p54(nrb) acts as a transcriptional coactivator for activation function 1 of the human androgen, receptor
ABSTRACT The androgen receptor (AR) has two transactivation functions that have been mapped to the N- and C-terminal domains and designated as activation function-1 (AF-1) and AF-2, respectively. While the molecular basis for AF-2 function has been well studied, little is known about AF-1 coregulators. Therefore, we attempted to identify AF-1-interacting proteins from HEK293 cells by biochemical purification followed by mass fingerprinting by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Purified AF-1 region-interacting proteins were found to contain nuclear RNA-binding protein p54(nrb), polypyrimidine tract-binding protein-associated splicing factor (PSF), paraspeckle protein 1 (PSP1), and PSP2, which are assumed to be involved in pre-mRNA processing. p54(nrb) interacted with AR via the A/B domain in a ligand-dependent manner. Reflecting the physical interaction between p54(nrb) and the AR A/B domain, AR AF-1 function was potentiated by p54(nrb). Our results suggest that p54(nrb) functions as a coactivator of AR that potentiates transcription, and presumably splicing as well.
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ABSTRACT: IbeA is an important invasion determinant contributing to Escherichia coli K1 entry into brain microvascular endothe-lial cells (BMEC) that is a key step in the pathogenesis of E. coli meningitis. Our previous studies have shown that IbeA-induced signaling and E. coli K1 invasion is mediated by two IbeA-binding proteins, vimentin, which is constitu-tively present in the surface of human BMECs (HBMECs), and PSF, which is inducibly expressed in both mesenchymal (endothelium) and non-mesenchymal (epithelium) cells. However, it is unknown whether p54nrb, a PSF partner protein, could contribute to the pathogenesis of E. coli K1 meningitis. Here, we reported that a 54-kDa protein was identified by copurification with PSF through IbeA-affinity chromatography as an IbeA-binding protein, which is identical to p54nrb. Both p54nrb and PSF are RNA-binding proteins and share significant sequence homology. The specific interaction be-tween IbeA and p54nrb was confirmed by Western blot and ligand overlay assays. Recombinant p54nrb blocked E. coli K1 invasion of human BMEC very effectively. Overexpressed p54nrb as a GFP fusion protein in the transfected 293T cells significantly enhanced E. coli K1 invasion. Furthermore, higher levels of surface p54nrb in the transfected 293T cells were detected by flow cytometry. These results suggest that the IbeA invasion protein of E. coli K1 interacts with p54nrb for bacterial invasion of human cells.
RNA 02/2015; 21(3):347-359. DOI:10.1261/rna.045138.114 · 4.62 Impact Factor
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ABSTRACT: This review summarizes the current understanding of the role of nuclear bodies in regulating gene expression. The compartmentalization of cellular processes, such as ribosome biogenesis, RNA processing, cellular response to stress, transcription, modification and assembly of spliceosomal snRNPs, histone gene synthesis and nuclear RNA retention, has significant implications for gene regulation. These functional nuclear domains include the nucleolus, nuclear speckle, nuclear stress body, transcription factory, Cajal body, Gemini of Cajal body, histone locus body and paraspeckle. We herein review the roles of nuclear bodies in regulating gene expression and their relation to human health and disease.Biology 07/2013; 2(3):976-1033. DOI:10.3390/biology2030976