Expression and function of matrix metalloproteinases and their inhibitors at the maternal-embryonic boundary during mouse embryo implantation

Serglycin proteoglycan synthesis in the murine uterine decidua and early embryo

This study has explored the localization and synthesis of the serglycin proteoglycan in the murine embryo and uterine decidua during midgestation. Embryos in deciduae were subjected to in situ hybridization with cRNA probes and to immunohistochemical detection with a specific antibody against murine serglycin. Adherent decidual cell cultures were prepared from freshly isolated deciduae. Proteoglycan biosynthesis was investigated by labeling intact deciduae and decidual cultures with (35)S-sulfate. Serglycin mRNA was detected by in situ hybridization throughout the mesometrial portion and at the periphery of the antimesometrial portion of the decidua at Embryonic Day (E) 8.5, and in the parietal endoderm surrounding the embryo. Serglycin mRNA was detected in fetal liver at E11.5-E14.5. Serglycin was detected by immunohistochemistry in decidua and parietal endoderm at E8.5 and in liver at E13.5. Most of the proteoglycans synthesized by cultured intact deciduae (78%) and adherent decidual cultures (91%) were secreted into the medium. Serglycin proteoglycan may play an important role in uterine decidual function during early postimplantation development.

Tissue inhibitor of matrix metalloproteinase-3 expression in the mouse uterus during implantation and artificially induced decidualization

During implantation in mice, tissue inhibitor of matrix metalloproteinases-3 is believed to play a key role in inhibiting matrix metalloproteinase activity associated with embryo invasion and tissue remodeling. The first objective of this study was to quantitatively compare the steady-state mRNA levels of tissue inhibitors of matrix metalloproteinases between segments of the mouse uterus undergoing decidualization compared to those that are not during early pregnancy plus oil-induced decidualization. Steady-state tissue inhibitor of metalloproteinase-3 mRNA levels were significantly greater in implantation compared to interimplantation areas on days 6 and 7 of pregnancy and in stimulated compared to nonstimulated uterine horns at 48 and 72 hr after artificial induction of decidualization. Steady-state tissue inhibitor of metalloproteinase-1 mRNA levels were significantly greater in implantation compared to interimplantation areas on days 5-8 of pregnancy and in stimulated compared to nonstimulated uterine horns at 24, 48, and 72 hr after oil stimulation. Therefore, the steady-state mRNA levels of tissue inhibitors of metalloproteinase-1 and -3 increased in the uterus during decidualization. The second objective of this study was to determine if transforming growth factor-beta1 influences tissue inhibitors of metalloproteinase mRNA concentrations in mouse endometrial stromal cells. As determined by Northern blot analyses, transforming growth factor beta1 significantly increased tissue inhibitors of matrix metalloproteinases-1 and -3 mRNA levels in cultured mouse endometrial stromal cells isolated from uteri sensitized for decidualization. On the other hand, interleukin-1, epidermal growth factor, and leukemia inhibitory factor had no effect. The results of this study further characterize the tissue inhibitor of metalloproteinase expression in the uterus during implantation and artificially induced decidualization and the potential control of their expression in the stroma by transforming growth factor.

Acute food restriction increases collagen breakdown and phagocytosis by mature decidual cells of mice

An ultrastructural study was undertaken on antimesometrial mature decidual tissue of fed and food-restricted mice, on day 9 of pregnancy. The mean ad libitum food intake was established on mice from the 8th till the 9th day of pregnancy. Fed mice were used as controls. Experimental animals were divided into two groups: one was allowed to feed 25% of normal diet and the other 50%. Extracellular collagen fibrils were scarce in fed animals and conspicuous in food restriction. Granular electron-dense deposits and filamentous aggregates of disintegrating collagen fibrils were observed in all food-deprived mice but were rarely noted in fed animals. Intracellular vacuolar structures exhibited other typical cross-banded collagen immersed in finely granular electron-translucent material (clear vacuole) or electron-dense material containing collagen fibrils with a faint periodicity (dark vacuole). The clear and dark vacuoles were scarce in fed animals and evident in food-restricted mice, mainly in those 25% food restricted. Although collagen breakdown may be part of the normal process of decidual tissue remodelling our results suggest that it is enhanced in food-restricted animals. Thus it seems that collagen breakdown is a normal mechanism that may be regulated by the food intake of the pregnant animal.

Genes governing placental development

The placenta is essential for fetal growth because it promotes the delivery of nutrients and oxygen from the maternal circulation. In mice, many gene mutations disrupt formation of the placenta, with specific effects at different times and on different components. Studies of these mutations are beginning to provide insights into both the molecular pathways required for formation of different placental substructures and the nature of intercellular interactions, between trophoblast, mesenchymal and vascular components, that regulate placental development. Conserved gene expression patterns in humans should enable the elucidation of the molecular basis of human placental dysfunction.

A mechanistic assessment of 1,3-butadiene diepoxide-induced inhibition of uterine deciduoma proliferation in pseudopregnant rats

Butadiene diepoxide (BDE), a reactive metabolite of 1,3-butadiene that is an important industrial chemical used in synthetic rubber production causes a dose-dependent inhibition of deciduoma development in pseudopregnant Sprague-Dawley rats. This study used 4 daily i.p. BDE doses of 0.20, 0.25, 0.30, 0.35, or 0.40 to characterize mechanisms that may be responsible for the antideciduoma effect. Pseudopregnant rats were treated either before (pseudopregnancy [PPG] days 1-4) or after (PPG days 5-9) deciduoma induction by endometrial trauma with a blunt needle. Animals were killed on PPG day 9 and evaluated for serum progesterone and endometrial protein and DNA. RT-PCR was used to measure message for estrogen receptor (ER) alpha and pituitary adenylate cyclase-activating polypeptide (PACAP). Substrate zymography and Western blotting were used respectively to measure matrix metalloproteinase (MMP)-9 and inducible nitric oxide synthase. The antideciduoma effects of BDE were associated with decreases in endometrial weight, protein, and DNA, with decreases in serum progesterone, and with decreases in PACAP message and MMP-9. A reduction in NOS was identified at the highest dose of BDE. Message for estrogen receptor (ER) alpha was not affected at any dose. We conclude that the reduction in decidual proliferation was direct and appeared to be associated with either 1) a decrease in the effectiveness of the deciduogenic stimulation and/or a weakened endometrial sensitivity to the stimulus; or 2) an effect on deciduoma development. Molecular mechanisms that apparently contributed to BDE inhibition of decidual metabolism included the synthesis of protein and DNA involved in decidual growth, the synthesis and activation of a matrix metalloproteinase for degradation of the extracellular matrix that is essential for tissue remodeling during deciduoma development, and the nitric oxide/nitric oxide synthase and pituitary adenylate cyclase-activating peptide systems that are involved in promoting vasodilation and increased vascular permeability to enhance the availability of substrates for maximal deciduoma growth. The ovotoxicity of BDE, which has previously been established, may indirectly affect decidual proliferation by reducing progesterone, the preeminent endocrine regulator of deciduoma development. The findings also suggest that BDE may possess no estrogenic action since it was associated with endometrial weight loss and unaltered levels of the estrogen receptor alpha mRNA expression.

