Résumé
Calmodulin-dependent protein kinase (CaMK), activated by auto-phosphorylation at the presence of calcium and calmodulin, is widely distributed in eukaryotes. CaMKs are important mediators of calcium signal in eukaryotes. Recent researches have suggested that CaMKⅡ is involved in the regulation of meiotic cell cycle of oocytes. It plays functional roles in meiotic maturation, polar body extrusion, fertilization and egg activation. As one of the down-stream signaling molecules of calcium, CaMKⅡ facilitates the inactivation of maturation promoting factor (MPF) and cytostatic factor (CSF) following fertilization, as well as the spindle microtubule organization and centrosome duplication. Although the functions of CaMKⅡ in oocyte meiosis are versatile and essential, the present results are primarily obtained from low vertebrates and mouse. In future studies, the function and regulation of this kinase in other mammals should be stressed.
Résumé
Implantation window is the transient period when the embryos develop into blastocysts and the uterus differentiates into the receptive state synchronically. Estrogen and progesterone are the comprehensive regulating molecules during this process. They influence the proliferation and differentiation of multiple cell types in the uterus through the modulation of various local-signaling molecules.Uterus and blastocyst interact by the paracrine effects of prostaglandin, histamine, calcitonin, cytokines and growth factors at implantation window. This molecular cross-talk modulates the interaction between trophectoderm and uterine luminal epithelium. Once the implantation window is open, it then switches into unreceptive state spontaneously.