title: A new member of the I kappaB protein family, I kappaB epsilon, inhibits RelA (p65)-mediated NF-kappaB transcription.
abstract: A novel member of the I kappaB family has been identified as a protein that associated with the p50 subunit of NF-kappaB in a yeast two-hybrid screen. Similar to previously known I kappaB proteins, this member, I kappaB epsilon, has six consecutive ankyrin repeats. I kappaB epsilon mRNA is widely expressed in different human tissues, with highest levels in spleen, testis, and lung. I kappaB epsilon interacts with different NF-kappaB proteins, including p65 (RelA), c-Rel, p50, and p52, in vitro and in vivo and inhibits the DNA-binding activity of both p50-p65 and p50-c-Rel complexes effectively. Endogenous and transfected NF-kappaB (RelA-dependent) transcriptional activation is inhibited by I kappaB epsilon. I kappaB epsilon mRNA is expressed at different levels in specific cell types and is synthesized constitutively in transformed B-cell lines. It also displays differential induction in response to tumor necrosis factor alpha, interleukin-1, or phorbol ester stimulation compared to I kappaB alpha in non-B-cell lines. Therefore, I kappaB epsilon represents a novel I kappaB family member which provides an alternative mechanism for regulation of NF-kappaB-dependent transcription.
authors.affiliation: Department of Internal Medicine, Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor 48109-0650, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: G J
authors.initials: GJ
authors.lastname: Nabel
mesh_terms: D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D001402:B-Lymphocytes; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004847:Epithelial Cells; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D020672:I-kappa B Proteins; D007375:Interleukin-1 / Q000494:pharmacology; D007668:Kidney / Q000166:cytology; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D052003:NF-kappa B p52 Subunit; D009928:Organ Specificity; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051996:Transcription Factor RelA; D015533:Transcriptional Activation / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D018076:DNA, Complementary; D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D052003:NF-kappa B p52 Subunit; C105627:NFKBIE protein, human; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D004247:DNA; D013755:Tetradecanoylphorbol Acetate