Small Hexokinase 1 Peptide against Toxic SOD1 G93A Mitochondrial Accumulation in ALS Rescues the ATP-Related Respiration.

Andrea Magrì,Francesca Guarino,Pierpaolo Risiglione,Beatrice Formicola,Francesca Re,Stefania Zimbone,Marianna Flora Tomasello,Antonella Caccamo,Cristina Arrigoni,Angela Messina

doi:10.3390/biomedicines9080948

Abstract

Mutations in Cu/Zn Superoxide Dismutase (SOD1) gene represent one of the most common causes of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder that specifically affects motor neurons (MNs). The dismutase-active SOD1 G93A mutant is responsible for the formation of toxic aggregates onto the mitochondrial surface, using the Voltage-Dependent Anion Channel 1 (VDAC1) as an anchor point to the organelle. VDAC1 is the master regulator of cellular bioenergetics and by binding to hexokinases (HKs) it controls apoptosis. In ALS, however, SOD1 G93A impairs VDAC1 activity and displaces HK1 from mitochondria, promoting organelle dysfunction, and cell death. Using an ALS cell model, we demonstrate that a small synthetic peptide derived from the HK1 sequence (NHK1) recovers the cell viability in a dose–response manner and the defective mitochondrial respiration profile relative to the ADP phosphorylation. This correlates with an unexpected increase of VDAC1 expression and a reduction of SOD1 mutant accumulation at the mitochondrial level. Overall, our findings provide important new insights into the development of therapeutic molecules to fight ALS and help to better define the link between altered mitochondrial metabolism and MNs death in the disease.

Highlights

We demonstrate that NHK1 administration recovers the loss of cell viability induced by SOD1 G93A expression in a dose-dependent manner and significantly improves the whole respiratory profile of mitochondria, by increasing the ATP-linked oxygen flows
According to the GRAVY index [54], NHK1 shows physico-chemical features that supports its suitability as a cell-penetrating molecules
NHK1-fluoresceine isothiocyanate (FITC) was added to the apical compartment and the fluorescence in the basolateral compartment was monitored over time

Summary

Introduction

ALS is predominantly sporadic, scientific evidence suggests a genetic contribution in all cases, with a Mendelian pattern of inheritance observable in about 10% of 4.0/). Biomedicines 2021, 9, 948 patients [2]. Cu/Zn superoxide dismutase (SOD1) was the first gene linked to familial ALS (fALS) [3] and, to date, more than 180 mutations in the 153-codon sequence have been associated with a fifth of the overall inherited cases (ALS on-line database: www.alsod.ac.uk, 2020). In the majority of cases, ALS-linked mutations do not cause the loss of dismutase activity, as demonstrated from the extensive studies of SOD1 G93A mutant, but rather the adoption of misfolded conformations and/or a common aberrant hydrophobic behavior, triggering its accumulation [4,5,6,7]

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Results

Conclusion