One area Brotto's group focused on was the regulation of calcium metabolism. Calcium is needed both to build strong bones and to make muscles contract. Researchers focused on a muscle specific phosphatase called MIP that decreases naturally as we age that may be involved the regulation of calcium levels in the body. Researchers removed the MIP protein from mice by knocking out the gene that codes for the protein. These mice had muscle weakness and faster aging, as well as reductions in bone densities. The mutant mice also had weakness in smooth muscle function of the contracting arteries and vessels. Interestingly enough, some of these results seemed to be gender specific. The female mice developed osteoporosis, but the males did not. And there was female bias for weakness in heart muscle function that was not seen in the male subjects. This data supports that calcium regulation is different between the two sexes, which may explain why women are more likely to get osteoporosis than men.
A New Approach to Bone Fractures: A Breakdown in Communication Between Muscle and Bone?
For the many diseases that target muscles diet, exercise and hormone therapy are the only treatments. Unfortunately, many patients have health conditions that prevent them from exercising limiting their treatment options. Brotto is hopeful that following the new line of research studying the communication between muscles and bones will identify novel therapies and potentially help millions of people.
When a bone is fractured, it is typically thought to be a defect in the strength of the bone. But the Bone-Muscle team at UMKC hypothesizes that it may be caused from a breakdown in communication between muscles and bones. Muscles put force on bones as they contract, which is known as mechanical loading. Perhaps the muscles put too much force on the bones at the wrong time, which results in a break.
"We would like to discover chemical factors that can bypass the issue of loading and could patch communication on the muscle side or the bone side to make the unity stronger," Brotto said.
Source: Federation of American Societies for Experimental Biology