The importance of cysteine cathepsin proteases for placental development

The role of pentraxin 3 and cathepsin B levels in pregnancies complicated by preeclampsia

OBJECTIVE

The objective of this study was to compare the levels of cathepsin B and pentraxin 3 in maternal serum of pregnant women with preeclampsia in the second trimester, to ascertain the impact of these levels on maternal and fetal outcomes, and to present a comprehensive analysis of the combined effects of cathepsin B and pentraxin 3 levels.

METHODS

This prospective case-control study was conducted at Bursa Yuksek Ihtisas Training and Research Hospital between 1 January 2022 and 31 December 2022. The study included 78 pregnant women diagnosed with preeclampsia and 78 healthy pregnant women in the second trimester, between the ages of 18 and 45. Once a diagnosis of preeclampsia was established, maternal serum samples were obtained from the pregnant women prior to the initiation of any therapeutic intervention. Once all samples had been collected, the values for cathepsin B and pentraxin 3 were determined using the ELISA method.

RESULTS

The results demonstrated a statistically significant elevation in the levels of pentraxin 3 (p = 0.008) and cathepsin B (p = 0.005) in pregnancies affected by preeclampsia when compared to those deemed healthy. Moreover, pentraxin-3 (p = 0.007) and cathepsin B (p = 0.002) were found to be significantly elevated in severe preeclampsia compared to mild preeclampsia. A comparison of the groups with and without HELLP syndrome revealed no statistically significant difference between the two groups. The ROC analysis revealed that the Cathepsin B 7.04 cut-off value was statistically significantly associated with the prediction of preeclampsia in all cases, with a sensitivity of 78.2% and a specificity of 47.4% (p = 0.005, AUC = 0.631).

CONCLUSION

The levels of CB and PTX3 may be employed as biomarkers to facilitate the early diagnosis of PE during the second trimester. Furthermore, these biomarkers may prove to be promising for the prediction of PE severity.

Single cell RNA-sequencing reveals the cellular senescence of placental mesenchymal stem/stromal cell in preeclampsia

INTRODUCTION

Preeclampsia (PE) is a severe obstetric complication closely associated with placental dysfunction. Placental mesenchymal stem/stromal cells (PMSCs) modulate placental development while PE PMSCs are excessively senescent to disturb placental function. Nevertheless, the senescence mechanism of PE PMSCs remains unclear.

METHODS

PE-related single-cell RNA sequencing datasets (GSE173193), data of chip detection (GSE99007) and bulk transcriptome RNA sequencing datasets (GSE75010) were extracted from the GEO database. Firstly, the functional enrichment analyses of the differentially expressed genes (DEGs) in PMSCs were conducted. Then, the clusters of PE PMSCs were distinguished according to the expressions of senescence-related genes (SRGs) by consensus clustering analysis. Cell cycle analysis, senescence β-galactosidase, Transwell, and tube formation were conducted. Next, the expressions of the senescence-associated secretory phenotype (SASPs) were displayed. The characteristic genes of PE were screened by the least absolute shrinkage and selection operator analysis. CTSZ was suppressed in PMSCs and the cellular senescence levels were evaluated.

RESULTS

In this study, The DEGs in PMSCs were closely associated with cellular senescence. The score of SRGs was significantly higher and most of the SASPs were abnormally expressed in the senescent group. Seven characteristic genes of PE were identified, thereinto, CTSZ reduction may accelerate the senescence in PMSCs in vitro.

DISCUSSION

Combined with bioinformatic analysis and lab experiments, our study emphatically revealed the abnormal cellular senescence in PE PMSCs, in which CTSZ, one of the PE characteristic genes, regulated the cellular senescence levels in PMSCs. These findings might help to deepen the understanding of the senescence mechanism of PMSCs in PE.

Endostatin and Cystatin C as Potential Biomarkers for Early Prediction of Preeclampsia

Preeclampsia (PE) is characterized by new onset hypertension and proteinuria. Undoubtedly, some individuals do not fit precisely into this description, and it could be challenging to spot newly developed PE in females who already have hypertension or renal illness. Monitoring the disease's progression enables the optimization of delivery time while minimizing premature births. The current study explores the diagnostic benefits of serum endostatin and cystatin C in addition to serum and urinary magnesium (Mg) and fractional excretion magnesium (FEMg) for early prediction of PE. The population sample included 82 pregnant women divided into 3 groups: normal pregnancy group served as a control (n = 26), nonpreeclampsia (NPE, n = 34) group included pregnant women with one or more risk factors but did not progress to PE, and pregnant women who developed preeclampsia (PE, n = 22) group. Blood samples were withdrawn at two sampling times: at 12th to 16th and 24th to 26th weeks of gestation. Compared to normal pregnancy, results (X̅ ± SD) indicated a significant increase in serum endostatin in NPE at the first sample (10.78 ± 3.63 ng/mL) and the second sample (28.03 ± 3.79 ng/mL), while cystatin C was at the first sample (0.68 ± 0.06 mg/dL) and the second sample (0.71 ± 0.07 mg/dL). In the PE group, the serum endostatin was 18.86 ± 4.37 ng/mL at the first sampling time and 53.56 ± 9.76 ng/mL for the second sample. Serum cystatin C was also elevated in PE with X̅ ± SD equivalent to 0.73 ± 0.08 and 0.89 ± 0.08 mg/dL at the first and second samples, respectively. On the other hand, serum and urinary Mg in addition to FEMg levels did not significantly differ across the groups under study. Receiver operating characteristic (ROC) curve analysis proved that both endostatin and cystatin C could be good indicators for PE. The findings imply that measuring endostatin and cystatin C at early pregnancy and before progression to PE may be effective in detecting the likelihood of PE. Endostatin could be more precise and sensitive in assessing the probability of PE than cystatin C; however, coupling of the two parameters may be promising.

