Fri. Dec 6th, 2019

Healthy obesity of bears, the superpower that science wants to unravel | Science

There are animals that have super powers. The elephants rarely develop cancer despite having a life expectancy similar to that of humans. A team from the University of Utah identified the cause in 2015. These animals have 38 additional copies of a gene that produces the p53 protein, known for its ability to suppress tumors. In addition, they have a much more efficient mechanism than the human to remove damaged cells from the circulation with the risk of becoming cancerous. Dolphins, meanwhile, have special protection against blood clots, another of the great threats to the health of our species.

Christopher Gregg and Elliot Ferris, from the University of Utah, are two of the researchers who are tracking the genome of several mammalian species in search of the clues of these super powers. On Tuesday they published an article in the magazine Cell reports in which they explore the reasons why animals that hibernate, such as bears, do not develop problems associated with obesity or insulin resistance.

The hiberna gray mouse lemur during the dry season of Madagascar

The hiberna gray mouse lemur during the dry season of Madagascar

His analysis included four species that go into hibernation at some time of the year: the small hedgehog tenrec (Echinops Telfairi), the ground squirrel of thirteen stripes (Ictidomys tridecemlineatus), the gray mouse lemur (Microcebus murinus) and the little brown bat (Myotis lucifugus). These animals, with some variations, spend several months in which their pulsations and breathing drop dramatically – the squirrel lowers its heart rate from 200 beats per minute to about five, and breathing more than a hundred times per minute happens once every five minutes — and those who don't need to feed, urinate or defecate.

To achieve that goal, in the previous months, individuals of these species have to eat to accumulate reserves. Somehow, they become obese and insulin resistant, but in a healthy way. A human with these fluctuations throughout the year would end up suffering from diabetes, hypertension and many other health problems.

The authors of the work compared the genomes of the four species with those of healthy humans and with genes related to the Prader-Willi syndrome, a disease that triggers an insatiable appetite that causes morbid obesity. Thus, they identified regions of the genome of these animals, close to many related to obesity in humans, that would allow them to turn off some elements that control genes related to obesity. In total there are 364 genetic elements related to the regulation of hibernation and obesity.

Researchers are working on epigenomic editing techniques to control obesity

At the moment, this type of extensive genome studies does not have a direct application to our health. Scientists try first to understand how, throughout evolution, common regions of the genome that are now behind obesity or metabolic problems have served different animals to better adapt to their circumstances. In some cases and at different times in animal history, that adaptation meant developing the ability to hibernate for months. For bears, this healthy regulation of obesity allows them to survive during the winter, while lemurs, the only primates that hibernate, that temporary suspension of activity serves them to pass the dry season in Madagascar.

But in addition to obtaining basic information about some biological mechanisms, Gregg and his collaborators already think about how to apply this knowledge. “By understanding the parts of the genome that influence obesity or metabolic syndrome, we can assess a person's risk of developing these diseases throughout their life from their genetic sequence. Thus we could help people adapt their lifestyle to their conditions and in the future also create pharmacological treatments to treat people who have developed obesity, ”says the researcher. "My laboratory is already working with Jason Gertz, from the University of Utah, to develop a technology of epigenetic editing directed using CRISPR with which to control in a personalized way obesity or metabolic activity of patients," he adds.

Meanwhile, Gregg continues to search the ocean for mammalian genetics in search of variants that humans still have and that in some animals have become something like super powers.

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