Protein disulphide isomerase (PDI) is protective against amyotrophic lateral sclerosis (ALS)-related mutant Fused in Sarcoma (FUS) in in vitro models

S Parakh,J Sultana,S Shadfar,J D Atkin,D M Spencer,M Vidal,A Konopka,P Mehta,C J Thomas,E R Perri

doi:10.1038/s41598-021-96181-2

S Parakh, J Sultana + Show 8 more

Open Access

https://doi.org/10.1038/s41598-021-96181-2

Copy DOI

Journal: Scientific Reports	Publication Date: Sep 2, 2021
Citations: 6	License type: open-access

Affiliation: La Trobe University, Macquarie University

Abstract

Mutations in Fused in Sarcoma (FUS) are present in familial and sporadic cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). FUS is localised in the nucleus where it has important functions in DNA repair. However, in ALS/FTD, mutant FUS mislocalises from the nucleus to the cytoplasm where it forms inclusions, a key pathological hallmark of neurodegeneration. Mutant FUS also inhibits protein import into the nucleus, resulting in defects in nucleocytoplasmic transport. Fragmentation of the neuronal Golgi apparatus, induction of endoplasmic reticulum (ER) stress, and inhibition of ER-Golgi trafficking are also associated with mutant FUS misfolding in ALS. Protein disulphide isomerase (PDI) is an ER chaperone previously shown to be protective against misfolding associated with mutant superoxide dismutase 1 (SOD1) and TAR DNA-binding protein-43 (TDP-43) in cellular and zebrafish models. However, a protective role against mutant FUS in ALS has not been previously described. In this study, we demonstrate that PDI is protective against mutant FUS. In neuronal cell line and primary cultures, PDI restores defects in nuclear import, prevents the formation of mutant FUS inclusions, inhibits Golgi fragmentation, ER stress, ER-Golgi transport defects, and apoptosis. These findings imply that PDI is a new therapeutic target in FUS-associated ALS.

Highlights

Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset neurodegenerative disease, and pathological forms of transactive response DNA-binding protein-43 (TDP-43) are the hallmark of almost all amyotrophic lateral sclerosis (ALS) patients (97%)
Wild-type (WT) Fused in Sarcoma (FUS) or mutant R521G tagged with green fluorescent protein (GFP)[29], or vector pEGFP-N1 only as a control, were co-expressed with Protein disulphide isomerase (PDI) tagged with V 524 or empty vector, in a neuroblastoma cell line, Neuro-2a
Co-expression of PDI with mutant FUS resulted in significantly fewer inclusions compared to cells transfected with mutant FUS and empty vector (23%, *p < 0.05, Fig. 1D), and this proportion was similar to FUS-GFP-WT expressing cells

Summary

Introduction

Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset neurodegenerative disease, and pathological forms of transactive response DNA-binding protein-43 (TDP-43) are the hallmark of almost all ALS patients (97%). FUS−/− mice display abnormal neuronal morphology and are not viable due to disruption of immune cell development and genomic instability[2,12] Together these reports highlight the importance of FUS in normal cellular function, ALS and neurodegeneration more broadly. FUS is normally present in the nucleus, but in ALS/FTD it misfolds in the cytoplasm and forms inclusions in both neurons and g lia[5,6]. Fragmentation of the neuronal Golgi is widely described in ALS and is triggered following expression of mutant FUS22

Methods

Results

Conclusion