RESUMO
OBJECTIVE: To investigate the role of bone morphogenetic proteins (BMPs) on α-B-crystallin (CRYAB) expression and its physiological consequences on endothelial cells (ECs). APPROACH AND RESULTS: We report that the gene encoding for the small heat shock protein, CRYAB, is a transcriptional target of the BMP signaling pathway. We demonstrate that CRYAB expression is upregulated strongly by BMPs in an EC line and in human lung microvascular ECs and human umbilical vein ECs. We show that BMP signals through the BMPR2-ALK1 pathway to upregulate CRYAB expression through a transcriptional indirect mechanism involving Id1. We observed that the known antiapoptotic effect of the BMPs is, in part, because of the upregulation of CRYAB expression in EC. We also show that cryab is downregulated in vivo, in a mouse model of pulmonary arterial hypertension induced by chronic hypoxia where the BMP pathway is downregulated. CONCLUSIONS: We demonstrate a cross-talk between BMPs and CRYAB and a major effect of this regulatory interaction on resistance to apoptosis.
Assuntos
Apoptose/fisiologia , Proteínas Morfogenéticas Ósseas/metabolismo , Células Endoteliais/metabolismo , Hipertensão Pulmonar/metabolismo , Pulmão/irrigação sanguínea , Cadeia B de alfa-Cristalina/metabolismo , Receptores de Activinas Tipo II/metabolismo , Animais , Apoptose/efeitos dos fármacos , Proteína Morfogenética Óssea 4/metabolismo , Proteína Morfogenética Óssea 4/farmacologia , Proteína Morfogenética Óssea 7/metabolismo , Proteína Morfogenética Óssea 7/farmacologia , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/metabolismo , Proteínas Morfogenéticas Ósseas/farmacologia , Modelos Animais de Doenças , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Hipertensão Pulmonar Primária Familiar , Fator 2 de Diferenciação de Crescimento , Fatores de Diferenciação de Crescimento/metabolismo , Fatores de Diferenciação de Crescimento/farmacologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Hipertensão Pulmonar/patologia , Camundongos , RNA Interferente Pequeno/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologia , Cadeia B de alfa-Cristalina/genéticaRESUMO
The transforming growth factor-ß/bone morphogenic protein (BMP) system is a major pathway for angiogenesis and is involved in hereditary vascular diseases. Here we report that the gene encoding the vasoactive and vascular cell growth-regulating peptide apelin is a target of the BMP pathway. We demonstrate that apelin expression is strongly downregulated by BMP in an endothelial cell line as well as in lung endothelial microvascular cells. We show that BMP signals through the BMPR2-SMAD pathway to downregulate apelin expression and that a transcriptional direct and indirect mechanism is required. The BMP-induced downregulation of apelin expression was found to be critical for hypoxia-induced growth of endothelial cells, because the growth inhibitory effect of BMP in this condition is suppressed by enforced expression of apelin. Thus, we describe an important link between a signaling pathway involved in angiogenesis and vascular diseases and a peptide regulating vascular homeostasis.
Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Células Endoteliais/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Transdução de Sinais/fisiologia , Transdução de Sinais/efeitos da radiação , Apelina , Proteína Morfogenética Óssea 4/metabolismo , Proteína Morfogenética Óssea 4/farmacologia , Proteína Morfogenética Óssea 7/metabolismo , Proteína Morfogenética Óssea 7/farmacologia , Proteínas Morfogenéticas Ósseas/farmacologia , Linhagem Celular , Regulação da Expressão Gênica/efeitos dos fármacos , Fator 2 de Diferenciação de Crescimento , Fatores de Diferenciação de Crescimento/metabolismo , Fatores de Diferenciação de Crescimento/farmacologia , Humanos , Hipóxia/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Microvasos/efeitos dos fármacos , Microvasos/metabolismo , Neovascularização Patológica/induzido quimicamente , Neovascularização Patológica/metabolismo , Proteínas Smad/metabolismoRESUMO
Apelin has been identified as the endogenous ligand of the human orphan G protein-coupled receptor APJ. This peptide exerts a variety of cardiovascular effects and particularly acts as an activator of angiogenesis. Importantly, hypoxia has been reported to regulate apelin expression but the molecular mechanism underlying hypoxia-induced apelin expression and the relationship with the physiological response of the apelin/APJ system are still not established. Here, we demonstrate that apelin expression is induced by hypoxia in cultured endothelial and vascular smooth muscle cells as well as in lung from mice exposed to acute hypoxia. Transient transfection experiments show that hypoxia-inducible transcriptional activation of apelin requires an intact hypoxia-responsive element (+813/+826) located within the first intron of the human apelin gene. Chromatin immunoprecipitation assay reveals that hypoxia-inducible factor-1alpha binds to the endogenous hypoxia-responsive element site of the apelin gene. Moreover, overexpression of hypoxia-inducible factor-1alpha increases the transcriptional activity of a reporter construct containing this hypoxia-responsive element, whereas small interfering RNA-mediated hypoxia-inducible factor-1alpha knockdown abolishes hypoxia-induced apelin expression. Finally, microinterfering RNA-mediated apelin or APJ receptor knockdown inhibits both hypoxia-induced endothelial cell proliferation in vitro and hypoxia-induced vessel regeneration in the caudal fin regeneration of Fli-1 transgenic zebrafish. The hypoxia-induced apelin expression may, thus, provide a new mechanism involved in adaptive physiological and pathophysiological response of vascular cells to low oxygen level.
