Human immunodeficiency virus type 1 Nef associateswith a cellular serine kinase in T lymphocytes.

Abstract

With T-cell lines constitutively expressing Nef from the SF2 strain of human immunodeficiency virus type 1 (HIV-ls5) in the form of a hybrid CD8-Nef fusion protein or T-cell lines chronically infected with HIV-1sF2, a cellular serine kinase was found that specifically associates with Nef. Proteins of 62 kDa and 72 kDa, which coimmunoprecipitated with Nef, were phosphorylated in in vitro kinase assays. This Nefassociated serine kinase activity was not blocked by inhibitors of protein kinase C or protein kinase A and was lost when Nef was truncated at amino acid 94 or 99. These rmdings present evidence that a serine kinase activity is associated with Nef expressed in human T lymphocytes.

From negative factor to a critical role in virus pathogenesis: the changing fortunes of Nef

“…The physiological significance of this observation remains to be clarified. However, in this context it is interesting to note that a number of investigators have alluded to the cytotoxic or cytostatic effects of Nef observed when attempting to generate stable cell lines constitutively expressing Nef (Murphy el al., 1993;Baur et al, 1994;RyanGraham & Peden, 1995). This effect of Nef has recently been confirmed using two different inducible vector systems (S. J. Cooke, unpublished results).…”

“…The CDS-Nef chimera system was used to demonstrate that Nef coprecipitated with a serine/threonine kinase that phosphorylated two other Nef-binding proteins of molecular mass 62 and 72 kDa (p62 and p72) (Sawai et al, 1994). The identity of these proteins is as yet undefined; however, the study has been extended to show that they interact with amino acid sequences in the central conserved region and also require membrane localization of Nef (Sawai et al, 1995).…”

“…Using filterbinding assays and plasmon resonance it was shown that the Nef proline motif bound to the SH3 domain of Hck with high affinity (K D 250 nM for intact Nef but 300-fold weaker for the , p97, p75, p57, p55, p32, p28, p26 p70, p60, p56, p44, p36, p32, p30, p28, p27 Sawai et al (1994) Harris & Neil (1994) Rossi et al (1996) Harris ( Benichou et al (1994) Harris (1995) isolated PxxP motif) Lee et al, 1995). An additional PxxP motif at amino acids 147-150 was also implicated in the interaction, possibly explaining the decreased affinity of the isolated PxxP motif.…”

“…In an attempt to analyse these effects of Net at the biochemical level, Net was expressed as a fusion with the extracellular and transmembrane regions of CDSe in Jurkat T cells (Baur et al, 1994). Only a small proportion of the chimera was expressed on the cell surface, but when these cells were activated by anti-TCR antibodies the CDS-Nef chimera ~.38~ …”

Using death to one's advantage: HIV modulation of apoptosis

“…Nef associates with cellular serine/threonine kinases (possibly PAK), as well as src-like tyrosine kinases (Hck and Lck). [136][137][138] Both of these types of kinases are important in T cell activation. [136][137][138][139] Consistent with this observation, Fas-L is expressed following activation of the TCR leading to the phosphorylation of these kinases and expression is inhibited by cell treatment with immunosuppressive drugs.…”