Down-Regulation of Circadian Clock GenePeriod 2in Uterine Endometrial Stromal Cells of Pregnant Rats During Decidualization

Abstract

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.

Hormonal Regulation of Circadian Pacemaker in Ovary and Uterus

“…9). In addition, the circadian rhythm of the Vegf mRNA was consistent with that of the Per2 mRNA (Uchikawa et al, 2011). This suggests a clock regulation of the Vegf gene.…”

“…However, the times of each oscillation in the stroma cells on day 4.50 and day 6.50 of gestation were mostly identical. The expression and distribution of the PER2 protein were investigated by fluorescent immunohistochemistry in different compartments of the uteri (day 4.5) at ZT 4 and ZT12 (Uchikawa et al, 2011). A strong immunostaining signal was detected in the luminal epithelium, as compared to that in the stroma cell layer (Fig.…”

“…The circadian clock system may contribute to the progress of follicular development, luteinization and luteolysis, and steroid hormone-induced proliferation and differentiation of uterine cells through fluctuating hormones. Recently, there is a growing body of evidence that circadian clock genes are expressed in reproductive tissues including the ovary and uterus (Johnson et al, 2005;Nakamura et al, 2005;Fahrenkrug et al, 2006;Dolatshad et al, 2006;Karman & Tischkau, 2006;He et al, 2007aHe et al, , 2007bHe et al, , 2007cNakao et al, 2007;Hirata et al, 2009;Sellix & Menaker, 2010;Uchikawa et al, 2011). Many regulatory elements are located at the upstream of clock genes, such as steroid hormone response element half-sites and the adenosine 3',5'-cyclic monophosphate (cAMP) response element site as well as E-box and D-box elements.…”

Sleep, Circadian Rhythms, and Fertility

“…Clock gene expression has been documented in the uterus [50,78,87,120], oviduct [50,52], and pre-implantation embryo [50]. Therefore, circadian oscillation in the peripheral reproductive organs may play a role in early embryo development and implantation.…”

Contribution of FSH and triiodothyronine to the development of circadian clocks during granulosa cell maturation

“…Primer sets used for qPCR are listed in Table 1. PCR was performed in a 15-l volume containing a 30-ng cDNA sample in Master SYBR Green I mixture (Roche Diagnostics) and 0.5 M specific primers with a Mx3000P Real-Time qPCR System (Stratagene, Santa Clara, CA) using the parameters recommended by the manufacturer (95°C for 10 min, 40 cycles of 95°C for 15 s and 60°C for 1 min, and a dissociation stage of 95°C for 15 s, 60°C for 1 min, and 95°C for 15 s, 60°C for 15 s), as described (13,51). All reactions were performed in triplicate and displayed amplification efficiency between 80 and 120%.…”