A negative role of SHP-2 tyrosine phosphatase in growth factor-dependent hematopoietic cell survival.
SHP-2 tyrosine phosphatase is highly expressed in hematopoietic cells; however, the function of SHP-2 in hematopoietic cell processes is not fully understood. Recent identification of SHP-2 mutations in childhood leukemia further emphasizes the importance of SHP-2 regulation in hematopoietic cells. We previously reported that SHP-2 played a positive role in IL-3-induced activation of Jak2 kinase in a catalytic-dependent manner. Interestingly, enforced expression of wild-type (WT) SHP-2 in Ba/F3 cells enhanced growth factor deprivation-induced apoptosis. Biochemical analyses revealed that although IL-3 activation of Jak2 kinase was increased, tyrosyl phosphorylation of its downstream substrate STAT5 was disproportionately decreased by the overexpression of SHP-2. Following IL-3 deprivation, the tyrosyl phosphorylation of STAT5 that is required for its antiapoptotic activity was rapidly diminished in SHP-2 overexpressing cells. As a result, reduction of the putative downstream targets of STAT5-Bcl-X(L) and pim-1 was accelerated by overexpression of SHP-2. Further investigation showed that SHP-2 associated with STAT5, and that it was indeed able to dephosphorylate STAT5. Finally, overexpression of SHP-2 in primary bone marrow hematopoietic progenitor cells compromised their differentiative and proliferative potential, and enhanced growth factor withdrawal-induced cell death. And, the effect of SHP-2 overexpression on growth factor-dependent survival was diminished in STAT5-deficient hematopoietic cells. Taken together, these results suggest that SHP-2 tyrosine phosphatase negatively regulates hematopoietic cell survival by dephosphorylation of STAT5.
Chen
Jing
J
Department of Hematopoiesis, Jerome H Holland Laboratory for the Biomedical Sciences, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.
Yu
Wen-Mei
WM
Bunting
Kevin D
KD
Qu
Cheng-Kui
CK
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D006133:Growth Substances / Q000378:metabolism*; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D053614:Janus Kinase 2; D051379:Mice; D008894:Milk Proteins; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D006133:Growth Substances; D047908:Intracellular Signaling Peptides and Proteins; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse