Temporal and spatial expression of integrins and their extracellular matrix ligands at the maternal-fetal interface in the rhesus monkey during pregnancy

Sexual dimorphism in placental development and function: Comparative physiology with an emphasis on the pig

Across mammalian species, it has been demonstrated that sex influences birth weight, with males being heavier than females; a characteristic that can be observed from early gestation. Male piglets are more likely to be stillborn and have greater preweaning mortality than their female littermates, despite the additional maternal investment into male fetal growth. Given the conserved nature of the genome between the sexes, it is hypothesized that these developmental differences between males and females are most likely orchestrated by differential placental adaptation. This review summarizes the current understanding of fetal sex-specific differences in placental and endometrial structure and function, with an emphasis on pathways found to be differentially regulated in the pig including angiogenesis, apoptosis, and proliferation. Given the importance of piglet sex in agricultural enterprises, and the potential for skewed litter sex ratios, it is imperative to improve understanding of the relationship between fetal sex and molecular signaling in both the placenta and endometria across gestation.

Evolutionary divergence of embryo implantation in primates

Implantation of the conceptus into the uterus is absolutely essential for successful embryo development. In humans, our understanding of this process has remained rudimentary owing to the inaccessibility of early implantation stages. Non-human primates recapitulate many aspects of human embryo development and provide crucial insights into trophoblast development, uterine receptivity and embryo invasion. Moreover, primate species exhibit a variety of implantation strategies and differ in embryo invasion depths. This review examines conservation and divergence of the key processes required for embryo implantation in different primates and in comparison with the canonical rodent model. We discuss trophectoderm compartmentalization, endometrial remodelling and embryo adhesion and invasion. Finally, we propose that studying the mechanism controlling invasion depth between different primate species may provide new insights and treatment strategies for placentation disorders in humans. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.

Association of foetal size and sex with porcine foeto-maternal interface integrin expression

Integrins regulate adhesion at the foeto-maternal interface by interacting with secreted phosphoprotein 1 (SPP1) and fibronectin (FN). It is hypothesised that impaired foetal growth of ‘runt’ piglets is linked to altered integrin signalling at the foeto-maternal interface. Placental and endometrial samples associated with the lightest and closest to mean litter weight (CTMLW) (gestational day (GD18, 30, 45, 60 and 90), of both sex (GD30, 45, 60 and 90) (n = 5–8 litters/GD), Large White × Landrace conceptuses or foetuses were obtained. The mRNA expression of the integrin subunits (ITG) ITGA2, ITGAV, ITGB1, ITGB3, ITGB5, ITGB6, ITGB8, SPP1 and FN was quantified by qPCR. Temporal changes in mRNA expression were observed, with different profiles in the two tissues. Endometrial ITGB1 (P ≤ 0.05, GD45) and SPP1 (P ≤ 0.05, all GD combined and GD60) expression was decreased in samples supplying the lightest compared to the CTMLW foetuses. Placentas supplying female foetuses had decreased expression of ITGB6 (GD45, P ≤ 0.05) and FN (GD90, P ≤ 0.05) compared to those supplying male foetuses. Endometrial samples supplying females had increased ITGB3 (P ≤ 0.05, GD60) and FN (P ≤ 0.05, GD30) expression and decreased SPP1 (P ≤ 0.05, GD60) expression compared to male foetuses. Correlations between mean within-gilt mRNA expression and percentage prenatal survival, number of live foetuses or conceptuses and percentage male foetuses were observed. This study has highlighted novel and dynamic associations between foetal size, sex and integrin subunit mRNA expression at the porcine foeto-maternal interface. Further studies should be performed to improve the understanding of the mechanisms behind these novel findings.

Endometrial vascular development in heavy menstrual bleeding: altered spatio-temporal expression of endothelial cell markers and extracellular matrix components

STUDY QUESTION

Are there any phenotypic and structural/architectural changes in the vessels of endometrium and superficial myometrium during the normal menstrual cycle in healthy women and those with heavy menstrual bleeding (HMB)?

SUMMARY ANSWER

Spatial and temporal differences in protein levels of endothelial cell (EC) markers and components of the extracellular matrix (ECM) were detected across the menstrual cycle in healthy women and these are altered in HMB.

