Differential display RT-PCR analysis of human choriocarcinoma cell lines and normal term trophoblast cells: identification of new genes expressed in placenta

Myostatin: a multifunctional role in human female reproduction and fertility - a short review

Myostatin (MSTN) is member of the transforming growth factor β (TGF-β) superfamily and was originally identified in the musculoskeletal system as a negative regulator of skeletal muscle growth. The functional roles of MSTN outside of the musculoskeletal system have aroused researchers' interest in recent years, with an increasing number of studies being conducted in this area. Notably, the expression of MSTN and its potential activities in various reproductive organs, including the ovary, placenta, and uterus, have recently been examined. Numerous studies published in the last few years demonstrate that MSTN plays a critical role in human reproduction and fertility, including the regulation of follicular development, ovarian steroidogenesis, granule-cell proliferation, and oocyte maturation regulation. Furthermore, findings from clinical samples suggest that MSTN may play a key role in the pathogenesis of several reproductive disorders such as uterine myoma, preeclampsia (PE), ovary hyperstimulation syndrome (OHSS), and polycystic ovarian syndrome (PCOS). There is no comprehensive review regarding to MSTN related to the female reproductive system in the literature. This review serves as a summary of the genes in reproductive medicine and their potential influence. We summarized MSTN expression in different compartments of the female reproductive system. Subsequently, we discuss the role of MSTN in both physiological and several pathological conditions related to the female fertility and reproduction-related diseases.

The expression and potential functions of placental myostatin

Myostatin (growth differentiation factor-8; GDF-8) is a potent negative regulator of muscle development affecting both proliferation and differentiation. Myostatin has been reported to enhance the release of cytokines, including TNF-α (a pro-inflammatory cytokine involved in implantation). In the human placenta, myostatin production is negatively correlated with gestational age and has been implicated in the control of glucose uptake. Preliminary data indicate its expression is primarily localized to cytotrophoblast and syncytiotrophoblast. The role of myostatin in the placenta, however, remains to be fully elucidated. We speculate that myostatin is key regulator that contributes to placentation and the regulation of placental function throughout pregnancy.

Evaluation of deletions in 7q11.2 and 8p12–p21 as prognostic indicators of tumour development following molar pregnancy

OBJECTIVES

Previous studies have identified loss of chromosomal regions 7p12-q11.2 and 8p12-p21 in choriocarcinoma suggesting that suppressor genes involved in tumour development may be located within these regions. Our objectives were to refine the regions of loss and evaluate these deletions as prognostic indicators of trophoblastic tumour development following molar pregnancy.

METHODS

Fluorescent microsatellite genotyping was used to perform deletion mapping in a series of thirty-nine gestational trophoblastic tumours (GTT) including both choriocarcinoma and placental site trophoblastic tumours.

RESULTS

Significant loss of heterozygosity (LOH) was found for both regions in GTT that originated in non-molar pregnancies. Although no common interval of loss was found in those GTT with LOH for the 7q11.2 region, for the 8p12-p21 locus, markers D8S1731 and NEFL defined a minimal region of loss in all tumours showing LOH. However, complete LOH of either region occurred in only a minority of tumours (20%; chromosome 7: 24%; chromosome 8) suggesting that loss of neither region is likely to be a primary event in the development of GTT. This was further supported by the observation that no deletions were found in either region for the fourteen GTT that followed complete molar pregnancies.

CONCLUSIONS

While we have defined a minimal interval in 8p12-p21 in which tumour suppressor genes involved in GTT are likely to be located, the data suggest that deletions in 7q11.2 or 8p12-p21 are unlikely to be useful prognostic indicators in the management of patients with molar pregnancies.

Identification of differences in gene expression in primary cell cultures of human endometrial epithelial cells and trophoblast cells following their interaction

BACKGROUND

The interaction between epithelial cells of endometrium and trophoblast cells during implantation is presumed to be accompanied by a change in gene expression in the cell types involved. The objective of this study was to identify such differentially expressed genes.

METHODS

The interaction between the cell types was simulated in vitro by growing primary cell cultures of human endometrial epithelial cells and trophoblast cells together (co-culture) and separately (control cultures). Gene expression in the cell cultures was compared using the Differential Display method and confirmed using a modified Northern Blot method.

