UBC Theses and Dissertations
Characterization of cadherins, adamts, steroid receptors, during blastocyst formation in vitro of adamts in the bovine ovary Madan, Pavneesh
In bovine, early embryonic mortality (EEM) results in low reproductive efficiency, the major cause for which is believed to be impaired development of the embryo, but mechanisms involved therein remain poorly understood. A lack of progesterone support from the corpus luteum (CL) also contributes to EEM. Recent studies demonstrate that regulated expression of distinct cadherins that mediate Ca²⁺ - dependent cell-cell adhesion and ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) subtypes involved in cell-matrix interactions, and steroid receptors mediate important cellular events underlying the formation and organization of tissues, however, their role in preimplantation embryogenesis is poorly characterized. Understanding genes involved in the blastocyst and CL formation provides interesting possibilities in improving embryo viability. To address these issues, investigations into the expression of cadherins, ADAMTS, estrogen and progesterone receptor isoforms during the preimplantation embryogenesis in bovine embryos at timed stages of development has been undertaken, using reverse transcription-polymerase chain reaction (RT-PCR) or immunohistochemistry strategies. In addition, expression of ADAMTS subtypes in ovarian follicles and CL has also been characterized. These studies indicate that multiple cadherins, both type 1 (E-, N - and P-Cad) and type 2 (cad-8, -10 and -11), with their specific localizations, at least in part, provide the molecular basis for the formation and organization of the inner cell mass and the trophectoderm. The differential mRNA and protein expression of steroid receptor isoforms (ERα, ERβ, PRA and PRB) suggests distinct role(s) during early embryogenesis and provides evidence for direct effect of steroids on the embryo. The regulated but complex expression of ADAMTS subtypes both in the embryo (ADAMTS-1, -4, -5, -6, -8, -9, -10, but not ADAMTS-2, -3, -7 or -12) and the ovary (ADAMTS-1, -2, -3, -4, -5, -7, -8, -9, but not ADAMTS-6, -10 or -12) suggests that these proteinases could be involved in cell-matrix interactions and contributing towards important cellular events like cell migration, differentiation and remodeling of the extracellular matrix. Though, the biological significance of these molecules remains unclear, these studies demonstrate that novel cellular molecules involved in cell-cell, cell-matrix and steroid interactions could be playing a key role during developmental processes like embryogenesis and/or CL formation.
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