Basigin (murine EMMPRIN) stimulates matrix metalloproteinase production by fibroblasts

Analysis of basigin-null mice has shown that basigin is involved in several important physiological processes including reproductive, immune, and neural activities (Igakura et al., 1998, Dev Biol 194:152-165). However, its molecular mechanism of action in these processes has not yet been established. Our objective here is to determine whether basigin has functional properties similar to its apparent human tumor cell homolog, EMMPRIN, i.e., the ability to stimulate matrix metalloproteinase (MMP) production in fibroblasts (Guo et al. 1997, J Biol Chem 272:24-27). Mouse cells express two major forms of basigin that differ in their degree of glycosylation (molecular weights: 45 and 58 kDa) but, in similar fashion to human EMMPRIN, mouse tumor cells express higher levels of basigin than normal cells. We have used three different methods to show that basigin stimulates MMP expression in fibroblasts. First, recombinant basigin was partially purified from transfected CHO cells by affinity chromatography. This basigin preparation stimulates production of MMPs on addition to fibroblasts in culture. Second, co-culture of basigin-transfected CHO cells with fibroblasts gives rise to increased expression of MMPs as compared to control co-cultures. Third, we employed a novel approach in which a recombinant basigin adenovirus was constructed and used to infect the target fibroblasts, so that mutual stimulation between neighboring fibroblasts would be expected to result. In this method also, basigin stimulates production of MMPs. Finally, we showed that addition of basigin or EMMPRIN antibody, respectively, to recombinant basigin or EMMPRIN adenovirus-infected cells augments stimulation of MMP synthesis, implying that cross-linking of basigin/EMMPRIN in the membrane enhances activity. We conclude that murine basigin and human EMMPRIN have similar MMP-inducing activities and are functional homologs.

Trophoblast giant-cell differentiation involves changes in cytoskeleton and cell motility

Trophoblast giant-cell differentiation is well-characterized at the molecular level, yet very little is known about how molecular changes affect the cellular functions of trophoblast in embryo implantation. We have found, using both explanted E7.5 mouse embryo ectoplacental cone and the rat choriocarcinoma (Rcho-1) cell line, that trophoblast differentiation is distinguished by dramatic changes in cytoarchitecture and cell behavior. Undifferentiated trophoblast cells contain little organized actin and few small, peripheral focal complexes and exhibit high membrane protrusive activity, while differentiated trophoblast giant cells contain prominent stress fibers, large internal as well as peripheral focal adhesions, and become immotile. The dramatic changes in cell behavior and cytoskeletal organization of giant cells correlate with changes in the activities of the Rho family of small GTPases and a decrease in tyrosine phosphorylation of focal adhesion kinase. Together, these data provide detailed insight into the cellular properties of trophoblast giant cells and suggest that giant-cell differentiation is characterized by a transition from a motile to a specialized epithelial phenotype. Furthermore, our data support a phagocytic erosion, rather than a migratory infiltration, mechanism for trophoblast giant-cell invasion of the uterine stroma.

Coexpression of cytokeratin and vimentin in mice trophoblastic giant cells

Trophoblastic giant cells reach their maximum size and exhibit a conspicuous synthetic and invasive activity during mouse placentation. The cytoskeleton, given the complex functions of the cells, shows a well-developed network of intermediate filament proteins. Immunohistochemistry combined with confocal and conventional immunofluorescence studies of intermediate filaments proteins cytokeratin and vimentin were performed in mice trophoblastic giant cells on days 9-11 of pregnancy. Specimens were fixed in phosphate-buffered formaldehyde and tissues were processed for routine paraffin embedding. Trophoblastic giant cells from antimesometrial, lateral or mesometrial uterine regions, through days 9-11 of pregnancy, expressed the same staining with both immunoperoxidase and immunofluorescent techniques. Cytokeratin filamentous structures were intensely immunoreactive and were detected throughout the cells cytoplasm; a few cells exhibited strongest fluorescence in the peripheral cytoplasm. Vimentin-positive staining was often distributed throughout the cells cytoplasm, most frequently and more intensely in the peripheral region; in some cells, it was present only in the peripheral regions. It is probable that expression of vimentin in midpregnancy trophoblastic giant cells may be associated with the rapid and conspicuous increase in size and synthetic activity of the cells and also with phagocytosis of degraded materials and invasion of decidual tissue.

Do matrix metalloproteinases MMP-2 and MMP-9 (gelatinases) play a role in renal development, physiology and glomerular diseases?

Metalloproteinases MMP-2 and MMP-9 (also called gelatinases) are involved in cell invasion and in embryonic development and organogenesis. A growing number of reports suggest that MMP-2 and MMP-9 play some role in renal development, renal tubule physiology and glomerular pathophysiology. This editorial will focus on recent controversial data, especially those obtained from studies on MMP-9-deficient mice, which shed new light on the functions of gelatinases in normal and diseased kidneys.

Inflammation dampened by gelatinase A cleavage of monocyte chemoattractant protein-3

Tissue degradation by the matrix metalloproteinase gelatinase A is pivotal to inflammation and metastases. Recognizing the catalytic importance of substrate-binding exosites outside the catalytic domain, we screened for extracellular substrates using the gelatinase A hemopexin domain as bait in the yeast two-hybrid system. Monocyte chemoattractant protein-3 (MCP-3) was identified as a physiological substrate of gelatinase A. Cleaved MCP-3 binds to CC-chemokine receptors-1, -2, and -3, but no longer induces calcium fluxes or promotes chemotaxis, and instead acts as a general chemokine antagonist that dampens inflammation. This suggests that matrix metalloproteinases are both effectors and regulators of the inflammatory response.

