Ubiquitin-interacting motifs inhibit aggregation of polyQ-expanded huntingtin.
Expansion of polyglutamine (polyQ) tracts within proteins underlies a number of neurodegenerative diseases, such as Huntington disease, Kennedy disease, and spinocerebellar ataxias. The resulting mutant proteins are unstable, forming insoluble aggregates that are associated with components of the ubiquitin system, including ubiquitin, ubiquitin-like proteins, and proteins that bind to ubiquitin. Given the presence of these ubiquitin-binding proteins in the insoluble aggregates, we examined whether heterologous expression of short motifs that bind ubiquitin, termed ubiquitin-interacting motifs (UIMs), altered the aggregation of polyQ-expanded huntingtin (Htt), the protein product of the Huntington disease gene. We found that a subset of UIMs associated with mutant Htt. The ability to interact with ubiquitin was necessary, but not sufficient, for interaction with mutant Htt. Furthermore, we found that expression of single, isolated UIMs inhibited aggregation of mutant Htt. These data suggest that isolated UIMs might serve as potential inhibitors of polyQ-aggregation in vivo.
Miller
Stephanie L H
SLH
Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709.
Scappini
Erica L
EL
Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709.
O'Bryan
John
J
Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709; Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612. Electronic address: obryanj@uic.edu.
D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D002460:Cell Line; D006801:Humans; D000071058:Huntingtin Protein; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000037:antagonists & inhibitors / Q000378:metabolism*
C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D025801:Ubiquitin; C097188:polyglutamine