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: 4.6). 05/1993; 268(12):8881-7.
Source: PubMed

ABSTRACT 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.

Download full-text


Available from: James S Malter, Jul 07, 2015
  • Source
    [Show abstract] [Hide abstract]
    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.
    Genome Research 10/2008; 18(10):1643-51. DOI:10.1101/gr.080085.108 · 13.85 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent evidence suggests that gene expression may be regulated, at least in part, at post-transcriptional level by factors inducing the extremely rapid degradation of messenger RNAs. These factors include reactions between adenyl-uridyl-rich elements (AREs) of the relevant mRNA and either specific proteins that bind to these elements or exosomes. This review deals with examples of the proteins (AU-rich binding proteins, AUBPs) and exosomes, which have been shown to form complexes with AREs and bring about rapid degradation of the relevant mRNA, and with certain other factors, which protect the RNA from such degradation. The biochemical and physiological factors underlying the stability of messenger RNAs carrying the ARE motifs will be reviewed in the light of their emerging significance for cell physiology, human pathology, and molecular medicine. We also consider the possible application of the results of recent insights into the mechanisms to pharmacological interventions to prevent or cure disorders, especially developmental disorders, which the suppression of gene expression may bring about. Molecular targeting of specific steps in protein degradation by synthetic compounds has already been utilized for the development of pharmacological therapies.
    Journal of Cellular Physiology 06/2003; 195(3):356-72. DOI:10.1002/jcp.10272 · 3.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The mRNAs that encode certain cytokines and proto-oncogenes frequently contain a typical AU-rich motif that is located in their 3'-untranslated region. The protein AUF1 is the first factor identified that binds to AU-rich regions and mediates the fast degradation of the target mRNAs. AUF1 exists as four different isoforms (p37, p40, p42 and p45) that are generated by alternative splicing. The fact that AUF1 does not degrade mRNA itself had led to the suggestion that other AUF1 interacting proteins might be involved in the process of selective mRNA degradation. Here we used the yeast two-hybrid system in order to identify proteins that bind to AUF1. We detected AUF1 itself, as well as the ubiquitin-conjugating enzyme E2I and three RNA binding proteins: NSEP-1, NSAP-1 and IMP-2, as AUF1 interacting proteins. We confirmed all interactions in vitro and mapped the protein domains that are involved in the interaction with AUF1. Gel-shift assays with the recombinant purified proteins suggest that the interacting proteins and AUF1 can bind simultaneously to an AU-rich RNA oligonucleotide. Most interestingly, the AUF1 interacting protein NSEP-1 showed an endoribonuclease activity in vitro. These data suggest the possibility that the identified AUF1 interacting proteins might be involved in the regulation of mRNA stability mediated by AUF1.
    Biological Chemistry 02/2003; 384(1):25-37. DOI:10.1515/BC.2003.004 · 2.69 Impact Factor