Document 0283
 DOCN  M9590283
 TI    Mechanism of CD4 and IL-2 receptor down-regulation by NEF.
 DT    9509
 AU    Allen KM; Greenway AL; McPhee DA; Aids Cellular Biology Unit, National
       Centre for Medical Research,; Fairfield, Victoria, Australia.
 SO    Annu Conf Australas Soc HIV Med. 1994 Nov 3-6;6:239 (unnumbered poster).
       Unique Identifier : AIDSLINE ASHM6/95291816
 AB    Human Immunodeficiency Virus (HIV) is a complex retrovirus that contains
       several structural proteins encoded by gag, pol and env, and at least
       seven auxiliary proteins derived from tat, nef, rev, vif, vpu, vpr and
       tev. The functions of several of these proteins have been clearly
       defined, whereas others such as the nef gene product (Nef) are less well
       understood. Recently our laboratory has investigated the effect of Nef
       on host cell factors by introducing Nef protein directly into cells by
       electroporation. A 27kDa isoform of Nef produced in E. coli by
       translation from the first start codon of HIV-1 nef clone pNL4-3 when
       directly inserted into cells causes down-regulation of cell surface CD4
       and IL-2 receptor (IL2-R) expression without affecting a variety of
       other cell surface molecules such as CD2, CD7 or transferrin receptor.
       In contrast a second isoform of Nef of 25kDa produced in E. coli by
       translation from the second start codon and missing the first 19 amino
       acid residues from the N-terminus had no effect on surface CD4 and
       IL2-R. This data shows that Nef decreases the surface expression of two
       cell surface receptors crucial for antigen recognition of MHC class II
       antigens and for cell proliferation. The exact mechanism of receptor
       down-regulation by Nef is currently unknown. Investigations to delineate
       whether the down regulatory effect of Nef is a transcriptional or
       post-transcriptional event are presently underway in our laboratory.
       After electroporation of CD4+ T-cell lines with highly purified
       recombinant Nef 27, Nef 25 and as a control with
       glutathionine-S-transferase the cells are cultured for up to 24 hours at
       37 degrees C. Following this incubation the cells were harvested and
       total RNA isolated. This was then analysed for relative levels of mRNA
       specific for CD4 and IL2-R by Northern hybridisation. Results are
       discussed within.
 DE    Antigens, CD4/*GENETICS  Cell Line  Cell Transformation, Viral/GENETICS
       Down-Regulation (Physiology)/GENETICS  Gene Expression Regulation,
       Viral/PHYSIOLOGY  Genes, nef/*GENETICS  Human  HIV/*GENETICS  Lymphocyte
       Transformation/GENETICS  Receptors, Interleukin-2/*GENETICS  RNA,
       Messenger/GENETICS  T-Lymphocytes/IMMUNOLOGY/VIROLOGY  MEETING ABSTRACT

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