AIMS

Dysfunctional regulation of mitochondrial dynamics, which switches the balance to fission, is involved in neurodegeneration in Parkinson's disease (PD). Dynamin-related protein-1 (Drp1), a key regulator of mitochondrial fission, has been attributed recently to such neurodegeneration in PD. However, the machinery that connects Drp1 to the pathophysiology of PD is unclear.

RESULTS

We demonstrated that nitric oxide (NO) was overproduced on 1-methyl-4-phenylpyridinium ion (MPP) treatment, which subsequently engendered S-nitrosylation of Parkin (SNO-Parkin), and thus decreased the interaction with Drp1, leading to elevated Drp1 expression. Consistent with this, Drp1 was elevated in the ventral midbrain of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated PD mouse models, a region usually affected by PD. Concomitantly, in a mouse model of MPTP-induced PD, both SNO-Parkin and Drp1 levels were increased, whereas no significant difference in SNO-Drp1 protein levels were found in these mice. In addition, NO stress, induced by MPP, triggered the phosphorylation of Drp1 Ser616 and caused its subsequent recruitment to the mitochondria. These events create a death-prone environment that contributes to the loss of dopaminergic neurons.

INNOVATION

We first showed that SNO-Parkin reduced its ability as a suppressor of Drp1 expression, leading to upregulation of Drp1 in neurotoxin-based PD models, in vitro and in vivo.

CONCLUSION

Our results provide a molecular explanation for the contribution of Drp1 to the pathogenesis of sporadic PD. These findings indicate that the SNO-Parkin pathway may be a novel therapeutic target to treat PD. Antioxid. Redox Signal. 25, 609-622.