X-linked inhibitor of apoptosis protein expression and the regulation of apoptosis during human placental development

Apoptotic and non-apoptotic roles of caspases in placenta physiology and pathology

Caspases, a family of cysteine proteases, are pivotal regulators of apoptosis, the tightly controlled cell death process crucial for eliminating excessive or unnecessary cells during development, including placental development. Collecting research has unveiled the multifaceted roles of caspases in the placenta, extending beyond apoptosis. Apart from their involvement in placental tissue remodeling via apoptosis, caspases actively participate in essential regulatory processes, such as trophoblast fusion and differentiation, significantly influencing placental growth and functionality. In addition, growing evidence indicates an elevation in caspase activity under pathological conditions like pre-eclampsia (PE) and intrauterine growth restriction (IUGR), leading to excessive cell death as well as inflammation. Drawing from advancements in caspase research and placental development under both normal and abnormal conditions, we examine the significance of caspases in both cell death (apoptosis) and non-cell death-related processes within the placenta. We also discuss potential therapeutics targeting caspase-related pathways for placenta disorders.

Dysregulated miRNAs in recurrent miscarriage: A systematic review

Recurrent miscarriage (RM) is a complex reproductive medicine disease that affects many families. The cause of RM is unclear at this time; however, lifestyle and genetic variables may influence the process. The slight alteration in miRNA expression has enormous consequences for a variety of difficulties, one of which may be RM. The target of this systematic study was to provide a framework of the dysregulated miRNAs in RM. The Prisma guidelines were applied to perform current systematic review pertaining to articles in the seven databases. Thirty-nine papers out of 245 received fulfilled all inclusion requirements. From all the mentioned miRNAs, 40 were up-regulated (65.57 %), whereas 21 were down-regulated (34.43 %). These dysregulated miRNAs contributed to the pathophysiology of RM by influencing key pathways and processes such as apoptosis, angiogenesis, epithelial-mesenchymal transition, and the immune system. Understanding the dysregulation of miRNAs, as well as the pathways and processes that engage these miRNAs and impact disease pathogenesis, may aid in clarifying the unknown underlying mechanisms of RM and the development of novel molecular therapeutic targets and medical domains.

Expression profile of genes related to pregnancy maintenance in Dromedary Camel during the first trimester

So far, few signals involved in embryo-maternal dialogue have been identified in pregnant she-camel. Our objective was to investigate expression profiles of genes relevant to uterine extracellular matrix remodeling (ITGB4, SLCO2A1, FOS, and JUN), uterine tissue vascularization, and placental formation (VEGFA, PGF, and PDGFA), embryonic growth and development (IGF1 and PTEN), plus cell death of uterine tissue (BCL2) in early pregnant versus non-pregnant she-camels. Forty genital tracts (20 pregnant and 20 non-pregnant) and blood samples were collected from abattoirs. Total RNA was extracted from uterine tissues and qRT-PCR was conducted for candidate genes. Serum concentrations of progesterone (P4) and estradiol17-β (E2) were measured. Expression of ITGB4, FOS, and PGF genes increased (P < 0.001) in the right uterine horn of pregnant versus non-pregnant she-camels. Moreover, JUN, SLCO2A1, VEGFA, and PTEN mRNAs were up-regulated (P < 0.001) in various segments of uterine tissues in pregnant groups. The PDGFA transcript was over-expressed (P < 0.001) in both uterine horns of pregnant groups. Additionally, IGF1 was higher (P < 0.001) in the right horn and the uterine body of pregnant groups, and expression of BCL2 was increased (P < 0.001) in the pregnant uterine body. Moreover, serum concentrations of P4 were higher (P < 0.001) and E2 lower (P < 0.05) in pregnant she-camels. Taken together, the fine-tuning of genes related to implantation, matrix formation, vascularization, and placental formation is highly required for successful pregnancy in she-camels.

miR-515-5p suppresses trophoblast cell invasion and proliferation through XIAP regulation in preeclampsia

MicroRNAs (miRNAs) are non-coding small RNA molecules that can be secreted into the circulation and which exist in remarkably stable forms. Circulating miRNAs regulate numerous biological process and are aberrantly expressed in pathological conditions. Differentially expressed circulating miRNAs have received attention as potential biomarkers for many diseases. In this study, we revealed that miR-515-5p was significantly upregulated in maternal serum from preeclampsia patients in comparison to normal pregnant women. Bioinformatics prediction and a dual-luciferase reporter gene assay revealed that miR-515-5p directly targets the X-linked inhibitor of apoptosis protein (XIAP) 3'-untranslated region. In addition, the overexpression of miR-515-5p inhibited the proliferation and invasion of HTR-8/SVneo trophoblast cells. The decreased XIAP expression and reduced epithelial-mesenchymal transition (EMT) were observed in the preeclamptic placenta. Collectively, miR-515-5p may play critical roles in the pathogenesis of preeclampsia through suppression of XIAP, and serum miR-515-5p may act as a potential biomarker for preeclampsia.

Inhibitors of apoptosis: expression and regulation in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in pigs

Objective

Caspase-mediated apoptosis plays a crucial role in the regulation of endometrial and placental function in females. Caspase activity is tightly controlled by members of the inhibitors of apoptosis proteins (IAPs) family. However, the expression and regulation of IAPs at the maternal-conceptus interface has not been studied in pigs. Therefore, we determined the expression of IAP family members baculovirus IAP repeat-containing 1 (BIRC1) to BIRC6 at the maternal-conceptus interface in pigs.

Methods

We obtained endometrial tissues from pigs at various stages of the estrous cycle and pregnancy, conceptus tissues during early pregnancy, and chorioallantoic tissues during mid- to late pregnancy and analyzed the expression of IAPs. Furthermore, we determined the effects of the steroid hormones estradiol-17β (E2) and progesterone on the expression of IAPs in endometrial explant tissue cultures.

