Expression of HOX gene products in normal and abnormal trophoblastic tissue

Homeobox genes in the human placenta: Twists and turns on the path to find novel targets

Fetal growth restriction (FGR) is a clinically important human pregnancy disorder that is thought to originate early in pregnancy and while its aetiology is not well understood, the disorder is associated with placental insufficiency. Currently treatment for FGR is limited by increased surveillance using ultrasound monitoring and premature delivery, or corticosteroid medication in the third trimester to prolong pregnancy. There is a pressing need for novel strategies to detect and treat FGR at its early stage. Homeobox genes are well established as master regulators of early embryonic development and increasing evidence suggests they are also important in regulating early placental development. Most important is that specific homeobox genes are abnormally expressed in human FGR. This review focusses on identifying the molecular pathways controlled by homeobox genes in the normal and FGR-affected placenta. This information will begin to address the knowledge gap in the molecular aetiology of FGR and lay the foundation for identifying potential diagnostic and therapeutic targets.

Investigation of HoxB3 and Growth Factors Expression in Placentas of Various Gestational Ages

An evaluation of transforming growth factor beta (TGFβ), hepatocyte growth factor (HGF), basic fibroblast growth factor (FGF-2), fibroblast growth factors receptor 1 (FGFR1) and Hox-positive cells in the human placenta, and their correlation with gestational time at delivery and pregnancy outcomes, may provide not only a better understanding of the role of Hox genes and growth factors in human development, but also may be of clinical importance in reproductive medicine. This study analyzed the immunohistochemical identification of TGFβ, HGF, FGF-2, FGFR1 and HoxB3 in placentas of various gestational ages. We found few (+) TGFβ, moderate (++) FGF-2 and numerous (+++) HGF and FGFR1 positive structures. Occasional (0/+) to numerous (+++) HoxB3-positive structures were detected in different types of placental cells specifically, cytotrophoblasts, syncytiotrophoblast, extravillous trophoblasts, and Höfbauer cells. Correlating the appearance of HoxB3 staining in placentas with neonatal parameters, we found a statistically significant negative correlation with ponderal index (r = −0.323, p = 0.018) and positive correlation with neonate body length (r = 0.541, p = 0.046). The number of HoxB3-positive cells did not correlate with growth factors and gestational age, but with neonatal anthropometrical parameters, indicating the role of HoxB3 not only in placental development, but also in the longitudinal growth of the fetus. TGFβ and FGF-2 did not play a significant role in the development of the placenta beyond 22nd week of pregnancy, while HGF and FGFR1 immunoreactive cells increased with advancing gestation, indicating increasingly evolving maturation (growth, proliferation) of the placenta, especially in the third trimester.

The distribution of some homeobox proteins in the bovine placenta during gestation

Homeobox proteins are transcription factors known to be involved in the molecular basics of body model formation and transformation. Some homeobox proteins are known to play critical roles in the control of the extraembryonic development of the placenta during gestation and in the regulation of uterine and placental physiology in adults. The gravid uteruses and placentas of 27 Holsteins cows, obtained from private slaughterhouses, were used in this study. The tissues were assigned to three groups as belonging to the first, second and third timesters of gestation, based on the fetal ages determined. Subsequently, the tissues were subjected to immunohistochemical staining using antibodies specific to the proteins investigated in the study. The evaluation of the immunohistochemical findings obtained in this study, demonstrated the presence of trimester-dependent varying intensities of immunoreactions in the uterus and placenta. Immunoreactivity was observed particularly in the luminal and glandular epithelial cells of the uterus, as well as in stromal and some endothelial cells. Furthermore, immunoreactivity for the proteins HOXA10, HOXB6, HOXC6 and Dlx-5 was determined in the smooth muscle cells. Moreover, immunoreactivity was also detected in the maternal epithelium and fetal trophoblasts found in the structure of the placenta. The results suggest that the homeobox proteins investigated may have critical roles in the regulation of endometrial functions in cows, and the proliferation and differentiation of endometrial and placental cells. It is concluded that these proteins may have physiological roles in the formation and development of the placenta, as well as in the maintenance of pregnancy.