Characterization of methylation profiles in spontaneous preterm birth placental villous tissue

Preterm birth is a global public health crisis which results in significant neonatal and maternal mortality. Yet little is known regarding the molecular mechanisms of idiopathic spontaneous preterm birth, and we have few diagnostic markers for adequate assessment of placental development and function. Previous studies of placental pathology and our transcriptomics studies suggest a role for placental maturity in idiopathic spontaneous preterm birth. It is known that placental DNA methylation changes over gestation. We hypothesized that if placental hypermaturity is present in our samples, we would observe a unique idiopathic spontaneous preterm birth DNA methylation profile potentially driving the gene expression differences we previously identified in our placental samples. Our results indicate the idiopathic spontaneous preterm birth DNA methylation pattern mimics the term birth methylation pattern suggesting hypermaturity. Only seven significant differentially methylated regions fitting the idiopathic spontaneous preterm birth specific (relative to the controls) profile were identified, indicating unusually high similarity in DNA methylation between idiopathic spontaneous preterm birth and term birth samples. We identified an additional 1,718 significantly methylated regions in our gestational age matched controls where the idiopathic spontaneous preterm birth DNA methylation pattern mimics the term birth methylation pattern, again indicating a striking level of similarity between the idiopathic spontaneous preterm birth and term birth samples. Pathway analysis of these regions revealed differences in genes within the WNT and Cadherin signaling pathways, both of which are essential in placental development and maturation. Taken together, these data demonstrate that the idiopathic spontaneous preterm birth samples display a hypermature methylation signature than expected given their respective gestational age which likely impacts birth timing.

Cathepsin V: Molecular characteristics and significance in health and disease

Human cysteine cathepsins form a family of eleven proteases (B, C, F, H, K, L, O, S, V, W, X/Z) that play important roles in a considerable number of biological and pathophysiological processes. Among them, cathepsin V, also known as cathepsin L2, is a lysosomal enzyme, which is mainly expressed in cornea, thymus, heart, brain, and skin. Cathepsin V is a multifunctional endopeptidase that is involved in both the release of antigenic peptides and the maturation of MHC class II molecules and participates in the turnover of elastin fibrils as well in the cleavage of intra- and extra-cellular substrates. Moreover, there is increasing evidence that cathepsin V may contribute to the progression of diverse diseases, due to the dysregulation of its expression and/or its activity. For instance, increased expression of cathepsin V is closely correlated with malignancies (breast cancer, squamous cell carcinoma, or colorectal cancer) as well vascular disorders (atherosclerosis, aortic aneurysm, hypertension) being the most prominent examples. This review aims to shed light on current knowledge on molecular aspects of cathepsin V (genomic organization, protein structure, substrate specificity), its regulation by protein and non-protein inhibitors as well to summarize its expression (tissue and cellular distribution). Then the core biological and pathophysiological roles of cathepsin V will be depicted, raising the question of its interest as a valuable target that can open up pioneering therapeutic avenues.

Effect of vitrification on the expression of genes in porcine blastocysts derived from in vitro matured oocytes

This study aimed to examine the effect of vitrification on the expression of genes that are crucial for porcine early embryo development; cathepsin B (CTSB), growth differentiation factor 9 (GDF9), caudal type homeobox 2 (CDX2), and OCT-4, which play an important role in the maintenance of embryonic cell pluripotency. Their gene expression was investigated in expanded blastocysts (day 6-7) derived from in vitro matured oocytes. The quantitative real-time PCR method was used to assess the amount of relative specific transcripts in 20 vitrified (treatment group) and 32 fresh non-vitrified (control group) blastocysts. Vitrification was performed using 7.5% dimethyl sulfoxide (DMSO) plus 7.5% ethylene glycol (EG), and in the final step, 15% DMSO plus 15% EG and a 0.5 M sucrose solution and cryotop as a vitrification device. The blastocysts were warmed in 1 M, 0.5 M, and 0.25 M sucrose solution and kept in a culture medium for six hours before their fixation and further qPCR analysis. A significant upregulation in the targeted genes CTSB (p<.006), GDF9 (p<.04), and CDX2 (p<.003) was observed in the vitrified embryos compared to the fresh control group. Interestingly, the OCT-4 mRNA expression level was not affected by vitrification and remained comparable to that of the fresh non-vitrified embryos. In summary, the results of this pilot study showed, that vitrification induced substantial alteration in the expression of CTSB, GDF9, and CDX2 genes but did not influence the expression of OCT-4 gene in porcine in vitro derived blastocysts. Our data on the expression of developmentally important genes in vitrified porcine blastocyst may facilitate: (1) future improvements in culture conditions and/or cryopreservation protocol and (2) understanding the mechanism(s) of cryoinjuries inducing compromised post-thaw embryo development followed by the poor pregnancy outcome after blastocyst transfer.

Urinary Levels of Cathepsin B in Preterm Newborns

Increased investment in perinatal health in developing countries has improved the survival of preterm newborns, but their significant multiorgan immaturity is associated with short and long-term adverse consequences. Cathepsin B, as a protease with angiogenic properties, may be related to the process of nephrogenesis. A total of 88 neonates (60 premature children, 28 healthy term children) were included in this prospective study. We collected urine samples on the first or second day of life. In order to determine the concentration of cathepsin B in the urine, the commercially available enzyme immunoassay was used. The urinary concentrations of cathepsin B normalized with the urinary concentrations of creatinine (cathepsin B/Cr.) in newborns born at 30-34, 35-36, and 37-41 (the control group) weeks of pregnancy were (median, Q1-Q3) 4.00 (2.82-5.12), 3.07 (1.95-3.90), and 2.51 (2.00-3.48) ng/mg Cr, respectively. Statistically significant differences were found between the group of newborns born at 30-34 weeks of pregnancy and the control group (p < 0.01), and between early and late preterm babies (PTB) (p < 0.05). The group of children born at 35-36 weeks of pregnancy and the control group did not differ significantly. This result suggests that the elevated urinary cathepsin B/Cr. level may be the result of the kidneys' immaturity in preterm newborns.

Transcriptomic and ChIP-seq Integrative Analysis Reveals Important Roles of Epigenetically Regulated lncRNAs in Placental Development in Meishan Pigs

The development of the placental fold, which increases the maternal–fetal interacting surface area, is of primary importance for the growth of the fetus throughout the whole pregnancy. However, the mechanisms involved remain to be fully elucidated. Increasing evidence has revealed that long non-coding RNAs (lncRNAs) are a new class of RNAs with regulatory functions and could be epigenetically regulated by histone modifications. In this study, 141 lncRNAs (including 73 up-regulated and 68 down-regulated lncRNAs) were identified to be differentially expressed in the placentas of pigs during the establishment and expanding stages of placental fold development. The differentially expressed lncRNAs and genes (DElncRNA-DEgene) co-expression network analysis revealed that these differentially expressed lncRNAs (DElncRNAs) were mainly enriched in pathways of cell adhesion, cytoskeleton organization, epithelial cell differentiation and angiogenesis, indicating that the DElncRNAs are related to the major events that occur during placental fold development. In addition, we integrated the RNA-seq (RNA sequencing) data with the ChIP-seq (chromatin immunoprecipitation sequencing) data of H3K4me3/H3K27ac produced from the placental samples of pigs from the two stages (gestational days 50 and 95). The analysis revealed that the changes in H3K4me3 and/or H3K27ac levels were significantly associated with the changes in the expression levels of 37 DElncRNAs. Furthermore, several H3K4me3/H3K27ac-lncRNAs were characterized to be significantly correlated with genes functionally related to placental development. Thus, this study provides new insights into understanding the mechanisms for the placental development of pigs.

