Hormone receptors may regulate effect of nutrition on life expectancy not only in roundworms, but perhaps also in humans

Aug. 6, 2013 — A reduced caloric intake increases life expectancy in many species. But how diet prolongs the lives of model organisms such as fruit flies and roundworms has remained a mystery until recently. Scientists at the Max Planck Institute for Biology of Ageing in Cologne discovered that a hormone receptor is one of the links between nutrition and life expectancy in the roundworms.The receptor protein NHR-62 increases the lifespan of the animals by twenty per cent if their calorie intake is reduced. Furthermore, another study showed that the hormone receptor NHR-8 affects development into adulthood as well as the maximum lifespan of the worms. It may be possible that receptors related to these are also responsible for regulating life expectancy in human beings.The roundworm Caenorhabditis elegans lives only about 20 days. This makes it an ideal research subject, as the complete lifecycle of the worm can be studied in a short time. Also, the worm consists of less than a thousand cells, and its genetic make-up has been extensively analysed, and contains many genes similar to humans. The scientists in Adam Antebi’s team at the Max Planck Institute for Biology of Ageing use Caenorhabditis elegans to find out how hormones influence ageing. They are particularly interested in hormone receptors that reside in the cell nucleus, which regulate the activity of metabolic genes.Their results indicate that the receptor NHR-62 must be active for reduced dietary intake to fully prolong the life of worms. …

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Rapamycin: Limited anti-aging effects

July 25, 2013 — The drug rapamycin is known to increase lifespan in mice. Whether rapamycin slows down aging, however, remains unclear. A team of researchers from the German Center for Neurodegenerative Diseases (DZNE) and the Helmholtz Zentrum München has now found that rapamycin extends lifespan — but its impact on aging itself is limited. The life-extending effect seems to be related to rapamycin’s suppression of tumors, which represent the main causes of death in these mouse strains.The findings are reported in the current issue of the Journal of Clinical Investigation.The body’s repair mechanisms begin to fail with increasing age. As a result, signs of wear and tear appear and the risk for many diseases, including Alzheimer’s disease, diabetes, cardiovascular disorders and cancer, increases. “Current efforts to develop therapies against age-related diseases target these disorders one by one,” says Dr. Dan Ehninger, research group leader at the DZNE site in Bonn. “Influencing the aging process itself may be an alternative approach with the potential to yield broadly effective therapeutics against age-related diseases.”In this context, the substance rapamycin is noteworthy. Rapamycin is used in recipients of organ transplants, as it keeps the immune system in check and can consequently prevent rejection of the foreign tissue. In 2009, US scientists discovered another effect: Mice treated with rapamycin lived longer than their untreated counterparts. …

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Chemical that makes naked mole rats cancer-proof discovered

June 19, 2013 — Two researchers at the University of Rochester have discovered the chemical that makes naked mole rats cancer-proof.The findings could eventually lead to new cancer treatments in people, said study authors Andrei Seluanov and Vera Gorbunova. Their research paper will be published this week in the journal Nature.Naked mole rats are small, hairless, subterranean rodents that have never been known to get cancer, despite having a 30-year lifespan. The research group led by Seluanov and Gorbunova discovered that these rodents are protected from cancer because their tissues are very rich with high molecular weight hyaluronan (HMW-HA).The biologists’ focus on HMW-HA began after they noticed that a gooey substance in the naked mole rat culture was clogging the vacuum pumps and tubing. They also observed that, unlike the naked mole rat culture, other media containing cells from humans, mice, and guinea pigs were not viscous.”We needed to understand what the goo was,” said Seluanov.Gorbunova and Seluanov identified the substance as HMW-HA, which caused them to test its possible role in naked mole rat’s cancer resistance.Seluanov and Gorbunova then showed that when HMW-HA was removed, the cells became susceptible to tumors, confirming that the chemical did play a role in making naked mole rats cancer-proof. The Rochester team also identified the gene, named HAS2, responsible for making HMW-HA in the naked mole rat. Surprisingly, the naked mole rat gene was different from HAS2 in all other animals. In addition the naked mole rats were very slow at recycling HMW-HA, which contributed to the accumulation of the chemical in the animals’ tissues.The next step will be to test the effectiveness of HMW-HA in mice. If that test goes well, Seluanov and Gorbunova hope to try the chemical on human cells. “There’s indirect evidence that HMW-HA would work in people,” said Seluanov. “It’s used in anti-wrinkle injections and to relieve pain from arthritis in knee joints, without any adverse effects. …

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