HIV infection leads to drastic declines in CD4 T helper cells, in part through apoptosis of uninfected cells. Apoptosis of uninfected cells may be induced through the expression of Fas ligand on the surface of HIV-infected cells, stimulating the Fas-dependent apoptotic pathway in cells that come in contact with infected cells. The NEF protein expressed by HIV may play induce the expression of Fas-ligand by infected cells. If this is the case, then a question that arises is how infected cells themselves escape Fas-mediated apoptosis. The NEF protein appears to play a role in this process as well. NEF interacts with the ASK1 kinase (apoptosis signal-regulating kinase) involved in apoptotic signaling by TNF and Fas-ligand. Interaction of NEF with ASK1 prevents phosphorylation of downstream MAP kinases and JNK kinases involved in apoptotic signaling.

Contributor: Glenn Croston, PhD

REFERENCES: Xiao X., Screaton G. HIV-I Nef: negative effector of Fas? Nature Immunology 2001 Vol 2(5): pp 384-385