A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by progressive degeneration of motor neurons. Mislocalization of TAR DNA-binding protein 43 (TDP-43) is an early event in the formation of cytoplasmic TDP-43-positive inclusions in motor neurons and a hallmark of ALS. Howeve...

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Autores principales:	Yu-Ju Liu, Hung-Chih Kuo, Yijuang Chern
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	ALS AMPK nuclear transport translation S6 Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571
Acceso en línea:	https://doaj.org/article/52a7d3f8cf4a4ab29473f8dcf59123f4
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spelling	oai:doaj.org-article:52a7d3f8cf4a4ab29473f8dcf59123f42021-11-12T04:26:16ZA system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS1095-953X10.1016/j.nbd.2021.105531https://doaj.org/article/52a7d3f8cf4a4ab29473f8dcf59123f42021-12-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S0969996121002801https://doaj.org/toc/1095-953XAmyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by progressive degeneration of motor neurons. Mislocalization of TAR DNA-binding protein 43 (TDP-43) is an early event in the formation of cytoplasmic TDP-43-positive inclusions in motor neurons and a hallmark of ALS. However, the underlying mechanism and the pathogenic impact of this mislocalization are relatively unexplored. We previously reported that abnormal AMPK activation mediates TDP-43 mislocalization in motor neurons of humans and mice with ALS. In the present study, we hypothesized that other nuclear proteins are mislocalized in the cytoplasm of motor neurons due to the AMPK-mediated phosphorylation of importin-α1 and subsequently contribute to neuronal degeneration in ALS. To test this hypothesis, we analyzed motor neurons of sporadic ALS patients and found that when AMPK is activated, importin-α1 is abnormally located in the nucleus. Multiple integrative molecular and cellular approaches (including proteomics, immunoprecipitation/western blot analysis, immunohistological evaluations and gradient analysis of preribosomal complexes) were employed to demonstrate that numerous RNA binding proteins are mislocalized in a rodent motor neuron cell line (NSC34) and human motor neurons derived from iPSCs during AMPK activation. We used comparative proteomic analysis of importin-α1 complexes that were immunoprecipitated with a phosphorylation-deficient mutant of importin-α1 (importin-α1-S105A) and a phosphomimetic mutant of importin-α1 (importin-α1-S105D) to identify 194 proteins that have stronger affinity for the unphosphorylated form than the phosphorylated form of importin-α1. Furthermore, GO and STRING analyses suggested that RNA processing and protein translation is the major machinery affected by abnormalities in the AMPK-importin-α1 axis. Consistently, the expression of importin-α1-S105D alters the assembly of preribosomal complexes and increases cell apoptosis. Collectively, we propose that by impairing importin-α1-mediated nuclear import, abnormal AMPK activation in motor neurons alters the cellular distribution of many RNA-binding proteins, which pathogenically affect multiple cellular machineries in motor neurons and contribute to ALS pathogenesis.Yu-Ju LiuHung-Chih KuoYijuang ChernElsevierarticleALSAMPKnuclear transporttranslationS6Neurosciences. Biological psychiatry. NeuropsychiatryRC321-571ENNeurobiology of Disease, Vol 160, Iss , Pp 105531- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	ALS AMPK nuclear transport translation S6 Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571
spellingShingle	ALS AMPK nuclear transport translation S6 Neurosciences. Biological psychiatry. Neuropsychiatry RC321-571 Yu-Ju Liu Hung-Chih Kuo Yijuang Chern A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
description	Amyotrophic lateral sclerosis (ALS) is a motor neuron disease characterized by progressive degeneration of motor neurons. Mislocalization of TAR DNA-binding protein 43 (TDP-43) is an early event in the formation of cytoplasmic TDP-43-positive inclusions in motor neurons and a hallmark of ALS. However, the underlying mechanism and the pathogenic impact of this mislocalization are relatively unexplored. We previously reported that abnormal AMPK activation mediates TDP-43 mislocalization in motor neurons of humans and mice with ALS. In the present study, we hypothesized that other nuclear proteins are mislocalized in the cytoplasm of motor neurons due to the AMPK-mediated phosphorylation of importin-α1 and subsequently contribute to neuronal degeneration in ALS. To test this hypothesis, we analyzed motor neurons of sporadic ALS patients and found that when AMPK is activated, importin-α1 is abnormally located in the nucleus. Multiple integrative molecular and cellular approaches (including proteomics, immunoprecipitation/western blot analysis, immunohistological evaluations and gradient analysis of preribosomal complexes) were employed to demonstrate that numerous RNA binding proteins are mislocalized in a rodent motor neuron cell line (NSC34) and human motor neurons derived from iPSCs during AMPK activation. We used comparative proteomic analysis of importin-α1 complexes that were immunoprecipitated with a phosphorylation-deficient mutant of importin-α1 (importin-α1-S105A) and a phosphomimetic mutant of importin-α1 (importin-α1-S105D) to identify 194 proteins that have stronger affinity for the unphosphorylated form than the phosphorylated form of importin-α1. Furthermore, GO and STRING analyses suggested that RNA processing and protein translation is the major machinery affected by abnormalities in the AMPK-importin-α1 axis. Consistently, the expression of importin-α1-S105D alters the assembly of preribosomal complexes and increases cell apoptosis. Collectively, we propose that by impairing importin-α1-mediated nuclear import, abnormal AMPK activation in motor neurons alters the cellular distribution of many RNA-binding proteins, which pathogenically affect multiple cellular machineries in motor neurons and contribute to ALS pathogenesis.
format	article
author	Yu-Ju Liu Hung-Chih Kuo Yijuang Chern
author_facet	Yu-Ju Liu Hung-Chih Kuo Yijuang Chern
author_sort	Yu-Ju Liu
title	A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
title_short	A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
title_full	A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
title_fullStr	A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
title_full_unstemmed	A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS
title_sort	system-wide mislocalization of rna-binding proteins in motor neurons is a new feature of als
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/52a7d3f8cf4a4ab29473f8dcf59123f4
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A system-wide mislocalization of RNA-binding proteins in motor neurons is a new feature of ALS

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