CAPRIN1-linked neurodevelopmental disorder: understanding the role of CAPRIN1 loss on neuronal differentiation, neurogenesis, and proliferation.

Background/Objectives: We recently discovered that CAPRIN1 loss-of-function variants are associated with an autosomal dominant neurodevelopmental disorder. In neurons derived from hiPSCs haploinsufficient for CAPRIN1, we observed both structural and functional abnormalities. Transcriptome analysis revealed impairments in several cellular processes, including cell cycle control and proliferation, DNA replication, translation, oxidative phosphorylation, neurogenesis and neuronal outgrowth. We aimed to further investigate the role of CAPRIN1 in determining the fate of neurons, and to uncover the underlying pathogenic mechanisms. Methods: We generated forebrain cortical organoids (fBOs) using CAPRIN1 patient-derived hiPSCs. We analysed fBO cellular architecture and composition, and neuronal activity using immunofluorescence analysis, multicolor immunophenotyping panels and metabolic studies. Results: During the development of CAPRIN1 fBOs, we observed a significant decrease in their overall size and abnormal morphology. Our preliminary findings show that the loss of CAPRIN1 leads to impaired cell proliferation and cell cycle regulation, as well as an imbalance in the composition of fBOs. Specifically, we observed an overrepresentation of immature neurons and glial cells. Since these cells primarily rely on glycolysis, β-oxidation, and redox signalling for their metabolism, we are performing metabolic analyses. Initial results suggest an increase in glycolysis and an increase in reactive oxygen species. Conclusion: The development and investigation of CAPRIN1 fBOs are beginning to provide insights into the involvement of CAPRIN1 in neuronal differentiation, neurogenesis and proliferation, with a focus on its role in regulating protein translation. Additionally, this study will emphasize the similarities between CAPRIN1 and its main interactor, FMRP, associated with the Fragile-X-syndrome.