title: Insulin-like growth factor I induces proliferation and migration of porcine trophectoderm cells through multiple cell signaling pathways, including protooncogenic protein kinase 1 and mitogen-activated protein kinase.
abstract: During early pregnancy, the developing conceptus is dependent upon a wide range of growth factors and nutrients that are secreted by or transported by uterine epithelia into the uterus at the maternal-conceptus interface for successful implantation and placentation. Among these factors, insulin-like growth factor-I (IGF-I) is known to play an important role in development of the early embryo and uterine endometrium. However, few studies have been conducted with pigs to determine IGF-I-induced functional effects on peri-implantation embryos such as activation of cell signaling cascades responsible for growth, proliferation and differentiation of cells of the conceptus. Therefore, the aim of this study was to analyze mRNA expression of endometrial IGF-I and its receptor, to examine the functional role of IGF-I on primary porcine trophectoderm (pTr) cells and to assess potential signaling pathways responsible for biological activities of IGF-1. In the present study, expression of endometrial type I IGF receptor (IGF-IR) mRNA increased significantly from Day 10 to Day 12 of pregnancy and the increase was greater for pregnant than cyclic gilts. Both IGF-I and IGF-IR mRNAs were abundant in endometrial luminal-, glandular epithelia, and stratum compactum stroma on Day 12 of pregnancy. In addition, IGF-I significantly induced phosphorylation of AKT1, ERK1/2 and RPS6 in a time- and concentration-dependent manner in pTr cells. Immunofluorescence microscopy revealed that IGF-I treated pTr cells exhibited increased abundance of phosphorylated (p)-AKT1 and p-ERK1/2 MAPK proteins in the nucleus and cytoplasm, and p-RPS6 proteins in the cytosol as compared to non-treated pTr cells. In the presence of the ERK1/2 MAPK inhibitor (U0126), IGF-I-induced AKT1 phosphorylation was not affected, whereas the PI3K inhibitor (LY294002) decreased IGF-I-induced phosphorylation of ERK1/2 and AKT1 proteins, and both the PI3K-AKT1 and ERK1/2 MAPK pathways were blocked by LY294002. Furthermore, IGF-I significantly stimulated both proliferation and migration of pTr cells, but these effects were blocked by P38 inhibitor (SB203580), U0126, MTOR inhibitor (rapamycin) and LY294002. Taken together, these results indicate that IGF-I coordinately regulates multiple cell signaling pathways including PI3K-AKT1-RPS6 and ERK1/2 MAPK signaling pathways that are critical to proliferation, migration and survival of trophectoderm cells during early pregnancy in pigs.
authors: Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.
authors: Wooyoung
authors: W
authors: Jeong
authors: Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.
authors: Gwonhwa
authors: G
authors: Song
authors: Center for Animal Biotechnology and Genomics and Department of Animal Science, Texas A&M University, College Station, TX, USA.
authors: Fuller W
authors: FW
authors: Bazer
authors: Department of Animal Resources Science, Dankook University, Cheonan, Republic of Korea. Electronic address: jinyoungkim@dankook.ac.kr.
authors: Jinyoung
authors: J
authors: Kim
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004475:Ectoderm / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D007093:Imidazoles / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011247:Pregnancy; D061251:Primary Cell Culture; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002070:Butadienes; D002867:Chromones; D007093:Imidazoles; D007334:Insulin-Like Growth Factor I; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D009570:Nitriles; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011725:Pyridines; D012333:RNA, Messenger; D017526:Receptor, IGF Type 1; D038601:Ribosomal Protein S6; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580
keywords: Insulin-like growth factor; Migration; Pig; Proliferation; Trophoblast