Both gain-of-function and loss-of-function de novo CACNA1A mutations cause severe developmental epileptic encephalopathies in the spectrum of Lennox-Gastaut syndrome

Xiao Jiang, Praveen K. Raju, Nazzareno D'Avanzo, Mathieu Lachance, Julie Pepin, François Dubeau, Wendy G. Mitchell, Luis E. Bello-Espinosa, Tyler M. Pierson, Berge A. Minassian, Jean Claude Lacaille, Elsa Rossignol

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Objective: Developmental epileptic encephalopathies (DEEs) are genetically heterogeneous severe childhood-onset epilepsies with developmental delay or cognitive deficits. In this study, we explored the pathogenic mechanisms of DEE-associated de novo mutations in the CACNA1A gene. Methods: We studied the functional impact of four de novo DEE-associated CACNA1A mutations, including the previously described p.A713T variant and three novel variants (p.V1396M, p.G230V, and p.I1357S). Mutant cDNAs were expressed in HEK293 cells, and whole-cell voltage-clamp recordings were conducted to test the impacts on CaV2.1 channel function. Channel localization and structure were assessed with immunofluorescence microscopy and three-dimensional (3D) modeling. Results: We find that the G230V and I1357S mutations result in loss-of-function effects with reduced whole-cell current densities and decreased channel expression at the cell membrane. By contrast, the A713T and V1396M variants resulted in gain-of-function effects with increased whole-cell currents and facilitated current activation (hyperpolarized shift). The A713T variant also resulted in slower current decay. 3D modeling predicts conformational changes favoring channel opening for A713T and V1396M. Significance: Our findings suggest that both gain-of-function and loss-of-function CACNA1A mutations are associated with similarly severe DEEs and that functional validation is required to clarify the underlying molecular mechanisms and to guide therapies.

Original languageEnglish (US)
Pages (from-to)1881-1894
Number of pages14
JournalEpilepsia
Volume60
Issue number9
DOIs
StatePublished - Sep 1 2019
Externally publishedYes

Keywords

  • CACNA1A
  • Ca2.1
  • Lennox-Gastaut syndrome
  • de novo mutations
  • epilepsy
  • epileptic encephalopathies
  • immunofluorescence
  • patch-clamp
  • structural modeling

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

Fingerprint Dive into the research topics of 'Both gain-of-function and loss-of-function de novo CACNA1A mutations cause severe developmental epileptic encephalopathies in the spectrum of Lennox-Gastaut syndrome'. Together they form a unique fingerprint.

Cite this