SCNM1, a putative RNA splicing factor that modifies disease severity in mice

Area of Science:

• Genetics
• Neuroscience
• Molecular Biology

Background:

• Inherited disorder severity is influenced by genetic background.
• A specific genetic interaction in C57BL/6J mice transforms a chronic movement disorder into a lethal neurological disease.

Purpose of the Study:

• To investigate a modifier interaction in mice that exacerbates an inherited neurological disorder.
• To identify the genetic basis of this modifier interaction and its molecular mechanism.

Main Methods:

• Utilized C57BL/6J mice with a primary mutation (medJ) in the Scn8a (Nav1.6) sodium channel gene.
• Identified a modifier mutation in the SCNM1 gene, a putative RNA splicing factor.
• Analyzed the impact of the SCNM1 mutation on sodium channel transcript splicing and abundance.

Main Results:

• The modifier mutation in SCNM1 introduces a nonsense codon and causes exon skipping, leading to reduced functional SCNM1 protein.
• This disruption in SCNM1 function reduces the abundance of correctly spliced Scn8a transcripts below a critical survival threshold.
• The interaction converts a chronic movement disorder into a lethal neurological condition.

Conclusions:

• Genetic variation in RNA splicing factors can significantly influence disease susceptibility and severity.
• This mouse model provides insights into how modifier genes impact inherited neurological disorders.
• The findings suggest similar mechanisms may operate in human inherited diseases.