Protein kinase C epsilon (PKCe) modulates nociceptor sensitization by inflammatory mediators. The overall goal of this project is to identify PKCe substrates that mediate this process. Three candidates are proposed: The alpha subunit of the tetrodotoxin-insensitive sodium channel Nav1.8a, the alpha subunit of the N-type calcium channel Cav2.2a, and the polymodal, vanilloid receptor TRPV1.
The first aim will use a peptide activator of PKCe, the tyeRACK peptide, in gene- targeted mice that have a null mutation in one of these channels to determine if absence of these channels impairs PKCe-mediated nociceptor sensitization. In the second aim we will generate knock-in mice expressing an analog-sensitive mutant of PKCe, PKCe-as, which can be specifically inhibited by an analog of the general kinase inhibitor PP1, 1-Na, and can use benzyl-ATP as a phosphate donor.
The third aim will examine whether channels found to contribute to PKCe- mediated nociceptor sensitization are phosphorylated in a PKCe-dependent pathway using recombinant PKCe-as for in vitro studies and DRG neurons from PKCe-as knock-in mice for cell- based studies. Phosphorylated residues will be identified by mass spectrometry. In the fourth aim identified phosphorylation sites will be mutated and expressed in heterologous systems and in DRG neurons to determine if PKCe regulation of these channels is impaired. These studies will advance our knowledge about mechanisms underlying nociceptor sensitization, identify downstream substrates of PKCe in this process, and provide new potential targets for development of therapeutic agents to treat pain.
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