ABSTRACT
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.
ABSTRACT
The SOD1-G93A transgenic mouse is the most widely used animal model of amyotrophic lateral sclerosis (ALS). At ALS TDI we developed a phenotypic screening protocol, demonstrated in video herein, which reliably assesses the neuromuscular function of SOD1-G93A mice in a quick manner. This protocol encompasses a simple neurological scoring system (NeuroScore) designed to assess hindlimb function. NeuroScore is focused on hindlimb function because hindlimb deficits are the earliest reported neurological sign of disease in SOD1-G93A mice. The protocol developed by ALS TDI provides an unbiased assessment of onset of paresis (slight or partial paralysis), progression and severity of paralysis and it is sensitive enough to identify drug-induced changes in disease progression. In this report, the combination of a detailed manuscript with video minimizes scoring ambiguities and inter-experimenter variability thus allowing for the protocol to be adopted by other laboratories and enabling comparisons between studies taking place at different settings. We believe that this video protocol can serve as an excellent training tool for present and future ALS researchers.
Subject(s)
Amyotrophic Lateral Sclerosis/diagnosis , Amyotrophic Lateral Sclerosis/enzymology , Disease Models, Animal , Superoxide Dismutase/genetics , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/pathology , Animals , Disease Progression , Female , Hindlimb/physiopathology , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Superoxide Dismutase/metabolismABSTRACT
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by loss of motor neurons. The mechanisms leading to motor neuron degeneration in ALS are unclear. However, there is evidence for involvement of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in ALS, notably in mutant SOD1 mediated models of ALS. Stress induced phosphorylation of the eIF2 alpha subunit by eukaryotic translation initiation factor 2-alpha kinase 3 Perk activates the UPR. Guanabenz is a centrally acting alpha2 adrenergic receptor agonist shown to interact with a regulatory subunit of the protein phosphatase, Pp1/Gadd34, and selectively disrupt the dephosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eif2alpha). Here we demonstrate that guanabenz is protective in fibroblasts expressing G93A mutant SOD1 when they are exposed to tunicamycin mediated ER stress. However, in contrast to other reports, guanabenz treatment accelerated ALS-like disease progression in a strain of mutant SOD1 transgenic ALS mice. This study highlights challenges of pharmacological interventions of cellular stress responses in whole animal models of ALS.
Subject(s)
Adrenergic alpha-2 Receptor Agonists/pharmacology , Amyotrophic Lateral Sclerosis/pathology , Endoplasmic Reticulum Stress/drug effects , Guanabenz/pharmacology , Superoxide Dismutase/drug effects , Amyotrophic Lateral Sclerosis/genetics , Animals , Antihypertensive Agents/pharmacology , Disease Models, Animal , Disease Progression , Eukaryotic Initiation Factor-2/metabolism , Fibroblasts/drug effects , Mice , Mice, Inbred C57BL , Mice, Transgenic , Nerve Degeneration/pathology , Phosphorylation , Protein Phosphatase 1/metabolism , Superoxide Dismutase/genetics , Tunicamycin , Unfolded Protein Response , eIF-2 Kinase/metabolismABSTRACT
ALS therapy development has been hindered by the lack of rodent animal models. The discovery of TDP-43, a transcription factor that accumulates in the cytoplasm of motor neurons (MNs) in most cases of ALS, prompted attempts to develop TDP-43-based models of the disease. The current study sought to examine, in extensive detail, the emerging disease phenotype of a transgenic mouse model that overexpresses a mutant human TDP-43 (hTDP-43) gene under mouse prion promoter control. Careful attention was given to ALS-like characteristics to determine the appropriateness of this model for testing therapies for ALS. In light of previous reports that gastrointestinal (GI) dysfunction is responsible for early death in these mice, gut immunohistochemistry (IHC) and longitudinal gut motility assays were used to identify the onset and the progression of these defects. IHC studies revealed that site-specific overexpression of the hTDP-43 transgene in colonic myenteric plexes resulted in progressive neurodegeneration in this region. This change was associated with progressively reduced GI motility, culminating in frank stasis that was primarily responsible for decreasing longevity in these mice. The disease phenotype was gender- and genetic background-dependent, with congenic C57BL/6J male mice exhibiting the most aggressive form of the disease. Spinal cord IHC revealed ubiquitin-positive inclusions, but not TDP-43 aggregates, in the cytoplasm of MNs. Neither gender exhibited compelling ALS-like neuromuscular deficits, irrespective of age. While this model may be useful for studying GI tract neurodegeneration, in its present state it does not display a phenotype suitable for testing ALS therapeutics.
