The yin and yang of protein kinase C-theta (PKC?): a novel drug target for selective immunosuppression.

ABSTRACT: Protein kinase C-theta (PKC?) is a protein kinase C (PKC) family member expressed predominantly in T lymphocytes, and extensive studies addressing its function have been conducted. PKC? is the only T cell-expressed PKC that localizes selectively to the center of the immunological synapse (IS) following conventional T cell antigen stimulation, and this unique localization is essential for PKC?-mediated downstream signaling. While playing a minor role in T cell development, early in vitro studies relying, among others, on the use of PKC?-deficient (Prkcq(-/-)) T cells revealed that PKC? is required for the activation and proliferation of mature T cells, reflecting its importance in activating the transcription factors nuclear factor kappa B, activator protein-1, and nuclear factor of activated T cells, as well as for the survival of activated T cells. Upon subsequent analysis of in vivo immune responses in Prkcq(-/-) mice, it became clear that PKC? has a selective role in the immune system: it is required for experimental Th2- and Th17-mediated allergic and autoimmune diseases, respectively, and for alloimmune responses, but is dispensable for protective responses against pathogens and for graft-versus-leukemia responses. Surprisingly, PKC? was recently found to be excluded from the IS of regulatory T cells and to negatively regulate their suppressive function. These attributes of PKC? make it an attractive target for catalytic or allosteric inhibitors that are expected to selectively suppress harmful inflammatory and alloimmune responses without interfering with beneficial immunity to infections. Early progress in developing such drugs is being made, but additional studies on the role of PKC? in the human immune system are urgently needed.

SUBMITTER: Zhang EY 

PROVIDER: S-EPMC3903317 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature