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The human G93A-SOD1 mutation in a pre-symptomatic rat model of amyotrophic lateral sclerosis increases the vulnerability to a mild spinal cord compression.

Jokic N, Yip PK, Michael-Titus A, Priestley JV, Malaspina A - BMC Genomics (2010)

Bottom Line: Traumatic injuries can undermine neurological functions and act as risk factors for the development of irreversible and fatal neurodegenerative disorders like amyotrophic lateral sclerosis (ALS).The poor functional recovery observed in G93A-SOD1 transgenic animals was accompanied by the induction of fewer pro-survival signals, by an early activation of inflammatory markers, of several pro-apoptotic genes involved in cytochrome-C release and by the persistent up-regulation of the heavy neurofilament subunits and of genes involved in membrane excitability.In an experimental paradigm of mild mechanical trauma which causes no major tissue damage, the G93A-SOD1 gene mutation alters the balance between pro-apoptotic and pro-survival molecular signals in the spinal cord tissue from the pre-symptomatic rat, leading to a premature activation of molecular pathways implicated in the natural development of ALS.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Neuroscience and Trauma, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, UK.

ABSTRACT

Background: Traumatic injuries can undermine neurological functions and act as risk factors for the development of irreversible and fatal neurodegenerative disorders like amyotrophic lateral sclerosis (ALS). In this study, we have investigated how a mutation of the superoxide dismutase 1 (SOD1) gene, linked to the development of ALS, modifies the acute response to a gentle mechanical compression of the spinal cord. In a 7-day post-injury time period, we have performed a comparative ontological analysis of the gene expression profiles of injured spinal cords obtained from pre-symptomatic rats over-expressing the G93A-SOD1 gene mutation and from wild type (WT) littermates.

Results: The steady post-injury functional recovery observed in WT rats was accompanied by the early activation at the epicenter of injury of several growth-promoting signals and by the down-regulation of intermediate neurofilaments and of genes involved in the regulation of ion currents at the 7 day post-injury time point. The poor functional recovery observed in G93A-SOD1 transgenic animals was accompanied by the induction of fewer pro-survival signals, by an early activation of inflammatory markers, of several pro-apoptotic genes involved in cytochrome-C release and by the persistent up-regulation of the heavy neurofilament subunits and of genes involved in membrane excitability. These molecular changes occurred along with a pronounced atrophy of spinal cord motor neurones in the G93A-SOD1 rats compared to WT littermates after compression injury.

Conclusions: In an experimental paradigm of mild mechanical trauma which causes no major tissue damage, the G93A-SOD1 gene mutation alters the balance between pro-apoptotic and pro-survival molecular signals in the spinal cord tissue from the pre-symptomatic rat, leading to a premature activation of molecular pathways implicated in the natural development of ALS.

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Expression of neurofilament heavy chain and synaptophysin in ventral spinal cord at 24 hours after compression SCI. Neurofilament heavy chain (Nfh; clone N52) staining of spinal cord sections is clearly visible in motor neurons (arrows) and adjacent axons in both WT (A) and G93A-SOD1 (B) which is significantly stronger in the G93A-SOD1 (* P = 0.03; E). Scale bar = 100 μm. Transverse sections are taken within a segment 10 mm caudal to the injury epicenter. Synaptophysin (SYN) immunoreactive synaptic boutons (arrows) can be seen surrounding unstained motor neuron cell bodies in both WT (C) and G93A-SOD1 (D) spinal cord, with no difference in SYN distribution between the two genetic types. The intensity of staining is non-significantly different between the G93A-SOD1 and wild type spinal cords (F). Scale bar = 25 μm. SCI-SOD1: spinal cord tissue from rats over-expressing the G93A-SOD1 gene mutation. SCI-WT: spinal cord tissue from WT rats. Western blot of spinal cord rostral to the injury epicenter obtained from WT and G93A-SOD1 rats. Three spinal cord samples for both WT and G93A-SOD1 were used (G). A significant increase in Nfh (clone 52) expression levels can be detected in G93A-SOD1 rats compared to WT rats with β-actin as the internal control (* P = 0.041; H).
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Figure 8: Expression of neurofilament heavy chain and synaptophysin in ventral spinal cord at 24 hours after compression SCI. Neurofilament heavy chain (Nfh; clone N52) staining of spinal cord sections is clearly visible in motor neurons (arrows) and adjacent axons in both WT (A) and G93A-SOD1 (B) which is significantly stronger in the G93A-SOD1 (* P = 0.03; E). Scale bar = 100 μm. Transverse sections are taken within a segment 10 mm caudal to the injury epicenter. Synaptophysin (SYN) immunoreactive synaptic boutons (arrows) can be seen surrounding unstained motor neuron cell bodies in both WT (C) and G93A-SOD1 (D) spinal cord, with no difference in SYN distribution between the two genetic types. The intensity of staining is non-significantly different between the G93A-SOD1 and wild type spinal cords (F). Scale bar = 25 μm. SCI-SOD1: spinal cord tissue from rats over-expressing the G93A-SOD1 gene mutation. SCI-WT: spinal cord tissue from WT rats. Western blot of spinal cord rostral to the injury epicenter obtained from WT and G93A-SOD1 rats. Three spinal cord samples for both WT and G93A-SOD1 were used (G). A significant increase in Nfh (clone 52) expression levels can be detected in G93A-SOD1 rats compared to WT rats with β-actin as the internal control (* P = 0.041; H).

