Novel lissencephaly-associated DCX variants in the C-terminal DCX domain affect microtubule binding and dynamics

Jun Ru Lin, Ju Fang Cheng, Yo Tsen Liu, Ting Rong Hsu, Kao Min Lin, Chien Chen, Chia Ling Lin, Meng Han Tsai, Jin Wu Tsai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Objective: Pathogenic variants in DCX on the X chromosome lead to lissencephaly and subcortical band heterotopia (SBH), brain malformations caused by neuronal migration defects. Its product doublecortin (DCX) binds to microtubules to modulate microtubule polymerization. How pathogenic DCX variants affect these activities remains not fully investigated. Methods: DCX variants were identified using whole exome and Sanger sequencing from six families with lissencephaly/SBH. We examined how these variants affect DCX functions using microtubule binding, regrowth, and colocalization assays. Results: We found novel DCX variants p.Val177AlafsTer31 and p.Gly188Trp, as well as reported variants p.Arg196His, p.Lys202Met, and p.Thr203Ala. Incidentally, all of the missense variants were clustered on the C-terminal DCX domain. The microtubule binding ability was significantly decreased in p.Val177AlafsTer31, p.Gly188Trp, p.Lys202Met, and previously reported p.Asp262Gly variants. Furthermore, expression of p.Val177AlafsTer31, p.Gly188Trp, p.Arg196His, p.Lys202Met, and p.Asp262Gly variants hindered microtubule growth in cells. There were also decreases in the colocalization of p.Val177AlafsTer31, p.Thr203Ala, and p.Asp262Gly variants to microtubules. Significance: Our results indicate that these variants in the C-terminal DCX domain altered microtubule binding and dynamics, which may underlie neuronal migration defects during brain development.

Original languageEnglish
JournalEpilepsia
DOIs
StateAccepted/In press - 2022

Keywords

  • DCX
  • doublecortin
  • epilepsy
  • lissencephaly
  • microtubule binding protein
  • neuronal migration
  • subcortical band heterotopia

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