Molecular genetics of implantation in the mouse

Embryo implantation is a complex developmental process requiring precise coordination between mother and offspring to ensure success. Implantation failure is clinically relevant to in vitro fertilization programs and to an understanding of diseases of pregnancy like preeclampsia. Basic and clinical research have identified a number of proteins involved in peri-implantation development, but an understanding of the implantation process and its cellular and molecular components is just beginning. This review will focus on the implantation and development of the murine embryo and placenta. The significance of ectopic expression and targeted mutagenesis models to these processes will be discussed.

Tissue inhibitor of metalloproteinase-3 expression is upregulated during human cytotrophoblast invasion in vitro

Surprisingly, a successful human pregnancy requires cells from the fetal portion of the placenta (cytotrophoblasts) to adopt tumor-like properties. Cytotrophoblasts attach the conceptus to the endometrium by invading the uterus, and they initiate blood flow to the placenta by breaching maternal vessels. But unlike tumor metastasis, cytotrophoblast invasion is highly regulated both spatially and temporally. Our previous work showed that matrix metalloproteinase-9 (MMP-9) expression is upregulated during cytotrophoblast differentiation along the invasive pathway, and that activity of this proteinase specifies the cells' ability to degrade extracellular matrix (ECM) substrates in vitro. Here we tested the hypothesis that invading cytotrophoblasts express an unusual tissue inhibitor of metalloproteinase (TIMP) repertoire that allows them to regulate their MMP-9 proteolytic activity. By using protease-substrate gel electrophoresis, we found that human cytotrophoblasts express primarily TIMP-3. We showed that the cells' TIMP-3 expression is regulated in accord with that of MMP-9. The highest levels of protein and mRNA for both these molecules were detected after differentiation to a fully invasive phenotype and during early gestation, when invasion peaks, rather than at term, when invasion has stopped. Our results suggest that coexpression of MMP-9 and TIMP-3 by invading cytotrophoblasts plays an important role in regulating the depth of uterine invasion.

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the mouse uterus during the peri-implantation period

The attachment of the blastocyst to the uterine luminal epithelium and the subsequent invasion by trophoblast cells through the stroma and deciduum occur in a highly regulated manner by remodeling of the extracellular matrix. We investigated the temporal and spatial expression of mRNAs for four matrix metalloproteinases (MMPs; MMP-2 [gelatinase A], MMP-3 [stromelysin 1], MMPs; MMP-2 [gelatinase B], and MMP-13 [collagenase 3]) and tissue inhibitors of metalloproteinases (TIMPs; TIMP-1, TIMP-2, and TIMP-3) in the mouse uterus from days 1 to 8 of pregnancy. Northern blot analyses showed the transcripts for MMP-2, MMP-3, RNA on these days. However, MMP-13 mRNA was not detected in the uterus, and only weak signals for MMP-3 mRNA were detected in the myometrium. Striking expression was observed with MMP-2 mRNA in the subepithelial stroma on days 3-5. With the progression of decidualization on day 6, signals were primarily in the secondary decidual zone. On day 8, MMP-2 mRNA was localized at the site of placenta formation in the mesometrial pole. Signals for MMP-9 mRNA were first detected in a small population of stromal cells exclusively at the site of implantation on day 5 at the antimesometrial pole. However, the most pronounced expressed was noted in trophoblast giant cells on day 8. TIMP-1 mRNA was present in the myometrium on day 1. On days 2-5, modest signals were detected in the stroma, and on days 6 and 8, they were in the secondary decidual zone. Localization of TIMP-2 mRNA was similar to that of TIMP-1 except it was restricted to the stroma on day 1. The regulation of TIMP-3 was more pronounced. While a gradual increase in signals was observed in stromal cells from days 1 to 4, strong signals were detected in antimesometrial stromal cells at the sites of blastocyst attachment on day 5. On days 6 and 7, even stronger signals were present in the primary decidual zone surrounding the embryo, and on day 8 signals were localized primarily in the mesometrial decidual bed. These results suggest that MMP-2 may participate in the early phase of decidualization and neovascularization required for placentation. The restricted MMP-9 expression in stromal cells on day 5 and in trophoblast giant cells on day 8, coupled with the expression of TIMP-3 in the stroma surrounding the embryo, suggests that a fine balance between MMP-9 and TIMP-3 may regulate trophoblast invasion in the uterus.

Expression pattern of the epithelial v-like antigen (Eva) transcript suggests a possible role in placental morphogenesis

Adhesive mechanisms are considered to be of crucial importance for blastocyst adherence to the uterine wall, as well as for the interactions between embryonal and decidual tissues during hemochorial placenta formation. Epithelial V-like Antigen (Eva) is a novel homophilic adhesion molecule of the immunoglobulin superfamily, which during mouse embryonic development is expressed by various differentiating epithelia. In the present paper we describe Eva expression during mouse trophoblast invasion and placental morphogenesis, analysing day 5.5 to 18.5 postcoitum (p.c.) placentas and deciduomas by in situ hybridization. Eva transcripts were detected in spongiotrophoblast cells from 7.5 to 18.5 days p.c. Expression was uniform at early stages, but after day 11.5, p.c. became limited to the invasive subpopulation of spongiotrophoblasts (known as glycogen cells). Trophoblast giant cells did not express Eva in any of the stages analysed. Besides trophoblasts, also early postimplantation decidua was positive for Eva transcripts. In decidual tissue, Eva expression was present at day 5.5 p.c., peaked at day 7.5 p.c., and declined on successive days. The expression pattern of Eva transcripts suggests that during mouse placenta formation, its protein product may play a role in the processes of trophoblast invasion, decidual response, and trophoblast-decidual interaction.

Trophoblast giant cells express NF-kappa B2 during early mouse development

To investigate whether transcription factors of the NF-kappa B family could play a role in early mammalian development, we have analyzed the expression of nfkb1, nfkb2, c-Rel, RelA, RelB, and bcl-3 from 6.5- to 10.5-day mouse embryo implantation sites. Our study shows that nfkb2 mRNA and protein are specifically localized in trophoblast giant cells throughout the stages analyzed. Trophoblast giant cells obtained upon in vitro cultures of 7.5-day ectoplacental cones display NF-kappa B DNA-binding activity that is supershifted by the anti-NF-kappa B2 antibody. Trophoblast giant cells are embryo-derived cells that form an interface between embryonic and maternal tissues during early mouse development; they are involved in decidual remodeling and expansion of the embryonic cavity, placenta formation, and possibly avoidance of maternal immune response to the embryo. Our study suggests that NF-kappa B2 could play a role in the modulation of genes expressed in trophoblast giant cells during the course of early embryogenesis, and therefore be relevant for tissue remodeling and morphogenesis of placenta.