Mentions: To confirm that the spinal cord regulation of Nfh expression varies between WT and G93A-SOD1 animals at different time-points from injury (as shown using direct differential gene expression analysis by Bead-array and real-time RT-PCR, Figures 6, 7) we have carried out immunostaining for Nfh in comparable sections of spinal cord caudal to the epicenter of compression SCI, from WT and G93A-SOD1 rats (Figure 8A-B). Nfh expression by immunostaining appeared tendentially higher in the G93A-SOD1 spinal cord at all the post-injury time points considered when compared to the WT spinal cord, although only the 24 hour time point displayed a statistically significant difference (Figure 8E; p < 0.03). This significant difference in Nfh protein expression levels between the two groups at 24 h post-injury was further confirmed using Western blotting (Figure 8G-H).


The human G93A-SOD1 mutation in a pre-symptomatic rat model of amyotrophic lateral sclerosis increases the vulnerability to a mild spinal cord compression.

Jokic N, Yip PK, Michael-Titus A, Priestley JV, Malaspina A - BMC Genomics (2010)

Expression of neurofilament heavy chain and synaptophysin in ventral spinal cord at 24 hours after compression SCI. Neurofilament heavy chain (Nfh; clone N52) staining of spinal cord sections is clearly visible in motor neurons (arrows) and adjacent axons in both WT (A) and G93A-SOD1 (B) which is significantly stronger in the G93A-SOD1 (* P = 0.03; E). Scale bar = 100 μm. Transverse sections are taken within a segment 10 mm caudal to the injury epicenter. Synaptophysin (SYN) immunoreactive synaptic boutons (arrows) can be seen surrounding unstained motor neuron cell bodies in both WT (C) and G93A-SOD1 (D) spinal cord, with no difference in SYN distribution between the two genetic types. The intensity of staining is non-significantly different between the G93A-SOD1 and wild type spinal cords (F). Scale bar = 25 μm. SCI-SOD1: spinal cord tissue from rats over-expressing the G93A-SOD1 gene mutation. SCI-WT: spinal cord tissue from WT rats. Western blot of spinal cord rostral to the injury epicenter obtained from WT and G93A-SOD1 rats. Three spinal cord samples for both WT and G93A-SOD1 were used (G). A significant increase in Nfh (clone 52) expression levels can be detected in G93A-SOD1 rats compared to WT rats with β-actin as the internal control (* P = 0.041; H).
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Related In: Results  -  Collection

