Protein kinase C theta (PKCθ):: A key player in T cell life and death

Protein kinase C theta (PKC theta) is a member of the novel, Ca2+-independent PKC subfamily, which plays an important and non-redundant role in several aspects of T cell biology. Much progress has been accomplished in understanding the function of PKC theta in the immune system and its unique translocation to the immunological synapse in Ag-stimulated T lymphocytes. Biochemical and genetic approaches revealed that PKC theta is required for the activation of mature T cells as well as for their survival. Mutation of the PKC theta gene leads to impaired receptor-induced stimulation of the transcription factors AP-L NF-kappa B and NFAT, which results in defective T cell activation, and to aberrant expression of apoptosis-related proteins, resulting in poor T cell survival. Furthermore, PKC theta-deficient mice display defects in the differentiation of T helper subsets, particularly in Th2- and Th17-mediated inflammatory responses. Therefore, PKC theta is a critical enzyme that regulates T cell function at multiple stages, and it represents an attractive drug target for allergic and autoimmune diseases. (C) 2007 Elsevier Ltd. All rights reserved.