Murine subtilisin-like proteinase SPC6 is expressed during embryonic implantation, somitogenesis, and skeletal formation

During mammalian embryogenesis, proteinases are important for both matrix remodeling and the activation of latent growth factors. As subtilisin-like prohormone convertases (SPCs) have recently been found to activate members of the matrix metalloproteinase and transforming growth factor-beta (TGF-beta) families, we sought to investigate the role of this gene family in murine implantation and embryogenesis. Using active site polymerase chain reaction (PCR) cloning, four members of the SPC family were identified at embryonic day 6.5: SPC1, SPC2, SPC3, and SPC6. In situ hybridization analysis of sectioned E6.5 embryos in utero demonstrated strong SPC6 expression in differentiated decidua, overlapping and extending beyond the region previously described for the metalloproteinase inhibitor TIMP-2. Lower levels of SPC6 expression were observed in trophoblasts and in the ectoplacental cone, suggesting multiple roles for this enzyme in implantation. Northern analysis showed that SPC6 mRNA in embryos is represented by two distinct sizes of message--the isoform SPC6-1 (3.0 kb) is most abundant at all stages, but significant levels of SPC6-b (6.0 kb) occur in E12.5 embryos. Whole mount in situ hybridization to E8.5 embryos demonstrated strong SPC6 expression in the most posterior somite. This somitic staining moved caudally with the developing embryo and by E10.5 became localized to the posterior of the tail, indicating that SPC6 is involved in somitogenesis. SPC6 was expressed at low levels throughout the embryo, except in the developing nervous system, and strong expression was observed in the first branchial arch and in skeletal regions of the developing vertebrae, limbs, and craniofacium, suggesting additional roles for SPC6 in skeletogenesis.

cDNA subtraction cloning reveals novel genes whose temporal and spatial expression indicates association with trophoblast invasion

Trophoblast invasion is a critical process in development of most mammals that shares similarities with the invasive behavior of tumor cells. In the present investigation, a cDNA subtraction library was constructed between invasive trophoblast at day 8 of murine development and mature noninvasive placenta at day 18 of gestation. One of the differentially expressed clones, Epcs26, was mapped to the X chromosome and revealed no homology to any known gene. It was predominantly expressed in parietal endoderm, undifferentiated cells of the ectoplacental cone, and a few trophoblast giant cells. Another gene, designated Epcs50, was mapped to chromosome 19. It exhibited homologies to the mouse Mps1 gene and, like Mps1, may have a distant relationship to the lytic protein perforin. High expression was detected in parietal endoderm cells and in a subset of secondary trophoblast giant cells. Two sequences, Epcs24 and Epcs68, exhibited an extensive open reading frame that shared the common features of the cysteine proteinase cathepsin L. Expression was confined to an undefined subpopulation of trophoblast giant cells. Both genes were mapped to chromosome 13 in close proximity to cathepsins L and J. The known functions of MPS1 and cathepsin L proteins indicate that the related proteins EPCS50, EPCS24, and EPCS68 participate in conferring invasive properties to the mouse trophoblast.

Impaired growth, delayed ossification, and reduced osteoclastic activity in the growth plate of calcium-supplemented rats with renal failure

Linear growth is reduced in prepubertal children with adynamic renal osteodystrophy, suggesting that the proliferation and/or differentiation of epiphyseal growth plate chondrocytes is abnormal in this disorder. To examine this issue, in situ hybridization and histochemistry were used to measure selected markers of endochondral bone formation and bone resorption in the proximal tibia of subtotally nephrectomized rats fed a high calcium diet to induce biochemical changes consistent with adynamic osteodystrophy. Blood ionized calcium concentrations were higher and serum PTH levels were lower in nephrectomized, calcium-supplemented rats than in either intact or nephrectomized control animals. Linear growth and tibial length were reduced, but messenger RNA levels for type II collagen, type X collagen, and the PTH/PTHrP receptor did not differ from control values in nephrectomized rats given supplemental calcium. In contrast, both the width of epiphyseal cartilage and the height of the zone of hypertrophic chondrocytes were greater in calcium-supplemented nephrectomized rats. These morphological changes were associated with decreases in histochemical staining for tartrate-resistant acid phosphatase and lower levels of messenger RNA expression for the matrix metalloproteinase MMP-9/gelatinase B immediately adjacent to the epiphyseal growth plate. Diminished chondroclastic/osteoclastic activity alters growth plate morphology and adversely affects linear bone growth in calcium-supplemented, nephrectomized rats.

Maternal influences on placental development

Epidemiological evidence suggests that size at birth may affect health in later life. The growth of the fetus may be adversely affected by a suboptimal maternal environment. Understanding placental development and function will help unravel the mechanisms controlling fetal growth. This article poses the problem: how does the maternal environment (uterine or systemic) influence placental development? Critical human placental functions include remodelling maternal uterine spiral arteries to increase the flow of blood to the maternofetal interface, and transferring oxygen and nutrients into the fetal vasculature, all processes involving trophoblast. Gene ablations that affect pregnancy outcome in mice lead to some interesting hypotheses.

Role of membrane-type matrix metalloproteinase 1 (MT-1-MMP), MMP-2, and its inhibitor in nephrogenesis

Extracellular matrix (ECM) proteins, their integrin receptors, and matrix metalloproteinases (MMPs), the ECM-degrading enzymes, are believed to be involved in various biological processes, including embryogenesis. In the present study, we investigated the role of membrane type MMP, MT-1-MMP, an activator pro-MMP-2, in metanephric development. Also, its relationship with MMP-2 and its inhibitor, TIMP-2, was studied. Since mRNAs of MT-1-MMP and MMP-2 are respectively expressed in the ureteric bud epithelia and mesenchyme, they are ideally suited for juxtacrine/paracrine interactions during renal development. Northern blot analyses revealed a single approximately 4.5-kb mRNA transcript of MT-1-MMP, and its expression was developmentally regulated. Inclusion of MT-1-MMP antisense oligodeoxynucleotide (ODN) in the culture media induced dysmorphogenetic changes in the embryonic metanephros. MMP-2 antisense ODN also induced similar changes, but they were relatively less; on the other hand TIMP-2 antisense ODN induced a mild increase in the size of explants. Concomitant exposure of MT-1-MMP and MMP-2 antisense ODNs induced profound alterations in the metanephroi. Treatment of TIMP-2 antisense ODN to metanephroi exposed to MT-1-MMP/MMP-2 antisense notably restored the morphology of the explants. Specificity of the MT-1-MMP antisense ODN was reflected in the selective decrease in its mRNA and protein expression. The MT-1-MMP antisense ODN also resulted in a failure in the activation of pro-MMP-2 to MMP-2. These findings suggest that the trimacromolecular complex of MT-1-MMP:MMP-2:TIMP-2 modulates the organogenesis of the metanephros, conceivably by mediating paracrine/juxtacrine epithelial:mesenchymal interactions.

