Macroautophagy

Definition

Macroautophagy is a cellular recycling process in which portions of cytoplasm, damaged organelles, and unwanted proteins are enclosed inside double-membrane structures called autophagosomes and delivered to lysosomes for degradation. It is the form of autophagy most commonly meant when researchers use the word autophagy without qualification. [1] [2] [3]

Why It Matters in Ageing Research

Macroautophagy helps maintain cellular quality control by removing damaged components and supporting metabolic adaptation during stress. With ageing, autophagic activity can become less efficient, which may contribute to loss of proteostasis, mitochondrial dysfunction, inflammation, and reduced tissue resilience. Disabled macroautophagy is recognised as one of the expanded hallmarks of ageing. [4] [5] [6]

Common Confusion

• Macroautophagy is one type of autophagy; other forms include microautophagy and chaperone-mediated autophagy.
• Autophagy is not simply “cellular cleanup”; it also supports nutrient recycling, stress responses, immunity, and development.
• More autophagy is not always better, because autophagy can have context-dependent effects in ageing, cancer, infection, and tissue injury.

Related Reading

• Hallmarks of Ageing
• Autophagy
• Mitophagy
• Proteostasis
• Lysosome
• mTOR

References

1. Mizushima, N., & Komatsu, M. (2011). Autophagy: Renovation of Cells and Tissues. https://doi.org/10.1016/j.cell.2011.10.026
2. Klionsky, D. J., & Emr, S. D. (2000). Autophagy as a Regulated Pathway of Cellular Degradation. https://doi.org/10.1126/science.290.5497.1717
3. Dikic, I., & Elazar, Z. (2018). Mechanism and medical implications of mammalian autophagy. https://doi.org/10.1038/s41580-018-0003-4
4. Lopez-Otin, C., et al. (2013). The Hallmarks of Aging. https://doi.org/10.1016/j.cell.2013.05.039
5. Lopez-Otin, C., et al. (2023). Hallmarks of aging: An expanding universe. https://doi.org/10.1016/j.cell.2022.11.001
6. Rubinsztein, D. C., Marino, G., & Kroemer, G. (2011). Autophagy and Aging. https://doi.org/10.1016/j.cell.2011.07.030