Integrins and extracellular matrix proteins at the maternal-fetal interface in domestic animals.
ABSTRACT Establishment of pregnancy in mammals requires coordinated conceptus-maternal interactions involving numerous hormones, growth factors and cytokines acting via specific receptors in the uterus. Uterine secretions play an important role in establishing synchrony between development of the conceptus and uterine receptivity, as well as in conceptus remodeling, adhesion, implantation and placentation in domestic species. Studies of non-invasive implantation in domestic livestock provide valuable opportunities to investigate fundamental processes of the initial events of apposition, attachment and adhesive interactions that are shared among species. In pigs and sheep, it appears that integrins play a dominant role in these fundamental processes via interactions with extracellular matrix molecules and other ligands to transduce cellular signals in uterine epithelial cells and conceptus trophectoderm. This review considers several of the potential integrin-binding ligands involved in the complex implantation adhesion cascade in pigs and sheep along with in vitro evidence for the transduction of cytoplasmic signals that may be required to sustain fetal and maternal contributions to the formation of the epitheliochorial placenta.
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ABSTRACT: The pig exhibits true epitheliochorial placentation, where the fetal membrane maintains attachment throughout pregnancy but does not invade into the maternal uterine endometrium. Accordingly, the expression and function of cell adhesion molecules are very important for embryo implantation and the establishment of pregnancy. In our recent microarray analysis, we found that activated leukocyte cell adhesion molecule (ALCAM) was expressed in the uterine endometrium during pregnancy in pigs. To better understand the roles of ALCAM in the establishment and maintenance of pregnancy, we examined ALCAM expression in the uterine endometrium during the estrous cycle and pregnancy in pigs. Real-time RT-PCR analysis showed that ALCAM was differentially expressed in the uterine endometrium during the estrous cycle and pregnancy, with the highest levels on D12 of pregnancy. ALCAM mRNA was localized to the luminal and glandular epithelial cells and to the trophectoderm of conceptuses during early pregnancy. The steroid hormones estrogen and progesterone had no effect on ALCAM expression in an endometrial explant culture study. Further, we found that ALCAM expression in the uterine endometrium from gilts with somatic cell nuclear transfer-derived embryos was not different from that in gilts with embryos from natural mating. ALCAM was expressed in a pregnancy stage- and cell type-specific manner in the uterine endometrium and conceptuses during pregnancy. These findings suggest that ALCAM may play a role in the establishment of pregnancy. Further analysis of ALCAM will provide insight into the implantation process and establishment of pregnancy in pigs.Asian Australasian Journal of Animal Sciences 07/2011; 24(7). · 0.56 Impact Factor
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ABSTRACT: Establishment of pregnancy in pigs involves maintaining progesterone secretion from the corpora lutea in addition to regulating a sensitive interplay between the maternal immune system and attachment of the rapidly expanding trophoblast for nutrient absorption. The peri-implantation period of rapid trophoblastic elongation followed by attachment to the maternal uterine endometrium is critical for establishing a sufficient placental-uterine interface for subsequent nutrient transport for fetal survival to term, but is also marked by the required conceptus release of factors involved with stimulating uterine secretion of histotroph and modulation of the maternal immune system. Many endometrial genes activated by the conceptus secretory factors stimulate a tightly controlled proinflammatory response within the uterus. A number of the cytokines released by the elongating conceptuses stimulate inducible transcription factors such as nuclear factor kappa B (NFKB) potentially regulating the maternal uterine proinflammatory and immune response. This review will establish the current knowledge for the role of conceptus cytokine production and release in early development and establishment of pregnancy in the pig.Journal of animal science and biotechnology. 01/2014; 5(1):51.
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ABSTRACT: Pregnancy requires successful implantation of an embryo, which occurs during a restricted period defined as 'receptivity of the endometrium' and is influenced by the ovarian steroids progesterone and oestradiol. The role of poly(ADP-ribose) polymerase-1 (PARP-1) in apoptosis is well established. However, it is also involved in cell differentiation, proliferation and tissue remodelling. Previous studies have described the presence of poly(ADP-ribose)polymerase (PARP) in the uterus, but its exact role in embryo implantation is not yet elucidated. Hence, we studied the expression of PARP-1 in the uterus during embryo implantation and decidualization, and its regulation by ovarian steroids. Our results show upregulation of the native form of PARP-1 (~116kDa) in the cytosolic and nuclear compartments of implantation and non-implantation sites at day5 (0500 h), followed by downregulation at day5 (1000 h), during the embryo implantation period. The transcript level of Parp-1 was also augmented during day5 (0500 h). Inhibition of PARP-1 activity by the drug EB-47 decreased the number of embryo implantation sites and blastocysts at day5 (1000 h). Further, cleavage of native PARP-1 was due to the activity of caspase-3 during the peri-implantation stage [day5 (0500 h)], and is also required for embryo implantation, as inhibition of its activity compromised blastocyst implantation. The native (~116kDa) and cleaved (~89kDa) forms of PARP-1 were both elevated during decidualization of the uterus. Furthermore, the expression level of PARP-1 in the uterus was found to be under the control of the hormone oestrogen. Our results clearly demonstrate that PARP-1 participates in the process of embryo implantation.Reproduction 02/2014; · 3.26 Impact Factor