Abstract Biological variables can directly impact disease vulnerability and clinical presentation. For example, age remains the greatest risk factor for developing most neurodegenerative diseases, and while sex differences have historically been understudied, there is increasing evidence that sex can also impact disease outcomes. Alpha synuclein (αSyn) has long been implicated in the development of a multitude of neurodegenerative diseases, however, some of its normal functions remain elusive. αSyn is part of the synuclein family of proteins, a highly evolutionarily conserved group which includes beta (βSyn) and gamma synuclein. αSyn and βSyn are increasingly being studied as potential biomarkers for disease development and progression. βSyn has also been shown to be an endogenous inhibitor of αSyn aggregation, and can be upregulated in response to the removal of αSyn. Recent studies indicate that synuclein protein abundance and function could vary with sex and age. However, few studies have rigorously assessed the interaction of these biological variables in normal functioning systems. Without understanding the baseline abundance and function of these proteins, treatments targeting the synuclein family have an increased likelihood of failing in the clinic or of producing negative side effects. Results from our group have shown a sex-specific response to αSyn ablation in mice, such that female animals but not males had impaired spatial learning and memory. The goal of this proposal is to investigate the normal function of αSyn in both sexes at multiple ages. The overall hypothesis is that αSyn is transcriptionally, translationally, or functionally distinct in male and female brains. The interaction of synuclein family proteins with sex and age in different brain regions might underlie previously observed sex- specific responses. I will address the hypothesis by utilizing a conditional knockout mouse model to selectively ablate αSyn from excitatory neurons and test mice of both sexes at different ages. I will study the effects of αSyn ablation on behavior through a learning and memory task, while mass spectrometry will be used assess αSyn post-translational modifications that might impact protein stability and function. Technological advances now allow us to collect transcriptomic and proteomic data from the same animal with high spatial resolution. Therefore, we will also determine the effect of αSyn ablation on the abundance and location of βSyn, which could be upregulated in a compensatory manner. Regional differences in βSyn transcription or translation might contribute to the vulnerability of specific brain regions in the development synucleinopathies. These experiments will provide a deeper molecular and functional understanding of the normal role of αSyn and how it might change with sex and age. Utilization of spatial genomics could provide mechanistic insight into observed sex differences, and reveal new avenues for disease diagnosis and t...