20 March 2008

Organ Regeneration: Disable miR-133 microRNA

Biologists have found a microRNA that regulates fin regeneration in striped Zebrafish. The authors of the discovery Kenneth Poss (Kenneth Poss) and his colleagues from Duke University Medical Center (Duke University) believe that it will help scientists in unlocking the potential of organ regeneration in humans.

Researchers have long come to the conclusion that mammals have the ability to regenerate tissues, including complex organs, is only dormant. This kind of genetic program is just turned off. If you understand how to turn it back on at the level of cells, and then – and whole organs, it will be possible to stimulate, say, the restoration of the heart muscle after an attack, or perhaps even the cultivation of limbs to replace the lost ones.

A lot has been done on the way to this bright future. For example, experimenters have already regenerated the wing of a chicken, learned how to stimulate the self-healing of the heart in rats and discovered unprecedented tissue regeneration in mice.

And it's probably not for nothing that the Pentagon (represented by the DARPA agency) finances work on the study of organ regeneration. However, the transition from experimental animals to humans may take longer than scientists saw at the beginning of the journey. And yet every new knowledge in this area brings the moment when "newt people" will appear.

Or "danio people". This tiny fish can regenerate various organs and tissues, including the heart, eyes and fins. When a fish loses (damages) something from this set, it restores an ideal copy of an organ or its fragment in two weeks, including new bones, nerves, blood vessels, connective tissue and skin.

Biologists have found that microRNAs capable of controlling the work of dozens of genes play an important role in this regeneration. There are hundreds of types of microRNAs, and they affect cell division and death not only in this fish, but also in other animals, and in humans.

Справа – плавник, выросший после повреждения в обычных условиях, слева – у рыбки с нарушенным механизмом отключения синтеза микроРНК miR-133Scientists are constantly discovering new roles of microRNAs in the body. And now, having conducted numerous experiments with striped danio, Poss and his colleagues have determined that the successful regeneration of severed fins is affected by the concentration of miR-133 microRNA in them. In a damaged fin, it drops sharply, which triggers a chain of certain genes, as a result of which a growth factor is produced, and the fin is restored (in the figure on the right).

When the experimenters blocked the genetic pathway calculated by them, the fin grew poorly (in the figure on the left), and the level of miR-133 in it remained the same as in the surviving fin. So this microRNA functioned as a kind of barrier to signal cells to divide. This molecule protected the organ from unnecessary and uncontrolled cell reproduction while everything was in order, and opened the way to regeneration if the organ was damaged.

Poss believes that similar microRNAs and genetic chains that trigger the process of tissue repair can be found in mammals, and hence in humans.

Membrane based on materials ScienceDaily

Portal "Eternal youth" www.vechnayamolodost.ru19.03.2008

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