Prmt5 promotes vascular morphogenesis in zebrafish independently of its methyltransferase activity.

In vertebrate, blood cell formation is tightly associated with the development of the vascular system. While the transcriptional cascade underlying blood vessel formation starts to be better characterized, little is known concerning the role and mode of action of epigenetic enzymes during this process. Here, we explored the role of the Protein Arginine Methyl Transferase Prmt5 during blood vessel formation and in hematopoiesis in zebrafish. Through the generation of a Prmt5 mutant, we highlight a key role of Prmt5 in both hematopoiesis and blood vessel formation. Prmt5 promotes vascular morphogenesis through the transcriptional control of ETS transcription factor and adhesion proteins in endothelial cells. Moreover, we show that the methyltransferase activity of Prmt5 was not required to regulate gene expression, and comparison of chromatin architecture impact on reporter genes expression lead us to propose a role of scaffold protein for Prmt5 to facilitate chromatin looping formation in these cells.