WHAT IS KNOWN ALREADY

HMB affects 30% of women of reproductive age with ~50% of cases being idiopathic. We have previously shown that the differentiation status of endometrial vascular smooth muscle cells (VSMCs) is altered in women with HMB, suggesting altered vessel maturation compared to controls. Endometrial arteriogenesis requires the co-ordinated maturation not only of the VSMCs but also the underlying ECs and surrounding ECM. We hypothesized that there are spatial and temporal patterns of protein expression of EC markers and vascular ECM components in the endometrium across the menstrual cycle, which are altered in women with HMB.

STUDY DESIGN, SIZE, DURATION

Biopsies containing endometrium and superficial myometrium were taken from hysterectomy specimens from both healthy control women without endometrial pathology and women with subjective HMB in the proliferative (PP), early secretory (ESP), mid secretory (MSP) and late secretory (LSP) phases (N = 5 for each cycle phase and subject group). Samples were fixed in formalin and embedded in paraffin wax.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Serial sections (3μm thick) were immunostained for EC markers (factor VIII related antigen (F8RA), CD34, CD31 and ulex europaeus-agglutinin I (UEA-1) lectin), structural ECM markers (osteopontin, laminin, fibronectin and collagen IV) and for Ki67 to assess proliferation. Immunoreactivity of vessels in superficial myometrium, endometrial stratum basalis, stratum functionalis and luminal region was scored using either a modified Quickscore or by counting the number of positive vessels.

MAIN RESULTS AND THE ROLE OF CHANCE

In control samples, all four EC markers showed a dynamic expression pattern according to the menstrual cycle phase, in both endometrial and myometrial vessels. EC protein marker expression was altered in women with HMB compared with controls, especially in the secretory phase in the endometrial luminal region and stratum functionalis. For example, in the LSP expression of UEA-1 and CD31 in the luminal region decreased in HMB (mean quickscore: 1 and 5, respectively) compared with controls (3.2 and 7.4, respectively) (both P = 0.008), while expression of F8RA and CD34 increased in HMB (1.4 and 8, respectively) compared with controls (0 and 5.8, respectively) (both P = 0.008). There was also a distinct pattern of expression of the vascular structural ECM protein components osteopontin, laminin, fibronectin and collagen IV in the superficial myometrium, stratum functionalis and stratum basalis during the menstrual cycle, which was altered in HMB. In particular, compared with controls, osteopontin expression in HMB was higher in stratum functionalis in the LSP (7.2 and 11.2, respectively P = 0.008), while collagen IV expression was reduced in stratum basalis in the MSP (4.6 and 2.8, respectively P = 0.002) and in stratum functionalis in the ESP (7 and 3.2, respectively P = 0.008).

LIMITATIONS, REASONS FOR CAUTION

The protein expression of vascular EC markers and ECM components was assessed using a semi-quantitative approach in both straight and spiral arterioles. In our hospital, HMB is determined by subjective criteria and levels of blood loss were not assessed.

WIDER IMPLICATIONS OF THE FINDINGS

Variation in the protein expression pattern between the four EC markers highlights the importance of choice of EC marker for investigation of endometrial vessels. Differences in expression of the different EC markers may reflect developmental stage dependent expression of EC markers in endometrial vessels, and their altered expression in HMB may reflect dysregulated vascular development. This hypothesis is supported by altered expression of ECM proteins within endometrial vessel walls, as well as our previous data showing a dysregulation in VSMC contractile protein expression in the endometrium of women with HMB. Taken together, these data support the suggestion that HMB symptoms are associated with weaker vascular structures, particularly in the LSP of the menstrual cycle, which may lead to increased and extended blood flow during menstruation.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Wellbeing of Women (RG1342) and Newcastle University. There are no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Placenta Accreta Spectrum: A Review of Pathology, Molecular Biology, and Biomarkers

Background. Placenta accreta spectrum (PAS) is a condition of abnormal placental invasion encompassing placenta accreta, increta, and percreta and is a major cause of severe maternal morbidity and mortality. The diagnosis of a PAS is made on the basis of histopathologic examination and characterised by an absence of decidua and chorionic villi are seen to directly adjacent to myometrial fibres. The underlying molecular biology of PAS is a complex process that requires further research; for ease, we have divided these processes into angiogenesis, proliferation, and inflammation/invasion. A number of diagnostic serum biomarkers have been investigated in PAS, including human chorionic gonadotropin (HCG), pregnancy-associated plasma protein-A (PAPP-A), and alpha-fetoprotein (AFP). They have shown variable reliability and variability of measurement depending on gestational age at sampling. At present, a sensitive serum biomarker for invasive placentation remains elusive. In summary, there are a limited number of studies that have contributed to our understanding of the molecular biology of PAS, and additional biomarkers are needed to aid diagnosis and disease stratification.

