Deep transcriptomics reveals cell-specific isoforms of pan-neuronal genes

Profiling alternative splicing in single neurons using RNA-seq is challenging due to low capture efficiency and sensitivity. We therefore know much less about splicing patterns and regulation across neurons than we do about gene expression. Here we leverage unique attributes of C. elegans to investigate deep neuron-specific transcriptomes with biological replicates generated by the CeNGEN consortium, enabling high-confidence assessment of splicing across neuron types even for lowly-expressed genes. Global splicing maps reveal several striking observations, including pan-neuronal genes harboring cell-specific splice variants, and abundant differential intron retention across neuron types. We develop an algorithm to identify unique cell-specific expression patterns, which reveals both cell-specific isoforms and potential regulatory factors establishing these isoforms. Genetic interrogation of these factors in vivo identifies three distinct splicing factors employed to control splicing in a single neuron. Finally, we develop a user-friendly platform for spatial transcriptomic visualization of these splicing patterns with single-neuron resolution.