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I may be misremembering, but I think senescence is often induced as a response to damage -- a protective measure, since damaged cells are liable to become cance
by cperciva 10y ago
I may be misremembering, but I think senescence is often induced as a response to damage -- a protective measure, since damaged cells are liable to become cancerous if allowed to continue to divide.
As for why the cells become senescent rather than merely dying -- well, even senescent cells retain some function. If damaged cells died rather than becoming senescent, it would presumably result in more deaths in situations where a large number of cells are damaged.
It may be that a drug which kills senescent cells results in a decrease in chronic disability but an increase in deaths... an interesting trade-off!
- Danihan 10y agoWell, all cells convert oxygen and sugar into energy, including old cells and cancer cells. Like you said, cellular senescence is a trade-off -- the body doesn't want these damaged cells to keep dividing per se, yet they are still useful for continuing to covert sugar and oxygen into energy to use as needed. We do have a mechanism for getting rid of damaged cells in general: autophagy. However, autophagy seems to be mostly triggered when there is an energy deficit, for instance during fasting or during intense exercise. This is probably why fasting and exercise are proven over and over to be beneficial to health, they essentially trigger a "cleaning cycle" of cellular autophagy within the body. I'm not sure autophagy typically includes senescent cells, my understanding is that it's primarily targeted towards cells that have damaged mitochondria.
- cperciva 10y agoEven if autophagy eats cells randomly, it will reduce the proportion of senescent cells, since the removed cells will eventually be replaced by newly divided (and non-senescent) cells.