The proneural genes NEUROD1 and NEUROD2 are expressed during human trophoblast invasion

Hypoxia Inducible Factors (HIF1α and HIF3α) are differentially methylated in preeclampsia placentae and are associated with birth outcomes

Preeclampsia is a placental vascular pathology and hypoxia is known to influence placental angiogenesis. Hypoxia Inducible Factors (HIF1α and HIF3α) mediate the response to cellular oxygen concentration and bind to hypoxia response element of target genes. However the mechanism regulating above activity is not well-understood. We investigated if placental DNA methylation (DNAm) and expression of HIF1α and 3α genes are altered and associated with pre-eclampsia, placental weight and birth outcomes. Using a cohort comprising women with preeclampsia [N = 100, delivering at term (N = 43) and preterm (N = 57)] and normotensive controls (N = 100), we analysed DNAm in HIF1α and 3α, and their mRNA expression in placentae, employing pyrosequencing and quantitative real-time PCR, respectively. We observed significant hypermethylation at cg22891070 of HIF3α in preeclampsia placentae compared to controls (β = 1.5%, p = 0.04). CpG8 in the promoter region of HIF1α, showed marginally significant hypomethylation in preterm preeclampsia compared to controls (β = - 0.15%, p = 0.055). HIF1α expression was significantly lower in preterm preeclampsia compared to controls (mean ± SE = 10.16 ± 2.00 vs 4.25 ± 0.90, p = 0.04). Further, DNAm in HIF1α promoter region was negatively associated with its expression levels (β =  - 0.165, p = 0.024). Several CpGs in HIF1α were negatively associated with placental weight and birth outcomes including birth weight (β range =  - 0.224-0.300) and birth length [β range =  - 0.248 to - 0.301 (p < 0.05 for all)]. Overall, we demonstrate altered DNAm in HIF1α and HIF3α in preeclampsia placentae, also associated with various birth outcomes. Correlation of DNAm in HIF1α and its expression suggests a possible role in the pathogenesis of pre-eclampsia. Further investigations on interactions between HIF1α and HIF3α in preeclampsia would be interesting.

Basic Helix-Loop-Helix Transcription Factor Profiling of Lung Tumors Shows Aberrant Expression of the Proneural Gene Atonal Homolog 1 (ATOH1, HATH1, MATH1) in Neuroendocrine Tumors

Microarray-based expression profiling studies of lung adenocarcinomas have defined neuroendocrine subclasses with poor prognosis. As neuroendocrine development is regulated by members of the achaetescute and atonal classes of basic helix-loop-helix (bHLH) transcription factors, we analyzed lung tumors for expression of these factors. Out of 13 bHLH genes tested, 4 genes, i.e., achaetescute complex-like 1 (ASCL1, HASH1, Mash1), atonal homolog 1 (ATOH1, HATH1, MATH1), NEUROD4 (ATH-3, Atoh3, MATH-3) and neurogenic differentiation factor 1 (NEUROD1, NEUROD, BE-TA2), showed differential expression among lung tumors and absent or low expression in normal lung. As expected, tumors that have high levels of ASCL1 also express neuroendocrine markers, and we found that this is accompanied by increased levels of NEUROD1. In addition, we found ATOH1 expression in 9 (16%) out of 56 analyzed adenocarcinomas and these tumors showed neuroendocrine features as shown by dopa decarboxylase mRNA expression and immunostaining for neuroendocrine markers. ATOH1 expression as well as NEUROD4 was observed in small cell lung carcinoma (SCLC), a known neuroendocrine tumor. Since ATOH1 is not known to be involved in normal lung development, our results suggest that aberrant activation of ATOH1 leads to a neuroendocrine phenotype similar to what is observed for ASCL1 activation during normal neuroendocrine development and in lung malignancies. Our preliminary data indicate that patients with ATOH1-expressing adenocarcinomas might have a worse prognosis.

