Extracellular Matrix (ECM) Molecules

Abstract The extracellular matrix (ECM) is a dynamic, heterogeneous, three-dimensional suprastructure that anchors and surrounds cellular compartments in tissues and organs. The ECM is essentially composed of four components: collagens; elastin; glycoproteins; and proteoglycans that undergo tissue-specific post-translational modifications and cell-mediated hierarchical assembly to generate macromolecular structures whose biomechanical and biophysical properties range from a pliable translucent hydrogel to rock-hard mineralized tissue. The ECM molecules and their respective assemblies provide a structural and instructive scaffold during development and throughout life, that endows tissues with tensile strength, elasticity, hydration, and the ability to withstand mechanical forces. The coupling of ECM proteins to the intracellular cytoskeleton through cell surface receptors alters the cellular genetic machinery in response to external biomechanical cues. Moreover, the ECM molecules function as a repository for growth factors, cytokines, and proteinases. The spatio-temporal release of these soluble ECM components, and their subsequent cell signaling cascades, modulate ECM turnover and fundamental cellular processes including differentiation, proliferation, migration, and survival. The ECM is a major determinant of cell fate and survival, and its importance is underscored by the multitude of acquired and hereditary disorders associated with the defects in synthesis, secretion, and/or assembly of ECM proteins. Alterations in the structural and functional properties of the ECM molecules are also underlying causes for derailed wound healing and angiogenesis, cancer metastasis, and other disease states.