Expression of chondroitin sulfate and keratan sulfate proteoglycans in the path of growing retinal axons in the developing chick

Abstract

Previous investigations have identified proteoglycans in the central nervous system during development and have implicated some proteoglycans as axon guidance molecules that act by inhibiting axon extension. The present study investigated the pattern of immunoreactivity for several glycosaminoglycans common to certain proteoglycans relative to growing retinal axons in the developing chick visual system and in retinal explant cultures. Immunostaining for chondroitin-6-sulfate, chondroitin-4-sulfate, and keratan sulfate was observed to colocalize with retinal axons throughout the retinofugal pathway during the entire period of retinal axon growth. The proteoglycan form of collagen IX, however, was only observed in the retina, primarily peripheral to the areas with actively growing axons. The pattern of immunostaining for chondroitin sulfate in tissue sections suggested that the retinal axons might be a source for some of the chondroitin sulfate immunostaining in the developing visual pathway. This was confirmed in that chondroitin sulfate immunostaining was also observed on neurites emanating from cultured retinal explants. These findings indicate that retinal axons grow in the presence of chondroitin sulfate and keratan sulfate proteoglycans and that these proteoglycans in the developing chick visual pathway have functions other than to inhibit axon growth.

Disruption of gradient expression of Zic3 resulted in abnormal intra-retinal axon projection

“…Graded expression of attractants or repellents inside the retina is thus likely to be part of the mechanism that underlies the centrally directed retinal axon projection. Although our result is consistent with the previous findings that staining of CS-56 antibody persists in the center of the retina in chicken (McAdams and McLoon, 1995;Ring et al, 1995), we cannot rule out that a particular constituent of the CSPGs may still be involved in intraretinal axon targeting or subjected to the regulation by Zic3. The identities of the core proteins of the CSPGs have remained undefined.…”

“…10A,B). Similar to previous reports (McAdams and McLoon, 1995;Ring et al, 1995), we also observed that the staining of an anti-chondroitin sulfate proteoglycans (CSPGs) antibody (CS-56) persists in the center of the retina in chicken, albeit at a much lower level than in the periphery. This suggests that CSPGs may colocalize with the growing optic axons and play a different role in retinal axon guidance.…”

“…The CSPGs recognized by a monoclonal antibody CS-56 are expressed in a gradient in the rat retina, low in the center and high in the periphery (Brittis et al, 1992). However, the distribution of CSPGs in the retina of chick, quail and cat embryos has been shown to colocalize with the growing optic axons, suggesting a different role in retinal axon guidance (McAdams and McLoon, 1995;Ring et al, 1995). Axonal growth toward the optic fissure also requires expression of cell adhesion molecules (CAM) of the immunoglobulin superfamily like L1, neural cell adhesion molecule (NCAM) and neurolin (DM-GRASP).…”

Slit Proteins Regulate Distinct Aspects of Retinal Ganglion Cell Axon Guidance within Dorsal and Ventral Retina

“…These displaced or disorganized axons ultimately exit the optic disc. D, Dorsal; V, ventral. located in regions in which RGCs extend actively (McAdams and McLoon, 1995;Ring et al, 1995). Together, this suggests that fundamentally distinct mechanisms may regulate intraretinal axon guidance in the mammalian and chick retina.…”

Relationship between sprouting axons, proteoglycans and glial cells following unilateral nigrostriatal axotomy in the adult rat

“…For example, CSPGs are present in boundary and guidance regions during development and are usually growth inhibitory (Asher et al, 2000b). KSPGs are also present in boundary and guidance structures in development (Snow et al, 1990b;Geisert et al, 1992;Geisert and Bidanset, 1993;Gonzalez et al, 1993;McAdams and McLoon, 1995) although these have variable e¡ects upon neurite growth in vitro (Snow et al, 1990a;. In contrast, developmental studies (Halfter, 1993) and cell culture experiments (Wang and Denburg, 1992;Faissner et al, 1994;Walz et al, 1997) indicate that HSPGs are often growth-permissive molecules.…”