The significance of Trk receptors in pancreatic cancer

This study investigated the Trk receptor family as a therapeutic target in pancreatic ductal adenocarcinoma and assessed their prognostic significance. Global gene expression analysis was investigated in prospectively collected pancreatic ductal adenocarcinomas that had either undergone neoadjuvant chemoradiation or were treated by surgery. PANC-1 and MIA-PaCa-2 cell lines were investigated to establish whether fractionated radiation altered expression of four neuroendocrine genes and whether this resulted in subsequent changes in radiosensitivity. A specific inhibitor of TrkA, B, and C, AstraZeneca 1332, was investigated in vitro and in vivo in combination with radiation. A tissue microarray was constructed from 77 pancreatic ductal adenocarcinoma patients who had undergone neoadjuvant chemoradiation and the Trk receptor, and neurogenic differentiation 1 expression was assessed and correlated with overall survival. A total of 99 genes were identified that were differentially expressed in the chemoradiation patients with neuroendocrine genes and pathways, in particular the neurogenic differentiation 1 and Trk receptor family, being prominent. Fractionated radiation upregulated the expression of neuroendocrine genes, and AstraZeneca 1332 treatment in vitro enhanced radiosensitivity. No added effect of AstraZeneca 1332 was observed in vivo. Trk receptor expression varied between isoforms but did not correlate significantly with clinical outcome. Radiation treatment upregulated neuroendocrine gene expression but the Trk receptor family does not appear to be a promising treatment target.

Effect of NeuroD gene silencing on the migration and invasion of human pancreatic cancer cells PANC-1

The aim of this study is to investigate the influence of Lenti-EGFP-NeuroD-miR, RNAi lentiviral expression vector, on the expression level of NeuroD and migration, and invasion of PANC-1 cell line. PANC-1 cells were cultured and cotransfected with Lenti-EGFP-NeuroD-miR and Lenti-GFP. The infection rate of lentivirus was determined by fluorescence. The interfering effection by the expression of NeuroD mRNA in PANC-1 cells was analyzed by real-time PCR after transfected. Biological behavior of PANC-1 cells transinfected was observed, and the migration and invasion were studied by transwell assay. Intrapancreatic allografts model in nude mice was established to observe the effects of NeuroD on tumorigenesis, tumor growth, and invasion in vivo. The expression of NeuroD mRNA decreased significantly after RNAi lentivirus transinfecting PANC-1 cell. The cell's migration and invasion ability decreased obviously as soon as down regulate of NeuroD in PANC-1 cells. Comparing with control group, the tumors were smaller in size and the invasiveness was inhibited after 8 weeks intrapancreatic allografts in nude mice. Lenti-EGFP-NeuroD-miR transfected into PANC-1 cells shows a stable, effective, and especial blocking expression of NeuroD in mRNA level. The RNAi of lentiviral vector target NeuroD can reduce the migration and invasion abilities of PANC-1 cells.

Microarray analysis of the hypoxia-induced gene expression profile in malignant C6 glioma cells

Hypoxia is commonly featured during glioma growth and plays an important role in the processes underlying tumor progression to increasing malignancy. Here we compared the gene expression profiles of rat C6 malignant glioma cells under normoxic and hypoxic conditions by cDNA microarray analysis. Compared to normoxic culture conditions, 180 genes were up-regulated and 67 genes were down-regulated under hypoxia mimicked by CoCl2 treatment. These differentially expressed genes were involved in mutiple biological functions including development and differentiation, immune and stress response, metabolic process, and cellular physiological response. It was found that hypoxia significantly regulated genes involved in regulation of glycolysis and cell differentiation, as well as intracellular signalling pathways related to Notch and focal adhesion, which are closely associated with tumor malignant growth. These results should facilitate investigation of the role of hypoxia in the glioma development and exploration of therapeutic targets for inhibition of glioma growth.

Homeodomain protein HLX is expressed primarily in cytotrophoblast cell types in the early pregnancy human placenta

Homeobox genes are a large family of transcription factors. Of these, the HLX homeobox gene (previously known as HLX1 and HB24) is important for normal placentation. We have previously shown that HLX mRNA expression is significantly reduced in fetal growth-restricted human placentae compared with control placentae. In this study, a rabbit polyclonal antibody to the homeodomain protein HLX was raised and characterised. Western analysis revealed a protein of 50 kDa. HLX protein was detected in cellular nuclei in the cytotrophoblast-derived cell lines HTR8/SVneo, SGHPL-4, JEG-3, JAR and BeWo. Dual labelling with cytokeratin 7 was used to determine the spatial distribution of HLX in the early placenta and fetal membranes, showing both a perinuclear and punctate nuclear distribution for HLX. In the early pregnancy placenta HLX was localised to villous cytotrophoblast, and extravillous cytotrophoblast nuclei in the proximal regions of the cytotrophoblast cell columns, but was not detected at significant levels in the syncytiotrophoblast. In first trimester placental bed biopsies, HLX expression was not localised to the nucleus but instead was found in the cytoplasm. We conclude that HLX is primarily expressed in cytotrophoblast cell types in the human placenta and propose that HLX is involved in cytotrophoblast proliferation and downregulation of cell differentiation.

