-
Jing Wen,
Hua Zhang,
Ge Li,
Guanping Mao, Xiufen Chen,
Jianwei Wang,
Meng Guo,
Xinyi Mu,
Hong Ouyang,
Meijia Zhang,
Guoliang Xia
[show abstract]
[hide abstract]
ABSTRACT: Partitioning-defective proteins (PAR) are detected to express mainly in the cytoplast, and play an important role in cell polarity. However, we showed here that PAR6, one kind of PAR protein, was localized in the nuclei of mouse oocytes that formed primordial follicles during the perinatal period, suggesting a new role of PAR protein. It is the first time we found that, in mouse fetal ovaries, PAR6 appeared in somatic cell cytoplasm and fell weak when somatic cells invaded germ cell cysts at 17.5 days post coitus (dpc). Meanwhile, the expression of PAR6 was observed in cysts, and became strong in the nuclei of some germ cells at 19.5 dpc and all primordial follicular oocytes at 3 day post parturition (dpp), and then obviously declined when the primordial follicles entered the folliculogenic growth phase. During the primordial follicle pool foundation, the number of PAR6 positive germ cells remained steady and was consistent with that of formed follicles at 3 dpp. There were no TUNEL (apoptosis examination) positive germ cells stained with PAR6 at any time studied. The number of follicles significantly declined when 15.5 dpc ovaries were treated with the anti-PAR6 antibody and PAR6 RNA interference. Carbenoxolone (CBX, a known blocker of gap junctions) inhibited the expression of PAR6 in germ cells and the formation of follicles. Our results suggest that PAR6 could be used as a potential marker of germ cells for the primordial follicle formation, and the expression of PAR6 by a gap junction-dependent process may contribute to the formation of primordial follicles and the maintenance of oocytes at the diplotene stage.
PLoS ONE 01/2009; 4(10):e7372. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cytochrome P450 lanosterol 14alpha-demethylase (CYP51) is a key enzyme in sterols and steroids biosynthesis that can induce meiotic resumption in mouse oocytes. The present study investigated the expression mechanism and function of CYP51 during FSH-induced mouse cumulus oocyte complexes (COCs) meiotic resumption. FSH increased cAMP-dependent protein kinase (PKA) RIIbeta level and induced cAMP response element-binding protein (CREB) phosphorylation and CYP51 expression in cumulus cells before oocyte meiotic resumption. Moreover, CYP51 and epidermal growth factor (EGF)-like factor [amphiregulin (AR)] expression were blocked by (2)-naphthol-AS-Ephosphate (KG-501) (a drug interrupting the formation of CREB functional complex). KG-501 and RS21607 (a specific inhibitor of CYP51 activity) inhibited oocyte meiotic resumption, which can be partially rescued by progesterone. These two inhibitors also inhibited FSH-induced MAPK phosphorylation. EGF could rescue the suppression by KG-501 but not RS21607. Furthermore, type II PKA analog pairs, N(6)-monobutyryl-cAMP plus 8-bromo-cAMP, increased PKA RIIbeta level and mimicked the action of FSH, including CREB phosphorylation, AR and CYP51 expression, MAPK activation, and oocyte maturation. All these data suggest that CYP51 plays a critical role in FSH-induced meiotic resumption of mouse oocytes. CYP51 and AR gene expression in cumulus cells are triggered by FSH via a type II PKA/CREB-dependent signal pathway. Our study also implicates that CYP51 activity in cumulus cells participates in EGF receptor signaling-regulated oocyte meiotic resumption.
Molecular Endocrinology 08/2008; 22(7):1682-94. · 4.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: It is proved that epidermal growth factor (EGF)-like factors mediate gonadotropin-induced rodent oocyte maturation via EGF receptor (EGFR). However, the detail kinetics and signal pathway between FSH and EGF/EGFR is not clear in large animals. In the present study, we investigated the roles of EGFR and protein kinase C (PKC) in FSH-induced porcine oocyte meiotic resumption. Porcine cumulus-oocyte complexes were cultured in NCSU37 medium containing 10% porcine follicular fluid and germinal vesicle breakdown (meiotic resumption) was detected after different treatments. The results showed that EGF-like factor amphiregulin (AR) and EGFR mRNA were expressed in porcine cumulus cells, but not oocytes. FSH significantly induced AR mRNA expression with maximum at 4 h and activated EGFR phosphorylation at 8 h. AR (1-100 ng/ml) dose-dependently induced meiosis resumption of porcine oocyte. The specific EGFR inhibitor, AG1478, but not AG43 (the inactive analog of AG1478), completely blocked FSH, EGF, and AR-induced oocyte meiotic resumption; the inhibitory effect of AG1478 on FSH action gradually decreased when the inhibitor was added at 6 h or later and disappeared when it was added at 11 h; EGF reversed the inhibitory effect on FSH when AG1478 was added within 6 h. FSH triggered porcine oocyte meiotic resumption (at 20 h) later than that of EGF and AR (at 18 h). All these results supported that endogenously produced EGFR activator(s), possibly AR (maximum at 4 h) and EGFR activation (began at 6 h and finished within 11 h), in cumulus cells is necessary for FSH-induced porcine oocyte meiotic resumption (began at 18 h). Furthermore, PKC activator PMA mimicked but PKC inhibitor chelerythrine chloride inhibited FSH action, and AG1478 also suppressed PMA-induced porcine oocyte meiotic resumption. These data together suggested that EGFR activation, by PKC signal pathway, participates in FSH-induced porcine oocyte meiotic resumption.