Altered β1,6-GlcNAc and bisecting GlcNAc-branched N-glycan on integrin β1 are associated with early spontaneous miscarriage in humans

STUDY QUESTION

Do N-acetylglucosaminyltransferase (GnT-V) and N-acetylglucosaminyltransferase III (GnT-III) play an important role in early spontaneous miscarriage (ESM) in humans.

SUMMARY ANSWER

The dynamic balance between GnT-V and GnT-III expression in chorionic villi differed between early normal pregnancy and ESM and was associated with altered β1,6-N-acetylglucosamine (β1,6-GlcNAc) and bisecting N-acetylglucosamine (bis-GlcNAc) branched N-glycans on integrin β1.

WHAT IS KNOWN ALREADY

GnT-V contributes to metastasis, while GnT-III is recognized as a metastasis suppressor. It has been reported that GnT-V contributes to placentation in the early phase of pregnancy, possibly regulating trophoblast invasion. However, the expressions of GnT-V and GnT-III in ESM have not been reported.

STUDY DESIGN, SIZE, DURATION

Villous samples from 6 to 9 weeks of gestation were collected in the First Affiliated Hospital of Chongqing Medical University from May 2013 to September 2014 from 60 normal pregnant women undergoing elective termination of pregnancy and from 40 patients with a clinical diagnosis of ESM.

PARTICIPANTS, MATERIALS, SETTING, METHODS

Quantitative PCR and western blots were used to examine the GnT-V and GnT-III mRNA (Mgat5 and Mgat3) and protein expression, respectively, of chorionic villi in both the ESM group and the normal group from week 6 to week 9. We used immunofluorescence and immunohistochemistry to detect the location of GnT-V and GnT-III. Lectin fluorescence and histochemistry were used to test the location of β1,6-GlcNAc and bis-GlcNAc branching in the normal and ESM groups. To assess the functional capacity of GnT-V and GnT-III in the chorionic villi between the two groups, we used an enzyme-linked immunosorbent assay kit to measure the activity of these enzymes. Using co-precipitated integrin α5β1 followed by phytohaemagglutinin (PHA)-L and PHA-E blotting, we investigated whether GnT-V and GnT-III could modify the N-glycosylation profile in terms of the β1,6-GlcNAc and bis-GlcNAc structures in integrin α5β1 during the first trimester in both groups.

MAIN RESULTS AND THE ROLE OF CHANCE

In the normal group expression and activity of GnT-V and the concentration of its product, β1,6-GlcNAc were higher at week 9 than at weeks 6, 7 and 8 (P < 0.05). In contrast, the expression and activity of GnT-III and the concentration of its product, bis-GlcNAc were higher at week 6 than at weeks 7, 8 and 9 (P < 0.05). Compared with the normal group, the ESM group exhibited a lower expression of GnT-V and β1,6-GlcNAc (P < 0.05) and a higher expression of GnT-III and bis-GlcNAc (P < 0.05) with consistent changes in enzymatic activity. Immunofluorescence showed that GnT-V was located mainly in the cytoplasm of syncytiotrophoblasts (STBs) and chorionic villous cytotrophoblasts (CTBs), in both the ESM group and the normal group. β1,6-GlcNAc N-glycan was mainly located outside of the STB and CTB layer in normal villi and was expressed only rarely in the ESM villi. GnT-III was expressed primarily in the cytoplasm of STBs and expressed only very weakly in the CTBs of normal villi, whereas it was highly expressed in both the STBs and CTBs in the ESM group. bis-GlcNAc was primarily located outside of the STBs in the normal villi, whereas it was expressed much more abundantly outside of both the STBs and CTBs in the ESM group at each week of gestation. Moreover, decreased β1,6-GlcNAc-branched N-glycans and increased bis-GlcNAc-branched N-glycans on integrin β1 (P < 0.05) were observed in the ESM group.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide a new insight for studying the mechanism of clinical ESM in humans and it might be valuable for the clinical diagnosis and treatment of ESM.

