RASA1 functions in EPHB4 signaling pathway to suppress endothelial mTORC1 activity. J Clin Invest 2014 Jun;124(6):2774-84
Date
05/20/2014Pubmed ID
24837431Pubmed Central ID
PMC4089464DOI
10.1172/JCI67084Scopus ID
2-s2.0-84902180002 (requires institutional sign-in at Scopus site) 76 CitationsAbstract
Vascular malformations are linked to mutations in RAS p21 protein activator 1 (RASA1, also known as p120RasGAP); however, due to the global expression of this gene, it is unclear how these mutations specifically affect the vasculature. Here, we tested the hypothesis that RASA1 performs a critical effector function downstream of the endothelial receptor EPHB4. In zebrafish models, we found that either RASA1 or EPHB4 deficiency induced strikingly similar abnormalities in blood vessel formation and function. Expression of WT EPHB4 receptor or engineered receptors with altered RASA1 binding revealed that the ability of EPHB4 to recruit RASA1 is required to restore blood flow in EPHB4-deficient animals. Analysis of EPHB4-deficient zebrafish tissue lysates revealed that mTORC1 is robustly overactivated, and pharmacological inhibition of mTORC1 in these animals rescued both vessel structure and function. Furthermore, overexpression of mTORC1 in endothelial cells exacerbated vascular phenotypes in animals with reduced EPHB4 or RASA1, suggesting a functional EPHB4/RASA1/mTORC1 signaling axis in endothelial cells. Tissue samples from patients with arteriovenous malformations displayed strong endothelial phospho-S6 staining, indicating increased mTORC1 activity. These results indicate that deregulation of EPHB4/RASA1/mTORC1 signaling in endothelial cells promotes vascular malformation and suggest that mTORC1 inhibitors, many of which are approved for the treatment of certain cancers, should be further explored as a potential strategy to treat patients with vascular malformations.
Author List
Kawasaki J, Aegerter S, Fevurly RD, Mammoto A, Mammoto T, Sahin M, Mably JD, Fishman SJ, Chan JAuthors
Akiko Mammoto MD, PhD Associate Professor in the Pediatrics department at Medical College of WisconsinTadanori Mammoto MD, PhD Associate Professor in the Pediatrics department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AnimalsBlood Vessels
Endothelial Cells
Humans
Mechanistic Target of Rapamycin Complex 1
Multiprotein Complexes
Muscular Dystrophy, Animal
Receptor, EphB4
Signal Transduction
TOR Serine-Threonine Kinases
Zebrafish
Zebrafish Proteins
p120 GTPase Activating Protein
