# Ubiquitin ligase regulation of tissue-resident T cell and anti-tumor activity

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2023 · $237,000

## Abstract

PROJECT SUMMARY
 In malignancies, CD8+ T cells can recognize and eliminate tumor cells, but often fail to cure disease due
to their progressive loss of antitumor function resulting from chronic activation in the immunosuppressive tumor
microenvironment. In response to infection in healthy tissues, T cells differentiate into tissue-resident memory
cells (TRM), and after clearance of antigen can remain lodged in tissues to survey and provide protection from
reinfection. When TRM-like T cells are found in cancer patient tumors, improved responses to immunotherapy
and better patient outcomes are observed. However, whether TRM-like TIL represent ‘progenitors’ of exhausted
TIL, or are a separate cell state outside the exhaustion spectrum is still unclear.
 To better understand the relationship among TRM-like TIL, exhaustion states, and TRM memory cells, we
directly compared TRM from acute viral infection and exhausted TIL from tumors to find transcriptional differences
between these distinct T cell states. Focusing on genes highly expressed by TRM that may mediate their
enhanced functions in tissues, we asked which of those were downregulated as T cells became terminally
exhausted, coincident with loss of function. This approach identified numerous genes related to protein
regulation, including multiple under-characterized E3 ubiquitin ligases. Protein regulation by the ubiquitin
proteosome system is an essential biological process for homeostasis, crucial for cell differentiation and function,
and has been previously shown to be important for memory T cell identity. Correlated with our preliminary data,
we found that exhausted TIL have an excess of unfolded proteins in their cytosol, and when we enforced
expression of the identified E3 ubiquitin ligases in tumor-specific T cells, it allowed for better tumor control and
improved mouse survival. Therefore, we propose to explore the relationship between protein homeostasis and
TRM, exhaustion, and TRM-like TIL cell fates. Aim 1 seeks to understand if the identified E3 ubiquitin ligases
influence exhaustion or TRM cell fate by using mouse models of cancer to enforce expression or knock out these
ligases and study exhaustion T cell fate, or to enforce expression or knock out the ligases in acute viral infection
and study TRM cell fate. Aim 2 seeks to identify the protein-interaction targets of these E3 ubiquitin ligases by in
vitro BioID proximity labeling assay and mass spectrometry, then verify the targets in vivo TIL and determine if
expression of these ligases in TIL can decrease unfolded protein abundance. Understanding the relationship
between T cell exhaustion and TRM can provide vital new insights into the biology of these two differentiated T
cell populations and inform efforts to manipulate T cell fates towards TRM-like TIL to benefit cancer
immunotherapy.

## Key facts

- **NIH application ID:** 10726015
- **Project number:** 1R21AI178362-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Ananda W Goldrath
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $237,000
- **Award type:** 1
- **Project period:** 2023-07-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10726015

## Citation

> US National Institutes of Health, RePORTER application 10726015, Ubiquitin ligase regulation of tissue-resident T cell and anti-tumor activity (1R21AI178362-01). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10726015. Licensed CC0.

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