Journal of Endocrinology 06/2008; 197(2):409-19. · 3.55 Impact Factor
-
Ping Tai,
Junpeng Wang,
Huali Jin,
Xiaoming Song,
Jun Yan,
Youmin Kang,
Lin Zhao,
Xiaojin An,
Xiaogang Du, Xiufen Chen,
Songbo Wang,
Guoliang Xia,
Bin Wang
[show abstract]
[hide abstract]
ABSTRACT: Naturally occurring CD4+CD25+ regulatory T cells (Treg) exert an important role in mediating maternal tolerance to the fetus during pregnancy, and this effect might be regulated via maternal estrogen secretion. Although estrogen concentration in the pharmaceutical range has been shown to drive expansion of CD4+CD25+ Treg cells, little is known about how and through what mechanisms E2 within the physiological concentration range of pregnancy affects this expansion. Using in vivo and in vitro mouse models in these experiments, we observed that E2 at physiological doses not only expanded Treg cell in different tissues but also increased expression of the Foxp3 gene, a hallmark for CD4+CD25+ Treg cell function, and the IL-10 gene as well. Importantly, our results demonstrate that E2, at physiological doses, stimulated the conversion of CD4+CD25- T cells into CD4+CD25+ T cells which exhibited enhanced Foxp3 and IL-10 expression in vitro. Such converted CD4+CD25+ T cells had similar regulatory function as naturally occurring Treg cells, as demonstrated by their ability to suppress naïve T cell proliferation in a mixed lymphocyte reaction. We also found that the estrogen receptor (ER) exist in the CD4+CD25- T cells and the conversion of CD4+CD25- T cells into CD4+CD25+ T cells stimulated by E2 could be inhibited by ICI182,780, a specific inhibitor of ER(s). This supports that E2 may directly act on CD4+CD25- T cells via ER(s). We conclude that E2 is a potential physiological regulatory factor for the peripheral development of CD4+CD25+ Treg cells during the implantation period in mice.
Journal of Cellular Physiology 03/2008; 214(2):456-64. · 3.87 Impact Factor
-
Songbo Wang,
Gang Ning, Xiufen Chen,
Jiange Yang,
Hong Ouyang,
Hua Zhang,
Ping Tai,
Xinyi Mu,
Bo Zhou,
Meijia Zhang,
Guoling Xia
[show abstract]
[hide abstract]
ABSTRACT: Phosphodiesterase type 5 (PDE5), a cGMP specific, cGMP binding phosphodiesterase, specifically hydrolyzes cGMP to 5'-GMP. Here, we examine the distribution of PDE5 in mouse ovary and its effects on spontaneous maturation of mouse oocytes. PDE5 is present in oocytes and cumulus cells of big, antral follicles. Inhibition of activity of PDE5 significantly and reversibly inhibits spontaneous maturation of cumulus-oocyte complexes (COCs). Suppressive effect of PDE5 on spontaneous maturation of COCs is not blocked by the inhibitor of cGMP-dependent protein kinase (PKG). While Sildenafil, an inhibitor of PDE5, has a poor effect on cGMP levels, it significantly increases cAMP levels. These results suggest that the activity of PDE5 plays a role in regulating spontaneous maturation of mouse oocytes and imply that an interaction between cGMP and cAMP signal is involved in this process.
