Multiple displacement amplification improves PGD for fragile X syndrome
We report an improvement in the PGD test for fragile X syndrome (FXS). Recently, multiple displacement amplification (MDA) has been reported to yield large amounts of DNA from single cells. Taking into account this technique, we developed a new PGD test for FXS, enabling combined analysis of linked polymorphic markers with the study of the non-expanded CGG repeat. Single cell amplification efficiency was first assessed on single lymphocytes. Amplification rate of the different markers ranged from 85 to 95% with an allele drop-out (ADO) rate comprised between 7 and 34%. Using this test, eight PGD cycles were carried out for six couples, and 37 embryos were analysed after preliminary MDA. Amplification rate was increased by this technique from 41 to 66% so that embryos with no results were rarer (14 versus 45% without MDA). Reliability of the test was considerably improved by combining direct with indirect genetic analysis. Furthermore, in cases of fully expanded alleles too large to be amplified by PCR, this test gives an internal amplification control. Embryonic transfers were carried out in all but one PGD cycles. One biochemical and one clinical pregnancy resulted, and a healthy child was born. This single diagnosis procedure could be suitable to most patients carrying FXS.
Haplotypes, mutations and male fertility: the story of the testis-specific ubiquitin protease USP26
Recently, mutations in the X-linked ubiquitin protease 26 (USP26) gene have been proposed to be associated with male infertility. In particular a 371insACA, 494T>C and 1423C>T haplotype, which results in a T123andash;124ins, L165S and H475Y amino acid change respectively, has been reported to be associated with Sertoli cell-only syndrome (SCOS) and an absence of sperm in the ejaculate. Here, we demonstrate that two of these changes actually correspond to the ancestral sequence of the gene and that the USP26 haplotype is present in significant frequencies in sub-Saharan African and South and East Asian populations, including in individuals with known fertility. This indicates that the allele is not associated with infertility. The pattern of frequency distribution of the derived haplotype (371delACA, 494T), which is present at high frequencies in most non-African populations could be interpreted as either a result of migration followed by simple genetic drift or alternatively as positive selection acting on the derived alleles. The latter hypothesis seems likely, because there is evidence of strong positive selection acting on the USP26 gene.
Identification of a calcium-dependent matrix metalloproteinase complex in rat chorioallantoid membranes during labour
The induction of the expression of matrix metalloproteinases (MMPs) and their extracellular activation are key processes in connective tissue degradation in the chorioallantoid membrane during rat labour. However, the regulatory mechanisms remain largely unknown. Here, we report the identification of a calcium-dependent high molecular weight complex composed of MMP-9, MMP-3, MMP-2, tissue inhibitor of metalloproteinase 1 (TIMP-1) and TIMP-2, identified by zymography and western blotting. Molecular sieve chromatography confirmed the presence of a complex of MMPs and TIMPs with an exclusion volume >670 kDa. Differential scanning calorimetry of the complex confirmed the existence of a macromolecular complex that unfolds with a broad transition; it is denatured over a wide range of temperatures and has a Tm of 72 deg;C in the presence of Ca2+. When denatured in the absence of Ca2+, there were at least eight transitions with Tms that corresponded to pro-MMP-9, MMP-9, pro-MMP-3, MMP-3, pro-MMP-2, MMP-2, TIMP-1 and TIMP-2. Co-localization of the same molecular components was demonstrated by confocal microscopy using cell-depleted chorioallantoid membranes. The assembly and disassembly of the complex can be reproduced at physiological concentrations of Ca2+. This complex provides a potential mechanism for the enzymatic regulation of MMPs, which may participate in connective tissue degradation leading to the rupture of the fetal membranes during labour.
Myometrial prostaglandin E2 synthetic enzyme mRNA expression: spatial and temporal variations with pregnancy and labour
We have investigated the hypothesis that the expression of the enzymes involved in PGE2 synthesis in the human uterus is co-ordinated. We have studied (i) the mRNA expression of the enzymes involved in PGE2 synthesis [phospholipases (cPLA2 and sPLA2), prostaglandin H synthase (PGHS)-2 and PG E synthases (PGES-1 and -2)] and their relationship to the expression of inflammatory cytokines in samples of myometrium obtained from pregnant women undergoing caesarean section (LSCS) either before or after the onset of labour at or before term; and (ii) the effect of IL-1ßbeta;, IL-6, TNF-, PGE2 and stretch on PGE2 enzyme mRNA expression. We found that cPLA2, sPLA2 and PGHS-2 mRNA expression were greater in labour samples; cPLA2, sPLA2, PGHS-2, PGES-1 and -2 mRNA expression were greater in lower- than upper-segment samples; and there was no effect of gestational age. PGHS-2 mRNA levels correlated with those of PGES-1, cPLA2, IL-1ßbeta; and IL-8; PGES-1 mRNA levels correlated with those of IL-1ßbeta;, IL-8 and cPLA2. In primary cultures of uterine myocytes, cPLA2 mRNA expression was increased by IL-1ßbeta; and IL-6; PGHS-2 mRNA expression was increased by IL-1ßbeta;, PGE2 and stretch; and PGES-1 mRNA expression was increased by IL-1ßbeta; only. These data show that labour is associated with increased expression of the enzymes involved in PGE2 synthesis and their expression is greater in the lower uterine segment. The presence of associations between the levels of PGE2 enzyme mRNA expression and the effects of IL-1ßbeta; suggest that their expression is co-ordinated and that IL-1ßbeta; is the responsible factor.
