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Blood, 15 September 2004, Vol. 104, No. 6, pp. 1679-1687. Prepublished online as a Blood First Edition Paper on May 27, 2004; DOI 10.1182/blood-2004-04-1362. This Article Full Text Full Text (PDF) All Versions of this Article: 2004-04-1362v1 104/6/1679    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Zhang, J. Articles by Lodish, H. F. Search for Related Content PubMed PubMed Citation Articles by Zhang, J. Articles by Lodish, H. F. Related Collections Hematopoiesis and Stem Cells Oncogenes and Tumor Suppressors Signal Transduction Free Research Articles Related Article in Blood Online Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  HEMATOPOIESIS Constitutive activation of the MEK/ERK pathway mediates all effects of oncogenic H-ras expression in primary erythroid progenitors Jing Zhang, and Harvey F. Lodish From the Whitehead Institute for Biomedical Research, Cambridge, MA; and the Department of Biology, Massachusetts Institute of Technology, Cambridge, MA. Oncogenic mutations in ras genes frequently occur in patients with myeloid disorders, and in these patients erythropoiesis is often affected. Previously, we showed that expression of oncogenic H-ras in purified mouse primary fetal liver erythroid progenitors blocks terminal erythroid differentiation and supports erythropoietin (Epo)-independent proliferation. As a first step in understanding the underlying molecular mechanisms we examined the signaling pathways downstream of Ras in primary erythroid cells. We found that 3 major pathways are abnormally activated by oncogenic H-ras: Raf/ERK (extracellular signal-regulated kinase), phosphatidyl inositol 3 (PI3)-kinase/Akt, and RalGEF/RalA. However, only constitutive activation of the MEK (MAPK [mitogen-activated protein kinase]/ERK kinase)/ERK pathway alone could recapitulate all of the effects of oncogenic H-ras expression in blocking erythroid differentiation and inducing Epo-independent proliferation. Although expression of a constitutively active Akt kinase (ca.Akt) in erythroid progenitors does not significantly affect erythroid differentiation in the presence of Epo, coexpression of ca.Akt together with a constitutively active MEK causes prolonged Epo-independent proliferation of erythroid progenitors in addition to a block in differentiation. Moreover, the effects of oncogenic H-ras expression on primary erythroid cells are blocked by the addition of U0126, a specific inhibitor of MEK1 and MEK2, allowing normal terminal erythroid proliferation and differentiation. Our data suggest that the interruption of constitutive MEK/ERK signaling is a potential therapeutic strategy to correct impaired erythroid differentiation in patients with myeloid disorders. (Blood. 2004;104: 1679-1687) CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? Related Article in Blood Online: Too much ERK, not enough erythrocytes Thomas M. Guadagno Blood 2004 104: 1591-1592. [Full Text] [PDF] This article has been cited by other articles: D. M. Gilkes, Y. Pan, D. Coppola, T. Yeatman, G. W. Reuther, and J. Chen Regulation of MDMX Expression by Mitogenic Signaling Mol. Cell. Biol., March 15, 2008; 28(6): 1999 - 2010. [Abstract] [Full Text] [PDF] J. Zhang, Y. Liu, C. Beard, D. A. Tuveson, R. Jaenisch, T. E. Jacks, and H. 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[Abstract] [Full Text] [PDF] N. Omidvar, L. Pearn, A. K. Burnett, and R. L. Darley Ral Is both Necessary and Sufficient for the Inhibition of Myeloid Differentiation Mediated by Ras Mol. Cell. Biol., May 15, 2006; 26(10): 3966 - 3975. [Abstract] [Full Text] [PDF] M. P. Menon, J. Fang, and D. M. Wojchowski Core erythropoietin receptor signals for late erythroblast development Blood, April 1, 2006; 107(7): 2662 - 2672. [Abstract] [Full Text] [PDF] S. Schubbert, K. Lieuw, S. L. Rowe, C. M. Lee, X. Li, M. L. Loh, D. W. Clapp, and K. M. Shannon Functional analysis of leukemia-associated PTPN11 mutations in primary hematopoietic cells Blood, July 1, 2005; 106(1): 311 - 317. [Abstract] [Full Text] [PDF]

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