PR003026 (Project)

Description:The synaptic vesicle (SV) cycle is the fastest membrane trafficking and protein sorting process in biology. It enables neuronal communication and cognition, while its disruption contributes to neurodevelopmental disorders and neurodegeneration. How this cycle is maintained throughout the lifespan of a complex organism remains unclear. Here we define the age-stratified SV molecular landscape and identify apolipoprotein E (APOE) as an abundant presynaptic protein that increases in an age- and sex-dependent manner. Using knockout controls, we localize APOE to synapses in cortex and hippocampal subregions using intact tissue and cultured neurons. Super-resolution imaging, cell-type selective expression, and protease protection assays further show that APOE originates from glia and associates with the external surface of SV. Using iGluSnFR and pHluorin optophysiology, we find that APOE modulation reduces glutamate release probability impairing sustained neurotransmission during stimulus trains. These results establish APOE as a cell nonautonomous regulator of the SV cycle. Normal aging male and female cohort: C57BL/6J male and female mice were maintained at The Jackson Laboratory under standard husbandry conditions, including a normal light-dark cycle and standard chow. Animal brains were collected at 3, 6, 12, 18, 24, and 30 months of age for SV-RIP to define age- and sex-dependent changes across the lifespan, with four (n=4) biological replicates per sex at each time-point. This study design enabled direct comparison of male and female aging trajectories under matched conditions over an experimental duration of up to 30 months.