TDP-43 Knock-in Mouse Model for ALS Pathogenesis
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Solution Overview
Problem
Current ALS-TDP animal models face challenges in accurately assessing the pathological effects of ALS-associated TDP-43 mutations due to overexpression approaches, which complicate the differentiation between mutant and wild-type TDP-43 effects, leading to inadequate control over expression levels and confounding pathologies.
Innovation Solution
A genetically modified mouse model with a heterozygous mutation in the Tardbp gene, specifically the N390D mutation, is developed, exhibiting ALS-like phenotypes and motor neuron degeneration, allowing for controlled expression levels and precise study of TDP-43 pathogenesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overexpression approaches are used to study ALS-TDP disease mechanisms, then transgenic mouse models can exhibit MND-like phenotype and TDP-43 proteinopathies, but it becomes difficult to assess the pathological effects of ALS-associated mutations compared to wild type TDP-43 due to inadequate control over expression levels
Solution Approach 1:
The patent changes the expression level parameter by using heterozygous knock-in mice that express mutant TDP-43 at endogenous levels rather than overexpression. This allows accurate assessment of pathological effects by maintaining physiological expression control while still exhibiting disease phenotypes.
2Reliability
If transgenic mouse models overexpress mutant TDP-43, then they exhibit hallmarks of TDP-43 proteinopathies including mislocalization and aggregate formation, but overexpression of wild type TDP-43 can also cause FTLD-TDP-like or ALS-like pathogenesis
Solution Approach 1:
The patent applies local quality by introducing a specific point mutation (N390D) at a defined location in the TDP-43 protein sequence while maintaining the rest of the protein structure and expression regulation identical to wild type. This allows selective study of mutation-specific effects without confounding overexpression artifacts.
Solution Approach 2:
The patent creates a faithful copy of the human ALS-associated N390D mutation in the mouse Tardbp gene through homologous recombination, preserving the exact amino acid substitution found in human patients while maintaining mouse genomic context and regulation.
3Device complexity
If homologous knock-in of ALS-FTD associated TDP-43 mutation is performed, then a mouse model can be constructed with controlled expression, but the exhibited ALS-FTD like phenotype is subtle
Solution Approach 1:
The patent uses heterozygous knock-in (one mutant allele and one wild type allele) to achieve partial expression of mutant TDP-43 at endogenous levels. This partial action approach generates sufficient pathological phenotype for study while maintaining physiological expression control, avoiding the subtlety problem of previous heterozygous models.
Data Source
AI summary
The invention relates to a genetically modified mouse comprising a heterozygous mutation of Tardbp (TDP-43) gene in that the Asn at amino acid 390 in TDP-43 is substituted with an amino acid that is different from Asn, wherein the genetically modified mouse exhibits Amyotrophic lateral sclerosis (ALS)-like phenotypes, TDP-43 proteinopathies and/or motor neuron degeneration. The invention also so relates to an isolated spinal cord motor neuron differentiated from an embryonic stem cell (ESC) that is obtained from an offspring of a genetically modified mouse according to the invention. Methods for identifying an agent alleviating and/or suppressing ALS-TDP pathogenesis are also disclosed.