A new member of the I kappaB protein family, I kappaB epsilon, inhibits RelA (p65)-mediated NF-kappaB transcription.

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.
Mesh Terms:
Amino Acid Sequence, Ankyrin Repeat, B-Lymphocytes, Cell Line, Cloning, Molecular, DNA, DNA, Complementary, Epithelial Cells, Gene Expression Regulation, Humans, I-kappa B Proteins, Interleukin-1, Kidney, Molecular Sequence Data, NF-kappa B, NF-kappa B p50 Subunit, NF-kappa B p52 Subunit, Organ Specificity, Protein Binding, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-rel, RNA, Messenger, T-Lymphocytes, Tetradecanoylphorbol Acetate, Transcription Factor RelA, Transcriptional Activation, Tumor Necrosis Factor-alpha
Mol. Cell. Biol.
Date: Oct. 01, 1997
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