Zinc activates autophagy by regulating HDAC6 expression following cerebral ischemia/reperfusion injury

Intracellular zinc accumulation and excessive autophagy have been reported to contribute to neuronal death following cerebral ischemia/reperfusion (I/R). Histone deacetylase 6 (HDAC6), which contains a zinc-dependent active site, is closely associated with autophagy. However, the relationship between zinc, HDAC6 and autophagy following cerebral I/R remains unclear. In this study, we aim to investigate whether ischemia-induced zinc accumulation activates autophagy through HDAC6. Rats were treated with zinc chelator, autophagy activator/inhibitor or HDAC6 inhibitor during a 90-minute middle cerebral artery occlusion. Infarct volume, neurological deficits, protein expression, and the colocalization of HDAC6, Beclin1, and zinc in neurons were evaluated. Our results demonstrate that beclin1 expression was significantly increased after cerebral I/R and this elevation was markedly attenuated by zinc chelation. Notably, reactivation of autophagy with rapamycin significantly, though not completely, diminished TPEN-mediated neuroprotection, suggesting that zinc-induced autophagy is an important contributor to neuronal injury following cerebral I/R. Moreover, immunofluorescence revealed that HDAC6 was colocalized with Beclin1 in the penumbra of ischemic rats, and inhibition of HDAC6 reduced Beclin1 expression and alleviated brain injury. Molecular docking analysis suggested a potential interaction between HDAC6 and α-tubulin, which may influence autophagy by regulating microtubule stability and autophagosome transport. Furthermore, chelating zinc decreased HDAC6 expression, while HDAC6 inhibition did not influence zinc levels, demonstrating that zinc acts upstream of HDAC6. In conclusion, our findings identify a novel zinc-HDAC6-autophagy signaling axis underlying neuronal injury following cerebral I/R, suggesting that targeting zinc homeostasis or HDAC6 may represent a promising therapeutic strategy.