LIMITATIONS, REASONS FOR CAUTION

The study lacks experiments in vitro to disclose the precise mechanism by which GnT-V and GnT-III regulate ESM. In some cases, degradation of the tissues after the miscarriage event cannot be ruled out.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by grants from the National Natural Science Foundation of China (31271546). The authors have no competing interests.

Prematurely elevating estradiol in early baboon pregnancy suppresses uterine artery remodeling and expression of extravillous placental vascular endothelial growth factor and α1β1 and α5β1 integrins

We previously showed that advancing the increase in estradiol levels from the second to the first third of baboon pregnancy suppressed placental extravillous trophoblast (EVT) invasion and remodeling of the uterine spiral arteries. Cell culture studies show that vascular endothelial cell growth factor (VEGF) plays a central role in regulating EVT migration and remodeling of the uterine spiral arteries by increasing the expression/action of certain integrins that control extracellular matrix remodeling. To test the hypothesis that the estradiol-induced reduction in vessel remodeling in baboons is associated with an alteration in VEGF and integrin expression, extravillous placental VEGF and integrin expression was determined on d 60 of gestation (term is 184 d) in baboons in which uterine artery transformation was suppressed by maternal estradiol administration on d 25-59. EVT uterine spiral artery invasion was 5-fold lower (P < 0.01), and VEGF protein expression, quantified by in situ proximity ligation assay, was 50% lower (P < 0.05) in the placenta anchoring villi of estradiol-treated than in untreated baboons. α1β1 and α5β1 mRNA levels in cells isolated by laser capture microdissection from the anchoring villi and cytotrophoblastic shell of estradiol-treated baboons were over 2-fold (P < 0.01) and 40% (P < 0.05) lower, respectively, than in untreated animals. In contrast, placental extravillous αvβ3 mRNA expression was unaltered by estradiol treatment. In summary, extravillous placental expression of VEGF and α1β1 and α5β1 integrins was decreased in a cell- and integrin-specific manner in baboons in which EVT invasion and remodeling of the uterine spiral arteries were suppressed by prematurely elevating estradiol levels in early pregnancy. We propose that estrogen normally controls the extent to which the uterine arteries are transformed by placental EVT in primate pregnancy by regulating expression of VEGF and particular integrin extracellular remodeling molecules that mediate this process.

All-trans retinoic acid can regulate the expressions of gelatinases and apolipoprotein E in glomerulosclerosis rats

Apolipoprotein E (apoE) is an important plasma protein in cholesterol homeostasis and plays a key role in the pathogenesis of glomerulosclerosis (GS). Gelatinases include matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). The abnormal expressions of gelatinases are implicated in the pathogenesis of extracellular matrix accumulation. All-trans retinoic acid (ATRA) is an import biological agent which can play a protective role against GS. We performed this investigation to explore whether ATRA could regulate the expressions of gelatinases and apoE in the glomerulus of GS rats. 120 Wistar rats were randomly divided into three groups: sham operation group (SHO), glomerulosclerosis model group without treatment (GS) and GS model group treated with ATRA (GA). The GS disease was established by uninephrectomy and adriamycin injection. At the end of 9 and 13 weeks, the relevant samples were collected and determined. Compared with GS group at 9/13 weeks, values of 24-hour urine total protein, 24-hour urine excretion for albumin, blood urea nitrogen, serum creatinine and glomerulosclerosis index, and protein expressions of apoE, transforming growth factor-βl (TGF-β1), α-smooth muscle actin, collagen-IV and fibronectin in glomerulus and mRNA expressions of apoE and TGF-β1 in renal tissue were significantly down-regulated by ATRA (each P<0.01). However, the expressions of MMP-2 and MMP-9 (mRNA, protein and activity) were enhanced in GA group than those in GS group. In conclusion, gelatinases are associated with apoE expression, and ATRA can increase the gelatinases expressions and reduce the accumulation of apoE in glomerulus of GS rats, but the detailed mechanism needs to be elucidated in the future.

