Novel lissencephaly-associated NDEL1 variant reveals distinct roles of NDE1 and NDEL1 in nucleokinesis and human cortical malformations

The development of the cerebral cortex involves a series of dynamic events, including cell proliferation and migration, which rely on the motor protein dynein and its regulators NDE1 and NDEL1. While the loss of function in NDE1 leads to microcephaly-related malformations of cortical development (MCDs), NDEL1 variants have not been detected in MCD patients. Here, we identified two patients with pachygyria, with or without subcortical band heterotopia (SBH), carrying the same de novo somatic mosaic NDEL1 variant, p.Arg105Pro (p.R105P). Through single-cell RNA sequencing and spatial transcriptomic analysis, we observed complementary expression of Nde1/NDE1 and Ndel1/NDEL1 in neural progenitors and post-mitotic neurons, respectively. Ndel1 knockdown by in utero electroporation resulted in impaired neuronal migration, a phenotype that could not be rescued by p.R105P. Remarkably, p.R105P expression alone strongly disrupted neuronal migration, increased the length of the leading process, and impaired nucleus-centrosome coupling, suggesting a failure in nucleokinesis. Mechanistically, p.R105P disrupted NDEL1 binding to the dynein regulator LIS1. This study identifies the first lissencephaly-associated NDEL1 variant and sheds light on the distinct roles of NDE1 and NDEL1 in nucleokinesis and MCD pathogenesis.