Document 0451
 DOCN  M9460451
 TI    Cis- and trans-regulation of feline immunodeficiency virus:
       identification of functional binding sites in the long terminal repeat.
 DT    9404
 AU    Thompson FJ; Elder J; Neil JC; Department of Veterinary Pathology,
       University of Glasgow,; Bearsden, U.K.
 SO    J Gen Virol. 1994 Mar;75 ( Pt 3):545-54. Unique Identifier : AIDSLINE
       MED/94172327
 AB    Nuclear protein binding sites in the long terminal repeat (LTR) of
       feline immunodeficiency virus (FIV) were identified by the method of
       DNase I footprinting. Using nuclear protein extracts from a feline T
       lymphoma cell line, several discrete footprints were generated upstream
       of the transcriptional initiation site (-50 to -150). The specificity of
       protein binding was examined by competition with oligonucleotides
       representing consensus DNA binding sites for known transcription
       factors. Binding to AP-1 (-124) and ATF (-58) motifs was observed, with
       cross-competition between these sites. A strong footprint signal was
       also detected over a tandemly repeated C/EBP motif (-94, -86) and an
       adjacent weaker footprint was found to be specific for an NF1 motif
       (-72/-63). The effect on FIV LTR promoter activity of progressively
       deleting these nuclear factor binding sites was examined by linking LTR
       deletion mutants to the chloramphenicol acetyltransferase (CAT) gene.
       Deletion of the AP-1 site caused a 10- to 25-fold loss of CAT activity
       whereas deletion past the ATF site reduced activity virtually to
       background levels. The effects of deleting the C/EBP and NF1 sites were
       less marked and varied according to cell type. Transactivation of the
       LTR was assayed using constructs linked to a CAT reporter gene. The
       full-length FIV LTR was not significantly trans-activated. However, the
       expression of a deleted LTR construct lacking the AP-4/AP-1 site but
       retaining C/EBP and ATF sites was partially restored by co-infection
       with FIV or by co-transfection with an infectious molecular clone of FIV
       (FIV-PPR). These results show that host transcription factors responsive
       to cellular activation have a major role in regulating FIV expression,
       and suggest that virus-coded trans-activators acting through U3 may play
       a role in some cellular environments.
 DE    Animal  Base Sequence  Binding Sites/PHYSIOLOGY  Cats  Cell Line
       Chloramphenicol Acetyltransferase/GENETICS/METABOLISM  DNA-Binding
       Proteins/METABOLISM  Gene Deletion  *Gene Expression Regulation, Viral
       Immunodeficiency Virus, Feline/*GENETICS  Molecular Sequence Data
       Protein Binding/PHYSIOLOGY  Repetitive Sequences, Nucleic
       Acid/GENETICS/*PHYSIOLOGY  Support, Non-U.S. Gov't  Support, U.S. Gov't,
       P.H.S.  Trans-Activation (Genetics)/*PHYSIOLOGY  Tumor Cells, Cultured
       JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).