In humans, embryonic implantation and reproduction depends on the interaction of the embryo with the receptive endometrium. To gain a global molecular understanding of human endometrial receptivity, we compared gene expression profiles of pre-receptive (day LH+2) versus receptive (LH+7) endometria obtained from the same fertile woman (n = 5) in the same menstrual cycle in five independent experiments. Biopsies were analysed using the Affymetrix HG-U95A array, a DNA chip containing approximately 12,000 genes. Using the pre-defined criteria of a fold change >/=3 in at least four out of five women, we identified 211 regulated genes. Of these, 153 were up-regulated at LH+7 versus LH+2, whereas 58 were down-regulated. Amongst these 211 regulated genes, we identified genes that were known to play a role in the development of a receptive endometrium, and genes for which a role in endometrial receptivity, or even endometrial expression, has not been previously described. Validation of array data was accomplished by mRNA quantification by real time quantitative fluorescent PCR (Q-PCR) of three up-regulated [glutathione peroxidase 3 (GPx-3), claudin 4 (claudin-4) and solute carrier family 1 member 1 (SLC1A1)] genes in independent LH+2 versus LH+7 endometrial samples from fertile women (n = 3) and the three up-regulated genes throughout the menstrual cycle (n = 15). Human claudin-4 peaks specifically during the implantation window, whereas GPx-3 and SLC1A1 showed highest expression in the late secretory phase. In-situ hybridization (ISH) experiments showed that GPx-3 and SLC1A1 expression was restricted to glandular and luminal epithelial cells during the mid- and late luteal phase. The present work adds new and important data in this field, and highlights the complexity of studying endometrial receptivity even using global gene-expression analysis.

Synaptonemal complexes (SCs) are structures that are formed between homologous chromosomes during meiotic prophase. They are probably involved in chromosome pairing and recombination. Using a monoclonal anti‐SC antibody we isolated cDNAs encoding a major component of SCs which is localized specifically in synapsed segments of meiotic prophase chromosomes. The protein predicted from the nucleotide sequence of a full‐length cDNA, named SCP1, consists of 946 amino acid residues and has a molecular weight of 111 kDa. It shares several features with nuclear lamins and some recently identified nuclear matrix proteins. The major part of SCP1 consists of long stretches capable of forming amphipathic alpha‐helices. This region shows amino acid sequence similarity to the coiled‐coil region of myosin heavy chain. A leucine zipper is included in this region. The carboxy‐terminus has two small basic domains and several S/T‐P‐X‐X motifs, which are characteristic of DNA‐binding proteins. One of these motifs is a potential target site for p34cdc2 protein kinase. The amino‐terminus is acidic and relatively proline‐rich, but does not contain the S/T‐P‐X‐X motif. The transcription of the gene encoding SCP1 is restricted to zygotene‐diplotene spermatocytes. A polyclonal antiserum raised against the fusion protein of one of the cDNA clones recognizes a single protein on Western blots of isolated SCs, with an electrophoretic mobility identical to that of the antigen recognized by the original monoclonal antibody (mAb), IX5B2. From a detailed comparison of the immunogold labelling of rat SCs by mAb IX5B2 and the polyclonal anti‐fusion protein antiserum respectively, we tentatively infer that the carboxy‐terminus of SCP1 is orientated towards the lateral elements and that the other domains of the protein extend towards the central region between the lateral elements. We conclude that SCP1 is the major component of the transverse filaments of SCs, and speculate that it has evolved by specialization of a nuclear matrix protein.

Controlled ovarian hyperstimulation (COH) used in IVF produces lower implantation rates per embryo transferred compared to natural cycles utilized in ovum donation, suggesting a suboptimal endometrial development. Endometrial receptivity has recently been investigated in natural menstrual cycles with the aid of microarray technology. The aim of this study is to investigate the impact of COH using urinary gonadotrophins with a long protocol with GnRH agonists without progesterone supplementation (similar to the natural cycle) on endometrial gene expression profiles during the window of implantation by comparing the profiles at day hCG + 7 of COH versus LH + 7 of a previous natural cycle in the same women. For this purpose we have used microarray technology by Affymetrix (GeneChip HG_U133A), which allows more than 22,000 genes to be tested simultaneously. Results were validated by semi-quantitative PCR and quantitative PCR experiments. We found that more than 200 genes showed a differential expression of more than 3-fold when COH and normal cycles were compared at hCG + 7 versus LH + 7. We simultaneously re-analysed the LH + 2 versus LH + 7 endometrial gene expression profiles in previous natural cycles in the same subject using this specific GeneChip, the results obtained were consistent with our own published results. This is the first time that gene expression profiles of the endometrium during COH are reported. The large degree of gene expression disturbance is surprising and highlights the need for further efforts to optimize COH protocols.

