Discovering novel mechanisms of human cortical development & disease using in vivo mouse model and in vitro human-derived cerebral organoids [thesis]

Isabel Yasmin Buchsbaum
2019
This thesis combines three research studies with the common interest of identifying novel mechanisms underlying human cortical development. This aim is pursued from different angles, always basing the investigations on human induced pluripotent stem cell-derived 2D and 3D in vitro model systems that are partly combined with in vivo studies in the developing mouse cortex. Namely, in the pieces of work combined here, we 1) bring to light a neurodevelopmental role of a gene already implicated in
more » ... ady implicated in adult nervous system function, 2) discover a novel mechanism that fine-tunes human neurogenesis, and 3) identify a novel gene whose mutations lead to a malformation of cortical development. The entirety of this work thus adds several aspects to the existing knowledge. In the first study, we identified a neurodevelopmental function of a gene mutated in patients with the progressive gait disorder hereditary spastic paraplegia (HSP). In this group of inherited neurodegenerative diseases, mutations in lipid, mitochondrial, cytoskeletal or transport proteins lead to degeneration of primary motor neurons, which, due to the length of their axons, are particularly sensitive to disruption of these processes. Here, were generated cerebral organoids (COs) derived from HSP patients with mutations in SPG11 coding for spatacsin. Previous work had shown impaired proliferation of SPG11 patient-derived neural progenitor cells (NPCs). We found a proliferation defect also in CO NPCs, leading to a thinner progenitor zone and premature neurogenesis due to increased asymmetric progenitor divisions, along with smaller size of patient-derived COs. Molecularly, we found a decrease in deactivated GSK3β and increase in P-βcatenin at the basis of the observed proliferation/neurogenesis imbalance. We thus confirmed the neurodevelopmental role of SPG11 that had previously been suggested from 2D human in vitro findings. Both the observed reduction in proliferating progenitors and in organoid size were rescued through inhibition of GSK3β, with the Food and [...]
doi:10.5282/edoc.24798 fatcat:5x452etlkfberp764fzilkz5jm