Human immunodeficiency virus 1 envelope-initiated G2-phase programmed cell death

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• The precise mechanism of human immunodeficiency virus (HIV)-induced T cell death remains elusive despite extensive research.
• HIV-1 infection begins with the binding of the viral envelope glycoprotein (gp120) to the CD4 receptor on T cells.
• Cellular demise is a late-stage event linked to the fusogenic properties of HIV envelope glycoproteins gp120 and gp41.

Purpose of the Study:

• To investigate the molecular mechanisms underlying HIV-induced T cell death.
• To identify specific cell cycle regulatory protein alterations during HIV infection.
• To correlate observed cellular changes with known cytotoxicity pathways.

Main Methods:

• Examined cell cycle regulatory proteins in T cells following cell-cell contact with HIV-1 envelope glycoproteins.
• Utilized in vitro infection models with pathogenic primary HIV-1 isolates.
• Observed cellular morphology and culture disappearance patterns.

Main Results:

• HIV-1 envelope glycoproteins induce cell cycle arrest at the G2 phase.
• Accumulation of cyclin B protein and hyperphosphorylated p34cdc2 (cdk1) kinase observed in affected cells.
• Cells exhibit ballooned morphology, continued cyclin B synthesis, and disappear, mimicking cytotoxicity induced by S phase inhibitors.
• Similar cytopathic effects were noted in peripheral blood mononuclear cells infected with primary HIV-1 isolates.

Conclusions:

• HIV-1 envelope glycoproteins play a critical role in initiating T cell cycle dysregulation and subsequent cell death.
• The observed G2 cell cycle arrest and characteristic cell death pattern provide a novel mechanistic insight into HIV pathogenesis.
• These findings highlight the potential for targeting cell cycle regulatory pathways to mitigate HIV-induced T cell loss.