Abstract
The mature cortex contains hugely diverse populations of pyramidal projection neurons (PNs), critical to normal forebrain circuits. In order to understand the healthy cortex, it is essential to characterize this neuronal complexity. We recently demonstrated different identities for
Fezf2
-positive (
Fezf2+ve
) and
Fezf2
-negative (
Fezf2−ve
) intratelencephalic-PNs (IT-PNs) from layer 5 of the motor cortex (M1). Comparatively, each IT-PN type has a distinct electrophysiological phenotype and the
Fezf2+ve
IT-PNs display a unique apical dendritic tuft. Here, we aimed to expand our understanding of the molecular underpinnings defining these unique IT-PN types. Using a validated
Fezf2
-GFP reporter mouse, retrograde labeling techniques and fluorescence activated cell sorting (FACS), combined with a novel approach for low-input RNA-sequencing, we isolated mature
Fezf2+ve
and
Fezf2−ve
IT-PNs for transcriptome profiling. Through the comparison of
Fezf2+ve
and
Fezf2−ve
IT-PN gene expression profiles, we identified significant enrichment of 81 genes in the
Fezf2+ve
IT-PNs and 119 genes in the
Fezf2−ve
IT-PNs. Term enrichment analysis of these enriched genes demonstrated significant overrepresentation of the calcium-binding EF-hand domain in
Fezf2+ve
IT-PNs, suggesting a greater importance for calcium handling in these neurons. Of the
Fezf2−ve
IT-PN enriched genes an unexpected and unique enrichment of genes, previously associated with microglia were identified. Our dataset identifies the molecular profiles of two unique IT-PN types in the mature M1, providing important targets to investigate for their maintenance in the healthy mature brain.