Frontiers in Bioscience 02/2008; 13:7087-95. · 3.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Food deprivation suppresses ovulation. Although nutritional elements are responsible for this suppression, it is not clear whether energy metabolism has any effect on oocyte development under these circumstances. The aim of the present study was to determine which nutritional element is responsible for the effect of acute fasting on mouse ovulation and how oocyte development is affected. The results demonstrate that 64 h food deprivation blocks mouse ovulation. This was reversed by glucose feeding, oil feeding or short-term feeding, all of which elevated serum glucose levels. Furthermore, 48 h food deprivation inhibited follicle-stimulating hormone-induced oocyte maturation in vitro. However, 48 h glucose feeding increased serum glucose levels and restored oocyte maturation. Food deprivation increased serum progesterone levels and decreased serum oestradiol levels. Food deprivation also impaired follicle development, caused the death of oocytes and attenuated glucose consumption by cumulus-oocyte complexes. Taken together, the results indicate that: (1) the suppression of ovulation by acute fasting may be due to the control of oocyte development; and (2) maintaining serum glucose concentrations at a certain level is important for normal ovulation.
Reproduction Fertility and Development 02/2008; 20(6):703-12. · 2.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Lanosterol 14alpha-demethylase (LDM) is expressed ubiquitously in all mammals and is important in cholesterol biosynthesis. However, whether LDM expression is involved in the interaction between uterus and embryo during implantation remains unknown. In the present study, the expression of LDM was investigated in mouse embryo and uterus during the peri-implantation period using confocal microscopy, immunohistochemistry and western blot methods. Further, regulation of LDM expression was investigated in pseudopregnancy, delayed implantation, artificial decidualisation and ovariectomisation using 17beta-oestradiol and progesterone treatment mouse models. The results showed that LDM was selectively expressed in preimplantation embryos and the uterine subluminal stroma surrounding the implanting blastocyst on Day 5 of pregnancy. No corresponding signal was detected in the uterus on Day 5 of pseudopregnancy. Most notably, once delayed implantation was terminated by oestrogen treatment and the embryo implanted, a high level of LDM expression was induced in the subluminal stroma surrounding the implanting blastocyst, whereas no corresponding signal was detected in the delayed implantation uterus. A high level of LDM expression was observed in the uterus decidua on Days 6-8 of pregnancy. Furthermore, LDM expression was induced in the uterine stroma under artificial decidualisation. Oestrogen, but not progesterone, treatment induced a high level of LDM expression in the uterus of ovariectomised mice. These results indicate that LDM is closely related to mouse embryo implantation and can be upregulated by oestrogen.
Reproduction Fertility and Development 02/2008; 20(8):964-72. · 2.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In the process of oocyte maturation, gonadotrophins are believed as main stimulators for oocyte meiosis resumption. However, which gonadotrophin (i.e. FSH or LH) is the key hormone in this process is still unknown. This study indicated a close relationship between LH and FSH on activating meiotic maturation of oocyte in vitro. FSH efficiently induced oocyte meiosis at concentration of 50 IU/L, while LH alone had no effect on oocyte meiotic initiation. Using RT-PCR and in situ hybridization, a tight corelationship between FSH-stimulated oocyte meiotic resumption and LHR mRNA expression in cumulus cells was found. LHR mRNA was present in cumulus cells of oocyte-cumulus cell complexes. Except the expression of LHRs was present in cumulus cells surrounding all maturing oocytes, low level expression was also detected in cells associated with oocytes that were still at GV stage. Its expression was enhanced by FSH stimulation before oocyte maturation. However, LHRs did not express in cumulus cells associated with oocytes that were completely arrested at GV stage by IBMX. Furthermore, increased progesterone concentration was found in the medium in which CEOs were cultured with FSH and LH, but not in those with FSH or LH alone. LHR expression in cumulus cells increases with time in culture, and the levels of expression are enhanced in the presence of FSH. Oocyte meiotic resumption may create conditions favorable for LHR expression. LHR expression may be considered as a potential marker for oocytes maturation initiation.
