Human endometrial stromal cell-trophoblast interactions: mutual stimulation of chemotactic migration and promigratory roles of cell surface molecules CD82 and CEACAM1.

We have previously shown that the presence of trophoblast cells enhances invasiveness of decidualizing human endometrial stromal cells. The metastasis suppressor CD82, which has antimigratory function in tumor cells, is up-regulated in decidualizing endometrial stromal cells. CEACAM1 is expressed in trophoblast cells at the invasion front in early placenta and is considered proinvasive. Here, we investigate the role of CD82 and CEACAM1 in cocultures of the endometrial stromal cell line T-HESC and AC-1M88 trophoblast cells. In transwell migration assays, chemotaxis of AC-1M88 cells was stimulated by coplated T-HESC in the lower compartment or by the combination of heparin-binding EGF-like growth factor (HB-EGF), interleukin-1 beta (IL-1beta), and leukemia inhibitory factor (LIF), local factors present at the time of implantation. In an implantation model of AC-1M88 trophoblast spheroids on a monolayer of T-HESC, spheroid expansion was enhanced in the presence of HB-EGF/IL-1beta/LIF. Silencing of CEACAM1 in AC-1M88 blunted this response. Chemotactic migration of T-HESC was stimulated by trophoblast secretions or HB-EGF/IL-1beta/LIF. These responses were suppressed by CD82 depletion in T-HESC. Proteome profiling revealed the presence of platelet-derived growth factor (PDGF)-AA in trophoblast supernatant. Chemotaxis of T-HESC toward PDGF-AA was significantly inhibited by CD82 silencing. Neutralization of PDGF-AA in AC-1M88 conditioned media reduced the chemotactic effect on T-HESC. In summary, we demonstrate a mutual stimulation of chemotactic migration between trophoblast and endometrial stromal cells and promigratory roles for the cell surface molecules CEACAM1 and CD82, which may serve to support tissue remodeling at the implantation site.

Control of human endometrial stromal cell motility by PDGF-BB, HB-EGF and trophoblast-secreted factors.

Human implantation involves extensive tissue remodeling at the fetal-maternal interface. It is becoming increasingly evident that not only trophoblast, but also decidualizing endometrial stromal cells are inherently motile and invasive, and likely contribute to the highly dynamic processes at the implantation site. The present study was undertaken to further characterize the mechanisms involved in the regulation of endometrial stromal cell motility and to identify trophoblast-derived factors that modulate migration. Among local growth factors known to be present at the time of implantation, heparin-binding epidermal growth factor-like growth factor (HB-EGF) triggered chemotaxis (directed locomotion), whereas platelet-derived growth factor (PDGF)-BB elicited both chemotaxis and chemokinesis (non-directed locomotion) of endometrial stromal cells. Supernatants of the trophoblast cell line AC-1M88 and of first trimester villous explant cultures stimulated chemotaxis but not chemokinesis. Proteome profiling for cytokines and angiogenesis factors revealed neither PDGF-BB nor HB-EGF in conditioned media from trophoblast cells or villous explants, while placental growth factor, vascular endothelial growth factor and PDGF-AA were identified as prominent secretory products. Among these, only PDGF-AA triggered endometrial stromal cell chemotaxis. Neutralization of PDGF-AA in trophoblast conditioned media, however, did not diminish chemoattractant activity, suggesting the presence of additional trophoblast-derived chemotactic factors. Pathway inhibitor studies revealed ERK1/2, PI3 kinase/Akt and p38 signaling as relevant for chemotactic motility, whereas chemokinesis depended primarily on PI3 kinase/Akt activation. Both chemotaxis and chemokinesis were stimulated upon inhibition of Rho-associated, coiled-coil containing protein kinase. The chemotactic response to trophoblast secretions was not blunted by inhibition of isolated signaling cascades, indicating activation of overlapping pathways in trophoblast-endometrial communication. In conclusion, trophoblast signals attract endometrial stromal cells, while PDGF-BB and HB-EGF, although not identified as trophoblast-derived, are local growth factors that may serve to fine-tune directed and non-directed migration at the implantation site.

Expression of distinct RNAs from 3' untranslated regions.

The 3' untranslated regions (3'UTRs) of eukaryotic genes regulate mRNA stability, localization and translation. Here, we present evidence that large numbers of 3'UTRs in human, mouse and fly are also expressed separately from the associated protein-coding sequences to which they are normally linked, likely by post-transcriptional cleavage. Analysis of CAGE (capped analysis of gene expression), SAGE (serial analysis of gene expression) and cDNA libraries, as well as microarray expression profiles, demonstrate that the independent expression of 3'UTRs is a regulated and conserved genome-wide phenomenon. We characterize the expression of several 3'UTR-derived RNAs (uaRNAs) in detail in mouse embryos, showing by in situ hybridization that these transcripts are expressed in a cell- and subcellular-specific manner. Our results suggest that 3'UTR sequences can function not only in cis to regulate protein expression, but also intrinsically and independently in trans, likely as noncoding RNAs, a conclusion supported by a number of previous genetic studies. Our findings suggest novel functions for 3'UTRs, as well as caution in the use of 3'UTR sequence probes to analyze gene expression.