MicroRNA-652-3p promotes the proliferation and invasion of the trophoblast HTR-8/SVneo cell line by targeting homeobox A9 to modulate the expression of ephrin receptor B4

MicroRNAs (miRNAs) are emerging as novel modulators in the pathogenesis of preeclampsia (PE). Multiple miRNAs have been shown to regulate the proliferation and invasion of trophoblast cells, which play a critical role in successful pregnancies. miR-652-3p has been identified as a novel disease-associated miRNA that is dysregulated in various pathological processes. However, whether miR-652-3p is dysregulated in PE and regulates the cellular function of trophoblast cells remains unknown. In the present study, we aimed to investigate the expression pattern of miR-652-3p in PE and explore its potential function in trophoblast cells. Herein, we found that miR-652-3p expression was significantly decreased in the placental tissues of pregnant women with PE. Cellular function experiments showed that overexpression of miR-652-3p promoted the viability, proliferation, and invasion of trophoblast cells in vitro. By contrast, inhibition of miR-652-3p had the opposite effect. Bioinformatics analysis predicted that homeobox A9 (HOXA9), a crucial regulator of trophoblast cell function, was a potential target gene of miR-652-3p. A luciferase reporter assay confirmed that miR-652-3p directly interacted with the 3'-untranslated region of HOXA9. Moreover, miR-652-3p was shown to negatively regulate the expression of HOXA9 and ephrin receptor B4 (EphB4) in trophoblast cells. Notably, overexpression of HOXA9 or EphB4 significantly reversed the regulatory effect of miR-652-3p on proliferation and invasion of trophoblast cells. Taken together, our findings demonstrate that miR-652-3p regulates the proliferation and invasion of trophoblast cells, possibly through targeting HOXA9 and modulating EphB4 expression.

HOXA9 transcriptionally regulates the EPHB4 receptor to modulate trophoblast migration and invasion

INTRODUCTION

Functional placenta formation is crucially dependent on extravillous trophoblast migration and invasion. EPHB4 has been identified to play a negative but important role in regulating trophoblast biological function, whereas the upstream regulation mechanism remains unknown. As reported, there is a transcriptional stimulation of EPHB4 expression consequent to HOXA9 activation in endothelial cells (ECs). Therefore, this study is conducted to investigate the role of HOXA9 and its relationship with EPHB4 in trophoblast cells.

METHOD

Both mRNA and protein expression levels of HOXA9 and EPHB4 were measured in preeclamptic placenta (n = 15) and normal placenta (n = 15). Next, the expression and location of HOXA9 and EPHB4 in first-trimester villi were shown via immunohistochemistry. Trophoblast cell line HTR-8/SVneo was used to explore the effect of HOXA9 on EPHB4 expression and trophoblast bioactivity by gain- and loss-of function studies. In addition, chromatin immunoprecipitation (ChIP) and luciferase assays were conducted to clarify the regulation mechanism of HOXA9 on EPHB4 expression in HTR-8/SVneo.

RESULT

HOXA9 and EPHB4 expression were increased in preeclamptic placenta compared with normal placenta. HOXA9 could promote EPHB4 expression and impaired HTR-8/SVneo cells migration and invasion. ChIP and luciferase assays revealed that HOXA9 could directly bind to EPHB4 promoter and promoted its transcription.

CONCLUSION

HOXA9 transcriptionally regulated EPHB4 expression to modulate trophoblasts migration and invasion, which may suggest a contribution of HOXA9-EPHB4 in the poor placentation in the pathogenesis of preeclampsia.

Dynamic Pattern of HOXB9 Protein Localization during Oocyte Maturation and Early Embryonic Development in Mammals

Background

We previously showed that the homeodomain transcription factor HOXB9 is expressed in mammalian oocytes and early embryos. However, a systematic and exhaustive study of the localization of the HOXB9 protein, and HOX proteins in general, during mammalian early embryonic development has so far never been performed.

Results

The distribution of HOXB9 proteins in oocytes and the early embryo was characterized by immunofluorescence from the immature oocyte stage to the peri-gastrulation period in both the mouse and the bovine. HOXB9 was detected at all studied stages with a dynamic expression pattern. Its distribution was well conserved between the two species until the blastocyst stage and was mainly nuclear. From that stage on, trophoblastic cells always showed a strong nuclear staining, while the inner cell mass and the derived cell lines showed important dynamic variations both in staining intensity and in intra-cellular localization. Indeed, HOXB9 appeared to be progressively downregulated in epiblast cells and only reappeared after gastrulation had well progressed. The protein was also detected in the primitive endoderm and its derivatives with a distinctive presence in apical vacuoles of mouse visceral endoderm cells.

Conclusions

Together, these results could suggest the existence of unsuspected functions for HOXB9 during early embryonic development in mammals.

