title: Proteins in the extraembryonic matrix of preimplantation rabbit embryos.
abstract: Preimplantation embryos of several species are surrounded by an extraembryonic matrix (often simply named zona pellucida) until briefly before implantation. All signals of the early embryo-maternal dialogue have to pass this matrix and therefore are detectable inside. We investigated the protein pattern of the extraembryonic matrices of 3-6-day-old rabbit embryos by two-dimensional gel-electrophoresis. Using (35)S-methionine incorporation, embryonic proteins were labelled and could be distinguished from maternal proteins. Furthermore, the presence of three different proteins (insulin-like growth factor-binding protein-3, uteroglobin, haptoglobin) within the matrices of day-6 embryos was investigated by Western blot analysis. The pattern and numbers of protein spots detected was clearly dependent on the time of embryonic development. Of all proteins detected, 19.3% and 33% are of embryonic origin (day 5 and day 6, respectively). At day 4 the zona proteins are no longer detectable, reflecting the degradation of the zona pellucida. From day 4 to day 5 proteins detectable within the extraembryonic matrices increase enormously. This demonstrates that embryo-maternal signalling accelerates at least 2 days before implantation. Insulin-like growth factor-binding protein-3, uteroglobin and haptoglobin are part of the early signalling as shown by Western blot analysis. Insulin-like growth factor-binding protein-3 could be detected as one spot at 38 kDa pI 6.1, uteroglobin at 8 kDa pI 6.0 and haptoglobin as two spots/isoforms at 36/38 kDa pI 5.8 and pI 6.0. These results demonstrate that extraembryonic matrices serving as a mailbox are a valuable tool for investigating early embryo-maternal signalling.
authors.affiliation: Department of Anatomy and Reproductive Biology, Medical School, RWTH University of Aachen, Wendlingweg 2, 52057 Aachen, German. aherrler@ukaachen.de
authors.forename: A
authors.initials: A
authors.lastname: Herrler
authors.forename: M
authors.initials: M
authors.lastname: von Wolff
authors.forename: H M
authors.initials: HM
authors.lastname: Beier
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006242:Haptoglobins / Q000378:metabolism; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism*; D011817:Rabbits; D015398:Signal Transduction; D014598:Uteroglobin / Q000378:metabolism; D015044:Zona Pellucida / Q000378:metabolism*
chemical_list: D006242:Haptoglobins; D018972:Insulin-Like Growth Factor Binding Protein 3; D011506:Proteins; D014598:Uteroglobin