Cohen Syndrome Patient iPSC-Derived Neurospheres and Forebrain-Like Glutamatergic Neurons Reveal Reduced Proliferation of Neural Progenitor Cells and Altered Expression of Synapse Genes

Abstract

Cohen syndrome (CS), a rare autosomal recessive disorder, has been associated with genetic mutations in the VPS13B gene, which regulates vesicle-mediated protein sorting and transport. However, the cellular mechanism underlying CS pathogenesis in patient-derived human neurons remains unknown. We identified a novel compound heterozygous mutation, due to homozygous variation of biparental origin and heterozygous variation inherited from the father, in the VPS13B gene in a 20-month-old female patient. To understand the cellular pathogenic mechanisms, we generated induced pluripotent stem cells (iPSCs) from the fibroblasts of the CS patient. The iPSCs were differentiated into forebrain-like functional glutamatergic neurons or neurospheres. Functional annotation from transcriptomic analysis using CS iPSC-derived neurons revealed that synapse-related functions were enriched among the upregulated and downregulated genes in the CS neurons, whereas processes associated with neurodevelopment were enriched in the downregulated genes. The developing CS neurospheres were small in size compared to control neurospheres, likely due to the reduced proliferation of SOX2-positive neural stem cells. Moreover, the number of SV2B-positive puncta and spine-like structures was significantly reduced in the CS neurons, suggesting synaptic dysfunction. Taking these findings together, for the first time, we report a potential cellular pathogenic mechanism which reveals the alteration of neurodevelopment-related genes and the dysregulation of synaptic function in the human induced neurons differentiated from iPSCs and neurospheres of a CS patient.

Genetic mouse models of autism spectrum disorder present subtle heterogenous cardiac abnormalities

“…Enrichment analysis revealed high expression in neurons and oligodendrocytes, involved mainly in synaptic function (Human Protein Atlas, n.d.; Karlsson et al, 2021; Human Protein Atlas: www.proteinatlas.org. Additionally synaptic dysfunction has been identified in iPSCderived neurospheres and forebrain-like glutamatergic neurons of Cohen syndrome patient (Lee et al, 2020). The possible pathway in Shank3 is mentioned above (Boeckers et al, 2002;Jaramillo et al), although it is not clear how the observed effect would differ between Homozygote and Heterozygote cases.…”

Dysfunction of NMDA receptors in neuronal models of an autism spectrum disorder patient with a DSCAM mutation and in Dscam-knockout mice

“…About 300-bp-long fragments were isolated using gel electrophoresis; they were then amplified by PCR and sequenced on Illumina HiSeq X platform in the paired-end sequencing mode (2 × 150 bp reads). Bioinformatic analysis was performed as described previously [ 29 ]. Briefly, raw sequencing reads were aligned to the human genome and differential gene expression analysis was conducted using the DESeq2 method [ 30 ] and genes with at least 1.5-fold changes between groups at a false discovery rate of 5% were defined as differentially expressed genes.…”

Cortical Organoids to Model Microcephaly

“…More recently, recycling and internalization assays in HeLa cells have shown another role of VPS13B in transport from early endosomes to recycling endosomes via an interaction with Stx6- and Stx13-containing vesicles [ 67 ]. In a recent study by Lee et al, patient-derived iPSCs were differentiated into either forebrain-like glutamatergic excitatory neurons in 2D cultures or 3D neurospheres using dual SMAD inhibition [ 68 ]. While a transcriptomic analysis on glutamatergic neurons obtained in 2D revealed alterations of the genes involved in synaptic function, the 3D protocol did not consider stages beyond 18 days, and could thus not confirm the 2D findings.…”