Identification of Neurite Outgrowth-promoting Domains of Neuroglycan C, a Brain-specific Chondroitin Sulfate Proteoglycan, and Involvement of Phosphatidylinositol 3-Kinase and Protein Kinase C Signaling Pathways in Neuritogenesis

Keiko Nakanishi,Sachiko Aono,Kanako Hirano,Yoshiyuki Kuroda,Michiru Ida,Yoshihito Tokita,Fumiko Matsui,Atsuhiko Oohira

doi:10.1074/jbc.m601498200

Keiko Nakanishi, Sachiko Aono + Show 6 more

Open Access

https://doi.org/10.1074/jbc.m601498200

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Abstract

Neuroglycan C (NGC) is a transmembrane-type chondroitin sulfate proteoglycan that is exclusively expressed in the central nervous system. We report that the recombinant ectodomain of NGC core protein enhances neurite outgrowth from rat neocortical neurons in culture. Both protein kinase C (PKC) inhibitors and phosphatidylinositol 3-kinase (PI3K) inhibitors attenuated the NGC-mediated neurite outgrowth in a dose-dependent manner, suggesting that NGC promotes neurite outgrowth via PI3K and PKC pathways. The active sites of NGC for neurite outgrowth existed in the epidermal growth factor (EGF)-like domain and acidic amino acid (AA)-domain of the NGC ectodomain. The EGF-domain caused cells to extend preferentially one neurite from a soma, whereas the AA-domain caused several neurites to develop. The EGF-domain also enhanced neurite outgrowth from GABA-positive neurons, but the AA-domain did not. These results suggest that the EGF-domain and AA-domain have distinct functions in terms of neuritogenesis. From these findings, NGC can be considered to be involved in neuritogenesis in the developing central nervous system.

Highlights

Tral nervous system (CNS), there are many PG species, some of which are classified into families with a domain structure common to their core proteins
We found that the epidermal growth factor (EGF)-domain and amino acid (AA)-domain of the Neuroglycan C (NGC) ectodomain enhanced the outgrowth of neurites from rat neocortical neurons, and that NGC-induced neurite outgrowth was mediated via phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) pathways
The fact that a higher dose (5–10 ␮M) of bisindolylmaleimide I was required for the inhibition of NGC-induced neurite outgrowth suggests the binant ectodomain of the NGC core protein promotes neurite involvement of aPKCs rather than cPKCs and nPKCs

Summary

Introduction

Tral nervous system (CNS), there are many PG species, some of which are classified into families with a domain structure common to their core proteins (for review, see Ref. 1). Twenty-four hours after plating, the neurites of neurons cultured in the presence of NGCect (50 ␮g/ml) were longer than those of control cells cultured without any NGC peptides (None) or with only GST (Fig. 2A).

Results

Conclusion