title: PSTPIP2 dysregulation contributes to aberrant terminal differentiation in GATA-1-deficient megakaryocytes by activating LYN.
abstract: GATA1 mutations are tightly associated with transient myeloproliferative disorder (TMD) and acute megakaryoblstic leukemia (AMKL) in children with Down syndrome. Numerous genes are altered in GATA-1-deficient megakaryocytes, which may contribute to the hyperproliferation and abnormal terminal differentiation of these malignant cells. In this study, we demonstrate that Pstpip2 is a GATA-1-repressed gene that controls megakaryopoiesis. Ectopic expression of PSTPIP2 impaired megakaryocytic differentiation as evidenced by a decrease of CD41 expression and reduced DNA content in K562 cells. PSTPIP2 overexpression also caused enhanced activation of Src family kinases and subsequently reduced ERK phosphorylation. Consistently, PSTPIP2 knockdown showed the opposite effect on differentiation and signaling. Moreover, the W232A mutant of PSTPIP2, defective in its interaction with PEST family phosphatases that recruit c-Src terminal kinase (CSK) to suppress Src family kinases, failed to inhibit differentiation and lost its ability to enhance Src family kinases or reduce ERK phosphorylation. In fact, the W232A mutant of PSTPIP2 promoted megakaryocyte differentiation. These observations suggest that PSTPIP2 recruiting PEST phosphatases somehow blocked CSK activity and led to enhanced activation of Src family kinases and reduced ERK phosphorylation, which ultimately repressed megakaryocyte differentiation. Supporting this idea, PSTPIP2 interacted with LYN and the expression of a dominant negative LYN (LYN DN) overwhelmed the inhibitory effect of PSTPIP2 on differentiation and ERK signaling. In addition, a constitutively active LYN (LYN CA) normalized the enhanced megakaryocyte differentiation and repressed ERK signaling in PSTPIP2 knockdown cells. Finally, we found that PSTPIP2 repressed ERK signaling, differentiation, and proliferation and verified that PSTPIP2 upregulation repressed megakaryocyte development in primary mouse bone marrow cells. Our study thus reveals a novel mechanism by which dysregulation of PSTPIP2 due to GATA-1 deficiency may contribute to abnormal megakaryocyte proliferation and differentiation in pathogenesis of related diseases.
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Wen
authors.affiliation: Hubei International Travel Healthcare Center, Hubei Entry-Exit Inspection and Quarantine Bureau of P. R. China, Wuhan, Hubei, China.
authors.forename: R
authors.initials: R
authors.lastname: Gong
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: L
authors.initials: L
authors.lastname: Gilles
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Stankiewicz
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
authors.forename: M
authors.initials: M
authors.lastname: Guo
authors.affiliation: Department of Hematology, Jiangsu Province Hospital of TCM, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Hematology, Jiangsu Province Hospital of TCM, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Medicine, Division of Hematology and Oncology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Crispino
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D050982:GATA1 Transcription Factor / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D020014:K562 Cells; D008533:Megakaryocytes / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D015398:Signal Transduction; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; C486384:PSTPIP2 protein, human; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases