Fig. 1: snRNA-seq reveals an Anxa1-expressing subtype within Aldh1a1⁺ dopamine neurons.

a, Schematic of snRNA-seq experimental pipeline. b, UMAP reduction of resulting clusters. In total, 15 clusters were found. Notably, four clusters (12, 13, 14 and 15) had weak dopaminergic characteristics (see Extended Data Fig. 3 for details). c, Expression of Aldh1a1 and Anxa1, the latter of which is expressed only within a subset of Aldh1a1-expressing neurons. d, Expression patterns of the additional markers used for genetic access in experiments here, as well as Otx2, a classical marker of most VTA neurons, enriched in clusters 5, 6 and 7. e, Immunofluorescence images of Aldh1a1 and Anxa1 protein expression in SNc (n = 4 mice). Anxa1 expression is limited to a ventral subset of Aldh1a1⁺ neurons. Thresholds for intensity scaling and gamma changes were set for each individual channel to maximize visibility of stained cells. f, Zoomed-in crops of section shown in e. Anxa1 expression was ventrally biased within SNc neurons. g, Right, projection patterns of Anxa1⁺ SNc axons based on viral labeling (n = 4 mice), which appear highly restricted to dorsolateral striatum and patches. Left, projection patterns of Aldh1a1⁺ SNc axons using the same virus (n = 4 mice); projections extend more ventrally relative to Anxa1⁺. Maximum thresholds for image intensity scaling were set to the highest detected pixel intensity in each section to better enable direct comparisons across brains.

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