title: Dual source and target of heparin-binding EGF-like growth factor during the onset of implantation in the hamster.
abstract: Heparin binding EGF-like growth factor (HB-EGF), encoded by the Hegfl gene, is considered as an important mediator of embryo-uterine interactions during implantation in mice. However, it is unknown whether HB-EGF is important for implantation in species with different steroid hormonal requirements. In mice and rats, maternal ovarian estrogen and progesterone (P(4)) are essential to implantation. In contrast, blastocyst implantation can occur in hamsters in the presence of P(4) alone. To ascertain whether HB-EGF plays any role in implantation in hamsters, we examined the expression, regulation and signaling of HB-EGF in the hamster embryo and uterus during the periimplantation period. We demonstrate that both the blastocyst and uterus express HB-EGF during implantation. Hegfl is expressed solely in the uterine luminal epithelium surrounding the blastocyst prior to and during the initiation of implantation. Hypophysectomized P(4)-treated pregnant hamsters also showed a similar pattern of implantation-specific Hegfl expression. These results suggest that uterine Hegfl expression at the implantation site is driven by either signals emanating from the blastocyst or maternal P(4), but not by maternal estrogen. However, in ovariectomized hamsters, uterine induction of Hegfl requires the presence of estrogen and activation of its nuclear receptor (ER), but not P(4). This observation suggests an intriguing possibility that an estrogenic or unidentified signal from the blastocyst is the trigger for uterine HB-EGF expression. An auto-induction of Hegfl in the uterus by blastocyst-derived HB-EGF is also a possibility. We further observed that HB-EGF induces autophosphorylation of ErbB1 and ErbB4 in the uterus and blastocyst. Taken together, we propose that HB-EGF production and signaling by the blastocyst and uterus orchestrate the 'two-way' molecular signaling to initiate the process of implantation in hamsters.
authors.affiliation: Department of Pediatrics, Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City 66160-7338, USA.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.forename: Haibin
authors.initials: H
authors.lastname: Wang
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Shyamal K
authors.initials: SK
authors.lastname: Roy
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Das
authors.forename: Bibhash C
authors.initials: BC
authors.lastname: Paria
mesh_terms: D000818:Animals; D006224:Cricetinae; D010064:Embryo Implantation / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000235:genetics / Q000502:physiology*; D066246:ErbB Receptors / Q000502:physiology; D005260:Female; D066257:Heparin-binding EGF-like Growth Factor; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D066247:Receptor, ErbB-4; D014599:Uterus / Q000502:physiology
chemical_list: C587884:Hbegf protein, mouse; C587885:Hbegf protein, rat; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D004815:Epidermal Growth Factor; D010770:Phosphotransferases; D066246:ErbB Receptors; C587690:Erbb4 protein, mouse; C587691:Erbb4 protein, rat; D066247:Receptor, ErbB-4