Identification of a novel RING finger protein as a coregulator in steroid receptor-mediated gene transcription.
Using the DNA-binding domain of androgen receptor (AR) as a bait in a yeast two-hybrid screening, we have identified a small nuclear RING finger protein, termed SNURF, that interacts with AR in a hormone-dependent fashion in both yeast and mammalian cells. Physical interaction between AR and SNURF was demonstrated by ... coimmunoprecipitation from cell extracts and by protein-protein affinity chromatography. Rat SNURF is a highly hydrophilic protein consisting of 194 amino acid residues and comprising a consensus C3HC4 zinc finger (RING) structure in the C-terminal region and a bipartite nuclear localization signal near the N terminus. Immunohistochemical experiments indicated that SNURF is a nuclear protein. SNURF mRNA is expressed in a variety of human and rat tissues. Overexpression of SNURF in cultured mammalian cells enhanced not only androgen, glucocorticoid, and progesterone receptor-dependent transactivation but also basal transcription from steroid-regulated promoters. Mutation of two of the potential Zn2+ coordinating cysteines to serines in the RING finger completely abolished the ability of SNURF to enhance basal transcription, whereas its ability to activate steroid receptor-dependent transcription was maintained, suggesting that there are separate domains in SNURF that mediate interactions with different regulatory factors. SNURF is capable of interacting in vitro with the TATA-binding protein, and the RING finger domain is needed for this interaction. Collectively, we have identified and characterized a ubiquitously expressed RING finger protein, SNURF, that may function as a bridging factor and regulate steroid receptor-dependent transcription by a mechanism different from those of previously identified coactivator or integrator proteins.
Mesh Terms:
Amino Acid Sequence, Animals, CHO Cells, COS Cells, Cell Line, Cloning, Molecular, Cricetinae, Gene Expression Regulation, Gene Library, Hela Cells, Humans, Male, Mice, Molecular Sequence Data, Nuclear Proteins, Rats, Receptors, Androgen, Recombinant Fusion Proteins, TATA Box, Testis, Transcription Factors, Transcription, Genetic, Transcriptional Activation, Transfection, Zinc Fingers
Amino Acid Sequence, Animals, CHO Cells, COS Cells, Cell Line, Cloning, Molecular, Cricetinae, Gene Expression Regulation, Gene Library, Hela Cells, Humans, Male, Mice, Molecular Sequence Data, Nuclear Proteins, Rats, Receptors, Androgen, Recombinant Fusion Proteins, TATA Box, Testis, Transcription Factors, Transcription, Genetic, Transcriptional Activation, Transfection, Zinc Fingers
Mol. Cell. Biol.
Date: Sep. 01, 1998
PubMed ID: 9710597
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