hypertension, serotonin (5-hydroxytryptamine (5-HT)1) appears to play an important role in the remodeling of the pulmonary circulation (1Lee S.L. Wang W.W. Fanburg B.L. Circ. Res. 1991; 68: 1362-1368Crossref PubMed Scopus (140) Google Scholar, 2Eddahibi S. Raffestin B. Pham I. Launay J.M. Aegerter P. Sitbon M. Adnot S. Am. J. Physiol. 1997; 272: H1173-H1181PubMed Google Scholar, 3Eddahibi S. Hanoun N. Lanfumey L. Lesch K.P. Raffestin B. Hamon M. Adnot S. J. Clin. Invest. 2000; 105: 1555-1562Crossref PubMed Scopus (272) Google Scholar).Evidence for the role of 5-HT in the development of pulmonary hypertension was first recognized in fawn-hooded rats, in which a genetic deficit in 5-HT platelet storage and high plasma levels of 5-HT are associated with a susceptibility to developing pulmonary hypertension in response to mild hypoxia (4Sato K. Webb S. Tucker A. Rabinovitch M. Obrien R.F. McMurtry I.F. Stelzne T.J. Am. Rev. Respir. Dis. 1992; 145: 793-797Crossref PubMed Google Scholar). A further study showed that a continuous intravenous infusion of 5-HT during a 2-week exposure of rats to hypoxia potentiated the development of pulmonary hypertension (2Eddahibi S. Raffestin B. Pham I. Launay J.M. Aegerter P. Sitbon M. Adnot S. Am. J. Physiol. 1997; 272: H1173-H1181PubMed Google Scholar). The role of 5-HT in pulmonary hypertension appears to be through the serotonin transporter (SERT), as mice deficient for SERT developed less hypoxic pulmonary hypertension and vascular remodeling than did control animals exposed to the same conditions (3Eddahibi S. Hanoun N. Lanfumey L. Lesch K.P. Raffestin B. Hamon M. Adnot S. J. Clin. Invest. 2000; 105: 1555-1562Crossref PubMed Scopus (272) Google Scholar).High levels of plasma 5-HT have been observed in humans in association with primary pulmonary hypertension (5Herve P. Drouet L. Dosquet C. Launay J.M. Rain B. Simonneau L. Caen J. Duroux P. Am. J. Med. 1990; 89: 117-120Abstract Full Text PDF PubMed Scopus (146) Google Scholar, 6Herve P. Launay J.M. Scrobohaci M.L. Brenot F. Simonneau G. Petitpretz P. Poubeau P. Cerrina J. Duroux P. Drouet L. Am. J. Med. 1995; 99: 249-254Abstract Full Text PDF PubMed Scopus (469) Google Scholar). More recently, Eddahibiet al. (7Eddahibi S. Humbert M. Fadel E. Raffestin B. Darmon M. Capron F. Simonneau G. Dartevelle P. Hamon M. Adnot S. J. Clin. Invest. 2001; 198: 1141-1150Crossref Scopus (488) Google Scholar) report that pulmonary artery smooth muscle cells (PASMC) from patients with primary pulmonary hypertension grow faster than the cells from control subjects due to increased expression of SERT. The importance of 5-HT in human pulmonary hypertension is supported by clinical observations that pulmonary hypertension is associated with the use of amphetamine-like appetite suppressants, fenfluramine, dexfenfluramine, and aminorex (8Abenhaim L. Moride Y. Brenot F. Rich S. Benichou J. Kurz X. Higenbottam T. Oakley C. Wounters E. Aubier M. Simonneau G. Begaud B. N. Engl. J. Med. 1996; 335: 609-616Crossref PubMed Scopus (1069) Google Scholar). The mechanism of these appetite suppressants on PASMC may involve both direct interactions with SERT and a stimulation of SERT expression (9Rothman R.B. Ayestas M.A. Dersch C.M. Baumann M.H. Circulation. 1999; 100: 869-875Crossref PubMed Scopus (183) Google Scholar, 10Lee S.L. Wang W.W. Fanburg B.L. FASEB J. 2001; 15: 1324-1325Crossref PubMed Scopus (28) Google Scholar, 11Eddahibi S. Adnot S. Respir. Res. 2002; 3: 9-12Crossref PubMed Scopus (60) Google Scholar).5-HT can mediate cell signaling by interacting with several subtypes of 5-HT receptors or through SERT, which transports 5-HT across the membrane using a Na+/Cl− gradient. In bovine PASMC, only one 5-HT receptor has been identified, which resembles the 5-HT1A or 5-HT4 receptor (12Lee S.L. Fanburg B.L. J. Cell. Physiol. 1992; 150: 396-405Crossref PubMed Scopus (13) Google Scholar, 13Becker B.N. Gettys T.W. Middleton J.P. Olsen C.L. Albers F.J. Lee S.L. Fanburg B.L. Raymond J.R. Mol. Pharmacol. 