Neuronal subtype-specific ribosomal protein mRNA expression

Current understanding recognizes that ribosomal proteins (RPs) have regulatory roles beyond their canonical structural functions in translation, raising the question of how their expression is organized across cell types. Given the diversity of neuronal cell types, understanding RP gene expression at the neuronal subtype level is an important and previously inaccessible question. Here, leveraging advances in single-cell transcriptomics, we analyzed single-cell RNA-seq data sets from the mouse cerebral cortex and hippocampus to examine RP mRNA expression across neuronal subtypes. We observed distinct RP mRNA expression profiles between excitatory and inhibitory neurons and found that higher Rps27 transcript levels in inhibitory neurons corresponded to increased RPS27 protein abundance. Beyond excitatory-inhibitory differences, RP mRNA expression further segregated across well-defined neuronal subclasses, with 59 of 84 RP genes differentially expressed, including enrichment of Rpl21 in Lamp5 and Rps27 in Vip interneurons. These patterns were consistent across cortical regions and reproducible across two independent single-cell technologies (Smart-seq2 and 10x Genomics). Analysis of aging- and stress-associated data sets revealed stable RP expression signatures, with limited phenotype-linked changes. Together, we present a comprehensive atlas of ribosomal protein gene expression at neuronal subclass resolution, revealing robust subclass-specific transcriptional signatures, suggesting an underestimated regulatory layer.