A recent open access paper from a Spanish research group outlines yet another methodology to add to the growing list of ways to increase healthy life span in mice. Progress is signified by diversity these days; there are, I think, more than twenty different demonstrated methods of bringing about meaningful extension of life in mice as of today.
We observed that mice deficient for RasGrf1-/- display an increase in average and most importantly, in maximal lifespan (20% higher than controls). This was not due to the role of Ras in cancer because tumor-free survival was also enhanced in these animals.
Aged RasGrf1-/- displayed better motor coordination than control mice. Protection against oxidative stress was similarly preserved in old RasGrf1-/-. IGF-I levels were lower in RasGrf1-/- than in controls. Furthermore, SIRT1 expression was increased in RasGrf1-/- animals. Consistent with this, the blood metabolomic profiles of RasGrf1-deficient mice resembled those observed in calorie-restricted animals.
Our observations link Ras signaling to lifespan and suggest that RasGrf1 is an evolutionary conserved gene which could be targeted for the development of therapies to delay age-related processes.
The results are similar to those noted for PAPP-A knockout mice - both longer lives and less cancer. At this stage it's anyone's guess as to whether many of these methodologies in fact operate through the same thicket of connections and mechanisms in mammalian biochemistry. Time, and further research, will tell.
RasGrf1 was mentioned here last year in connection with the intriguing bi-maternal mice:
mice artificially produced with two sets of female genomes have an increased average lifespan of 28%. Moreover, these animals exhibit a smaller body size, a trait also observed in several other long-lived mouse models. One hypothesis is that alterations in the expression of paternally methylated imprinted genes are responsible for the life-extension of bi-maternal mice. Considering the similarities in postnatal growth retardation between mice with mutations in the Rasgrf1 imprinted gene and bi-maternal mice, Rasgrf1 is the most likely culprit for the low body weight and extended lifespan of bi-maternal mice.
This latest work adds weight to the supposition quoted above.