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Researchers have discovered a gene that plays a significant role in the effects of aging. Disabling this gene doubled the lifespan of roundworms. The discovery may offer new insights into human aging.
Aging
Yes, it’s about roundworms. Yet, I find myself more excited about this topic than my other options to write about today. A new study that (again) demonstrates how strength training is beneficial for the elderly, for example [1]. Even if they only do it once a week. We’ve described such studies often enough.
This research on roundworms and similar studies on the influence of genes, however, could prove to be of much greater significance for humans. The ‘elderly’ from the not chosen topic might in the future, thanks to discoveries like those with the roundworms, not be called elderly at all.
It’s often thought that we age due to a slow accumulation of unrepaired damage at the cellular level in our bodies. Aging would result from a trade-off of energy allocation between the ability to grow, reproduce, and survive. But now we know that disabling certain genes in adults can extend lifespan without compromising the ability to reproduce.
Dr Alexei Maklakov of the University of East Anglia.
Genes and Lifespan
Maklakov and colleagues from Uppsala University tested a new theory in their research. According to this theory, there are genes programmed to help us grow and reproduce in our youth. However, if their function remains active in later life, this could cause problems. If this theory is correct, then disabling the expression of these genes in adults would slow down aging.
In their study, the researchers examined a gene called DAF-2 [2]. This gene has previously been linked to aging in roundworms. They found that lowering the expression of this gene extended the lifespan of the worms. This had no negative effect on the worms’ ability to reproduce. In fact, their offspring turned out to be fitter.
DAF-2 is the insulin receptor gene that plays a key role in the action of IGF-1 (insulin-like growth factor). If you’re already lost by this sentence, don’t worry: I’ll explain it as simply as possible.
Growth or Life?
IGF-1 can be seen as an example where the balance between growth and survival tips towards growth. IGF-1 is involved in the growth of various organs and tissues, including muscles. Some bodybuilders and athletes have already used IGF-1 as a doping agent for more muscle mass by using growth hormone that increases the production of IGF-1.
However, increased activity of IGF-1 has also been associated with a shorter lifespan in many different animal species and humans [3,4].
As expected, we found that the worms lived more than twice as long when IGF-1 activity was reduced. Remarkably, we also found that their offspring were fitter and produced more offspring themselves. We kill two birds with one stone. We improve the health and lifespan of the parents and the health of their offspring. This challenges the idea that aging is a trade-off between energy allocation for reproduction and survival.
The researchers’ findings indicate that suboptimal expression of certain genes as adults is at the root of aging. Their results essentially show that natural selection optimizes this gene expression in our younger years but is not strong enough to do so later in life.
Naturally, I wonder what lowering the activity of IGF-1 meant for the gains of the roundworms.
References
- Johanna K. Ihalainen, Alistair Inglis, Tuomas Mäkinen, Robert U. Newton, Heikki Kainulainen, Heikki Kyröläinen, Simon Walker. Strength Training Improves Metabolic Health Markers in Older Individual Regardless of Training Frequency. Frontiers in Physiology, 2019; 10
- https://www.frontiersin.org/articles/10.3389/fphys.2019.00032/full
- Martin I. Lind, Sanjana Ravindran, Zuzana Sekajova, Hanne Carlsson, Andrea Hinas, Alexei A. Maklakov. Experimentally reduced insulin/IGF-1 signaling in adulthood extends lifespan of parents and improves Darwinian fitness of their offspring. Evolution Letters, 2019;
- https://onlinelibrary.wiley.com/doi/full/10.1002/evl3.108
- Junnila RK, List EO, Berryman DE, Murrey JW, Kopchick JJ. The GH/IGF-1 axis in ageing and longevity. Nat Rev Endocrinol. 2013;9(6):366-376.
- Milman, S. , Atzmon, G. , Huffman, D. M., Wan, J. , Crandall, J. P., Cohen, P. and Barzilai, N. (2014), Low insulin‐like growth factor‐1 level predicts survival in humans with exceptional longevity. Aging Cell, 13: 769-771.
- https://onlinelibrary.wiley.com/doi/full/10.1111/acel.12213
