Steroid receptor coactivator‐2 drives epithelial reprogramming that enables murine embryo implantation

Abstract

Although we have shown that steroid receptor coactivator‐2 (SRC‐2), a member of the p160/SRC family of transcriptional coregulators, is essential for decidualization of both human and murine endometrial stromal cells, SRC‐2's role in the earlier stages of the implantation process have not been adequately addressed. Using a conditional SRC‐2 knockout mouse (SRC‐2d/d) in timed natural pregnancy studies, we show that endometrial SRC‐2 is required for embryo attachment and adherence to the luminal epithelium. Implantation failure is associated with the persistent expression of Mucin 1 and E‐cadherin on the apical surface and basolateral adherens junctions of the SRC‐2d/d luminal epithelium, respectively. These findings indicate that the SRC‐2d/d luminal epithelium fails to exhibit a plasma membrane transformation (PMT) state known to be required for the development of uterine receptivity. Transcriptomics demonstrated that the expression of genes involved in steroid hormone control of uterine receptivity were significantly disrupted in the SRC‐2d/d endometrium as well as genes that control epithelial tight junctional biology and the emergence of the epithelial mesenchymal transition state, with the latter sharing similar biological properties with PMT. Collectively, these findings uncover a new role for endometrial SRC‐2 in the induction of the luminal epithelial PMT state, which is a prerequisite for the development of uterine receptivity and early pregnancy establishment.

Establishment of Murine Pregnancy Requires the Promyelocytic Leukemia Zinc Finger Transcription Factor

“…injection of human chorionic gonadotropin (hCG; Sigma-Aldrich (5 IU/100 μL of sterile 0.9% saline)). Sixteen hours later, oocytes were harvested from the lumen of the fallopian tubes and counted using a dissecting microscope as previously detailed [ 84 ]. Using fallopian tube tissue that was dissected from Plzf f/f and Plzf d/d females at GD 2, two-cell stage embryos were retrieved by gently flushing the fallopian tube lumen with 100 μL of sterile phosphate-buffered saline (PBS).…”

“…Using fallopian tube tissue that was dissected from Plzf f/f and Plzf d/d females at GD 2, two-cell stage embryos were retrieved by gently flushing the fallopian tube lumen with 100 μL of sterile phosphate-buffered saline (PBS). To visualize emerging implantation sites along both uterine horns of mice at GD5, a Chicago sky blue dye solution (1% in PBS; 100 μL per mouse) was injected into one lateral tail vein before mice were euthanized 2–5 min later [ 84 ]; stained reproductive tract tissues were removed first for the purposes of imaging and subsequent cellular and molecular analyses.…”

“…Following overnight fixation in 4% paraformaldehyde, tissues were stepwise dehydrated by sequential incubation in increased concentrations of ethanol; dehydrated and fixed tissues were cleared with xylene before paraffin embedding. Paraffin-embedded tissues were sectioned to 5 μm thickness onto slides before tissue sections were stained with hematoxylin and eosin (H&E) for general histological analysis [ 84 , 85 ]. Immunohistochemical visualization of PLZF protein was achieved using an anti-PLZF primary mouse monoclonal antibody (D-9 [ 86 ]; Santa Cruz Biotechnology Inc., Dallas, TX, USA, #sc-28319, 1:150 dilution) in combination with the Mouse on Mouse (M.O.M.)…”