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M9480486.TXT
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1994-08-20
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Document 0486
DOCN M9480486
TI Transcriptional suppression of the human T-cell leukemia virus type I
long terminal repeat occurs by an unconventional interaction of a CREB
factor with the R region.
DT 9410
AU Xu X; Brown DA; Kitajima I; Bilakovics J; Fey LW; Nerenberg MI;
Department of Neuropharmacology, Scripps Research Institute, La; Jolla,
California 92037.
SO Mol Cell Biol. 1994 Aug;14(8):5371-83. Unique Identifier : AIDSLINE
MED/94309657
AB To analyze regulation of the human T-cell leukemia virus type I (HTLV-I)
long terminal repeat (LTR), cell lines were generated from LTR-tax x
LTR-beta-galactosidase (beta-Gal) doubly transgenic mouse fibroblastic
tumors. The HTLV-I LTR directs expression of both the tax and lacZ
genes, and Tax up-modulates both promoters in primary cells. However,
once cells were transformed by tax, beta-Gal but not tax expression was
suppressed. Supertransformation of these cells with v-src suppressed
both beta-Gal and tax expression. This suppression was reversed by
treatment with the tyrosine kinase inhibitor herbimycin A or protein
kinase A inhibitor H8. Electrophoretic mobility shift assays
demonstrated augmented binding in the R but not U3 region. This binding
was competitively inhibited by a high-affinity CREB oligodeoxynucleotide
and super-shifted with a specific CREB antibody. Treatment of cells with
the cyclic AMP analog dibutyryl cyclic AMP also transiently increased
the R region binding dramatically. In vitro DNase I footprint analysis
identified a protein-binding sequence in the R region which corresponded
with suppression. However, this target sequence lacked a conventional
CREB-binding site. A 70.5-kDa DNA-binding protein was partially purified
by affinity chromatography, along with a 49-kDa protein which reacted
with CREB-specific sera. These data demonstrate that HTLV-I LTR
suppression is associated with CREB factor binding in the R region,
probably by direct interaction with a 70.5-kDa protein, and provide a
novel mechanism for maintenance of viral latency.
DE Animal Base Sequence Binding Sites Cyclic AMP-Dependent Protein
Kinases/METABOLISM DNA-Binding Protein, Cyclic
AMP-Responsive/*METABOLISM DNA-Binding Proteins/METABOLISM *Gene
Expression Regulation, Viral Genes, pX Genes, src HTLV-I/*GENETICS
Mice Mice, Transgenic Molecular Sequence Data Nuclear
Proteins/METABOLISM *Repetitive Sequences, Nucleic Acid RNA,
Messenger/GENETICS Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.
Transcription, Genetic JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).