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Protein kinase C beta controls nuclear factor kappaB activation in B cells through selective regulation of the IkappaB kinase alpha.

Activation of the nuclear factor (NF)-kappaB transcription complex by signals derived from the surface expressed B cell antigen receptor controls B cell development, survival, and antigenic responses. Activation of NF-kappaB is critically dependent on serine phosphorylation of the IkappaB protein by the multi-component IkappaB kinase (IKK) containing two catalytic subunits (IKKalpha and IKKbeta) and one regulatory subunit (IKKgamma). Using mice deficient for protein kinase C beta (PKCbeta) we show an essential role of PKCbeta in the phosphorylation of IKKalpha and the subsequent activation of NF-kappaB in B cells. Defective IKKalpha phosphorylation correlates with impaired B cell antigen receptor-mediated induction of the pro-survival protein Bcl-xL. Lack of IKKalpha phosphorylation and defective NF-kappaB induction in the absence of PKCbeta explains the similarity in immunodeficiencies caused by PKCbeta or IKKalpha ablation in B cells. Furthermore, the well established functional cooperation between the protein tyrosine kinase Bruton's tyrosine kinase (Btk), which regulates the activity of NF-kappaB and PKCbeta, suggests PKCbeta as a likely serine/threonine kinase component of the Btk-dependent NF-kappaB activating signal transduction chain downstream of the BCR.

Pubmed ID: 12070292

Authors

  • Saijo K
  • Mecklenbräuker I
  • Santana A
  • Leitger M
  • Schmedt C
  • Tarakhovsky A

Journal

The Journal of experimental medicine

Publication Data

June 17, 2002

Associated Grants

None

Mesh Terms

  • Animals
  • B-Lymphocytes
  • I-kappa B Kinase
  • Isoenzymes
  • Mice
  • Mice, Inbred C57BL
  • NF-kappa B
  • Phosphorylation
  • Protein Kinase C
  • Protein Kinase C beta
  • Protein-Serine-Threonine Kinases