Single-Cell Exon Deletion Profiling Reveals Splicing Events That Shape Gene Expression and Cell State Dynamics [ChIP-Seq]
Alternative splicing is a pervasive gene regulatory mechanism critical for diversifying the human proteome. To systematically investigate its role in cell fate determination, we developed scCHyMErA-Seq, a scalable CRISPR-based exon deletion screening platform integrated with 10x Genomics single-cell transcriptomic readouts. This tool enables efficient exon deletion while simultaneously capturing Cas9/Cas12a guides and polyadenylated transcripts at single-cell resolution. Applying scCHyMErA-Seq to high-throughput profiling of alternative cassette exons, we identified numerous exons with strong regulatory effects on gene expression. Analysis of NRF1 alternative exon-7 revealed that this exon modulates NRF1 transcriptional activity by regulating its recruitment to the promoters of target genes. Importantly, gene expression profiles generated using scCHyMErA-Seq accurately recapitulate findings from traditional, labor-intensive orthogonal methods, while offering enhanced scalability and efficiency. Overall, scCHyMErA-Seq represents a robust and versatile platform for systematically unraveling the functional impact of alternative splicing by directly linking specific splicing variants to transcriptional phenotypes. Overall design: ChIP-sequencing was conducted in HEK293 Flp-In cells stably expressing FLAG-tagged full-length (FL) and ?Exon-7 NRF1 isoforms. Immunoprecipitation was performed using FLAG antibodies, with HEK293 cells expressing FLAG-EGFP serving as a negative control.