Chapter 15 Boundary molecules during brain development, injury, and persistent neurogenesis - in vivo and in vitro studies

Publisher Summary In this chapter, three model systems have been described that exemplify the presence and potential biological functions of boundary extracellular matrix (ECM) molecules. Even though these developmentally regulated proteins, sometimes referred to as recognition molecules, are often uniformly expressed in low-levels throughout the developing neuraxis, their dense concentration in so-called boundary regions alerted to their possible functions as interfaces between different brain structures or units. This cordone hypothesis is also consistent with the observed upregulation of boundary molecules in association with the glial scar, and bioassays of such molecules in the astroglial scar reveal their complex interactions with numerous other molecules that can both encourage or deter neuronal adhesion and neurite growth. The persistent expression of boundary ECM molecules in the neurogenic subependymal zone (SEZ) may prove to be the most insightful model for studying the many roles of these molecules. Because cells are born, migrate, and die in relation to an enhanced ECM expression in vivo in the rostral migratory stream, as well as the inferred role of ECM in the generation of novel proliferative spheres in vitro , future studies need to focus on the patterns of gene expression of SEZ-derived stem and precursor cells in relation to ECM expression in order to establish their roles during the proliferation and specification of neurons and glia.