Serum sFlt-1, cystatin C and cathepsin B are potential severity markers in preeclampsia: a pilot study

PURPOSE

Preeclampsia is associated with abnormal invasion of the trophoblast through decidua and subsequently altered remodeling of the maternal spiral arteries and endothelial dysfunction. This phenomenon is explained by the dysregulation of various kinds of vascular factors and proteases. The purpose of this study was to compare the circulating levels of sFlt-1, cathepsin B, and cystatin C in preeclamptic and normotensive pregnancies.

STUDY DESIGN

Sixty-two pregnant women were enrolled in this prospective study. Twenty women were preeclamptic and 42 were normotensive. Serum levels of sFlt-1, cathepsin B, and cystatin C were measured using an enzyme-linked immunosorbent assay kit.

RESULTS

Circulating levels of sFlt-1, cathepsin B, and cystatin C were significantly higher in preeclamptic than in normotensive pregnant women (p < 0.001; p = 0.017; p = 0.003). Preeclamptic women with severe features demonstrated significantly higher levels of cathepsin B (p = 0.05). Serum sFlt-1 and cystatin C levels were positively correlated with elevated systolic and diastolic blood pressure. The levels of cathepsin B were positively correlated with alanine and aspartate aminotransferase. The amount of 24 h proteinuria was positively, but non-significantly correlated with sFlt-1 and cystatin C.

CONCLUSIONS

In addition to sFlt-1 levels, the serum levels of cathepsin B and cystatin C significantly change when preeclampsia develops. These markers are associated with severity markers of elevated blood pressure and liver injury in preeclampsia.

Discordant placental oxygenation and autophagy in twin anemia-polycythemia sequence (TAPS)

BACKGROUND

(Macro)autophagy is an important process of self-degradation of macromolecules and organelles that ensures cellular homeostasis and energy preservation during stressful conditions. Dysregulated placental autophagy has been implicated in a wide range of pregnancy complications. Recent studies identified hypoxia as a key regulator of trophoblast autophagy in vitro; however, its effects on placental autophagy in vivo remain incompletely understood. In this study, we evaluated the monochorionic twin anemia-polycythemia sequence (TAPS) placenta as model of discordant placental oxygenation to determine the effects of hypoxia on placental autophagy in utero.

METHODS

We performed a retrospective comparative analysis of tissue oxygenation and autophagy in anemic and polycythemic territories of TAPS placentas (N = 12). Archival tissues were subjected to immunohistochemical, immunofluorescence and Western blot analyses of carbonic anhydrase (CA) IX (hypoxia marker) and key autophagy/lysosomal markers.

RESULTS

CAIX protein levels were significantly higher in anemic twin territories than in corresponding polycythemic territories, consistent with relative tissue hypoxia. Anemic placental shares further displayed significantly higher levels of LC3I/II (autophagosome markers) and LAMP1/2 (lysosome markers), associated with upregulated expression of lysosome/autophagosome activity-associated markers, transcription factor EB and cathepsin D. The accumulation of autophagosomes and lysosomes in anemic shares was accompanied by elevated p62 protein expression, suggestive of inhibition of the downstream autophagy pathway.

CONCLUSIONS

TAPS placentas display striking intertwin discordance in tissue oxygenation and autophagic activity and may provide a suitable model for study of the interrelationship between hypoxia, autophagy, and pregnancy outcome in a monochorionic twin setting.

Evaluation of serum cathepsin B, D, and L concentrations in women with late-onset preeclampsia

Objective:

The aim of the study was to assess serum cathepsin B, D, and L concentrations in women with late-onset preeclampsia.

Materials and Methods:

One hundred forty pregnant women were enrolled in the study, of which 100 subjects were preeclamptic and 40 were healthy controls. Serum concentrations of cathepsin B, D, and L were measured and compared between the preeclamptic and control groups.

Results:

Cathepsin B and D concentrations were significantly higher in the preeclamptic group compared with the control group. There was no statistically significant difference between the groups in terms of cathepsin L concentrations. Cathepsin B concentrations were significantly higher in women with preeclampsia with severe features compared with those with preeclampsia alone.

Conclusion:

Women with late-onset preeclampsia have significantly higher serum cathepsin B and D concentrations than controls. Cathepsin B and D may be promising biomarkers in women with late-onset preeclampsia.

Placental cell death patterns exhibit differences throughout gestation in two strains of laboratory mice

Cell death is an essential physiological process required for the proper development and function of the human placenta. Although the mouse is a commonly used animal model for development studies, little is known about the extent and distribution of cell death in the mouse placenta throughout development and its physiological relevance. In the present study, we report the results of a systematic and quantitative assessment of cell death patterns in the placentae of two strains of laboratory mice commonly used for developmental studies-ICR and C57Bl/6. TUNEL staining revealed that ICR and C57Bl/6 placentae exhibited similar cell death patterns to those reported in human placentae during pregnancy, with comparatively infrequent death observed during early gestation, which increased and became more organized towards term. Interestingly, when comparing strain differences, increased cell death was observed in almost all regions of the inbred C57Bl/6 placentae compared to the outbred ICR strain. Finally, since Bcl-2 ovarian killer (Bok) has been reported to be a key player in human placental cell death, we examined its expression in murine placentae throughout gestation. Bok protein expression was observed in all placental regions and increased towards term in both strains. The results of this study indicate that although strain-specific differences in placental cell death exist, the overall rates and patterns of cell death during murine placentation parallel those previously described in humans. Thus, the murine placenta is a useful model to investigate molecular pathways involved in cell death signaling during human placentation.

Role of proteases in dysfunctional placental vascular remodelling in preeclampsia

Preeclampsia is a syndrome characterised by vascular dysfunction, impaired angiogenesis, and hypertension during pregnancy. Even when the precise pathophysiology of preeclampsia remains elusive, impaired vascular remodelling and placental angiogenesis in the placental villi and defective trophoblast invasion of the uterus are proposed as crucial mechanisms in this syndrome. Reduced trophoblast invasion leads to reduced uteroplacental blood flow and oxygen availability and increased oxidative stress. These phenomena trigger the release of soluble factors into the maternal and foetoplacental circulation that are responsible of the clinical features of preeclampsia. New blood vessels generation as well as vascular remodelling are mechanisms that require expression and activity of different proteases, including matrix metalloproteases, a-disintegrin and metalloproteases, and a-disintegrin and metalloprotease with thrombospondin motifs. These proteases exert proteolysis of the extracellular matrix. Additionally, cathepsins, a family of proteolytic enzymes, are primarily located in lysosomes but are also released by cells to the extracellular space. This review focuses on the role that these proteases play in the regulation of the uterine trophoblast invasion and the placental vascular remodelling associated with preeclampsia.

Spatiotemporal expression profile of proteases and immunological, angiogenic, hormonal and apoptotic mediators in rat placenta before and during intrauterine trophoblast migration

The gene and/or protein expression of proteases and immunological, angiogenic, hormonal and apoptotic mediators was evaluated in rat placenta before and during intrauterine trophoblast migration. The depth of interstitial and endovascular intrauterine trophoblast invasion and the immunohistochemical expression of vascular endothelial growth factor (VEGF), fetal liver kinase 1 (Flk1), interferon (IFN)-γ, migration inhibitory factor (MIF), and inducible nitric oxide synthase (iNOS; also known as nitric oxide synthase (NOS) 2) were evaluated. In addition, the expression of the Vegf, Flk1, placental growth factor (Pigf), soluble fms-like tyrosine kinase 1 (sFlt1), placental lactogen 1 (Pl1), proliferin-related protein (rPlf), placental leptin (Lep), Toll-like receptor 2 (Tlr2), Toll-like receptor 4 (Tlr4), Infg, Mif, tumour necrosis factor-α (Tnf), interleukin-10 (Il10), Nos2, caspase 3 (Casp3), Bax, Bcl2, matrix metalloproteinase 2 (Mmp2) and matrix metalloproteinase 9 (Mmp9) genes was determined by real-time reverse transcription-polymerase chain reaction. At 10 days gestation, gene expression of Tlr2, Tlr4, Tnf, Infg, Il10, Casp3, Pigf, sFlt1 and Lep (P<0.05) were higher than at 14 and/or 19 days of gestation. The beginning of intrauterine trophoblast invasion, i.e., at 14 days of gestation, coincided with higher gene and/or protein expression of MMP9, VEGF, Flk1, NOS2, MIF, BAX and rPlf compared to days 10 and 19 (P<0.05). In contrast, gene expression of Mmp2 and Pl1 was higher at the end of trophoblast invasion compared to 10 and 14 days of gestation (P<0.05). In conclusion, before intrauterine trophoblast migration, expression of TLRs and immunological and pro-apoptotic mediators is higher, whereas the beginning of trophoblast migration is characterised by higher expression of the pro-angiogenic factors NOS2 and MMP9. In contrast, MMP2 and PL1 expression is higher at the end of intrauterine trophoblast migration.

Expression of N-Acetylglucosaminyltransferase III Promotes Trophoblast Invasion and Migration in Early Human Placenta

INTRODUCTION

Trophoblast migration and invasion at the maternal-fetal interface are crucial events for normal placentation and successful pregnancy. This progress is well controlled by many placenta-specific factors. Inadequate trophoblast invasion results in poor placenta plantation or even complications such as preeclampsia. It has been shown that N-acetylglucosaminyltransferase III (GnT-III) participates in tumor invasion and metastasis as a suppressor; however, the expression of GnT-III and its role in normal pregnancy is unclear. Our objective was to characterize GnT-III expression and function during placental development and identify the underlying mechanisms.

METHODS

The expression of GnT-III in human placental tissue from the first trimester was determined by immunohistochemistry. The HTR8/SVneo cell line was used to investigate the effects of GnT-III on proliferation, apoptosis, migration/invasion, matrix metalloproteinase (MMP) 2/9 activity, and the expression of the tissue inhibitor of metalloproteinase (TIMP) 1/2 using cell 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assays, flow cytometric analysis, transwell migration/invasion assays, gelatin zymography, and Western blot, respectively. Moreover, a placental villous explant model was employed to determine its functions in placentation.

RESULTS

In the first-trimester placental tissue, GnT-III was localized within the cytotrophoblast, the syncytiotrophoblast and the trophoblast columns of human placental villi, decidual cells, and some extravillous cells in the maternal decidua. GnT-III silencing significantly inhibited HTR8/SVneo cell invasion and migration as well as extravillous explant outgrowth. The application of GnT-III siRNA significantly attenuated MMP2/9 activity and increased TIMP1/2 expression.

DISCUSSION AND CONCLUSION

GnT-III is expressed in trophoblasts during normal human pregnancy and is involved in regulating trophoblast function.

Pulse of inflammatory proteins in the pregnant uterus of European polecats (Mustela putorius) leading to the time of implantation

Uterine secretory proteins protect the uterus and conceptuses against infection, facilitate implantation, control cellular damage resulting from implantation, and supply pre-implantation embryos with nutrients. Unlike in humans, the early conceptus of the European polecat (Mustela putorius; ferret) grows and develops free in the uterus until implanting at about 12 days after mating. We found that the proteins appearing in polecat uteri changed dramatically with time leading to implantation. Several of these proteins have also been found in pregnant uteri of other eutherian mammals. However, we found a combination of two increasingly abundant proteins that have not been recorded before in pre-placentation uteri. First, the broad-spectrum proteinase inhibitor α₂-macroglobulin rose to dominate the protein profile by the time of implantation. Its functions may be to limit damage caused by the release of proteinases during implantation or infection, and to control other processes around sites of implantation. Second, lipocalin-1 (also known as tear lipocalin) also increased substantially in concentration. This protein has not previously been recorded as a uterine secretion in pregnancy in any species. If polecat lipocalin-1 has similar biological properties to that of humans, then it may have a combined function in antimicrobial protection and transporting or scavenging lipids. The changes in the uterine secretory protein repertoire of European polecats is therefore unusual, and may be representative of pre-placentation supportive uterine secretions in mustelids (otters, weasels, badgers, mink, wolverines) in general.

Activity of Proteolytic Enzymes and Level of Cystatin C in the Peripartum Period

Objectives. The aim of the study was to evaluate the activity of cathepsin B, collagenases, trypsin, and plasmin and concentration of cystatin C in serum of healthy pregnant women in peripartum period. Study Design. The study group included 45 women in uncomplicated pregnancies. Blood samples were collected in four time points. Enzyme activity was measured by spectrofluorometric method. The level of cystatin C was measured using immunonephelometric method. Results. Mean activity of cathepsin B and the level of serum cystatin C were significantly higher in the study group. Collagenase activity was significantly lower in the study group than the control group. No differences in collagenase, plasmin, and trypsin activity on each day of the peripartum period were found. Conclusion. High activity of cathepsin B and increased level of cystatin C are typical for women in late pregnancy. Those levels significantly decrease after delivery which can be associated with potential role of those markers in placental separation. The insignificant changes of cystatin C level in the peripartum period seem to exclude the possibility of using cystatin C as a marker for renal insufficiency in the peripartum period but additional research is necessary to investigate the matter further.

