Researchers have uncovered a biochemical pathway involving tumour suppressor proteins that changes the expression of genes in neural stem cells as the cells age. This casts the ebbing regenerative capacity of ageing tissues as a trade-off that keeps cancer at bay.
Sean Morrison at the University of Michigan in Ann Arbor and his colleagues worked out that the decrease in Hmga2, a regulator of gene expression, that occurs as neural stem cells age allows levels of the tumour suppressors p16Ink4a and p19Arf to increase. This leads to lower self-renewal rates. The researchers counted the number of neural cells per section of intestine (pictured) as one measure of self-renewal.
Hmga2 promotes cell renewal in young mice by maintaining low tumour suppressor levels. In old mice, however, avoiding cancer takes precedence over keeping neural matter youthful.
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Molecular biology: Stemming senescence. Nature 455, 1152 (2008). https://doi.org/10.1038/4551152c
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DOI: https://doi.org/10.1038/4551152c
