HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 INTERACTION WITH THE MEMBRANE OF CD4(-SHOCK PROTEIN() CELLS INDUCES THE SYNTHESIS AND NUCLEAR TRANSLOCATION OF 70K HEAT)

In the last few years a growing body of experimental evidence has indi cated that the interaction of human immunodeficiency virus type 1 (HIV -1) surface glycoprotein (gp120) with the membrane of CD4(+) cells may deliver negative signals, eventually leading to programmed cell death (apoptosis) of either mature CD4(+) lymphocytes or CD34(+) haematopoi etic progenitor cells, in the absence of cell infection with HIV-1. Ho wever, information on the possible activation of the classical signal transduction pathway through gp120 engagement of cell surface CD4 is c ontradictory. Heat shock proteins (hsp) or 'stress' proteins' are invo lved in protecting cells from the deleterious effects of heat and othe r stresses and perform various cell roles. In mammalian cells there is evidence that hsp70 is involved in the transport of proteins to lysos omes, mitochondria and the nucleus. The results obtained in our study demonstrate that early (3 h) after the exposure of permissive CD4(+) c ells to HIV-1 (or to purified recombinant gp120) a peak of increased s ynthesis and nuclear translocation of a 70K hsp (and possibly other pr oteins) is observed. These data indicate that gp120 possesses the capa city to trigger a cascade of events through a transmembrane signalling activity.