An epilepsy-associated CILK1 variant compromises KATNIP regulation and impairs primary cilia and Hedgehog signaling

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Mutations in human CILK1 (ciliogenesis associated kinase 1) are associated with ciliopathies and epilepsy.
• While kinase domain mutations impair CILK1 function, the impact of mutations outside this domain is less understood.

Approach:

• Generated a knock-in mouse model mimicking the human CILK1 A615T variant found in juvenile myoclonic epilepsy (JME).
• Analyzed primary cilia function, ciliary Hedgehog signaling, and gene expression profiles in mouse embryo fibroblasts (MEFs) with heterozygous or homozygous mutant alleles.
• Investigated the interaction between the CILK1 A615T variant and the scaffold protein KATNIP (katanin-interacting protein).

Key Points:

• A single A612T mutant allele in CILK1 was sufficient to impair primary cilia and ciliary Hedgehog signaling in MEFs.
• Mutant MEFs showed increased ciliation rate, shorter cilia, and altered ciliary gene expression.
• KATNIP regulation of the JME-associated CILK1 variant was compromised, affecting primary cilia maintenance.

Conclusions:

• The CILK1 A615T variant, located outside the kinase domain, disrupts primary cilia function and Hedgehog signaling.
• Compromised KATNIP regulation of this variant contributes to impaired cilia maintenance.
• These findings provide insights into the molecular mechanisms underlying CILK1-associated ciliopathies and epilepsy.