Profiling Nucleotide Signalling Pathways and STING Agonist Activity with a Nucleotide Library

Bekere, I.; Oellinger, R.; Schrimpf, M. R.; Rad, R.; de Oliveira Mann, C. C.

doi:10.1101/2025.11.11.687896

Home/Archive/bioRxiv

bioRxiv · 10.1101/2025.11.11.687896

Profiling Nucleotide Signalling Pathways and STING Agonist Activity with a Nucleotide Library

Bekere, I.·Oellinger, R.·Schrimpf, M. R.·Rad, R.·de Oliveira Mann, C. C.

View original source ↗Export metadata ↓

Abstract

Out of context dsDNA is detected by cGAS, which produces the cyclic dinucleotide 2'3'-cGAMP to activate STING and trigger downstream responses including transcriptional reprogramming, cell death and autophagy. STING agonists, among them non-hydrolysable cyclic dinucleotide analogues, are in active development to enhance immune activation in cancer treatment and vaccine adjuvants. Detailed knowledge of STINGs nucleotide preferences is critical for the development of effective therapeutics, yet the full spectrum of cyclic dinucleotides capable of activating STING has not been comprehensively defined. Especially considering the recent diversity of cyclic nucleotides identified across bacteria and invertebrates, the pool of potential STING agonists to be tested has expanded considerably. Here, we systematically dissect STING nucleotide preferences and distinguish STING-dependent from STING-independent nucleotide signaling pathways by treating THP-1 monocytes and pancreatic cancer cells with a nucleotide library. We identify a set of 27 cyclic dinucleotides that induce STING activation to different extents. Our data indicate that STINGs bias toward 2'3'-linked cyclic dinucleotides underlies its ability to also be activated by nucleotides containing purine-pyrimidine hybrids. In addition, we show that STING can be activated by diverse non-hydrolysable c-di-AMP and cGAMP isomers, thereby expanding the opportunities for designing STING agonists for therapeutic applications.

Explore related subjects

immunology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Bekere, I., Oellinger, R., Schrimpf, M. R., Rad, R., de Oliveira Mann, C. C.. 2025-11-13. Profiling Nucleotide Signalling Pathways and STING Agonist Activity with a Nucleotide Library. https://doi.org/10.1101/2025.11.11.687896

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

TFAM Dependent Mitochondrial Fitness Limits CD8⁺ T Cell Immunopathology and Sustains Protective Immunity during Viral Pneumonia

During respiratory virus infection, CD8 T cells kill infected cells and establish antigen-specific memory, but mechanisms regulating these functions remain incompletely understood. Here, we identify mitochondrial transcription factor A (TFAM)-dependent mitochondrial fitness as a regulator of CD8 T cell function during influenza infection. Human CD8 T cells exhibited an age-associated decline in TFAM expression and mitochondrial function. To model this physiologically relevant decline and determine its consequences for antiviral immunity, we generated CD8 T cell-specific TFAM-haploinsufficient mice. TFAM insufficiency disrupted mitochondrial integrity and bioenergetics and increased mitochondrial DNA and oxidative stress. During influenza infection, TFAM-insufficient CD8 T cells exhibited increased cytotoxic and inflammatory activity associated with lung immunopathology without improved viral control. This early phenotype was followed by loss of effector function, diminished antigen-specific responses, reduced protection following adoptive transfer, and impaired heterosubtypic recall immunity. Thus, TFAM-dependent mitochondrial fitness is a cell-intrinsic regulator that limits immunopathology while sustaining recall immunity.

immunology↗

bioRxiv2026

Gasdermin E couples mitochondrial stress to STING-driven neuronal pyroptosis during Chandipura virus encephalitis

Neurotropic RNA viruses are major causes of fatal encephalitis worldwide, yet how infected neurons transition from antiviral defense to inflammatory cell death is not well characterized. Chandipura virus (CHPV), an emerging neurotropic rhabdovirus, causes acute, rapidly progressive encephalitis with high case fatality in children, but the mechanisms underlying its neuropathogenesis remain poorly defined. Here, we demonstrate that CHPV suppresses canonical RNA virus sensing early but subsequently switches to a mitochondria-driven innate immune program that culminates in inflammatory cell death. Early infection of neuronal cells with CHPV was marked by reduced levels of the mitochondrial antiviral adaptor protein, MAVS and attenuation of type I and III interferon responses. As infection progressed, mitochondrial dysfunction promoted accumulation of mtROS, mitochondrial accumulation of cleaved GSDME and cytosolic mtDNA release, triggering STING activation, which coincided with robust neuroinflammation and pyroptotic cell death. Pharmacological inhibition or genetic silencing of STING markedly attenuated inflammatory signaling, prevented pyroptotic membrane rupture and protected neurons from cell death without significantly affecting viral replication. In contrast, GSDME depletion reduced both viral replication and neuronal death. Notably, GSDME depletion markedly attenuated STING phosphorylation, while STING depletion also reduced GSDME activation, revealing functional coupling between these pathways during CHPV-induced neuronal injury. Collectively, our findings identify a mitochondria-GSDME-STING axis linking early immune evasion to neuroinflammation during CHPV infection, revealing a previously unrecognized mechanism of inflammatory neuronal death in viral encephalitis and highlighting STING as a potential therapeutic target in certain CNS viral infections.

immunology↗

bioRxiv2026

Mutanome-guided immunopeptidomics of blood plasma for neoepitope detection in solid tumors is constrained by cfDNA variant calling sensitivity and MS detection limits

Introduction: Neoepitopes form the basis of tumor-specific immune responses. Tissue biopsy, the primary source for neoepitope detection, is limited and invasive. Therefore, we aimed to identify neoepitopes by mutanome-guided immunopeptidomics from plasma of cancer patients. Methods: Mass spectrometry (MS) data analysis of HLA ligands from plasma (n = 4) was guided by patient-specific mutanomes of cell-free DNA (cfDNA) from plasma or tumor genomic DNA (tgDNA) from tissue. Matched tumor tissue and healthy donor plasma served as controls. Neoepitopes were validated with synthetic peptides, and immunogenicity was assessed using IFN-gamma ELISpot and intracellular cytokine staining. Results: Wild-type immunopeptidomes from tissue and plasma overlapped by 58%, with 91% of plasma HLA ligands rediscovered in tissue. 13 out of 15 tumor-associated HLA ligands detected in plasma were rediscovered in the matching tissue. However, no neoepitopes in plasma were identified by immunopeptidomics guided by cfDNA mutanomes, likely reflecting the limited overlap between cfDNA and tgDNA mutanomes (15%). Using the tgDNA mutanome as a complementary reference, two neoepitopes were detected in one patient's plasma, albeit at the MS detection limit. Both neoepitopes were also discovered in tissue, along with three tissue-exclusive neoepitopes. Two tissue-exclusive neoepitopes induced antigen-specific T cell responses in healthy donor PBMCs. Conclusion: In summary, plasma immunopeptidomics enables profiling of HLA ligands from wild-type proteins, including TAAs. In principle, neoepitope detection from plasma at the peptide level is feasible, but tissue remains the gold standard for variant calling and neoepitope identification. Improved detection methods may enable minimally invasive approaches in the future.

immunology↗