The human fetal cochlea can be a source for auditory progenitors/stem cells isolation

The development of new stem cell-based technologies is creating new hopes in regenerative medicine. Hearing-impaired individuals should benefit greatly from the development of a cell-based regenerative strategy to treat deafness. An important achievement would be to develop a human-based system that could bring the advances made in animal models closer to clinical application. In this work, we have explored the suitability of the developing fetal cochlea to be used as a source for the extraction of auditory progenitor/stem cells. We have established cultures that express critical markers such as NESTIN, SOX2, GATA3 and PAX2. These cultures can be expanded in vitro for several months and differentiating markers such as ATOH1/HATH1 and POU4F3/BRN3C can be induced by manipulating the culture conditions using specific growth factors such as bFGF, EGF and retinoic acid.

Antibodies to Trophoblast Antigens HLA-G, Placenta Growth Factor, and NeuroD2 Do Not Improve Detection of Circulating Trophoblast Cells in Maternal Blood

OBJECTIVES

Non-invasive prenatal diagnosis using circulating fetal trophoblast cells has been challenging due to lack of a reproducible trophoblast-specific antibody. We investigated the use of three trophoblast cell-specific antibodies, HLA-G, placenta growth factor, and neuroD2, for the isolation of trophoblast cells from the maternal circulation.

METHODS

Trophoblast cells were isolated by density centrifugation from maternal blood samples (gestational age 10-20 weeks, n = 9). All women were carrying a male fetus. Following immunocytochemical staining with the trophoblast-specific antibodies, fluorescent in situ hybridization was performed, to verify whether any stained cells were indeed fetal.

RESULTS

The HLA-G antibody had a ubiquitous staining pattern, which was not specific for trophoblast cells. Neither the placenta growth factor nor the neuroD2 antibodies were able to identify any trophoblast cells. Following fluorescent in situ hybridization, no male cells were detected on any of the slides.

CONCLUSION

The antibodies used in this study were unable to improve detection of trophoblast cells in the maternal circulation.

Transcriptional profile of NeuroD expression in a human fetal astroglial cell line

NeuroD1, a member of the basic helix-loop-helix (bHLH) protein family, is a transcription factor that plays a pivotal role in terminal differentiation of neural progenitors. The primary objective was to generate an early transcriptional profile triggered by NeuroD1 to guide future studies on mechanisms of neuronal differentiation. The human NeuroD1 coding region was amplified from human fetal brain RNA using specific primers and cloned into a CMV expression vector (CT-GFP-TOPO/pcDNA3.1). Transfection of a fetal glial cell line with this construct resulted in expression of NeuroD1 in 13-15% of the cells. Markers typical of early neuronal development were observed by immunocytochemical staining in a small proportion of transfected cells. To enrich the population of NeuroD1-expressing cells, fluorescence-activated cell sorting (FACS) was used to purify and collect the NeuroD1/GFP+ cells. Total RNA was extracted from the pair of cultures (NeuroD1/GFP vs. control plasmid/GFP) and processed for gene expression studies. A final gene list was composed from those probe sets that were either increased or decreased in the NeuroD1-expressing cells in three independent experiments (p < 0.001). Each gene was investigated further for possible roles in neurogenesis and a subset of 177 genes was chosen based on the following characteristics: a) genes that are potential NeuroD1 dimerization partners, b) genes that modulate other bHLH transcription factors, c) genes related to development, and d) genes associated with neural induction, outgrowth, and terminal differentiation. DNA microarray analysis of NeuroD1 expression in an astroglial cell line produced a "snapshot" transcriptional profile that will be useful in deciphering the complex molecular code that specifies a neuronal fate.

Differential downregulation of αT-catenin expression in placenta: trophoblast cell type-dependent imprinting of the CTNNA3 gene

