Early gene expression changes in spinal cord from SOD1G93A Amyotrophic Lateral Sclerosis animal model

Abstract

Amyotrophic Lateral Sclerosis (ALS) is an adult-onset and fast progression neurodegenerative disease that leads to the loss of motor neurons. Mechanisms of selective motor neuron loss in ALS are unknown. The early events occurring in the spinal cord that may contribute to motor neuron death are not described, neither astrocytes participation in the pre-symptomatic phases of the disease. In order to identify ALS early events, we performed a microarray analysis employing a whole mouse genome platform to evaluate the gene expression pattern of lumbar spinal cords of transgenic SOD1G93A mice and their littermate controls at pre-symptomatic ages of 40 and 80 days. Differentially expressed genes were identified by means of the Bioconductor packages Agi4×44Preprocess and limma. FunNet web based tool was used for analysis of over-represented pathways. Furthermore, immunolabeled astrocytes from 40 and 80 days old mice were submitted to laser microdissection and RNA was extracted for evaluation of a selected gene by qPCR. Statistical analysis has pointed to 492 differentially expressed genes (155 up and 337 down regulated) in 40 days and 1105 (433 up and 672 down) in 80 days old ALS mice. KEGG analysis demonstrated the over-represented pathways tight junction, antigen processing and presentation, oxidative phosphorylation, endocytosis, chemokine signaling pathway, ubiquitin mediated proteolysis and glutamatergic synapse at both pre-symptomatic ages. Ube2i gene expression was evaluated in astrocytes from both transgenic ages, being up regulated in 40 and 80 days astrocytes enriched samples. Our data points to important early molecular events occurring in pre-symptomatic phases of ALS in mouse model. Early SUMOylation process linked to astrocytes might account to non-autonomous cell toxicity in ALS. Further studies on the signaling pathways presented here may provide new insights to better understand the events triggering motor neuron death in this devastating disorder.

Correlating serum micrornas and clinical parameters in amyotrophic lateral sclerosis

“…Some of the genes in this pathway that are upregulated in these disease models include tumor necrosis factor (TNF), endothelin1 (END1), and angiotensin (AGT). 44,45 In a recent study comparing 12 different commercially available miRNA expression platforms for studying differential expression in serum, the LNAbased quantitative PCR platform from Exiqon showed good reproducibility, accuracy, and the highest specificity. 46 Therefore, we believe this is a robust system to measure the expression of miR-NAs.…”

Deregulated expression of cytoskeleton related genes in the spinal cord and sciatic nerve of presymptomatic SOD1G93A Amyotrophic Lateral Sclerosis mouse model

“…The labeling procedure was performed according to adaptation of a previous description (De Oliveira et al, 2009, 2013). Taw-mounted mouse sciatic nerve sections (5 μm) were rapidly defrosted for 30 s and fixed with ice-cold acetone, for 3 min.…”

“…cDNA samples of microdissected cells and of cultured Schwann cells were synthesized from 1 μg of amplified RNA as described previously (De Oliveira et al, 2013). The cDNA of flow cytometry sorting Schwann cells was synthesized from 100 ng of total RNA.…”

ALS-linked SOD1 Mutants Enhance Outgrowth, Branching, and the Formation of Actin-Based Structures in Adult Motor Neurons

“…The second way that mutant SOD1 expression could enhance outgrowth and branching would be through upregulation of proregenerative signaling and cytoskeletal pathways. There are several published studies characterizing genetic changes in motor neurons from G93A mice at various stages of disease progression (D'Arrigo et al, 2010;de Oliveira et al, 2013;Ferraiuolo et al, 2007;Guipponi et al, 2010;Offen et al, 2009;Perrin et al, 2005;Saris et al, 2013;Yu et al, 2013). However, these studies have not reached consensus regarding the underlying genetics promoting ALS resistance, probably due to the variation in experimental design and tissue sampling.…”

“…Most of our current knowledge about surviving spinal motor neurons in ALS mouse models has largely been generated by gene expression profiling tissue and cells (Bandyopadhyay et al, 2013;Brockington et al, 2013;de Oliveira et al, 2013;Ferraiuolo et al, 2007;Lobsiger et al, 2007;Saxena et al, 2009). However, these studies provide just a single snapshot of the motor neuron's biology and only allow for inferences to be made about how changes in gene expression alter motor neuron physiology, allow them to resist degeneration, or compensate for dying neurons by forming new motor endplate attachments.…”