Bisphenol A affects placental layers morphology and angiogenesis during early pregnancy phase in mice

Bisphenol A (BPA) is a widespread endocrine disrupter mainly used in food contact plastics. Much evidence supports the adverse effects of BPA, particularly on susceptible groups such as pregnant women. The present study considered placental development - relevant for pregnancy outcomes and fetal nutrition/programming - as a potential target of BPA. Pregnant CD-1 mice were administered per os with vehicle, 0.5 (BPA05) or 50 mg kg(-1) (BPA50) body weight day(-1) of BPA, from gestational day (GD) 1 to GD11. At GD12, BPA50 induced significant degeneration and necrosis of giant cells, increased vacuolization in the junctional zone in the absence of glycogen accumulation and reduction of the spongiotrophoblast layer. In addition, BPA05 induced glycogen depletion as well as significant nuclear accumulation of β-catenin in trophoblasts of labyrinthine and spongiotrophoblast layers, supporting the activation of the Wnt/β-catenin pathway. Transcriptomic analysis indicated that BPA05 promoted and BPA50 inhibited blood vessel development and branching; morphologically, maternal vessels were narrower in BPA05 placentas, whereas embryonic and maternal vessels were irregularly dilated in the labyrinth of BPA50 placentas. Quantitative polymerase chain reaction evidenced an estrogen receptor β induction by BPA50, which did not correspond to downstream genes activation; indeed, the transcription factor binding sites analysis supported the AhR/Arnt complex as regulator of BPA50-modulated genes. Conversely, Creb appeared as the main transcription factor regulating BPA05-modulated genes. Embryonic structures (head, forelimb) showed divergent perturbations upon BPA05 or BPA50 exposure, potentially related to unbalanced embryonic nutrition and/or to modulation of genes involved in embryo development. Our findings support placenta as an important target of BPA, even at environmentally relevant dose levels.

LIMK1 regulates human trophoblast invasion/differentiation and is down-regulated in preeclampsia

Successful human pregnancy requires extensive invasion of maternal uterine tissues by the placenta. Invasive extravillous trophoblasts derived from cytotrophoblast progenitors remodel maternal arterioles to promote blood flow to the placenta. In the pregnancy complication preeclampsia, extravillous trophoblasts invasion and vessel remodeling are frequently impaired, likely contributing to fetal underperfusion and maternal hypertension. We recently demonstrated in mouse trophoblast stem cells that hypoxia-inducible factor-2 (HIF-2)-dependent Lim domain kinase 1 (LIMK1) expression regulates invasive trophoblast differentiation by modulating the trophoblast cytoskeleton. Interestingly, in humans, LIMK1 activity promotes tumor cell invasion by modulating actin and microtubule integrity, as well as by modulating matrix metalloprotease processing. Here, we tested whether HIF-2α and LIMK1 expression patterns suggested similar roles in the human placenta. We found that LIMK1 immunoreactivity mirrored HIF-2α in the human placenta in utero and that LIMK1 activity regulated human cytotrophoblast cytoskeletal integrity, matrix metallopeptidase-9 secretion, invasion, and differentiation in vitro. Importantly, we also found that LIMK1 levels are frequently diminished in the preeclampsia setting in vivo. Our results therefore validate the use of mouse trophoblast stem cells as a discovery platform for human placentation disorders and suggest that LIMK1 activity helps promote human placental development in utero.

Maternal thyroid dysfunction affects placental profile of inflammatory mediators and the intrauterine trophoblast migration kinetics

The objective of the present study was to evaluate the gene and immunohistochemical expression of inflammatory mediators involved in the immune activity and the intrauterine trophoblast migration of the placentas in hypothyroid and L-thyroxine (L-T4)-treated rats. A total of 144 adult female rats were divided equally into hypothyroid, l-T4-treated, and euthyroid (control) groups. Hypothyroidism was induced by daily administration of propylthiouracil. Rats were killed at 0, 10, 14, 15, 16, 17, 18, and 19 days of gestation. We evaluated the depth of interstitial and endovascular intrauterine trophoblast invasion and the immunohistochemical expression of interferon γ (INFy), migration inhibitory factor (MIF), and inducible nitric oxide synthase (NOS2 (iNOS)). The gene expression of Toll-like receptor 2 (Tlr2) and Tlr4, Infy, Mif, tumor necrosis factor (Tnf (Tnfα)), Il10, Nos2, matrix metalloproteinase 2 (Mmp2) and Mmp9, and placental leptin was also measured in placental disks by real-time RT-PCR. The data were analyzed using an Student-Newman-Keuls (SNK) test. Hypothyroidism reduced the endovascular and interstitial trophoblast migration, and the expression of TLR4, INFy, MIF, interleukin 10 (IL10), NOS2, MMP2 and MMP9, and placental leptin, while increased the expression of TLR2 (P<0.05). T4-treated rats not only increased the expression of IL10 and NOS2 but also reduced the expression of TNF and MIF at 10 days of gestation (P<0.05). However, at 19 days of gestation, expression of INFy and MIF was increased in T4-treated group (P<0.05). Excess of T4 also increased the gene expression of Mmp2 at 10 days of gestation (P<0.05), but reduced the endovascular trophoblast migration at 18 days of gestation (P<0.05). Hypothyroidism and excess of T4 differentially affect the immune profile and the intrauterine trophoblast migration of the placenta, and these effects are dependent on the gestational period.

The evolution of viviparity: molecular and genomic data from squamate reptiles advance understanding of live birth in amniotes

Squamate reptiles (lizards and snakes) are an ideal model system for testing hypotheses regarding the evolution of viviparity (live birth) in amniote vertebrates. Viviparity has evolved over 100 times in squamates, resulting in major changes in reproductive physiology. At a minimum, all viviparous squamates exhibit placentae formed by the appositions of maternal and embryonic tissues, which are homologous in origin with the tissues that form the placenta in therian mammals. These placentae facilitate adhesion of the conceptus to the uterus as well as exchange of oxygen, carbon dioxide, water, sodium, and calcium. However, most viviparous squamates continue to rely on yolk for nearly all of their organic nutrition. In contrast, some species, which rely on the placenta for at least a portion of organic nutrition, exhibit complex placental specializations associated with the transport of amino acids and fatty acids. Some viviparous squamates also exhibit reduced immunocompetence during pregnancy, which could be the result of immunosuppression to protect developing embryos. Recent molecular studies using both candidate-gene and next-generation sequencing approaches have suggested that at least some of the genes and gene families underlying these phenomena play similar roles in the uterus and placenta of viviparous mammals and squamates. Therefore, studies of the evolution of viviparity in squamates should inform hypotheses of the evolution of viviparity in all amniotes, including mammals.