Results

During the estrous cycle, BIRC2 and BIRC5 expression varied cyclically, and during pregnancy, endometrial BIRC1, BIRC2, BIRC3, BIRC4, and BIRC5 expression varied in a stage-specific manner. Conceptus and chorioallantoic tissues also expressed IAPs during pregnancy. The BIRC2 and BIR3 mRNAs were localized to luminal epithelial cells, and BIRC4 proteins to glandular epithelial cells in the endometrium. Exposure of endometrial tissues to E2 increased the expression of BIRC6, while progesterone increased the expression of BIRC1, BIRC4, and BIRC6 in a dose-dependent manner.

Conclusion

These results indicated that IAPs were expressed in the endometrium during the estrous cycle and at the maternal-conceptus interface during pregnancy in a stage-specific manner. In addition, steroid hormones were found to be responsible for the expression of some IAPs in pigs. Together, the results suggested that IAPs may play important roles in endometrial and placental functions by regulating caspase action and apoptosis at the maternal-conceptus interface.

Effect of maternal omega-3 fatty acids and vitamin E supplementation on placental apoptotic markers in rat model of early and late onset preeclampsia

AIM

Disturbed placentation results in pregnancy complications like preeclampsia. Placental development is influenced by apoptosis during trophoblast differentiation and proliferation. Increased oxidative stress upregulates placental apoptosis. We have earlier reported increased oxidative stress, lower omega-3 fatty acids and vitamin E levels in women with preeclampsia. Current study examines effect of maternal omega-3 fatty acids and vitamin E supplementation on apoptotic markers across gestation in a rat model of preeclampsia.

MAIN METHODS

Pregnant Wistar rats were randomly assigned to control; early onset preeclampsia (EOP); late onset preeclampsia (LOP); early onset preeclampsia + omega-3 fatty acid + vitamin E supplementation (EOP + O + E) and late onset preeclampsia + omega-3 fatty acid + vitamin E supplementation (LOP + O + E) groups. Animals (Control, EOP, EOP + O + E) were sacrificed at d14 and d20 of gestation while animals (LOP, LOP + O + E) were sacrificed at d20 to collect blood and placentae. Protein and mRNA levels of apoptotic markers were analyzed by ELISA and RT-PCR respectively.

KEY FINDINGS

Protein levels of proapoptotic markers like Bcl-2 associated X-protein (BAX) (p < 0.05), caspase-8 and 3 (p < 0.01 for both) and malondialdehyde (p < 0.01) were higher only in the EOP group as compared to control. However, the antiapoptotic marker, B cell lymphoma 2 (Bcl-2) protein levels were lower in both the subtypes of preeclampsia (p < 0.01 for both).

SIGNIFICANCE

Our findings suggest that supplementation was beneficial in reducing the caspase-8 and 3 in early onset preeclampsia but did not normalize BAX and Bcl-2 levels. This has implications for reducing placental apoptosis in preeclampsia.

The Possible Involvement of miR-371a-5p Regulating XIAP in the Pathogenesis of Recurrent Pregnancy Loss

Apoptosis is an interactive and dynamic biological process involved in all phases of embryogenesis. If apoptosis dominates the trophoblast cell growth process, it will result in adverse pregnancy outcomes. X-linked inhibitor of apoptosis protein (XIAP) is a potent caspase inhibitor and an important barrier to apoptotic cell death. MicroRNAs involve in posttranscriptional gene expression regulation and apoptosis. Online sequence alignment analysis showed that there was a putative binding site of miR-371a-5p on the 3'-untranslated region (UTR) of XIAP. Thirty chorionic villi samples were collected to examine the expression of miR-371a-5p and XIAP. The dual-luciferase reporter assay was applied to determine the relationship between miR-371a-5p and XIAP by human placental choriocarcinoma cells (JEG-3) cells in vitro. After 48-hour transfection of mimics and inhibitor by JEG-3 cells in vitro, Western blotting was used to, respectively, detect the protein expression levels of XIAP and caspase-3. Flow cytometry was used to validate the apoptosis ratio of transfection. The expression of miR-371a-5p and XIAP in recurrent pregnancy loss was greatly decreased. The results from the luciferase reporter assay strongly suggested binding of the XIAP 3'-UTR by miR-371a-5p. Apoptosis percentage of miR-371a-5p mimic was significantly greater than that of normal control. However, apoptosis percentage of miR-371a-5p inhibitor was significantly lower than that of normal control. A significant decrease in luciferase activity was observed in miR-371a-5p mimics-transfected JEG-3 cells compared with controls. These findings provide the evidence that miR-371a-5p is one of the regulating factors according to apoptosis pathway of XIAP-caspase-3 and may be involved in the pathogenesis of recurrent pregnancy loss.

Lentivirus-mediated miR-23a overexpression induces trophoblast cell apoptosis through inhibiting X-linked inhibitor of apoptosis

Preeclampsia (PE) is a pregnancy-specific disorder representing a major cause of maternal and perinatal morbidity and mortality. MicroRNAs (miRNAs) have emerged as critical regulators in PE. However, the precise role of miRNAs in PE remains poorly understood. In this study, we aimed to investigate the potential role of miR-23a and the underlying mechanism in regulating trophoblast cell apoptosis. We found a significant increase of miR-23a expression in placental tissues from PE patients. Lentivirus-mediated miR-23a overexpression significantly induced apoptosis in trophoblast cells in vitro. X-linked inhibitor of apoptosis (XIAP) was identified as a target gene of miR-23a by bioinformatics analysis and dual-luciferase reporter assay. Overexpression of miR-23a significantly inhibited XIAP expression. Knockdown of XIAP also induced trophoblast cell apoptosis. Moreover, restoration of XIAP expression significantly abolished the miR-23 overexpression-induced trophoblast cell apoptosis. Taken together, our study demonstrates that miR-23a induces trophoblast cell apoptosis by inhibiting XIAP, which may contribute to PE. Our findings provide novel insights into understanding the pathogenesis of PE and suggest a potential therapeutic target in PE.

