Cellular Taxonomy of the Mouse Striatum as Revealed by Single-Cell RNAseq

The striatum contributes to many cognitive processes and disorders, but its cell types are incompletely characterized. We show that microfluidic and FACS-based single-cell RNA sequencing of mouse striatum provides a well-resolved classification of striatal cell type diversity. Transcriptome analysis revealed 10 differentiated distinct cell types, including neurons, astrocytes, oligodendrocytes, ependymal, immune, and vascular cells, and enabled the discovery of numerous novel marker genes. Furthermore, we identified two discrete subtypes of medium spiny neurons (MSN) which have specific markers and which overexpress genes linked to cognitive disorders and addiction. We also describe continuous cellular identities, which increase heterogeneity within discrete cell types. Finally, we identified cell type specific transcription and splicing factors that shape cellular identities by regulating splicing and expression patterns. Our findings suggest that functional diversity within a complex tissue arises from a small number of discrete cell types, which can exist in a continuous spectrum of functional states. We measured the transcriptome of 1208 single striatal cells using two complementary approaches; microfluidic single-cell RNAseq (Mic-scRNAseq) and single cell isolation by FACS (FACS-scRNAseq) (Table S1). We sampled cells either randomly or enriched specifically for MSNs or astrocytes using FACS from D1- tdTomato (tdTom)/D2-GFP or Aldhl1-GFP mice, respectively