A cathepsin B inhibitor, E-64, improves the preimplantation development of bovine somatic cell nuclear transfer embryos

Bovine somatic cell nuclear transfer (SCNT) is an important and powerful tool for basic research and biomedical and agricultural applications, however, the efficiency of SCNT has remained extremely low. In this study, we investigated the effects of cathepsin B inhibitor (E-64) supplementation of culture medium on in vitro development of bovine SCNT embryos. We initially used three concentrations of E-64 (0.1, 0.5, 1.0 μm), among which 0.5 μm resulted in the highest rate of blastocysts production after in vitro fertilization (IVF), and was therefore used for further experiments. Blastocyst development of SCNT embryos in the E-64 treatment group also increased relative to the control. Moreover, the cryosurvival rates of IVF and SCNT blastocysts were increased in E-64 treatment groups when compared with the control. On the other hand, we found that IVF and SCNT blastocysts derived from E-64-treated groups had increased total cell numbers and decreased apoptotic nuclei. Furthermore, assessment of the expression of apoptosis-related genes (Bax and Bcl-xL) in bovine IVF and SCNT blastocysts treated with E-64 by real-time RT-PCR analysis revealed suppressed expression of the pro-apoptotic gene Bax and stimulated expression of the anti-apoptotic gene Bcl-xL. Taken together, these finding indicate that addition of E-64 to embryo culture medium may have important implications for improving developmental competence and preimplantation quality in bovine IVF and SCNT embryos.

Review: the ADAM metalloproteinases - novel regulators of trophoblast invasion?

During pregnancy, the extravillous trophoblast (EVT) invades the maternal decidua and remodels spiral arteries reaching as far as the inner third of the myometrium. This process is mandatory to a successful pregnancy since EVTs regulate spiral artery remodeling to achieve maximal vasodilation and thus an adequate nutrient supply to the embryo or communicate with maternal leukocyte populations to guarantee acceptance of the allogeneic conceptus. To achieve this, EVTs undergo a remarkable and unique differentiation process, which yields different phenotypes such as proliferative cell column trophoblasts or growth-arrested, invasive interstitial or endovascular cytotrophoblasts. Matrix metalloproteinases have long been seen as imperative to trophoblast invasion because of their ability to degrade extracellular matrix and therefore allow cellular movement in foreign tissues. However, global gene expression analysis reveals that EVTs also express various members of distintegrin and metalloproteinases (ADAMs). These proteases are associated with the process of proteolytic shedding and activation of surface proteins including growth factors, cytokines, receptors and their ligands rather than extracellular matrix breakdown. While ADAM12 has been associated with chromosomal abnormalities as well as preeclampsia or intrauterine fetal growth restriction, the function of ADAMs in trophoblasts remains elusive. In this article, we review the diverse invasive trophoblast phenotypes, EVT-associated protease systems and related open questions. In addition, we examine recent information about relevant ADAM members and their putative implications for EVT biology.

Purification and characterization of a soluble calnexin from human placenta

Calreticulin (Crt) and calnexin (Cnx) are homologous endoplasmic reticulum (ER) chaperones involved in protein folding and quality control. Crt is a soluble ER luminal Mr 46 kDa protein and Cnx is a Mr 67kDa ER membrane protein. During purification of Crt from human placenta a soluble form of Cnx (sCnx) was consistently identified in a separate ion exchange chromatography peak. The sCnx was further purified and characterised. This showed that the protein had been cleaved after residue 472 (between Gln and Met), thus liberating it from the transmembrane and cytoplasmic parts of Cnx. The extraction and initial purification steps were carried out in the presence of protease inhibitors, thus ruling out that the cleavage was an artefact of the isolation procedure. This indicates that sCnx may have a physiological chaperone function similar to that of Crt.

CUL1 promotes trophoblast cell invasion at the maternal-fetal interface

Human trophoblast progenitor cells differentiate via two distinct pathways, to become the highly invasive extravillous cytotrophoblast (CTB) cells (EVT) or fuse to form syncytiotrophoblast. Inadequate trophoblast differentiation results in poor placenta perfusion, or even complications such as pre-eclampsia (PE). Cullin1 (CUL1), a scaffold protein in cullin-based ubiquitin ligases, plays an important role in early embryonic development. However, the role of CUL1 in trophoblast differentiation during placenta development has not been examined. Here we show that CUL1 was expressed in CTB cells and EVT in the first trimester human placentas by immunohistochemistry. CUL1 siRNA significantly inhibited outgrowth of extravillous explants in vitro, as well as invasion and migration of HTR8/SVneo cells of EVT origin. This inhibition was accompanied by decreased gelatinolytic activities of matrix metalloproteinase (MMP)-9 and increased expression of tissue inhibitors of MMPs (TIMP-1 and -2). Consistently, exogenous CUL1 promoted invasion and migration of HTR8/SVneo cells. Notably, CUL1 was gradually decreased during trophoblast syncytialization and CUL1 siRNA significantly enhanced forskolin-induced fusion of choriocarcinoma BeWo cells. CUL1 protein levels in human pre-eclamptic placental villi were significantly lower as compared to their matched control placentas. Taken together, our results suggest that CUL1 promotes human trophoblast cell invasion and dysregulation of CUL1 expression may be associated with PE.

Extravillous trophoblast and decidual natural killer cells: a remodelling partnership

BACKGROUND

During pregnancy, maternal uterine spiral arteries (SAs) are remodelled from minimal-flow, high-resistance vessels into larger diameter vessels with low resistance and high flow. Fetal extravillous trophoblasts (EVT) have important roles in this process. Decidual natural killer cells (dNK cells) are the major maternal immune component of the decidua and accumulate around SAs before trophoblast invasion. A role for dNK cells in vessel remodelling is beginning to be elucidated. This review examines the overlapping and dissimilar mechanisms used by EVT and dNK cells in this process and how this may mirror another example of tissue remodelling, namely cancer development.

