Characterization and molecular investigation of pathogenesis in a novel model of human familial ALS.
Lead Research Organisation:
University College London
Department Name: Institute of Neurology
Abstract
Amyotrophic lateral sclerosis, (ALS, also called Motor neurone disease) causes progressive paralysis due to the degeneration of motor nerve cells in the brain and spinal cord. People lose the ability to move their limbs, eat or speak and die from breathlessness, usually within 3 years of symptom onset. There is no effective treatment for the disease.
ALS can occur in one individual or within families when a defective gene is passed down through the generations. No clinical characteristic differentiates the familial forms from the others. SOD1 is the most frequently involved gene and the study of SOD1 defects is an opportunity for understanding ALS disease mechanisms and to identify therapeutic targets.
The purpose of this research project is to study a new mouse model which carries the exact same genetic defect as a group of ALS patients.
We will characterize the disease progression in the mice and so we will use the mice to analyze the disease mechanisms in the motor nerve cells in the very early stages of disease. The discovery of underlying disease mechanisms is fundamental to the identifying drug targets for clinical trials, and the mice may also be used as a disease model to test new therapies.
ALS can occur in one individual or within families when a defective gene is passed down through the generations. No clinical characteristic differentiates the familial forms from the others. SOD1 is the most frequently involved gene and the study of SOD1 defects is an opportunity for understanding ALS disease mechanisms and to identify therapeutic targets.
The purpose of this research project is to study a new mouse model which carries the exact same genetic defect as a group of ALS patients.
We will characterize the disease progression in the mice and so we will use the mice to analyze the disease mechanisms in the motor nerve cells in the very early stages of disease. The discovery of underlying disease mechanisms is fundamental to the identifying drug targets for clinical trials, and the mice may also be used as a disease model to test new therapies.
Technical Summary
Background
ALS is a relentlessly progressive disease, characterized by the degeneration of motor neurons in brain and spinal cord. 10% of cases are familial (fALS) and SOD1 is the most frequent causative gene. fALS and sporadic ALS (sALS) are clinically indistinguishable and misfolded SOD1 is found in sALS patients‘ spinal cords, making the study of SOD1-fALS relevant also to the sporadic disease. The discovery of fALS-causing mutations in TARDBP and FUS genes, both encoding RNA processing proteins, has highlighted the role of RNA in ALS pathogenesis and, intriguingly, mutant SOD1 (mtSOD1) has been shown to influence mRNA stability.
Numerous ALS transgenic mouse models are available and all overexpress mtSOD1, generating a biological context very different from that of patients, thus affecting studies of pathobiology, early-stage disease and therapeutics. No mouse models expressing endogenous levels of mutated protein have been generated on the assumption that over-expression is necessary to generate a motor phenotype.
The Fisher laboratory has mice carrying and endogenously expressing a single point mutation causative for human fALS (SOD1-D83G). We have preliminary data showing these mice develop a motor phenotype by 9 months of age, therefore providing a powerful tool for analyzing early-stage disease and the role of mutant SOD1 in RNA stability and pathophysiology.
Aims and Objectives
This project aims to define and characterize the progression of disease in this mouse line, compare with human pathology and then investigate early-stage motorneuron molecular changes.
Design and Methodology
1.Define disease time-course by longitudinal analysis.
- Motor phenotype will be analysed in statistically valid cohorts by monthly assessments including SHIRPA, rotarod, gripstrength.
- Muscle physiology and histopathology of brain, spinal cord, nerve, muscle will be assessed at 4 time-points.
- Spinal cord and brain pathology will be compared with post-mortem material from fALS-SOD1-D83G cases.
2.Study subtle preclinical-ALS changes.
We will analyze the motorneuron transcriptome by RNA-Seq analysis at the pre-clinical and early stage of disease. Results will be validated by real-time Q-PCR. These data will allow us to:
1) identify new pathogenetic molecular players and pathways;
2) verify pathways currently hypothesized to be involved in ALS;
3) investigate mRNAs known to be regulated by SOD1.
Scientific and Medical Opportunities
The development of valid disease models is a crucial step for both our understanding of ALS pathogenesis and the development of therapy.
SOD1-D83G mice avoid overexpression related artefacts and develop a slowly progressive disease, therefore offering the invaluable opportunity to study the subtle changes of the preclinical stage. Further, the availability of human post-mortem cases carrying the same mutation will allow us to compare human and mouse pathology. Studies of this type are extremely important and very rare in the current medical literature.
ALS is a relentlessly progressive disease, characterized by the degeneration of motor neurons in brain and spinal cord. 10% of cases are familial (fALS) and SOD1 is the most frequent causative gene. fALS and sporadic ALS (sALS) are clinically indistinguishable and misfolded SOD1 is found in sALS patients‘ spinal cords, making the study of SOD1-fALS relevant also to the sporadic disease. The discovery of fALS-causing mutations in TARDBP and FUS genes, both encoding RNA processing proteins, has highlighted the role of RNA in ALS pathogenesis and, intriguingly, mutant SOD1 (mtSOD1) has been shown to influence mRNA stability.
Numerous ALS transgenic mouse models are available and all overexpress mtSOD1, generating a biological context very different from that of patients, thus affecting studies of pathobiology, early-stage disease and therapeutics. No mouse models expressing endogenous levels of mutated protein have been generated on the assumption that over-expression is necessary to generate a motor phenotype.
The Fisher laboratory has mice carrying and endogenously expressing a single point mutation causative for human fALS (SOD1-D83G). We have preliminary data showing these mice develop a motor phenotype by 9 months of age, therefore providing a powerful tool for analyzing early-stage disease and the role of mutant SOD1 in RNA stability and pathophysiology.
Aims and Objectives
This project aims to define and characterize the progression of disease in this mouse line, compare with human pathology and then investigate early-stage motorneuron molecular changes.
Design and Methodology
1.Define disease time-course by longitudinal analysis.
- Motor phenotype will be analysed in statistically valid cohorts by monthly assessments including SHIRPA, rotarod, gripstrength.
- Muscle physiology and histopathology of brain, spinal cord, nerve, muscle will be assessed at 4 time-points.
- Spinal cord and brain pathology will be compared with post-mortem material from fALS-SOD1-D83G cases.
2.Study subtle preclinical-ALS changes.
We will analyze the motorneuron transcriptome by RNA-Seq analysis at the pre-clinical and early stage of disease. Results will be validated by real-time Q-PCR. These data will allow us to:
1) identify new pathogenetic molecular players and pathways;
2) verify pathways currently hypothesized to be involved in ALS;
3) investigate mRNAs known to be regulated by SOD1.
Scientific and Medical Opportunities
The development of valid disease models is a crucial step for both our understanding of ALS pathogenesis and the development of therapy.
SOD1-D83G mice avoid overexpression related artefacts and develop a slowly progressive disease, therefore offering the invaluable opportunity to study the subtle changes of the preclinical stage. Further, the availability of human post-mortem cases carrying the same mutation will allow us to compare human and mouse pathology. Studies of this type are extremely important and very rare in the current medical literature.