Diacylglycerol kinase α enhances protein kinase Cζ-dependent phosphorylation at Ser311 of p65/RelA subunit of nuclear factor-κB

We recently reported that diacylglycerol kinase (DGK) alpha enhanced tumor necrosis factor-alpha (TNF-alpha)-induced activation of nuclear factor-kappa B (NF-kappa B). However, the signaling pathway between DGK alpha and NF-kappa B remains unclear. Here, we found that small interfering RNA-mediated knockdown of DGK alpha strongly attenuated protein kinase C (PKC) zeta-dependent phosphorylation of a large subunit of NF-kappa B, p65/RelA, at Ser311 but not PKC zeta-independent phosphorylation at Ser468 or Ser536. Moreover, knockdown and overexpression of PKC zeta suppressed and synergistically enhanced DGK alpha-mediated NF-kappa B activation, respectively. These results strongly suggest that DGKa positively regulates TNF-alpha-dependent NF-kappa B activation via the PKC zeta-mediated Ser311 phosphorylation of p65/RelA. (C) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.