1992; 42: 817-825PubMed Google Scholar). However, mitogenic and hypertrophic responses by 5-HT are believed to be due to the action of SERT (14Lee S.L. Wang W.W. Lanzillo J.J. Fanburg B.L. Am. J. Physiol. 1994; 266: L46-L52Crossref PubMed Google Scholar). The mechanism of 5-HT signaling for PASMC growth through SERT has been shown to involve tyrosine phosphorylation of GTPase-activating protein (15Lee S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1997; 272: C223-C230Crossref PubMed Google Scholar) and the production of reactive oxygen species (ROS) such as superoxide (16Lee S.L. Wang W.W. Fanburg B.L. Free Radic. Biol. Med. 1998; 24: 855-858Crossref PubMed Scopus Google Scholar) and S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 2001; Google via the activation of signaling to the MEK-ERK as the 5-HT-induced PASMC growth S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1999; PubMed Google Scholar). However, downstream signaling which are activated by ERK for the of cell growth, have not been GATA of with a DNA binding that with DNA regulatory The are for cell development 1995; PubMed Scopus Google the are in cells of the and J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). In smooth muscle cells, GATA-6 has been shown to play a role in cells in a quiescent state, and mitogens GATA-6 to of cells E. T. J. L. J.R. K. 1996; PubMed Scopus Google Scholar). The mechanism appears to involve the of GATA-6 was to into by kinase E. M. K. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). of GATA-6 down-regulation in rats in the artery T. S.L. T. K. Circ. Res. 1999; PubMed Scopus Google present tested the hypothesis that 5-HT may GATA-6 in Surprisingly, results that PASMC express GATA-4 that is activated by 5-HT and PASMC plays an important role in the development of pulmonary hypertension, in due to to PASMC growth (1Lee S.L. Wang W.W. Fanburg B.L. Circ. Res. 1991; 68: 1362-1368Crossref PubMed Scopus (140) Google Scholar). The 5-HT signaling has been to involve 5-HT through SERT, tyrosine phosphorylation of GTPase-activating which may in and in production of and the activation of MEK and ERK (14Lee S.L. Wang W.W. Lanzillo J.J. Fanburg B.L. Am. J. Physiol. 1994; 266: L46-L52Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1997; 272: C223-C230Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Free Radic. Biol. Med. 1998; 24: 855-858Crossref PubMed Scopus Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 2001; Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1999; PubMed Google Scholar). is factor activation by 5-HT. In muscle 5-HT has been shown to receptor to the and of I. J. J. Biol. 1997; 272: Full Text Full Text PDF PubMed Scopus Google and in cells an site E. J.J. Mol. Cell. 2000; PubMed Scopus Google Scholar). in smooth muscle an site J.M. L. J.J. Mol. Cell. 1999; PubMed Scopus Google Scholar). In the present the mechanism by and for smooth muscle cell which involves the down-regulation of GATA-6 E. T. J. L. J.R. K. 1996; PubMed Scopus Google E. M. K. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, that 5-HT GATA-6 in Surprisingly, that 5-HT increased the GATA DNA binding activity in PASMC and that these cells also express GATA-4 factor that is by 5-HT Thus, GATA may in systemic and pulmonary smooth muscle cell have been in transcriptional regulatory and of GATA-4 has been shown to these A number of that have been shown to be during such as and factor GATA regulatory in J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, GATA-4 has been to regulate muscle cell GATA-4 can be activated by a transduction and J.R. C.L. B. J. J. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). More recently, GATA-4 has shown also to be via the MEK/ERK in response to K. J. J. 2001; PubMed Scopus Google Scholar) or T. K. S. T. T. S. