Effects of a leukemia-associated gain-of-function mutation of SHP-2 phosphatase on interleukin-3 signaling.
Mutations in SHP-2 phosphatase that cause hyperactivation of its catalytic activity have been identified in human leukemias, particularly juvenile myelomonocytic leukemia, which is characterized by hypersensitivity of myeloid progenitor cells to granulocyte macrophage colony-stimulating factor and interleukin (IL)-3. However, the molecular mechanisms by which gain-of-function (GOF) mutations of SHP-2 induce hematopoietic malignancies are not fully understood. Our previous studies have shown that SHP-2 plays an essential role in IL-3 signal transduction in both catalytic-dependent and -independent manners and that overexpression (5-6-fold) of wild type (WT) SHP-2 attenuates IL-3-mediated hematopoietic cell function through accelerated dephosphorylation of STAT5. These results raised the possibility that SHP-2-associated leukemias are not solely attributed to the increased catalytic activity of GOF mutant SHP-2. GOF mutant SHP-2 must have gained additional capacities. To test this possibility, we investigated effects of a GOF mutation of SHP-2 (SHP-2 E76K) on hematopoietic cell function and IL-3 signal transduction by comparing with those of overexpressed WT SHP-2. Our results showed that SHP-2 E76K mutation caused myeloproliferative disease in mice, while overexpression of WT SHP-2 decreased hematopoietic potential of the transduced cells in recipient animals. The E76K mutation in the N-terminal Src homology 2 domain increased interactions of mutant SHP-2 with Grb2, Gab2, and p85, leading to hyperactivation of IL-3-induced Erk and phosphatidylinositol 3-kinase (PI3K) pathways. In addition, despite the substantial increase in the catalytic activity, dephosphorylation of STAT5 by SHP-2 E76K was dampened. Furthermore, catalytically inactive SHP-2 E76K with an additional C459S mutation retained the capability to increase the interaction with Gab2 and to enhance the activation of the PI3K pathway. Taken together, these studies suggest that in addition to the elevated catalytic activity, fundamental changes in physical and functional interactions between GOF mutant SHP-2 and signaling partners also play an important role in SHP-2-related leukemigenesis.
Yu
Wen-Mei
WM
Department of Medicine, Division of Hematology/Oncology, Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
Daino
Hanako
H
Chen
Jing
J
Bunting
Kevin D
KD
Qu
Cheng-Kui
CK
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D017690:Cell Transplantation; D002478:Cells, Cultured; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D051380:GRB2 Adaptor Protein / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D053614:Janus Kinase 2; D007938:Leukemia / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C490894:Gab2 protein, mouse; C495949:Grb2 protein, mouse; D007377:Interleukin-3; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D051058:Oncogene Protein v-akt; D048049:Extracellular Signal-Regulated MAP Kinases; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse