CD4-Dependent Modulation of HIV-1 Entry by LY6E

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Interferon-inducible genes (ISGs) play complex roles in viral infections, with some promoting and others inhibiting viral replication.
• Lymphocyte antigen 6E (LY6E) is an ISG known to modulate viral infections, including HIV-1, in a cell type-dependent manner.
• Previous studies indicated LY6E promotes HIV-1 infection in high-CD4-expressing cells like PBMCs and SupT1 cells.

Purpose of the Study:

• To investigate the role of LY6E in HIV-1 infection in low-CD4-expressing cells.
• To elucidate the mechanism by which LY6E modulates HIV-1 entry and replication.
• To understand the differential impact of LY6E on HIV-1 pathogenesis based on CD4 expression levels.

Main Methods:

• Studied HIV-1 infection in Jurkat cells and human monocyte-derived macrophages (MDMs) with varying LY6E expression levels.
• Utilized gene knockdown and overexpression techniques for LY6E.
• Assessed CD4 receptor levels and internalization via cell surface staining and microscopy.
• Manipulated CD4 expression and function to confirm its role in LY6E's effects.

Main Results:

• LY6E inhibits HIV-1 entry and replication in low-CD4-expressing Jurkat cells and MDMs.
• Knockdown of LY6E increased HIV-1 infection in these cells, while overexpression inhibited it.
• LY6E downregulates cell surface CD4 by enhancing its internalization, impairing HIV-1 binding.
• Overexpression of CD4 in Jurkat cells rescued LY6E-mediated inhibition, and CD4 blockade in SupT1 cells abolished LY6E enhancement of HIV-1 entry.

Conclusions:

• LY6E exhibits opposing roles in HIV-1 infection, inhibiting it in low-CD4 cells and promoting it in high-CD4 cells.
• The differential effect is mediated by LY6E's modulation of CD4 receptor expression and function.
• These findings highlight the complex roles of ISGs in viral pathogenesis and have implications for understanding HIV-1 infection dynamics.