Epigenetic regulation of maspin expression in the human placenta
Maspin, a tumour suppressor gene, is differentially expressed in the human placenta. Decreased expression of maspin in the first trimester corresponds with the period of maximum trophoblast invasion, suggesting a role in cell invasion and motility. Although methylation of CpG islands regulates maspin expression in cancer cells, the mechanism of maspin regulation in the human placenta is unknown. Our objectives were to determine the role of epigenetic alterations in the regulation of maspin expression in the placenta. Placental samples obtained from 7 to 40 weeks’ gestation were used for bisulphite sequencing and chromatin immunoprecipitation (ChIP) PCR. There was no significant change in the methylation indices in the promoter region of maspin throughout gestation. The levels of histone modifications associated with transcriptionally active chromatin were significantly different in placental tissues from second and third trimester relative to those from first trimester. Addition of trichostatin A (TSA) to placental explants increased the maspin mRNA expression (8- to 20-fold), whereas addition of 5-aza-cytidine (5-AzaC) had no effect on maspin expression. Our data suggest that maspin expression in the human placenta is regulated by changes in histone tail modifications. This is the first report of selective histone modifications associated with differential placental gene expression in human gestation.
Tumour necrosis factor-{alpha} impairs chorionic gonadotrophin {beta}-subunit expression and cell fusion of human villous cytotrophoblast
Growth factors expressed at the fetal–maternal interface modulate hormone expression of placental trophoblasts. The aim of this study was to investigate the effects of different cytokines on hCG subunit mRNA expression in differentiating villous cytotrophoblasts. Quantitative real-time PCR revealed a 1.8- and 6.9-fold increase of hCG- and hCG-ß mRNA levels, respectively, between 36 and 60 h of term trophoblast syncytialization. Compared with controls, neither interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-10, IL-13 and IL-15 nor tumour necrosis factor (TNF)- significantly altered hCG- mRNA expression. Similarly, the ILs did not affect hCG-ß transcript levels. In contrast, TNF- suppressed hCG-ß mRNA 3.8- and 1.8-fold at 36 and 60 h of term trophoblast differentiation. Accordingly, hCG secretion was impaired by TNF- but not by the different ILs. Moreover, TNF- reduced luciferase expression of reporter plasmids harbouring the proximal hCG-ß5 promoter to 35 and 77%, respectively, in primary term trophoblasts and trophoblastic SHGPL-5 cells. In addition, counting of nuclei in syncytialized, desmoplakin-negative areas revealed a 1.9-fold reduction of term trophoblast fusion in the presence of TNF-. Similarly, floating explant cultures prepared from first trimester-denuded villi recovered the syncytium 2.8-fold less efficiently during 72 h of cytokine treatment. Concomitantly, TNF- impaired induction of endogenous and secreted hCG-ß protein levels in these cultures. The data suggest that TNF- decreases hCG-ß mRNA and protein expression by reducing gene transcription and trophoblast cell fusion. Suppression of these processes by TNF- could partly explain the adverse effects of the cytokine on placental function and pregnancy outcome.
PGE2 up-regulates EGF-like growth factor biosynthesis in human granulosa cells: new insights into the coordination between PGE2 and LH in ovulation
LH and prostaglandin E2 (PGE2) share many similar effects on the pre-ovulatory follicle. They can induce independently cumulus expansion, the resumption of meiosis and progesterone production. However, cyclooxygenase-2 (COX-2) inhibitors were found to hinder most of the LH-induced effects. Recently, EGF-like growth factors amphiregulin (Ar) and epiregulin (Ep) were found to be produced in response to LH stimulation and to induce cumulus expansion and oocyte maturation. We aimed at evaluating whether PGE2 induces Ar and Ep syntheses in human granulosa cells and whether the inhibition of PGE2 production by selective COX-2 inhibitor, nimesulide, affects LH-induced Ar and Ep biosynthesis. Ar and Ep mRNA levels increased following PGE2 stimulation, in a dose- and time-dependent manner, which resembled those of LH. The blockade of protein kinase A (PKA) (by H89) and mitogen-activated protein kinase (MAPK) (by UO126) reduced the expression of PGE2-induced Ar and Ep biosynthesis. Although the stimulation of the cells with LH in the presence of nimesulide did not change the progesterone levels, it resulted in a significant reduction of Ar and Ep biosynthesis. In conclusion, PGE2 may mimic LH action, at least in part, by the induction of Ar and Ep biosynthesis, which involves cAMP/PKA and MAPK pathways. The negative effect of nimesulide on the ovulatory process may be due to the reduction of Ar and Ep biosynthesis, which implies a possible collaborative role between PGE2 and LH on their induction.
<< Home