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Molzahn, Cristen

University of British Columbia

Aging and protein aggregation diseases are inextricably linked. During aging, cellular protein quality control declines which results in diminished protein homeostasis (proteostasis). In model organisms, such as C. elegans, proteostatic decline with age has been linked to the onset of aggregation of proteins in wild-type animals. However, this correlation has not been extensively characterized in aging mammals. To investigate the potentially aggregated portion of the proteome, detergent-insoluble fractionation was used to isolate proteins that become insoluble with age in mouse brain tissue. Quantitative mass spectrometry was used to identify 171 proteins enriched in the detergent-insoluble fraction of older mice. This data was then compared with published datasets using detergent-insoluble fractionation with mouse brain tissue derived from various ages and disease models. Comparison of protein features across the datasets revealed that features associated with proteins found in the pellet fraction differ depending on the ages of the mice. In general, insoluble proteins from young mice were more likely to be RNA-binding, more disordered and more likely to be found in membraneless organelles. These traits become less prominent with age within the combined dataset, as proteins with more structure enter the pellet fraction. These findings suggested that there are likely alterations in the folding of the highly structured proteins that are affected by aging that cause them to become insoluble. Replication of these experiments in the cortex and hippocampus yielded detergent-insoluble proteins with similar features. In addition, consistent enrichment of subunits of the extracellular C1q complex was also observed in both brain regions along with an increase in immunoglobulin signal indicating that increased inflammation may contribute to the insolubility of certain proteins. To further investigate possible structural changes in the soluble portion of the proteome, limited proteolysis was used. These altered proteins tend to have more charged residues and annotated phosphorylation sites and are enriched for synaptic proteins. The complementary approaches employed in this study revealed minute alterations of the proteome that may help to better explain the slow decay of proteostasis observed upon aging.

Text

2023-12-14

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/86949

Biochemistry and Molecular Biology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/