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  • Author: Yan Yang x
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Haolin Zhang, Ming Yi, Yan Zhang, Hongyan Jin, Wenxin Zhang, Jingjing Yang, Liying Yan, Rong Li, Yue Zhao and Jie Qiao

Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder with unclear etiology and unsatisfactory management. Effects of diets on the phenotype of PCOS were not fully understood. In the present study, we applied 45 and 60% high-fat diets (HFDs) on a rat model of PCOS induced by postnatal DHEA injection. We found that both DHEA and DHEA+HFDs rats exhibited reproductive abnormalities, including hyperandrogenism, irregular cycles and polycystic ovaries. The addition of HFDs, especially 60% HFDs, exaggerated morphological changes of ovaries and a number of metabolic changes, including increased body weight and body fat content, impaired glucose tolerance and increased serum insulin levels. Results from qPCR showed that DHEA-induced increased expression of hypothalamic androgen receptor and LH receptor were reversed by the addition of 60% HFDs. In contrast, the ovarian expression of LH receptor and insulin receptor mRNA was upregulated only with the addition of 60% HFDs. These findings indicated that DHEA and DHEA+HFDs might influence PCOS phenotypes through distinct mechanisms: DHEA affects the normal function of hypothalamus–pituitary–ovarian axis through LH, whereas the addition of HFDs exaggerated endocrine and metabolic dysfunction through ovarian responses to insulin-related mechanisms. We concluded that the addition of HFDs yielded distinct phenotypes of DHEA-induced PCOS and could be used for studies on both reproductive and metabolic features of the syndrome.

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Shuai Lin, Yu-Yuan Zhu, Wei Hu, Yan Yang, Jia-Mei Luo, Shijun Hu and Zeng-Ming Yang

Decidualization is required for the successful establishment of pregnancy in rodents and primates. Fatty acid desaturase 3 (Fads3) belongs to the fatty acid desaturase family, which is a crucial enzymes for highly unsaturated fatty acid biosynthesis. However, the expression, regulation and function of Fads3 during early pregnancy in mice are still unknown. In this study, we examined Fads3 expression, regulation and function during mouse decidualization. The expression of Fads3 is detected in the subluminal stromal cells at implantation site on day 5 of pregnancy, but not at inter-implantation site and in day 5 pseudopregnant uteri. Compared to delayed implantation, Fads3 is strongly expressed after delayed implantation is activated by estrogen treatment. From days 6 to 8, Fads3 mRNA signals are significantly detected in the decidua. In ovariectomized mice, estrogen significantly stimulates Fads3 expression. However, estrogen has no effect on Fads3 expression in ovariectomized ERα deficient mice, suggesting that estrogen regulation on Fads3 expression is ERα-dependent. When ovariectomized mice were treated with progesterone, Fads3 expression is significantly increased by progesterone. Progesterone stimulation on Fads3 expression is also detected in cultured stromal cells, which is abrogated by RU486 treatment. These data indicate that progesterone upregulation on Fads3 expression is progesterone receptor-dependent. Fads3 knockdown by siRNA reduces in vitro decidualization of mouse stromal cells. Taken together, Fads3 may play an important role during mouse decidualization.

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Jing Cong, Hong-Lu Diao, Yue-Chao Zhao, Hua Ni, Yun-Qin Yan and Zeng-Ming Yang

