Identification of TINO: a new evolutionarily conserved BCL-2 AU-rich element RNA-binding protein.
Modulation of mRNA stability by regulatory cis-acting AU-rich elements (AREs) and ARE-binding proteins is an important posttranscriptional mechanism of gene expression control. We previously demonstrated that the 3'-untranslated region of BCL-2 mRNA contains an ARE that accounts for rapid BCL-2 down-regulation in response to apoptotic stimuli. We also demonstrated that the BCL-2 ARE core interacts with a number of ARE-binding proteins, one of which is AU-rich factor 1/heterogeneous nuclear ribonucleoprotein D, known for its interaction with mRNA elements of others genes. In an attempt to search for other BCL-2 mRNA-binding proteins, we used the yeast RNA three-hybrid system assay and identified a novel human protein that interacts with BCL-2 ARE. We refer to it as TINO. The predicted protein sequence of TINO reveals two amino-terminal heterogeneous nuclear ribonucleoprotein K homology motifs for nucleic acid binding and a carboxyl-terminal RING domain, endowed with a putative E3 ubiquitin-protein ligase activity. In addition the novel protein is evolutionarily conserved; the two following orthologous proteins have been identified with protein-protein BLAST: posterior end mark-3 (PEM-3) of Ciona savignyi and muscle excess protein-3 (MEX-3) of Caenorhabditis elegans. Upon binding, TINO destabilizes a chimeric reporter construct containing the BCL-2 ARE sequence, revealing a negative regulatory action on BCL-2 gene expression at the posttranscriptional level.
Donnini
Martino
M
Department of Experimental Pathology and Oncology, School of Medicine, University of Florence, 50134 Florence, Italy.
Lapucci
Andrea
A
Papucci
Laura
L
Witort
Ewa
E
Jacquier
Alain
A
Brewer
Gary
G
Nicolin
Angelo
A
Capaccioli
Sergio
S
Schiavone
Nicola
N
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D017173:Caenorhabditis elegans; D002460:Cell Line; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000378:metabolism; D019992:Databases as Topic; D015536:Down-Regulation; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D019254:Genes, bcl-2; D006367:HeLa Cells; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000378:metabolism; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D014561:Urochordata
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D018076:DNA, Complementary; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012260:Ribonucleases