Regulation of PKC-Θ function by phosphorylation in T cell receptor signaling

Protein kinase C (PKC)-Θ is a serine/threonine kinase belonging to the calcium-independent novel PKC subfamily; its expression is restricted to certain tissues and cell types, including T cells. The signals delivered from T cell receptor (TCR) and CD28 costimulatory molecules trigger PKC-Θ catalytic activation and membrane translocation to the immunological synapse, leading to activation of NF-κB, AP-1, and NF-AT.These transcription factors are important forT cell survival, activation, and differentiation. Phosphorylation of PKC-Θ at multiple Ser/Thr/Tyr residues is induced inT cells duringTCR signaling. Some phosphorylation sites play critical roles in the regulation of PKC-Θ function and downstream signaling. The regulation mechanisms for PKC-Θ phosphorylation sites are now being revealed. In this review, we discuss the current understanding of the regulation of PKC-Θ function by phosphorylation duringTCR signaling.