Dysregulation of global mRNA splicing in a Huntington’s disease neuronal differentiation cell line model

To study cell type- and HTT CAG length-dependent transcriptional and alternative splicing changes associated with HD, we conducted deep RNA-sequencing analysis on human embryonic stem cells (hESC), NPC and neuron cell lines (ESC and NPC, NEU) expressing wild-type (27/ and 30 CAG repeats), 45 CAG (45Q; representing 45 polyQ mutant HTT protein) and 81 CAG (81Q) repeat expansion HTT gene (n=3). The cell lines were derived from an isogenic HTT CAG repeat expansion allelic cell line panel (IsoHD) where hESC H9 cells were genetically modified with monoallelic knockin of expanded CAG tract in exon 1 of HTT representing early onset (45Q) and late onset (81Q) HD, with the 27Q/30Q genotype as healthy control phenotype (Ooi et al., 2019). The sequencing experiment generated 2.9 billion pairs of 150 bp paired-end reads from 27 samples (3 clones, 3 genotypes, 3 cell lines), with 80 to 110 million read pairs per sample. Transcriptome alignment yielded 75 to 100 million uniquely mapped read pairs across all samples. Whole transcriptome profiling analysis of RNA-seq data for hESC, NPC, and neurons expressing either wild-type HTT, 45 CAG repeat HTT, or 81 CAG repeat HTT