ABSTRACT
The structure and function of the nervous system is highly dependent on cellular interactions. Indeed, the fundamental unit of brain function, the synapse, is actually a highly specialized example of cell adhesion. Because the function of the adult brain is dependent predominantly on the immensely complex, yet precise geometric network of neurons, its development relies heavily on accurate control of the migration of neurons and their axons, both of which require exquisite regulation of cell-cell and cell-substrate interactions. In other words, both developmental and physiological aspects of the nervous system are heavily dependent on cellular interactions. Interestingly, nervous tissues have a peculiar repertoire of extracellular matrix (ECM) components, abundant in various types of proteoglycans while lacking most of common ECM proteins such as collagens and fibronectin. Thus it is expected that proteoglycans might play substantial roles in the nervous system. Work done during the past decade has validated this expectation. The nervous system has become one of the most attractive systems among all organs and tissues in studying the functions of proteoglycans. There is now a wealth of data showing that proteoglycans indeed play important roles in the nervous system. Here I review the historical background and recent progress in understanding the function of one of the major classes of proteoglycans, chondroitin sulfate proteoglycans (CSPGs).
