Single Cell RNA sequencing of embryonic mouse brain at embryonic day 13.5 and 15.5

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 NDE1 loss -of -function in NDE1 leads to microcephaly-related malformations of cortical development (MCDs), NDEL1 variants have not been founddetected in MCD patients. Here, we identified two patients with pachygyria, andwith or without subcortical band heterotopia (SBH), carrying the same a the first de novo lissencephaly-associatedsomatic mosaic NDEL1 variant, p.Arg105Pro (p.R105P), in two patients who presented with pachygyria and subcortical heterotopia. Through single-cell RNA sequencing and spatial transcriptomice analysis, we observed complementary expression of Nde1/NDE1 and Ndel1/NDEL1 in neural progenitors and postmitotic 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. These cellular and molecular dysfunctions may underlie the pathogenesis of lissencephaly. This study identifies the first lissencephaly-associated NDEL1 variants andese results also sheds light on the distinct roles of NDE1 and NDEL1 in nucleokinesis and MCD pathogenesis.