Global Gene Profiling in Human Endometrium during the Window of Implantation

Abstract

Implantation in humans is a complex process that is temporally and spatially restricted. Over the past decade, using a one-by-one approach, several genes and gene products that may participate in this process have been identified in secretory phase endometrium. Herein, we have investigated global gene expression during the window of implantation (peak E2 and progesterone levels) in well characterized human endometrial biopsies timed to the LH surge, compared with the late proliferative phase (peak E2 level) of the menstrual cycle. Tissues were processed for poly(A(+)) RNA and hybridization of chemically fragmented, biotinylated cRNAs on high density oligonucleotide microarrays, screening for 12,686 genes and expressed sequence tags. After data normalization, mean values were obtained for gene readouts and fold ratios were derived comparing genes up- and down-regulated in the window of implantation vs. the late proliferative phase. Nonparametric testing revealed 156 significantly (P < 0.05) up-regulated genes and 377 significantly down-regulated genes in the implantation window. Up-regulated genes included those for cholesterol trafficking and transport [apolipoprotein (Apo)E being the most induced gene, 100-fold], prostaglandin (PG) biosynthesis (PLA2) and action (PGE2 receptor), proteoglycan synthesis (glucuronyltransferase), secretory proteins [glycodelin, mammaglobin, Dickkopf-1 (Dkk-1, a Wnt inhibitor)], IGF binding protein (IGFBP), and TGF-beta superfamilies, signal transduction, extracellular matrix components (osteopontin, laminin), neurotransmitter synthesis (monoamine oxidase) and receptors (gamma aminobutyric acid A receptor pi subunit), numerous immune modulators, detoxification genes (metallothioneins), and genes involved in water and ion transport [e.g. Clostridia Perfringens Enterotoxin (CPE) 1 receptor (CPE1-R) and K(+) ion channel], among others. Down-regulated genes included intestinal trefoil factor (ITF) [the most repressed gene (50-fold)], matrilysin, members of the G protein-coupled receptor signaling pathway, frizzled-related protein (FrpHE, a Wnt antagonist), transcription factors, TGF-beta signaling pathway members, immune modulators (major histocompatibility complex class II subunits), and other cellular functions. Validation of select genes was conducted by Northern analysis and RT-PCR using RNA from endometrial biopsies obtained in the proliferative phase and the implantation window and by RT-PCR using RNA from cultured endometrial epithelial and stromal cells. These approaches confirmed up-regulation of genes corresponding to IGFBP-1, glycodelin, CPE1-R, Dkk-1, mammaglobin, and ApoD and down-regulation for PR membrane component 1, FrpHE, matrilysin, and ITF, as with the microarray data. Cultured endometrial epithelial cells were found to express mRNAs for glycodelin, CPE-1R, Dkk-1, the gamma aminobutyric acid A receptor pi subunit, mammaglobin, matrilysin, ITF and PR membrane component 1. The expression of IGFBP-1, CPE1-R, Dkk-1, and ApoD mRNAs increased upon decidualization of stromal...

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.…”

“…It was recently found to be specifically up-regulated by progesterone in in vitro decidualized endometrial stromal cells [70], was up-regulated in microarray study of mid-secretory endometrium [62] and downregulated in eutopic endometrium from women with endometriosis [52].…”

“…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.…”

Progesterone blocks estrogen-induced DNA synthesis through the inhibition of replication licensing

“…Thus, there have been several studies that have profiled gene expression patterns in the uterus after sex steroid hormone treatment of ovariectomized mice or of endometrial samples isolated at different stages of the menstrual cycle in humans (24)(25)(26)(27). In general these studies have taken RNA extracted from whole uterine tissue to profile.…”