Muc-1, integrin, and osteopontin expression during the implantation cascade in sheep

Center for Animal Biotechnology and Genomics, Texas A&M University, College Station, TX 77843-2471, USA.
Biology of Reproduction (Impact Factor: 3.32). 10/2001; 65(3):820-8.
Source: PubMed


The extracellular matrix protein osteopontin (OPN) is a component of histotroph that increases in uterine flushings from pregnant ewes during the peri-implantation period and is localized on the apical surfaces of the uterine luminal epithelium (LE) and conceptus trophectoderm (Tr). The potential involvement of OPN in the implantation adhesion cascade in sheep was investigated by examining temporal, spatial, and potential functional relationships between OPN, Muc-1, and integrin subunits during the estrous cycle and early pregnancy. Immunoreactive Muc-1 was highly expressed at the apical surfaces of uterine luminal (LE) and glandular epithelium (GE) in both cycling and pregnant ewes but was decreased dramatically on LE by Day 9 and was nearly undetectable by Day 17 of pregnancy when intimate contact between LE and Tr begins. In contrast, integrin subunits αν, α4, α5, β1, β3, and β5 were constitutively expressed on conceptus Tr and at the apical surface of uterine LE and GE in both cyclic and early pregnant ewes. The apical expression of these subunits could contribute to the apical assembly of several OPN receptors including the ανβ3, ανβ1, α4β1, and α5β1 heterodimers on endometrial LE and GE, and conceptus Tr in sheep. Functional analysis of potential OPN interactions with conceptus and endometrial integrins was performed on LE and Tr cells in vitro using beads coated with OPN, poly-L-lysine, or recombinant OPN in which the Arg-Gly-Asp sequence was replaced with RGE or RAD. Transmembrane accumulation of talin or α-actinin at the apical surface of uterine LE and conceptus Tr cells in contact with OPN-coated beads revealed functional integrin activation and cytoskeletal reorganization in response to OPN binding. These results provide a physiological framework for the role of OPN, a potential mediator of implantation in sheep, as a bridge between integrin heterodimers expressed by Tr and uterine LE responsible for adhesion for initial conceptus attachment.

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    • "Osteopontin gene in buffalo encodes a protein of 280 amino acids and has insertion of two amino acids at positions 94 (Aspartic acid) and 227 (Asparagine), thus making a total of 280 amino acids as compared to 278 amino acids in bovines and ovines (Tantia et al. 2008). Multiple integrin receptors for OPN are present on trophoblasts and LE of humans and domestic animals, some of which increase during the peri-implantation period (Johnson et al. 2001). Evidence suggests that secreted OPN binds integrin receptors expressed on conceptus trophoblast and endometrial LE, where it can stimulate changes in proliferation, migration, survival, adhesion and remodeling of the conceptus as it elongates, apposes and adheres to the LE. "
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    ABSTRACT: Early embryonic mortality is one of the main sources of reproductive wastages and major constraints for full exploitation of the production potential of livestock. The survivality of embryo during early embryonic life is mostly dependent on the efficiency with which the maternal recognition of pregnancy (MRP) is established. Maternal recognition of pregnancy involves molecular dialogue between the trophoblast of conceptus and uterine endometrium. Embryonic development to the blastocyst stage and uterine differentiation to the receptive environment are crucial for successful establishment of the embryo-uterine cross-talk that leads to the initiation and progression of successful implantation. Unravelling the complex intricate molecular and cellular dialogues between the conceptus and uterine environment will facilitate development of strategies to augment early embryo survivality.
    Full-text · Article · Dec 2015
    • "Placenta detailed information is available on the complex interplay of integrin subunits, Muc-1 and mediating matrix molecules like osteopontin (OPN) [3]. Molecules serving as potential inducers of such depolarization could be trophoblast products like pregnancy associated glycoproteins (PAG) [4] or IFN-tau, which is produced by uninucleate trophoblast in enlarging blastocysts and is believed to act as the maternal recognition signal in ruminants [5]. "
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    ABSTRACT: The feto-maternal interface during bovine implantation was studied in vivo and using three-dimensional bovine endometrial (BCECph) and trophoblast spheroids (CCS), each with underlying fibroblasts. The expression of ezrin and cytokeratin 18 (CK18) was analyzed via immunohistochemistry (IHC), RT-PCR and western blotting in bovine endometrium (GD 18-44) with in vivo (VIVO) and in vitro-produced embryos (VITRO). BCECph were stimulated with cotyledon-conditioned media (CCM) and analyzed by TEM/SEM and IHC. CCS were stained (IHC) for TGC markers, to test if spheroidal trophoblast cells had differentiated into TGC. At GD 20, caruncular epithelium (CE) and uterine glands (UG) showed a loss of cytosolic ezrin and CK18 followed by a complete loss of both proteins. At GD 35 both reappeared in CE and UG. The endometrial expression pattern did not differ between VIVO and VITRO. RT-PCR and western blotting confirmed the presence of ezrin and CK18. All spheroids had an outer polarized, cytokeratin and ezrin positive epithelium (CE or trophoblast) with apical microvilli. Stimulation of BCECph with CCM induced similar changes in ezrin expression as observed in endometrial tissue. However, no ultrastructural alterations were found by transmission electron microscopy. Absence of TGC-specific glycoproteins in CCS indicated that TGC differentiation was not induced by three-dimensional culture conditions. Ezrin and CK18 are downregulated during implantation in cattle. The expression changes represent a temporal depolarization, which could be important for an establishment of bovine pregnancy. Our in vitro experiments demonstrate that the trophoblast could contribute to this change in vivo. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Jun 2015 · Placenta
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    • " disrupters block or modify uterine adenogenesis ; therefore , stromal cell - derived growth factors may exert effects only on uterine LE which is insufficient in its produc - tion of components of histotroph required for conceptus development . Down - regulation of PGR correlates with loss of MUC1 on uterine LE that interferes with implantation ( Johnson et al . , 2001 ) . Further , silencing expression of PGR in ovine uterine epithelia allows P4 to act via PGR - positive uterine stromal cells to induce Fig . 4 . Down - regulation of receptors for progesterone ( PGR ) is a common feature of pregnancy in mammals . It is required for down - regulation of expression of mucin 1 ( Muc - 1 ) which would oth"
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