Frontiers in Bioscience 02/2007; 12:1804-13. · 3.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The expression of lanosterol 14alpha-demethylase (LDM) in the mouse ovary after gonadotrophin administration was examined and the action of follicle fluid meiosis activating sterol (FF-MAS), derived from lanosterol by the action of LDM, on oocyte spontaneous maturation was also evaluated in cumulus cell enclosed oocytes (CEOs). Expression of LDM was primarily in oocytes in primordial and secondary follicles prior to administration of gonadotrophins, but obvious LDM expression was apparent in ovarian somatic cells 48 h after administration of equine chorionic gonadotrophin (eCG), especially in luteal and cumulus cells 54 h after eCG or 48 h after eCG plus 6 h after human chorionic gonadotrophin (hCG). The LDM expression in oocytes was only slightly elevated in larger growing follicles after eCG treatment. On the contrary, 48 h after hCG treatment, the elevated expression of LDM was only detected in interstitial cells. Therefore, eCG may be the primary gonadotrophin for LDM expression, and furthermore for production of FF-MAS in mouse cumulus cells (which are indispensable for oocyte maturation in vivo). Conversely, inhibitors of LDM, either 40 microM azalanstat or 50 microM RS-21745, significantly inhibited oocyte germinal vesicle breakdown (GVB) after 4h of in vitro culture; GVB rates decreased to 14 or 20%, compared to 90% in spontaneous maturation, respectively. There was no significant increase in GVB in CEOs following specific inhibitor of sterol Delta14-reductase and Delta7-reductase, AY9944-A-7 (5-100 microM), until marked oocytes degeneration appeared (50 microM). The phenomena may be ascribed to slow, passive accumulation of FF-MAS by AY9944-A-7, which cannot be associated with fast spontaneous progression. Furthermore, in spontaneous-matured CEOs, LDM was expressed preferentially in cumulus cells instead of oocytes. Therefore, FF-MAS may have a positive role in the spontaneous maturation of CEOs. In conclusion, there was an eCG-dependent dual LDM expression pattern on both oocytes and somatic cells in growing follicles in vivo, which may increase LDM expression and FF-MAS production in cumulus cells for oocyte maturation. For the first time, the inhibitory effect of LDM inhibitors on spontaneous maturation, together with the strong LDM expression in spontaneous matured CEOs, indicated that FF-MAS produced by cumulus cells might participate in spontaneous maturation of mouse CEOs.
Theriogenology 10/2006; 66(5):1156-64. · 1.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: As an important biological messenger, nitric oxide (NO) exhibits a wide range of effects during physiological and pathophysiological processes, including mammalian oocyte meiotic maturation. The present study investigated whether NO derived from two nitric oxide synthase (NOS) isoforms, inducible NOS (iNOS) or endothelial NOS (eNOS), is involved in the meiotic maturation of porcine oocytes. Meanwhile, the cumulus cells' function in meiotic maturation and their interaction with oocyte development and degeneration were also investigated using cumulus-enclosed oocytes (CEOs) and denuded oocytes (DOs). Different inhibitors for NOS were supplemented to the medium. Cumulus expansion, cumulus cell DNA fragmentation and oocyte meiotic resumption were evaluated 48 h after incubation. Aminoguanidine (AG), a selective inhibitor for iNOS, suppressed cumulus expansion and inhibited CEOs to resume meiosis (p < 0.05), but did not inhibit cumulus cell DNA fragmentation. Both Nomega-nitro-L-arginine (L-NNA) and Nomega-nitro-L-arginine methyl ester (L-NAME), inhibitors for both iNOS and eNOS, delayed cumulus expansion, inhibited cumulus cell DNA fragmentation and inhibited CEOs to resume meiosis. Such effects were not seen in DOs. These results indicate that iNOS-derived NO is necessary for cumulus expansion and meiotic maturation by mediating the function of the surrounding cumulus cells, and eNOS-derived NO is also involved in porcine meiotic maturation.
Zygote 02/2005; 13(1):1-9. · 1.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: As an important biological messenger, nitric oxide (NO) exhibits a wide range of effects during physiological and pathophysiological processes, including mammalian oocyte meiotic maturation. The present study investigated whether NO derived from two nitric oxide synthase (NOS) isoforms, inducible NOS (iNOS) or endothelial NOS (eNOS), is involved in the meiotic maturation of porcine oocytes. Meanwhile, the cumulus cells' function in meiotic maturation and their interaction with oocyte development and degeneration were also investigated using cumulus-enclosed oocytes (CEOs) and denuded oocytes (DOs). Different inhibitors for NOS were supplemented to the medium. Cumulus expansion, cumulus cell DNA fragmentation and oocyte meiotic resumption were evaluated 48 h after incubation. Aminoguanidine (AG), a selective inhibitor for iNOS, suppressed cumulus expansion and inhibited CEOs to resume meiosis (p<0.05), but did not inhibit cumulus cell DNA fragmentation. Both Nω-nitro-L-arginine (L-NNA) and Nω-nitro-L-arginine methyl ester (L-NAME), inhibitors for both iNOS and eNOS, delayed cumulus expansion, inhibited cumulus cell DNA fragmentation and inhibited CEOs to resume meiosis. Such effects were not seen in DOs. These results indicate that iNOS-derived NO is necessary for cumulus expansion and meiotic maturation by mediating the function of the surrounding cumulus cells, and eNOS-derived NO is also involved in porcine meiotic maturation.
Zygote 01/2005; 13(01):1 - 9. · 1.17 Impact Factor
