Defining disease mechanisms in mouse models of chondrodysplasia.

Some children are born with severely shortened limbs because their growth plates fail to build bone properly. This fellowship aims to understand exactly why that happens. The researcher has already created mouse models of two human skeletal disorders—PSACH and MED—caused by mutations in the COMP and matrilin-3 genes. In these mice, bone growth stalls because cartilage cells (chondrocytes) stop dividing and die in the wrong places, likely due to cellular stress from the mutant proteins. Now the work will untangle three key questions: whether the unfolded protein response and cell stress drive growth plate failure, whether changes in the cartilage’s structural scaffold contribute, and how much of the damage comes from inside cells versus outside them. This is fundamental science. It will not produce a treatment tomorrow. But by pinpointing the chain of events from a single gene mutation to a misshapen skeleton, the findings could illuminate disease mechanisms not only in PSACH and MED but across a wide range of inherited connective tissue disorders. Understanding how a cell’s stress response derails bone growth may eventually point to molecular targets for therapy—much as basic discoveries about protein folding in yeast opened the door to treatments for cystic fibrosis and Alzheimer’s disease.