From protector to perpetrator: The cGAS-STING pathway at the intersection of neurodegeneration and neuroinflammation¶

The finding¶

This is a review article, not a primary research study — it synthesizes existing literature on how chronic cGAS-STING activation, driven by cytosolic self-DNA (genomic instability, mitochondrial dysfunction, retrotransposons), converts a normally protective innate-immune pathway into a driver of neuroinflammation across ALS/FTD, Alzheimer's, Parkinson's, and Huntington's disease. It maps cell-type-specific consequences in microglia, astrocytes, and neurons, and evaluates emerging cGAS-STING-targeted therapeutics. Notably, the authors also flag a retracted PINK1-Parkin-STING report, urging caution about overinterpreting that specific mechanistic link.

Where it fits¶

This review speaks most directly to ARM 1 (interferon/JAK-STAT), since cGAS-STING sensing of cytosolic DNA and downstream IRF3/7-driven type I IFN is a core upstream input to the tonic IFN signature hypothesized in SAMHD1 A565T carriers. It's also relevant background for ARM 2 (mitochondrial), given its emphasis on mtDNA as an immunogenic trigger and its discussion of PINK1/Parkin-mediated mitophagy — mechanistically adjacent to the ISG15-BECN1 mitophagy block proposed in the SAMHD1 model, though not the same molecule or pathway. For a variant hypothesized to cause chronic, moderate (rather than acute, high) IFN tone, a synthesis of how sustained cGAS-STING signaling reshapes glial and neuronal phenotypes over time is useful context for thinking about potential CNS consequences of chronic SAMHD1-driven interferon exposure — this is conceptual scaffolding, not evidence about SAMHD1 itself.

Caveats¶

This is a narrative review, not new experimental data; it contains no findings specific to SAMHD1, ANKIB1, or VDAC1, and nothing here should be read as evidence about the A565T variant.
The disease contexts discussed (ALS/FTD, AD, PD, HD) involve largely homozygous/biallelic pathway disruptions or aggregation-driven models in mostly rodent or postmortem human tissue — not the heterozygous, partial-loss-of-function, moderate-tone state relevant to SAMHD1 A565T.
The authors themselves highlight contradictory and retracted data (PINK1-Parkin-STING) within the field, underscoring that mitochondrial-DNA-to-STING mechanisms remain unsettled even in well-studied neurodegeneration models.

What to watch¶

The open question this raises for the SAMHD1 program is whether the same CNS-specific microglia/astrocyte cGAS-STING amplification loops described here could be operative — at lower, chronic amplitude — in A565T carriers, and whether JAK inhibition (effective in ARM 1) would be sufficient to interrupt such a loop in neural tissue specifically, given the pathway's partly cell-autonomous, partly non-cell-autonomous character in brain.

Source: From protector to perpetrator: The cGAS-STING pathway at the intersection of neurodegeneration and neuroinflammation — 2026.