Dietary self-selection can compensate an age-related decrease of rat liver 20 S proteasome activity observed with...

Area of Science:

• Aging research
• Molecular biology
• Nutritional science

Background:

• Aging is associated with decreased proteasome activity and increased accumulation of damaged proteins.
• Dietary protein intake naturally decreases in aged rats.
• Proteasome dysfunction contributes to age-related cellular damage.

Purpose of the Study:

• To investigate if self-selected protein intake in aged rats can prevent age-related declines in proteasome activity.
• To assess the impact of dietary self-selection on proteasome function and oxidized protein degradation in aging rats.

Main Methods:

• Comparison of proteasome activity and oxidized protein degradation in mature (18-month-old) and aged (33-month-old) rats.
• Analysis of rats fed a standard diet versus rats allowed to self-select their diet.
• Measurement of four peptidase activities and degradation of oxidized glutamine synthetase.
• Proteasome subunit analysis using two-dimensional gel electrophoresis.

Main Results:

• Self-selecting aged rats restored peptidylglutamyl-peptide hydrolase activity to levels seen in mature rats.
• Degradation of oxidized glutamine synthetase was partially restored in self-selecting aged rats.
• Proteasomes from self-selecting aged rats showed increased trypsin-like and chymotrypsin-like activities compared to aged rats on a standard diet.
• Aged rats on a standard diet exhibited increased protein spots in proteasome subunits, indicating accumulation of damaged proteins.

Conclusions:

• Dietary self-selection in aged rats can partially restore proteasome function and reduce the accumulation of oxidatively damaged proteins.
• These findings suggest that modulating protein intake through self-selection may be a viable strategy to mitigate age-related proteasome decline.
• Proteasome-mediated proteolysis plays a crucial role in preventing the buildup of damaged proteins during aging.