Insights into dovetailing GTD and Cancers

Gestational trophoblastic diseases (GTD) encompass a group of placental tumors which mostly arise due to certain fertilization defects, resulting in the over-proliferation of trophoblasts. The major characteristic of this diseased state is that β-hCG rises up manifold than that is observed during pregnancy. The incidence of GTD when analyzed on a global scale, figures out that there is a greater risk in South-East Asia, the reason of which remains unclear. An insight into any possible correlation of GTD incidence with cancers, other than choriocarcinoma, is being attempted here. Also, we review the recent developments in research on the molecular etiopathology of GTD. This review would render a wider eye towards a new paradigm of thoughts to connect GTD and breast cancer, which has not been into the picture till date.

Decreased activation of placental mTOR family members is associated with the induction of intrauterine growth restriction by secondhand smoke in the mouse

Cigarette smoke is known to be a risk for the development of intrauterine growth restriction (IUGR). Our objective was to assess the effects of secondhand smoke (SHS) during pregnancy and to what extent it regulates the activation of mTOR family members and murine trophoblast invasion. Mice were treated to SHS for 4 days. Placental and fetal weights were recorded at the time of necropsy. Immunohistochemistry was used to determine the level of placental trophoblast invasion. Western blots were utilized to assess the activation of caspase 3, XIAP, mTOR, p70 and 4EBP1 in treated and control placental lysates. As compared to controls, treated animals showed: (1) decreased placental (1.4-fold) and fetal (2.3-fold) weights (p < 0.05); (2) decreased trophoblast invasion; (3) significantly decreased active caspase 3 (1.3-fold; p < 0.02) and increased active XIAP (3.6-fold; p < 0.05) in the placenta; and (4) a significant decrease in the activation of placental mTOR (2.1-fold; p < 0.05), p70 (1.9-fold; p < 0.05) and 4EBP1 (1.3-fold; p < 0.05). Confirmatory in vitro experiments revealed decreased trophoblast invasion when SW71 cells were treated with 0.5 or 1.0 % cigarette smoke extract (CSE). Similar to primary smoking, SHS may induce IUGR via decreased activation of the mTOR family of proteins in the placenta. Increased activation of the placental XIAP protein could be a survival mechanism for abnormal trophoblast cells during SHS exposure. Further, CSE reduced trophoblast invasion, suggesting a direct causative effect of smoke on susceptible trophoblast cells involved in IUGR progression. These results provide important insight into the physiological consequences of SHS exposure and smoke-mediated placental disease.

Apoptosis in the Trophoblast—Role of Apoptosis in Placental Morphogenesis

Villous trophoblast is the epithelial cover of the placental villous tree and comes in direct contact with maternal blood. The turnover of villous trophoblast includes proliferation and differentiation of cytotrophoblast, syncytial fusion of cytotrophoblast with the overlying syncytiotrophoblast, differentiation in the syncytiotrophoblast, and finally extrusion of apoptotic material into the maternal circulation. In recent years, it has become clear that apoptosis is a normal constituent of trophoblast turnover and the release of apoptotic material does not lead to an inflammatory response of the mother. During preeclampsia there seems to be an altered balance between proliferation and apoptosis of villous trophoblast leading to a dysregulation of the release from the syncytiotrophoblast. The normal apoptotic release may be reduced in favor of a necrotic release. Since apoptosis is still ongoing in the syncytiotrophoblast, a necrotic release of intrasyncytial and partly apoptotic material lead us to call this type of release "aponecrotic shedding." In this situation, cell-free components such as G-actin and DNA freely floating in maternal blood may trigger damage to the maternal endothelium, thereby triggering preeclampsia. This review highlights the importance of the apoptosis cascade in permitting normal physiologic turnover of villous trophoblast. It will demonstrate the participation of initial stages of this cascade within the cytotrophoblast and of the execution stages within the syncytiotrophoblast. Moreover, this review presents hypotheses of how dysregulation of the apoptosis cascade may be linked to endothelial dysfunction of the maternal vasculature in preeclampsia.

Microduplication of chromosome Xq25 encompassing STAG2 gene in a boy with intellectual disability

Whole-genome microarray analysis is proven to be useful in the identification of submicroscopic copy number imbalances in families with intellectual disabilities. The first case of Xq25 duplication was identified using genome-wide array comparative genomic hybridization (array-CGH) in a 24-year-old patient with a syndromic intellectual disability. We report a 4-year-old boy with a de novo 591 kb duplication at Xq25. The duplication was first detected by a CytoScan HD array platform (Affymetrix, USA) and was confirmed by real-time quantitative PCR (qPCR) of the STAG2 gene, and by fluorescence in situ hybridization (FISH). The patient had clinical features partially consistent with published cases, including an intellectual disability and speech delay. The identification of this additional patient and a detailed analysis of duplications identified in other patient cohorts and absent in normal individuals support the existence of a rare pathological microduplication at Xq25 that encompasses STAG2.

X-linked inhibitor of apoptosis protein negatively regulates neuronal differentiation through interaction with cRAF and Trk

X-linked Inhibitor of apoptosis protein (XIAP) has been classically identified as a cell death regulator. Here, we demonstrate a novel function of XIAP as a regulator of neurite outgrowth in neuronal cells. In PC12 cells, XIAP overexpression prevents NGF-induced neuronal differentiation, whereas NGF treatment induces a reduction of endogenous XIAP levels concomitant with the induction of neuronal differentiation. Accordingly, downregulation of endogenous XIAP protein levels strongly increases neurite outgrowth in PC12 cells as well as axonal and dendritic length in primary cortical neurons. The effects of XIAP are mediated by the mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinases (ERKs) pathway since blocking this pathway completely prevents the neuritogenesis mediated by XIAP downregulation. In addition, we found that XIAP binds to cRaf and Trk receptors. Our results demonstrate that XIAP plays a new role as a negative regulator of neurotrophin-induced neurite outgrowth and neuronal differentiation in developing neurons.

