Fig. 3: Pubertal Gpr125+ cells are long-lived unipotent basal progenitors.
From: Gpr125 is a unifying hallmark of multiple mammary progenitors coupled to tumor latency
a Genetic strategy used to target tdTomato expression to Gpr125/Adgra3-expressing cells and their progeny. b Schematic illustrating strategy to trace the lineage of cells that express Gpr125 during early puberty by delivering Tamoxifen (Tam) to (5w) nulliparous mice and harvesting glands during late puberty (7w), pregnancy (P15); lactation (L6), and in aged and multiparous mice. c Representative 3D-imaging of mammary gland nipple-proximal region of Adgra3-CreERT2;tdT mice analyzed 2 weeks after labeling. d–g tdT+ cells with immunolocalization (green) of basal markers K5, K14, SMA, and p63, and exclusion of luminal markers Ecad, K8 (h, i). j tdT+ cells in the cap cell layer of TEB and subtending duct with immunolocalization of basal K5 (k) and exclusion of luminal Ecad (l). m p15 Immature alveoli show basally located tdT+ cells that express K5, but lack K8 expression (n). o tdT+ cells form characteristic basket-like morphology of mature myoepithelial cells enmeshing an Ecad+ alveolus in the lactating mammary gland. p–r Extensive strips of tdT+ cells remain along the outer basal layer of ducts in aged mice (p, q) and after multiple pregnancies (r). Scale bar = 50 µm. tdT = red, tdT+ cells; DAPI = blue nuclear staining. Two glands from each of the five mice were analyzed/stage.
