The extracellular matrix in development and morphogenesis: a dynamic view

Abstract

The extracellular matrix (ECM) is synthesized and secreted by embryonic cells beginning at the earliest stages of development. Our understanding of ECM composition, structure and function has grown considerably in the last several decades and this knowledge has revealed that the extracellular microenvironment is critically important for cell growth, survival, differentiation and morphogenesis. ECM and the cellular receptors that interact with it mediate both physical linkages with the cytoskeleton and the bidirectional flow of information between the extracellular and intracellular compartments. This review considers the range of cell and tissue functions attributed to ECM molecules and summarizes recent findings specific to key developmental processes. The importance of ECM as a dynamic repository for growth factors is highlighted along with more recent studies implicating the 3-dimensional organization and physical properties of the ECM as it relates to cell signaling and the regulation of morphogenetic cell behaviors. Embryonic cell and tissue generated forces and mechanical signals arising from ECM adhesion represent emerging areas of interest in this field.

Figure 1

Summary of ECM functions in development. The ECM is multi-functional and can influence multiple biochemical and mechanical processes simultaneously. This figure illustrates different functional states of the ECM and their biological contexts. The five categories are not mutually exclusive. When interpreting ECM loss-of-function phenotypes, one should consider that multiple processes may be compromised thus specific roles of individual ECM components are difficult to glean. A couple of important properties of ECM are not illustrated in this cartoon. First, ECMs are highly dynamic and can be modified by the cells that come into contact with them creating a bi-directional mode of cell-matrix communication. Second, ECM-ECM interactions vary the chemical and mechanical composition of the extracellular microenvironment. In this review, we incorporate several examples of how the functions of ECM are utilized during embryonic development.