Is apoptosis a regulatory mechanism during early canine pregnancy?

Fas is a membrane-bound protein which upon activation causes programmed cell death. Fas ligand (FasL) binds Fas on target cells. Both these factors are known to regulate apoptosis at implantation in different species and thus might be involved in the regulation of implantation in dogs. The aim of the study was to assess the expression of Fas and FasL in canine uterine tissue throughout pregnancy as well as in pre-implantation embryos using RT-PCR and RT-qPCR. Uterine tissues was collected from of 21 healthy pregnant bitches (group I: days 10-12, n = 5; group II: days 18-25, n = 6; group III: days 28-45, n = 6) and from 4 non-pregnant bitches (controls: days 10-12). Pregnancy stage was determined by days after mating, that is, 2-3 days after ovulation as determined by vaginal cytology and progesterone measurement. After ovariohysterectomy, uteri from group I bitches were flushed with PBS and the embryos washed and stored frozen at -80°. Tissues from the other groups were taken from the implantation and placentation sites, respectively, covered with Tissue Tek(®) and frozen at -80°. Extraction of RNA was performed with Trizol Reagent and RT-qPCR using SYBR green probes. In pre-implantation embryos, only FasL but not Fas could be detected. In all tissues from pregnant and non-pregnant bitches, both parameters were detectable. Before implantation (group I) expression of FasL resembled that of non-pregnant bitches in early dioestrus and decreased significantly during implantation and thereafter (p < 0.05). Expression of Fas did not change significantly until day 45. The relative expression of Fas exceeded that of FasL at each stage investigated, which is comparable to observations of other species; however, high standard deviations indicate high individual differences. These preliminary results point towards a regulatory function of the Fas/FasL system during early canine pregnancy.

Reduced expression of survivin, the inhibitor of apoptosis protein correlates with severity of preeclampsia

INTRODUCTION

Preeclampsia is a major complication of pregnancy affecting maternal and fetal health. Although the pathogenesis of preeclampsia is unclear, it is believed that trophoblast apoptosis plays an important role in the pathogenesis of preeclampsia during pregnancy. Survivin is a member of the inhibitor of apoptosis protein family that uniquely promotes trophoblast proliferation. In this study we investigated the alteration of survivin levels during pregnancy and compared the survivin protein and mRNA between preeclampsia and normal pregnancy.

METHODS

The mRNA level of survivin in first, second and third trimester placentae was measured by Real-time PCR. The expression of survivin in preeclamptic placentae (including severe and mild preeclampsia) and in age-matched normal placentae was measured by immunohistochemistry. The mRNA levels of survivin in preeclamptic or normal placentae were measured by Real-time PCR.

RESULTS

The mRNA level of survivin was significantly reduced throughout gestation. The mRNA level of survivin in preeclamptic placentae was significantly reduced compared to that in normal placenta. The mRNA level of survivin in severe preeclamptic placentae was further significantly reduced compared to that in mild preeclamptic placentae. In addition, survivin was expressed on syncytiotrophoblasts and cytotrophoblasts and the expression of survivin was significantly decreased in preeclamptic placenta compared to that in normal placenta (p=0.01). Furthermore the expression of survivin in severe preeclamptic placentae was significantly lower than that in mild preeclamptic placentae.

CONCLUSION

Our current data suggests lower placental expression of survivin may be associated with the severity of preeclampsia.

Increased placental XIAP and caspase 3 is associated with increased placental apoptosis in a baboon model of maternal nutrient reduction

OBJECTIVE

Our objective was to determine signaling molecules and apoptosis rate in the term placenta of a baboon model of maternal nutrient reduction (MNR).

STUDY DESIGN

Female baboons were fed ad libitum for controls (n = 7) or 70% of control baboon diet (MNR; n = 6) from 30-165 days of gestation with necropsy at 165 days of gestation. Placental tissues were collected and fixed for immunohistochemistry or snap frozen to measure extracellular signal-regulated kinases, protein kinase B, JUN NH(2)-terminal kinase, X-linked inhibitor of apoptosis protein, and caspase 3. Placental villous apoptosis was determined by terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling and cytokeratin 18 cleavage.

RESULTS

Compared with the control placentas, MNR placentas demonstrated reduced placental weight (P < .02), decreased phospho (p)-ERK (P < .04), increased placental villous apoptosis (P < .001), increased villous cytokeratin 18 cleavage, increased X-linked inhibitor of apoptosis protein (P < .007), and increased active caspase 3 (P < .02).

CONCLUSION

We conclude that placental apoptosis is increased in this baboon model of MNR at term and that the increase in X-linked inhibitor of apoptosis protein may be a protective mechanism against this apoptosis.

Analysis of inhibitor of apoptosis protein family expression during mammary gland development

Background

Inhibitors-of-Apoptosis-Proteins (IAPs) are an evolutionarily conserved family of proteins capable of regulating several facets of apoptosis. IAPs are frequently dysregulated in cancer, but their role in the regulation of apoptosis during developmental processes is not fully understood. Here we examined the expression of IAPs during the post-natal development of the mouse mammary gland, which is a tissue that exhibits a profound induction of apoptosis during involution.

Results

Six out of eight mammalian IAP family members are expressed in the mammary gland. Notably, quantitative PCR and immunoblotting revealed that XIAP, c-IAP1 and c-IAP2 are down-regulated in pregnancy and lactation, and prior to the onset of involution. In cultured mammary epithelial cells (MECs), XIAP levels decreased in response to inhibition of growth factor signalling. Maintaining XIAP levels in MECs by expressing exogenous XIAP protected them from all apoptotic stimuli tested.

