C698R mutation in Lrsam1 gene impairs nerve regeneration in a CMT2P mouse model
Daniel Moiseev1, Zafar Wazir1, Donghao Liu1
1Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA.
Abstract:
Missense mutation C694R in the RING domain of the LRSAM1 gene results in a dominantly inherited polyneuropathy, Charcot-Marie-Tooth disease type 2P (CMT2P). We have generated and characterized a Lrsam1C698R knock-in mouse model produced through CRISPR/Cas9 technology. Both heterozygous (Lrsam1+/C698R) and homozygous (Lrsam1C698/C698R) knock-in mice exhibited normal motor functions on behavioral tests as well as normal on nerve conduction studies. Axonal density and myelin thickness were not significantly different between mutants and wild-type mice by sciatic nerve morphometric analysis up to 17 months of age. In line with these normal findings, protein-protein interactions between mutant LRSAM1 and RNA-binding proteins (such as FUS and G3BP1) were still present in mouse cells, which differs from the disrupted interactions between these proteins in human CMT2P cells. However, after crush nerve injury, Lrsam1+/C698R mice had a mild, but statistically significant, reduced compound nerve action potential and conduction velocity during recovery. Therefore, C698R mutation results in a mild impaired nerve regeneration in mice. We speculate that repetitive nerve injuries may, at least partially, contribute to the slowly progressive axonal loss in CMT2P.
Insights
The LRSAM1 C698R mutation causes mild nerve regeneration impairment in mice, potentially contributing to Charcot-Marie-Tooth disease type 2P (CMT2P) progression after nerve injury.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Charcot-Marie-Tooth disease type 2P (CMT2P) is a dominantly inherited polyneuropathy linked to LRSAM1 gene mutations.
- The specific missense mutation C694R in the LRSAM1 RING domain is associated with CMT2P.
Purpose of the Study:
- To generate and characterize a mouse model for the LRSAM1 C698R mutation.
- To investigate the impact of the LRSAM1 C698R mutation on motor function, nerve structure, and regeneration.
Main Methods:
- CRISPR/Cas9 technology was used to create Lrsam1 C698R knock-in mice.
- Behavioral tests, nerve conduction studies, and sciatic nerve morphometric analysis were performed.
- Protein-protein interactions were assessed in mouse cells and compared to human CMT2P cells.
Main Results:
- Lrsam1 C698R knock-in mice (heterozygous and homozygous) showed normal motor function and nerve structure up to 17 months.
- Protein interactions between mutant LRSAM1 and RNA-binding proteins remained intact in mouse cells.
- Mildly impaired nerve regeneration, evidenced by reduced compound nerve action potential and conduction velocity, was observed after crush nerve injury in heterozygous mice.
Conclusions:
- The C698R mutation in Lrsam1 leads to a subtle defect in nerve regeneration in mice.
- Repetitive nerve injuries may contribute to the progressive axonal loss observed in CMT2P patients.
