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Critical function for the Ras-GTPase activating protein RASA3 in vertebrate erythropoiesis and megakaryopoiesis
Lionel Blanc, Steven L. Ciciotte, Babette Gwynn, Gordon J. Hildick-Smith, Eric L. Pierce, Kathleen A. Soltis, Jeffrey D. Cooney, Barry H. Paw and Luanne L. Peters
Proceedings of the National Academy of Sciences of the United States of America
Vol. 109, No. 30 (July 24, 2012), pp. 12099-12104
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/41684893
Page Count: 6
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Phenotype-driven approaches to gene discovery using inbred mice have been instrumental in identifying genetic determinants of inherited blood dyscrasias. The recessive mutant scat (severe combined anemia and thrombocytopenia) alternates between crisis and remission episodes, indicating an aberrant regulatory feedback mechanism common to erythrocyte and platelet formation. Here, we identify a missense mutation (G125V) in the scat Rasa3 gene, encoding a Ras GTPase activating protein (RasGAP), and elucidate the mechanism producing crisis episodes. The mutation causes mislocalization of RASA3 to the cytosol in scat red cells where it is inactive, leading to increased GTP-bound Ras. Erythropoiesis is severely blocked in scat crisis mice, and ~94% succumb during the second crisis (~30 d of age) from catastrophic hematopoietic failure in the spleen and bone marrow. Megakaryopoiesis is also defective during crisis. Notably, the scat phenotype is recapitulated in zebrafish when rasa3 is silenced. These results highlight a critical, conserved, and nonredundant role for RASA3 in vertebrate hematopoiesis.
Proceedings of the National Academy of Sciences of the United States of America © 2012 National Academy of Sciences