Document 0289
 DOCN  M9590289
 TI    HIV-1 NEF associates with host cell proteins involved with cellular
       signalling and activation.
 DT    9509
 AU    Greenway A; Azad A; McPhee D; AIDS Cellular Biology Unit, National
       Centre for Medical Research,; Fairfield, Victoria, Australia.
 SO    Annu Conf Australas Soc HIV Med. 1994 Nov 3-6;6:220 (unnumbered
       abstract). Unique Identifier : AIDSLINE ASHM6/95291810
 AB    HIV-1 Nef protein causes the loss of cell surface CD4 and IL-2 receptor
       (IL-2R) from PBMC and CD4+ T-cell lines. As both CD4 and the IL-2 R play
       critical roles in antigen-driven helper T-cell signalling and T-cell
       proliferation, respectively, the role of Nef in the viral life cycle may
       be to perturb signalling pathways emanating from these receptors.
       However, the intracellular targets for Nef, that result in receptor
       down-regulation are unknown. Using a recombinant
       glutathione-S-transferase-full length Nef (GST-Nef 27) fusion protein,
       produced in E.coli by translation from the first start codon of HIV-1
       nef clone pNL4-3, as an affinity reagent to probe cytoplasmic extracts
       of MT-2 cells and PBMC, we have shown that Nef interacts with at least
       seven protein species ranging from 24 to 75 kDa. Immunoblotting
       identified four of these proteins as p56lck, CD4, p53 and p44mapk/erk1,
       all of which are intimately involved in intracellular signalling. To
       assess the relevance of these interactions and further define the
       biochemical activity of Nef in signal transduction pathways, highly
       purified Nef 27 protein was introduced directly into PBMC by
       electroporation. Nef 27-treated PBMC showed reduced proliferative
       responsiveness to exogenous recombinant IL-2 The src-family kinase
       p56lck is associated with the beta chain of IL-2 receptor and is
       intrinsically involved in signalling following IL-2 engagement of its
       receptor. Normally, stimulation of T-cells by Il-2 or phorbol
       12-myristate 13-acetate provokes augmentation of p56lck activity and
       corresponding post-translational modification of p56lck. These changes
       were also inhibited by treatment of PBMC with Nef, suggesting that Nef
       interferes with activation of p56lck, and as a consequence, of
       signalling via the IL-2 receptor. The effect of HIV-1 Nef on cell
       activation and proliferation may partly be explained by its interaction
       with specific cellular proteins. Interaction of Nef with these proteins
       may modulate their activity such that the cellular response to antigen
       or lymphokines is severely reduced resulting in the profound
       immunodeficiency characteristic of HIV infection.
 DE    Antigens, CD4/*GENETICS  Cell Line  Cell Transformation, Viral/GENETICS
       Genes, nef/*GENETICS  Human  HIV-1/*GENETICS  Lymphocyte
       Transformation/GENETICS  Monocytes/VIROLOGY  Receptors,
       Interleukin-2/*GENETICS  Signal Transduction/*GENETICS
       T-Lymphocytes/VIROLOGY  Virus Activation/*GENETICS  MEETING ABSTRACT

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