Role of cholesterol in human immunodeficiency virus type 1 envelope protein-mediated fusion with host cells.
In this study we examined the effects of target membrane cholesterol depletion and cytoskeletal changes on human immunodeficiency virus type 1 (HIV-1) Env-mediated membrane fusion by dye redistribution assays. We found that treatment of peripheral blood lymphocytes (PBL) with methyl-beta-cyclodextrin (MbetaCD) or cytochalasin reduced their susceptibility to membrane fusion with cells expressing HIV-1 Env that utilize CXCR4 or CCR5. However, treatment of human osteosarcoma (HOS) cells expressing high levels of CD4 and coreceptors with these agents did not affect their susceptibility to HIV-1 Env-mediated membrane fusion. Removal of cholesterol inhibited stromal cell-derived factor-1alpha- and macrophage inflammatory protein 1beta-induced chemotaxis of both PBL and HOS cells expressing CD4 and coreceptors. The fusion activity as well as the chemotactic activity of PBL was recovered by adding back cholesterol to these cells. Confocal laser scanning microscopy analysis indicated that treatment of lymphocytes with MbetaCD reduced the colocalization of CD4 or of CXCR4 with actin presumably in microvilli. These findings indicate that, although cholesterol is not required for HIV-1 Env-mediated membrane fusion per se, its depletion from cells with relatively low coreceptor densities reduces the capacity of HIV-1 Env to engage coreceptor clusters required to trigger fusion. Furthermore, our results suggest that coreceptor clustering may occur in microvilli that are supported by actin polymerization.
Viard
Mathias
M
Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
Parolini
Isabella
I
Sargiacomo
Massimo
M
Fecchi
Katia
K
Ramoni
Carlo
C
Ablan
Sherimay
S
Ruscetti
Francis W
FW
Wang
Ji Ming
JM
Blumenthal
Robert
R
D015496:CD4-Positive T-Lymphocytes; D002459:Cell Fusion; D002478:Cells, Cultured; D002633:Chemotaxis; D002784:Cholesterol / Q000494:pharmacology*; D003505:Cyclodextrins / Q000494:pharmacology; D003572:Cytochalasins / Q000494:pharmacology; D005434:Flow Cytometry; D015686:Gene Products, env / Q000378:metabolism*; D015497:HIV-1 / Q000472:pathogenicity*; D006801:Humans; D008561:Membrane Fusion / Q000187:drug effects*; D018613:Microscopy, Confocal; D014407:Tumor Cells, Cultured; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D003572:Cytochalasins; D015686:Gene Products, env; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol