This video protocol describes a sensitive, reliable, and quick method for evaluating the neuromuscular deficits in a transgenic mouse...

A copper chelator known as diacetylbis(N(4)-methylthiosemicarbazonato) copper II (CuATSM), has been reported to be efficacious in multiple transgenic SOD1 models of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder affecting motor neurons. Here we report that we also observed CuATSM efficacy on disease onset and progression in a standardized litter-matched and gender-balanced efficacy study using B6SJL-SOD1G93A/1Gur mice. We also report improved survival trends with CuATSM treatment. In addition, we report a lack of efficacy by unmetallated ATSM in the same model using the same standardized study design. These results add to existing evidence supporting an efficacious role for copper delivery using chaperone molecules in mouse models of ALS.

Amyotrophic lateral sclerosis (ALS) has been linked to overactivity of the protein kinase RNA-like ER kinase (PERK) branch of the unfolded protein response (UPR) pathway, both in ALS patients and mouse models. However, attempts to pharmacologically modulate PERK for therapeutic benefit have yielded inconsistent and often conflicting results. This study sought to address these discrepancies by comprehensively evaluating three commonly used, CNS-penetrant, PERK modulators (GSK2606414, salubrinal, and Sephin1) in the same experimental models, with the goal of assessing the viability of targeting the PERK pathway as a therapeutic strategy for ALS. To achieve this goal, a tunicamycin-challenge assay was developed using wild-type mice to monitor changes in liver UPR gene expression in response to PERK pathway modulation. Subsequently, multiple dosing regimens of each PERK modulator were tested in standardized, well-powered, gender-matched, and litter-matched survival efficacy studies using the SOD1G93A mouse model of ALS. The alpha-2-adrenergic receptor agonist clonidine was also tested to elucidate the results obtained from the Sephin1, and of the previously reported guanabenz studies, by comparing the effects of presence or absence of α-2 agonism. The results revealed that targeting PERK may not be an ideal approach for ALS treatment. Inhibiting PERK with GSK2606414 or activating it with salubrinal did not confer therapeutic benefits. While Sephin1 showed some promising therapeutic effects, it appears that these outcomes were mediated through PERK-independent mechanisms. Clonidine also produced some favorable therapeutic effects, which were unexpected and not linked to the UPR. In conclusion, this study highlights the challenges of pharmacologically targeting PERK for therapeutic purposes in the SOD1G93A mouse model and suggests that exploring other targets within, and outside, the UPR may be more promising avenues for ALS treatment.

The hPFN1^G118V mouse model, overexpressing mutant human profilin1 linked to a rare form of ALS, was comprehensively characterized to assess its suitability for preclinical drug testing. Using a large cohort of nearly 250 transgenic and wild-type mice in a longitudinal study, we combined behavioral, electrophysiological, and neuropathological assessments to define the chronology of pathological events and assess inherent subject variability. The early stage of the disease in this model was characterized by elevated plasma neurofilament light chain levels, an effect that persisted and progressed throughout the course of the disease, followed by spinal cord neuroinflammation, suggesting that axonal pathology is the initiating event. The middle stage of the disease involved progressive neuromuscular decline, including reductions in compound muscle action potential (CMAP) and grip strength, accompanied by neuromuscular junction degeneration. The end-stage of the disease was characterized by the onset of visible changes such as weight loss, gait abnormalities and hindlimb paresis that quickly progressed to paralysis. At end-stage we also observed spinal motor neuron loss and TDP-43 pathology. The average humane endpoint was 213 days for females and 237 days for males. Our findings demonstrate that hPFN1^G118V mice recapitulate key ALS features with moderate disease progression and a reproducible disease course, making them a valuable model for therapeutic testing. Recommendations are provided to optimize study design for preclinical testing, emphasizing survival duration as the primary endpoint, with CMAP and plasma NFL as key secondary readouts.