Abstract
During implantation, the uterine stromal cells undergo terminal differentiation into decidual cells, which support the proper progression of maternal-embryo interactions to successful establishment of pregnancy. The decidual cells synthesize extracellular matrix (ECM) components, such as laminins and collagens, which assemble into a unique basal lamina-like network that surrounds these cells. The functional significance of this matrix during implantation is unknown. We previously showed that the transcription factor CCAAT enhancer-binding protein β (C/EBPβ) critically regulates decidualization in the mouse. We now provide evidence that C/EBPβ directly controls the Lamc1 gene, which encodes a predominant laminin constituent of the ECM produced by the decidual cells. Suppression of Lamc1 expression in mouse primary endometrial stromal cells prevented the assembly of this ECM and impaired stromal differentiation. Attenuation of expression of integrin β1, a major constituent of the integrin receptors targeted by decidual laminins, also inhibited this differentiation process. Disruption of laminin-integrin interactions led to impaired activation of the focal adhesion kinase, an integrin-mediated regulator of cytoskeletal remodeling during decidualization. To further analyze the role of the decidual ECM in modulating maternal-embryo interactions, we monitored trophoblast invasion into differentiating uterine stromal monolayers, using a co-culture system. Silencing of stromal Lamc1 expression, which prevented formation of the basal lamina-like matrix, resulted in marked reduction in trophoblast outgrowth. Collectively, our findings identified C/EBPβ as a critical regulator of the unique ECM that controls decidual cell architecture and differentiation, and it provided new insights into the mechanisms by which the uterine stromal microenvironment controls the progression of embryo implantation.
Highlights
Expression of Laminin Subunits during Decidualization Is Regulated by C/EBP in Vivo—To identify C/EBP-regulated pathways controlling stromal differentiation and remodeling during decidualization, we used DNA microarray analysis to compare the uterine mRNA expression profiles of mouse endometrial stromal cells (MESC) isolated from WT and C/EBP-null uteri at 24 h following initiation of decidualization as described under “Experimental Procedures.”
We identified several hundred genes whose expression was altered significantly in C/EBP-null uteri compared with WT uteri
We validated these findings by assessing the Lamc1 and Lama1 mRNA levels in WT and CCAAT enhancer-binding protein  (C/EBP)null MESC using real time PCR analysis. The expression of both Lamc1 and Lama1 mRNAs was markedly reduced in C/EBP-null MESC relative to WT cells, whereas the levels of progesterone receptor (PR) mRNA did not alter significantly. These results revealed that C/EBP is a regulator of the constituents of the stromal basal lamina-like extracellular matrix (ECM) during decidualization
Summary
E, estrogen; P, progesterone; C/EBP, CCAAT enhancer-binding protein ; PRP, prolactin-related protein; ALP, alkaline phosphatase; ECM, extracellular matrix; FAK, focal adhesion kinase; MESC, mouse endometrial stromal cells; MEF, mouse embryonic fibroblast; PR, progesterone receptor; ER, estrogen receptor; Ad-DN, adenovirus expressing dominant negative; Ad-CTRL, control adenovirus. Using a DNA microarray approach, we analyzed uterine stromal cells isolated from wild-type (WT) and C/EBP-null mice to identify candidate downstream targets of C/EBP during the decidualization process Prominent among these targets were the Lama and Lamc genes encoding the laminin subunits ␣1 and ␥1, respectively, which are well known components of the stromal ECM generated during decidualization. These findings suggested that C/EBP-regulated pathways play an important role in the formation of the basal lamina-like ECM during decidualization. We evaluated the role of laminins in facilitating cross-talk between endometrial cells and the embryo To study these interactions, we designed a co-culture system in which pre-implantation mouse blastocysts are allowed to attach to and invade a monolayer of differentiating MESC. We directly tested and showed that ECM containing laminin ␥1 is critical for proper progression of stromal differentiation and cytoskeletal remodeling, which in turn control embryo invasion into the stromal compartment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
