Endothelial RAF1/ERK activation regulates arterial morphogenesis

• Published in: Blood 2013-05, Vol.121 (19), p.3988-3996
• Main Authors: Deng, Yong, Larrivée, Bruno, Zhuang, Zhen W., Atri, Deepak, Moraes, Filipa, Prahst, Claudia, Eichmann, Anne, Simons, Michael
• Format: Article
• Language: English
• Subjects: Animals; Arteries - embryology; Arteries - metabolism; Cells, Cultured; Embryo, Mammalian; Endothelial Cells - metabolism; Enzyme Activation - genetics; Enzyme Activation - physiology; Extracellular Signal-Regulated MAP Kinases - metabolism; Extracellular Signal-Regulated MAP Kinases - physiology; Female; Gene Expression Regulation, Developmental; Human Umbilical Vein Endothelial Cells - enzymology; Human Umbilical Vein Endothelial Cells - metabolism; Humans; Male; Mice; Morphogenesis - genetics; Morphogenesis - physiology; Pregnancy; Proto-Oncogene Proteins c-raf - genetics; Proto-Oncogene Proteins c-raf - metabolism; Proto-Oncogene Proteins c-raf - physiology; Semaphorins - genetics; Vascular Biology
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2012-12-474601

Arterial morphogenesis is one of the most critical events during embryonic vascular development. Although arterial fate specification is mainly controlled by the Notch signaling pathway, arterial-venous patterning is modulated by a number of guidance factors. How these pathways are regulated is still largely unknown. Here, we demonstrate that endothelial activation of RAF1/extracellular signal-regulated kinase (ERK) pathway regulates arterial morphogenesis and arterial-venous patterning via Δ/Notch and semaphorin signaling. Introduction of a single amino acid RAF1 mutant (RAF1 Ser259Ala), which renders it resistant to inhibition by phosphorylation, into endothelial cells in vitro induced expression of virtually the entire embryonic arteriogenic program and activated semaphorin 6A–dependent endothelial cell–cell repulsion. In vivo, endothelial-specific expression of RAF1S259A during development induced extensive arterial morphogenesis both in the yolk sac and the embryo proper and disrupted arterial-venous patterning. Our results suggest that endothelial ERK signaling is critical for both arteriogenesis and arterial-venous patterning and that RAF1 Ser259 phosphorylation plays a critical role in preventing unopposed ERK activation. •RAF1 Ser259 phosphorylation is a critical regulator step controlling arterial morphogenesis and arterial-venous patterning.•ERK activation controls DLL4/Notch signaling and semaphorin 6A–mediated endothelial cell repulsion.