A molecular circuit breaker has been identified by biologists at Duke University Medical Center that directs the mechanism by which the zebrafish regrows its missing fins.
The researchers say that the zebrafish exploits microRNAs — small pieces of ribonucleic acid (RNA) that can potentially control the activity of dozens of different genes — to control the regeneration of is organs and tissues.
They say that one or more microRNAs appear to be important to keep the regeneration process on hold until the fish needs new tissue. When the fish gets injured, it damps down levels of these microRNAs to aid regrowth of its organ, they add.
According to the researchers, the ability of the zebrafish to replace its amputated fins is particularly sensitive to levels of a particular microRNA called miR-133.
Telling about their observations during the study, the researchers said that fin regeneration slowed when the concentration of miR-133 was increased, whereas it sped up when its levels were dropped.
Experts believe that understanding how zebrafish repair themselves may pave the way for new therapies to cure human conditions caused by damaged tissue like heart failure, diabetes and spinal cord injuries.
"They probably need to have mechanisms to reduce the potential for unwelcome growth. The implication is that in order to make human tissue regenerate more effectively, we might want to look at some of these microRNAs as potential targets," said Dr. Kenneth Poss, assistant professor of Cell Biology and one of the senior authors of the study.
In the study report, published in the journal Genes & Development, the researchers expressed their belief that mammals might have the same tissue regeneration capability as zebrafish, salamanders and newts, but it was locked away somewhere in their genome and silenced in the course of evolution.
"The key is finding a way to turn on this regenerative ability in humans," Dr. Poss said.
"Our work shows microRNAs appear to have an important role in regenerating complex tissues. Further studies could help us discover potential ways to stimulate this ability in mammals," Dr. Poss said.