Alcohol promotes breast cancer cell invasion by regulating the Nm23-ITGA5 pathway

Background

Alcohol consumption is an established risk factor for breast cancer metastasis. Yet, the mechanism by which alcohol promotes breast cancer metastases is unknown. The ability of cancer cells to invade through tissue barriers (such as basement membrane and interstitial stroma) is an essential step towards establishing cancer metastasis. In the present study, we identify and examine the roles of two genes, Nm23 and ITGA5, in alcohol-induced breast cancer cell invasion.

Methods

Human breast cancer T47D cells were treated with ethanol at various concentrations. Boyden chamber invasion assays were used to measure cellular invasive ability. The mRNA expression level of metastasis suppressor genes including Nm23 was determined by qRT-PCR. ITGA5 was identified using a qRT-PCR array of 84 genes important for cell-cell and cell-extracellular matrix interactions. Nm23 overexpression in addition to Nm23- and ITGA5 knock-down were used to determine the role of the Nm23-ITGA5 pathway on cellular invasive ability of T47D cells. Protein expression levels were verified by Western blot.

Results

Alcohol increased the invasive ability of human breast cancer T47D cells in a dose-dependent manner through the suppression of the Nm23 metastatic suppressor gene. In turn, Nm23 down-regulation increased expression of fibronectin receptor subunit ITGA5, which subsequently led to increased cellular invasion. Moreover, Nm23 overexpression was effective in suppressing the effects of alcohol on cell invasion. In addition, we show that the effects of alcohol on invasion were also inhibited by knock-down of ITGA5.

Conclusions

Our results suggest that the Nm23-ITGA5 pathway plays a critical role in alcohol-induced breast cancer cell invasion. Thus, regulation of this pathway may potentially be used to prevent the establishment of alcohol-promoted metastases in human breast cancers.

Prostasin inhibits cell invasion in human choriocarcinomal JEG-3 cells

Controlled invasion of the uterine wall by the trophoblast cells is pivotal for the successful pregnancy, and various kinds of protease are involved in this process. Serine protease prostasin has been shown to participate in the proteolytic activation of epithelial sodium channel as well as cleavage of epidermal growth factor receptor extracellular domain in human epithelial cells. Its physiological significance in human placentation has been suggested but not validated. In the present study, we found that prostasin was expressed at a relatively high level in human placenta trophoblasts in early pregnant weeks. In the in vitro cultured human choriocarcinomal JEG-3 cells, treatment with functional antibody against prostasin led to promotion in cell invasion capability, as well as increase in the production of MMP-2, MMP-26, TIMP-1, and TIMP-4. Our data indicated that this serine protease may function as an invasion suppressor in human trophoblast, participating in the invasion-restrictive regulation of trophoblasts to avoid their over-penetration into the uterine wall.

Gelatinase (MMP-2 and -9) expression profiles during gestation in the bovine endometrium

BACKGROUND

Various molecules participate in implantation and maintaining endometrial function during gestation. The remodeling of endometrial matrices is a necessary process in the coordination of gestational progress. Matrix-metalloproteinases (MMPs) like gelatinases (MMP-2 and -9) and collagenase (MMP-1) are considered to play important roles in this process. We examined MMP-2 and -9 expression using zymography, in situ hybridization, real-time PCR, and microarray analysis to clarify their roles in the bovine endometrium during gestation.

METHODS

Endometria, placentomes, and fetal membranes were collected from Japanese black cows that were killed on day 15 to 252 of gestation or during their estrous cycle. The gene expression of MMP-related molecules (mainly MMP-2 and -9) was examined using a custom-made microarray, real-time RT-PCR, and in-situ hybridization. Gelatinase activity was detected by zymography and film in situ zymography.

RESULTS

Both gelatinases were expressed in the endometrium and fetal tissues throughout gestation. MMP-2 gene expression declined with the progress of gestation, but its intensity was maintained at a high level during the peri-implantation period and increased in late gestation. The expression level of MMP-9 was stably maintained, but was relatively low compared to that of MMP-2. These gene expression patterns matched those detected by zymography for the proteins. Microarray analysis suggested that the functions of MMP-2 during implantation and the last part of gestation are closely related with those of other molecules such as tissue inhibitors of metalloproteinase (TIMP)-2, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 1, membrane type 1 (MT1)-MMP, and extracellular matrix metalloproteinase inducer (EMMPRIN).