Conclusions

These data suggest that the developmental regulation of IAP expression in vivo contributes to naturally occurring programmes of cell death.

AKT controls human first trimester trophoblast cell sensitivity to FAS-mediated apoptosis by regulating XIAP expression

The PIK3/AKT pathway plays an important role in both the inhibition of the apoptotic cascade and the promotion of cell growth and proliferation. Multiple apoptosis-related targets of phosphatidylinositide 3-kinase (PIK3) and protein kinase B (AKT) have been identified, including the antiapoptotic protein XIAP. By phosphorylating XIAP, AKT was previously shown to prevent the ubiquitinization and degradation of XIAP. First-trimester trophoblast cells express high levels of XIAP, which protects them from certain apoptotic stimuli. In this study, we determine that the inhibition of the PIK3/AKT pathway induces XIAP inactivation and the activation of caspase 3 in first-trimester trophoblast cells. Using a specific AKT inhibitor and a XIAP mutant construct, which mimics the AKT phosphorylated form of XIAP, we also demonstrate that these effects are dependent on the phosphorylation of XIAP by AKT. Finally, we show that the selective inhibition of AKT renders normally resistant first-trimester trophoblast cells sensitive to FAS-mediated apoptosis by regulating XIAP expression. Our findings may provide a link between AKT, XIAP, and the regulation of the FAS apoptotic cascade in first-trimester trophoblast cells and contribute to our current knowledge of the molecular mechanisms mediating normal trophoblast physiology during pregnancy.

Expression and prognostic significance of Livin in the progression of bladder cancer

It has been suggested that progression of bladder transitional cell cancer (BTCC) may be regulated at the molecular level by a typical pattern of expression of genes involved in apoptosis. Recently Livin, belonging to the inhibitors of apoptosis (IAP) family, has been found to be expressed in most solid tumors, where its expression is suggested to have clinical significance. In order to explore the significance of Livin expression in the development of BTCC, immunohistochemistry and RT-QPCR were used to detect the expression of Livin mRNA in tumor tissues and adjacent normal tissues of 30 cases of BTCC. The results showed that the positive rate of Livin expression in adjacent normal tissues and tumor tissues was 0 and 60% (18/30) respectively. The-Delta Delta CT value of Livin in BTCC tissues was 8.0454 (7.4264-8.6644) times of that in adjacent normal tissues. The expression of Livin mRNA had no correlation with tumor pathological grades and clinical stages. It was suggested that there was weak expression of Livin mRNA in adjacent normal tissues, but strong in tumor tissues.

Live and let die - regulation of villous trophoblast apoptosis in normal and abnormal pregnancies

Since 1995 the number of publications investigating apoptosis in villous trophoblast has increased exponentially. This scientific interest is in part due to observations that this specialised form of cell death is increased in pregnancy complications such as pre-eclampsia and intra-uterine growth restriction. In addition, apoptosis is described in normal villous trophoblast and elements of the apoptotic machinery are involved in the fusion between cytotrophoblast and the overlying multinucleate syncytiotrophoblast. The increase in descriptions of apoptotic cell death in villous trophoblast has been accompanied by investigations of regulators of apoptosis. It is anticipated that understanding the regulation of apoptosis in villous trophoblast may provide new insights into placental pathologies. This review describes current knowledge regarding the expression and function of these regulators in villous trophoblast, both in normal and complicated pregnancies.

Fetal growth restriction triggered by polycyclic aromatic hydrocarbons is associated with altered placental vasculature and AhR-dependent changes in cell death

Maternal cigarette smoking is considered an important risk factor associated with fetal intrauterine growth restriction (IUGR). Polycyclic aromatic hydrocarbons (PAHs) are well-known constituents of cigarette smoke, and the effects of acute exposure to these chemicals at different gestational stages have been well established in a variety of laboratory animals. In addition, many PAHs are known ligands of the aryl hydrocarbon receptor (AhR), a cellular xenobiotic sensor responsible for activating the metabolic machinery. In this study, we have applied a chronic, low-dose regimen of PAH exposure to C57Bl/6 female mice before conception. This treatment caused IUGR in day 15.5 post coitum (d15.5) fetuses and yielded abnormalities in the placental vasculature, resulting in significantly reduced arterial surface area and volume of the fetal arterial vasculature of the placenta. However, examination of the small vasculature within the placental labyrinth of PAH-exposed dams revealed extensive branching and enlargement of these vessels, indicating a possible compensatory mechanism. These alterations in vascularization were accompanied by reduced placental cell death rates, increased expression levels of antiapoptotic Xiap, and decreased expression of proapoptotic Bax, cleaved poly(ADP-ribose) polymerase-1, and active caspase-3. AhR-deficient fetuses were rescued from PAH-induced growth restriction and exhibited no changes in the labyrinthine cell death rate. The results of this investigation suggest that chronic exposure to PAHs is a contributing factor to the development of IUGR in human smokers and that the AhR pathway is involved.

Decreased placental X-linked inhibitor of apoptosis protein in an ovine model of intrauterine growth restriction

OBJECTIVE

The objective of the study was to assess placental apoptosis at both midgestation and near term in an ovine model of placental insufficiency (PI) and intrauterine growth restriction (IUGR).

STUDY DESIGN

At 40 days' gestational age (dGA), 2 groups of 4 ewes were exposed to hyperthermic conditions for either 55 days or 80 days to induce IUGR with necropsies at 95 (midgestation) and 130 dGA (term = 140 dGA), respectively. Blood gases were assessed and placental tissues obtained for apoptosis analyses.