RESULTS

Twelve transcripts were identified as being differentially expressed following the interaction between trophoblast and endometrial cells. Some of these sequences show homology to known human genes while other sequences are coding for potential novel genes: (1) one sequence was homologous to the to Homer 1 gene, (2) one identical to the mRNA for XP-G factor, (3) one similar to a hypothetical protein, (4) transcripts showing homologies to a mRNA coding for a cellular proapoptotic protein, and (5) sequences homologous to regions on human chromosomes 5 and 16. Besides, some differentially expressed transcripts have sequences, which could be translated into ribosomal proteins or possibly code for novel proteins.

CONCLUSION

These sequences may be important to the course of events following the interaction between endometrial epithelial and trophoblast cells and responsible for implantation.

The Transcription Factor PLA-1/SKN-1A is Expressed in Human Placenta and Regulates the Placental Lactogen-3 Gene Expression

Here we report the selective expression of two POU transcription factor genes, PLA-1 and OCT-1, in human placenta and choriocarcinoma cell lines JAR, JEG-3 and BeWo. Pla-1 protein binds to a POU-consensus DNA sequence in the human placental lactogen-3 (PL-3) promoter and it is capable of trans-activating its transcription up to 18-fold. Other tissue-specific or ubiquitous POU transcription factors such as Pit-1/GHF-1 or Oct-1 showed none or low levels of trans-activation of the PL-3 promoter. In addition, we identified an unique and highly charged region in the N-terminal portion of Pla-1 protein required for full trans-activation of the PL-3 promoter.

Differential effects of inducers of syncytialization and apoptosis on BeWo and JEG-3 choriocarcinoma cells

BACKGROUND

The interactions of trophoblasts with the cytokine network at the fetomaternal interface determine the pathway the cell undertakes, e.g. proliferation, differentiation and apoptosis.

METHODS

We used cultures of fusigenic BeWo and non-fusigenic JEG-3 choriocarcinoma cells to study the effects of inducers of syncytialisation (forskolin) and apoptosis [tumour necrosis factor-alpha (TNFalpha)] on differentiation, viability, proliferation and apoptosis.

RESULTS

E-cadherin immunostaining showed that syncytium formation was confined to BeWo and not JEG-3 cells, while secretion of hCG was promoted by forskolin in both cell types implying a 'dissociation' between morphological and biochemical differentiation. Forskolin also had differential effects on cell viability (MTT reduction test) and proliferation (Ki67 immunostaining with MIB-1 monoclonal antibody), both decreasing in BeWo and increasing in JEG-3 cells. TNFalpha increased apoptosis (cytokeratin neo-epitope immunostaining with M30 monoclonal antibody) in both cell types, an effect which was blocked by epidermal growth factor selectively in JEG-3 cells.

CONCLUSION

Our results suggest that the differential responses of BeWo and JEG-3 cells to inducers of syncytialization and apoptosis might be related to their fusigenic capacity. Caution is needed when extrapolating results obtained by these models to normal trophoblast populations. However, we speculate that these models can help identify key factors involved in trophoblast differentiation at the placental bed.

Identification of two novel human genes, DIPLA1 and DIPAS, expressed in placenta tissue

Here we report the identification and expression analysis of two novel human genes--DIPLA1 (Differentially expressed in placenta 1) and DIPAS (DIPLA1 Antisense). These genes are located at chromosomal region 9q33.1, in opposite orientations, and are flanked by the pregnancy-associated plasma protein-A (PAPP-A) and astrotactin 2 (ASTN2) genes. The mRNA sequences of both genes contain several upstream AUGs (uAUG) and various potential open reading frames (ORFs). DIPLA1 mRNA is 1.8 kb long and contains a 285 nt ORF coding for a polypeptide designated as replicative senescence up-regulated (RSU) protein. Antisense DIPAS mRNA is 2.7 kb long and contains a 309 nt ORF coding for a protein with partial similitude to the gamma isoform variant of the human Ca(2+)/calmodulin (CaM)-dependent protein kinase II. Both genes are conserved in placental-species and are presumably transcribed from initiator (Inr) promoter elements located at opposite strands. In 20 human normal tissues tested, DIPLA1 mRNA expression was placenta-specific, whereas DIPAS mRNA expression was higher in placenta, brain, kidney and testis. In addition, DIPAS mRNA hybridizes with the 3'UTR region from PAPP-A mRNA, which spans over 4 kb more than previously reported, forming a potential sense-antisense double stranded RNA (dsRNA) duplex. Our results are of interest for placenta gene expression regulation and for the identification of novel genes in the human genome.