CONCLUSION

We detected MMP-2 and -9 gene expression in the bovine endometrium and placentome throughout gestation. These data suggest that MMP-2 is one of the main endometrial remodeling factors for implantation and pre-partum in cattle. In cows, as is the case in humans and rodents, gelatinases participate in endometrial remodeling, and their activities depend on the balance of activators and inhibitors; i.e., TIMP, MT-MMP, EMMPRIN, MMP-2, MMP-9, and so on.

The Macaque Placenta—A Mini-Review

As part of an overview of the female reproductive organs in the macaque monkey, the present paper presents normal placental development. Although normally not examined in routine toxicologic pathology, the interest in the macaque as a model for reprotoxicity studies is increasing significantly. Based on different classifications, the macaque placenta belongs to the chorioallantoic, (bi)discoid, villous, deciduate, and hemochorial placental type. Within the first fourteen days after fertilization, a large number of events subsequently occur (apposition, adhesion, penetration and traversal of trophoblasts, blood vessel penetration, and development of villi). After this period, the basic placental structure has been laid down in the endometrium, and the initial communication between mother and fetus has been established. Further expansive growth of the placenta and development of anchoring villi are believed to be accomplished by continuous proliferation and migration of the trophoblasts from the trophoblastic shell. Despite the same function of human and macaque placentas, the morphologic structure and developmental timelines are different. Possible toxicological and physiological implications of these differences toward the value of macaques within reprotoxicity studies is discussed at the end of this paper. Besides a transporting role between mother and fetus, the placenta is also an endocrine organ that synthesizes a variety of hormones and cytokines. They influence ovarian and uterine physiology at the start of pregnancy and fetal and mammary physiology during gestation and around labor, respectively.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. Eveline P. C. T. de Rijk and Eric Van Esch are employed by Schering-Plough. No other competing interests were declared.

Identification of genes regulated by an interaction between alphavbeta3 integrin and vitronectin in murine decidua

The delicate balance between embryo invasion and suppression of maternal immune rejection requires a fully functional decidua in species with haemochorial placenta. Our understanding of the decidual function is very limited due to the molecular and cellular complexity involved in decidualisation. The cell adhesion molecule alpha(v)beta(3) integrin and its ligand vitronectin are upregulated in the mouse decidua during mid-pregnancy. The implications of interactions between alpha(v)beta(3) and vitronectin in regulating decidual function are not known. In the present study, interactions between alpha(v)beta(3) and vitronectin in the decidual cells of the mouse were blocked in vitro and effects on cell fate were evaluated by studying the differentially regulated genes by cDNA array and real-time polymerase chain reaction (PCR). The results indicate that expression of various genes involved in apoptotic and cell cycle pathways, as well as cytokine receptors, was deranged. Signalling through alpha(v)beta(3) seems to be important to maintain a balance between cell proliferation and apoptosis, along with the modulation of inflammatory responses of decidual cells.

Uterine stretch regulates temporal and spatial expression of fibronectin protein and its alpha 5 integrin receptor in myometrium of unilaterally pregnant rats

The adaptive growth of the uterus during pregnancy is a critical event that involves increased synthesis of extracellular matrix (ECM) proteins and dynamic remodeling of smooth muscle cell (SMC)-ECM interactions. We have previously found a dramatic increase in the expression of the mRNAs that encode fibronectin (FN) and its alpha5-integrin receptor (ITGA5) in pregnant rat myometrium near to term. Since the myometrium at term is exposed to considerable mechanical stretching of the uterine wall by the growing fetus(es), the objective of the present study was to examine its role in the regulation of FN and ITGA5 expression at late gestation and during labor. Using myometrial tissues from unilaterally pregnant rats, we investigated the temporal changes in Itga5 gene expression in gravid and empty uterine horns by Northern blotting and real-time PCR, in combination with immunoblotting and immunofluorescence analyses of the temporal/spatial distributions of the FN and ITGA5 proteins. In addition, we studied the effects of early progesterone (P4) withdrawal on Itga5 mRNA levels and ITGA5 protein detection. At all time-points examined, the Itga5 mRNA levels were increased in the gravid uterine horn, compared to the empty horn (P < 0.05). Immunoblot analysis confirmed higher ITGA5 and FN protein levels in the myometrium, associated with gravidity (P < 0.05). Immunodetection of ITGA5 was consistently high in the longitudinal muscle layer, increased with gestational age in the circular muscle layer of the gravid horn, and remained low in the empty horn. ITGA5 and FN immunostaining in the gravid horn exhibited a continuous layer of variable thickness associated directly with the surfaces of individual SMCs. In contrast to the effects of stretch, P4 does not appear to regulate ITGA5 expression. We speculate that the reinforcement of the FN-ITGA5 interaction: 1) contributes to myometrial hypertrophy and remodeling during late pregnancy; and 2) facilitates force transduction during the contractions of labor by anchoring hypertrophied SMCs to the uterine ECM.

