: the biological process that involves the enzymatic breakdown of a cell's cytoplasm or cytoplasmic components (such as damaged or unneeded organelles or proteins) within the lysosomes of the same cell
Most of the time, cells sweep away this debris. They even recycle it for fuel. Through the process of autophagy, or "self-eating," cells create specialized membranes that engulf junk in the cytoplasm and carry it to a region of the cell called the lysosome, where the waste is broken down and burned for energy. Gretchen Reynolds
Certain environmental cues (such as starvation, high temperature, low oxygen, hormonal stimulation) or intracellular stress (damaged organelles, accumulation of mutant proteins, microbial invasion) activate signalling pathways that increase autophagy. Beth Levine
… proliferating [cancer] cells maintain a nutrient supply by hijacking a natural cell-housekeeping process called autophagy, in which cells chop up and dispose of damaged or obsolete cell components such as proteins. Nathan Seppa

Examples of autophagy in a Sentence

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The researchers also showed that disrupting F-acting in aged brains restored brain autophagy to levels seen in youth and reversed certain cellular markers of brain aging. New Atlas, 2 Nov. 2024 The researchers found that preventing F-actin accumulation, caused more autophagy in the brains of aged fruit flies. New Atlas, 2 Nov. 2024

Word History

Etymology

borrowed from French autophagie, from auto- auto- + -phagie -phagy

Note: As a term in cell biology introduced by the Belgian immunologist Jules Bordet (1870-1961) in "La bactériophagie ou l'autolyse microbienne transmissible," Volume jubilaire publié à l'occasion du centenaire de la Société royale des sciences médicales et naturelles de Bruxelles (Brussels, 1922), p. 363.

First Known Use

1924, in the meaning defined above

Time Traveler
The first known use of autophagy was in 1924

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Cite this Entry

“Autophagy.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/autophagy. Accessed 13 Mar. 2025.

Medical Definition

autophagy

noun
plural autophagies
: digestion of cellular constituents by enzymes of the same cell
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