Research at the U-M School of Dentistry may offer some new insights into explaining how mechanical forces stimulate bone formation.
In a paper published in the February 26th issue of The Journal of Cell Biology, Dr. Renny Franceschi and his team reported that the mechanical forces are transmitted to the bone-forming cells, or osteoblasts, by cell surface receptors (integrins) that directly link osteoblasts to the surrounding bone cellular matrix.
In studies with transgenic mice, Franceschi's group showed that integrins stimulate bone formation by activating the extracellular signal regulated mitogen-activated protein kinase pathway (ERK/MAPK pathway) leading to the expression of bone-forming genes. They also showed that the ERK/MAPK functions by specifically phosphorylating a nuclear transcription factor, Runx2.
"Bone is known to be highly responsive to mechanical forces. In fact, weight-bearing exercise is one of the most dramatic ways to stimulate bone formation," Franceschi said. "But our research is the first demonstration that this pathway can stimulate bone formation in animals."
Franceschi said the work also suggests that pharmacological manipulation of the ERK/MAPK pathway in bone may be a way of stimulating bone formation to treat osteoporosis and periodontal disease.
Others participating in the study were Dr. Chunxi Ge, the lead author and research fellow in the School's Department of Periodontics and Oral Medicine, and Drs. Guozhi Xiao, assistant research scientist in POM, and Di Jiang, student research assistant.