Protein kinase C-θ: signaling from the center of the T-cell synapse

The hypothesis that protein kinase C (PKC)-θ plays an important role in T-lymphocyte activation, as indicated by numerous studies in cell lines, was recently confirmed in mice deficient in the expression of this enzyme. In response to TCR stimulation, peripheral T cells lacking PKC-θ failed to activate NF-κB and AP-1, and to express IL-2. This revealed a critical function for this PKC family member in linking membrane-proximal activation cascades to transcriptional responses governing T-cell activation. Although the molecular interactions in which PKC-θ engages have not been fully delineated, insights from a variety of recent studies have permitted new models to be formulated regarding the mechanisms through which it achieves its unique effector functions.