A rare missense variant impacting NEK1 kinase function is associated with ALS

Area of Science:

• Genetics and Molecular Biology
• Neuroscience
• Cell Biology

Background:

• Heterozygous loss-of-function (LoF) variants in NEK1 are established causes of amyotrophic lateral sclerosis (ALS).
• NEK1 kinase dysfunction was hypothesized as the primary pathogenic mechanism, but direct evidence linking missense variants to ALS was lacking.
• This study investigates a novel NEK1 missense variant in familial ALS.

Purpose of the Study:

• To identify and functionally characterize a novel NEK1 missense variant associated with ALS.
• To confirm the role of NEK1 kinase activity disruption in ALS pathogenesis.
• To explore the diagnostic and therapeutic implications of NEK1 variants in ALS.

Main Methods:

• Genetic analysis of an ALS pedigree and European ALS cohorts to identify the NEK1 p.N598S variant.
• Functional studies using isogenic human motor neurons comparing p.N598S and truncating variants.
• Assessment of cellular phenotypes including DNA damage, apoptosis, ciliary function, and TDP-43 localization.
• Assay of NEK1 kinase activity and evaluation of pharmacological NEK1 inhibition.

Main Results:

• The NEK1 missense variant p.N598S was identified and co-segregated with ALS in a family, and was enriched in ALS cohorts.
• p.N598S induced ALS-associated cellular phenotypes, including DNA damage, apoptosis, and TDP-43 mislocalization, consistent with NEK1 haploinsufficiency.
• The p.N598S variant impaired NEK1 kinase activity, and pharmacological inhibition mimicked the observed cellular defects.

Conclusions:

• Provides strong genetic and functional evidence that NEK1 kinase disruption is a causative mechanism in NEK1-associated ALS.
• Highlights the importance of kinase activity for NEK1 function in motor neurons.
• Offers implications for interpreting missense variants of uncertain significance and developing targeted ALS therapies.