RESULTS

PI-IUGR pregnancies showed: (1) a decrease in fetal O(2) saturation and pO(2) (P < .04), (2) an increase in placental villi apoptosis (P < .05) at midgestation and near term, and (3) a decrease of cotyledon X-linked inhibitor of apoptosis protein (XIAP) at both gestational periods (P < .04) with no differences in caruncle XIAP protein.

CONCLUSION

Placental villous apoptosis is increased at midgestation and near term in our ovine model of IUGR, and this increase is associated with a significant decrease in XIAP protein in the cotyledon of IUGR animals.

Coelomic cells show apoptosis via Fas/FasL system: a comparative study between healthy human pregnancies and missed miscarriages

BACKGROUND

The Fas/Fas ligand (FasL) system represents one of the main apoptotic pathways controlling placental apoptosis throughout gestation. In the current study, we have examined the Fas/FasL protein expression and the apoptotic incidents of coelomic cells, amniotic cells and trophoblastic tissue in first trimester human pregnancies and missed miscarriages (MM).

METHODS

Protein expression was determined by immunofluoresence, western blotting analysis, immunohistochemistry and indirectly by RT-PCR, whereas apoptotic cell death was assessed by in situ DNA fragmentation analysis.

RESULTS

Coelomic cells express Fas/FasL proteins, can undergo apoptosis and were the only cells in which apoptosis, Fas protein expression and FasL protein expression were accordingly increased along with gestational age (P = 0.001, P = 0.008; P = 0.012, respectively). In contrast, amniotic cells and trophoblast showed a consistency in the expression levels of Fas/FasL proteins in healthy pregnancies. MM were accompanied by increased Fas/FasL protein expression in all examined samples (P < 0.001). The increase of Fas/FasL protein expression was accompanied by proportional increase of apoptotic incidents among the coelomic cell population (P = 0.023, P = 0.009, respectively), whereas amniotic cells and trophoblast appeared to be resistant to Fas-induced apoptosis. The lowest expression of Fas/FasL proteins and the minimum occurrence of apoptotic incidents were detected in the trophoblast.

CONCLUSIONS

These data suggest that there is a different regulation and function of the Fas/FasL system in early human pregnancies. Aberration of the Fas-mediated apoptosis may represent one of the execution-step necessary for pregnancy loss in MM cases.

Formation of Syncytial Knots is Increased by Hyperoxia, Hypoxia and Reactive Oxygen Species

The syncytiotrophoblast contains aggregates of nuclei termed syncytial knots. Increased numbers of syncytial knots have been reported in placentae of pregnancies complicated by pre-eclampsia and fetal growth restriction (FGR). As oxidative stress has been implicated in the pathophysiology of these disorders, we hypothesised that the formation of syncytial knots may be induced by exposure to hypoxia, hyperoxia or reactive oxygen species (ROS). We assessed both the number and morphology of syncytial knots induced by culture in hypoxia, hyperoxia and with ROS. We also investigated whether the presence of syncytial knots in normal tissue was associated with a down-regulation of anti-apoptotic proteins Bcl-2, Mdm2, XIAP and survivin. Using our measurement system we describe an increased number of syncytial knots when tissue is cultured in hypoxia, hyperoxia or in the presence of ROS. The morphology of these syncytial knots was similar to those seen in vitro, although the nuclei from cultured placental explants were morphologically more homogenous, had fewer nuclear pores, and a higher heterochromatin:euchromatin ratio. Despite the apoptotic appearances of nuclei we did not detect a loss of anti-apoptotic proteins in the region of syncytial knots. We conclude that the increased number of syncytial knots in placentae from pregnancies complicated by pre-eclampsia and FGR can be replicated in vitro by ROS or hypoxia, supporting their involvement in the pathogenesis of these conditions.

XAF1 mediates tumor necrosis factor-alpha-induced apoptosis and X-linked inhibitor of apoptosis cleavage by acting through the mitochondrial pathway

Tumor necrosis factor-alpha (TNF-alpha) and Fas ligand induce apoptosis by interacting with their corresponding membrane-bound death receptors and activating caspases. Since both systems share several components of the intracellular apoptotic cascade and are expressed by first trimester trophoblasts, it is unknown how these cells remain resistant to Fas ligand while sensitive to TNF-alpha. XAF1 (X-linked inhibitor of apoptosis (XIAP)-associated factor 1) is a proapoptotic protein that antagonizes the caspase-inhibitory activity of XIAP. Here, we demonstrated that XAF1 functions as an alternative pathway for TNF-alpha-induced apoptosis by translocating to the mitochondria and promoting XIAP inactivation. In addition, we showed that the overexpression of XAF1 sensitized first trimester trophoblast cells to Fas-mediated apoptosis. Furthermore, we also determined that the differential expression of XAF1 in first and third trimester trophoblast cells was due to changes in XAF1 gene methylation. Our results establish a novel regulatory pathway controlling trophoblast cell survival and provide a molecular mechanism to explain trophoblast sensitivity to TNF-alpha and the increased number of apoptotic trophoblast cells observed near term. Aberrant XAF1 expression and/or localization may have consequences for normal pregnancy outcome.

Neonatal porcine islets exhibit natural resistance to hypoxia-induced apoptosis

BACKGROUND

Despite the success of the Edmonton protocol for human islet transplantation, an alternate source of islet tissue must be developed if beta-cell replacement therapy is to see widespread application. Neonatal porcine islets (NPI) represent one potential source of tissue. When human or rodent islets are transplanted, the majority of cells undergo hypoxia-induce apoptosis soon after the grafts are placed in the recipient. In the present study, we investigated whether NPI were similarly sensitive to hypoxia.

METHODS

NPI were exposed to hypoxia and hypoxia/reoxygenation using an in vitro hypoxic chamber. Afterwards, viability, frequency of apoptosis, and beta-cell function were evaluated. NPI and adult porcine islets were transplanted into chemically diabetic, immunodeficient mice and graft apoptosis was assessed 24 hours and seven days posttransplant.

