Foxc1 establishes enhancer accessibility for craniofacial cartilage differentiation.

When our bodies form cartilage, a key player is a protein called Sox9, which is involved in various processes beyond just making bones. But how Sox9 and other important factors actually get to the right places in our skeleton during development has been a mystery. In a study using zebrafish, scientists examined how specific parts of DNA that are associated with cartilage become accessible during the development of cartilage-producing cells. They discovered that these regions of DNA become available for use at different times. Interestingly, the regions that become active after certain cells have already moved to where they're needed in the body have specific signals for Sox9 and a group of proteins called Fox. In zebrafish that were missing certain Fox proteins, there was a decrease in the availability of these DNA regions in cartilage-producing cells. This change seemed to affect the development of facial cartilages in these fish, leading to the loss of certain parts of the face. Further experiments in zebrafish confirmed that many of these Fox-dependent DNA regions play a role in boosting the activity of genes in specific parts of facial cartilages at different stages of development. In summary, this study reveals that a group of proteins, including Fox, helps make sure that the right genes are accessible for building cartilage in the face. Understanding this process could be important for improving our knowledge of skeletal development and potential future therapies.