Gene expression profiling of human endometrial receptivity on days LH+2 versus LH+7 by microarray technology

Abstract

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.

Uterine receptivity to human embryonic implantation: Histology, biomarkers, and transcriptomics

“…However, caveats include reactive inflammatory changes and subsequent gene alterations as a result of the first biopsy [56], and different microenvironments and/or complement of cell types may be represented in the two biopsies from the same subject. Figure 1 represents the distribution of significantly changed genes among different groups of genes in the studies by Kao et al [52], Carson et al [53], Borthwick et al [55], Riesewijk et al [54] and Mirkin et al [56]. Genes with unknown biological function represented one of the biggest groups of regulated genes.…”

“…Five studies were published, within a short time frame, reporting the transcriptome human endometrium during the window of implantation [52][53][54][55][56] (Table 1). Remarkably, all studies used the same microarray platform to perform their analysis.…”

“…Two studies [53,55] pooled RNA from different patients to run on microarrays. Four out of five studies [52,53,55,56] used pre-defined fold change cut off of 2.0 as evidence of change in gene regulation, while Riesewijk et al [54] used a more stringent approach and a 3.0 fold change as a cutoff. The latter study is the only one that analyzed samples from the same woman in the early and the mid-secretory phase of the menstrual cycle.…”

“…The main difference between the studies comes from the analysis of functionally and structurally different stages of the menstrual cycle (proliferative and secretory), which is reflected by the large variability of the up-and down-regulated genes. Interestingly, however, as noted above, Riesewijk et al [54] performed microarray analysis of endometrium from the same women at LH+2 and at LH+7, which minimizes inter-patient variability. However, caveats include reactive inflammatory changes and subsequent gene alterations as a result of the first biopsy [56], and different microenvironments and/or complement of cell types may be represented in the two biopsies from the same subject.…”

2 Identification of Genes Induced by the Conceptus in the Bovine Endometrium During the Pre-Implantation Period

“…In humans several studies using commercially available microarrays were done investigating gene expression changes occurring in the endometrium during the menstrual cycle. In two studies, the proliferative phase of the menstrual cycle was compared with the phase coincident with the "window of implantation" (Kao et al, 2002;Carson et al, 2002) and in another three studies gene expression differences between the early secretory phase (2-4 days after the LH-surge) and mid-luteal phase (days 7-9 after the LH-surge) were analyzed (Martin et al, 2002;Riesewijk et al, 2003;Borthwick et al, 2003). Endometrial gene expression of the proliferative phase versus the secretory phase of the sexual cycle was also compared in the rhesus monkey (Ace and Okulicz, 2004) and in the mouse (Tan et al, 2003).…”