title: Expression of polyglutamine-expanded huntingtin induces tyrosine phosphorylation of N-methyl-D-aspartate receptors.
abstract: In our previous studies, we found that expression of polyglutamine-expanded huntingtin in HN33 cells induced sensitization of N-methyl-D-aspartate (NMDA) receptors (Sun, Y., Savinainen, A., and Liu, Y. F. (2001) J. Biol. Chem. 276, 24713-24718). Following this study, we investigated whether tyrosine phosphorylation of NMDA receptors might contribute to the altered property of the receptors. Expression of polyglutamine-expanded huntingtin induced elevation of phosphorylated or activated Src and increased targeting of PSD-95 (post-synaptic density 95) and activated Src to cell surface membrane. Expression of the mutated huntingtin also induced tyrosine phosphorylation of NR2B (NMDA receptor 2B) subunits, and co-expression of PSD-95 enhanced the phosphorylation. Treatment of SU6656 (a specific Src inhibitor) or co-expression of a mutated NR2B subunit with mutations of all three major tyrosine phosphorylation sites significantly attenuated neuronal toxicity induced by the mutated huntingtin. Addition of AP-5 did not further inhibit the neuronal toxicity. Taken together, our studies show that polyglutamine-expanded huntingtin increases tyrosine phosphorylation of NMDA receptors via PSD-95 and Src, and increased tyrosine phosphorylation may contribute to the sensitization of the receptors mediated by polyglutamine-expanded huntingtin.
authors.affiliation: Department of Pharmacology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Song
authors.forename: Yuntian
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chris G
authors.initials: CG
authors.lastname: Parsons
authors.forename: Ya Fang
authors.initials: YF
authors.lastname: Liu
mesh_terms: D016923:Cell Death; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D000071058:Huntingtin Protein; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008856:Microscopy, Fluorescence; D009154:Mutation; D016202:N-Methylaspartate / Q000737:chemistry; D009419:Nerve Tissue Proteins / Q000737:chemistry*; D009687:Nuclear Proteins / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D016194:Receptors, N-Methyl-D-Aspartate; C033652:postsynaptic density proteins; C097188:polyglutamine; D014443:Tyrosine; D016202:N-Methylaspartate