Live-cell imaging reveals divergent intracellular dynamics of polyglutamine disease proteins and supports a sequestration model of pathogenesis.
Protein misfolding and aggregation are central features of the polyglutamine neurodegenerative disorders, but the dynamic properties of expanded polyglutamine proteins are poorly understood. Here, we use fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) with green fluorescent protein fusion proteins to study polyglutamine protein kinetics in living cells. Our results reveal markedly divergent mobility states for an expanded polyglutamine protein, ataxin-3, and establish that nuclear inclusions formed by this protein are aggregates. Additional studies of green fluorescent protein-tagged cAMP response element binding protein coexpressed with either of two mutant polyglutamine proteins, ataxin-3 and huntingtin, support a model of disease in which coaggregation of transcriptional components contributes to pathogenesis. Finally, studies of a third polyglutamine disease protein, ataxin-1, reveal unexpected heterogeneity in the dynamics of inclusions formed by different disease proteins, a finding which may help explain disease-specific elements of pathogenesis in these neurodegenerative disorders.
Chai
Yaohui
Y
Department of Neurology, 3160 Medical Labs, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
Shao
Jianqiang
J
Miller
Victor M
VM
Williams
Aislinn
A
Paulson
Henry L
HL
D000818:Animals; D000067699:Ataxin-3; D019556:COS Cells; D050882:CREB-Binding Protein; D049452:Green Fluorescent Proteins; D020271:Heredodegenerative Disorders, Nervous System / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008959:Models, Neurological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010455:Peptides / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection; D018911:Trinucleotide Repeats
D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D049452:Green Fluorescent Proteins; C097188:polyglutamine; D050882:CREB-Binding Protein; C092341:ATXN3 protein, human; D000067699:Ataxin-3