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Correspondence to: Hal E. Broxmeyer, Department of Microbiology/Immunology and the Walther Oncology Center, Indiana University School of Medicine, Bldg. R4, Rm. 302, 1044 West Walnut St., Indianapolis, IN 46202. Tel:317-274-7510 Fax:317-274-7592 E-mail:hbroxmey{at}iupui.edu.
Chemokines regulate a number of biological processes, including trafficking of diverse leukocytes and proliferation of myeloid progenitor cells. SHP-1 (Src homology 2 domain tyrosine phosphatase 1), a phosphotyrosine phosphatase, is considered an important regulator of signaling for a number of cytokine receptors. Since specific tyrosine phosphorylation of proteins is important for biological activities induced by chemokines, we examined the role of SHP-1 in functions of chemokines using viable motheaten (mev/mev) mice that were deficient in SHP-1. Chemotactic responses to stromal callderived factor 1 (SDF-1), a CXC chemokine, were enhanced with bone marrow myeloid progenitor cells as well as macrophages, T cells, and B cells from mev/mev versus wild-type (+/+) mice. SDF-1dependent actin polymerization and activation of mitogen-activated protein kinases were also greater in mev/mev versus +/+ cells. In contrast, immature subsets of mev/mev bone marrow myeloid progenitors were resistant to effects of a number of chemokines that suppressed proliferation of +/+ progenitors. These altered chemokine responses did not appear to be due to enhanced expression of CXCR4 or lack of chemokine receptor expression. However, expression of some chemokine receptors (CCR1, CCR2, CCR3, and CXCR2) was significantly enhanced in mev/mev T cells. Our results implicate SHP-1 involvement in a number of different chemokine-induced biological activities.
Key Words: chemokine, Src homology 2 domain tyrosine phosphatase 1, viable motheaten mice, chemotaxis, myelosuppression, stromal cellderived factor 1
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