Genes that make teeth grow in a row

Ever wonder why sharks get several rows of teeth and people only get one? Some geneticists did, and their discovery could spur work to help adults one day grow new teeth when their own wear out.
A single gene appears to be in charge, preventing additional tooth formation in species destined for a limited set. Scientists at University of Rocheste bred mice that lacked that gene and the rodents developed extra teeth next to their first molars.

Also intriguing is the fact that all the mice born without this gene, called Osr2, had cleft palates severe enough to kill. So better understanding of this gene might play a role in efforts to prevent that birth defect.
Teeth may not be visible until long after birth, but they start to form early in embryo development. Teeth ultimately erupt from a thickened band of tissue along the jaw line called the dental lamina, a band that forms in a top layer of the gum called the epithelium. Scientists have long thought the signals for tooth formation must lie in that tissue layer as well. But the Rochester team found that all the action takes place instead in a deeper cell layer called the mesenchyme.

Dr. Rulang Jiang, a geneticist at Rochester’s Center for Oral Biology showed that the Osr2 gene is like a control switch, it turns on and off the downstream actions of other genes and proteins. In that mesenchymal tissue, the Osr2 gene works in concert with two other genes to make sure budding teeth form in the right spot. Knocking that molecular pathway out of whack causes either missing or extra teeth to result, Jiang showed in a series of mouse experiments.
Time alone will tell us what lies in the future but we sure can hope for a day when becoming edentulous is no longer a concern.