Interaction with polyglutamine aggregates reveals a Q/N-rich domain in TDP-43.
The identification of pathologic TDP-43 aggregates in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration, followed by the discovery of dominantly inherited point mutations in TDP-43 in familial ALS, have been critical insights into the mechanism of these untreatable neurodegenerative diseases. However, the biochemical basis of TDP-43 aggregation and the mechanism of how mutations in TDP-43 lead to disease remain enigmatic. In efforts to understand how TDP-43 alters its cellular localization in response to proteotoxic stress, we found that TDP-43 is sequestered into polyglutamine aggregates. Furthermore, we found that binding to polyglutamine aggregates requires a previously uncharacterized glutamine/asparagine (Q/N)-rich region in the C-terminal domain of TDP-43. Sequestration into polyglutamine aggregates causes TDP-43 to be cleared from the nucleus and become detergent-insoluble. Finally, we observed that sequestration into polyglutamine aggregates led to loss of TDP-43-mediated splicing in the nucleus and that polyglutamine toxicity could be partially rescued by increasing expression of TDP-43. These data indicate pathologic sequestration into polyglutamine aggregates, and loss of nuclear TDP-43 function may play an unexpected role in polyglutamine disease pathogenesis. Furthermore, as Q/N domains have a strong tendency to self-aggregate and in some cases can function as prions, the identification of a Q/N domain in TDP-43 has important implications for the mechanism of pathologic aggregation of TDP-43 in ALS and other neurodegenerative diseases.
Fuentealba
Rodrigo A
RA
Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Udan
Maria
M
Bell
Shaughn
S
Wegorzewska
Iga
I
Shao
Jieya
J
Diamond
Marc I
MI
Weihl
Conrad C
CC
Baloh
Robert H
RH
D000690:Amyotrophic Lateral Sclerosis / Q000209:etiology*; D001216:Asparagine; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine; D006801:Humans; D046912:Multiprotein Complexes; D010455:Peptides / Q000378:metabolism*; D055503:Protein Multimerization
D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D010455:Peptides; D005973:Glutamine; C097188:polyglutamine; D001216:Asparagine