Protein tyrosine phosphatase SHP-1 positively regulates TLR-induced IL-12p40 production in macrophages through inhibition of phosphatidylinositol 3-kinase.
SHP-1 is a cytoplasm protein tyrosine phosphatase expressed primarily in hematopoietic cells. In the immune system, SHP-1 plays critical roles in regulation of many receptor-mediated signaling cascades, and SHP-1 deficiency in mice causes spontaneous inflammation and autoimmunity. Here, we report a unique requirement for SHP-1 in interleukin-12/23 p40 (IL-12p40) production in response to Toll-like receptor (TLR) stimulation in macrophages. Bone marrow-derived macrophages (BMDMs) lacking significant SHP-1 activity display a profound defect in IL-12p40 synthesis in response to lipopolysaccharide, peptidoglycan, and synthetic TLR ligands, while producing normal amounts of other proinflammatory cytokines, such as TNFalpha and IL-6. Inhibition of SHP-1 function in wild-type BMDMs decreases IL-12p40, and expression of functional SHP-1 protein in mutant cells restores IL-12p40 production following TLR ligation. SHP-1 regulation of IL-12p40 transcription requires both its catalytic activity and phosphotyrosine binding by its N-terminal SH2 domain and is mediated via repression of, and interaction with, phosphatidylinositol 3-kinase, without affecting c-Rel activation. In contrast to normal NF-kappaB activation, SHP-1-defective me(v)/me(v) macrophages display a defect in nucleosome remodeling at the IL-12p40 promoter, and phosphatidylinositol 3-kinase inhibition significantly restores normal nucleosome remodeling in me(v)/me(v) macrophages. Thus, there is a critical role for the tyrosine phosphatase activity of SHP-1 for induction of IL-12p40 production in macrophages in response to TLR ligands, a novel mechanism for host regulation of a specific proinflammatory cytokine important in both innate and adaptive immunity.
Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, California, USA.
Delu
D
Zhou
Cathleen A
CA
Collins
Ping
P
Wu
Eric J
EJ
Brown
D000818:Animals; D002469:Cell Separation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D047468:Immunoprecipitation; D053762:Interleukin-12 Subunit p40 / Q000096:biosynthesis* / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000276:immunology / Q000378:metabolism*; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D051193:Toll-Like Receptors / Q000276:immunology / Q000378:metabolism*
D053762:Interleukin-12 Subunit p40; D051193:Toll-Like Receptors; D019869:Phosphatidylinositol 3-Kinases; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; C509248:Ptpn6 protein, mouse