Tubulin hyperacetylation drives HMGB1 nuclear exit via the ROS-PARP1 axis, leading to rotenone-induced G2/M arrest.

Rotenone, a lipophilic pesticide, is strongly linked to dopaminergic neuronal loss, primarily through the inhibition of mitochondrial complex I. Beyond its well-characterized neurotoxic effects, rotenone also triggers G2/M arrest in cells, but the molecular mechanisms linking this cell cycle perturbation to neurodegeneration remain unclear. Here, we identify HMGB1 as a key player in this process. HMGB1, known for its roles in genomic integrity and inflammation, exits the nucleus during rotenone-induced G2/M arrest, whereas its nuclear retention protects against mitotic DNA damage and subsequent cell cycle arrest. We found that rotenone-induced tubulin hyperacetylation precedes HMGB1 nuclear exit and is associated with increased mitochondrial ROS (mtROS) levels. Notably, reducing the levels of αTAT1 (alpha-tubulin acetyltransferase 1) lowers mtROS production, thereby preventing HMGB1 nuclear exit and subsequent rotenone-induced G2/M arrest. Although ROS is known to enhance tubulin acetylation, our findings reveal a bidirectional relationship in which tubulin acetylation regulates mtROS production and exacerbates cellular oxidative stress. Moreover, the PARP1 inhibitor PJ34 suppresses HMGB1 nuclear exit and rescues G2/M arrest, suggesting that mtROS-induced DNA damage elevates PARP1 activity, driving HMGB1 PARylation and subsequent translocation, thus impairing DNA damage repair. Together, our findings uncover a previously unknown tubulin acetylation/mtROS/HMGB1 axis as a key driver of rotenone-induced G2/M arrest, highlighting the essential role of nuclear HMGB1 in maintaining genomic stability. Given that dopaminergic neurons in post-mortem PD brains exhibit G2/M arrest suggestive of abortive cell cycle re-entry, targeting this dysregulated axis may offer a promising strategy to mitigate rotenone-induced neurotoxicity.