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar) in the ERK phosphorylation was to be in response to Mol. Cell. Biol. 2001; PubMed Scopus Google Scholar). with these activation of GATA-4 in PASMC phosphorylation of MEK inhibitors 5-HT-induced GATA and the of the ERK phosphorylation site with the for GATA-4 in PASMC, not a role of GATA-6 in mitogenesis as in other vascular E. T. J. L. J.R. K. 1996; PubMed Scopus Google of GATA-4 activation by 5-HT may the of PASMC proliferation. GATA have been in of cell such as cyclin D2 Mol. Cell. 1997; Scholar) and cyclin P. Y. K. 1996; PubMed Scopus Google Scholar). al. I. K. J. K. T. M. T. Y. 2000; PubMed Google Scholar) report that induced the expression of cyclin in a cell has also been shown to regulate the of and cells S. T. N. K. S. T. T. M. 1998; PubMed Google Scholar). and 1997; 89: PubMed Google Scholar) report that is for the of from the present study that the of GATA-4 activity by a negative the cell number and the expression of cyclin D2 that GATA-4 regulates mitogenesis of other mitogens of PASMC such as and also GATA DNA binding that GATA-4 may be a of PASMC role of GATA-4 activation is to regulate cell and In GATA-4 was as a cell and down-regulation of factor in the of Y. K. T. Y. T. Mol. Pharmacol. PubMed Scopus Google K. Y. I. T. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). that 5-HT of PASMC Fanburg B.L. Am. J. Respir. Med. in Scopus Google the present study that PASMC express GATA-4 that is activated by 5-HT. the have the 5-HT transduction for GATA-4 activation appears to involve the SERT, MEK/ERK and the phosphorylation of the ERK phosphorylation site the GATA-4 of negative GATA-4 mutants that GATA-4 regulates the expression of cyclin D2 and PASMC results that GATA-4 may play a role in 5-HT-induced PASMC growth and that of may in the development of pulmonary hypertension. Thus, therapeutic GATA-4 may be pulmonary hypertension. Exposure to chronic hypoxia leads to the development of pulmonary hypertension through persistent vasoconstriction as well as structural remodeling of pulmonary vessels. Proliferation of smooth muscle cells is an important component of pulmonary vascular remodeling that results in increased medial muscular wall thickness. Among a number of mediators of pulmonary hypertension, serotonin (5-hydroxytryptamine (5-HT)1) appears to play an important role in the remodeling of the pulmonary circulation (1Lee S.L. Wang W.W. Fanburg B.L. Circ. Res. 1991; 68: 1362-1368Crossref PubMed Scopus (140) Google Scholar, 2Eddahibi S. Raffestin B. Pham I. Launay J.M. Aegerter P. Sitbon M. Adnot S. Am. J. Physiol. 1997; 272: H1173-H1181PubMed Google Scholar, 3Eddahibi S. Hanoun N. Lanfumey L. Lesch K.P. Raffestin B. Hamon M. Adnot S. J. Clin. Invest. 2000; 105: 1555-1562Crossref PubMed Scopus (272) Google Scholar). for the role of 5-HT in the development of pulmonary hypertension was first recognized in fawn-hooded rats, in which a genetic deficit in 5-HT platelet storage and high plasma levels of 5-HT are associated with a susceptibility to developing pulmonary hypertension in response to mild hypoxia (4Sato K. Webb S. Tucker A. Rabinovitch M. Obrien R.F. McMurtry I.F. Stelzne T.J. Am. Rev. Respir. Dis. 1992; 145: 793-797Crossref PubMed Google Scholar). A further study showed that a continuous intravenous infusion of 5-HT during a 2-week exposure of rats to hypoxia potentiated the development of pulmonary hypertension (2Eddahibi S. Raffestin B. Pham I. Launay J.M. Aegerter P. Sitbon M. Adnot S. Am. J. Physiol. 1997; 272: H1173-H1181PubMed Google Scholar). The role of 5-HT in pulmonary hypertension appears to be through the serotonin transporter (SERT), as mice deficient for SERT developed less hypoxic pulmonary hypertension and vascular remodeling than did control animals exposed to the same conditions (3Eddahibi S. Hanoun N. Lanfumey L. Lesch K.P. Raffestin B. Hamon M. Adnot S. J. Clin. Invest. 