Adrenomedullin Enhances Endometrial Receptivity: Insights Into Cytoskeletal Reorganization and Pinopode Formation

Anna L.S. Beeson¹; Margeaux W. Marbrey²; Meredith F. Gillis¹; Bryan Kistner¹; Audrey Garneau¹; Kathleen M. Caron¹

1. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, USA

2. Department of Obstetrics and Gynecology, Duke University, Durham, USA

 

Abstract Text: Failure of a healthy blastocyst to implant in a receptive endometrium accounts for a significant portion of early pregnancy losses. Despite this barrier to fertility therapeutics, mechanisms governing endometrial receptivity remain poorly understood. We previously found that in mice, intrauterine administration of adrenomedullin (AM) before blastocyst transfer improved implantation rates and increased pinopode size and uterine surface coverage. Maternal haploinsufficiency for AM led to decreased uterine receptivity, evident in subfertility phenotypes and reduced epithelial pinopode coverage. To identify genes differentially expressed upon AM treatment, we treated mice expressing uterine epithelium-specific RiboTag with either AM or vehicle and compared the ribosome-associated mRNA profiles. Among the top 35 up- and down-regulated genes (p < 0.05, 1-way ANOVA Bonferroni correction), we observed significant changes in many genes with well-documented roles in cytoskeletal reorganization and actin-myosin dynamics such as Fermt1, Ank3, Tubb3, and Arpc1a. Preliminary results show that treating human endometrial epithelial-like Ishikawa cells with AM trends towards peripheral F-actin arrangement (p=0.06, 1-way ANOVA Tukey correction), consistent with AM-induced cytoskeletal rearrangement. We are now using murine endometrial organoids to study AM-induced pinopode formation in vitro. Scanning electron microscopy reveals that endometrial organoids treated with 17β-estradiol and medroxyprogesterone acetate display many features seen in mouse endometrial tissue biopsies, including microvilli, cilia, distinct cell borders, and pinopodes. Further studies will use this powerful in vitro technique to explore the cellular mechanisms by which AM induces pinopode formation, focusing on cytoskeletal regulators.