Figure 6.
Pituitary Target Organ Ablation Induces Differentiation of Adult SOX9-Positive Stem Cells
Adrenalectomies were performed 24 hr after the last tamoxifen administration (5 mg/25 g/day for 5 days). Pituitaries were harvested 1 week later.
(A) ACTH-positive corticotrophs were counted on two sections/animal and the surface area of the sections was measured. We observed significantly more corticotrophs after adrenal ablation (p = 0.023).
(B) We almost exclusively observe EYFP;ACTH-double-positive corticotrophs after adrenalectomies in Sox9ires-CreERT2/+;R26REYFP/+ animals (adrenalectomy n = 5, 2 females and 3 males, sham-operated n = 5, 3 females and 2 males, p = 0.0005, with no difference found between males and females).
(C) Double immunofluorescence illustrating the differentiation of EYFP+ve SOX9 progenitors in ACTH+ve corticotrophs in a Sox9ires-CreERT2/+;R26REYFP/+ animal after adrenalectomy. Scale bar: 10 μm.
(D) Proportion of new corticotrophs generated from SOX9+ve progenitors. We first assessed the efficiency of SOX9-IRES-CreERT2 by counting the number of EYFP;SOX9-double-positive cells 48 hr after 5 days of tamoxifen treatment. Eighteen percent (SD = 3.2, n = 3) of SOX9+ve cells were EYFP+ve. We then measured the surface area of all the sections where we counted ACTH;EYFP-double-positive cells in adrenalectomized animals (n = 5). We corrected this number so that it represented 100% and not just the 18% of cells generated from SOX9+ve cells. This amounted to 21 corticotrophs/mm2, representing 19% of the new corticotrophs. Data are presented as mean ± SEM.