2000; 105: 1555-1562Crossref PubMed Scopus (272) Google Scholar). levels of plasma 5-HT have been observed in humans in association with primary pulmonary hypertension (5Herve P. Drouet L. Dosquet C. Launay J.M. Rain B. Simonneau L. Caen J. Duroux P. Am. J. Med. 1990; 89: 117-120Abstract Full Text PDF PubMed Scopus (146) Google Scholar, 6Herve P. Launay J.M. Scrobohaci M.L. Brenot F. Simonneau G. Petitpretz P. Poubeau P. Cerrina J. Duroux P. Drouet L. Am. J. Med. 1995; 99: 249-254Abstract Full Text PDF PubMed Scopus (469) Google Scholar). More recently, Eddahibiet al. (7Eddahibi S. Humbert M. Fadel E. Raffestin B. Darmon M. Capron F. Simonneau G. Dartevelle P. Hamon M. Adnot S. J. Clin. Invest. 2001; 198: 1141-1150Crossref Scopus (488) Google Scholar) report that pulmonary artery smooth muscle cells (PASMC) from patients with primary pulmonary hypertension grow faster than the cells from control subjects due to increased expression of SERT. The importance of 5-HT in human pulmonary hypertension is supported by clinical observations that pulmonary hypertension is associated with the use of amphetamine-like appetite suppressants, fenfluramine, dexfenfluramine, and aminorex (8Abenhaim L. Moride Y. Brenot F. Rich S. Benichou J. Kurz X. Higenbottam T. Oakley C. Wounters E. Aubier M. Simonneau G. Begaud B. N. Engl. J. Med. 1996; 335: 609-616Crossref PubMed Scopus (1069) Google Scholar). The mechanism of these appetite suppressants on PASMC may involve both direct interactions with SERT and a stimulation of SERT expression (9Rothman R.B. Ayestas M.A. Dersch C.M. Baumann M.H. Circulation. 1999; 100: 869-875Crossref PubMed Scopus (183) Google Scholar, 10Lee S.L. Wang W.W. Fanburg B.L. FASEB J. 2001; 15: 1324-1325Crossref PubMed Scopus (28) Google Scholar, 11Eddahibi S. Adnot S. Respir. Res. 2002; 3: 9-12Crossref PubMed Scopus (60) Google Scholar). 5-HT can mediate cell signaling by interacting with several subtypes of 5-HT receptors or through SERT, which transports 5-HT across the membrane using a Na+/Cl− gradient. In bovine PASMC, only one 5-HT receptor has been identified, which resembles the 5-HT1A or 5-HT4 receptor (12Lee S.L. Fanburg B.L. J. Cell. Physiol. 1992; 150: 396-405Crossref PubMed Scopus (13) Google Scholar, 13Becker B.N. Gettys T.W. Middleton J.P. Olsen C.L. Albers F.J. Lee S.L. Fanburg B.L. Raymond J.R. Mol. Pharmacol. 1992; 42: 817-825PubMed Google Scholar). However, mitogenic and hypertrophic responses by 5-HT are believed to be due to the action of SERT (14Lee S.L. Wang W.W. Lanzillo J.J. Fanburg B.L. Am. J. Physiol. 1994; 266: L46-L52Crossref PubMed Google Scholar). The mechanism of 5-HT signaling for PASMC growth through SERT has been shown to involve tyrosine phosphorylation of GTPase-activating protein (15Lee S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1997; 272: C223-C230Crossref PubMed Google Scholar) and the production of reactive oxygen species (ROS) such as superoxide (16Lee S.L. Wang W.W. Fanburg B.L. Free Radic. Biol. Med. 1998; 24: 855-858Crossref PubMed Scopus Google Scholar) and S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 2001; Google via the activation of signaling to the MEK-ERK as the 5-HT-induced PASMC growth S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1999; PubMed Google Scholar). However, downstream signaling which are activated by ERK for the of cell growth, have not been identified. The GATA of with a DNA binding that with DNA regulatory The are for cell development 1995; PubMed Scopus Google the are in cells of the and J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). In smooth muscle cells, GATA-6 has been shown to play a role in cells in a quiescent state, and mitogens GATA-6 to of cells E. T. J. L. J.R. K. 1996; PubMed Scopus Google Scholar). The mechanism appears to involve the of GATA-6 was to into by kinase E. M. K. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). of GATA-6 down-regulation in rats in the artery T. S.L. T. K. Circ. Res. 1999; PubMed Scopus Google Scholar). The present tested the hypothesis that 5-HT may GATA-6 in Surprisingly, results that PASMC express GATA-4 that is activated by 5-HT and PASMC plays an important role in the development of pulmonary hypertension, in due to to PASMC growth (1Lee S.L. Wang W.W. Fanburg B.L. Circ. Res. 1991; 68: 1362-1368Crossref PubMed Scopus (140) Google Scholar). The 5-HT signaling has been to involve 5-HT through SERT, tyrosine phosphorylation of GTPase-activating which may in and in production of and the activation of MEK and ERK (14Lee S.L. Wang W.W. Lanzillo J.J. Fanburg B.L. Am. J. Physiol. 1994; 266: L46-L52Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1997; 272: C223-C230Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Free Radic. Biol. Med. 1998; 24: 855-858Crossref PubMed Scopus Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 2001; Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1999; PubMed Google Scholar). is factor activation by 5-HT. In muscle 5-HT has been shown to receptor to the and of I. J. J. Biol. 1997; 272: Full Text Full Text PDF PubMed Scopus Google and in cells an site E. J.J. Mol. Cell. 2000; PubMed Scopus Google Scholar). in smooth muscle an site J.M. L. J.J. Mol. Cell. 1999; PubMed Scopus Google Scholar). In the present the mechanism by and for smooth muscle cell which involves the down-regulation of GATA-6 E. T. J. L. J.R. K. 1996; PubMed Scopus Google E. M. K. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, that 5-HT GATA-6 in Surprisingly, that 5-HT increased the GATA DNA binding activity in PASMC and that these cells also express GATA-4 factor that is by 5-HT Thus, GATA may in systemic and pulmonary smooth muscle cell have been in transcriptional regulatory and of GATA-4 has been shown to these A number of that have been shown to be during such as and factor GATA regulatory in J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, GATA-4 has been to regulate muscle cell GATA-4 can be activated by a transduction and J.R. C.L. B. J. J. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). More recently, GATA-4 has shown also to be via the MEK/ERK in response to K. J. J. 2001; PubMed Scopus Google Scholar) or T. K. S. T. T. S. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar) in the ERK phosphorylation was to be in response to Mol. Cell. Biol. 2001; PubMed Scopus Google Scholar). with these activation of GATA-4 in PASMC phosphorylation of MEK inhibitors 5-HT-induced GATA and the of the ERK phosphorylation site with the for GATA-4 in PASMC, not a role of GATA-6 in mitogenesis as in other vascular E. T. J. L. J.R. K. 1996; PubMed Scopus Google of GATA-4 activation by 5-HT may the of PASMC proliferation. GATA have been in of cell such as cyclin D2 Mol. Cell. 1997; Scholar) and cyclin P. Y. K. 1996; PubMed Scopus Google Scholar). al. I. K. J. K. T. M. T. Y. 2000; PubMed Google Scholar) report that induced the expression of cyclin in a cell has also been shown to regulate the of and cells S. T. N. K. S. T. T. M. 1998; PubMed Google Scholar). and 1997; 89: PubMed Google Scholar) report that is for the of from the present study that the of GATA-4 activity by a negative the cell number and the expression of cyclin D2 that GATA-4 regulates mitogenesis of other mitogens of PASMC such as and also GATA DNA binding that GATA-4 may be a of PASMC role of GATA-4 activation is to regulate cell and In GATA-4 was as a cell and down-regulation of factor in the of Y. K. T. Y. T. Mol. Pharmacol. PubMed Scopus Google K. Y. I. T. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). that 5-HT of PASMC Fanburg B.L. Am. J. Respir. Med. in Scopus Google the present study that PASMC express GATA-4 that is activated by 5-HT. the have the 5-HT transduction for GATA-4 activation appears to involve the SERT, MEK/ERK and the phosphorylation of the ERK phosphorylation site the GATA-4 of negative GATA-4 mutants that GATA-4 regulates the expression of cyclin D2 and PASMC results that GATA-4 may play a role in 5-HT-induced PASMC growth and that of may in the development of pulmonary hypertension. Thus, therapeutic GATA-4 may be pulmonary hypertension. 