In the Dec. 21, 2006 online edition of the scientific journal Development, UW researchers report on laboratory evidence that suggests that Wnt/Beta signaling also promotes the regeneration of tail fins in zebrafish. Another, distinct signaling pathway activated by a different kind of Wnt protein called Wnt5b, turns down the genes that are turned on by Wnt/Beta-catenin, impairs cell proliferation, and inhibits fin regeneration. Fish that have a mutant Wnt5b protein regenerate missing tails very quickly. Too much of another related protein, Wnt8, also increases cell proliferation in the regenerating fin.
"We can actually increase the rate of regeneration by turning on these genes," Moon said.
The researchers also noted, "We show that Wnt/Beta-catenin signaling is activated in the regenerating zebrafish tail and is required for the formation and subsequent proliferation of the progenitor cells of the blastema." A blastema is a little nub of cells that directs regeneration, much like the conductor of an orchestra. By directing cell communication, these few cells grow into an organ or body part, in this case, a tail fin.
"It is most likely the inability of humans to form a blastema in the first place that renders us unable to re-grow arms and legs," said Cristi Stoick-Cooper, a graduate student in the multidisciplinary Neurobiology and Behavior program at the UW, who, with Gilbert Weidinger, now of the Technical University of Dresden (TUD), Germany, was first co-author of the study. The research was done in Moon's lab.
"Our study is the first to identify a gene (Wnt5b) that inhibits regeneration," said Weidinger,
Source:University of Washington