Successful implantation absolutely depends on the reciprocal interaction between the implantation-competent blastocyst and the receptive uterus. Expression and gene targeting studies have shown that leukemia inhibitory factor (LIF), a cytokine of the IL-6 family, and Hoxa-10, an abdominalB-like homeobox gene, are crucial to implantation and decidualization in mice. Using these mutant mice, we sought to determine the importance of Msx-1 (another homeobox gene formerly known as Hox-7.1) and of Wnt4 (a ligand of the Wnt family) signaling in implantation because of their reported functions during development. We observed that Msx-1, Wnt4, and a Wnt antagonist sFRP4 are differentially expressed in the mouse uterus during the periimplantation period, suggesting their role in implantation. In addition, we observed an aberrant uterine expression of Msx-1 and sFRP4 in Lif mutant mice, and of Wnt4 and sFRP4 in Hoxa-10 mutant mice, further reinforcing the importance of these signaling pathways in implantation. Collectively, the present results provide evidence for a novel cytokine-homeotic-Wnt signaling network in implantation.

No abstract

No relevant alteration was observed in the endometrial development in the early and mid-luteal phases in women undergoing controlled ovarian stimulation for oocyte donation following daily treatment with a standard- or high-dose GnRH antagonist. In addition, the endometrial development after GnRH antagonist mimics the natural endometrium more closely than after GnRH agonist.

We h ave iso la ted th e hum an PEG U M EST gene and have in v estig a ted its im p rin tin g sta tu s and parentalspecific m eth ylation . FISH m apping assign ed th e gene to chrom osom e 7q32, an d h om ologou s sequences w ere id en tified on th e sh ort arm o f hum an chrom osom es 3 and 5. T hrough th e u se o f a n ew ly id en tified in tragen ic polymorphism, exp ression analysis revealed that PEGU M E ST is m o n o a llelica lly tran scrib ed in all feta l tissu es exam ined. In tw o in form ative cases, exp ression w as show n to b e confined to th e p a tern a lly derived allele. In con trast to th e m on oallelic ex p ressio n observed in fetal tissu es, b ia llelic ex p ressio n w as evid en t in adult blood lym phocytes. B ia lle lic ex p ressio n in blood is supported by th e d em on stration of PEG1IM EST tran scripts in a lym p h ob lastoid cell lin e w ith m aternal u n i parental disom y 7. The hum an PEG U M EST gen e spans a genom ic region o f ap p roxim ately 13 kb. Sequence analysis o f th e 5' reg io n o f P E G 1/M EST revealed the existen ce o f a 620-bp-long CpG isla n d that exten d s from th e p u ta tiv e p rom oter reg io n in to in tron 1. We dem onstrate th at th is CpG isla n d is m eth ylated in a parent-of-origin-specific m anner. A ll M sp V H p a ll sites w ere unm ethyl ate d on th e a ctiv e patern al a llele but m ethylated on th e in a c tiv e m aternal one.

The hum an in su lin -lik e grow th factor type 2 recep tor gen e (IGF2R) is b ia llelica lly expressed in a variety o f fetal and adult tissu es. In contrast, the im printed m ouse Igf2r gen e is exp ressed exclu sively from the ma ternally in h erited chrom osom e. The m ouse gene con tains tw o CpG isla n d s th at are m ethylated in a parentspecific m anner. M éthylation o f th e CpG island in the prom oter region occu rs on th e repressed paternal gene copy. M éthylation of th e CpG island in intron 2 is specific for th e a ctiv e m aternal allele and m ay repre sen t the prim ary im print. H ere, we have analyzed the hum an IGF2R gen e to in v estig a te w hether these m otifs and th eir parent-of-origin-specific epigenetic modifi cation have b een conserved. As in th e mouse, the hu man IGF2R gen e w as found to contain two CpG is lands, one en com p assin g th e transcription start site (CpG 1) and th e oth er in th e second intron (CpG 2). CpG 2 is h yp erm eth ylated on th e m aternal IGF2R al lele. In contrast to th e situ a tio n in th e m ouse, how ever, the hum an CpG 1 is com p letely unm ethylated on both parental chrom osom es, The hum an and m ouse intronic CpG islan d s la ck sign ifican t sequence hom ol ogy* w h ich su g g ests th a t DNA conform ation plays a role in allele-Specific m éthylation.