Regulation of NF-kappaB RelA phosphorylation and transcriptional activity by p21(ras) and protein kinase Czeta in primary endothelial cells.
The activity of the transcription factor NF-kappaB is thought to be regulated mainly through cytoplasmic retention by IkappaB molecules. Here we present evidence of a second mechanism of regulation acting on NF-kappaB after release from IkappaB. In endothelial cells this mechanism involves phosphorylation of the RelA subunit of NF-kappaB through a pathway involving activation of protein kinase Czeta (PKCzeta) and p21(ras). We show that transcriptional activity of RelA is dependent on phosphorylation of the N-terminal Rel homology domain but not the C-terminal transactivation domain. Inhibition of phosphorylation by dominant negative mutants of PKCzeta or p21(ras) results in loss of RelA transcriptional activity without interfering with DNA binding. Raf/MEK, small GTPases, phosphatidylinositol 3-kinase, and stress-activated protein kinase pathways are not involved in this mechanism of regulation.
Anrather
J
J
Immunobiology Research Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA. janarthe@caregrouyp.harvard.edu
Csizmadia
V
V
Soares
M P
MP
Winkler
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D017931:DNA Primers; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D051996:Transcription Factor RelA; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000099221:Protein Kinase C zeta
D017931:DNA Primers; D020558:GTP Phosphohydrolases; D016328:NF-kappa B; D015689:Oncogene Protein p21(ras); D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D019908:Proto-Oncogene Proteins c-raf; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta