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Absolute dependence on kappa B responsive elements for initiation and Tat‐mediated amplification of HIV transcription in blood CD4 T lymphocytes.
Author(s) -
Alcamí J.,
Laín de Lera T.,
Folgueira L.,
Pedraza M.A.,
Jacqué J.M.,
Bachelerie F.,
Noriega A.R.,
Hay R.T.,
Harrich D.,
Gaynor R.B.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb07141.x
Subject(s) - transactivation , biology , lymphoblast , long terminal repeat , provirus , kappa , microbiology and biotechnology , enhancer , p50 , transcription (linguistics) , virology , transcription factor , cell culture , gene expression , gene , genetics , philosophy , linguistics , genome
The role of NF‐kappa B‐dependent signals in activating the transcriptional activity of the HIV regulatory region (LTR) was analyzed by systematic comparison of HIV LTR activity in human CD4 T cells purified from peripheral blood and a transformed lymphoblastoid T cell line. In normal CD4 T cells we also analyzed the role played by the viral kappa B responsive elements in HIV replication. Analysis of nuclear extracts of resting, normal T lymphocytes revealed the presence of the p50, but not the p65, NF‐kappa B subunit and the induction by phorbol esters of bona fide (p50‐p65) NF‐kappa B complexes. In parallel, we observed clear enhancer‐dependent HIV LTR transactivation comparable in intensity with that observed in lymphoblastoid cells. We show that unstimulated CD4 T lymphocytes offer a cellular environment of very low permissivity to HIV LTR functioning. This was in sharp contrast to the high spontaneous LTR activity observed in lymphoblastoid T cells, where LTR activity was essentially independent of kappa B‐responsive elements. Due to the low basal LTR activity in resting T lymphocytes, NF‐kappa B‐dependent transactivation was a sine qua non event for induction of the HIV LTR. Surprisingly, even the function of HIV Tat in resting CD4 T lymphocytes was found to be absolutely dependent on LTR kappa B responsive elements. The relevance of these observations obtained in transient transfections was confirmed by the incapacity of blood CD4 T lymphocytes infected with an HIV infectious provirus carrying critical point mutations in the kappa B responsive elements to show any detectable transcriptional activity upon cell activation and prolonged culture in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)