Protein phosphorylation is an essential part of the activating and regulatory processes in the functioning and responses for a variety of cells. Attention has been paid to protein phosphorylation in neutrophils because of the importance of this leukocyte in defense against infection and in a number of allergic and non-allergic tissue-damaging inflammatory reactions. The ultimate purpose of the proposed investigation is to identify, isolate and characterize those proteins which are phosphorylated when neutrophils are stimulated by chemotactic factors, cytokines and crosslinking of Fc receptors and the respective protein kinases for which they are responsible. Attempts will be made to identify the function of phosphorylated proteins, the role that phosphorylation plays in these respective functions and what role the proteins and their phosphorylation play in neutrophil stimulus-response coupling. For these purposes, the following studies are being pursued:

(1) To define the varieties of neutrophil protein kinases (tyrosine protein kinases, mitogen-activated protein kinase (MAP kinase), MAP kinase-activated protein kinase 2, calcium/calmodulin-dependent protein kinase, histone H4 protein kinase, protein kinase C and others); the regulation and the mechanism of activation of these kinases and their respective substrates in various subcellular fractions of neutrophils.

(2) To define the phosphoproteins, the phosphorylation levels of which are regulated by chemotactic factors (fMet-Leu-Phe), cytokines, crosslinking of Fc receptors, calcium ionophores and phorbol esters in intact neutrophils. Attempts will be made to identify and characterize the molecular components (protein kinases and their substrates) of the physiologically important phosphorylation system in neutrophils.

Wu, Y., Hannigan, M., Kotlyarov, A., Gaestel, M., Wu, D., Huang, C-K. (2004) A requirement of MAPKAPK2 in the uropod localization of PTGN during fMLP-induced neutrophil chemotaxis. Biochem. Biophys. Res. Commun. 316:666-672.

Li, Z., Hannigan, M., Mo, Z., Liu, B., Lu, W., Smrcka, A..V., Wu, G., Liu, M., Huang, C-K. and Wu, D. (2003) Directional sensing requires Gbg-mediated PAK1 and PIXa-dependent activation of cdc42. Cell 114:215-227.

Hannigan, M.O., Huang, C-K., and Wu, D.(2003) Roles of PI3K in neutrophil function. Curr. Topics in Microbiology and Immunology 282:166-175.

Hannigan, M., Zhan, L., Zhong Li, Ai. Y., Wu, D. and Huang, C-K. (2002) Neutrophils lacking phosphoinositide 3-kinase g show loss of directionality during N-formyl-Met-Leu-Phe-induced chemotaxis. Proc. Natl. Acad. Sci. 99:3603-3608.

Mathews, E.E., Dunn, B. D., Hannigan, M.O., Huang, C-K., and Lester, E.H. (2002) Genetic control of neutrophil superoxide burst activity in diabetes resistant Alr/Lt mice Free Radical Biol and Medicine 32:744-751.

Hannigan M.O., Zhan, L., Ai, Y., Kotlyarov, A., Gaestel, M. and Huang, C-K. (2001) Abnormal migration phenotype of MAPKAP kinase 2-/- neutrophils in Zigmond chambers containing fMLP gradients. J. Immunol. 167:3953-3961.

Cochrane, R., Clark, R.B., Huang, C-K., Cone, R.E. (2001) Differential regulation of T cell receptor-mediated Th1 cell IFN-g production and proliferation by divergent cAMP-mediation redox pathway. J. Interferon and Cytokine Research 21:797-807.