Kyushu University · Medicine
Professor Yoshinori Fukui's research lab focuses on signal transduction mechanisms in immune cells and cancer biology, with a central emphasis on the roles of phosphoinositide kinases, Rho GTPase regulators like DOCK2, and oncogenic tyrosine kinases in cellular signaling. The lab investigates how lipid second messengers and scaffolding proteins spatially and temporally regulate cell migration, immune activation, and oncogenic transformation. Key research directions include the molecular mechanisms of DOCK2-mediated Rac activation in neutrophils and plasmacytoid dendritic cells, and the interplay between tyrosine kinases such as v-Src and phosphatidylinositol 3-kinase in signal transduction and cytoskeletal organization. The lab integrates biochemical, cell biological, and imaging approaches to dissect signaling networks in immunity and disease.
Figures are computed from collected data and may differ slightly.
During chemotaxis, activation of the small guanosine triphosphatase Rac is spatially regulated to organize the extension of membrane protrusions in the direction of migration. In neutrophils, Rac activation is primarily mediated by DOCK2, an atypical guanine nucleotide exchange factor. Upon stimulation, we found that DOCK2 rapidly translocated to the plasma membrane in a phosphatidylinositol 3,4,5-trisphosphate-dependent manner. However, subsequent accumulation of DOCK2 at the leading edge requi
Immunoprecipitates of p60v-src proteins from chicken embryo fibroblasts infected with Rous sarcoma virus were assayed for phosphatidylinositol (PI) kinase activity in the absence of detergents. The product of the PI kinase reaction, phosphatidylinositol monophosphate (PIP), migrated slightly slower than did the authentic phosphatidylinositol-4-monophosphate marker in thin-layer chromatography and was indistinguishable from phosphatidylinositol-3-monophosphate produced by PI kinase type I. Furthe
Plasmacytoid dendritic cells (pDCs) play a key role in antiviral immunity, but also contribute to the pathogenesis of certain autoimmune diseases, by producing large amounts of type I IFNs. Although activation of pDCs is triggered by engagement of nucleotide-sensing toll-like receptors (TLR) 7 and 9, type I IFN induction additionally requires IkappaB kinase (IKK) alpha-dependent activation of IFN regulatory factor (IRF) 7. However, the signaling pathway mediating IKK-alpha activation is poorly d
We have assayed immunoprecipitates of several oncogene products from retrovirally infected chicken embryo fibroblasts (CEF) for phosphatidylinositol (PI) kinase activity. Immunoprecipitates of P68gag-ros, P130gag-tps, P47gag-crk, polyoma middle T (mT)-p60c-src complex, and mT-p62c-yrs complex exhibited PI kinase activity when assayed without detergents. This activity was sensitive to the nonionic detergent, Triton X-100, and the product was indistinguishable from phosphatidylinositol-3-phosphate
When purified p60v-src was mixed with lysates of chicken embryo fibroblasts and immunoprecipitated with anti-Src antibody, phosphatidylinositol (PI)-3 kinase activity was found to be present in the Src protein immunoprecipitates. The level of bound PI-3 kinase activity was 5 to 10 times higher in lysates obtained from cells transformed by the src, fps, or yes oncogene than in lysates of uninfected cells. This increase in associated PI-3 kinase activity appears to be due to increased binding of t
p60v-src has been shown to associate with a detergent-insoluble cellular matrix containing cytoskeletal proteins, but p60c-src does not bind to this matrix. We analyzed the association of mutant src proteins with the matrix and found that mutants which lack an amino-terminal portion (residues 149 to 169) of the SH2 domain cannot bind to the matrix. Neither the SH3 region nor other portions of the SH2 region were required for association. We also tested protein kinase-defective mutants and chimer
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