Abstract 17131: Mir-204 Downregulation Triggers the Activation of Src/stat3/nfat/bmpr2 Axis in Pulmonary Arterial Hypertension.
Introduction: Pulmonary arterial hypertension (PAH) is vascular remodeling disease characterized by enhanced pulmonary artery smooth muscle cells (PASMC) proliferation and suppressed apoptosis. The BMPR-2 downregulation along with the activation of the transcription factor NFAT have been implicated in the maintenance of pro-proliferative and anti-apoptotic stages of cells. Since an increasing number of microRNAs has been implicated in the regulation of specific genes important for cell proliferation and apoptosis, we hypothesized that microRNAs may be associated to these cellular features in the etiology of PAH.
Methods and results: Compare to healthy PASMC and lungs (n=5 to 10 patients), we demonstrated that miR-204 downregulation in human PAH-PASMC and lungs (n=3 to 10 patients) promotes the activation of an Src/STAT3/NFAT axis (immunoblot and immunofluoresence; p<0.05) increasing PAH-PASMC proliferation (PCNA; p<0.05) and resistance to apoptosis (TUNEL; p<0.05). Stimulation experiments for 48hrs with the pro-PAH factors (PDGF, endothelin-1 and Angiotensin II) and time course analysis over 4 weeks in experimental PAH (monocrotaline rats) support that STAT3 activation directly decrease TRPM3 (qRT-PCR) in which miR-204 is encoded (ChIP-PCR) leading to miR-204 downregulation. miR-204 downregulation directly activates the phosphatase SHP2 (luciferase assay), promoting a Src-dependent positive feedback loop sustaining STAT3, downregulating BMPR2 and activating NFAT. More importantly, restoring miR-204 expression significantly (p<0.05) decreases proliferation, resistance to apoptosis in human and experimental PAH model.
Conclusion: Taken together, our study uncovers a new STAT3-miR-204-Src/STAT3/NFAT axis that links the STAT3-dependent BMPR-2 downregulation with the NFAT-mediated pro-proliferative and anti-apoptotic phenotype in PAH and a new potential therapeutic strategy for patients suffering of pulmonary arterial hypertension.
- © 2010 by American Heart Association, Inc.