Editing-defective tRNA synthetase causes protein misfolding and neurodegeneration.
Misfolded proteins are associated with several pathological conditions including neurodegeneration. Although some of these abnormally folded proteins result from mutations in genes encoding disease-associated proteins (for example, repeat-expansion diseases), more general mechanisms that lead to misfolded proteins in neurons remain largely unknown. Here we demonstrate that low levels of mischarged transfer RNAs (tRNAs) can lead to an intracellular accumulation of misfolded proteins in neurons. These accumulations are accompanied by upregulation of cytoplasmic protein chaperones and by induction of the unfolded protein response. We report that the mouse sticky mutation, which causes cerebellar Purkinje cell loss and ataxia, is a missense mutation in the editing domain of the alanyl-tRNA synthetase gene that compromises the proofreading activity of this enzyme during aminoacylation of tRNAs. These findings demonstrate that disruption of translational fidelity in terminally differentiated neurons leads to the accumulation of misfolded proteins and cell death, and provide a novel mechanism underlying neurodegeneration.
Lee
Jeong Woong
JW
The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA.
Beebe
Kirk
K
Nangle
Leslie A
LA
Jang
Jaeseon
J
Longo-Guess
Chantal M
CM
Cook
Susan A
SA
Davisson
Muriel T
MT
Sundberg
John P
JP
Schimmel
Paul
P
Ackerman
Susan L
SL
D000107:Acetylation; D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000412:Alanine-tRNA Ligase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D002384:Catalysis; D004926:Escherichia coli / Q000235:genetics; D005347:Fibroblasts; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019636:Neurodegenerative Diseases / Q000201:enzymology* / Q000235:genetics; D010641:Phenotype; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011689:Purkinje Cells / Q000378:metabolism / Q000473:pathology; D012344:RNA, Transfer, Ala / Q000235:genetics; D012694:Serine / Q000235:genetics / Q000378:metabolism
D012344:RNA, Transfer, Ala; D012694:Serine; D000412:Alanine-tRNA Ligase; D000409:Alanine