Abstract |
Amyotrophic lateral sclerosis and frontotemporal lobar degeneration are neurodegenerative diseases characterized by accumulation of insoluble aggregates of phosphorylated 43 kDa TAR DNA-binding protein (TDP-43) and linked with abnormal expansion of a hexanucleotide repeat in an intron of chromosome 9 open reading frame 72 (C9ORF72). However, the relationship between C9ORF72 mutations and TDP-43 aggregation remains unknown. Non-ATG-dependent translation of C9ORF72 repeats produces dipeptide repeat proteins, which form p62-positive aggregates in cerebral cortex and cerebellum of patients. Here, we show that the formation of poly-GA protein inclusions induced intracellular aggregation of endogenous and exogenous TDP-43 in cultured cells. Poly-GA aggregation preceded accumulation of phosphorylated TDP-43. These inclusions induced intracellular aggregation of phosphorylated TDP-43, but not tau or α- synuclein. Formation of phosphorylated TDP-43 aggregates depends on the number of poly-GA repeats. Detergent-insoluble fraction from cells co-expressing poly-GA and TDP-43 could function as seeds for further TDP-43 aggregation. These findings suggest a novel pathogenic mechanism that poly-GA protein aggregation directly promotes pathogenic changes of TDP-43 without the formation of nuclear RNA foci containing GGGGCC repeat expansion or loss-of-function of the C9ORF72 protein.
|
Authors | Takashi Nonaka, Masami Masuda-Suzukake, Masato Hosokawa, Aki Shimozawa, Shinobu Hirai, Haruo Okado, Masato Hasegawa |
Journal | Human molecular genetics
(Hum Mol Genet)
Vol. 27
Issue 15
Pg. 2658-2670
(08 01 2018)
ISSN: 1460-2083 [Electronic] England |
PMID | 29750243
(Publication Type: Journal Article)
|
Copyright | © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For permissions, please email: [email protected]. |
Chemical References |
- C9orf72 Protein
- C9orf72 protein, human
- DNA-Binding Proteins
- Dipeptides
- TARDBP protein, human
- alpha-Synuclein
- tau Proteins
- Polyglutamic Acid
|
Topics |
- Amyotrophic Lateral Sclerosis
(genetics, pathology)
- C9orf72 Protein
(genetics, metabolism)
- Cells, Cultured
- DNA Repeat Expansion
- DNA-Binding Proteins
(metabolism)
- Dipeptides
(genetics, metabolism)
- Frontotemporal Lobar Degeneration
(genetics, pathology)
- Humans
- Phosphorylation
- Polyglutamic Acid
(metabolism)
- Repetitive Sequences, Amino Acid
- alpha-Synuclein
(metabolism)
- tau Proteins
(metabolism)
|