Bafilomycin A1, a V-ATPase Inhibitor, Inhibits Embryo Implantation via Local Uterine Fat Pad Injection.

Abstract

The vacuolar-type H+-ATPase (V-ATPase) is a multi-subunit intracellular enzyme complex. It is composed of one cytoplasmic peripheral V1 domain for the ATP hydrolysis and one transmebrane integral V0 domain for the proton translocation. The ATP dependent proton transport by V-ATPase controls the intracellular or extracellular acidic environment. Microarray analysis of uterine luminal epithelium (LE) from gestation day 4.5 wild type (WT) mice and Lpa3-/- mice (with delayed implantation) reveals differential expression of several subunits in V0 domain but not those in V1 domain. Realtime PCR and in situ hybridization indicate that both Atp6v0a4 and Atp6v0d2 are expressed at very low levels in the preimplantation uteri. They are significantly up-regulated in WT LE from day 3.5 (pre-implantation) to day 4.5 (post-implantation). Bafilomycin A1 is a V-ATPase inhibitor. Local uterine fat pad injection of bafilomycin A1 (2.5 μg/kg) at 6 pm on day 3.5 delays or prevents embryo implantation in WT mice detected on day 4.5. The suppressed embryo implantation is also confirmed by the sustained progesterone receptor expression in the LE and low level or no expression of amiloride-binding protein 1 (a decidual marker) in the treated uteri at day 4.5. The dynamic temporal expression of Atp6v0a4 and Atp6v0d2 in the LE during peri-implantation and the adverse effect of V-ATPase inhibitor bafliomycin A1 on embryo implantation indicate that the V-ATPase may play an important role in embryo implantation. (Supported by University of Georgia, NIH R15HD066301, and NIH R01HD065939.)