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  • Author: K. Yang x
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Q Qiu, M Yang, B K Tsang and A Gruslin

Epidermal growth factor (EGF) is present in the maternal-fetal environment and has an important role in placental development. Matrix metalloproteinase-9 (MMP-9) expression/activation is a pre-requisite in extravillous trophoblast invasion. Whereas EGF up-regulates MMP-9 activity in a variety of cell types, there is no direct evidence for the stimulation of MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) secretion by EGF in extravillous trophoblasts. In addition, the signalling pathways involved in this regulation are not clear. In the present study, we have examined the possible involvement of the phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways in the regulation of the MMP-9/TIMP-1 system by EGF in vitro. We used a well-established invasive extravillous trophoblast cell line (HTR8/Svneo) and measured gene and protein expression by semi-quantitative RT-PCR and western analysis respectively. MMP activity was determined by zymography. We showed for the first time that EGF activated both PI3K/Akt and MAPK/extracellular-signal regulated kinase (ERK) signalling in HTR8/SVneo, and increased both MMP-9 and TIMP-1 mRNAs and protein concentrations. Interfering with either signalling pathway via PI3K inhibitor LY294002 or MEK inhibitor U0126 in EGF-stimulated HTR8/SVneo cells blocked the induction of MMP-9 and TIMP-1. LY294002 inhibited Akt phosphorylation, but had no effect on ERK phosphorylation; U0126 suppressed ERK phosphorylation without interfering with the phosphorylation of Akt. In addition, expression of constitutively active Akt (Myr-Akt1, Myr-Akt2, Myr-Akt3) was not sufficient to induce proMMP-9 and TIMP-1 secretion. Our results suggest that the activation of both PI3K and MAPK pathways in extravillous trophoblasts is necessary for the up-regulation of MMP-9 and TIMP-1 expression by EGF.

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Yuewen Zhao, Xiaojing Yang, Zongchao Jia, Robert L Reid, Pierre Leclerc and Frederick W K Kan

The mammalian oviduct synthesizes and secretes a major glycoprotein known as oviductin (OVGP1), which has been shown to interact with gametes and early embryos. Here we report the use of recombinant DNA technology to produce, for the first time, the secretory form of human OVGP1 in HEK293 cells. HEK293 colonies stably expressing recombinant human OVGP1 (rHuOVGP1) were established by transfecting cells with an expression vector pCMV6-Entry constructed with OVGP1 cDNA. Large quantities of rHuOVGP1 were obtained from the stably transfected cells using the CELLSPIN cell cultivation system. A two-step purification system was carried out to yield rHuOVGP1 with a purity of >95%. Upon gel electrophoresis, purified rHuOVGP1 showed a single band corresponding to the 120–150 kDa size range of human OVGP1. Mass spectrometric analysis of the purified rHuOVGP1 revealed its identity as human oviductin. Immunofluorescence showed the binding of rHuOVGP1 to different regions of human sperm cell surfaces in various degrees of intensity. Prior treatment of sperm with 1% Triton X-100 altered the immunostaining pattern of rHuOVGP1 with an intense immunostaining over the equatorial segment and post-acrosomal region as well as along the length of the tail. Addition of rHuOVGP1 in the capacitating medium further enhanced tyrosine phosphorylation of sperm proteins in a time-dependent manner. After 4-h incubation in the presence of rHuOVGP1, the number of acrosome-reacted sperm induced by calcium ionophore significantly increased. The successful production of rHuOVGP1 can now facilitate the study of the role of human OVGP1 in fertilization and early embryo development.

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Y Du, C S Pribenszky, M Molnár, X Zhang, H Yang, M Kuwayama, A M Pedersen, K Villemoes, L Bolund and G Vajta

The purpose of the present study was to improve cryotolerance using high hydrostatic pressure (HHP) pretreatment of porcine in vitro matured (IVM) oocytes, to facilitate their further developmental competence after parthenogenetic activation. A total of 1668 porcine IVM oocytes were used in our present study. The pressure tolerance and optimal duration of recovery after HHP treatment were determined. Oocytes were treated with either 20 or 40 MPa (200 and 400 times greater than atmospheric pressure) for 60 min, with an interval of 10, 70, and 130 min between pressure treatment and subsequent vitrification under each pressure parameter. Oocytes from all vitrification groups had much lower developmental competence than fresh oocytes (P<0.01) measured as cleavage and blastocyst rates. However, significantly higher blastocyst rates (P<0.01) were obtained in the groups of 20 MPa pressure, with either 70 (11.4±2.4%) or 130 (13.1±3.2%) min recovery, when compared with the vitrification control group without HHP treatment where no blastocysts were obtained. The influence of temperature at HHP treatment on further embryo development was also investigated. Treatments of 20 MPa with 70 min recovery were performed at 37 °C or 25 °C. Oocytes pressurized at 37 °C had a significantly higher blastocyst (14.1±1.4%) rate than those treated at 25 °C (5.3±1.1%; P<0.01). Our results demonstrate that HHP pretreatment could considerably improve the developmental competence of vitrified pig in vitro matured (IVM) oocytes. The HHP pretreatment will be tested as a means to improve survival and developmental competence at different developmental stages in different species including humans.