METHODS

The published literature was searched using Pubmed focusing on EVT, dNK cells and SA remodelling. Additional papers discussing cancer development are also included.

RESULTS

Similarities exist between actions carried out by dNK cells and EVT. Both interact with vascular cells lining the SA, as well as with each other, to promote transformation of the SA. EVT differentiation has previously been likened to the epithelial-mesenchymal transition in cancer cells, and we discuss how dNK-EVT interactions at the maternal-fetal interface can also be compared with the roles of immune cells in cancer.

CONCLUSIONS

The combined role that dNK cells and EVT play in SA remodelling suggests that these interactions could be described as a partnership. The investigation of pregnancy as a multicellular system involving both fetal and maternal components, as well as comparisons to similar examples of tissue remodelling, will further identify the key mechanisms in SA remodelling that are required for a successful pregnancy.

Uterine gene expression in the live-bearing lizard, Chalcides ocellatus, reveals convergence of squamate reptile and mammalian pregnancy mechanisms

Although the morphological and physiological changes involved in pregnancy in live-bearing reptiles are well studied, the genetic mechanisms that underlie these changes are not known. We used the viviparous African Ocellated Skink, Chalcides ocellatus, as a model to identify a near complete gene expression profile associated with pregnancy using RNA-Seq analyses of uterine transcriptomes. Pregnancy in C. ocellatus is associated with upregulation of uterine genes involved with metabolism, cell proliferation and death, and cellular transport. Moreover, there are clear parallels between the genetic processes associated with pregnancy in mammals and Chalcides in expression of genes related to tissue remodeling, angiogenesis, immune system regulation, and nutrient provisioning to the embryo. In particular, the pregnant uterine transcriptome is dominated by expression of proteolytic enzymes that we speculate are involved both with remodeling the chorioallantoic placenta and histotrophy in the omphaloplacenta. Elements of the maternal innate immune system are downregulated in the pregnant uterus, indicating a potential mechanism to avoid rejection of the embryo. We found a downregulation of major histocompatability complex loci and estrogen and progesterone receptors in the pregnant uterus. This pattern is similar to mammals but cannot be explained by the mammalian model. The latter finding provides evidence that pregnancy is controlled by different endocrinological mechanisms in mammals and reptiles. Finally, 88% of the identified genes are expressed in both the pregnant and the nonpregnant uterus, and thus, morphological and physiological changes associated with C. ocellatus pregnancy are likely a result of regulation of genes continually expressed in the uterus rather than the initiation of expression of unique genes.

Concomitant lack of MMP9 and uPA disturbs physiological tissue remodeling

Urokinase-type plasminogen activator (uPA) and matrix metalloproteinase-9 (MMP9, gelatinase B) have separately been recognized to play important roles in various tissue remodeling processes. In this study, we demonstrate that deficiency for MMP9 in combination with ablation of either uPA- or tissue-type plasminogen activator (tPA)-catalyzed plasminogen activation is critical to accomplish normal gestation in mice. Gestation was also affected by simultaneous lack of MMP9 and the uPA receptor (uPAR). Interestingly, uPA-deficiency additionally exacerbated the effect of MMP9-deficiency on bone growth and an additive effect caused by combined lack in MMP9 and uPA was observed during healing of cutaneous wounds. By comparison, MMP9-deficiency combined with absence of either tPA or uPAR resulted in no significant effect on wound healing, indicating that the role of uPA during wound healing is independent of uPAR, when MMP9 is absent. Notably, compensatory upregulation of uPA activity was seen in wounds from MMP9-deficient mice. Taken together, these studies reveal essential functional dependency between MMP9 and uPA during gestation and tissue repair.

Remodelling at the maternal–fetal interface: relevance to human pregnancy disorders

In human pregnancy, successful placentation and remodelling of the uterine vasculature require the integration of a number of stages, which are crucial for a healthy pregnancy. As the demands of the developing fetus for nutrients and oxygen increase, the capacity of the maternal blood vessels to supply this must be altered radically, with deficiencies in this process implicated in a number of dangerous pregnancy complications. The complex signalling networks that regulate these tightly co-ordinated events are becoming clearer as more studies of early pregnancy are performed. It is the aim of this review to draw together our knowledge of events that occur to facilitate a successful pregnancy ranging from the preparation for implantation, through the invasion and differentiation of the trophoblast and the regulation of these processes by other cells within the decidual environment, to the active role that the trophoblast and maternal immune cells play in facilitating the remodelling of the uterine spiral arteries. The events involved in a healthy pregnancy will then be compared to aberrant placentation and remodelling, which are characteristics of many pregnancy disorders, and recent advances in detection of abnormal placental development will also be discussed.

Transient reduction of placental angiogenesis in PAI-1-deficient mice

Murine placentation is associated with the invasion of maternal endometrium by trophoblasts and an extensive maternal and fetal angiogenesis. Plasminogen activator inhibitor-1 (PAI-1) is transiently produced by spongiotrophoblasts and trophoblast giant cells at 10.5-11.5 days postcoitum (dpc). Knowing the key contribution of PAI-1 in the regulation of angiogenesis, we have now analyzed the consequence of PAI-1 deficiency on murine placentation. Morphological and quantitative computer-assisted image analysis revealed abnormal placental morphology in PAI-1-/- mice at 10.5 and 12.5 dpc. At 10.5 dpc, the genetic ablation of PAI-1 resulted in a transient reduction of both maternal and fetal vascularizations in the placenta and increased trophoblast cell density. This was associated with a poorer development of the labyrinth and an extension of the decidua. A larger spongiotrophoblast layer appeared at 12.5 dpc in PAI-1-deficient mice. Placental morphology was normalized at 14.5 dpc. Microarray analyses performed on laser capture microdissected labyrinths revealed that 46 genes were differentially expressed between the two genotypes at 10.5 dpc. However, only 11 genes were still differently modulated at 14.5 dpc, when normalization of placental morphology had taken place. This transcriptomic profiling highlighted a dysregulation in the expression of placenta-related cathepsin family members. Altogether our data provide evidence for a transient impaired placental morphology in PAI-1-deficient mice that is then normalized, leading to normal embryonic development.

