Cerebral ischemia drives dynamic accumulation of G-quadruplex (G4) DNA structures within microglia — the brain's resident immune cells — and this accumulation correlates with suppressed autophagy through a mTOR-ULK1 signaling cascade. Using both a transient middle cerebral artery occlusion mouse model and oxygen-glucose deprivation in primary microglia, pharmacological G4 stabilization via pyridostatin (Pds) elevated mTOR phosphorylation, increased inhibitory ULK1 phosphorylation, reduced the LC3-II/LC3-I autophagy flux ratio, and caused p62 accumulation alongside Beclin-1 downregulation. Prophylactic Pds treatment produced larger infarct volumes and worse neurological deficits; rapamycin partially reversed these autophagy-related deficits and improved outcomes without full normalization.
This work opens a genuinely underexplored mechanistic corridor. G4 structures have been studied in cancer and telomere biology, but their role in acute neuroinflammation is largely uncharted territory. The finding that a pre-ischemic G4-stabilized microglial state worsens stroke damage reframes G4 dynamics as potential real-time sensors coupling genomic stress to cellular housekeeping programs. The mTOR-autophagy axis in stroke is well established, but linking it upstream to non-canonical DNA conformation is paradigm-shifting in concept, even if confirmation requires human tissue validation. Key limitations: the prophylactic Pds paradigm has limited clinical relevance since patients cannot be pre-treated before stroke onset; all data are murine; and rapamycin's incomplete rescue suggests additional G4-mediated mechanisms beyond autophagy remain unresolved. Incremental translation is years away, but the G4-mTOR-autophagy axis merits serious mechanistic follow-up.