SALL4 expression in gestational trophoblastic tumors: a useful tool to distinguish choriocarcinoma from placental site trophoblastic tumor and epithelioid trophoblastic tumor

SALL4 has important functions in embryonic stem cells. The aim of this study was to investigate SALL4 expression in gestational trophoblastic neoplasia. We hypothesized that it could help to distinguish choriocarcinoma, the presumed most primitive form of gestational trophoblastic neoplasia, from placental site trophoblastic tumor and epithelioid trophoblastic tumor, which would be more differentiated variants. This study included 31 gestational trophoblastic neoplasias: 19 choriocarcinomas, 9 placental site trophoblastic tumors, 1 epithelioid trophoblastic tumor, and 2 mixed tumors comprising a placental site trophoblastic tumor and an epithelioid trophoblastic tumor. Unlike usual markers of gestational trophoblastic neoplasia (p63, human chorionic gonadotrophin and human placental lactogen), SALL4 was expressed in 100% of choriocarcinomas and it was not detected in any placental site trophoblastic tumor and epithelioid trophoblastic tumor. However, the proportion of positive cells varied in a wide range, from 10% to 70%, reflecting the fact that SALL4 was specifically present in mononuclear cells consistent with neoplastic cytotrophoblast. So, SALL4 may be helpful in the differential diagnosis of gestational trophoblastic neoplasias.

An EG-VEGF-Dependent Decrease in Homeobox Gene NKX3.1 Contributes to Cytotrophoblast Dysfunction: A Possible Mechanism in Human Fetal Growth Restriction

Idiopathic fetal growth restriction (FGR) is frequently associated with placental insufficiency. Previous reports have provided evidence that endocrine gland-derived vascular endothelial growth factor (EG-VEGF), a placental secreted protein, is expressed during the first trimester of pregnancy, controls both trophoblast proliferation and invasion, and its increased expression is associated with human FGR. In this study, we hypothesize that EG-VEGF-dependent changes in placental homeobox gene expressions contribute to trophoblast dysfunction in idiopathic FGR. The changes in EG-VEGF-dependent homeobox gene expressions were determined using a homeobox gene cDNA array on placental explants of 8-12 wks gestation after stimulation with EG-VEGF in vitro for 24 h. The homeobox gene array identified a greater-than-five-fold increase in HOXA9, HOXC8, HOXC10, HOXD1, HOXD8, HOXD9 and HOXD11, while NKX 3.1 showed a greater-than-two-fold decrease in mRNA expression compared with untreated controls. Homeobox gene NKX3.1 was selected as a candidate because it is a downstream target of EG-VEGF and its expression and functional roles are largely unknown in control and idiopathic FGR-affected placentae. Real-time PCR and immunoblotting showed a significant decrease in NKX3.1 mRNA and protein levels, respectively, in placentae from FGR compared with control pregnancies. Gene inactivation in vitro using short-interference RNA specific for NKX3.1 demonstrated an increase in BeWo cell differentiation and a decrease in HTR-8/SVneo proliferation. We conclude that the decreased expression of homeobox gene NKX3.1 downstream of EG-VEGF may contribute to the trophoblast dysfunction associated with idiopathic FGR pregnancies.

Blood pressure modulation following activation of mast cells by cationic cell penetrating peptides

Short cell penetrating peptides (CPP) are widely used in vitro to transduce agents into cells. But their systemic effect has not been yet studied in detail. We studied the systemic effect of the cell penetrating peptides, penetratin, transportan and pro-rich, on rat hemodynamic functions. Intra-arterial monitoring of blood pressure showed that injection of the positively charged penetratin and transportan in a wide range of concentrations (2.5-320 μg/kg) caused highly significant transient decrease in the systolic and diastolic blood pressure in a dose dependent manner (p<0.01). Pretreatment with histamine receptors blockers or with cromolyn, a mast cell stabilizing agent, significantly attenuated this effect. Furthermore, in vitro incubation of these both peptides with mast cells line, LAD2, caused a massive mast cell degranulation. In vitro studies showed that these CPP in a wide range of concentrations were not cytotoxic without any effect on the survival of LAD2 mast cell line. In contrast, the less positively charged and proline-rich CPP, pro-rich, had no systemic effects with no effect on mast cell degranulation. Our results indicate that intravenously administrated positively charged CPP may have deleterious consequences due to their induced BP drop, mediated by mast cell activation. Therefore, the major effect of mast cell activation on BP should be considered in developing possible future drug therapies based on the injection of membrane-permeable and positively charged CPP. Nevertheless, lower levels of such CPP may be considered as a treatment of systemic high BP through moderate systemic mast cell activation.

