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The peripheral circadian oscillator plays an essential role in synchronizing local physiology to operate in a circadian manner via regulation of the expression of clock-controlled genes. The present study aimed to evaluate the circadian rhythms of clock genes and clock-controlled genes expressed in the rat uterus endometrial stromal cells (UESCs) during the stage of implantation by a DNA microarray. Of 12,252 genes showing significantly expression, 7,235 genes displayed significant alterations. As revealed by the biological pathway analysis using the database for annotation, visualization, and integrated discovery online annotation software, genes were involved in cell cycle, glutathione metabolism, MAPK signaling pathway, fatty acid metabolism, ubiquitin mediated proteolysis, focal adhesion, and PPAR signaling pathway. The clustering of clock genes were mainly divided into four groups: the first group was Rorα,Timeless, Npas2, Bmal1, Id2, and Cry2; the second group Per1, Per2, Per3, Dec1, Tef, and Dbp; the third group Bmal2, Cry1, E4bp4, Rorβ, and Clock; the fourth group Rev-erbα. Eleven implantation-related genes and 24 placenta formation-related genes displayed significant alterations, suggesting that these genes involved in implantation and placenta formation are controlled under circadian clock. Some candidates as clock-controlled genes were evaluated by using RNA interference to Bmal1 mRNA. Down-regulation of Igf1 gene expression was observed by Bmal1 silencing, whereas the expression of Inhβa was significantly increased. During active oscillation of circadian clock, the apoptosis-related genes Fas and Caspase3 remained no significant changes, but they were significantly increased by knockdown of Bmal1 mRNA. These results indicate that clock-controlled genes are up-or down-regulated in rat UESCs during the stage of decidualization. DNA microarray analysis coupled with RNA interference will be helpful to understand the physiological roles of some oscillating genes in blastocyst implantation and placenta formation. [ABSTRACT FROM AUTHOR]

Circadian rhythms are modulated in a variety of peripheral tissues, including in the uterus where endometrial stromal cells (UESCs) undergo proliferation and differentiation (decidualization) during gestation. Here the authors focused on circadian rhythms in UESCs during implantation and decidualization in rodents. As revealed by analyses of cultured UESCs from pregnant Per2 promoter- dLuc transgenic rats, Per2 oscillation of ∼24 h was observed in response to dexamethasone. Per2 oscillation was enhanced in UESCs during implantation, whereas they were attenuated during decidualization. In vivo studies showed that PER2 protein in the uteri displayed a peak at zeitberger time 4 (ZT 4) (day 4.50 of gestation) and a trough at ZT 12 (day 4.83), indicating its circadian rhythmicity. Conversely, no significant circadian rhythm of the PER2 protein was observed during decidualization. Fluorescent immunohistochemical studies also supported circadian rhythmicity of the PER2 protein in its intracellular distribution. In accordance with Per2 mRNA expression, a circadian rhythm of vascular endothelial growth factor ( Vegf) gene expression, having several E-box or E-box-like sites at the upstream of the transcription start site, was observed during implantation, showing a peak at ZT 0 and a trough at ZT 12. In contrast, Vegf mRNA expression displayed no circadian rhythm during decidualization. Collectively, the present results prove that Per2 oscillation is down-regulated in UESCs during decidualization. It is strongly suggested that cellular differentiation in UESCs interferes with circadian clockwork. (Author correspondence: ) [ABSTRACT FROM AUTHOR]

Interferon tau (IFNT) is thought to have essential functions in maternal recognition and establishment of pregnancy in ruminants. There, however, is a lack of research on embryonic factors that affect pregnancy other than IFNT. The present study was conducted to determine what are other embryo-derived factors involved in pregnancy recognition and to identify effects on endometrial cells using an in vitro culture system. With use of LC–MS/MS procedures to evaluate the supernatant of elongating embryos of cattle in culture, there was detection of 78 secretary proteins including five cytokines and two growth factors. Then there was analysis for up-regulated genes using ingenuity pathway procedure, IFNT and MIF were identified as upstream regulators of 37 and five genes, respectively. The mRNA transcript of MIF receptors was identified in endometrial cells, however, not in embryos. Among genes induced by MIF, CCL2, IL7 and IL23A transcripts were identified in endometrial cells. When endometrial cells were treated with interferon alpha (IFNA) and MIF, the CCL2 transcript was in a larger abundance of endometrial epithelial and polymorphonuclear neutrophil cells, and there was a larger abundance of there mRNA transcripts as a result of MIF treatment of peripheral blood mononuclear cells. In conclusion, MIF secreted by elongating embryos of cattle synergistically regulates relative abundances of specific mRNA transcripts of endometrial cells when there is treatment with IFNA, indicating further there are several factors other than IFNT that have effects on gene expression in the endometrium during early stages of gestation in cattle. [ABSTRACT FROM AUTHOR]