Speaker
Description
Klinefelter syndrome (KS, 47,XXY) is the most prevalent aneuploidy in males (1:400-1:600). High-grade sex chromosome aneuploidies (HGA-SCAs), such as 48,XXXY, and 49,XXXXY are rarer conditions occurring in 1:40.000-1:80.000 males. KS and HGA-SCA patients exhibit a broad spectrum of neuronal impairment, including cognitive deficits, seizures, autistic traits, and motor, speech, and language delays. While KS patients typically display a milder phenotype, HGA-SCAs are associated with profound cognitive defects. Despite the prevalence of X chromosome aneuploidies, there is a critical need for cellular models to define the transcriptional, epigenetic, and functional consequences of X chromosome overdosage during neurodevelopment. To this end, we derived cortical organoids from 47,XXY, 48,XXXY, and 49,XXXXY iPSCs. Allele-specific expression (ASE) analysis on X aneuploid organoids demonstrated a preserved epigenetic X inactivation status at different time points, from one to 12 months of differentiation in vitro. Through a multi-layered analysis integrating morphological, functional, bulk, and single-cell transcriptomics, we found that the additional X chromosomes lead to impaired neural patterning, disrupted cortical architecture, and altered electrophysiological properties of cortical organoids in a dose-dependent manner. While 47,XXY organoids are phenotypically and functionally similar to 46,XY controls, HGA-SCAs display severe functional defects and aberrant transcriptomes. Through single-cell RNA analysis, we profiled the genes that escape X inactivation in neuronal and non-neuronal cell populations and revealed a dysregulated proliferation of neural progenitor in organoids carrying supernumerary X chromosomes. Additionally, severe astrocyte differentiation defects were observed in HGA-SCAs organoids, potentially contributing to synaptic dysfunction. Moreover, high-density microelectrode arrays (MEA) analysis revealed a higher mean spike firing rate and amplitude of HGA-SCAs compared to 46,XY organoids. Finally, patch-clamp studies demonstrated significant hyperexcitability of HGA-SCA organoids and X dosage-sensitive deficits in long-term potentiation (LTP). Our work leveraged the inaugural cohort of X aneuploid cortical organoids to unravel the functional consequences of X-linked gene overdosage during neurodevelopment.
| Author(s) | Veronica Astro*1, Angels Almenar2, Rawan Alghamdi1, Kelly J. Cardona-Londoño1, Gabriel Herrera Lopez1, Ivan G. Bassets3, Pierre Magistretti1, Alysson Muotri2 and Antonio Adamo1 |
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| Affiliation(s) | "1 Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia. 2 Department of Pediatrics/Rady Children’s Hospital San Diego, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA. 3 Universal Sequencing Technology, San Diego, La Jolla, CA, 92093, USA." |
