ATAD1 Regulates Neuronal Development and Synapse Formation Through Tuning Mitochondrial Function

Mitochondrial function is essential for synaptic function. ATAD1, an AAA+ protease involved in mitochondrial quality control, governs fission-fusion dynamics within the organelle. However, the distribution and functional role of ATAD1 in neurons remain poorly understood. In this study, we demonstrate that ATAD1 is primarily localized to mitochondria in dendrites and, to a lesser extent, in spines in cultured hippocampal neurons. We found that ATAD1 deficiency disrupts the mitochondrial fission-fusion balance, resulting in mitochondrial fragmentation. This deficiency also impairs dendritic branching, hinders dendritic spine maturation, and reduces glutamatergic synaptic transmission in hippocampal neuron. To further investigate the underlying mechanism, we employed an ATP hydrolysis-deficient mutant of ATAD1 to rescue the neuronal deficits associated with ATAD1 loss. We discovered that the synaptic deficits are independent of the mitochondrial morphology changes but rely on its ATP hydrolysis. Furthermore, we show that ATAD1 loss leads to impaired mitochondrial function, including decreased ATP production, impaired membrane potential, and elevated oxidative stress. In conclusion, our results provide evidence that ATAD1 is crucial for maintaining mitochondrial function and regulating neurodevelopment and synaptic function.