TUBG1 missense variants underlying cortical malformations disrupt neuronal locomotion and microtubule dynamics but not neurogenesis

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Ivanova, Ekaterina | Gilet, Johan | Sulimenko, Vadym | Duchon, Arnaud | Rudolf, Gabrielle | Runge, Karen | Collins, Stephan | Asselin, Laure | Broix, Loic | Drouot, Nathalie | Tilly, Peggy | Nusbaum, Patrick | Vincent, Alexandre | Magnant, William | Skory, Valerie | Birling, Marie-Christine | Pavlovic, Guillaume | Godin, Juliette | Yalcin, Binnaz | Hérault, Yann | Dráber, Pavel | Chelly, Jamel | Hinckelmann, Maria-Victoria

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International audience. De novo heterozygous missense variants in the γ-tubulin gene TUBG1 have been linked to human malformations of cortical development associated with intellectual disability and epilepsy. Here, we investigated through in-utero electroporation and in-vivo studies, how four of these variants affect cortical development. We show that TUBG1 mutants affect neuronal positioning, disrupting the locomotion of new-born neurons but without affecting progenitors' proliferation. We further demonstrate that pathogenic TUBG1 variants are linked to reduced microtubule dynamics but without major structural nor functional centrosome defects in subject-derived fibroblasts. Additionally, we developed a knock-in Tubg1Y92C/+ mouse model and assessed consequences of the mutation. Although centrosomal positioning in bipolar neurons is correct, they fail to initiate locomotion. Furthermore, Tubg1Y92C/+ animals show neuroanatomical and behavioral defects and increased epileptic cortical activity. We show that Tubg1Y92C/+ mice partially mimic the human phenotype and therefore represent a relevant model for further investigations of the physiopathology of cortical malformations.

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