The UF research was sparked by studies of gene activity in the limb buds of mice by William J. Scott, D.V.M., Ph.D., a professor of pediatrics at the University of Cincinnati. Scott used a microarray experiment to examine gene expression levels in the ectoderm of mice limb buds, finding activity that could not be possible without the presence of Sonic hedgehog.

UF researchers were able to advance this investigation from cell studies to developing mice embryos by knocking out gene expression in a small region of the ectodermal layer. It allowed them to observe early limb development in the absence of Sonic hedgehog signaling.

"The view had been if you reduce signaling, if anything you would get fewer fingers," said Scott, who did not participate in the UF research. "We now know we can't disregard Sonic hedgehog signaling in the ectoderm. It still has its predominant effect in the tissue where it is made, but it does something more than we thought it did previously. When we try to understand problems that arise with limb growth in humans, we will be able to examine those possibilities."

Harfe said the next phase of the work will be to observe what happens when Sonic hedgehog signaling is disrupted through larger segments of the ectodermal layer. Ultimately, researchers hope the work will lead to quality of life improvements for people.

"We would like to repair limb defects in humans and enhance regeneration of limbs, helping people who might cut off fingers in an accident, for example," Harfe said.

Source: University of Florida