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Figure 8: Expression of neurofilament heavy chain and synaptophysin in ventral spinal cord at 24 hours after compression SCI. Neurofilament heavy chain (Nfh; clone N52) staining of spinal cord sections is clearly visible in motor neurons (arrows) and adjacent axons in both WT (A) and G93A-SOD1 (B) which is significantly stronger in the G93A-SOD1 (* P = 0.03; E). Scale bar = 100 μm. Transverse sections are taken within a segment 10 mm caudal to the injury epicenter. Synaptophysin (SYN) immunoreactive synaptic boutons (arrows) can be seen surrounding unstained motor neuron cell bodies in both WT (C) and G93A-SOD1 (D) spinal cord, with no difference in SYN distribution between the two genetic types. The intensity of staining is non-significantly different between the G93A-SOD1 and wild type spinal cords (F). Scale bar = 25 μm. SCI-SOD1: spinal cord tissue from rats over-expressing the G93A-SOD1 gene mutation. SCI-WT: spinal cord tissue from WT rats. Western blot of spinal cord rostral to the injury epicenter obtained from WT and G93A-SOD1 rats. Three spinal cord samples for both WT and G93A-SOD1 were used (G). A significant increase in Nfh (clone 52) expression levels can be detected in G93A-SOD1 rats compared to WT rats with β-actin as the internal control (* P = 0.041; H).
Mentions: To confirm that the spinal cord regulation of Nfh expression varies between WT and G93A-SOD1 animals at different time-points from injury (as shown using direct differential gene expression analysis by Bead-array and real-time RT-PCR, Figures 6, 7) we have carried out immunostaining for Nfh in comparable sections of spinal cord caudal to the epicenter of compression SCI, from WT and G93A-SOD1 rats (Figure 8A-B). Nfh expression by immunostaining appeared tendentially higher in the G93A-SOD1 spinal cord at all the post-injury time points considered when compared to the WT spinal cord, although only the 24 hour time point displayed a statistically significant difference (Figure 8E; p < 0.03). This significant difference in Nfh protein expression levels between the two groups at 24 h post-injury was further confirmed using Western blotting (Figure 8G-H).

Bottom Line: Traumatic injuries can undermine neurological functions and act as risk factors for the development of irreversible and fatal neurodegenerative disorders like amyotrophic lateral sclerosis (ALS).The poor functional recovery observed in G93A-SOD1 transgenic animals was accompanied by the induction of fewer pro-survival signals, by an early activation of inflammatory markers, of several pro-apoptotic genes involved in cytochrome-C release and by the persistent up-regulation of the heavy neurofilament subunits and of genes involved in membrane excitability.In an experimental paradigm of mild mechanical trauma which causes no major tissue damage, the G93A-SOD1 gene mutation alters the balance between pro-apoptotic and pro-survival molecular signals in the spinal cord tissue from the pre-symptomatic rat, leading to a premature activation of molecular pathways implicated in the natural development of ALS.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Neuroscience and Trauma, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, UK.

ABSTRACT

Background: Traumatic injuries can undermine neurological functions and act as risk factors for the development of irreversible and fatal neurodegenerative disorders like amyotrophic lateral sclerosis (ALS). In this study, we have investigated how a mutation of the superoxide dismutase 1 (SOD1) gene, linked to the development of ALS, modifies the acute response to a gentle mechanical compression of the spinal cord. In a 7-day post-injury time period, we have performed a comparative ontological analysis of the gene expression profiles of injured spinal cords obtained from pre-symptomatic rats over-expressing the G93A-SOD1 gene mutation and from wild type (WT) littermates.

Results: The steady post-injury functional recovery observed in WT rats was accompanied by the early activation at the epicenter of injury of several growth-promoting signals and by the down-regulation of intermediate neurofilaments and of genes involved in the regulation of ion currents at the 7 day post-injury time point. The poor functional recovery observed in G93A-SOD1 transgenic animals was accompanied by the induction of fewer pro-survival signals, by an early activation of inflammatory markers, of several pro-apoptotic genes involved in cytochrome-C release and by the persistent up-regulation of the heavy neurofilament subunits and of genes involved in membrane excitability. These molecular changes occurred along with a pronounced atrophy of spinal cord motor neurones in the G93A-SOD1 rats compared to WT littermates after compression injury.

Conclusions: In an experimental paradigm of mild mechanical trauma which causes no major tissue damage, the G93A-SOD1 gene mutation alters the balance between pro-apoptotic and pro-survival molecular signals in the spinal cord tissue from the pre-symptomatic rat, leading to a premature activation of molecular pathways implicated in the natural development of ALS.

Show MeSH
Related in: MedlinePlus