Prolactin (PRL)-like protein J, a novel member of the PRL/growth hormone family, is exclusively expressed in maternal decidua

A search of a nonmouse, nonhuman, expressed sequence tag database for messenger RNAs in the PRL/GH family has identified a novel rat complementary DNA clone. The encoded protein, designated PRL-like protein J (PLP-J), is predicted to be synthesized as a precursor of 211 amino acids, modified by N-linked glycosylation, and secreted as a mature glycoprotein of 182 residues. PLP-J messenger RNA synthesis is limited to early pregnancy with abundant expression on day 7, slightly declining expression on day 9, and no detectable expression by day 11. Unlike most other PRL family members, PLP-J does not appear to be synthesized by placental trophoblasts but, rather, by decidual cells surrounding the implantation site. By sequence similarity to rat PLP-J, a murine clone was identified in a mouse expressed sequence tag database. Mouse PLP-J was used to map the gene to a 700-kb region of mouse chromosome 13 that includes other members of the PRL/GH family.

Timp-1 is important for epithelial proliferation and branching morphogenesis during mouse mammary development

The dynamic process of mammary ductal morphogenesis depends on regulated epithelial proliferation and extracellular matrix (ECM) turnover. Epithelial cell-matrix contact closely dictates epithelial proliferation, differentiation, and survival. Despite the fact that tissue inhibitors of metalloproteinases (Timps) regulate ECM turnover, their function in mammary morphogenesis is unknown. We have delineated the spatiotemporal expression of all Timps (Timp-1 to Timp-4) during discrete phases of murine mammary development. Timp mRNAs were abundant in mammary tissue, each displaying differential expression patterns with predominant localization in luminal epithelial cells. Timp-1 mRNA was unique in that its expression was limited to the stage at which epithelial proliferation was high. To assess whether Timp-1 promotes or inhibits epithelial cell proliferation we manipulated mammary Timp-1 levels, genetically and biochemically. Down-regulation of epithelial-derived Timp-1 in transgenic mice, by mouse mammary tumor virus promoter-directed Timp-1 antisense RNA expression, led to augmented ductal expansion and increased number of ducts (P < 0.004). In these transgenics the integrity of basement membrane surrounding epithelial ducts, as visualized by laminin-specific immunostaining, was breached. In contrast to these mice, ductal expansion was markedly attenuated in the proximity of implanted recombinant Timp-1-releasing pellets (rTIMP-1), without an increase in basement membrane deposition around migrating terminal end buds. Epithelial proliferation and apoptosis were measured to determine the basis of altered ductal expansion. Luminal epithelial proliferation was increased by 55% (P < 0.02) in Timp-1-reduced transgenic mammary tissue and, conversely, decreased by 38% (P < 0.02) in terminal end buds by implanted rTIMP-1. Epithelial apoptosis was minimal and remained unaffected by Timp-1 manipulations. We conclude that Timps have an integral function in mammary morphogenesis and that Timp-1 regulates mammary epithelial proliferation in vivo, at least in part by maintaining basement membrane integrity.

Examining the relationship between the gelatinolytic balance and the invasive capacity of endothelial cells

Angiogenesis and the formation of new blood vessels requires coordinated regulation of matrix proteolysis and endothelial cell migration. Cellular proteolytic capacity is the balance between secreted matrix metalloproteinases (MMP) and their inhibitors (TIMPs). We have examined the regulation of the gelatinase/TIMP balance by transforming growth factor-beta1 (TGF-beta1) and phorbol myristate acetate (PMA) in bovine endothelial cells. The low constitutive expression of gelatinase A/MMP-2 was upregulated by TGF-beta1 in a dose-dependent manner. Gelatinase B/MMP-9 was only detected upon treatment with either PMA or TGF-beta1. However, addition of both factors together revealed a striking synergistic effect causing upregulation of MMP-9 and downregulation of TIMPs, thereby increasing the net MMP-9/TIMP balance and the gelatinolytic capacity. These effects were observed at both the protein and mRNA levels. We demonstrate that changes in different members of the Jun oncogene family with distinct transactivation properties may account for this synergistic effect. We investigated the contribution of these changes in gelatinolytic balance to endothelial cell migration and invasion. The endothelial cells showed increased cell motility in response to PMA, but the addition of TGF-beta1 had an inhibitory effect. Hence, regulation of the MMP-9/TIMP balance failed to correlate with the migratory or invasive capacity. These results question a direct role for MMP-9 in endothelial cell motility and suggest that gelatinases may contribute in alternative ways to the angiogenic process.

Gelatinases A and B and tissue inhibitors of metalloproteinases 1, 2, and 3 during in vivo and in vitro decidualization of rat endometrial stromal cells

An important event during decidualization is the remodeling of the extracellular matrix, an event controlled by the balance of matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). A putative regulator of decidualization is prostaglandin E2 (PGE2). The present study shows that endometrial mRNA levels for TIMPs 1, 2, and 3 were increased while gelatinase A levels remained unchanged and gelatinase B levels decreased during oil-induced decidualization. The production of TIMPs 1, 2, and 3 and gelatinases A and B during in vitro decidualization was examined, as was the role of PGE2 as a regulator. Ovariectomized rats were given a regimen of estrogen and progesterone, which sensitized their uteri for decidualization, at which time endometrial stromal cells were isolated and cultured in serum-free conditions for 72 h. Northern blot analyses indicated the presence of the mRNAs for TIMPs and gelatinases, while reverse zymography and zymography showed the presence of their proteins. PGE2 decreased mRNA levels for TIMP-1 and gelatinase A but had no effect on gelatinase B or TIMPs 2 and 3. Indomethacin had no effect on any of the transcripts. These data indicate that rat endometrial stromal cells undergoing decidualization in vitro secrete gelatinases and TIMPs, and suggest that PGE2 may play a role in regulating tissue remodeling during decidualization.

