Phosphorylation-dephosphorylation of proteins is one of the most important mechanisms for the regulation of cellular functions. Protein kinase C, a Ca2+/phospholipid-dependent protein kinase, has emerged as a pivotal regulatory element for cell growth, differentiation, gene expression, hormone secretion, cell surface receptor function, and cellular metabloism. This protein kinase can be activated by diacylglycerol, a second messenger generated by signal-induced breakdown of phosphoinositides. In addition, it has been identified as a receptor for tumor-promoting phorbol esters which elicit pleiotropic responses comparable to those by many hormones and growth factors. Three isozymic forms of rat brain protein kinase C have been purified to near homogeneity. Polyclonal and monoclonal antibodies against these enzymes were prepared for the immunochemical characterization. These isozymes are distinguishable by peptide mapping and immunological analysis, indicating that they are products of different genes. The various protein kinase C isozymes were found to be enriched in different regions of rat brain and expressed differentially during brain development. Activation of protein kinase C in cells was studied by using EL4 thymoma cells which can be induced to secret interleukin-2 in response to tumor-promoting phorbol esters. These compounds promote the translocation of protein kinase C from cytosol to the particulate fraction and a rapid degradation of the enzyme. The phorbol ester-induced translocation and degradation of protein kinase C may be early events in the secretion of interleukin-2. In vitro, tryptic degradation of purified protein kinase C generates active forms of the kinase and phorbol ester-binding protein that are active in the absence of Ca2+. The structure-function relationships of protein kinase C were investigated by using monoclonal antibody specific for the phorbol ester-binding domain. This antibody reduces the binding of phorbol ester to the enzyme without inhibiting the kinase activity. Protein kinase C activity was shown to be regulated by autophosphorylation, and the resulting phosphorylated kinase exhibited higher affinity for Ca2+ and phorbol esters.

Project Start
Project End
Budget Start
Budget End
Support Year
7
Fiscal Year
1986
Total Cost
Indirect Cost
Name
U.S. National Inst/Child Hlth/Human Dev
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Huang, Freesia L; Huang, Kuo-Ping; Boucheron, Catherine (2007) Long-term enrichment enhances the cognitive behavior of the aging neurogranin null mice without affecting their hippocampal LTP. Learn Mem 14:512-9
Huang, Kuo-Ping; Huang, Freesia L; Shetty, Pavan K et al. (2007) Modification of protein by disulfide S-monoxide and disulfide S-dioxide: distinctive effects on PKC. Biochemistry 46:1961-71
Huang, Freesia L; Huang, Kuo-Ping; Wu, Junfang et al. (2006) Environmental enrichment enhances neurogranin expression and hippocampal learning and memory but fails to rescue the impairments of neurogranin null mutant mice. J Neurosci 26:6230-7
Huang, Kuo-Ping; Huang, Freesia L; Jager, Tino et al. (2004) Neurogranin/RC3 enhances long-term potentiation and learning by promoting calcium-mediated signaling. J Neurosci 24:10660-9
Wu, Junfang; Huang, Kuo-Ping; Huang, Freesia L (2003) Participation of NMDA-mediated phosphorylation and oxidation of neurogranin in the regulation of Ca2+- and Ca2+/calmodulin-dependent neuronal signaling in the hippocampus. J Neurochem 86:1524-33
Wu, Junfang; Li, Junfa; Huang, Kuo-Ping et al. (2002) Attenuation of protein kinase C and cAMP-dependent protein kinase signal transduction in the neurogranin knockout mouse. J Biol Chem 277:19498-505
Watson, J B; Khorasani, H; Persson, A et al. (2002) Age-related deficits in long-term potentiation are insensitive to hydrogen peroxide: coincidence with enhanced autophosphorylation of Ca2+/calmodulin-dependent protein kinase II. J Neurosci Res 70:298-308
Miyakawa, T; Yared, E; Pak, J H et al. (2001) Neurogranin null mutant mice display performance deficits on spatial learning tasks with anxiety related components. Hippocampus 11:763-75
Li, J; Huang, F L; Huang, K P (2001) Glutathiolation of proteins by glutathione disulfide S-oxide derived from S-nitrosoglutathione. Modifications of rat brain neurogranin/RC3 and neuromodulin/GAP-43. J Biol Chem 276:3098-105
Xiao, D M; Pak, J H; Wang, X et al. (2000) Phosphorylation of HMG-I by protein kinase C attenuates its binding affinity to the promoter regions of protein kinase C gamma and neurogranin/RC3 genes. J Neurochem 74:392-9

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