Absolute dependence on kappa B responsive elements for initiation and Tat-mediated amplification of HIV transcription in blood CD4 T lymphocytes

EMBO J. 1995 Apr 3;14(7):1552-60.

Abstract

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)

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • CD4-Positive T-Lymphocytes / physiology
  • CD4-Positive T-Lymphocytes / virology*
  • Cell Line, Transformed
  • Cells, Cultured
  • DNA, Viral / biosynthesis
  • Enhancer Elements, Genetic
  • Gene Expression Regulation, Viral*
  • Gene Products, tat / biosynthesis
  • Gene Products, tat / metabolism*
  • HIV / genetics*
  • HIV / metabolism*
  • Humans
  • Kinetics
  • Molecular Sequence Data
  • NF-kappa B / metabolism*
  • Proviruses / genetics
  • Proviruses / physiology
  • RNA, Messenger / biosynthesis
  • RNA, Viral / biosynthesis
  • Signal Transduction
  • T-Lymphocytes / physiology
  • T-Lymphocytes / virology*
  • Transcription, Genetic
  • Transfection
  • tat Gene Products, Human Immunodeficiency Virus

Substances

  • DNA, Viral
  • Gene Products, tat
  • NF-kappa B
  • RNA, Messenger
  • RNA, Viral
  • tat Gene Products, Human Immunodeficiency Virus