Abstract
ObjectiveTo determine, when, how, and which neurons initiate the onset of pathophysiology in amyotrophic lateral sclerosis (ALS) using a transgenic mutant sod1 zebrafish model and identify neuroprotective drugs.MethodsProteinopathies such as ALS involve mutant proteins that misfold and activate the heat shock stress response (HSR). The HSR is indicative of neuronal stress, and we used a fluorescent hsp70-DsRed reporter in our transgenic zebrafish to track neuronal stress and to measure functional changes in neurons and muscle over the course of the disease.ResultsWe show that mutant sod1 fish first exhibited the HSR in glycinergic interneurons at 24 hours postfertilization (hpf). By 96 hpf, we observed a significant reduction in spontaneous glycinergic currents induced in spinal motor neurons. The loss of inhibition was followed by increased stress in the motor neurons of symptomatic adults and concurrent morphological changes at the neuromuscular junction (NMJ) indicative of denervation. Riluzole, the only approved ALS drug and apomorphine, an NRF2 activator, reduced the observed early neuronal stress response.InterpretationThe earliest event in the pathophysiology of ALS in the mutant sod1 zebrafish model involves neuronal stress in inhibitory interneurons, resulting from mutant Sod1 expression. This is followed by a reduction in inhibitory input to motor neurons. The loss of inhibitory input may contribute to the later development of neuronal stress in motor neurons and concurrent inability to maintain the NMJ. Riluzole, the approved drug for use in ALS, modulates neuronal stress in interneurons, indicating a novel mechanism of riluzole action. ANN NEUROL 2013;73:246–258
Highlights
The highest expresser WTos4-Sh4 line showed a minimal level of DsRed induction, despite having high transgene copy numbers and 3-fold increased Sod[1] protein expression; levels were identical to the G93Ros10-Sh1 mutant line
We have extended our analysis of mutant zebrafish to track early, presymptomatic perturbations associated with the Sod[1] mutation
We find that in early stages of development, inhibitory neurons are sensitive to the presence of mutant Sod[1], activating the stress response upon its expression
Summary
To determine, when, how, and which neurons initiate the onset of pathophysiology in amyotrophic lateral sclerosis (ALS) using a transgenic mutant sod[1] zebrafish model and identify neuroprotective drugs. The HSR is an endogenous cellular pathway that attempts to refold the damaged proteins in stressed cells, this response is not always sufficient or beneficial.[15] the HSR-mediated DsRed fluorescence in the sod[1] zebrafish model of ALS represents a useful tool for monitoring perturbations in cellular homeostasis caused by sod[1] mutation This facilitates the mapping of disease focality and spread through the central nervous system (CNS) by the spatiotemporal readout of the neuronal stress response in the spinal cord of mutant zebrafish and provides an understanding of the cells and networks involved in disease propagation in ALS. The sod[1] zebrafish model may by itself not be sufficient in developing new therapies for ALS, this model system would provide a rapid way to triage compounds for screening in higher vertebrate models, with the potential for more rapid identification of promising compounds for translation into human clinical trials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