RESULTS

NPI demonstrated a remarkable capacity to resist apoptosis and maintain insulin secretion despite severe stresses such as hypoxia/reoxygenation. One day after transplantation, NPI grafts showed limited apoptosis, confined to rare strongly insulin positive cells. In contrast, adult porcine islet grafts underwent widespread apoptosis. Western blotting revealed that NPI express high levels of at least one potent endogenous antiapoptotic protein (XIAP).

CONCLUSIONS

The majority of cells within transplanted human islets undergo apoptosis soon after portal infusion. In contrast, NPI have the capacity to resist this early posttransplant apoptosis, with likely reduced antigen release and diminished immune stimulation. NPI appear to contain a population of insulin-low to insulin-negative pre-beta-cells, which are resistant to hypoxia-induced apoptosis and still capable of differentiating into mature beta-cells.

Apoptosis and its role in the trophoblast

During early placentation the trophoblast of the human placenta differentiates to the villous and extravillous types of trophoblast. Villous trophoblast provides the epithelial cover of the placental villous trees in direct contact to maternal blood. Extravillous trophoblast invades maternal uterine tissues thus directly contacting maternal stromal and immune cells. A subset of extravillous trophoblast, endovascular trophoblast initially occludes the lumen of spiral arteries and comes into direct contact with maternal blood. In recent years apoptosis has been described in both types of trophoblast and the importance of this cascade for the normal function of the trophoblast has become obvious. One feature of serious conditions such as preeclampsia or intrauterine growth restriction is changes in apoptosis regulation in villous and/or extravillous trophoblast resulting in altered trophoblast invasion and/or shedding into the maternal circulation. This review summarizes recent findings on trophoblast apoptosis in normal and pathologic pregnancies.

The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy

Apoptosis is important for normal placental development, but it may also be involved in the pathophysiology of pregnancy-related diseases. Normal placental development is dependent upon the differentiation and invasion of the trophoblast, the main cellular component of the placenta. Trophoblast apoptosis increases in normal placentas as gestation proceeds, and a greater incidence of trophoblast apoptosis has been observed in pregnancies complicated by preeclampsia or intrauterine growth retardation (IUGR). In response to different stimuli, apoptosis may be initiated extrinsically by the death receptor pathway or intrinsically by the mitochondrial pathway. The central executioners of apoptosis are the caspases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By inhibiting caspase activation, several endogenous inhibitors, including flice-like inhibitory proteins (FLIPs), inhibitors of apoptosis (IAPs), and antiapoptotic Bcl-2 family members, can prevent further propagation of the death signal. Macrophages present at the maternal-fetal interface may also contribute to trophoblast survival by removing apoptotic cells and producing cytokines and growth factors, which influence the progression of the apoptotic cascade. This review focuses on the role of apoptosis in trophoblast development and differentiation, the molecular mechanisms by which normal trophoblast apoptosis can occur, and how it is regulated to prevent excessive trophoblast apoptosis and possible pregnancy complications.

Molecular mechanisms of trophoblast survival: From implantation to birth

Fetal development depends upon a coordinated series of events in both the embryo and in the supporting placenta. The initial event in placentation is appropriate lineage allocation of stem cells followed by the formation of a spheroidal trophoblastic shell surrounding the embryo, facilitating implantation into the uterine stroma and exclusion of oxygenated maternal blood. In mammals, cellular proliferation, differentiation, and death accompany early placental development. Programmed cell death is a critical driving force behind organ sculpturing and eliminating abnormal, misplaced, nonfunctional, or harmful cells in the embryo proper, although very little is known about its physiological function during placental development. This review summarizes current knowledge of the cell death patterns and molecular pathways governing the survival of cells within the blastocyst, with a focus on the trophoblast lineage prior to and after implantation. Particular emphasis is given to human placental development in the context of normal and pathological conditions. As molecular pathways in humans are poorly elucidated, we have also included an overview of pertinent genetic animal models displaying defects in trophoblast survival.

Fas ligand expression by maternal decidual cells is negatively correlated with the abundance of leukocytes present at the maternal–fetal interface

The abundance of leukocytes at the maternal-fetal interface could influence the fate and invasion of extravillous trophoblasts. However, the mechanism(s) involved in determining the number of leukocytes present at the maternal-fetal interface as well as the nature of the interactions between invading fetal trophoblasts, maternal leukocytes and decidual cells are not well understood. In the present studies, we examined Fas ligand (FasL)/Fas expression at the maternal-fetal interface in human placental tissues of early pregnancy by immunohistochemistry. The types of cells and their localization were also characterized by specific cell markers (cytokeratin, vimentin and CD45 for trophoblast, decidual cells and leukocytes, respectively). The cells undergoing apoptosis and specific apoptotic trophoblasts were detected by TUNEL assay and M30 cytoDEATH immunostaining, respectively. Using single or double immunostaining, we found that FasL expression in decidual cells was negatively correlated with the number of Fas-expressing leukocytes in the same region. Furthermore, the density of leukocytes had an inverse relationship with the number of interstitial trophoblasts present in the same area. We observed also that extravillous trophoblasts are viable despite expressing Fas and being in close proximity to decidual cell-derived FasL. These data support our hypothesis that maternal decidual cell-derived FasL may be involved in preventing the recruitment of Fas-bearing leukocytes at the maternal-fetal interface through apoptosis induction by Fas/FasL interaction, thereby promoting trophoblast invasion.

