Abstract
G protein βγ subunit-dependent signaling is important for chemoattractant-dependent leukocyte chemotaxis. Selective small molecule targeting of phosphoinositide 3-kinase (PI3-kinase) γ catalytic activity is a target of interest for anti-inflammatory pharmaceutical development. In this study, we examined whether small-molecule inhibition of Gβγ-dependent signaling, including Gβγ-dependent activation of PI3-kinase γ and Rac1, could inhibit chemoattractant-dependent neutrophil migration in vitro and inflammation in vivo. Small-molecule Gβγ inhibitors suppressed fMLP-stimulated Rac activation, superoxide production, and PI3-kinase activation in differentiated HL60 cells. These compounds also blocked fMLP-dependent chemotaxis in HL60 cells and primary human neutrophils. Systemic administration inhibited paw edema and neutrophil infiltration in a mouse carrageenan-induced paw edema model. Overall, the data demonstrate that targeting Gβγ-regulation may be an effective anti-inflammation strategy.
Footnotes
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Supported by National Institutes of Health grants GM60286 (A.V.S.) and Postdoctoral Training grant in Cancer Biology (D.M.L.) the Johnson and Johnson Discovery Fund (A.V.S.), and an Arthritis Foundation Postdoctoral Fellowship (D.M.L.).
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ABBREVIATIONS: GPCR, G protein-coupled receptor; PI3, phosphoinositide 3; PLC, phospholipase C; P-Rex, phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchange factor; PIP3, phosphatidylinositol 3,4,5-trisphosphate; bGβγ, N terminally biotinylated Gβγ; fMLP, formyl-Met-Leu-Phe; ELISA, enzyme-linked immunosorbent assay; DMSO, dimethyl sulfoxide; HRP, horseradish peroxidase; HBSS, Hanks' balanced saline solution; GM-CSF, granulocyte-macrophage-colony stimulating factor; IL, interleukin; NBT, nitro blue tetrazolium; PMA, phorbol 12-myristate 13-acetate; GFP-PH-Akt, Green fluorescent protein fusion with the pleckstrin homology domain from Akt protein kinase; ANOVA, analysis of variance.
- Received September 14, 2007.
- Accepted November 13, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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