Chondroitin sulfate proteoglycan expression pattern in hippocampal development: Potential regulation of axon tract formation

Abstract

A variety of molecular influences in the extracellular matrix (ECM) interact with developing axons to guide the formation of hippocampal axon pathways. One of these influences may be chondroitin sulfate proteoglycans (CSPGs), which are known to inhibit axonal extension during development and following central nervous system injury. In this study, we examined the role of CSPGs and cell adhesion molecules in the regulation of axon tract formation during hippocampal development. We used indirect immunofluorescence to examine the developmental pattern of CSPG expression relative to axon tracts that express the cell adhesion molecule L1. Additionally, we used dissociated and explant cell cultures to examine the effects of CSPGs on hippocampal axon development in vitro. In vivo, we found that the CSPG neurocan is expressed throughout the alveus, neuropil layers, and parts of the dentate gyrus from E16 to P2. The CSPG phosphacan is expressed primarily in the neuropil layers at postnatal stages. After E18, intense labeling of neurocan was observed in regions of the alveus surrounding L1-expressing axon fascicles. In vitro, axons from brain regions that project through the alveus during development would not grow across CSPG substrata, in a concentration-dependent manner. In addition, hippocampal axons from dissociated neuron cultures only traveled across CSPG substrata as fasciculated axon bundles. These findings implicate CSPG in the regulation of axon trajectory and fasciculation during hippocampal axon tract formation.

Chondroitin Sulfate Proteoglycan Tenascin-R Regulates Glutamate Uptake by Adult Brain Astrocytes

“…After fixation with 1% glutaraldehyde at 4°C for 10 min, the sections were washed with 50 mM Tris-HCl (pH 7.4) containing 0.15 M NaCl and then incubated with 3,3Ј-diaminobenzidine tetrachloride and 0.05% H 2 O 2 . The sections were fixed with 2% OsO 4 , and the sections were dehydrated in propylene oxide after going through the alcohol series and embedded in epoxy resin (Oken, Tokyo, Japan). Ultrathin sections were cut using an ultramicrotome (Leica Microsystems, Wetzlar, Germany), mounted on nickel mesh, stained with uranyl acetate, and observed using a JEM 1200EX electron microscope (JEOL, Tokyo, Japan).…”

“…Chondroitin sulfate proteoglycans (CSPGs) 2 are major components of the extracellular matrix in the brain and play significant roles in cell migration, neurite elongation, pathfinding, and synaptogenesis in the developing brain as well as regeneration and synaptic plasticity in the adult brain (1)(2)(3)(4). In the adult brain, CSPGs exhibit a unique distribution pattern, termed perineuronal nets (PNNs).…”

Cadherin‐8 and N‐cadherin differentially regulate pre‐ and postsynaptic development of the hippocampal mossy fiber pathway

“…Some innervation of the pyramidal cell layer occurs normally over the course of development, but typically not to the degree observed following the manipulations described (Amaral, 1979;Amaral and Dent, 1981). The consistent direction of the misguided trajectories is likely to be driven by the intact inhibitory extracellular matrix and repulsive Sema6A activity in stratum radiatum (Wilson and Snow, 2000;Butler et al, 2004;Suto et al, 2007), coupled with a permissive or even attractive environment generated locally by the CA3 pyramidal cell layer (Steup et al, 2000). Distal CA3 mistargeting occurs in mice lacking NCAM (Cremer et al, 1997;Seki and Rutishauser, 1998), following enzymatic removal of keratan sulfate glycosaminoglycans, or following exposure to anti-LAMP antibodies, HAV or QAV peptides (Piment et al, 1995;Butler et al, 2004;present study).…”

Repellent Guidance of Regenerating Optic Axons by Chondroitin Sulfate Glycosaminoglycans in Zebrafish

“…Although in some systems, CSs appear to exclude axons, suggesting a repelling function for axons (Snow et al, 1990;Oakley and Tosney, 1991; for review, see Faissner and Steindler, 1995), in others, axons appear to prefer CS substrates (Bicknese et al, 1994;Faissner et al, 1994). In yet others, there is a complex distribution of CSs in the pathway of growing axons (Fernaud-Espinosa et al, 1996;Wilson and Snow, 2000), which led to the suggestion that CSs may anchor other molecules that guide axons in the extracellular matrix (Emerling and Lander, 1996). Finally, in vitro experiments indicate that reactions of developing axons to CSs depend on the mode by which the glycans are presented (soluble, homogeneous, or as a step gradient; Snow and Letourneau, 1992;Challacombe and Elam, 1997;Hynds and Snow, 1999), on the composition of CS side chains (Faissner et al, 1994;Braunewell et al, 1995;Clement et al, 1998;Nadanaka et al, 1998), and on the neuronal cell type analyzed (Snow and Letourneau, 1992;FernaudEspinosa et al, 1994;Dou and Levine, 1995).…”