Isolation of a neural chondroitin sulfate proteoglycan with neurite outgrowth promoting properties.

Abstract

Abstract. Proteoglycans are expressed in various tissues on cell surfaces and in the extracellular matrix and display substantial heterogeneity of both protein and carbohydrate constituents. The functions of individual proteoglycans of the nervous system are not well characterized, partly because specific reagents which would permit their isolation are missing. We report here that the monoclonal antibody 473HD, which binds to the surface of early differentiation stages of murine astrocytes and oligodendrocytes, reacts with the chondroitin sulfate/dermatan sulfate hybrid epitope DSD-1 expressed on a central nervous system chondroitin sulfate proteoglycan designated DSD-1-PG. When purified from detergent-free postnatal days 7 to 14 mouse brain extracts, DSD-1-PG displays an apparent molecular mass between 800-1,000 kD with a prominent core glycoprotein of 350-400 kD. Polyclonal anti-DSD-1-PG antibodies and monoclonal antibody 473HD react with the same molecular species as shown by immunocytochemistry and sequential immunoprecipitation performed on postnatal mouse cerebellar cultures, suggesting that the DSD-1 epitope is restricted to one proteoglycan. DSD-1-PG promotes neurite outgrowth of embryonic day 14 mesencephalic and embryonic day 18 hippocampal neurons from rat, a process which can be blocked by monoclonal antibody 473HD and by enzymatic removal of the DSD-1-epitope. These results show that the hybrid glycosaminoglycan structure DSD-1 supports the morphological differentiation of central nervous system neurons.

Conformational Studies on Five Octasaccharides Isolated from Chondroitin Sulfate Using NMR Spectroscopy and Molecular Modeling

“…MAb 473HD recognizes structures containing at least one A-D or D-A tetrasaccharide unit (17). As indicated already, this antibody recognizes a unique CS epitope in DSD-1-PG (phosphacan), which is an ectodomain of the signal transducing receptor-like protein tyrosine phosphatase PTP / RPTP (11). The epitope appears to contain L-iduronic acid (IdoA) as well, since it is eliminated by chondroitinase ABC but not by chondroitinase ACII (11).…”

“…Chondroitinase ABC degrades CS via a -eliminative cleavage at internal GlcA residues, yielding ∆ 4,5 HexA-containing oligosaccharides (∆ 4,5 HexA ) 4-deoxy-L-threo-hex-4-enopyranuronic acid) (10). The CS-PG named DSD-1-PG, located on the surface of immature glial cells in the CNS in developing mouse brain, promotes neurite outgrowth (11). The disulfated disaccharide D [GlcA2S( 1-3)GalNAc6S] (Figure 1), being the major component in shark cartilage CS-D, is also present in some neurotrophic CS-PGs such as DSD-1-PG (12).…”

Molecular Cloning and Characterization of Chondroitin-4-O-sulfotransferase-3

“…The highly regulated expression of GalNAc-4-ST1 (3,30) in other tissues such as the brain suggests that it will have additional roles that remain to be defined. In addition to their importance for the formation and maintenance of cartilage (31,32), there is also evidence that chondroitin sulfate proteoglycans are important for neural cell adhesion, neurite outgrowth, synaptic plasticity, and regeneration (33)(34)(35)(36)(37). A number of chondroitin sulfate-bearing proteoglycans are produced by tissues (31,32).…”

Modulators of axonal growth and guidance at the brain midline with special reference to glial heparan sulfate proteoglycans

“…Interestingly, RPTPβ/ phosphacan is also found in certain locations during development such as the roof plate (Meyer-Puttlitz et al 1996), a structure that axons avoid for an extended developmental period (Smith 1983, Orlino et al 2000, in apparent contradiction to an induction of neurite outgrowth through contactin and Nr-CAM. Sakurai and coworkers (1997) remarked that such a discrepancy was due to the roof plate of the spinal cord being deficient in adhesion molecules in general while the fiber tracts have a rich assortment of CAMs (see also Faissner et al 1994, Garwood et al1999). Therefore, it is likely that RPTPβ/ phosphacan differentially affects neurite growth depending on the relative abundance of the different forms of the molecule.…”

“…CD44 has 10 or more different isoforms, with variable abilities to bind HA or heparan sulfate (Piepkorn et al 1999). Other secreted PGs are the keratancontaining and keratan-devoid variants of the soluble form of RPTPδ phosphatase or phosphacan and its mouse homologue DSD1 (Faissner et al 1994, Garwood et al 1999). In the developing mammalian brain, aggrecan family proteoglycans, phosphacan/RPTPβ/ξ , and neuroglycan C (NGC) are the major classes of chondroitin sulfate proteoglycans .…”