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Titolo:
Characterization of a major histocompatibility complex class II X-box-binding protein enhancing tat-induced transcription directed by the human immunodeficiency virus type 1 long terminal repeat
Autore:
Mischiati, C; Feriotto, G; Borgatti, M; Giacomini, P; Gambari, R;
Indirizzi:
Univ Ferrara, Dept Biochem & Mol Biol, I-44100 Ferrara, Italy Univ Ferrara Ferrara Italy I-44100 em & Mol Biol, I-44100 Ferrara, Italy Univ Ferrara, Ctr Biotechnol, I-44100 Ferrara, Italy Univ Ferrara Ferrara Italy I-44100 tr Biotechnol, I-44100 Ferrara, Italy Regina Elena Canc Inst, Immunol Lab, Rome, Italy Regina Elena Canc Inst Rome Italy a Canc Inst, Immunol Lab, Rome, Italy
Titolo Testata:
JOURNAL OF VIROLOGY
fascicolo: 19, volume: 74, anno: 2000,
pagine: 8989 - 9001
SICI:
0022-538X(200010)74:19<8989:COAMHC>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIV-1 TAT; GENE-EXPRESSION; IN-VITRO; PROCESSIVITY FACTOR; HLA-DRA; ELONGATION; INITIATION; SEQUENCES; PROMOTER; TRANSACTIVATOR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
45
Recensione:
Indirizzi per estratti:
Indirizzo: Mischiati, C Univ Ferrara, Dept Biochem & Mol Biol, Via Luigi Borsari 46, I-44100 Ferrara, Italy Univ Ferrara Via Luigi Borsari 46 Ferrara Italy I-44100 taly
Citazione:
C. Mischiati et al., "Characterization of a major histocompatibility complex class II X-box-binding protein enhancing tat-induced transcription directed by the human immunodeficiency virus type 1 long terminal repeat", J VIROLOGY, 74(19), 2000, pp. 8989-9001

Abstract

The X-box element present within the promoter region of genes belonging tothe major histocompatibility complex (MHC) plays a pivotal role in the expression of class II molecules, since it contains the binding sites for several well-characterized transcription factors. We have analyzed a randomly selected compilation of viral genomes for the presence of elements homologous to the X box of the HLA-DRA gene. We found that human immunodeficiency virus type 1 (HIV-1) shows the highest frequency of X-like box elements per 1,000 bases of genome. Within the HIV-1 genome, we found an X-like motif in the TAR region of the HIV-1 long terminal repeat (LTR), a regulative regionplaying a pivotal role in Tat-induced HIV-1 transcription. The use of a decoy approach for nuclear proteins binding to this element, namely, XMAS (X like motif activator sequence), performed by transfection of multiple copies of this sequence into cells carrying an integrated LTR-chloramphenicol acetyltransferase construct, suggests that this element binds to nuclear proteins that enhance Tat-induced transcription. In this report we have characterized two proteins, one binding to the XMAS motif and the other to the flanking regions of XMAS. Mobility shift assays performed on crude nuclear extracts or enriched fractions suggest that similar proteins bind to XMAS fromHIV-1 and the X box of the HLA-DRA gene. Furthermore, a UV cross-linking assay suggests that one protein of 37 kDa, termed FAX (factor associated with XMAS)-1, binds to the XMAS of HIV-1. The other protein of 56 kDa was termed FAX-2. In a decoy ex vivo experiment, it was found that sequences recognizing both proteins are required to inhibit Tat-induced HIV-1 LTR-driven transcription. Taken together, the data reported in this paper suggest that XMAS and nearby sequences modulate Tat-induced HIV-1 transcription by binding to the X-box-binding proteins FAX-1 and FAX-2. The sequence homology between XMAS and X box is reflected in binding of a common protein, FAX-1, and similar functional roles in gene expression. To our knowledge, this is the first report showing that transcription factors binding to the X box: of the MHC class II genes enhance the transcription of HIV-1.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/07/20 alle ore 22:54:07