Long-read single cell transcriptomics uncovers isoform preferences in developing human retina

Retinal development has been extensively studied and key transcriptional regulators that drive fate decisions have been identified for major cell classes. These findings were confirmed and deepened in recent years with the advance of single cell RNA sequencing (Scrase). However, many processes that guide progenitor to postmitotic cell differentiation remain elusive, especially since some genes seem to yield different cell populations without apparent correlation with expression level or timing. Here, differential transcript isoform usage might play a role in diversifying the function of developmental genes. In short-read based scRNAseq, isoforms can only be identified if a read maps to a unique sequence or exon junction. However, due to the sparsity and very short reads, these events are extremely rare. We combined a commercial scRNAseq kit, that produces barcoded, full-length cDNA with Oxford Nanopore Technologies based long-read sequencing to generate the first single cell long-read sequencing dataset of fetal human retina. It can help elucidate the role of alternative splicing in retinal development and guide the design of transcript-specific gene therapies for retinal regeneration.