Temporal and spatial patterns of expression of inhibitors of apoptosis in human placentas

The apoptosis cascade that plays a central role in normal and pathological processes is strictly controlled, in part by newly described members of the inhibitor of apoptosis (IAP) family (HIAP-1, HIAP-2, XIAP, NAIP, Survivin, and Livin). Here, we report the expression of IAP mRNAs and proteins in early and late gestation human placentas, term cytotrophoblast cells, and two choriocarcinoma cell lines, JEG-3 and Jar. Reverse transcriptase-polymerase chain reaction identified mRNAs derived from all of the currently known IAP genes in all samples. Analysis by immunoblotting revealed that IAP proteins are present in early and late gestation human placentas and that levels of IAPs are not identical in normal and transformed trophoblast cells. Immunohistochemical experiments performed on paraformaldehyde-fixed tissue sections taken from early and late stages of pregnancy demonstrated that expression patterns differed according to cell lineage and stage of cell differentiation. The results of this study are consistent with the postulate that IAP proteins have critical roles in placental cell survival and suggest that specific apoptosis inhibitors may protect normal and transformed trophoblast cells from cell death.

Expression of proliferation and apoptotic markers in human placenta during pregnancy

Trophoblast has unique properties in relation to its wide range of metabolic, endocrine and angiogenic functions. Trophoblastic cells invade endometrium and adjacent myometrium in a way that is imitated by malignant tumours. The aim of the present study was to analyse the expression of markers of proliferation and apoptosis in trophoblastic cells in normal human placenta during pregnancy. A total of 22 placentas, 12 of which were obtained from curettage and induced legal abortion and 10 placentas obtained from normal deliveries or caesarean sections were included in this study. Proliferation markers were strongly expressed in cytotrophoblast in early stages of gestation. In late term placentas, a distinct decrease in expression of these markers was observed. Syncytiotrophoblast was negative for proliferation markers in all placentas. Positive immunostaining for bcl-2, an anti-apoptotic marker, was observed only in syncytiotrophoblastic cells in first-trimester but also in third-trimester placentas. Cytotrophoblast and stromal mesenchymal cells of chorionic villi were negative for bcl-2. Expression of bcl-2 protein in syncytiotrophoblast may be one of the major factors preventing these structures from early cell death, which is indispensable for the maintenance of physiological pregnancy.

Hyperglycemia-induced apoptosis affects sex ratio of bovine and murine preimplantation embryos

The effect of glucose in the medium used during in vitro culture on both cell death by apoptosis and the sex ratio of bovine blastocysts derived from in vitro-matured and in vitro-fertilized oocytes was evaluated. Oocytes were matured, inseminated, and cultured in vitro in mSOF medium with 10% FCS with or without glucose supplementation. Exposure to high concentrations of glucose (10, 20, and 30 mM) during bovine embryo development in vitro from zygote to blastocyst resulted in a decrease in the number of cells per embryo and an increase in the frequency of apoptotic cells. A significantly higher proportion of females was found among those embryos that developed under hyperglycemic conditions in vitro. Moreover, both murine and bovine blastocysts incubated for 6 hr in 20 mM glucose had a significantly higher number of apoptotic cells in comparison to control. In this study, we also determined whether blastocyst production of the X-linked inhibitor of apoptosis protein (XIAP) differs between the sexes. Our results show that female bovine blastocysts produce significantly higher amounts of XIAP mRNA than males and this could be crucial in explaining the higher proportion of female blastocysts observed following in vitro culture under hyperglycemic conditions which induce apoptosis. Moreover, a higher proportion of female murine blastocysts cultured under hyperglycemic conditions were implanted in the uterus (65.3 of implantations from embryos cultured with 20 mM of glucose are females vs. 49% in control). This mechanism provides an explanation for the significant reduction of male children born to diabetic mothers.

Apoptosis and related proteins in placenta of intrauterine fetal death in prostaglandin f receptor-deficient mice

The present study investigated whether the increase of apoptosis in the placenta is associated with intrauterine fetal death in prostaglandin F receptor-deficient mice. Apoptosis was demonstrated within placental and decidual tissue by the TUNEL method. The majority of apoptosis was found in syncytiotrophoblast tissues. Enhanced TUNEL-positive staining in the syncytiotrophoblast layer was scattered in the placental tissues in clusters of apoptotic cells in the death group. Marked TUNEL-positive cells were identified in decidua of both groups. The rate of apoptosis in the placenta and decidua in the death group was higher than that in the survival group (P < 0.05). Immunohistochemical analysis showed that the level of active caspase-3 protein expression in the placenta in the death group was much higher than that in the survival group. The level of Bcl-2 protein expression in the placenta in the death group was much lower than that in the survival group. Western blot analysis demonstrated that increased expression of the active form of caspase-3 was detected in the placenta and decidua in the death group compared with that in the survival group. In contrast, a decrease in the expression of Bcl-2 was detected in the placenta and decidua in the death group compared with that in the survival group. Enhanced expression of Bax:Bcl-2 ratio was detected in placenta and decidua in the death group compared with that in the survival group. Thus, significantly increased apoptosis in the mouse placenta and decidua might be involved in the pathophysiologic mechanism of intrauterine fetal death.

Influence of maternal smoking on trophoblast apoptosis throughout development: possible involvement of Xiap regulation

Maternal smoking is associated with severe perinatal complications and significant placental pathologies with underlying ultrastructural changes. In this study, we examined the influence of maternal smoking on trophoblast apoptosis throughout development and correlated those findings with changes in expression of X-linked inhibitor of apoptosis protein (Xiap) as well as Fas and Fas ligand (FasL). Trophoblast apoptosis was determined by DNA fragmentation and TUNEL. Protein expression was assessed by Western blotting and immunohistochemistry. Maternal smoking was associated with increased trophoblast apoptosis in the first trimester but decreased trophoblast apoptosis near term. Placental Xiap levels decreased significantly throughout development in nonsmokers (P < 0.05) but remained elevated in smokers. Fas and FasL levels did not vary significantly throughout development nor between groups. However, procaspase-3 levels were significantly increased in smokers at term. Our results suggest that maternal smoking has different effects at different stages of trophoblast differentiation and that this is regulated in part through modulations in placental Xiap expression.