FIGURE 1.

Aging disrupts the hippocampal circadian proteome. (A) Experimental design and workflow of the MS-based analysis of proteins extracted from hippocampal tissues of young (9–10 weeks old) and middle-aged (44–52 weeks old) C57BL/6J mice. Samples were collected every 4 h over 2 days, and proteins extracted from tissues of individual mice were digested with trypsin, fractionated, and analyzed by an Orbitrap Elite mass spectrometer. (B) Proteome coverage: Venn diagram displaying the number of proteins quantified in at least two biological replicates per time point in young or middle-aged mice and overlap between ages. (C) Circadian proteins detected in young or middle-aged mice using the Perseus periodicity algorithm (period = 23.6 h; q-value < 0.25). (D) Percent distribution of circadian proteins based on changes in rhythmicity during aging. (E) Heatmaps displaying z-score normalized abundances (log₁₀ LFQ intensities) of circadian proteins detected in young mice and their temporal expression profiles in young mice (left) and middle-aged mice (right). (F) Phase distribution of circadian proteins detected in young mice (green) or middle-aged mice (red). (G) Correlation heatmaps across 48 h in young mice (left) and middle-aged mice (right) for circadian proteins detected in young mice. Pearson correlation coefficients are shown as red (positive) or blue (negative).