It has been shown that both prostaglandin I2 (PGI2) and PGE2 are essential for mouse implantation, whereas only PGE2 is required for hamster implantation. To date, the expression and regulation of cyclooxygenase (COX) and prostaglandin E synthase (PGES), which are responsible for PGE2 production, have not been reported in the rat. The aim of this study was to examine the expression pattern and regulation of COX-1, COX-2, membrane-associated PGES-1 (mPGES-1), mPGES-2 and cytosolic PGES (cPGES) in rat uterus during early pregnancy and pseudopregnancy, and under delayed implantation. At implantation site on day 6 of pregnancy, COX-1 immunostaining was highly visible in the luminal epithelium, and COX-2 immunostaining was clearly observed in the subluminal stroma. Both mPGES-1 mRNA and protein were only observed in the subluminal stroma surrounding the implanting blastocyst at the implantation site on day 6 of pregancy , but were not seen in the inter-implantation site on day 6 of pregnancy and on day 6 of pseudopregnancy. Our data suggest that the presence of an active blastocyst is required for mPGES-1 expression at the implantation site. When pregnant rats on day 5 were treated with nimesulide for 24 h, mPGES-1 protein expression was completely inhibited. cPGES immunostaining was clearly observed in the luminal epithelium and subluminal stromal cells immediately surrounding the implanting blastocyst on day 6 of pregnancy. mPGES-2 immunostaining was clearly seen in the luminal epithelium at the implantation site. Additionally, immunostaining for prostaglandin I synthase (PGIS) was also strongly detected at the implantation site. In conclusion, our results indicate that PGE2 and PGI2 should have a very important role in rat implantation.

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Xiaokui Yang, Ying Zhou, Sha Peng, Liang Wu, Hai-Yan Lin, Shuyu Wang and Hongmei Wang

Recent studies implicate the regulatory function of microRNAs (miRNAs) in oocyte maturation and ovarian follicular development. Differentially expressed miRNAs are found in the plasma of premature ovarian failure (POF) patients and normal cycling women. In this study, miRNA-regulated signaling pathways and related genes were described using Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis. The effect of mir-23a on granulosa cell apoptosis was also studied by examining the protein expression of X-linked inhibitor of apoptosis protein (XIAP) and caspase-3, followed by subsequent counting of apoptotic cells after Hoechst 33258 staining. Both GO analysis and pathway analysis suggested that many signaling pathways, including the AKT signaling pathway, steroid hormone receptor signaling pathways, and others, were regulated by this group of differentially expressed miRNAs. A decrease in XIAP expression (mRNA and protein level) and caspase-3 protein levels and an increase in cleaved caspase-3 protein were observed in human ovarian granulosa cells transfected with pre-mir-23a, along with an increased occurrence of apoptosis. In conclusion, differentially expressed miRNAs in the plasma of POF patients may have regulatory effects on proliferation and apoptosis of granulosa cells by affecting different signaling pathways. Mir-23a may play important roles in regulating apoptosis via decreasing XIAP expression in human ovarian granulosa cells.

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Xiaohui Cui, Yan Sun, Xiuge Wang, Chunhong Yang, Zhihua Ju, Qiang Jiang, Yan Zhang, Jinming Huang, Jifeng Zhong, Miao Yin and Changfa Wang

The micromolar calcium-activated neutral protease gene (CAPN1) is a physiological candidate gene for sperm motility. However, the molecular mechanisms involved in regulating the expression of the CAPN1 gene in bulls remain unknown. In this study, we investigated the expression pattern of CAPN1 in testis, epididymis, and sperm at the RNA and protein levels by qRT-PCR, western blot, immunohistochemistry, and immunofluorescence assay. Results revealed that the expression of CAPN1 levels was higher in the sperm head compared with that in other tissues. Moreover, we identified a novel single-nucleotide polymorphism (g.-1256 A>C, ss 1917715340) in the noncanonical core promoter of the CAPN1 gene between base g.-1306 and g.-1012. Additionally, we observed greater sperm motility in bulls with the genotype CC than in those with the genotype AA (P<0.01), indicating that different genotypes were associated with the bovine semen trait. Furthermore, a higher fluorescence intensity of the C allele than that of the A allele at g. -1256 A>C was revealed by transient transfection in MLTC-1 cells and luciferase report assay. Finally, CAPN1 was highly expressed in the spermatozoa with the CC genotype compared with that with the AA genotype by qRT-PCR. This study is the first report on genetic variant g.-1256 A>C in the promoter region of CAPN1 gene association with the semen quality of Chinese Holstein bulls by influencing its expression. g.-1256 A>C can be a functional molecular marker in cattle breeding.

