Protein Kinase C substrates and pathways
I am studying protein phosphorylation and signal transduction. The protein kinase C (PKC) family of enzymes regulates many processes, including growth, secretion, differentiation, and neuronal function by phosphorylating downstream targets such as ion channels and transcription factors. Neurotransmitters, hormones and growth factors bind G-protein-coupled receptors or receptor tyrosine kinases leading to the stimulation of phospholipases. Phospholipase C generates diacylglycerol (DAG) and together with Ca2+ activates classical (c) PKCs.. Aberrant activation of PKC is linked to tumor promotion. A number of diseases are associated with mutations within PKC genes or misexpression of PKC, for example, ataxia in humans, heart failure in mouse and Parkinsonian syndrome in rat.
A great deal is known regarding structures, activation mechanisms and substrates, however information about in vivo regulation, downstream effectors and the physiological roles of individual PKC isoforms is more limited. I am using a genetic, proteomic and biochemical approach to identify upstream and downstream components of the PKC pathway. I cloned two protein kinase C (PKC) isoforms and a novel protein Kinase (PKL) from the free living nematode worm, Caenorhabditis elegans.
Most biological pathways and genes that are found in humans are present in C. elegans, for example the aging and apoptosis (cell death) pathways were discovered in this worm. I have discovered that the only classical isoform in C.elegans, PKC-2 is essential for normal thermotactic behavioral responses in the worm. My studies have allowed me to determine that PKC-2 is regulated by a cyclic nucleotide gated calcium channel. Using Differential gel electrophotesis (DIGE), I have identified proteins that have shifted mobilities in nematodes that over express PKC-2, indicating alterations in phosphorylation or other post-translational modifications. Characterization of these potential PKC-2 substrates is underway. My studies may lead to the development of new therapeutic agents.
Land, M., Islas, A., Freedman, J.H. and Rubin, C.S. Structure and expression of a novel, neuron-specific protein kinase C (PKC1B) from Caenorhabditis elegans. J. Biol. Chem. 269, 9234-9244, 1994.
Land, M., Islas-Trejo, A. and Rubin, C.S. Origin, Properties, and Regulated Expression of Multiple mRNAs Encoded by the Protein Kinase C1 Gene of Caenorhabditis elegans, J. Biol. Chem. 269, 14820-14827, 1994.
Islas-Trejo, A., Land, M., Tcherepanova, I., Freedman, J.H. and Rubin, C.S. Structure and Expression of the Caenorhabditis elegans Protein Kinase C2 Gene. J. Biol. Chem. 272, 6629-6640, 1997.
Ren, M., Feng, H., Fu, Y., Land, M. and Rubin, C.S., Protein Kinase D is an Essential Regulator of C. elegans Innate Immunity. Immunity. 30, 521- 532 (2009).