Spermatogenesis, an elaborate and male-specific process in adult testes by which a number of spermatozoa are produced constantly for male fertility, relies on spermatogonial stem cells (SSCs). As a sub-population of undifferentiated spermatogonia, SSCs are capable of both self-renewal (to maintain sufficient quantities) and differentiation into mature spermatozoa. SSCs are able to convert to pluripotent stem cells during in vitro culture, thus they could function as substitutes for human embryonic stem cells without ethical issues. In addition, this process does not require exogenous transcription factors necessary to produce induced-pluripotent stem cells from somatic cells. Moreover, combining genetic engineering with germ cell transplantation would greatly facilitate the generation of transgenic animals. Since germ cell transplantation into infertile recipient testes was first established in 1994, in vivo and in vitro study and manipulation of SSCs in rodent testes have been progressing at a staggering rate. By contrast, their counterparts in domestic animals, despite the failure to reach a comparable level, still burgeoned and showed striking advances. This review outlines the recent progressions of characterization, isolation, in vitro propagation, and transplantation of spermatogonia/SSCs from domestic animals, thereby shedding light on future exploration of these cells with high value, as well as contributing to the development of reproductive technology for large animals.
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Yi Zheng, Yaqing Zhang, Rongfeng Qu, Ying He, Xiue Tian, and Wenxian Zeng
Ying Zhang, Camila Bruna de Lima, Rémi Labrecque, and Marc-Andre Sirard
Subfertile bulls may cause huge economic losses in dairy production since their semen could be used to inseminate thousands of cows by artificial insemination. This study adopted whole-genome enzymatic methyl sequencing and aimed to identify candidate DNA methylation markers in bovine sperm that correlate with bull fertility. Twelve bulls were selected (High Bull Fertility = 6; Low Bull Fertility = 6) based on the industry’s internally used Bull Fertility Index (BFI). After sequencing, a total of 450 CpG had a DNA methylation difference higher than 20% (q<0.01) had been screened. The sixteen most significant differentially methylated regions(DMRs) were identified using a 10% methylation difference cut-off (q<5.88x10-16). Interestingly, most of the differentially methylated cytosines (DMCs) and DMRs were distributed on the X and Y chromosomes, demonstrating that the sex chromosomes play essential roles in bull fertility. Additionally, the functional classification showed that the beta-defensin family, zinc finger protein family, and olfactory and taste receptors could be clustered. Moreover, the enriched G protein-coupled receptors such as neurotransmitter receptors, taste receptors, the olfactory receptor family, and ion channels indicated that the acrosome reaction and capacitation processes are pivotal for bull fertility. In conclusion, this study identified the sperm-derived bull fertility-associated DMRs and DMCs at the whole genome level, which could complement and integrate into the existing genetic evaluation methods, increasing our decisive capacity to select good bulls and explain bull fertility better in the future.
Yingying Zhou, Yangying Peng, Qingqing Xia, Dewen Yan, Huiping Zhang, Lingmin Zhang, Ying Chen, Xiumin Zhao, and Jie Li
Indian hedgehog (Ihh) signaling regulates endometrial receptivity and is an indispensable mediator of embryonic implantation. Hedgehog signaling is known to regulate autophagy, and aberrant regulation of autophagy is critically implicated in the pathogenesis of endometriosis and adenomyosis. However, potential dysregulation of Ihh signaling and its role in autophagy modulation in these diseases remain obscure. In this study, we found that components of Ihh signaling were significantly decreased, whereas the autophagy marker protein, LC3BII, was significantly increased in endometrial tissues of women with endometriosis or adenomyosis. Inhibition of Ihh signaling with the small-molecule inhibitor GANT61 or Gli1 silencing in primary endometrial stromal cells increased autophagic activity, as measured by LC3 turnover assay and tandem mCherry-eGFP-LC3B fluorescence microscopy. Furthermore, we observed that GANT61 treatment significantly attenuated hydrogen peroxide-induced cell death, whereas disruption of autophagy with chloroquine diminished this effect. Collectively, these findings reveal that Ihh signaling is suppressed in endometrial tissues of patients with endometriosis or adenomyosis. This abnormal decrease may contribute to endometrial autophagy activation, which may promote aberrant survival of endometrial cells in ectopic sites in these two gynecological diseases.
Sha Peng, Jing Li, Chenglin Miao, Liwei Jia, Zeng Hu, Ping Zhao, Juxue Li, Ying Zhang, Qi Chen, and Enkui Duan
Dickkopf-1 (Dkk1) is one of the secreted antagonists in the canonical Wnt signaling pathway. It plays important roles in diverse developmental processes. However, the role of Dkk1 in trophoblast cell invasion during placentation remains unclear. In this study, we found that Dkk1 was mainly expressed in maternal decidual tissue but trivially in ectoplacental cones (EPCs) in day 8 post coitum (p.c.) pregnant mouse uterus and that the efficiency of EPC attachment and outgrowth was increased when co-cultured with decidual cells, which secreted Dkk1, and this enhancement was abolished by pretreating decidual cells with Dkk1 blocking antibody before co-culture experiment. This indicates that Dkk1 secreted by decidual cells plays an important role in trophoblast cell invasion. Indeed, when recombinant mouse Dkk1 was added to EPCs in vitro, the efficiency of attachment and outgrowth was increased. Migration of EPCs toward the decidua was retarded when antisense Dkk1 oligonucleotide (ODN) was administered via intrauterine injection in vivo. Furthermore, the active β-catenin nuclear location was lost when we treated cultured EPCs with recombinant mouse Dkk1, and the efficiency of EPCs attachment and outgrowth was obviously increased when we treated cultured EPCs with antisense β-catenin ODN. Taken together, Dkk1 secreted by decidual cells may induce trophoblast cell invasion in the mouse and β-catenin may be involved in such functions of Dkk1.
Liu Shi-fan, Wang Zhong-xing, Yuan Yao-e, Bing Sheng-min, Zhang Bei-zhu, Wu Jin-zhi, Wu Yi-e, and Peng Xin-ying
Summary. The concentrations of LH, FSH, prolactin, oestradiol and progesterone in serum were measured daily during the menstrual cycle of 100 normal Chinese women. The cyclic changes in LH, FSH, oestradiol and progesterone were typical of ovulatory cycles in women of other ethnic groups as reported in the literature. The geometric mean of the LH midcycle peak value was 51·64 i.u./l, the FSH mid-cycle peak value was 11 ·52 i.u./l, the preovulatory oestradiol peak was 1229·12 pmol/1, and the progesterone luteal maximum was 53·27 nmol/1. The cyclic changes of prolactin concentrations were irregular: the value at mid-cycle was significantly higher than that at the follicular or luteal phases.
A correlation between the length of the cycle and mean concentrations of LH and oestradiol at different stages throughout the cycle was shown.
Shijia Ying, Ziyu Wang, Changlong Wang, Haitao Nie, Dongyang He, Ruoxin Jia, Yongcong Wu, Yongjie Wan, Zhengrong Zhou, Yibo Yan, Yanli Zhang, and Feng Wang
This study investigated the effects of short-term food restriction or supplementation on folliculogenesis and plasma and intrafollicular metabolite and hormone concentrations. Ewes were randomly assigned to three groups: the control group received a maintenance diet (M) while the supplemented group and restricted group received 1.5×M and 0.5×M respectively on days 6–12 of their estrous cycle. Estrus was synchronized by intravaginal progestogen sponges for 12 days. On days 7–12, blood samples were taken. After slaughter, the ovarian follicles were classified and the follicular fluid was collected. Compared with restriction, supplementation shortened the estrous cycle length, decreased the number of follicles 2.5–3.5 mm and follicular fluid estradiol (E2) concentration, increased the number of follicles >3.5 mm and plasma glucose, insulin and glucagon concentrations, and augmented the volume of follicles >2.5 mm. Restricted ewes had higher intrafollicular insulin concentration, but it was similar to that of supplemented ewes. Compared with follicles ≤2.5 mm, the intrafollicular glucose and E2 concentrations were increased and the testosterone, insulin, and glucagon concentrations and lactate dehydrogenase (LDH) activity were decreased in follicles >2.5 mm. Only in restricted ewes were intrafollicular LDH and testosterone concentrations in follicles ≤2.5 mm not different from those in follicles ≤2.5 mm. In conclusion, the mechanism by which short-term dietary restriction inhibits folliculogenesis may involve responses to intrafollicular increased E2, testosterone, and LDH levels in late-stage follicles. This may not be due to the variation of intrafollicular insulin level but rather due to decreased circulating levels of glucose, insulin, and glucagon.
Ma Tian-Zhong, Chen Bi, Zhang Ying, Jing Xia, Peng Cai-Ling, Zhang Yun-Shan, Huang Mei-Wen, and Niu Yan-Ru
Emx2 deletion impairs the growth and maintenance of the genital ridge. However, its role in subsequent germ cell differentiation during embryonic stages is unknown. Using a tamoxifen-inducible Cre-loxP mouse model (Emx2 flox/flox, Cre-ER TM, hereafter called as Emx2 knockdown), we showed that germ cell differentiation was impaired in Emx2-knockdown testes. Representative characteristics of male germ cell differentiation, including a reduced ability to form embryonic germ (EG) cell colonies in vitro, down-regulation of pluripotency markers and G1/G0 arrest, did not occur in Emx2-knockdown testes. Furthermore, FGF9 and NODAL signalling occurred at abnormally high levels in Emx2-knockdown testes. Both blocking FGF9 signalling with SU5402 and inhibiting NODAL signalling with SB431542 allowed germ cells from Emx2-knockdown testes to differentiate in vitro. Therefore, EMX2 in somatic cells is required to trigger germ cell differentiation in XY foetuses, posterior to its previously reported role in the growth and maintenance of the genital ridge.
Yufei Wang, Haoya Chang, Qifu He, Yaxing Xue, Kang Zhang, Jian Kang, Ying Wang, Zhiming Xu, Yong Zhang, and Fusheng Quan
Oocyte vitrification has significantly improved the survival rate and become the mainstream method for cryopreserving oocytes. Previous studies have demonstrated that the ultrastructure, mitochondrial function, DNA methylation, and histone modification exhibit an irreversible effect after oocyte vitrification. However, little is known about the effects of oocyte vitrification on glucose transport and metabolism. This study aims to determine whether mouse oocyte vitrification causes abnormal glucose metabolism and identify a strategy to correct abnormal glucose metabolism. Furthermore, this study further investigates the effects of oocyte vitrification on glucose uptake, and glucose metabolism, and energy levels. The results indicated that vitrification significantly reduced the glucose transport activity, NADPH, glutathione, and ATP levels, and increased reactive oxygen species levels in oocytes (P < 0.01). Vitrification also reduced the expression of glucose transporter isoform 1 (GLUT1) (P < 0.01). Adding a GLUT1 inhibitor reduced the glucose uptake capacity of oocytes. Furthermore, the inclusion of vitamin C into thawing and culture solutions restored abnormal glucose transportation and metabolism and improved the survival, two-cell embryo, and blastocyst rates of the vitrified groups via parthenogenesis (P < 0.05). Overall, this method may improve the quality and efficiency of oocyte vitrification.
Xue Zhang, Bo-Yin Tan, Shuang Zhang, Qian Feng, Ying Bai, Shi-Quan Xiao, Xue-Mei Chen, Jun-Lin He, Xue-Qing Liu, Ying-Xiong Wang, Yu-Bin Ding, and Fang-Fang Li
Decidualization of uterine stromal cells plays an important role in the establishment of normal pregnancy. Previous studies have demonstrated that Acyl-CoA binding protein (Acbp) is critical to cellular proliferation, differentiation, mitochondrial functions, and autophagy. The characterization and physiological function of Acbp during decidualization remain largely unknown. In the present study, we conducted the expression profile of Acbp in the endometrium of early pregnant mice. With the occurrence of decidualization, the expression of Acbp gradually increased. Similarly, Acbp expression was also strongly expressed in decidualized cells following artificial decidualization, both in vivo and in vitro. We applied the mice pseudopregnancy model to reveal that the expression of Acbp in the endometrium of early pregnant mice was not induced by embryonic signaling. Moreover, P4 significantly upregulated the expression of Acbp, whereas E2 appeared to have no regulating effect on Acbp expression in uterine stromal cells. Concurrently, we found that interfering with Acbp attenuated decidualization, and that might due to mitochondrial dysfunctions and the inhibition of fatty acid oxidation. The level of autophagy was increased after knocking down Acbp. During induced decidualization, the expression of ACBP was decreased with the treatment of rapamycin (an autophagy inducer), while increased with the addition of Chloroquine (an autophagy inhibitor). Our work suggests that Acbp plays an essential role in the proliferation and differentiation of stromal cells during decidualization through regulating mitochondrial functions, fatty acid oxidation, and autophagy.
Ying Huang, Jiang-Man Gao, Chun-Mei Zhang, Hong-Cui Zhao, Yue Zhao, Rong Li, Yang Yu, and Jie Qiao
Polycystic ovary syndrome (PCOS) is a common reproductive disorder that has many characteristic features including hyperandrogenemia, insulin resistance and obesity, which may have significant implications for pregnancy outcomes and long-term health of women. Daughters born to PCOS mothers constitute a high-risk group for metabolic and reproductive derangements, but no report has described potential growth and metabolic risk factors for such female offspring. Hence, we used a mouse model of dehydroepiandrosterone (DHEA)-induced PCOS to study the mechanisms underlying the pathology of PCOS by investigating the growth, developmental characteristics, metabolic indexes and expression profiles of key genes of offspring born to the models. We found that the average litter size was significantly smaller in the DHEA group, and female offspring had sustained higher body weight, increased body fat and triglyceride content in serum and liver; they also exhibited decreased energy expenditure, oxygen consumption and impaired glucose tolerance. Genes related to glucolipid metabolism such as Pparγ, Acot1/2, Fgf21, Pdk4 and Inhbb were upregulated in the liver of the offspring in DHEA group compared with those in controls, whereas Cyp17a1 expression was significantly decreased. However, the expression of these genes was not detected in male offspring. Our results show that female offspring in DHEA group exhibit perturbed growth and glucolipid metabolism that were not observed in male offspring.