Grant: Project Grant

Poor bone health is a major issue in the aging Canadian population, in which 1 in 3 postmenopausal women and 1 in 6 older men have osteoporosis and half will have a fragility fracture. Hip fracture in people over 65 years of age significantly increases mortality and therefore it is important that we understand the factors that contribute to bone fragility. Lack of exercise, insufficient calcium and vitamin D intake, and loss of estrogen and testosterone with age all negatively impact bone health, but there are also genetic differences that make some people more vulnerable to these skeletal stresses. In our previous studies on bone health we have shown a large variability in expression of two proteins, called G proteins, in human cells. These G proteins are important for cell responses to messages from the hormone and nervous systems.To test the effects of changing G protein levels, we created two mouse types with high levels of each of these proteins in bone cells. Our two mouse lines look normal but both have weaker bone that fractures more easily. In our proposed research we will now test their bones after they eat a diet low in calcium or vitamin D and when we remove their estrogen and testosterone. We will also test if these mice respond differently to exercise and drugs used to increase bone density.Our studies will help us decide if people with high G protein levels are more likely to get osteoporosis or have bone fractures and what we can do to help keep their bones healthy into old age.