Chapter 1 - Structure, Biosynthesis and Gene Regulation of Collagens in Cartilage and Bone

Abstract

This chapter provides an overview on the structural and functional features of cartilage and bone collagens, and their interactions with other matrix proteins and cell receptors. It summarizes the various steps of collagen biosynthesis and post-translational modifications, and provides an overview of the collagen genes and their cis-acting regulatory element. How these are regulated by growth factors, cytokines, hormones, and transcription factors is one of the current challenges to understand the dynamics of connective tissue turnover and homostasis. In bones, densely packed and intensely cross-linked heterofibrils of type I and V collagen provide the architectural scaffold and substrate for mineralization; and thus, hold responsibility for the enormous resistance of bone to mechanical load, torsion, and tension. In hyaline cartilage, heterofibrils of collagen type II and XI, decorated with FACIT collagens, assemble into cross-linked meshwork, which allow the incorporation of highly hydrated hyaluronan–proteoglycan complexes, thus, providing the tissue with elasticity combined with high resistance to pressure. The role of collagens in bone and cartilage was introduced by biological cell and transgenic mouse experiments, showing that collagens transmit—on top of their biomechanical function—specific information to cells by providing substrates for cell adhesion, proliferation, migration, arrangement in the tissue, differentiation, gene expression, or cell survival.