Negative regulation of myeloid cell proliferation and function by the SH2 domain-containing tyrosine phosphatase-1.
The SH2 domain containing tyrosine phosphatase SHP-1 has been implicated in the regulation of a multiplicity of signaling pathways involved in hemopoietic cell growth, differentiation, and activation. A pivotal contribution of SHP-1 in the modulation of myeloid cell signaling cascades has been revealed by the demonstration that SHP-1 gene mutation is responsible for the overexpansion and inappropriate activation of myelomonocytic populations in motheaten mice. To investigate the role of SHP-1 in regulation of myeloid leukocytes, an HA epitope-tagged dominant negative (interfering) SHP-1 (SHP-1C453S) was expressed in the myelo-monocytic cell line U937 using the pcDNA3 vector. Overexpression of this protein in SHP-1C453S transfectants was demonstrated by Western blot analysis and by detection of decreased specific activity. Growth, proliferation, and IL-3-induced proliferative responses were substantially increased in the SHP-1C453S-overexpressing cells relative to those in control cells. The results of cell cycle analysis also revealed that the proportion of cells overexpressing SHP-1C453S in S phase was greater than that of control cells. The SHP-1C453S-expressing cells also displayed diminished rates of apoptosis as detected by flow cytometric analysis of propidium iodide-stained cells and terminal deoxynucleotidyltransferase-mediated fluorescein-dUTP nick end-labeling assay. While motility and phagocytosis were not affected by SHP-1C453S overexpression, adhesion and the oxidative burst in response to PMA were enhanced in the SHP-1C453S compared with those in the vector alone transfectants. Taken together, these results suggest that SHP-1 exerts an important negative regulatory influence on cell proliferation and activation while promoting spontaneous cell death in myeloid cells.
Dong
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Q
Department of Medicine, University of Toronto, Ontario, Canada.
Siminovitch
K A
KA
Fialkow
L
L
Fukushima
T
T
Downey
G P
GP
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002448:Cell Adhesion / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D005822:Genetic Vectors / Q000378:metabolism; D006131:Growth Inhibitors / Q000235:genetics / Q000502:physiology*; D006133:Growth Substances / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000201:enzymology / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D054645:Protein Phosphatase 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D016897:Respiratory Burst / Q000235:genetics; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D020298:U937 Cells / Q000201:enzymology; D018909:src Homology Domains / Q000235:genetics
D006131:Growth Inhibitors; D006133:Growth Substances; D047908:Intracellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; D054645:Protein Phosphatase 1; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases