Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 3'-UTR (untranslated region) of bcl-2 mRNA contains an ARE (AU-rich element) that potentially regulates the stability of bcl-2 mRNA in a cell specific fashion. Previous studies have demonstrated that multiple proteins interact with bcl-2 mRNA in HL-60 (human leukaemia-60) cells, potentially contributing to the overexpression of Bcl-2 protein. Treatment of HL-60 cells with taxol or okadaic acid has been shown to induce destabilization of bcl-2 mRNA, which was associated with decreased binding of trans-acting factors to bcl-2 mRNA. Nucleolin has been identified as one of the bcl-2 mRNA-binding proteins [Sengupta, Bandyopadhyay, Fernandes and Spicer (2004) J. Biol. Chem. 279, 10855-10863]. In an effort to identify additional bcl-2 mRNA-binding proteins, two polypeptides of approx. 45 kDa and 60 kDa were isolated from HL-60 cells by ARE(bcl-2) (transcripts that contain bcl-2 AREs) RNA affinity chromatography. These proteins were identified as the human proliferation associated protein, Ebp1, and human DRBP76 (double stranded RNA-binding protein 76) respectively, by MALDI (matrix-assisted laser-desorption ionization)-MS. RNA electrophoretic mobility shift assays indicated that recombinant Ebp1 binds to ARE(bcl-2) RNA but not to the group 1 ARE present in GM-CSF (granulocyte macrophage-colony stimulating factor) mRNA in vitro. Antibody supershift assays demonstrated that Ebp1 is present in protein-ARE(bcl-2) RNA complexes formed with cytosolic HL-60 extracts. The interaction of Ebp1 with bcl-2 mRNA in HL-60 cells was also demonstrated by RNA co-immunoprecipitation assays. This interaction was not detected in extracts of taxol-treated HL-60 cells. Immunoprecipitation assays further revealed that Ebp1 co-precipitates with nucleolin from HL-60 cytoplasmic extracts. The observation that co-precipitation was decreased when extracts were treated with RNase suggests that Ebp1 and nucleolin are present in the same bcl-2 mRNP (messenger ribonucleoprotein particle) complexes. RNA-decay assays further demonstrated that Ebp1 decreased the rate of decay of beta-globin-ARE(bcl-2) transcripts in HL-60 cell extracts. Collectively, these results indicate a novel function for Ebp1 in contributing to the regulation of bcl-2 expression in HL-60 cells.
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PMID:Identification of Ebp1 as a component of cytoplasmic bcl-2 mRNP (messenger ribonucleoprotein particle) complexes. 1639 31

RNase-L mediates critical cellular functions including antiviral, pro-apoptotic, and tumor suppressive activities; accordingly, its expression must be tightly regulated. Little is known about the control of RNASEL expression; therefore, we examined the potential regulatory role of a conserved 3'-untranslated region (3'-UTR) in its mRNA. The 3'-UTR mediated a potent decrease in the stability of RNase-L mRNA, and of a chimeric beta-globin-3'-UTR reporter mRNA. AU-rich elements (AREs) are cis-acting regulatory regions that modulate mRNA stability. Eight AREs were identified in the RNase-L 3'-UTR, and deletion analysis identified positive and negative regulatory regions associated with distinct AREs. In particular, AREs 7 and 8 served a strong positive regulatory function. HuR is an ARE-binding protein that stabilizes ARE-containing mRNAs, and a predicted HuR binding site was identified in the region comprising AREs 7 and 8. Co-transfection of HuR and RNase-L enhanced RNase-L expression and mRNA stability in a manner that was dependent on this 3'-UTR region. Immunoprecipitation demonstrated that RNase-L mRNA associates with a HuR containing complex in intact cells. Activation of endogenous HuR by cell stress, or during myoblast differentiation, increased RNase-L expression, suggesting that RNase-L mRNA is a physiologic target for HuR. HuR-dependent regulation of RNase-L enhanced its antiviral activity demonstrating the functional significance of this regulation. These findings identify a novel mechanism of RNase-L regulation mediated by its 3'-UTR.
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PMID:Post-transcriptional regulation of RNase-L expression is mediated by the 3'-untranslated region of its mRNA. 1723 28


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