Type II Collagen (Col2a1) in Axial Skeletal Formation of Lizard Tail
Chondrocytes express chondrocyte-specific extracellular matrix proteins such as type II, IX, XI collagens and aggrecan, while the hypertrophic chondrocytes tend to produce matrix high in type I and X collagens (Cancedda et al., 1995; Erlebacher et al., 1995; Hall & Miyake, 1995; Niu et al., 2016). Type II collagen is encoded by the type II procollagen gene (Col2a1) (Hering et al., 2014; Cruet-Hennequart et al., 2015) and its expression is usually used as an early key marker of chondrogenic cells (Mori-Akiyama et al., 2003; Xu et al., 2008). In mouse embryo, Sox9 is co-expressed with Col2a1, suggesting that direct activation of Col2a1 by Sox9 is crucial in activating genes that encode cartilage extracellular matrix proteins (Lefebvre & de Crombrugghe, 1998; Lefebvre et al., 1998; Grogan et al., 2008). Chondrocytes begin to synthesize type II collagen in the form of a procollagen molecule with a triple-helical α1 (II) chains. This procollagen molecule has an amino and carboxyl pr...