Skeletal muscle aging drives sex- and compartment-specific protein insolubility that is modifiable by proteostasis-directed treatments

Aging in skeletal muscle increases aggresome- and amyloid-positive aggregates while leaving bulk insoluble protein unchanged, and these insolubility shifts are sex- and compartment-specific.

• Why it matters: Proteostatic decline is linked to aggregation, but how protein insolubility changes across muscle compartments during aging—and whether it can be modified—was unclear.
• What they did: Using light/electron microscopy, quantitative proteomics, and stable-isotope labeling, the study measured age-associated protein insolubility and tested responses to exercise and rapamycin.
• The result: Exercise and rapamycin partially reversed age-linked changes in protein abundance and soluble–insoluble partitioning without increasing protein synthesis, suggesting proteostatic maintenance may be a key target.

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