Emerging functions of matricellular proteins

Abstract

Cells in multicellular organisms employ a variety of mechanisms to coordinate their individual functions with the needs to the whole. Over the past two decades, the extracellular matrix has become recognized as more than just a structural framework to arrange cells in the proper three-dimensional context to form tissues and organs. Many of the cell surface receptors for specific matrix components are signaling receptors, and their ligation alters signal transduction pathways that control cell shape, survival, movement, and gene expression [1]. Rigidity or elasticity of the matrix provides additional information that controls cell behavior through a process known as mechanotransduction [2]. Matrix proteins also contain binding sites for diffusible growth factors, and specific matrix components can be essential cofactors for presentation of growth factors to their signaling receptors [3]. Such binding sites in the matrix also provide a repository for storing growth factors in the matrix, which can limt their diffusion and allow gradients to be established that provide guidance cues for tissue morphogenesis and regeneration. Together, these signals from the extracellular matrix create a context that tells cells which differentiation programs to execute, identifies neighboring cells to each other, and creates permeability barriers that define what solutes and macromolecules can pass between cells.