Peritoneal inclusion cysts in adolescent females: a clinicopathological characterization of four cases

STUDY OBJECTIVE

To identify adolescent females with peritoneal inclusion cysts and characterize the clinicopathologic features.

DESIGN

Observational and chart review along with immunohistochemical studies.

SETTING

University pediatric and adolescent clinic.

RESULTS

Medical records of all subjects, ages 10-18 years, diagnosed with peritoneal inclusion cysts over a 4-year period were retrospectively reviewed. Four patients, ages 11-16 years (mean, 13.8 yrs) were identified. Pelvic pain was the most common presenting symptom. No palpable abdominal or pelvic masses were detected. However, pelvic lesions were identified by radiographic studies in three of the four patients. Half experienced tenderness on examination. With one exception, all had a prior history of abdominal surgery. Twelve peritoneal inclusion cysts were identified, ranging from 1 cm to 7 cm in greatest diameter. Most were uninvolved in coexisting adhesions and non-adherent to pelvic or abdominal structures. Each had a well-defined pedicle connection to the peritoneum. No associated complications were identified. Their appearance conformed to established morphologic and immunohistochemical criteria, although accompanying mesothelial-associated changes occasionally reported in other populations were not detected. No recurrences were recorded.

CONCLUSION

Young female adolescents with peritoneal inclusion cysts share presenting symptoms and histories of previous abdominal surgery similar to those reported in older female adolescents and adults. A palpable mass may not be detected on examination, but can often be identified using radiographic studies. Our cases differ from previous reports by smaller cyst size, presence of a pedicle, and uncomplicated gross and microscopic appearances. Additionally, local recurrences and associated complications occurred less than reported in adults.

Ultraconserved coding regions outside the homeobox of mammalian Hox genes

Background

All bilaterian animals share a general genetic framework that controls the formation of their body structures, although their forms are highly diversified. The Hox genes that encode transcription factors play a central role in this framework. All Hox proteins contain a highly conserved homeodomain encoded by the homeobox motif, but the other regions are generally assumed to be less conserved. In this study, we used comparative genomic methods to infer possible functional elements in the coding regions of mammalian Hox genes.

Results

We identified a set of ultraconserved coding regions (UCRs) outside the homeobox of mammalian Hox genes. Here a UCR is defined as a region of at least 120 nucleotides without synonymous and nonsynonymous nucleotide substitutions among different orders of mammals. Further analysis has indicated that these UCRs occur only in placental mammals and they evolved apparently after the split of placental mammals from marsupials. Analysis of human SNP data suggests that these UCRs are maintained by strong purifying selection.

Conclusion

Although mammalian genomes are known to contain ultraconserved non-coding elements (UNEs), this paper seems to be the first to report the UCRs in protein coding genes. The extremely high degree of sequence conservation in non-homeobox regions suggests that they might have important roles for the functions of Hox genes. We speculate that UCRs have some gene regulatory functions possibly in relation to the development of the intra-uterus child-bearing system.

Des andro- et parthénogénotes humains (môles hydatiformes et tératomes ovariens) au cancer

Genomic imprinting is a process that appeared in mammals. This phenomenon blocks the normal development of parthenogenic and androgenic conceptuses, that is to say benign ovarian teratomas and hydatidiform moles respectively. Pathological modifications of these conceptuses depend on whether the chromosomes come from the mother or father. These pathologies are associated with an accidental anomaly during gametogenesis and/or fertilizing. These reproductive anomalies are sporadic and some familial cases may exist suggesting a genetic control of such diseases. The human andro- and parthenogenetic conceptuses, but more frequently the moles, may be invasive (choriocarcinoma). An imbalance of the imprinting genes may initiate the deregulation of other genes, including oncogenes and anti-oncogenes, which can explain the cancerous modification. Immunological and environmental factors must be also considered (presence of the only paternal chromosomes in the choriocarcinoma). Numerous works on this subject are published and some recent important discoveries underline the roles of genes HOX, Tim P3, E-cad and p-16, and the recurrent chromosome anomalies 7q21+and 8p21- in the mole to choriocarcinoma processing. Although these phenomena are complex and heterogeneous, the andro- and parthenogenote conceptuses are particularly interesting models with which to understand developmental disorders and cancerous progression.