Abstract
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.
Highlights
The NF-B/Rel family of dimeric transcription factors is involved in the immediate early transcription, i.e. independent of protein synthesis, of a large array of genes induced by mitogenic or pathogen-associated stimuli
As for PKC, p21ras activity was constitutively high in endothelial cells cultured in the presence of serum, which was reflected by high MEK1 and extracellular signal-regulated kinase/MAPK activity
We demonstrate that at least in endothelial cells there is an additional regulatory system that controls the transcriptional activity of nuclear NF-B by targeting the RelA subunit
Summary
The NF-B/Rel family of dimeric transcription factors is involved in the immediate early transcription, i.e. independent of protein synthesis, of a large array of genes induced by mitogenic or pathogen-associated stimuli. 1 The abbreviations used are: RHD, Rel homology domain; PKC, protein kinase C; MAPK, mitogen-activated protein kinase; MEK, mitogen-activated protein and extracellular signal-regulated kinase kinase; LPS, bacterial lipopolysaccharide; TNF-␣, tumor necrosis factor-␣; BAEC, bovine aortic endothelial cell(s); PAEC, porcine aortic endothelial cell(s); HUVEC, human umbilical vein endothelial cell(s); PVDF, polyvinylidene difluoride; EC, endothelial cell(s); TET, bacterial tetracycline repressor; PI, phosphatidylinositol. These proteins activate the transcription of NF-B-dependent genes efficiently. Regulation of NF-B activity by PKC, extracellular signal-regulated kinase 1, p38 MAPK, or tyrosine phosphorylation acts downstream of IB without interfering with NF-B nuclear translocation and DNA binding
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
