title: Mutant huntingtin protein: a substrate for transglutaminase 1, 2, and 3.
abstract: The most prominent neuropathologic hallmarks of Huntington disease (HD) are cortical and striatal perinuclear cytoplasmic aggregates and intranuclear inclusions of mutant huntingtin. Our laboratory previously demonstrated that huntingtin protein colocalizes with transglutaminase 2 and its product, the epsilon-(gamma-glutamyl)lysine bond in intranuclear inclusions in HD frontal cortex. We also found that transglutaminase 2 cross-links N-terminal fragments of mutant huntingtin (htt-N63-148Q-myc) in cells in culture. We now report a significant increase in transglutaminase 2 mRNA in HD cortex (225% of controls) and striatum (399% of controls). Expression of the short transglutaminase 2 mRNA splice variant was not detectable in HD, although previous studies demonstrated upregulation in Alzheimer disease and progressive supranuclear palsy. Cells co-transfected with GFP-tagged transglutaminase 1, 2, or 3 and htt-N63-148Q-myc exhibit increased cross-linked huntingtin in the insoluble fraction of cell lysates. Treatment of cells with cystamine, a chemical inhibitor of transglutaminase, decreased aggregated and cross-linked huntingtin and increased viability of cells that were transfected with transglutaminase 2 and htt-N63-148Q-myc. These data suggest that transglutaminase 1, 2, and 3 could be involved in cross-linking of huntingtin into intranuclear inclusions in HD and that inhibiting transglutaminase should be explored as a potential treatment strategy for HD.
authors.affiliation: Department of Pharmacology, 2160 S. First Avenue, Maywood, IL 60153, USA.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Zainelli
authors.forename: Nichole L
authors.initials: NL
authors.lastname: Dudek
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Ross
authors.forename: Soo-Youl
authors.initials: SY
authors.lastname: Kim
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Muma
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing / Q000235:genetics; D001921:Brain / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003432:Cross-Linking Reagents / Q000378:metabolism; D003538:Cystamine / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000201:enzymology* / Q000235:genetics*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D013379:Substrate Specificity / Q000235:genetics; D014162:Transfection / Q000379:methods; D011503:Transglutaminases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D002135:Calcium-Binding Proteins; D003432:Cross-Linking Reagents; C086055:HTT protein, human; D000071058:Huntingtin Protein; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D000091345:Protein Glutamine gamma Glutamyltransferase 2; C498712:TGM3 protein, human; D011503:Transglutaminases; C105804:transglutaminase 1; D019204:GTP-Binding Proteins; D003538:Cystamine