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Xiao-Qian Meng, Ke-Gang Zheng, Yong Yang, Man-Xi Jiang, Yan-Ling Zhang, Qing-Yuan Sun and Yun-Long Li

Microfilaments (actin filaments) regulate various dynamic events during meiotic maturation. Relatively, little is known about the regulation of microfilament organization in mammalian oocytes. Proline-rich tyrosine kinase2 (Pyk2), a protein tyrosine kinase related to focal adhesion kinase (FAK) is essential in actin filaments organization. The present study was to examine the expression and localization of Pyk2, and in particular, its function during rat oocyte maturation. For the first time, by using Western blot and confocal laser scanning microscopy, we detected the expression of Pyk2 in rat oocytes and found that Pyk2 and Try402 phospho-Pyk2 were localized uniformly at the cell cortex and surrounded the germinal vesicle (GV) or the condensed chromosomes at the GV stage or after GV breakdown. At the metaphase and the beginning of anaphase, Pyk2 distributed asymmetrically both in the ooplasm and the cortex with a marked staining associated with the chromosomes and the region overlying the meiotic spindle. At telophase, Pyk2 was observed in the cleavage furrows in addition to its cortex and cytoplasm localization. The dynamics of Pyk2 were similar to that of F-actin, and this kinase was found to co-localize with microfilaments in several developmental stages during rat oocyte maturation. Microinjection of Pyk2 antibody demolished the microfilaments assembly and also inhibited the first polar body (PB1) emission. These findings suggest an important role of Pyk2 for rat oocyte maturation by regulating the organization of actin filaments.

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Zechen Yan, Dandan Fan, Qingjun Meng, Jinjian Yang, Wei Zhao, Fei Guo, Dongjian Song, Ruiming Guo, Ke Sun and Jiaxiang Wang

The production of haploid gametes by meiosis is a cornerstone of sexual reproduction and maintenance of genome integrity. Zfp38 mRNA is expressed in spermatocytes, indicating that transcription factor ZFP38 has the potential to regulate transcription during meiosis. In this study, we generated Zfp38 conditional knockout mice (Zfp38 flox/flox, Stra8-Cre, hereafter called Zfp38 cKO) and found that spermatogenesis did not progress beyond meiosis prophase I in Zfp38 cKO mice. Using a chromosomal spread technique, we observed that Zfp38 cKO spermatocytes exhibited a failure in chromosomal synapsis observed by SYCP1/SYCP3 double staining. Progression of DNA double-strand breaks (DSB) repair is disrupted in Zfp38 cKO spermatocytes, as revealed by γ-H2AX, RAD51 and MLH1 staining. Furthermore, the mRNA and protein levels of DSB repair enzymes and factors that guide their loading onto sites of DSBs, such as RAD51, DMC1, RAD51, TEX15 and PALB2, were significantly reduced in Zfp38 cKO spermatocytes. Taken together, our data suggest that ZFP38 is critical for the chromosomal synapsis and DSB repairs partially via its regulation of DSB repair-associated protein expression during meiotic progression in mouse.

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Cai-Xia Yang, Zhao-Hui Kou, Kai Wang, Yan Jiang, Wen-Wei Mao, Qing-Yuan Sun, Hui-Zhen Sheng and Da-Yuan Chen

In cloned animals where somatic cell nuclei and oocytes are from the same or closely related species, the mitochondrial DNA (mtDNA) of the oocyte is dominantly inherited. However, in nuclear transfer (NT) embryos where nuclear donor and oocyte are from two distantly related species, the distribution of the mtDNA species is not known. Here we determined the levels of macaque and rabbit mtDNAs in macaque embryos reprogrammed by rabbit oocytes. Quantification using a real-time PCR method showed that both macaque and rabbit mtDNAs coexist in NT embryos at all preimplantation stages, with maternal mtDNA being dominant. Single NT embryos at the 1-cell stage immediately after fusion contained 2.6 × 104 copies of macaque mtDNA and 1.3 × 106 copies of rabbit mtDNA. Copy numbers of both mtDNA species did not change significantly from the 1-cell to the morula stages. In the single blastocyst, however, the number of rabbit mtDNA increased dramatically while macaque mtDNA decreased. The ratio of nuclear donor mtDNA to oocyte mtDNA dropped sharply from 2% at the 1-cell stage to 0.011% at the blastocyst stage. These results suggest that maternal mtDNA replicates after the morula stage.

