Gene Network Used to Trace Origins of Early Tooth Development

Darwin had his finches, Morgan had his fruit flies, and scientists today have cichlid fishes to trace the biological origins of jaws and teeth. As reported in the journal PLoS Biology, researchers supported by the National Institute of Dental and Craniofacial Research (NIDCR) report they have deduced a network of dental genes in cichlids that likely was present to build the first tooth some half a billion years ago. The researchers say their finding lays out a core evolutionary list of molecules needed to make a tooth. Todd Streelman, PhD, a scientist at Georgia Institute of Technology in Atlanta and senior author on the study, said the discovery should provide useful information for researchers attempting to coax diseased teeth back to health with biology rather than the traditional hand-held drill.

“To truly understand any part of the body, you must know how it was originally designed,” said Dr. Streelman. “This is especially important when it comes to teeth. The teeth of fishes not only develop distinct sizes and shapes, they are also repaired, shed, and replaced throughout life….But these characteristics, once intertwined, have been decoupled through the ages in higher organisms, and the ability to repair and regrow teeth has been largely lost,” he added. “If we could learn to selectively restore these traits in the dentist’s office, it would mark a major step forward in helping people protect and repair their teeth….this gene network provides a nice evolutionary clue on how best to proceed.” 

In Lake Malawi, one of East Africa’s Great Lakes, scientists can find a great di-versity of dentitions among more than 1,000 cichlid species. Last year, Fraser, et al described a gene network that seemed to control the patterning of tooth size, number, and spacing in Lake Malawi cichlids. “What’s really interesting is this network includes genes that are known to be involved in the patterning of hairs, feathers, and other ectodermally-derived tissues,” said Dr. Fraser. This network is ancient and fundamentally important to creating a dentition, and our work demostrates the power of evolutionary models in biomedical research, added Dr. Streelman. “You don’t need to artificially turn genes on or off under controlled laboratory conditions to see what might happen. The cichlids are nature’s own experiment, and they open up exciting biological opportunities that you just can’t glean as possibilities from traditional model organisms.”