Synergistic role of nitric oxide and progesterone during the establishment of pregnancy in the rat

Successful pregnancy is strictly dependent on the trophoblast-decidual interaction and on an adequate blood supply to the implantation sites. Nitric oxide (NO) has been shown to play an important role during advanced gestation, although its role during early pregnancy is unclear. The aim of the present study in rats was to evaluate whether NO plays a role during the preimplantation [days 1-4 post coitum (p.c.)] and peri-implantation (days 6-8 p.c.) phases of pregnancy. The rats were treated with the non-specific nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME), and the iNOS inhibitor aminoguanidine in the presence and absence of low-dose antiprogestin, onapristone, and evaluated on days 9 p.c. and 19 p.c., respectively. Before implantation, the treatments alone (L-NAME, aminoguanidine, onapristone) had little effect on pregnancy outcome. Conversely, aminoguanidine plus onapristone treatment completely prevented pregnancy, whereas L-NAME plus onapristone reduced the pregnancy rate to approximately 50%. In addition, both treatments drastically reduced decidualization. Oviductal flushing experiments revealed arrest of embryo development at around the 8-cell stage after aminoguanidine plus onapristone treatment on days 1-4 p.c. Similarly, treatment during the peri-implantation period with L-NAME, aminoguanidine, and onapristone each had only marginal effects on pregnancy. However, a combination of L-NAME and onapristone, and aminoguanidine plus onapristone prevented pregnancy in 71% and 42% of dams, respectively, as determined on day 19 p.c. These treatments also markedly inhibited the decidualization process. This study demonstrates synergistic effects of NOS inhibitors and an antiprogestin in preventing pregnancy. NOS, particularly the cytokine- and progesterone-inducible iNOS, may represent a new target for novel therapeutic agents capable of promoting or inhibiting pregnancy.

Tissue inhibitors of metalloproteinases (TIMP) in invasion and proliferation

Tissue inhibitors of matrix metalloproteinases (TIMPs) are a family of natural inhibitors that control the activity of matrix metalloproteinases (MMPs) in the extracellular matrix (ECM). Four members of this family have been so far characterized in a variety of species. These inhibitors share a similar structural feature characterized by the presence of 12 cysteine residues involved in disulfide bonds and a similar function by their ability to form inhibitory complexes with MMPs. The role of TIMPs in cancer has been the subject of conflicting reports with an antitumor activity reported by some investigators and a growth stimulation activity reported by others. Here we will discuss a series of data obtained in our laboratory supporting a role of TIMPs not only as inhibitors of invasion but also as regulators of cell growth. Using placental development as an example of a regulated invasive process, we have observed that the levels of TIMP-2 and TIMP-3 steadily increase between day 14.5 and 17.5 post-coitus. TIMPs are selectively expressed by spongiotrophoblastic cells that separate the labyrinthine zone, rich in fetal blood vessels and maternal blood sinuses, from the zone of giant cells forming the border between fetal and maternal tissues. TIMPs are also potent inhibitors of tumor growth in vivo. In melanoma cells, we have previously reported that over-expression of TIMP-2 inhibits the growth of tumors implanted in the skin of scid mice. This growth inhibition seems independent of angiogenesis but dependent on the collagen matrix. We observed that in the presence of fibrillar type I collagen, melanoma cells undergo a growth arrest at the G1 to S interphase transition of the cell cycle. This arrest is specific to the fibrillar structure of collagen because it is not observed in the presence of non-fibrillar collagen or other ECM components. It is associated with a specific upregulation of the cyclin inhibitor p27KIP1. The data therefore indicate that anchorage independent cells remain sensitive to growth regulatory signals that originate from the ECM and that these signals can specifically block tumor cell cycle. Thus our concept of the role of protease inhibitors such as TIMPs in cancer has substantially changed from an initial focus on inhibition of tumor invasion and metastasis to a broader focus on being molecules that--via their function as regulators of the ECM homeostasis--can control tumor cell growth.

Matrix-degrading proteases and angiogenesis during development and tumor formation

Embryonic development and tumor progression both require the exquisite coordination of programs for extracellular matrix (ECM) formation and remodeling, and those for angiogenesis and vascular development. Without a vascular supply the normal tissue or tumor is limited in size and organization. Without ECM remodeling the alteration of tissue and tumor boundaries and cellular migrations are limited. Recent insights into the molecular mechanisms regulating the extracellular environment of the growing embryonic tissue or tumors have implicated proteases, the matrix metalloproteinases (MMPs) in particular, in both the process of ECM remodeling and angiogenesis, and in a potential causal relationship between these processes. This review focuses on the roles that MMPs play in regulating three processes in which both proteolysis and vascular development are tightly coordinated: embryo implantation, bone development and tumor progression.

Localization of matrix metalloproteinase 9 to the cell surface provides a mechanism for CD44-mediated tumor invasion

The cell surface hyaluronan receptor CD44 promotes tumor growth and metastasis by mechanisms that remain poorly understood. We show here that CD44 associates with a proteolytic form of the matrix metalloproteinase-9 (MMP-9) on the surface of mouse mammary carcinoma and human melanoma cells. CD44-associated cell surface MMP-9 promotes cell-mediated collagen IV degradation in vitro and mediates tumor cell invasion of G8 myoblast monolayers. Several distinct CD44 isoforms coprecipitate with MMP-9 and CD44/MMP-9 coclustering is observed to be dependent on the ability of CD44 to form hyaluronan-induced aggregates. Disruption of CD44/MMP-9 cluster formation, by overexpression of soluble or truncated cell surface CD44, is shown to inhibit tumor invasiveness in vivo. Our observations indicate that CD44 serves to anchor MMP-9 on the cell surface and define a mechanism for CD44-mediated tumor invasion.

Expression of adrenomedullin, a hypotensive peptide, in the trophoblast giant cells at the embryo implantation site in mouse

Adrenomedullin (AM) is a newly discovered hypotensive peptide which is believed to play an important role for blood pressure control in the adult. Although it has been well established that a major production site of AM is vascular endothelial cells, we now show that AM is most highly expressed in trophoblast giant cells, which are derived from the conceptus and are directly in contact with maternal tissues at the implantation site. Northern blot and in situ hybridization analyses show that the AM mRNA begins to be detected just after implantation and its level peaks at 9.5 days postconception (d.p.c.) in those cells. Expression then falls dramatically after 10.5 d.p.c., coincident with the completion of the mature chorioallantoic placenta. Immunohistochemical analyses show that the AM peptide is secreted from the trophoblast giant cells into the surrounding tissues, i.e., embryo, decidua, and maternal circulation. In contrast, the expression of an AM receptor was not detected by Northern blot analyses in either embryo or trophoblast giant cells at 7 d.p.c., when the AM gene is most highly expressed in the trophoblast giant cells. This suggests that the AM produced and secreted from the embryo's trophoblast giant cells acts on the maternal tissues rather than on the embryonic tissues. Based on these results, we propose that the high production of AM may be the mechanism by which the embryos survive at the early postimplantation period by pooling maternal blood in the implantation site in order to secure nutrition and oxygen before the establishment of efficient embryo-maternal circulation through the mature placenta.