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Jun Shao, Bing Zhang, Jia-Jun Yu, Chun-Yan Wei, Wen-Jie Zhou, Kai-Kai Chang, Hui-Li Yang, Li-Ping Jin, Xiao-Yong Zhu and Ming-Qing Li

Macrophages play an important role in the origin and development of endometriosis. Estrogen promoted the growth of decidual stromal cells (DSCs) by downregulating the level of interleukin (IL)-24. The aim of this study was to clarify the role and mechanism of IL-24 and its receptors in the regulation of biological functions of endometrial stromal cells (ESCs) during endometriosis. The level of IL-24 and its receptors in endometrium was measured by immunohistochemistry. In vitro analysis was used to measure the level of IL-24 and receptors and the biological behaviors of ESCs. Here, we found that the expression of IL-24 and its receptors (IL-20R1 and IL-20R2) in control endometrium was significantly higher than that in eutopic and ectopic endometrium of women with endometriosis. Recombinant human IL-24 (rhIL-24) significantly inhibited the viability of ESCs in a dosage-dependent manner. Conversely, blocking IL-24 with anti-IL-24 neutralizing antibody promoted ESCs viability. In addition, rhIL-24 could downregulate the invasiveness of ESCs in vitro. After co-culture, macrophages markedly reduced the expression of IL-24 and IL-20R1 in ESCs, but not IL-22R1. Moreover, macrophages significantly restricted the inhibitory effect of IL-24 on the viability, invasion, the proliferation relative gene Ki-67, proliferating cell nuclear antigen (PCNA) and cyclooxygenase2 (COX-2), and the stimulatory effect on the tumor metastasis suppressor gene CD82 in ESCs. These results indicate that the abnormally low level of IL-24 in ESCs possibly induced by macrophages may lead to the enhancement of ESCs’ proliferation and invasiveness and contribute to the development of endometriosis.

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Hua-Yu Lian, Yan Gao, Guang-Zhong Jiao, Ming-Ju Sun, Xiu-Fen Wu, Tian-Yang Wang, Hong Li and Jing-He Tan

In this study, using a mouse model, we tested the hypothesis that restraint stress would impair the developmental potential of oocytes by causing oxidative stress and that antioxidant supplementation could overcome the adverse effect of stress-induced oxidative stress. Female mice were subjected to restraint stress for 24 h starting 24 h after equine chorionic gonadotropin injection. At the end of stress exposure, mice were either killed to recover oocytes for in vitro maturation (IVM) or injected with human chorionic gonadotropin and caged with male mice to observe in vivo development. The effect of antioxidants was tested in vitro by adding them to IVM medium or in vivo by maternal injection immediately before restraint stress exposure. Assays carried out to determine total oxidant and antioxidant status, oxidative stress index, and reactive oxygen species (ROS) and glutathione levels indicated that restraint stress increased oxidative stress in mouse serum, ovaries, and oocytes. Whereas the percentage of blastocysts and number of cells per blastocyst decreased significantly in oocytes from restraint-stressed mice, addition of antioxidants to IVM medium significantly improved their blastocyst development. Supplementation of cystine and cysteamine to IVM medium reduced ROS levels and aneuploidy while increasing glutathione synthesis and improving pre- and postimplantation development of oocytes from restraint-stressed mice. Furthermore, injection of the antioxidant epigallocatechin gallate into restraint-stressed mice significantly improved the blastocyst formation and postimplantation development of their oocytes. In conclusion, restraint stress at the oocyte prematuration stage impaired the developmental potential of oocytes by increasing oxidative stress and addition of antioxidants to IVM medium or maternal antioxidant injection overcame the detrimental effect of stress-induced oxidative stress. The data reported herein are helpful when making attempts to increase the chances of a successful outcome in human IVF, because restraint was applied at a stage similar to the FSH stimulation period in a human IVF program.