Getting down to the bone—and the teeth
Most people take for granted that their teeth and bones—throughout their bodies—are strong enough to allow them to chew and walk. For those with a problem in the genes that makes certain extracellular matrix (ECM) proteins, though, that strength is far from a given.
Chunlin Qin, DDS, PhD, professor and Presidential Impact Fellow at the Texas A&M College of Dentistry, studies the roles ECM proteins play in the formation and mineralization of tooth and bone.
Qin worked as a dentist for about 10 years in China and treated many people with problems in the formation of their teeth. When he began his doctoral program, he knew he wanted to study how extracellular matrices work. Since then, his studies have led to a better understanding of how tooth and bone form and the discovery of certain key genes that are required for those structures to form properly.
“I wish to provide clues for the treatment of certain diseases affecting the bone and the tooth,” Qin said, “and discover the mechanism to provide guidance for regeneration of these tissues.”
Qin’s studies have shown that a protein kinase called FAM20C plays critical roles in the formation of all four of the types of mineralized tissues in mammals: bone, enamel, which is the outer layer of tooth crown; dentin, the bulky tissue shaping the contour of a tooth; and cementum, the outer layer of tooth root. The same kinase also affects phosphorus levels throughout the body, which has implications for muscles, fat metabolism and the immune system. In fact, loss of—or mutations in—this gene can cause very severe skeletal and brain developmental problems.
Another ECM molecule called dentin sialophosphoprotein (DSPP) is highly expressed in the dentin and also plays crucial roles in the formation and mineralization of tooth and jaw bone. Its mutations or loss cause a condition called dentinogenesis imperfecta, which affects about one in every 6000 or 8000 people. “Before we design an intervention, though, we need to understand the mechanisms by which teeth and bones are formed,” Qin said.
In healthy people, teeth and bones attract calcium phosphate, which mineralizes them and provides the hardness these structures have. If the encoding genes are lost or mutated, however, patients may have dental disease or bone disease or both.
“I hope my research will provide the underlying science to speed the creation of ways to fix bones and teeth that form improperly,” Qin said. “It’s a major quality of life issue for so many people with these types of genetic diseases, but we’re getting close to understanding what is wrong on the cellular level so that we can help.”