C-terminal proline deletions in KCNC3 cause delayed channel inactivation and an adult-onset progressive SCA13 with spasticity.

Abstract

Mutations in the potassium channel gene KCNC3 (Kv3.3) cause the autosomal dominant neurological disease, spinocerebellar ataxia 13 (SCA13). In this study, we expand the genotype-phenotype repertoire of SCA13 by describing the novel KCNC3 deletion p.Pro583_Pro585del highlighting the allelic heterogeneity observed in SCA13 patients. We characterize adult-onset, progressive clinical symptoms of two afflicted kindred and introduce the symptom of profound spasticity not previously associated with the SCA13 phenotype. We also present molecular and electrophysiological characterizations of the mutant protein in mammalian cell culture. Mechanistically, the p.Pro583_Pro585del protein showed normal membrane trafficking with an altered electrophysiological profile, including slower inactivation and decreased sensitivity to the inactivation-accelerating effects of the actin depolymerizer latrunculin B. Taken together, our results highlight the clinical importance of the intracellular C-terminal portion of Kv3.3 and its association with ion channel function.

• Authors: Swati Khare, Kira Galeano, Yalan Zhang, Jerelyn A Nick, Harry S Nick, S H Subramony, Jacinda Sampson, Leonard K Kaczmarek, Michael F Waters
• Journal: Cerebellum (London, England) (Cerebellum) Vol. 17 Issue 5 Pg. 692-697 (Oct 2018) ISSN: 1473-4230 [Electronic] United States
• PMID: 29949095 (Publication Type: Case Reports, Journal Article)

Chemical References

• Bridged Bicyclo Compounds, Heterocyclic
• KCNC3 protein, human
• Marine Toxins
• Shaw Potassium Channels
• Thiazolidines
• latrunculin B

Topics

• Adult
• Animals
• Bridged Bicyclo Compounds, Heterocyclic (pharmacology)
• CHO Cells
• Cricetulus
• Female
• Humans
• Male
• Marine Toxins (pharmacology)
• Membrane Potentials (drug effects, physiology)
• Muscle Spasticity (diagnostic imaging, genetics, physiopathology)
• Phenotype
• Sequence Deletion
• Shaw Potassium Channels (genetics)
• Spinocerebellar Ataxias (congenital, diagnostic imaging, genetics, physiopathology)
• Thiazolidines (pharmacology)