Analysis of uteroplacental-specific molecules and their functions during implantation and placentation in the bovine

In cattle, the mechanisms underlying implantation and placental development are still unclear. Synepitheliochorial placentation in cattle is noninvasive, and thus generates limited interest in terms of degradation and remodeling of endometrial tissues. The overall purpose of this study was three-fold: (1) to examine the gene circuitry around the implantation window, (2) to understand development of the placenta during the peri-implantation period by using a uteroplacental cDNA microarray, and (3) to study the roles of molecules involved in endometrial remodeling. Bovine trophoblastic binucleate cell-specific molecules, such as pregnancy-associated glycoproteins (PAGs), placental lactogen (PL), and prolactin-related proteins (PRPs), were markedly expressed in binucleate cells (BNCs) around implantation. The expression of PRP-1 was specific to the caruncular (CAR) area of the gravid uterine horn. Gelatinases (MMP-2 and -9) in association with heparanase may be central to endometrial remodeling. In situ hybridization analyses of PAGs, PRPs, PL, and heparanase suggested that BNCs expressed these molecules simultaneously. Future studies will further investigate the specific roles of these molecules in placentogenesis. The uteroplacental cDNA microarray presented cascades of molecular signatures not only for the endometrium but also for the intricate dialogue at the level of the feto-maternal interface in cattle. Placentome morphogenesis potentially parallels the dynamic multigenic circuitry and regulates the cell cycle in the endometrium. The roles of BNCs and their secreted molecules remain an enigma, particularly with regard to the adhesion process and endometrial remodeling, which is the focus of this study.

Gene expression pattern and hormonal regulation of small proline-rich protein 2 family members in the female mouse reproductive system during the estrous cycle and pregnancy

Small proline-rich proteins (SPRR) are known to construct the cornified cell envelope (CE) in the stratified squamous epithelial cell. Their functions in the simple epithelium such as the uterine epithelium are not clear hitherto. In the present study, the mRNA expression patterns of sprr2 family members in the mouse uterus and vagina during the estrous cycle and pregnancy as well as their regulation by steroids were investigated. Using semi-quantitative RT-PCR, it was revealed that the transcripts of sprr2b, 2e and 2g genes were up-regulated in the proestrous and estrous uteri, and sprr2d was up-regulated only in the estrous uterus. In the vagina, transcription of sprr2a, 2b, 2d, 2e and 2k genes were up-regulated at the metestrous stage. Northern blot analysis demonstrated that the overall expression of sprr2 was highly up-regulated in the estrous uterus and the metestrous vagina. During pregnancy, the sprr2 mRNA in the uterus was sharply repressed from day 3 postcoitus on, and began to be induced around labor time. In situ hybridization showed that the sprr2 transcripts were localized in uterine luminal and glandular epithelial cells as well as vaginal stratified epithelial cells. In ovariectomized mice, the expression of sprr2a, 2d, 2e and 2f genes in the uterus were induced by estrogen, and the effect of estrogen on sprr2d and 2e expression could be partly abolished by progesterone. The data indicate that the sprr2 genes have unique regulation patterns in different reproductive tissues under different physiological conditions, and the encoded proteins might play diverse functions in the female reproductive system.

