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Ral is both necessary and sufficient for the inhibition of myeloid differentiation mediated by Ras

Omidvar, Nader, Pearn, Lorna, Burnett, Alan Kenneth and Darley, Richard Lawrence ORCID: 2006. Ral is both necessary and sufficient for the inhibition of myeloid differentiation mediated by Ras. Molecular and cellular biology 26 (10) , pp. 3966-75. 10.1128/MCB.26.10.3966-3975.2006

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Hyperactivation of Ras is one of the most common abnormalities in acute myeloid leukemia. In experimental models, Ras inhibits myeloid differentiation, which is characteristic of leukemia; however, the mechanism through which it disrupts hematopoiesis is poorly understood. In multipotent FDCP-mix cells, Ras inhibits terminal neutrophil differentiation, thereby indefinitely extending their proliferative potential. Ras also strongly promotes the sensitivity of these cells to granulocyte-macrophage colony-stimulating factor (GM-CSF). Using this model, we have dissected the signaling elements downstream of Ras to determine their relative contribution to the dysregulation of hematopoiesis. Cells expressing Ras mutants selectively activating Raf (Ras*T35S) or phosphatidylinositol 3-kinase (Ras*Y40C) did not significantly affect differentiation or proliferative capacity, whereas Ras*E37G (which selectively activates RalGEFs) perpetuated proliferation and blocked neutrophil development in a manner similar to that of Ras. Correspondingly, expression of constitutively active versions of these effectors confirmed the overriding importance of Ral guanine nucleotide exchange factors. Cells expressing Ras demonstrated hyperactivation of Ral, which itself was able to exactly mimic the phenotype of Ras, including hypersensitivity to GM-CSF. Conversely, dominant negative Ral promoted spontaneous neutrophil development. Ral, in turn, appears to influence differentiation through multiple effectors. These data show, for the first time, the importance of Ral in regulating differentiation and self-renewal in hematopoietic cells.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Additional Information: Pdf uploaded in accordance with publisher's policy at (accessed 25/02/2014)
Publisher: American Society for Microbiology
ISSN: 02707306
Related URLs:
Date of First Compliant Deposit: 30 March 2016
Last Modified: 21 May 2023 16:59

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