Mitigating Motor Neuronal Loss in C. elegans Model of ALS8

Wendy Zhang,Johnny K Ngsee,Antonio Colavita

doi:10.1038/s41598-017-11798-6

Wendy Zhang, Johnny K Ngsee + Show 1 more

Open Access

https://doi.org/10.1038/s41598-017-11798-6

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Journal: Scientific Reports	Publication Date: Sep 14, 2017
Citations: 8	License type: open-access

Affiliation: Ottawa Hospital, University of Ottawa

Abstract

ALS8 is a late-onset familial autosomal dominant form of Amyotrophic Lateral Sclerosis (ALS) caused by a point mutation (P56S) in the VAPB gene (VAMP associated protein isoform B). Here, we generated two C. elegans models of the disease: a transgenic model where human VAPB wild-type (WT) or P56S mutant was expressed in a subset of motor neurons, and a second model that targeted inducible knockdown of the worm’s orthologue, vpr-1. Overexpression of human VAPB in DA neurons caused a backward locomotion defect, axonal misguidance, and premature neuronal death. Knockdown of vpr-1 recapitulated the reduction in VAPB expression associated with sporadic cases of human ALS. It also caused backward locomotion defects as well as an uncoordinated phenotype, and age-dependent, progressive motor neuronal death. Furthermore, inhibiting phosphatidylinositol-4 (PtdIns 4)-kinase activity with PIK-93 reduced the incidence of DA motor neuron loss and improved backward locomotion. This supports the loss of VAPB function in ALS8 pathogenesis and suggests that reducing intracellular PtdIns4P might be an effective therapeutic strategy in delaying progressive loss of motor neurons.

Highlights

Amyotrophic Lateral Sclerosis (ALS) is a late-onset, progressive neurodegenerative disease that results in rapid loss of upper and lower motor neurons
All strains were morphologically normal, both adult Day 3 VAPB-WT and VAPB-P56S worms exhibited fewer body bends over a longer duration of time (0.42 ± 0.02 turns/second and 0.47 ± 0.03 turns/second, respectively), which resulted in a significant decrease in the rate of backward locomotion compared to the control (0.71 ± 0.03 turns/second, p < 0.001) (Fig. 1)
The rate of backward locomotion decreased with age in all worms at adult Day 11, but the decline was more pronounced in worms overexpressing VAPB-WT or VAPB-P56S, and both were significantly lower than control

Summary

Introduction

Amyotrophic Lateral Sclerosis (ALS) is a late-onset, progressive neurodegenerative disease that results in rapid loss of upper and lower motor neurons. A point mutation in the vesicle-associated membrane protein (VAMP)/ synaptobrevin-associated membrane protein B gene (VAPB) causes late-onset familial ALS81. This mutation was first identified in a large Brazilian family, but the same mutation is found in European[2] and Asian[3] populations. To characterize the role of VAPB in motor neurons, we generated two C. elegans models: one expressing human VAPB-WT or P56S, and another with the knockdown of C. elegans vpr-1. Overexpression of human VAPB in DA neurons caused backward locomotion defects and premature neuronal death. Knockdown of vpr-1 in C. elegans caused backward locomotion defects as well as age-dependent motor neuronal death. Incidence of DA neuronal loss and partially rescued backward-directed locomotor defects, suggesting restoration of phosphatidylinositol-4-phosphate (PtdIns4P) homeostasis may bypass VPR-1 function

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Conclusion