Sprouty 2 binds ESCRT-II factor Eap20 and facilitates HIV-1 gag release

Area of Science:

• Cell biology
• Virology
• Molecular mechanisms of viral release

Background:

• The endocytic sorting complexes required for transport (ESCRT) machinery mediates cellular cargo trafficking.
• HIV-1 Gag protein hijacking of the ESCRT pathway for virus-like particle (VLP) release is selective and non-sequential.
• The precise mechanism by which HIV-1 Gag suppresses ESCRT-I interaction with ESCRT-II remains unclear.

Purpose of the Study:

• To elucidate the role of Sprouty 2 (Spry2) in HIV-1 Gag VLP release.
• To investigate how Spry2 modulates the interaction between ESCRT-I and ESCRT-II during VLP formation.
• To identify Spry2 as a potential cellular factor influencing HIV-1 Gag release mechanisms.

Main Methods:

• Assessing VLP release in COS-1 cells with varying Spry2 levels.
• Investigating the binding interaction between Spry2 and the ESCRT-II component Eap20.
• Analyzing the effect of Spry2 on the ESCRT-I/ESCRT-II complex formation.
• Evaluating VLP release upon co-expression of Gag with Spry2 fragments.

Main Results:

• VLP release was dependent on the steady-state levels of Spry2.
• Spry2 directly binds to Eap20, an ESCRT-II component.
• Spry2 binding to Eap20 disrupts the interaction between ESCRT-I and ESCRT-II.
• Co-expression of Gag with an Eap20-binding Spry2 fragment enhanced VLP release.
• Spry2 facilitated the release of Gag mutants lacking Tsg101 binding, dependent on the secondary L domain and Spry2-Eap20 interaction.

Conclusions:

• Sprouty 2 is a novel cellular factor that facilitates HIV-1 Gag VLP release.
• Spry2 acts by disrupting the ESCRT-I and ESCRT-II interaction via Eap20 binding.
• Spry2 plays a role in both primary and secondary HIV-1 Gag L domain-mediated release pathways.