Tiny wonders of the aquarium world, zebrafish can regenerate organs and tissues, including hearts, eye parts and fins. When a fin is lost, the fish regenerates a perfect copy in two weeks by orchestrating the growth of many tissue types, including bone, nerves, blood vessels, connective tissue and skin.
Scientists hope that understanding how zebrafish repair themselves will lead to new treatments for human conditions caused by damaged tissue, such as heart failure, diabetes and spinal cord injuries.
The regeneration regulator is one of a group of recently discovered molecules called microRNAs: small pieces of ribonucleic acid (RNA) that each can potentially control the activity of dozens of different genes. In humans, microRNAs play important roles in cell growth and death, among other functions. There are hundreds of kinds of microRNAs, and scientists are constantly discovering new roles they play.
In zebrafish, one or more microRNAs appear to be important to keep regeneration on hold until the fish needs new tissue, the Duke researchers say. In response to an injury, the fish then damp down levels of these microRNAs to aid regrowth. The team discovered that the ability of zebrafish to replace amputated fins is particularly sensitive to levels of a particular microRNA called miR-133.
The discovery makes sense because any animal that can rapidly grow new tissue needs to keep the system in check, said senior author Kenneth Poss, Ph.D., assistant professor of cell biology. "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."
The results appear in the March 15, 2008 issue of the journal Genes & Development. Postdoctoral scholar Viravuth Yin, Ph.D., a member of Poss' lab, is first author on the study. Funding was provided by the National Institutes of Health, the American Heart Association, the Whitehead Foundation and Pew Charitable Trusts.
Poss and many other cell biologists believe that mammals may have the same tissue regeneration capability as zebrafish, salamanders and newts, but that it is locked away somewhere in our genome, silenced in the course of evolution. "The key is finding a way to turn on this regenerative ability in humans," Poss said.
The Duke researchers began their study by ferreting out any microRNAs present in fins at different stages of regrowth, then measuring whether there was a lot or a little of each molecule.
Dr. Poss' team eventually zeroed in on some of the most important microRNAs for regrowth by studying genetically modified zebrafish. The modification allows a critical signaling pathway to be shut down during regeneration. The pathway sends biochemical cues called growth factors that stimulate cell division and organ growth.
Levels of one microRNA in particular, miR-133, dropped during normal regeneration. But when the scientists blocked the signaling pathway briefly during regeneration, the amount of miR-133 jumped back up to the level found in uninjured fins. Further experiments showed that tweaking the concentration of miR-133 affected fin growth. When levels were raised, fin regrowth slowed; when they were dropped, regeneration sped up.
"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," Poss said.
Debbe Geiger | EurekAlert!
Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover
First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences