# Gaining a clear view of HIV cell-cell spread using APEX proximity labeling

> **NIH NIH R56** · CASE WESTERN RESERVE UNIVERSITY · 2024 · $515,282

## Abstract

Project Abstract
This project aims to better understand the molecular mechanisms of HIV spread through cell-cell contact
across a virological synapse (VS), a specialized structure formed between HIV infected cells and target cells.
We have developed a novel flow cytometry assay for quantifying and purifying infected cell-target cell pairs.
We have generated infected producer cells that stably express ascorbate peroxidase (APEX) enzymes
localized to different subcellular compartments. Upon addition of hydrogen peroxide and biotin-phenol, APEX
generates short-lived BP radicals that covalently biotinylate proteins and RNAs within a few nanometers of the
enzyme. We will use APEX localized to nucleus, cytoplasm, ER, plasma membrane, and mitochrondria to
provide a robust analysis of how host and viral proteins and RNAs are regulated by VS formation. The
successful completion of this grant will identify determinants of the VS formation and its composition, identify
changes to host cell proteins following VS formation with an emphasis on RNA binding proteins, and determine
how host and viral RNAs are regulated by cell-cell contact.
Aim 1: Identify determinants and composition of virological synapse (VS) formation.
Aim 2: Determine how VS formation affects protein abundance and localization within infected cells, with an
emphasis on cellular RNA binding proteins.
Aim 3: Determine how cell-cell signaling during VS formation impacts the RNA regulatory landscape of
infected cells.

## Key facts

- **NIH application ID:** 11118299
- **Project number:** 1R56AI186612-01
- **Recipient organization:** CASE WESTERN RESERVE UNIVERSITY
- **Principal Investigator:** John Christian Tilton
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $515,282
- **Award type:** 1
- **Project period:** 2024-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11118299

## Citation

> US National Institutes of Health, RePORTER application 11118299, Gaining a clear view of HIV cell-cell spread using APEX proximity labeling (1R56AI186612-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/11118299. Licensed CC0.

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