2'3'-cGAMP (sodium salt): Reference STING Agonist for Innate Immunity

Executive Summary: 2'3'-cGAMP (sodium salt) is an endogenous cyclic dinucleotide generated by cGAS upon sensing cytosolic double-stranded DNA [APExBIO]. It binds to the STING protein with nanomolar affinity (Kd = 3.79 nM), surpassing other cyclic dinucleotides [Chini et al., 2025]. Upon binding, it robustly induces type I interferon (IFN-β) via TBK1/IRF3 activation. This compound is widely used in research on innate immune signaling, cancer immunotherapy, and antiviral responses. 2'3'-cGAMP (sodium salt) is a chemically defined, highly soluble molecule, stable at -20°C, and available from APExBIO as SKU B8362.

Biological Rationale

2'3'-cGAMP (sodium salt) is an endogenous second messenger produced in mammalian cells by cyclic GMP-AMP synthase (cGAS). cGAS becomes activated upon detection of cytosolic double-stranded DNA, which can result from viral infection, cellular damage, or mitochondrial DNA leakage [Chini et al., 2025]. The cGAS-STING pathway is a central axis in innate immune surveillance. Activation of this pathway results in transcriptional upregulation of type I interferons and other antiviral genes. Dysregulation of cGAS-STING signaling is implicated in inflammatory diseases, cancer, and age-related pathologies. Chronic NAD depletion, as shown in fibroblast models, triggers mitochondrial DNA leakage and cGAS-STING-dependent interferon responses [Chini et al., 2025]. Thus, 2'3'-cGAMP (sodium salt) is a critical reagent for modeling and dissecting these processes in vitro and in vivo.

Mechanism of Action of 2'3'-cGAMP (sodium salt)

2'3'-cGAMP (sodium salt) is synthesized in cells by cGAS using ATP and GTP as substrates. The product, adenylyl-(3'→5')-2'-guanylic acid (cyclic), forms a unique 2'-5', 3'-5' phosphodiester linkage [APExBIO]. Once formed, 2'3'-cGAMP diffuses to the endoplasmic reticulum where it binds directly to STING (stimulator of interferon genes). This binding induces a conformational change in STING, promoting its trafficking and recruitment of TBK1 kinase. TBK1 phosphorylates IRF3, which then translocates to the nucleus and initiates transcription of IFN-β and other interferon-stimulated genes. This cascade is essential for effective antiviral and antitumor immunity [Chini et al., 2025]. 2'3'-cGAMP displays much higher affinity for mammalian STING compared to bacterial cyclic dinucleotides, making it a precise agonist for mammalian systems [Site Article].

Evidence & Benchmarks

• 2'3'-cGAMP directly activates the STING pathway, resulting in robust type I interferon induction in multiple mammalian cell types (NIH3T3, IMR90, HS5) (Chini et al., 2025).
• The affinity of 2'3'-cGAMP for human STING is Kd = 3.79 nM, higher than canonical bacterial CDNs (APExBIO).
• Chronic NAD depletion triggers VDAC1-mediated mitochondrial DNA leakage, activating cGAS and generating 2'3'-cGAMP, which is required for interferon signaling in this context (Chini et al., 2025).
• Pharmacological inhibition of STING or VDAC1 oligomerization abrogates the interferon response induced by endogenous 2'3'-cGAMP (Chini et al., 2025).
• 2'3'-cGAMP (sodium salt) is water-soluble at ≥7.56 mg/mL but insoluble in ethanol and DMSO, enabling high-concentration aqueous applications (APExBIO).
• For in vitro use, the compound remains stable when stored at -20°C and protected from repeated freeze-thaw cycles (APExBIO).

This article extends the benchmarking focus of "2'3'-cGAMP (sodium salt): Benchmarking the Gold Standard ..." by integrating recent mechanistic findings and translational insights, addressing both molecular benchmarks and workflow integration. For additional systems-level context, see "2'3'-cGAMP (sodium salt): Systems Immunology and Translat...", which discusses how this agonist enables multi-scale modeling; this article clarifies specific use-cases and parameterization. For the latest on translational design, "Beyond Canonical Pathways: Harnessing 2'3'-cGAMP (Sodium ...)" explores clinical applications, while this article emphasizes validated laboratory workflows and pitfalls.

Applications, Limits & Misconceptions

2'3'-cGAMP (sodium salt) is used in:

• Dissecting cGAS-STING pathway activation in immunology and inflammation research.
• Modeling interferon responses in cancer biology and screening of STING-targeted therapeutics.
• Investigating mechanisms of antiviral innate immunity and mitochondrial DNA-driven inflammation.
• In vivo studies of tumor immunogenicity and vaccine adjuvant effects.

Common Pitfalls or Misconceptions

• 2'3'-cGAMP (sodium salt) does not activate non-mammalian STING homologs efficiently; species specificity must be considered [Chini et al., 2025].
• It is ineffective if the STING pathway is genetically disrupted downstream (e.g., TBK1, IRF3 knockout models).
• The compound is unstable in repeated freeze-thaw cycles; improper storage reduces activity [APExBIO].
• It is not suitable for applications requiring solubility in organic solvents like DMSO or ethanol.
• 2'3'-cGAMP is not a direct antiviral agent; its effects are mediated by host immune signaling.

Workflow Integration & Parameters

• Prepare 2'3'-cGAMP (sodium salt) in sterile water (≥7.56 mg/mL) immediately before use for maximal potency [APExBIO].
• Recommended storage: -20°C, minimize freeze-thaw cycles.
• Typical in vitro concentrations: 0.1–10 µM, titrated for cell type and endpoint.
• In vivo dosage and delivery route should be optimized per animal model and experimental endpoint.
• Monitor downstream markers (IFNB1, ISGs) by qPCR or ELISA to confirm functional activation.
• Use appropriate negative controls (e.g., STING inhibitors or knockouts) to validate specificity.

Conclusion & Outlook

2'3'-cGAMP (sodium salt) is a validated, high-affinity agonist for mammalian STING, enabling precise dissection of cGAS-STING pathway biology. Its physicochemical stability, solubility in water, and robust biological activity support its use in preclinical immunology, cancer, and antiviral research. As new insights emerge into cGAS-STING signaling in disease, 2'3'-cGAMP (sodium salt) remains essential for mechanistic studies and therapeutic screening. For detailed specifications and ordering, see the APExBIO product page (B8362).