PMID:12514214

Citation	Ughrin, YM, Chen, ZJ and Levine, JM (2003) Multiple regions of the NG2 proteoglycan inhibit neurite growth and induce growth cone collapse. J. Neurosci. 23:175-86
Abstract	The NG2 chondroitin sulfate proteoglycan, an integral membrane proteoglycan, inhibits axon growth from cerebellar granule neurons and dorsal root ganglia (DRG) neurons in vitro. The extracellular domain of the NG2 core protein contains three subdomains: an N-terminal globular domain (domain 1), a central extended domain that has the sites for glycosaminoglycan (GAG) attachment (domain 2), and a juxtamembrane domain (domain 3). Here, we used domain-specific fusion proteins and antibodies to map the inhibitory activity within the NG2 core protein. Fusion proteins encoding domain 1 (D1-Fc) or domain 3 (D3-Fc) of NG2 inhibited axon growth from cerebellar granule neurons when the proteins were substrate-bound. These proteins also induced growth cone collapse from newborn DRG neurons when added to the culture medium. Domain 2 only inhibited axon growth when the GAG chains were present. Neutralizing antibodies directed against domain 1 or 3 blocked completely the inhibition from substrates coated with D1-Fc or D3-Fc. When the entire extracellular domain of NG2 was used as a substrate, however, both neutralizing antibodies were needed to reverse completely the inhibition. When NG2 was expressed on the surface of HEK293 cells, the neutralizing anti-D1 antibody was sufficient to block the inhibition, whereas the anti-D3 antibody had no effect. These results suggest that domains 1 and 3 of NG2 can inhibit neurite growth independently. These inhibitory domains may be differentially exposed depending on whether NG2 is presented as an integral membrane protein or as a secreted protein associated with the extracellular matrix.
Links	PubMed
Keywords	Animals; Antibodies, Monoclonal/immunology; Antibodies, Monoclonal/pharmacology; Antigens/chemistry; Antigens/genetics; Antigens/physiology; COS Cells; Cell Line; Cells, Cultured; Cerebellum/cytology; Cerebellum/growth & development; Ganglia, Spinal/cytology; Growth Cones/ultrastructure; Humans; Membrane Glycoproteins/chemistry; Membrane Glycoproteins/physiology; Neurites/ultrastructure; Protein Structure, Tertiary; Proteoglycans/chemistry; Proteoglycans/genetics; Proteoglycans/physiology; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins/analysis; Recombinant Fusion Proteins/pharmacology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RAT:CSPG4	part_of	GO:0005887: integral component of plasma membrane	ECO:0000304: author statement supported by traceable reference used in manual assertion		C		Seeded From UniProt	complete

References

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