Inhibition of NF-kappa-B cellular function via specific targeting of the I-kappa-B-ubiquitin ligase.
Activation of the transcription factor NF-kappa B is a paradigm for signal transduction through the ubiquitin-proteasome pathway: ubiquitin-dependent degradation of the transcriptional inhibitor I kappa B in response to cell stimulation. A major issue in this context is the nature of the recognition signal and the targeting enzyme involved in the proteolytic process. Here we show that following a stimulus-dependent phosphorylation, and while associated with NF-kappa B, I kappa B is targeted by a specific ubiquitin-ligase via direct recognition of the signal-dependent phosphorylation site; phosphopeptides corresponding to this site specifically inhibit ubiquitin conjugation of I kappa B and its subsequent degradation. The ligase recognition signal is functionally conserved between I kappa B alpha and I kappa B beta, and does not involve the nearby ubiquitination site. Microinjection of the inhibitory peptides into stimulated cells abolished NF-kappa B activation in response to TNF alpha and the consequent expression of E-selectin, an NF-kappa B-dependent cell-adhesion molecule. Inhibition of NF-kappa B function by specific blocking of ubiquitin ligase activity provides a novel approach for intervening in cellular processes via regulation of unique proteolytic events.
Yaron
A
A
Lautenberg Center for Immunology, Hebrew University-Hadassah Medical School, Jerusalem.
Gonen
H
H
Alkalay
I
I
Hatzubai
A
A
Jung
S
S
Beyth
S
S
Mercurio
F
F
Manning
A M
AM
Ciechanover
A
A
Ben-Neriah
Y
Y
D000595:Amino Acid Sequence; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D019040:E-Selectin / Q000096:biosynthesis / Q000235:genetics; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism; D008025:Ligases / Q000037:antagonists & inhibitors* / Q000502:physiology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D010446:Peptide Fragments / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D051841:Transcription Factor RelB; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects*; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*; D014471:Umbilical Veins
D019040:E-Selectin; D009097:Multienzyme Complexes; D016328:NF-kappa B; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; C497593:RELB protein, human; D014157:Transcription Factors; D014452:Ubiquitins; D051841:Transcription Factor RelB; D044767:Ubiquitin-Protein Ligases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008025:Ligases