A delayed-implantation-associated protein prevents resumption of DNA synthesis by the trophectoderm of delayed-implanting mouse blastocysts in vitro.
Objective of this study was to determine the ability of a delayed-implantation-associated protein (MW 170,000, DIAP170K) to inhibit DNA synthesis by mouse blastocysts. Mice were ovariectomized on day 3 of pregnancy and treated with daily injections with 1 mg progesterone till day 7 to induce delayed implantation. Blastocysts were collected on day 8 with or without a single injection of 25 ng estradiol-17 beta on day 7 that activates blastocyst metabolisms (activated blastocysts and delayed-implanting blastocysts respectively). DNA synthesis was determined by measuring [3H]thymidine incorporation by blastocysts. DIAP170K at 10 micrograms/m/ suppressed resumption of DNA synthesis by delayed-implanting blastocysts and suppression was maximal at 50 micrograms/m/. However, DIAP170K did not affect DNA synthesis by blastocysts obtained on day 5 of pregnancy (normal blastocysts) and activated blastocysts. Resumption of DNA synthesis in the inner cell mass (ICM) and trophectoderm from delayed-implanting blastocysts was then separately assessed. DNA synthesis resumed in the trophectoderm of intact blastocysts during 24-hr culture but not in the trophectoderm cultured apart from the ICM. DIAP170K inhibited the resumption of DNA synthesis by the trophectoderm of intact delayed-implanting blastocysts but did not affect DNA synthesis by the ICM. In conclusion, DIAP170K inhibits resumption of DNA synthesis by trophectoderm of delayed-implanting blastocysts. This action of DIAP170K may play a central role in maintaining, but not achieving, dormancy of DNA synthesis by delayed-implanting blastocysts in mice.
Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
S
S
Katagiri
Y
Y
Takahashi
H
H
Kanagawa
B H
BH
Yuen
Y S
YS
Moon
D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D004247:DNA / Q000096:biosynthesis*; D004475:Ectoderm / Q000502:physiology*; D010064:Embryo Implantation / Q000187:drug effects / Q000502:physiology*; D010065:Embryo Implantation, Delayed / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005865:Gestational Age; D006023:Glycoproteins / Q000502:physiology*; D051379:Mice; D010052:Ovariectomy; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology / Q000502:physiology*; D014327:Trophoblasts / Q000166:cytology / Q000502:physiology*
D006023:Glycoproteins; D011374:Progesterone; D004958:Estradiol; D004247:DNA