Storage of Mutant Human SOD1 in Non-Neural Cells from the Type-1 Amyotrophic Lateral Sclerosis ratG93A Model Correlated with the Lysosomes’ Dysfunction

Abstract

Herein, we explored the impact of the lysosome dysfunction during the progression of Amyotrophic Lateral Sclerosis type-1 (ALS1). We conducted the study in non-neural cells, primary fibroblasts (rFFFs), and bone marrow-mesenchymal stem cells (rBM-MSCs), isolated from the animal model ratG93A for ALS1 at two stages of the disease: Pre-symptomatic-stage (ALS1-PreS) and Terminal-stage (ALS1-EndS). We documented the storage of human mutant Superoxide Dismutase 1, SOD1G93A (SOD1*) in the lysosomes of ALS1-rFFFs and ALS1-rBM-MSCs and demonstrated the hallmarks of the disease in non-neural cells as in ratG93A-ALS1-tissues. We showed that the SOD1* storage is associated with the altered glycohydrolases and proteases levels in tissues and both cell types from ALS1-PreS to ALS1-EndS. Only in ALS1-rFFFs, the lysosomes lost homeostasis, enlarge drastically, and contribute to the cell metabolic damage. Contrariwise, in ALS1-rBM-MSCs, we found a negligible metabolic dysfunction, which makes these cells’ status similar to WT. We addressed this phenomenon to a safety mechanism perhaps associated with an enhanced lysosomal autophagic activity in ALS1-rBM-MSCs compared to ALS1-rFFFs, in which the lysosomal level of LC3-II/LC3I was comparable to that of WT-rFFFs. We suggested that the autophagic machinery could balance the storage of SOD1* aggregates and the lysosomal enzyme dysfunction even in ALS1-EndS-stem cells.

Tight Regulation of Mechanotransducer Proteins Distinguishes the Response of Adult Multipotent Mesenchymal Cells on PBCE-Derivative Polymer Films with Different Hydrophilicity and Stiffness

“…Immunofluorescence was carried out as previously described [ 17 , 25 , 28 , 49 ]. In brief, cells seeded on PBCE and BDG50 squares, as well as on the glass coverslip (GC), as a negative control, were washed twice with PBS, fixed for 20 min in 4% paraformaldehyde, washed twice with PBS, and then permeabilized (PBS + 3% FBS, 0.5% Triton X-100) and blocked (PBS + 3% FBS, 0.05% Triton X-100) for 1 h at room temperature.…”

Characterization of the p.L145F and p.S135N Mutations in SOD1: Impact on the Metabolism of Fibroblasts Derived from Amyotrophic Lateral Sclerosis Patients

“…Remarkably, ALS fibroblasts showed an increased proliferation rate. This increased proliferation rate, together with the activation of the ERK pathway, has recently been reported in fibroblasts and motor neurons bearing other mutations in SOD1 [52,66] and TDP43 [60]. However, it has not yet been established whether increased proliferation is triggered by a specific ALS-mutated protein, or whether it is a common trait to all disease-related mutations.…”

“…Skin cells can be collected at different stages of the disease. This enables the assessment of the progression of the cellular impairments, along with the clinical course, as has been shown in animal models [66]. Consequently, fibroblasts represent an adequate study model to screen for and detect ALS-induced changes, and can then be further characterized in iPSC-derived neural cells.…”

“…In fact, SOD1 might act as a transcription factor in response to an increase in ROS levels, and induce the expression of oxidative resistance and repair genes [11]. In light of this, similarly to the fibroblasts of the SOD G93A rat model [66], the accumulation of SOD1 in the perinuclear region might be explained by the inability of the mutated SOD1 to enter it. The role of SOD1 as transcription factor is currently being investigated; indeed, it might play a role in counteracting the effect of ROS at the cellular level.…”

Emerging Potential of the Phosphodiesterase (PDE) Inhibitor Ibudilast for Neurodegenerative Diseases: An Update on Preclinical and Clinical Evidence

“…TAR DNA binding protein (TDP-43) and mutant superoxide dismutase 1 (SOD1) are key proteins that form aggregates in ALS [ 73 , 74 ]. The dysregulation of the ubiquitin–proteasome and autophagosome–lysosome systems may result in impaired TDP-43 and SOD1 degradation, leading to the formation of TDP-43 and SOD1 aggregates [ 75 , 76 ].…”