Expression of SWAP-70 in the uterus and feto-maternal interface during embryonic implantation and pregnancy in the rhesus monkey (Macaca mulatta)

SWAP-70 is a unique signaling protein involved in multiple processes including lymphatic cell activation, migration, adhesion, and cytoskeleton organization. Its role in reproductive system remains to be unclear. In the present study, the spatial and temporal expression of SWAP-70 in the uterus during normal menstrual cycle as well as on the feto-maternal interface during pregnancy was investigated in the rhesus monkey by in situ hybridization and immunohistochemistry. It was shown that SWAP-70 was mainly expressed in glandular epithelial cells of uterine endometrium, and the level peaked at the mid-secretory stage. At the beginning of embryonic implantation, SWAP-70 was intensely expressed at the implantation site, mainly localized in glandular and luminal epithelial cells, as well as in primary trophoblasts and epithelial plaque. High level of SWAP-70 was observed in villous cytotrophoblast (VCT), syncytiotrophoblast (ST), column cytotrophoblast, trophoblast shell, interstitial trophoblast, and endovascular trophoblast during gestational days 15-25. From gestational day 50 to term, expression of SWAP-70 decreased evidently and was restricted in VCT cells. What's more, SWAP-70 co-localized with F-actin on the feto-maternal interface, especially in highly motive extravillous trophoblasts. The data indicate that SWAP-70 may be involved in regulating motility of trophoblast cells during embryonic implantation and placentation.

Expression of nidogens in rat uterus and embryo during decidualization and implantation

The purpose of this study was to demonstrate the expression of nidogen-1 and nidogen-2 and their possible role in decidualization and implantation events during early pregnancy in rats. The tissue samples were examined from pregnant animals between gestational days 1-8 using immunocytochemistry. The uterine luminal epithelium, the glandular epithelium, and the myometrial smooth muscle cells stained strongly from gestational days 1-8 with both nidogen antibodies. At day 4 the decidual reaction areas began to appear in the stromal matrix and immunostaining of both nidogens revealed that the basement membrane of the surface epithelium was discontinuous. The differentiation of stromal cells into decidual cells was seen at gestational day 5 and both nidogens were weakly expressed in the decidualizing cells. At day 6, nidogen-2 immunoreactivity was higher in the primary decidual cells close to the embryo than nidogen-1, and during development of the decidual tissue both nidogens appeared in the endometrial stromal cells. At day 7, while expression of both nidogens declined in the primary decidual cells, their expression was markedly observed in the secondary decidual cells close to the myometrium. At day 8, expression of both nidogens was also observed to increase in the primary decidual cells. While nidogen-2 expression was seen in the parietal endoderm and primary ectoderm of the rat embryos at this developmental stage, nidogen-1 expression was only detected in the parietal endoderm. These results indicate that nidogen-1 and nidogen-2 could play important roles during embryogenesis, decidualization, and implantation in the endometrium of rat uterus.

Dynamic expression of matrix metalloproteinases (MMP-2, -9 and -14) and the tissue inhibitors of MMPs (TIMP-1, -2 and -3) at the implantation site during tubal pregnancy

Matrix metalloproteinases (MMPs) are responsible for extracellular matrix (ECM) degradation, and their functions are regulated by tissue inhibitors of MMPs (TIMPs). The evidence for the roles of MMPs and TIMPs in implantation and placentation has remained insufficient in humans, especially during the early stages. Tubal pregnancy has some similarities to normal intrauterine pregnancy and therefore may provide a unique model for implantation studies. In the present study, the expression of MMP-2, -9 and -14, and TIMP-1, -2 and -3 at the feto–maternal interface during tubal pregnancy was examined by immunohistochemistry andin situhybridization. We found that MMP-9 and TIMP-1, -2 and -3 are produced by all types of extravillous cytotrophoblast (EVCT) cells, while MMP-2 and -14 mainly exist in distal column cytotrophoblast (CCT) cells and invasive EVCT cells. Meanwhile, the intensity of MMP-14 and TIMP-1 and -2 increased along the invasive pathway toward maternal interstitium. In addition, MMP-2, -9 and -14 and TIMP-1, -2 and -3 were all detected in the villous CT (VCT) cells. Furthermore, both the mRNA level and immunoreactivity of MMP-9, TIMP-1 and -3 increased, while those of TIMP-2 decreased concurrent with the progression of pregnancy during weeks 3–9. The unique expression pattern of various MMPs and TIMPs at the feto–maternal interface suggests that they may have roles in regulating the controlled invasion of trophoblasts during implantation and placentation. Meanwhile, the study provides a better understanding of the mechanisms involved in cellular events during human pregnancy, especially at the initiation stage of implantation.