The alphaE-catenin is a well-known invasion suppressor. A recently described novel alpha-catenin, i.e. alphaT-catenin (CTNNA3), shows related functions being necessary for the formation of cell-cell adhesion complexes. We recently demonstrated that the 10q21.3 region containing the CTNNA3 gene shows a parent-of-origin effect and that transcription of the CTNNA3 gene is downregulated in placental tissues of complete androgenetic origin. As this suggests that the CTNNA3 gene is subject to imprinting, we performed allele-specific RT-PCR on early placenta tissues using informative heterozygous samples. This was supplemented by immunostaining for alphaT-catenin, p57KIP2 and low molecular weight cytokeratin in tissues of a partial hydatidiform mole. As shown here we demonstrate that the CTNNA3 gene is subject to imprinting with preferential expression of the maternal allele in first trimester placental tissues. Imprinting, however, is trophoblast cell type-dependent: expression in extravillus trophoblast is biallelic; expression in villus cytotrophoblast is from the maternal allele only. Expression of alphaT-catenin is lost in villus syncytiotrophoblast as well as in extravillus trophoblast following epithelial-mesenchymal transition. The trophoblast cell type-dependent imprinting of CTNNA3 is identical to p57KIP2 imprinting with respect to trophoblast cell type (villus) and parental origin of the expressed allele (maternal). This suggests that gene dosage compensation of CTNNA3 and p57KIP2 in the placenta shares a conserved regulatory mechanism that correlates with an early step in trophoblast determination, i.e. differentiation into villus or extravillus trophoblast.

NEUROD1 acts in vitro as an upstream regulator of NEUROD2 in trophoblast cells

The basic helix-loop-helix (bHLH) transcription factors NEUROD1, NEUROD2 and ATH2 are expressed during first trimester human placental development. We determined the transactivation potential of each of these factors in trophoblasts by measuring changes in the endogenous gene activity using absolute quantification by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) after transient transfection. In these assays, NEUROD1 was found to transiently transactivate NEUROD2 in trophoblast cells. Promotor truncation assays, using luciferase constructs, showed the presence of two domains in the NEUROD2 promotor, which showed increased activity after NeuroD1 transfection. Each of these NeuroD1-responsive domains contains an E-box sequence. The NEUROD2 transactivation data fit with the spatial expression pattern of NEUROD1 and NEUROD2, since they are expressed in endovascular trophoblasts. This expression pattern, as well as the present transactivation results, might suggest the presence of a NEUROD differentiation cascade during first trimester human placental development.

The cellular Pax–Hox–Helix connection

Basic helix-loop-helix (bHLH) transcription factors are important regulators of lineage determination during embryogenesis. Initial experiments in Drosophila showed that early neural selection and specification are dependent on atonal (ato) and members of the achaete-scute complex (as-c). In mammals, transcription factors homologous to as-c and ato are causally involved during development of organs throughout the body. Development of subsets of lineages in intestine, stomach, pancreas, lung, thyroid and placenta have been shown to be regulated by members of the as-c and ato families. These functional studies show that an individual bHLH transcription factor can regulate multiple developmental processes throughout the mammalian body, which implicates that extant as-c and ato transcription factors play a distinct function dependent on their cellular context. Based on the synergistic activation of the insulin, POMC and Pax4 promotors by bHLH and homeobox (Hox) protein complexes, we hypothesize that the underlying cellular function-modulating factors include members of the Hox and paired box (Pax) multigene families. These examples indicate that unique combinations of bHLH and Hox proteins, mediated by protein-protein interactions, might be responsible for activating cell-specific sets of target genes.

Regulatory transcription factors controlling function and differentiation of human trophoblast--a review

In transgenic mice, homozygous mutations of trophoblast-specific transcription factors such as Hand1, Mash-2, I-mfa or GCM1 revealed their key regulatory roles in induction, maintenance or differentiation of distinct placental trophoblast subpopulations in vivo. Descriptive studies have shown that several of these factors are also expressed in the human placenta, suggesting that the molecular mechanisms governing trophoblast differentiation could be similar in mice and men. While an increasing number of putative developmental regulators are being identified in the human placenta, little information is available regarding whether the particular factors play an essential role in trophoblast differentiation processes such as formation of anchoring villi, placental bed invasion or syncytialization. However, expression of abundant trophoblast-specific products such as hormones can be regarded as a hallmark of differentiation, suggesting that the factors controlling their transcription could also be involved in the developmental processes of the placenta. Indeed, studies in different model systems revealed that the human homologues of murine trophoblast-specific transcriptional regulators interact with the promoter regions of typical placental genes such as aromatase P450 (CYP19), chorionic gonadotrophin (CG) or placental lactogen (PL). Additionally, the unique combination of more broadly distributed transcription factors of the Sp or Ap-2 protein family in a particular trophoblast cell type is required to govern mRNA expression in a differentiation-dependent manner. Here, we will summarize our present knowledge on these individual transcription factors that are involved in human trophoblast function and differentiation.

Circulating trophoblast in maternal blood

This review describes the status of circulating trophoblast, but is considered in the perspective that only a specific subset of trophoblast cells circulates in the maternal blood. The consequences for isolation, identification and clinical potential are described.