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

Adv Pharmacol. 2013;66:267-312. doi: 10.1016/B978-0-12-404717-4.00006-8.

Abstract

Protein kinase C-theta (PKCθ) is a protein kinase C (PKC) family member expressed predominantly in T lymphocytes, and extensive studies addressing its function have been conducted. PKCθ 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 PKCθ-mediated downstream signaling. While playing a minor role in T cell development, early in vitro studies relying, among others, on the use of PKCθ-deficient (Prkcq(-/-)) T cells revealed that PKCθ 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 PKCθ 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, PKCθ was recently found to be excluded from the IS of regulatory T cells and to negatively regulate their suppressive function. These attributes of PKCθ 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 PKCθ in the human immune system are urgently needed.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Autoimmune Diseases / drug therapy
  • Autoimmune Diseases / immunology
  • Autoimmune Diseases / metabolism
  • Humans
  • Immune System Diseases / drug therapy
  • Immune System Diseases / immunology*
  • Immune System Diseases / metabolism
  • Immune Tolerance* / drug effects
  • Immunological Synapses / drug effects
  • Immunological Synapses / immunology
  • Immunological Synapses / metabolism*
  • Immunosuppressive Agents / pharmacology
  • Immunosuppressive Agents / therapeutic use
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / chemistry
  • Isoenzymes / metabolism*
  • Molecular Targeted Therapy
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / chemistry
  • Protein Kinase C / metabolism*
  • Protein Kinase C-theta
  • Signal Transduction* / drug effects

Substances

  • Immunosuppressive Agents
  • Isoenzymes
  • PRKCQ protein, human
  • Protein Kinase C
  • Protein Kinase C-theta