Association of heterogeneous nuclear ribonucleoprotein A1 and C proteins with reiterated AUUUA sequences

Department of Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756.
Journal of Biological Chemistry (Impact Factor: 4.57). 05/1993; 268(12):8881-7.
Source: PubMed


Post-transcriptional regulatory mechanisms have been shown to play a major role in gene expression in eukaryotic cells. The presence of a reiterated pentamer (AUUUA) in the 3'-untranslated region (UTR) of mRNAs encoding lymphokines, cytokines, transcription factors, and proto-oncogenes has been shown to be associated with rapid turnover and translation attenuation. Cytoplasmic proteins (70, 50, 43, 36, and 25 kDa) capable of specifically binding to RNAs containing these AU-rich sequences were identified in human peripheral blood T lymphocytes. Levels of the 36-kDa protein were markedly increased following transcriptional, but not translational inhibition, a feature recently reported for hnRNP A1, a protein of comparable mass. Antibodies directed against heterogeneous nuclear ribonucleoproteins (hnRNPs) A1 and C immunoprecipitated 36- and 43-kDa proteins that had bound the AUUUA-rich region contained in the 3'-UTR of granulocyte-macrophage colony-stimulating factor mRNA. Recombinant hnRNP A1 was shown to preferentially bind to RNAs containing AUUUA sequences in a specific manner, and displayed comparable patterns to the 36-kDa AU-specific binding proteins following partial proteolysis. These data identify for the first time hnRNP A1 and C as cytoplasmic proteins in human lymphocytes that are capable of specifically associating with reiterated AUUUA sequences present in the 3'-UTR of labile mRNAs. As such, they may play a role as trans-acting factors in the modulation of cytoplasmic mRNA turnover and translation, in addition to their previously characterized roles as pre-mRNA binding proteins involved in nuclear mRNA processing.

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    • "The identity(ies) of the involved trans-acting factors and their mechanism of action is not clear. However, a number of factors capable of binding specifically to AU-rich RNA sequences are known, including TIA1, HNRNPD (formerly known as AUF1), and hnRNPs A1 and C (Hamilton et al. 1993; Zhang et al. 1993; Del Gatto-Konczak et al. 2000). For hnRNP A1, a function in looping out of introns (leading to suppression of intervening splice sites or exons) has been proposed (Blanchette and Chabot 1999; Nasim et al. 2002). "
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    ABSTRACT: Cooperatively acting pairs of cis-regulatory elements play important roles in many biological processes. Here, we describe a statistical approach, compositionally orthogonalized co-occurrence analysis (coCOA) that detects pairs of oligonucleotides that preferentially co-occur in pairs of sequence regions, controlling for correlations between the compositions of the analyzed regions. coCOA identified three clusters of oligonucleotide pairs that frequently co-occur at 5' and 3' ends of human and mouse introns. The largest cluster involved GC-rich sequences at the 5' ends of introns that co-occur and are co-conserved with specific AU-rich sequences near intron 3' ends. These motifs are preferentially conserved when they occur together, as measured by a new co-conservation measure, supporting common in vivo function. These motif pairs are also enriched in introns flanking alternative "cassette" exons, suggesting a role in silencing of intervening exons, and we showed that these motifs can cooperatively silence splicing of an intervening exon in a splicing reporter assay. This approach can be easily generalized to problems beyond RNA splicing.
    Preview · Article · Oct 2008 · Genome Research
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    • "After penetration into living cells, anti-dsDNA may react with two mRNA binding proteins, hnRNP A2 [13] and PGK-1 (this study). In normal T cells, hnRNP A2 and PGK-1 may specifically interact with the reiterated AUUUA sequences in the 3V-UTR of labile mRNAs [37] [39] and enhance the stability of interleukin-2 [38] mRNA. However, the binding of anti-dsDNA with hnRNP A2 might reduce the stability of IL-2 mRNA and inhibit IL-2 production but promote IL-10 production. "
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    • "A number of ARE binding proteins (ARE-bps) have been identified that can interact with AU- and U-rich regions. These include the ELAV protein family members (most important HuR) (14), the ARE/poly-(U)-binding/degradation factor 1 (AUF-1, also named hnRNP D) (15), the heteronuclear ribonucleoprotein A1 (hnRNP A1) (16), the KH-type splicing regulatory protein (KSRP) (17), tristetraprolin (TTP) (18), the T cell-restricted intracellular antigen (TIA)-1 and the TIA-related protein (TIAR) (19,20). "
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