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Title
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Functional complementation in Drosophila to predict the pathogenicity of TARDBP variants : evidence for a loss-of-function mechanism
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Author
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Abstract
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| The human TAR DNA binding protein 43 (TDP-43), encoded by the gene TARDBP, plays a central role in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. TDP-43 inclusions are also found in up to approximately 60% of Alzheimer's disease (AD) brains. Although ALS-causing TARDBP mutations cluster in the C-terminal glycine-rich region of the protein, the pathogenic nature of the atypical missense variants p.A90V (located between the bipartite nuclear localization signal) and p.D169G (located in the first RNA-binding domain) is unclear. In addition, whether causal ALS mutations represent gain or loss-of-function alleles remains unknown. We recently reported that loss-of-function of the highly conserved TARDBP ortholog in Drosophila (called TBPH) leads to death of bursicon neurons resulting in adult maturation and wing expansion defects. Here, we compared wild-type TARDBP, 2 typical ALS-causing mutations (p.G287S and p.A315T) and 2 atypical variants (p.A90V and p.D169G), for their ability to complement neuronal TBPH loss-of-function. Although p.D169G rescued organismal pupal lethality and neuronal loss to a similar extent as wild-type TARDBP, p.A90V, p.G287S, and p.A315T were less efficient. Accordingly, p.A90V, p.G287S, and p.A315T but not p.D169G or wild-type protein promoted a shift of TDP-43 from the nucleus to the cytoplasm in approximately 12%14% of bursicon neurons. Finally, we found that the carrier frequency of rare variant p.A90V was higher in French-Belgian AD cases (5/1714, 0.29%) than in controls of European descent (5/9436, 0.05%) (odds ratio = 5.5; 95% confidence interval, 1.619.0; p = 0.009). We propose that pathogenic TARDBP mutations have partial loss-of-function properties and that TARDBP p.A90V may increase AD risk by the same mechanism. |
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Language
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English
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Source (journal)
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Neurobiology of aging. - Fayetteville, N.Y.
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Publication
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Fayetteville, N.Y.
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2015
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ISSN
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0197-4580
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DOI
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10.1016/J.NEUROBIOLAGING.2014.09.001
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Volume/pages
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36
:2
(2015)
, p. 1121-1129
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ISI
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000352454400058
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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