Extracellular matrix remodeling during morphogenesis

The role of proteinases in extracellular matrix remodeling during the developmental program of bone, cartilage, muscle, and epithelial differentiation in the mandibular arch during embryogenesis was investigated. ECM changes accompany morphogenesis during development. The most dramatic changes occur during development of bone and cartilage. The expression of matrix metalloproteinases (MMPs) was altered by regulating expression of MMPs by growth factors, by inhibiting MMP activity, and by genetic ablation of MMPs. The data point to critical roles for MMPs in cartilage development and endochondral bone formation. MMPs appear to regulate not only ECM degradation but also programmed cell death, cell migration, and invasion during these morphogenic processes. The data suggest that matrix metalloproteinases play a pivotal role in the morphogenesis of structures derived from epithelium (oral sulcus), somitic mesoderm (tongue), and cranial neural crest (Meckel's cartilage).

Formation of the placenta and extraembryonic membranes

In eutherian mammals, the first cell types that are specified during embryogenesis are committed to form extraembryonic (placenta and fetal membranes) rather than embryonic structures. The trophoblast cell lineage, for example, forms at the morula-to-blastocyst transition: cells at the periphery of the morula become trophoblast, whereas cells on the inside remain undifferentiated embryonic ectoderm, which later gives rise to the fetus as well as the endodermal and mesodermal components of the placenta and extraembryonic membranes. Genetic studies in mice are beginning to identify growth factors and cell adhesion molecules that mediate interactions between cell types that are essential for morphogenesis of the placenta and fetal membranes, as well as transcription factors that control the differentiation of extraembryonic cell types.

Characterization of the gene for human EMMPRIN, a tumor cell surface inducer of matrix metalloproteinases

EMMPRIN (extracellular matrix metalloproteinase inducer) also known as CD147 and basigin, is a member of the immunoglobulin family that is present on the surface of tumor cells and stimulates nearby fibroblasts to synthesize matrix metalloproteinases. Using our EMMPRIN cDNA, we have isolated a cosmid clone that contains the human EMMPRIN gene. S1 analysis with a fragment of the gene clone and primer extension of the mRNA was performed to determine the transcription start site. PCR and sequence analysis have defined the exon/intron organization of the gene and show that it is highly conserved with the mouse EMMPRIN/basigin gene. About 950 bases of the 5'-flanking region were examined for transcription factor consensus binding sites, locating three SP1 sites and two AP2 sites. The transcription start site was found to be located in a CpG island. Elements in the proximal promoter region were conserved in the human and mouse genes.

Trophoblast pseudo-vasculogenesis: faking it with endothelial adhesion receptors

During early development, a subset of fetal (placental) cytotrophoblasts exhibits tumor-like behavior and invades the uterus. To access a supply of maternal blood, they invade arterioles and form heterotypic interactions with, and replace, resident maternal endothelium, creating a hybrid uterine vasculature. Recently, it has become clear that invading cytotrophoblasts transform their adhesion receptor phenotype to resemble the endothelial cells they replace. Furthermore, they express vasculogenic factors and receptors. Is this a form of vasculogenesis?

Expression and function of the urokinase type plasminogen activator during mouse hemochorial placental development

Mouse midlate placental development involves extensive tissue remodeling and cell invasion, processes which could be mediated by extracellular proteolytic enzymes. We have performed in situ expression analysis of urokinase type plasminogen activator (uPA), as well as functionally related molecules (uPA receptor, low density lipoprotein receptor-related protein, plasminogen activator inhibitor type-1) in day 10.5 to 18.5 post coitum (p.c.) murine placentas. In situ hybridization demonstrated the presence of uPA transcripts in the invasive trophoblast cells, in particular in glycogen-rich trophoblasts, a cell population that between embryonic days 12.5 and 15.5 infiltrates the maternal decidual tissue. In addition, we observed high uPA expression in the cells of uterine epithelium. Enzymatically active uPA was detected in both sites of uPA mRNA expression by in situ zymography. Expression and activity data suggest a role for this protease in the processes of cell invasion and uterine epithelial remodeling. Only low levels of uPA receptor (uPAR) transcripts were found in trophoblasts and decidual tissue at days 10.5 and 11.5 p.c. At the same stages, a prominent expression of plasminogen activator inhibitor type-1 (PAI-1) by spongiotrophoblasts and giant trophoblasts, as well as of LDL receptor-related protein (LRP) by spongiotrophoblasts and decidual cells could be detected, suggesting a role in regulating extracellular proteolysis in the area of fetomaternal interface. Analysis of uPA null placentas showed the presence of decidual extravascular fibrin deposits, which were not detected in wild type placentas. At the same time, the extent of infiltration of trophoblast cells in maternal decidual tissue, evaluated by anti-cytokeratin immunostaining, was similar in wild type and uPA null placentas. Our studies show that in murine hemochorial placentation, uPA has an essential role in the maintenance of the fibrinogenic/fibrinolytic balance in the decidua. The function of uPA in trophoblast invasion appears not to be indispensable, and its absence can be overcome by redundant or compensatory mechanisms.

Demonstration of extracellular acid phosphatase activity in the involuting, antimesometrial decidua in fed and acutely fasted mice by combined cytochemistry and electron microscopy

An ultrastructural cytochemical study of acid phosphatase activity in the antimesometrial decidua on days 9-11 of pregnancy was performed in fed and acutely fasted mice. Specimens were fixed in a buffered mixture of paraformaldehyde and glutaraldehyde and were incubated in a buffered medium containing sodium beta-glycerophosphate and cerium chloride for ultrastructural localization of acid phosphatase activity. Fed and fasted animals showed extracellular acid phosphatase reaction product in the decidual-trophoblast interface, in the region of loosely and tightly packed, mature decidual cells, and in the region of predecidual cells. Reaction product was absent in the region of nondecidualized stromal cells. Extracellular acid phosphatase activity was more conspicuous in the region of mature decidual cells in fasted mice than in fed mice, and it was apparently similar in the region of predecidual cells in both fed and fasted mice. Acid phosphatase reaction product was also observed in lysosomes in all cells studied. Because acid phosphatase activity reflects the presence of lysosomal hydrolases in general, our results suggest that there is matrix degradation by lysosomal enzymes in both fed and fasted mice. These events may be part of the process of tissue remodeling in regions of predecidual cells and mature decidual cells. However, it is also possible that, in the region of mature decidual cells, breakdown of matrix constituents is a mechanism to provide nutrients for the growing fetus. This mechanism is probably enhanced in fasted mice.

