According to popular science media “telomere-shortening after cell-division” is one of the many reasons for ageing. Is this true? Is it possible to fix this shortening? If yes, how will it affect ageing? And finally, how likely is it that we could witness a cure for ageing (or even reverse it) through genetic engineering within our lifetime?
Telomere shortening can cause aging, in some ways. Telomeres shorten with every division, and when they get too short, a cell either senesces or apoptoses. However, certain cells are always dividing, like stem cells, and we can’t run out of those. In cells like those, an enzyme called telomerase is active. Telomerase adds the telomere sequence, TTAGGG, onto the ends of telomeres. Some people have mutations in telomerase-encoding genes that result in loss of function. These people have very short telomeres, and they can develop conditions such as bone marrow failure, pulmonary fibrosis, liver disease, and early greying. Mind you, this is a small percent of the population. So you might think, well what if we just upregulate telomerase in everyone so our telomeres are long? Unfortunately, this wouldn’t be good either. More and more research is coming out saying that particularly long telomeres predispose to certain cancers, like melanoma and leukemia. The idea is that cells that acquire a mutation and become cancerous wouldn’t die out because the cell doesn’t get the signal from short telomeres to apoptose or senesce. There’s a lot more going on here, and we certainly don’t know everything.