Membrane-type MMPs are indispensable for placental labyrinth formation and development

The membrane-type matrix metalloproteinases (MT-MMPs) are essential for pericellular matrix remodeling in late stages of development, as well as in growth and tissue homeostasis in postnatal life. Although early morphogenesis is perceived to involve substantial tissue remodeling, the roles of MT-MMPs in these processes are only partially characterized. Here we explore the functions of 2 prominently expressed MT-MMPs, MT1-MMP and MT2-MMP, and describe their roles in the process of placental morphogenesis. The fetal portion of the placenta, in particular the labyrinth (LA), displays strong overlapping expression of MT1-MMP and MT2-MMP, which is critical for syncytiotrophoblast formation and in turn for fetal vessels. Disruption of trophoblast syncytium formation consequently leads to developmental arrest with only a few poorly branched fetal vessels entering the LA causing embryonic death at embryonic day 11.5. Through knockdown of MMP expression, we demonstrate that either MT1-MMP or MT2-MMP is crucial specifically during development of the LA. In contrast, knockdown of MT-MMP activity after LA formation is compatible with development to term and postnatal life. Taken together these data identify essential but interchangeable roles for MT1-MMP or MT2-MMP in placental vasculogenesis and provide the first example of selective temporal and spatial MMP activity required for development of the mouse embryo.

Critical growth factors and signalling pathways controlling human trophoblast invasion

Invasion of placental trophoblasts into uterine tissue and vessels is an essential process of human pregnancy and fetal development. Due to their remarkable plasticity invasive trophoblasts fulfil numerous functions, i.e. anchorage of the placenta, secretion of hormones, modulation of decidual angiogenesis/lymphangiogenesis and remodelling of maternal spiral arteries. The latter is required to increase blood flow to the placenta, thereby ensuring appropriate transfer of nutrients and oxygen to the developing fetus. Since failures in vascular changes of the placental bed are associated with pregnancy diseases such as preeclampsia or intrauterine growth restriction, basic research in this particular field focuses on molecular mechanisms controlling trophoblast invasion under physiological and pathological conditions. Throughout the years, an increasing number of growth factors, cytokines and angiogenic molecules controlling trophoblast motility have been identified. These factors are secreted from numerous cells such as trophoblast, maternal epithelial and stromal cells, as well as uterine NK cells and macrophages, suggesting that a complex network of cell types, mediators and signalling pathways regulates trophoblast invasiveness. Whereas essential features of the invasive trophoblast such as expression of critical proteases and adhesion molecules have been well characterised, the interplay between different cell types and growth factors and the cross-talk between distinct signalling cascades remain largely elusive. Similarly, key-regulatory transcription factors committing and differentiating invasive trophoblasts are mostly unknown. This review will summarise our current understanding of growth factors and signal transduction pathways regulating human trophoblast invasion/migration, as well as give insights into novel mechanisms involved in the particular differentiation process.

Cathepsin proteases have distinct roles in trophoblast function and vascular remodelling

Trophoblast giant cells are instrumental in promoting blood flow towards the mouse embryo by invading the uterine endometrium and remodelling the maternal vasculature. This process involves the degradation of the perivascular smooth muscle layer and the displacement of vascular endothelial cells to form trophoblast-lined blood sinuses. How this vascular remodelling is achieved at the molecular level remains largely elusive. Here, we show that two placenta-specific cathepsins, Cts7 and Cts8, are expressed in distinct but largely overlapping subsets of giant cells that are in direct contact with maternal arteries. We find that Cts8, but not Cts7, has the capacity to mediate loss of smooth muscle alpha-actin and to disintegrate blood vessels. Consequently, conditional ubiquitous overexpression of Cts8 leads to midgestational embryonic lethality caused by severe vascularization defects. In addition, both cathepsins determine trophoblast cell fate by inhibiting the self-renewing capacity of trophoblast stem cells when overexpressed in vitro. Similarly, transgenic overexpression of Cts7 and Cts8 affects trophoblast proliferation and differentiation by prolonging mitotic cell cycle progression and promoting giant cell differentiation, respectively. We also show that the cell cycle effect is directly caused by some proportion of CTS7 localizing to the nucleus, highlighting the emerging functional diversity of these typically lysosomal proteases in distinct intracellular compartments. Our findings provide evidence for the highly specialized functions of closely related cysteine cathepsin proteases in extra-embryonic development, and reinforce their importance for a successful outcome of pregnancy.

Proteomic analyses associate cystatin B with restricted HIV-1 replication in placental macrophages

Mononuclear phagocytes (MP; monocytes, tissue macrophages, and dendritic cells) are reservoirs, vehicles of dissemination, and targets for persistent HIV infection. However, not all MP population equally support viral growth. Such differential replication is typified by the greater ability of placental macrophages (PM), as compared to blood borne monocyte-derived macrophages (MDM), to restrict viral replication. Since cytosolic protein patterns can differentiate macrophage subtypes, we used a proteomics approach consisting of surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF), tandem mass spectrometry, and Western blots to identify differences between the uninfected and HIV-infected PM and MDM protein profiles linked to viral growth. We performed proteome analysis of PM in the molecular range of 5-20kDa. We found that a SELDI-TOF protein peak with an m/z of 11,100, which was significantly lower in uninfected and HIV-infected PM than in MDM, was identified as cystatin B (CSTB). Studies of siRNA against CSTB treatment in MDM associated its expression with HIV replication. These data demonstrate that the low molecular weight placental macrophage cytosolic proteins are differentially expressed in HIV-infected PM and MDM and identify a potential role for CSTB in HIV replication. This work also serves to elucidate a mechanism by which the placenta protects the fetus from HIV transmission.

Emerging functions of placental cathepsins

A series of tandem duplications of an ancestral cathepsin L gene has given rise to a family of eight placenta-specific cathepsins in mice. These genes are differentially regulated both spatially and temporally and thus each can perform unique placental functions. Analysis of the function and expression of these genes is yielding new insights into gene regulation and proteolytic processes in placenta, and may dissect critical placental roles of the single human functional ortholog, cathepsin L.

Expression of cathepsin P mRNA, protein and activity in the rat choriocarcinoma cell line, Rcho-1, during giant cell transformation

Lysosomal proteases perform critical functions in protein turnover and are essential for normal growth and development. Cathepsin P is a member of a newly discovered family of lysosomal cysteine proteases uniquely expressed in rodent placenta (PECs), and is closely related to human cathepsin L. Using the rat choriocarcinoma cell line model, Rcho-1, mRNA for the PECs cathepsins P, M, Q, R, 1, 2 was found to increase in expression during differentiation into a trophoblast giant cell phenotype. By contrast, expression of cathepsin L was not regulated. A specific enzyme assay was developed to show that activity of cathepsin P mirrored mRNA expression during differentiation. Cathepsin P protein co-localizes with cathepsin B, indicating that the enzyme probably functions in the endosomal-lysosomal compartment. This study demonstrates that the PEC genes produce functional proteases that can perform specific placental roles that are probably performed by broader specificity proteases in human placenta.