Lyn-and PLC-β3-dependent regulation of SHP-1 phosphorylation controls Stat5 activity and myelomonocytic leukemia-like disease

Abstract

Hyperactivation of the transcription factor Stat5 leads to various leukemias. Stat5 activity is regulated by the protein phosphatase SHP-1 in a phospholipase C (PLC)-β3-dependent manner. Thus, PLC-β3-deficient mice develop myeloproliferative neoplasm, like Lyn (Src family kinase)-deficient mice. Here we show that Lyn/PLC-β3 doubly deficient lyn-/-;PLC- β3-/- mice develop a Stat5-dependent, fatal myelodysplastic/ myeloproliferative neoplasm, similar to human chronic myelomonocytic leukemia (CMML). In hematopoietic stem cells of lyn-/-;PLC-β3 -/- mice that cause the CMML-like disease, phosphorylation of SHP-1 at Tyr536 and Tyr564 is abrogated, resulting in reduced phosphatase activity and constitutive activation of Stat5. Furthermore, SHP-1 phosphorylation at Tyr564 by Lyn is indispensable for maximal phosphatase activity and for suppression of the CMML-like disease in these mice. On the other hand, Tyr536 in SHP-1 can be phosphorylated by Lyn and another kinase(s) and is necessary for efficient interaction with Stat5. Therefore, we identify a novel Lyn/PLC-β3-mediated regulatory mechanism of SHP-1 and Stat5 activities. © 2010 by The American Society of Hematology.