# Regulation of immunity by the cGAS-STING pathway

> **NIH NIH R01** · BOSTON CHILDREN'S HOSPITAL · 2024 · $789,339

## Abstract

Project Summary
The goal of this proposal is to dissect the mechanisms of self-DNA detection by the enzyme cyclic GMP-AMP
synthase (cGAS), and to determine the relative contribution of its diverse signaling activities to inflammation in
the microenvironment of implantable murine tumors. cGAS operates in virtually all cell types as a DNA sensory
protein, which synthesizes the second messenger cyclic GMP-AMP (cGAMP) upon binding DNA. This second
messenger stimulates interferon (IFN) and inflammatory activities via the downstream protein STING. Because
cGAS detects the sugar-phosphate backbone of DNA, a major question relates to how this enzyme is regulated
to ensure self-nonself discrimination. This question relates to much fundamental biology and the answer will
impact the increasing number of clinical endeavors that target the cGAS-STING pathway. The cGAS-STING
pathway is oft-discussed in the context of antitumor immunity, but the activities of this pathway that are beneficial
(or not) to immunity remain unclear. For example, inflammatory activities induced by cGAS-STING in the tumor
microenvironment (TME) have been reported to induce protective inflammatory and cytolytic CD8+ T cells. But
cGAS-STING signaling events have also been reported to promote tumor growth and disease progression. A
central idea that drives our work is that the ubiquitous presence of the cGAS-STING pathway in most cell types,
along with its diverse signaling effectors (cGAMP, IFNs, cytokines), can create a complex TME prone to
unpredictable outcomes (e.g. disease resolution or progression). In order to understand each activity of this
pathway, new experimental tools are needed to disentangle its effector functions. Herein, we describe new
synthetic biology-based genetic circuits that can dissect the effector functions of cGAS-STING, within cancer
cells specifically. Notably, these systems led to the discovery of specifies-specific differences in the ability of
primate and murine cGAS proteins to detect self-DNA. This finding raises questions of the suitability of mice
and certain primates as accurate preclinical models for cGAS-STING function, and provide a mandate to define
the mechanisms and consequences of cGAS-mediated self-DNA activities. The work in this proposal is based
on the hypothesis that the cGAMP, IFNs and cytokines induced by the cGAS-STING pathway play differential
roles in tissue inflammation and immunity, and that understanding the role of each of these activities, within
specific cell types, requires a detailed characterization of the mechanisms of self (and nonself) DNA detection.
To address this hypothesis, we propose to determine how distinct intra-tumoral cGAS activities influence
protective T cell immunity (Aim 1). In Aim 2, we propose to determine mechanisms of self-DNA reactivity by
human cGAS through comparative analysis of the human, mouse, chimpanzee and orangutan proteins, each of
which display distinct means of self-DNA reactivity.

## Key facts

- **NIH application ID:** 10886044
- **Project number:** 5R01AI167993-03
- **Recipient organization:** BOSTON CHILDREN'S HOSPITAL
- **Principal Investigator:** JONATHAN C KAGAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $789,339
- **Award type:** 5
- **Project period:** 2022-09-19 → 2027-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10886044

## Citation

> US National Institutes of Health, RePORTER application 10886044, Regulation of immunity by the cGAS-STING pathway (5R01AI167993-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10886044. Licensed CC0.

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