Identification of signal-induced IkappaB-alpha kinases in human endothelial cells.
Activation of the nuclear transcription factor-kappaB is an early event in endothelial activation. NF-kappaB activation is regulated by the inducible phosphorylation and subsequent degradation of the inhibitory subunit IkappaB-alpha. We identified two discrete kinases of approximately 36 and 41 kDa in the cytoplasm of human umbilical vein endothelial cells that specifically bind to and phosphorylate the IkappaB-alpha subunit. IkappaB-alpha kinase activity is transiently elevated following treatment with either tumor necrosis factor alpha, interleukin-1beta, or bacterial lipopolysaccharides and precedes activation of either mitogen-activated kinase or Jun kinase. Furthermore, activation of the IkappaB-alpha kinases precedes both the appearance of hyperphosphorylated IkappaB-alpha and its subsequent degradation, as well as the translocation of NF-kappaB to the nucleus. Deletion mutagenesis of the IkappaB-alpha polypeptide revealed that these kinases bind in or around the ankyrin repeat domains and phosphorylate residues within the C terminus. These kinases, however, were not identical to casein kinase II and displayed a pharmacologic profile distinct from other known kinases. These kinases may represent components of a signal transduction pathway regulating IkappaB-alpha levels in vascular endothelium.
Bennett
B L
BL
Cell Biology and Inflammation Research, Upjohn Laboratories, Kalamazoo, Michigan 49007, USA.
Lacson
R G
RG
Chen
C C
CC
Cruz
R
R
Wheeler
J S
JS
Kletzien
R F
RF
Tomasselli
A G
AG
Heinrikson
R L
RL
Manning
A M
AM
D017487:Ankyrins / Q000737:chemistry; D001483:Base Sequence; D047390:Casein Kinase II; D002451:Cell Compartmentation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004730:Endothelium, Vascular / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D051550:I-kappa B Kinase; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011994:Recombinant Proteins; D015398:Signal Transduction; D051841:Transcription Factor RelB; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D017487:Ankyrins; D017931:DNA Primers; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D016755:Proto-Oncogene Proteins c-jun; C497593:RELB protein, human; D011994:Recombinant Proteins; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D051841:Transcription Factor RelB; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human