An integrative single-cell transcriptomic atlas of the postnatal mouse mammary gland allows discovery of new developmental trajectories in the luminal compartment

GARCÍA SOLÁ MARTÍN; STEDILE MICAELA; BECKERMAN INÉS; KORDON EDITH

CABA

Simposio; BA-BCS 2021; 2021

The mammary gland (MG) is a highly dynamicorgan which undergoes periods of expansion, differentiationand cell death in each reproductive cycle.In agreement with the dynamic nature of the gland,mammary epithelial cells (MECs) are extraordinarilyheterogeneous. Single cell RNA-seq (scRNA-seq)analyses have contributed to understand the cellularand transcriptional heterogeneity of this complex tissue.Here, we integrate scRNA-seq data from threefoundational reports that have explored the MG cellpopulations throughout development at single-celllevel. We focused our analysis on MG post-nataldevelopment. This new integrated study correspondsto RNA sequences from a total of 53,686 individualcells. The large volume of information provides newinsights, as a better resolution of the previously detectedProcr+ stem-like cell subpopulation. Moreover,our study proposes new pseudo-temporal trajectoriesof MEC populations at two resolution levels, eitherconsidering all mammary cell subtypes or focusingspecifically on the luminal lineages. Interestingly, theluminal-restricted analysis reveals distinct expressionpatterns for different millk-protein genes, suggestingspecific and non-redundant roles for each of theseproteins. In summary, our data show that the applicationof bioinformatic tools to integrate multiplescRNA-seq data-sets helps to describe and interpretthe high level of p lasticity involved in gene expressionregulation throughout MG post-natal development.