Ancient Dental Gene Set Governs Development and Continuous Regeneration of Teeth in Sharks; Knowledge May Inform Efforts to Address Tooth Loss in Humans

A new insight into how sharks regenerate their teeth, which may pave the way for the development of therapies to help humans with tooth loss, has been discovered by scientists at the University of Sheffield (UK). The study has identified a network of genes that enables sharks to develop and regenerate their teeth throughout their lifetime. The genes also allow sharks to replace rows of their teeth using a conveyer-belt-like system. Scientists have known for some time that certain fish, such as sharks and rays, develop rows of highly specialized teeth with the capacity for lifelong regeneration. However, the genetic mechanisms which enable this to happen were poorly understood. Now, a research team, led by Dr. Gareth Fraser from the University of Sheffield's Department of Animal and Plant Sciences, has identified how a special set of epithelial cells form in the shark. These cells, called the dental lamina, are responsible for the lifelong continuation of tooth development and regeneration in sharks. Humans also possess this set of cells, which facilitate the production of replacement teeth, but only two sets are formed, baby and adult teeth, before this set of specialized cells is lost. The Sheffield-led team show that these tooth-making genes found in sharks are conserved through 450 million years of evolution, and probably made the first vertebrate teeth. These “tooth” genes, therefore, make all vertebrate teeth from those in sharks to those in mammals, but in mammals like humans, the tooth regeneration ability that utilizes these genes has been highly reduced over time. Sheffield’s Dr. Fraser said: "We know that sharks are fearsome predators and one of the main reasons they are so successful at hunting prey is because of their rows of backward pointing, razor-sharp teeth that regenerate rapidly throughout their lifetime, and so are replaced before decay.”
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