Selective Lysosome Membrane Turnover Is Induced by Nutrient Starvation

Area of Science:

• Cell Biology
• Autophagy Research
• Lysosome Biology

Background:

• Lysosome function is critical for cellular homeostasis.
• Mechanisms maintaining lysosome health, particularly quality control, are not fully understood.
• Lysosome turnover and degradation pathways require further characterization.

Purpose of the Study:

• To develop a method for measuring lysosome turnover.
• To identify novel mechanisms of lysosome membrane degradation.
• To investigate the role of LC3 lipidation in lysosome quality control.

Main Methods:

• Development of a novel assay to quantify lysosome turnover.
• Induction of cellular stress (glucose starvation, osmotic stress) to study lysosome response.
• Genetic manipulation (ATG5 knockout) to assess the role of LC3 lipidation machinery.
• Microscopic analysis to observe intraluminal vesicle formation and microautophagy.

Main Results:

• A selective lysosome membrane degradation mechanism was identified, involving LC3 lipidation and microautophagy.
• This mechanism is activated by metabolic or osmotic stress.
• Cells lacking ATG5 exhibited impaired lysosome size and degradative capacity regulation under stress.
• LC3 lipidation was shown to induce intraluminal vesicle formation within lysosomes.

Conclusions:

• A novel stress-induced pathway for lysosome membrane turnover has been uncovered.
• LC3 lipidation plays a key role in this selective degradation process via microautophagy.
• This mechanism contributes to the regulation of lysosome size and activity during cellular stress.