Germ cells may regulate aging in vertebrates

A research team at Osaka University has uncovered the mechanism by which females live longer than males. They found that the reproductive cells of both males and females control their lifespan, and that eggs have a molecular mechanism that leads to longer lifespans which is not available to sperm cells.

The research team around Professor Futoshi Ishitani at the Institute for Microbial Diseases, Osaka University used the turquoise killifish in their experiments. Turquoise killifish have a short lifespan of just a few months, with males living shorter than females, and they also undergo a similar aging process to humans. When during embryo development, antisense nucleic acid against the dnd gene was administered to remove the germ cells, the lifespan of males and females was almost the same, with females living even shorter and males living longer than normal, suggesting that germ cells were responsible for the longer lifespan in females.

To identify the molecular mechanism , Professor Ishitani and his team examined the endocrine system of turquoise killifish. They found that females had a decreased level of estrogen, which was accompanied by an increase in lipid synthesis and an increase in blood clotting factors, increasing the risk of cardiovascular disease. They also found that insulin/insulin-like growth factor signaling, which controls body growth, was activated, increasing damage such as oxidative stress. They concluded that in females, eggs may suppress aging by releasing estrogen signals and suppressing insulin/IGF signals. On the other hand, males from which germ cells had been removed showed increased muscle regeneration ability, skin collagen content, and bone mass, all of which normally decrease with age. Gene expression of the Cyp2r1 enzyme, which converts vitamin D into its active form, was increased, and vitamin D signaling was activated in the muscles and skin, suggesting that vitamin D signaling suppressed aging throughout the body.

When vitamin D was administered to normal turquoise killifish, it was found to have an effect of extending the lifespan of both males and females, although there were differences in the effect between the sexes. Vitamin D functioned as an anti-aging hormone. There have been cases in which genetic polymorphisms that may promote vitamin D signaling have been found in long-lived humans, so it is expected that vitamin D may also contribute to human longevity. However, administering excessive amounts to turquoise killifish does not enhance the effect, and it is known that excessive intake in humans and mice can cause health problems, so it is necessary to consider the appropriate amount.

Germ cells may regulate aging in vertebrates
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