Isogenic Wild Type and iPSC-Derived CTBP1 Mutant Neuronal Cells Exhibit Neurodevelopmental Defects

Hypotonia, ataxia, developmental delay and tooth enamel defect syndrome (HADDTS) is a recently identified syndrome linked to a heterozygous mutation in the C-Terminal Binding Protein 1 (CTBP1) transcriptional corepressor. The mutation is located within the major binding cleft (PXDLS), crucial for CtBP1’s interaction with proteins that regulate gene expression. We generated isogenic induced pluripotent cell lines (iPSCs) with the CTBP1 mutation in heterozygous and homozygous using CRISPR/Cas9 editing method. The transcriptional profile of iPSC-derived early neurons from isogenic wild-type and CTBP1 heterozygous and homozygous mutants was determined by RNA sequencing. The RNA-Seq data revealed downregulation of several key transcriptional factors, with homozygous mutations causing more pronounced downregulation than heterozygous mutations. Isogenic mutant neural stem cells (NSCs) exhibited less adhesion, migration, and calcium dysregulation, and mutant neurons showed premature neurite outgrowth. Our transcriptome and biological results provide novel insight into the mechanism of CTBP1 p.R342W mutation's role in the defective neurodevelopmental process.