Implications of tissue specific STING protein flux and abundance on inflammation and the development of targeted therapeutics
Thomas E. Angel, Zhuo Chen, Ahmed Moghieb, Sze-Ling Ng, Allison M. Beal, Carol Capriotti, Leonard Azzarano, Debra Comroe, Michael Adam, Patrick Moore, Bao Hoang, Kelly Blough, Joanne Kuziw, Joshi M. Ramanjulu, G. Scott Pesiridis
Abstract
Drugs targeting the ER-resident innate immune receptor Stimulator of Interferon Genes (STING) are in development for treatments of cancer and inflammatory diseases. Accurate determination of STING receptor levels in normal and disease tissue is an essential component of modeling pharmacology and drug-target disposition. Using metabolic labeling with deuterium oxide paired with high resolution mass spectrometry, we report the protein fractional synthesis rates and turnover of STING in wild-type (C57BL/6) and inflamed mice carrying the Trex1 D18N mutation (Trex1D18N) as a STING-dependent model of human Acardi-Goutiéres syndrome.
Introduction
To-date there are multiple STING agonist assets in clinical development as a monotherapy or in combination therapy across > 25 human trials in oncology. However, the field has stagnated with less than impressive clinical outcomes. One hypothesis for sub-par efficacy is that the field lacks a quantitative understanding of STING’s protein turnover that dictates dose frequency and receptor activation.
Materials and method
Chemicals and reagents
Recombinant Mouse STING protein (aa 160-371) was purchased from LifeSpan BioSciences (WA, USA). PierceTM IP lysis buffer and SuperBlockTM blocking buffer were purchased from Thermo Scientific (MA, USA). LC/MS solvents including water, acetonitrile, methanol, and formic acid were purchased from Fisher Scientific (MA, USA).
Results
Previous studies demonstrated that STING protein levels, stability and function are regulated by complex mechanisms of ubiquitination that impact STING protein turnover and its ability to facilitate innate immune signaling [47–54]. It is known that activation of STING, either under innate immune stimulatory conditions or by agonist dependent activation, leads to endo-lysosomal ER-to-Golgi (ERGIC) trafficking and nearly complete endolysosomal degradation of STING (Fig 1A) [1].
Discussion
Protein turnover and fractional synthesis rate are dynamic properties of proteins that support drug disposition and pharmacology of disease relevant proteins. With STING-directed therapies in clinical trials, understanding STING’s relative abundance and turnover is critically important to achieving target engagement at the most appropriate dose and frequency. To quantify STING’s protein turnover in a disease-relevant model, we measured the fractional synthesis rates of STING in WT and Trex1D18N mice.
Acknowledgments
We thank Dr. Kate Fitzgerald and Dr. Fiachra Humphries for additional characterizations of the Trex1D18N mice previously published in (12). We also thank Dr. Julia Holter for input on statistics.
Citation: Angel TE, Chen Z, Moghieb A, Ng S-L, Beal AM, Capriotti C, et al. (2025) Implications of tissue specific STING protein flux and abundance on inflammation and the development of targeted therapeutics. PLoS ONE 20(2): e0319216. https://doi.org/10.1371/journal.pone.0319216
Editor: Jon M. Jacobs, Pacific Northwest National Laboratory, UNITED STATES OF AMERICA
Received: April 19, 2024; Accepted: January 28, 2025; Published: February 25, 2025
Copyright: © 2025 Angel et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the manuscript and its Supporting information files.
Funding: The author(s) received no specific funding for this work.
Competing interests: All authors listed are current or former employees of GSK who have owned shares in the past or currently hold shares in GSK plc. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
