Highly sensitive and scalable time-resolved RNA sequencing in single cells with scNT-seq2.

Understanding gene expression dynamics requires resolving newly synthesized RNAs from pre-existing pools at single-cell resolution. Here, we present scNT-seq2, a highly sensitive and scalable method for time-resolved single-cell RNA sequencing. By systematically optimizing the second-strand cDNA synthesis (2(nd) SS) step, we substantially improved read alignment rates, reduced background mutations, and enhanced library complexity compared to the original scNT-seq (1). Benchmarking in 4sU-labeled K562 cells demonstrated that scNT-seq2 accurately quantifies newly synthesized transcripts and preserves the gene level RNA turnover. The enhanced sensitivity enables robust detection of dynamic, cell-cycle state specific genes, such as S-phase regulators. Together, scNT-seq2 provides an efficient and versatile tool for dissecting transcriptional dynamics across diverse biological systems at single-cell resolution.