Enzyme Responsible for Bone Deterioration in Rheumatoid Arthritis

A new study has determined an enzyme that could be responsible for bone deterioration in rheumatoid arthritis. The enzyme, Smad Ubiquitin Regulatory Factor 1 (Smurf1), was found to be in charge of two main proteins that drive bone-building and therefore could cause bone loss.

Rheumatoid arthritis affects around 1.3 million Americans. It is an autoimmune disease that causes inflammation, swelling, pain and deformity of joints. In later stages it can also cause bone loss due to enzymes digesting bone and cartilage. This often causes more pain and loss of movement. Rheumatoid arthritis is a chronic, systemic disease, which means it does not go away and can affect other parts of the body. The exact cause of rheumatoid arthritis is unknown.

The study, which was published in an August issue of The Journal of Biological Chemistry, was held by researchers at the University of Rochester Medical Center with the goal of helping to create drugs to the reverse the process of thinning bones related to rheumatoid arthritis. They were already aware that an overproduction of the immune system chemical called TNF alpha (tumor necrosis factor alpha) decreases osteoblasts, which are bone-building cells. While fully aware that this happens and causes bone thinning, scientists have been unaware of how or why the osteoblasts were decreased by the TNF alpha chemical.

For the experiment they used mice and found that TNF alpha has an effect on osteoblasts through the Smurf1 enzyme. They also found that the Smurf1 enzyme turns off two bone building proteins and solved the mystery of why TNF alpha affects the osteoblasts in the way that it does.

Because of the study, it is now known that Smurf1 signals the proteins and causes the damage that happens during overproduction of TNF alpha. This new information will enable scientists to begin working on creating drugs that can shut down Smurf1 and stop bone thinning.

The study also found that mice with less Smurf1 had thicker bones. This poses the question to whether shutting down Smurf1 would also help with different forms of osteoporosis. There is much more work to be done and more research to be performed, but this new information is certainly exciting the medical world.


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