2'3'-cGAMP (sodium salt): High-Affinity STING Agonist for Innate Immunity Research

Executive Summary: 2'3'-cGAMP (sodium salt) is an endogenous cyclic dinucleotide produced by mammalian cGAS upon sensing cytosolic dsDNA, directly activating STING and type I interferon pathways with a binding affinity (Kd) of 3.79 nM (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9). This molecule is highly water-soluble (≥7.56 mg/mL) but insoluble in ethanol and DMSO. APExBIO's B8362 kit provides rigorously characterized 2'3'-cGAMP (sodium salt) for reproducible results in immunology and translational research. Recent studies confirm its centrality in cGAS-STING pathway dissection, particularly in models of neuroinflammation and cancer immunotherapy. High-dose vitamin C and DNase I modulate the cGAS-STING axis, but cGAMP can reverse DNase I–mediated pathway repression, validating its use as a benchmark agonist.

Biological Rationale

2'3'-cGAMP (cyclic [G(2',5')pA(3',5')p]; sodium salt) is an endogenous second messenger in mammalian innate immunity. It is synthesized by cyclic GMP-AMP synthase (cGAS) upon detection of cytosolic double-stranded DNA (dsDNA), a hallmark of infection or cellular damage. Recognition of dsDNA triggers cGAS to catalyze the formation of 2'3'-cGAMP, which then functions as a direct ligand for stimulator of interferon genes (STING). This activation initiates a signaling cascade resulting in phosphorylation of TBK1 and IRF3, ultimately leading to robust production of type I interferons such as IFN-β (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9).

The cGAS-STING pathway is a central component of the vertebrate antiviral and anticancer response. Aberrant activation or suppression of this pathway is implicated in autoimmune diseases, neuroinflammation, cancer, and responses to viral infection. 2'3'-cGAMP (sodium salt) serves as both a physiological activator and an experimental tool to probe this pathway's function and therapeutic potential. Its high specificity and water solubility support its widespread application in cell-based and in vivo studies.

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

2'3'-cGAMP (sodium salt) binds to the STING protein located on the endoplasmic reticulum membrane. Upon binding (Kd = 3.79 nM), STING undergoes conformational changes, translocating to the Golgi and recruiting the kinase TBK1. TBK1 phosphorylates IRF3, leading to its dimerization and nuclear translocation. In the nucleus, IRF3 activates transcription of type I interferon genes, including IFN-β. This process establishes an antiviral and immunostimulatory state in affected cells.

Experimental addition of 2'3'-cGAMP (sodium salt), such as with the APExBIO B8362 kit, can recapitulate endogenous STING activation. This makes it invaluable for dissecting the kinetics, cell-type specificity, and modulation of the cGAS-STING axis in models of inflammation, surgical brain injury, and cancer immunotherapy (2'3'-cGAMP (sodium salt) product page).

Evidence & Benchmarks

• 2'3'-cGAMP (sodium salt) activates STING with a dissociation constant (Kd) of 3.79 nM at physiological temperature (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9).
• In surgical brain injury models, 2'3'-cGAMP reverses DNase I–mediated inhibition of cGAS-STING activation, validating its role as a pathway agonist (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9).
• Water solubility is ≥7.56 mg/mL at room temperature, enabling high-concentration in vitro assays (APExBIO technical specifications).
• 2'3'-cGAMP (sodium salt) is insoluble in ethanol or DMSO—requiring aqueous buffers for preparation (APExBIO datasheet).
• Mouse and rat models confirm that exogenous 2'3'-cGAMP induces microglia activation, neuroinflammation, and type I IFN production, establishing its use in translational neuroscience (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9).

For comparison with related research tools, see this article, which describes 2'3'-cGAMP's selectivity; the current dossier provides updated benchmarking data in disease models. Similarly, this review covers cGAMP's effect on cell migration, which is expanded here with evidence from neuroinflammation. For methodological deep-dives, see this discussion; the present article clarifies translational endpoints.

Applications, Limits & Misconceptions

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

• Dissecting STING-mediated innate immune responses in primary cells, tissues, and animal models.
• Screening and benchmarking STING-targeted compounds and immunotherapeutics.
• Modeling neuroinflammation, particularly in surgical brain injury, where exogenous cGAMP modulates microglia and inflammatory cytokines (Cellular and Molecular Neurobiology, 2024, https://doi.org/10.1007/s10571-024-01470-9).
• Enabling mechanistic studies of antiviral innate immunity and cancer immunotherapy (APExBIO datasheet).

Common Pitfalls or Misconceptions

• 2'3'-cGAMP (sodium salt) will not activate STING in cell lines lacking functional STING expression.
• It does not substitute for upstream DNA sensing; it bypasses cGAS and is ineffective for studying cGAS-specific defects.
• Solubility is limited to aqueous buffers; attempted dissolution in DMSO or ethanol results in precipitation and loss of activity.
• Overstimulation of STING can induce excessive inflammation or cytotoxicity; dose must be empirically optimized.
• Not all preclinical models recapitulate human STING pharmacodynamics—species-specific differences exist.

Workflow Integration & Parameters

For experimental use, APExBIO's 2'3'-cGAMP (sodium salt) (SKU: B8362) is provided as a chemically defined solid (C20H22N10Na2O13P2, MW 718.37). Prepare stock solutions in sterile water at concentrations up to 7.56 mg/mL. Avoid using organic solvents. Store reconstituted aliquots at -20°C for maximal stability. Dosing regimens in cellular assays typically range from 0.1 to 10 μM, with titration required for specific model systems.

In translational studies, 2'3'-cGAMP (sodium salt) enables pathway activation without genetic manipulation. It is compatible with high-throughput screening formats and mechanistic dissection workflows. For further discussion on workflow design and interpretation, see this article, which focuses on cancer immunotherapy; the present review adds neuroinflammation evidence and technical parameters.

Conclusion & Outlook

2'3'-cGAMP (sodium salt) is the benchmark STING agonist, offering unmatched specificity and reproducibility for dissecting cGAS-STING signaling in immunity and disease. Its role in modulating neuroinflammation, as demonstrated in surgical brain injury models, underscores its translational potential. As new immunotherapeutic strategies emerge, APExBIO's validated compound remains an essential tool for mechanistic and therapeutic research (see here for further translational context; this article adds up-to-date in vivo benchmarks). Future work will refine dosing, delivery, and combination strategies in both cancer and infectious disease contexts.