The Double-Edged Sentinel: cGAS-STING as a Context-Dependent Regulator of Microglial Senescence and Neuronal Genotoxic Stress in Neurodegeneration.
Abstract
Background
Neurodegenerative diseases may continue to progress even when a pathogenic protein aggregate is reduced, suggesting that downstream inflammatory and genotoxic circuits can become partly autonomous. This narrative review examines cGAS-STING as a context-dependent regulator of DNA-stress responses in the ageing and proteinopathic brain.
Methods
PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar were searched for mechanistic, translational, and human-tissue studies of cGAS-STING, DNA damage, mitochondrial quality control, neuroinflammation, and major neurodegenerative diseases. Evidence was separated into biochemical or cellular, animal, and human observations, and contradictory findings were retained.
Results
Mitochondrial DNA leakage is a recurrent candidate trigger, while activity-induced nuclear DNA breaks, defective repair, retrotransposon-derived cDNA, and micronuclear rupture provide conditional inputs. Microglial evidence is currently more extensive and causally developed than neuron-specific evidence; neuronal STING is most firmly supported in selected contexts such as excitotoxic or ischemic stress. Across Alzheimer disease, Parkinson disease, ALS/FTD, multiple sclerosis, and Huntington disease, cGAS-STING-associated inflammation is plausible but not uniform, and human validation remains limited. Therapeutic strategies therefore require cell-, source-, and stage-aware modulation rather than indiscriminate pathway ablation.
Conclusion
cGAS-STING is best regarded as a testable kinetic-bottleneck model, not a universal driver of neurodegeneration. Longitudinal human studies and cell-resolved biomarkers are needed to determine when recalibration can suppress pathological inflammation while preserving antiviral and homeostatic functions.