YOD1 regulates neuronal mitochondrial unfolded protein response activation by deubiquitinating DNAJA1 after subarachnoid hemorrhage

Background: Mitochondrial dysfunction plays a critical role in early brain injury (EBI) following Subarachnoid Hemorrhage (SAH) and represents a promising therapeutic target.The mitochondrial unfolded protein response (UPR^mt) maintains mitochondrial homeostasis and enables neurons to cope with oxidative stress. In this study, we explored UPR^mt activation mediated by OTU-deubiquitinating enzyme 1 (YOD1)/DnaJ homolog subfamily A member 1 (DNAJA1) and its role in SAH.

Methods: We isolated UPR^mt positive (UPR^mt+) and UPR^mt negative (UPR^mt-) primary neurons by flow cytometry and validated their differential tolerance to oxidative stress following SAH. We then explored the underlying causes of differential levels of UPR^mt activation. By combining molecular docking, co-immunoprecipitation, and protein stability assays, we established that YOD1 regulates the deubiquitination of DNAJA1. In addition, we assessed the neuroprotective role of YOD1 after SAH in vivo and in vitro models.

Results: UPR^{mt +} neurons exhibited reduced oxyhemoglobin (OxyHb)-induced Apoptosis and mitochondrial damage compared with UPR^mt- neurons. DNAJA1 was upregulated and binding to HSP70 led to a strong activation of UPR^mt. DNAJA1 stability was regulated by the ubiquitin-proteasome system, and YOD1 stabilized DNAJA1 via deubiquitination. Neuron-specific YOD1 overexpression preserved mitochondrial function, reduced neuronal Apoptosis in vitro and in vivo, and improved neurological outcomes in SAH.

Conclusion: YOD1 stabilizes DNAJA1 through deubiquitination, promoting UPR^mt activation to mitigate mitochondrial dysfunction and neuronal death during EBI following SAH.