Disrupted synaptic vacuolar H⁺-ATPase renders synaptic vulnerability to Alzheimer’s disease

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Abstract

Defective synaptic transmission is a prominent pathology that underlies cognitive deficits in Alzheimer’s disease (AD), highlighting the need to elucidate molecular mechanisms of synaptic failure. Vacuolar H+-ATPase (V-ATPase), a proton-pumping enzyme, is essential for synaptic vesicle acidification and neurotransmitter loading. However, whether SV-associated V-ATPase is vulnerable to AD remains unclear. Here, using SV-rich fractions from postmortem brain tissues, we identified SV-associated V-ATPase deficits, including decreased enzymatic activity, impaired complex assembly, and altered expression of its key subunits in AD. SV-associated V-ATPase dysfunction was further associated with pathological and clinical characteristics of AD. Genetic downregulation of the V-ATPase V1D subunit, a component reduced in AD brains, disrupted V-ATPase proton transport and impaired SV acidification. Further experiments using 5×FAD mice, which exhibited AD-like SV-associated V-ATPase deficits, demonstrated the deleterious impact of V-ATPase dysfunction on SV acidification and synaptic transmission including presynaptic neurotransmitter release. In addition, ex vivo studies identified amyloid β–induced oxidative stress as a driver of V1D loss and V-ATPase disassembly, linking AD pathology to SV-associated V-ATPase dysfunction. These findings indicate that SV-associated V-ATPase dysfunction contributes to synaptic failure and cognitive deficits in AD. Therapeutic avenues to mitigate V-ATPase dysfunction have the potential to attenuate synaptic failure for the management of AD.

Authors

Yanting Chen, Khloud Ashraf Farouk Emam, Shuwen Yue, Jing Tian, Tienju Wang, Albert Park, Shalini Mishra, Gagan Deep, Zi-Jun Wang, Heng Du, Lan Guo