Regulation of Colony-Stimulating Factor 1 Receptor Signaling by the SH2 Domain-Containing Tyrosine Phosphatase SHPTP1

Abstract

SHPTP1 (PTP1C, HCP, SHP)is an SH2 domain-containing tyrosine phosphatase expressed predominantly in hematopoietic cells. A frameshift mutation in the SHPTP1 gene causes the motheaten (me/me) mouse. These mice are essentially SHPTP1 null and display multiple hematopoietic abnormalities, most prominently hyperproliferation and inappropriate activation of granulocytes and macrophages. The me/me phenotype suggests that SHPTP1 negatively regulates macrophage proliferative pathways. Using primary bone marrowderived macrophages from me/me mice and normal littermates, we examined the role of SHPTP1 in regulating signaling by the major macrophage mitogen colony-stimulating factor 1 (CSF-1) (also known as macrophage colony-stimulating factor). Macrophages from me/me mice hyperproliferate in response to CSF-1. In the absence of SHPTP1, the CSF-1 receptor (CSF-1R) is hyperphosphorylated upon CSF-1 stimulation, suggesting that SHPTP1 dephosphorylates the CSF-1R. At least some CSF-1R-associated proteins also are hyperactivated. SHPTP1 is associated constitutively, via its SH2 domains, with an unidentified 130-kDa phosphotyrosyl protein (P130). P130 and SHPTP1 are further tyrosyl phosphorylated upon CSF-1 stimulation. Tyrosylphosphorylated SHPTP1 binds to Grb2 via the Grb2 SH2 domain. Moreover, in me/me macrophages, Grb2 is associated, via its SH3 domains, with several tyrosyl phosphoproteins. These proteins are hyperphosphorylated on tyrosyl residues in me/me macrophages, suggesting that Grb2 may recruit substrates for SHPTP1. Our results indicate that SHPTP1 is a critical negative regulator of CSF-1 signaling in vivo and suggest a potential new function for Grb2.

The Role of C-terminal Tyrosine Phosphorylation in the Regulation of SHP-1 Explored via Expressed Protein Ligation

“…The immobilized SHP-1 fusion proteins were ligated to synthetic peptides in the presence of 2% thiophenol. 2 The purity of the semisynthetic proteins was determined by 10% SDS-PAGE stained with Coomassie Blue and by MALDI mass spectrometry (Ͼ90%). The yield was 2-10 mg of protein/liter in E. coli cell culture as revealed by Bradford assay (24).…”

Regulation of theLeishmania-induced innate inflammatory response by the protein tyrosine phosphatase SHP-1

“…In a subsequent study [11], we demonstrated that this pV-mediated protection against leishmaniasis was in part due to an increased production of nitric oxide and pro-inflammatory molecules (such as IL-6, IL-1b, MCP-1/CCL2 and MIP-2/CXCL1), accompanied by increased leukocyte recruitment. Furthermore, we showed that the PTP Src homology 2 domain phosphotyrosine phosphatase 1 (SHP-1), recognized as a negative regulator of numerous phosphotyrosine-dependent signaling pathways in hematopoietic cells [12][13][14][15][16][17], is specifically induced by Leishmania infection and involved in the deactivation of the IFN-c-induced JAK2-dependent signaling pathway [6].…”

SHP-1 Regulation of p62DOK Tyrosine Phosphorylation in Macrophages

“…Previous studies of bone-marrow macrophages from me/me and wild-type mice have suggested that SHP-1 regulates interferon-␣-induced Jak-Stat signaling (30) as well as CSF-1-induced tyrosine phosphorylation and cell proliferation (31), and associates constitutively with an unidentified 130-kDa phosphotyrosyl protein (pp130) (31). Subsequently, pp130 was shown to be a membrane-spanning glycoprotein and a substrate of SHP-1 in macrophages and was identified as comprising p91/PIR-B (32,33), a recently cloned ITIM-containing inhibitory receptor (34,35) and SHPS-1 (36), or the SHPS-1-related protein BIT (32).…”