5-HT plays an important role in the development of pulmonary hypertension, in due to to PASMC growth (1Lee S.L. Wang W.W. Fanburg B.L. Circ. Res. 1991; 68: 1362-1368Crossref PubMed Scopus (140) Google Scholar). The 5-HT signaling has been to involve 5-HT through SERT, tyrosine phosphorylation of GTPase-activating which may in and in production of and the activation of MEK and ERK (14Lee S.L. Wang W.W. Lanzillo J.J. Fanburg B.L. Am. J. Physiol. 1994; 266: L46-L52Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1997; 272: C223-C230Crossref PubMed Google Scholar, S.L. Wang W.W. Fanburg B.L. Free Radic. Biol. Med. 1998; 24: 855-858Crossref PubMed Scopus Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 2001; Google Scholar, S.L. Wang W.W. Fanburg B.L. Am. J. Physiol. 1999; PubMed Google Scholar). is factor activation by 5-HT. In muscle 5-HT has been shown to receptor to the and of I. J. J. Biol. 1997; 272: Full Text Full Text PDF PubMed Scopus Google and in cells an site E. J.J. Mol. Cell. 2000; PubMed Scopus Google Scholar). in smooth muscle an site J.M. L. J.J. Mol. Cell. 1999; PubMed Scopus Google Scholar). In the present the mechanism by and for smooth muscle cell which involves the down-regulation of GATA-6 E. T. J. L. J.R. K. 1996; PubMed Scopus Google E. M. K. J. Biol. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, that 5-HT GATA-6 in Surprisingly, that 5-HT increased the GATA DNA binding activity in PASMC and that these cells also express GATA-4 factor that is by 5-HT Thus, GATA may in systemic and pulmonary smooth muscle cell have been in transcriptional regulatory and of GATA-4 has been shown to these A number of that have been shown to be during such as and factor GATA regulatory in J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, GATA-4 has been to regulate muscle cell GATA-4 can be activated by a transduction and J.R. C.L. B. J. J. Cell. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar). More recently, GATA-4 has shown also to be via the MEK/ERK in response to K. J. J. 2001; PubMed Scopus Google Scholar) or T. K. S. T. T. S. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar) in the ERK phosphorylation was to be in response to Mol. Cell. Biol. 2001; PubMed Scopus Google Scholar). with these activation of GATA-4 in PASMC phosphorylation of MEK inhibitors 5-HT-induced GATA and the of the ERK phosphorylation site with the for GATA-4 in PASMC, not a role of GATA-6 in mitogenesis as in other vascular E. T. J. L. J.R. K. 1996; PubMed Scopus Google Scholar). of GATA-4 activation by 5-HT may the of PASMC proliferation. GATA have been in of cell such as cyclin D2 Mol. Cell. 1997; Scholar) and cyclin P. Y. K. 1996; PubMed Scopus Google Scholar). al. I. K. J. K. T. M. T. Y. 2000; PubMed Google Scholar) report that induced the expression of cyclin in a cell has also been shown to regulate the of and cells S. T. N. K. S. T. T. M. 1998; PubMed Google Scholar). and 1997; 89: PubMed Google Scholar) report that is for the of from the present study that the of GATA-4 activity by a negative the cell number and the expression of cyclin D2 that GATA-4 regulates mitogenesis of other mitogens of PASMC such as and also GATA DNA binding that GATA-4 may be a of PASMC proliferation. role of GATA-4 activation is to regulate cell and In GATA-4 was as a cell and down-regulation of factor in the of Y. K. T. Y. T. Mol. Pharmacol. PubMed Scopus Google K. Y. I. T. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). that 5-HT of PASMC Fanburg B.L. Am. J. Respir. Med. in Scopus Google Scholar). In the present study that PASMC express GATA-4 that is activated by 5-HT. the have the 5-HT transduction for GATA-4 activation appears to involve the SERT, MEK/ERK and the phosphorylation of the ERK phosphorylation site the GATA-4 of negative GATA-4 mutants that GATA-4 regulates the expression of cyclin D2 and PASMC results that GATA-4 may play a role in 5-HT-induced PASMC growth and that of may in the development of pulmonary hypertension. Thus, therapeutic GATA-4 may be pulmonary hypertension. S. Y. and J. for