Role of vav1- and src-related Tyrosine Kinases in Macrophage Activation by CpG DNA

• Published in: The Journal of biological chemistry 2004-04, Vol.279 (14), p.13809-13816
• Main Authors: Stovall, Stephanie H, Yi, Ae-Kyung, Meals, Elizabeth A, Talati, Ajay J, Godambe, Sandip A, English, B Keith
• Format: Article
• Language: English
• Subjects: Animals; Cell Cycle Proteins; Cell Line; CpG Islands - physiology; Macrophages - cytology; Macrophages - enzymology; Mitogen-Activated Protein Kinases - metabolism; Mutation; NF-kappa B - metabolism; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Phosphorylation; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-vav; Pyrazoles - metabolism; Pyrimidines - metabolism; src-Family Kinases - metabolism; Tumor Necrosis Factor-alpha - metabolism; Tyrosine - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M311434200

Macrophage activation by CpG DNA requires toll-like receptor 9 and the adaptor protein MyD88. Gram-negative bacterial lipopolysaccharide also activates macrophages via a toll-like receptor pathway (TLR-4), but we and others have reported that lipopolysaccharide also stimulates tyrosine phosphorylation in macrophages. Herein we report that exposure of RAW 264.7 murine macrophages to CpG DNA (but not non-CpG DNA) provoked the rapid tyrosine phosphorylation of vav1 . PP1, a selective inhibitor of src -related tyrosine kinases, blocked both the CpG DNA-mediated tyrosine phosphorylation of vav1 and the CpG DNA-mediated up-regulation of macrophage tumor necrosis factor secretion and inducible nitric-oxide synthase protein accumulation. Furthermore, we found that the inducible expression of any of three dominant interfering mutants of vav1 (a truncated protein, vav C; a form containing a point mutation in the regulatory tyrosine residue, vav YF174; and a form with an in-frame deletion of six amino acids required for the guanidine nucleotide exchange factor (GEF) activity of vav1 for rac family GTPases, vav GEFmt) consistently inhibited CpG DNA-mediated up-regulation of tumor necrosis factor secretion and inducible nitric-oxide synthase protein accumulation in RAW-TT10 macrophages. Finally, we determined that CpG DNA-mediated up-regulation of NF-κB activity (but not mitogen-activated protein kinase activation) was inhibited by preincubation with PP1 or by expression of the truncated vav C mutant. Taken together, our results indicate that the tyrosine phosphorylation of vav1 by a src -related tyrosine kinase or kinases plays an important role in the macrophage response to CpG DNA.