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Summary: The gene TP53 is a tumour suppressor, that is activated when cell suffer DNA damage. The encoded protein either repairs or kills the cells, thereby pr
by folli 9y ago
Summary:
The gene TP53 is a tumour suppressor, that is activated when cell suffer DNA damage. The encoded protein either repairs or kills the cells, thereby preventing the cell to become cancerous.
Humans and most other mammals have only one copy of this gene, while Elephants (which are known for their very low cancer rates) have twenty copies of this gene.
Compared to other mammals, compromised Elephant cells are killed at a much higher rate, instead of being repaired.
However, this is most likely not the only factor at play.
- agumonkey 9y agoCould you make a curated list of the other factors ?
- petard 9y agoCurious what the downsides / trade-off is to having twenty copies of this gene.
- test1235 9y ago20 copies seems ridiculously redundant evolutionarily speaking. There must be other uses for this gene that having any fewer would mean a lower survival rate. I wonder if this means resistance against mutation and lower rates of adaptability to environment?
- castratikron 9y agoHumans only have one in their genome. You get one from each of your parents. So everyone has two copies of p53. You can afford to lose exactly one of those copies, but once you lose the second...
- folli 9y agoWell, if you count this way then elephants have 40 copies. While talking about number of genes in mammals diploidy is usually implicitly assumed.
- Aardwolf 9y agoHow does this tumor suppressor know what is a good cell and what is a bad cell? is there a simple heuristic to decide that?
- folli 9y agoTP53 is activated by phosphorylation (i.e. the addition of a phosphoryl group to the enzyme). The enzymes which phosphorylate TP53 in turn respond to several types of stresses (e.g oxidation, membrane damage, heat) and a cascade of checkpoints that respond to different kinds of DNA damages. Furthermore, there's an additional protein (HDM2) that binds to TP53 in healthy cells and deactivates TP53.
- folli 9y agoCheck out the "Regulation" paragraph in wiki: https://en.wikipedia.org/wiki/TP53#Regulation https://en.wikipedia.org/wiki/TP53#Regulation But in short, no, there's not a simple heuristic. As most often the case in the cell, it's a finely tuned balance of several pathways, which tips in one direction or the other depending on the environment and all the other pathways in the cell.