Molecular characterization and pharmacological suppression of pulmonary arterial hypertension

• Applicants: Dr. Ruth Olmer; Professor Dr. Salim Seyfried
• Subject Area: Cardiology, Angiology ; Cell Biology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455781064

Pulmonary arterial hypertension (PAH) is a severe clinical condition that has been associated, among others, with variants of the BMP type II receptor (BMPR-II or BMPR2). Currently, we lack a solid understanding of the disease-relevant molecular pathways downstream of BMPR2, which would come to benefit effective pharmacological therapies for the treatment of this life-threatening condition. We also lack a good understanding of whether mutated endothelial cells (EC)s are the primary driver of PAH or whether the mutations impact vascular smooth muscle cell (vSMC) biology directly. A particular challenge is to perform such studies as well as drug suppression screens in the context of the complex multi-tissue comprising vertebrate cardiovascular system. Our proposal is based on the hypothesis that functional loss of the PAH-associated genes BMPR2, ACVRL1/ALK1, ENDOGLIN, or VEGFR3/FLT4 alters biomechanical signalling within ECs and that this affects the homeostatic regulation of blood pressure. To address this hypothesis, S. Seyfried will develop zebrafish embryonic PAH-disease models to further investigate the molecular pathways affected by alterations in BMPR2 signalling. He will also characterize the molecular similarities of these mutants with other PAH-disease models based on acvrl1, endoglin, or flt4 mutants. In a complementary approach, R. Olmer will generate human induced pluripotent stem cell lines (hiPSC) either from PAH patients or by introducing defined PAH relevant mutations in control hiPSC lines which will be subsequently differentiated towards ECs as well as vSMCs. These cell lines will be characterized using molecular and cell biological tools. While S. Seyfried will perform an unbiased small molecule suppression screen using FDA-approved substances in the zebrafish to identify molecular pathways relevant to PAH, R. Olmer will conduct a similar screen on mutated human iPSC-derived ECs carrying PAH specific mutations. Our proposal joins the genetic power of analyzing the transparent vasculature in zebrafish PAH models with assessing the disease-relevance of findings in patient-derived iPSC-derived ECs and vSMCs. Genetic and pharmacological manipulations in these models will provide important novel insights into the etiology of this devastating disease and towards therapeutic approaches.

• DFG Programme: Research Grants