HNK-1 (human natural killer-1) glyco-epitope, a sulfated glucuronic acid attached to N-acetyllactosamine on the nonreducing termini of glycans, is highly expressed in the nervous system. Our previous report showed that mice lacking a glucuronyltransferase (GlcAT-P), a key enzyme for biosynthesis of the HNK-1 epitope, showed reduced long term potentiation at hippocampal CA1 synapses. In this study, we identified an α-amino-3-hydroxy-5-methylisoxazole propionate (AMPA)-type glutamate receptor subunit, GluR2, which directly contributes to excitatory synaptic transmission and synaptic plasticity, as a novel HNK-1 carrier molecule. We demonstrated that the HNK-1 epitope is specifically expressed on the N-linked glycan(s) on GluR2 among the glutamate receptors tested, and the glycan structure, including HNK-1 on GluR2, was determined using liquid chromatography-tandem mass spectrometry. As for the function of HNK-1 on GluR2, we found that the GluR2 not carrying HNK-1 was dramatically endocytosed and expressed less on the cell surface compared with GluR2 carrying HNK-1 in both cultured hippocampal neurons and heterologous cells. These results suggest that HNK-1 stabilizes GluR2 on neuronal surface membranes and regulates the number of surface AMPA receptors. Moreover, we showed that the expression of the HNK-1 epitope enhanced the interaction between GluR2 and N-cadherin, which has important roles in AMPA receptor trafficking. Our findings suggest that the HNK-1 epitope on GluR2 regulates cell surface stability of GluR2 by modulating the interaction with N-cadherin.
HNK-1 Glyco-epitope Regulates the Stability of the Glutamate Receptor Subunit GluR2 on the Neuronal Cell Surface*
Ippei Morita,S. Kakuda,Y. Takeuchi,S. Itoh,N. Kawasaki,Yasuhiko Kizuka,T. Kawasaki,S. Oka
Published 2009 in Journal of Biological Chemistry
ABSTRACT
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- Publication year
2009
- Venue
Journal of Biological Chemistry
- Publication date
2009-09-03
- Fields of study
Biology, Medicine
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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