Cystatin 10 (CST10)

Cystatin 10, a novel chondrocyte-specific protein, may promote the last steps of the chond. In the mouse chondrogenic cell line ATDC5, Cst10 expression preceded type X collagen expression and increased in synchrony with maturation. ATDC5 cells transfected with Cst10 cDNA with cells transfected with a mock vector, hypertrophic maturation and mineralization of chondrocytes were promoted by Cst10 gene overexpression in that type X collagen expression was observed earlier, and alizarin red staining was stronger. Overexpression of the Cst10 gene also caused fragmentation of nuclei, the appearance of annexin V, a change in the mitochondrial membrane potential, and activation of caspases. Cst10 may play an important role in the last steps of the chondrocyte differentiation pathway as an inducer of maturation, followed by apoptosis of chondrocytes.