title: Acidification of uterine epithelium during embryo implantation in mice.
abstract: Uterine luminal epithelium (LE) is essential for establishing uterine receptivity. Previous microarray analysis revealed upregulation of Atp6v0d2 in gestation day 4.5 (D4.5) LE in mice. Realtime PCR showed upregulation of uterine Atp6v0d2 starting right before embryo attachment ∼D4.0. In situ hybridization demonstrated specific uterine localization of Atp6v0d2 in LE upon embryo implantation. Atp6v0d2 encodes one subunit for vacuolar-type H+-ATPase (V-ATPase), which regulates acidity of intracellular organelles and extracellular environment. LysoSensor Green DND-189 detected acidic signals in LE and glandular epithelium upon embryo implantation, correlating with Atp6v0d2 upregulation in early pregnant uterus. Atp6v0d2-/- females had significantly reduced implantation rate and marginally reduced delivery rate from first mating only, but comparable number of implantation sites and litter size compared to control and comparable fertility to control from subsequent matings, suggesting a nonessential role of Atp6v0d2 subunit in embryo implantation. Successful implantation in both control and Atp6v0d2-/- females was associated with uterine epithelial acidification. No significant compensatory upregulation of Atp6v0d1 mRNA was detected in D4.5 Atp6v0d2-/- uteri. To determine the role of V-ATPase instead of a single subunit in embryo implantation, a specific V-ATPase inhibitor bafilomycin A1 (2.5 μg/kg) was injected via uterine fat pad on D3 18:00 h. This treatment resulted in reduced uterine epithelial acidification, delayed implantation, and reduced number of implantation sites. It also suppressed oil-induced artificial decidualization. These data demonstrate uterine epithelial acidification as a novel phenomenon during embryo implantation and V-ATPase is involved in uterine epithelial acidification and uterine preparation for embryo implantation.
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
authors.forename: Shuo
authors.initials: S
authors.lastname: Xiao
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
authors.forename: Ahmed E
authors.initials: AE
authors.lastname: El Zowalaty
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Reproductive Medical Center, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei 442000, China.
authors.forename: Honglu
authors.initials: H
authors.lastname: Diao
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Yongwon
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.|Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Ye
mesh_terms: D000818:Animals; D010064:Embryo Implantation; D004717:Endometrium / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D018942:Macrolides; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*
chemical_list: D018942:Macrolides; C040929:bafilomycin A1; C542312:Atp6v0d2 protein, mouse; D025262:Vacuolar Proton-Translocating ATPases
keywords: Atp6v0d2; V-ATPase; bafilomycin A1; embryo implantation; uterine epithelial acidification; uterine fat pad injection