Autophagy
Autophagy is the body’s natural process of breaking down and recycling damaged or worn-out parts of cells. The word comes from Greek and means “self-eating.” This process helps cells remove unnecessary or defective components and reuse their building blocks to create new, healthy cell parts.
Autophagy acts as a cellular housekeeping system. As cells age, damaged proteins, worn-out organelles, and other waste products accumulate. By removing this cellular debris, autophagy helps maintain healthy cell function and prevents the build-up of harmful materials that could interfere with normal biological processes.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10509423/
The process becomes more active when cells experience stress, such as a shortage of nutrients or oxygen. During autophagy, damaged cell components are enclosed within structures called autophagosomes, which then fuse with lysosomes. The lysosomes break down the contents into smaller molecules that the cell can reuse for energy and repair.
Research suggests that autophagy may be stimulated by fasting, calorie restriction, regular exercise, and, in some cases, ketogenic diets. However, most evidence regarding fasting-induced autophagy comes from animal studies. Scientists have not yet determined exactly how long humans need to fast to significantly increase autophagy, and responses may vary between individuals and different tissues.
Autophagy molecular machinery. The process of autophagy consists of several consequent molecular and subcellular morphological changes. In the early steps, the activation of autophagy upstream molecules leads to phagophore formation and expansion. These units sequester the damaged organelles, aggregated proteins, etc. By the activation of several Atgs, phagophores mature into autophagosomes followed by fusion with lysosomes and the formation of autophagolysosomes. Inside the autophagolysosomes, enzymatic digestion is orchestrated via varied hydrolases, leading to massive enzymatic digestion. The digested cargo is recycled into the cytosol or protrudes out of the host cells. Atg, autophagy-related protein; mTOR, mammalian target of rapamycin. {see the pic. below}
Autophagy plays an important role in maintaining overall health. It helps remove damaged cell components, supports the immune system by helping eliminate certain bacteria and viruses, and contributes to normal cell survival during periods of stress. Because autophagy naturally declines with age, reduced cellular recycling may contribute to age-related changes and disease.
Accumulated evidence suggests that intermittent fasting or calorie restriction can lead to the induction of adaptive autophagy and increase longevity of eukaryotic cells. However, prolonged calorie restriction with excessive autophagy response is harmful and can stimulate a type II autophagic cell death.
Scientists are actively studying the relationship between autophagy and diseases such as cancer, diabetes, heart disease, Parkinson’s disease, Alzheimer’s disease, liver disease, and kidney disease. In cancer, autophagy appears to have both protective and harmful effects. It may help prevent cancer by removing damaged cellular components, but some established cancers may also use autophagy to survive and continue growing.
NN, DB