The asymmetric synthesis and in vitro characterization of succinyl mercaptoalcohol and mercaptoketone inhibitors of matrix metalloproteinases

A series of succinyl based mercaptoketones and diastereomeric mercaptoalcohols were prepared and evaluated in vitro as inhibitors of the matrix metalloproteinases collagenase-1 (MMP-1), stromelysin (MMP-3), and gelatinase-B (MMP-9).

MMP-9/gelatinase B is a key regulator of growth plate angiogenesis and apoptosis of hypertrophic chondrocytes

Homozygous mice with a null mutation in the MMP-9/gelatinase B gene exhibit an abnormal pattern of skeletal growth plate vascularization and ossification. Although hypertrophic chondrocytes develop normally, apoptosis, vascularization, and ossification are delayed, resulting in progressive lengthening of the growth plate to about eight times normal. After 3 weeks postnatal, aberrant apoptosis, vascularization, and ossification compensate to remodel the enlarged growth plate and ultimately produce an axial skeleton of normal appearance. Transplantation of wild-type bone marrow cells rescues vascularization and ossification in gelatinase B-null growth plates, indicating that these processes are mediated by gelatinase B-expressing cells of bone marrow origin, designated chondroclasts. Growth plates from gelatinase B-null mice in culture show a delayed release of an angiogenic activator, establishing a role for this proteinase in controlling angiogenesis.

Reprogramming the cell cycle for endoreduplication in rodent trophoblast cells

Differentiation of trophoblast giant cells in the rodent placenta is accompanied by exit from the mitotic cell cycle and onset of endoreduplication. Commitment to giant cell differentiation is under developmental control, involving down-regulation of Id1 and Id2, concomitant with up-regulation of the basic helix-loop-helix factor Hxt and acquisition of increased adhesiveness. Endoreduplication disrupts the alternation of DNA synthesis and mitosis that maintains euploid DNA content during proliferation. To determine how the mammalian endocycle is regulated, we examined the expression of the cyclins and cyclin-dependent kinases during the transition from replication to endoreduplication in the Rcho-1 rat choriocarcinoma cell line. We cultured these cells under conditions that gave relatively synchronous endoreduplication. This allowed us to study the events that occur during the transition from the mitotic cycle to the first endocycle. With giant cell differentiation, the cells switched cyclin D isoform expression from D3 to D1 and altered several checkpoint functions, acquiring a relative insensitivity to DNA-damaging agents and a coincident serum independence. The initiation of S phase during endocycles appeared to involve cycles of synthesis of cyclins E and A, and termination of S was associated with abrupt loss of cyclin A and E. Both cyclins were absent from gap phase cells, suggesting that their degradation may be necessary to allow reinitiation of the endocycle. The arrest of the mitotic cycle at the onset of endoreduplication was associated with a failure to assemble cyclin B/p34(cdk1) complexes during the first endocycle. In subsequent endocycles, cyclin B expression was suppressed. Together these data suggest several points at which cell cycle regulation could be targeted to shift cells from a mitotic to an endoreduplicative cycle.

Human TIMP-3 is expressed during fetal development, hair growth cycle, and cancer progression

We studied the expression and regulation of TIMP-3, a recently cloned member of the tissue inhibitor of the metalloproteinase family, during human fetal development and in various human tissues, with emphasis on epithelial structures. Expression of TIMP-3 mRNA was detected by in situ hybridization in developing bone, kidney, and various mesenchymal structures. At 16 weeks of gestation, ectoderm-derived cells of hair germs expressed TIMP-3 mRNA, and beginning from the twentieth week consistent expression was detected in epithelial outer root sheath cells of growing hair follicles. In normal adult human skin, expression of TIMP-3 mRNA was limited to hair follicles, starting at the early anagen (growing) phase and vanishing at the catagen (regressing) phase. TIMP-3 mRNA was not detected in benign hair follicle-derived tumors but was present in tumor cells of infiltrative basal cell carcinomas and in surrounding stromal cells in squamous cell carcinomas. Human primary keratinocytes in culture expressed TIMP-3 mRNAs, the levels of which were upregulated by transforming growth factor-beta (TGF-beta), whereas interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) had no effect. Our results suggest a role for TIMP-3 in connective tissue remodeling during fetal development, hair growth cycle, and cancer progression.

Infertility in female mice lacking the receptor for interleukin 11 is due to a defective uterine response to implantation

During early pregnancy, in response to the implanting embryo, the surrounding uterine stroma undergoes a dramatic transformation into a specialized tissue known as the decidua. The decidua encapsulates the developing embryo, facilitating nutrient transfer and limiting trophoblast invasion. Here we show that female mice with a null mutation of the interleukin-11 receptor alpha chain are infertile because of defective decidualization. A temporal analysis revealed IL-11 expression is maximal in the normal pregnant uterus at the time of decidualization, and in situ hybridization studies showed expression of the IL-11 and the IL-11 receptor alpha chain in the developing decidual cells. These observations reveal a previously unrecognized critical role for IL-11 signaling in female reproduction.

Expression of neuropsin mRNA in the mouse embryo and the pregnant uterus

Neuropsin is a novel serine protease whose mRNA is expressed in the mouse central nervous system. We examined the expression of neuropsin mRNA during embryonic development using Northern and in situ hybridization in non-neural tissues. The pregnant uterus showed strong expression of neuropsin mRNA, whereas the nonpregnant uterus did not express this mRNA. Expression was first detected in the primary decidual zone at 5.5 days post coitum and was maximized at 10 days post coitum, decreasing remarkably thereafter. During mouse organogenesis, neuropsin expression was observed in the developing heart, lung, thymus, pituitary, choroid plexus, and epithelial linings of the skin, oral cavity, tongue, esophagus, and forestomach. In adult mouse organs, neuropsin mRNA was expressed in epithelial tissues covered by keratinocytes with moderate density, whereas low expression was observed in lung, thymus, and spleen. Neuropsin mRNA expression in developing organs and adult keratinocytes suggests that neuropsin is associated with extracellular matrix modifications and cell migrations.