Danai Georgiadou
@a-star.edu.sg
Research Scientist/ BIOPROCESSING TECHNOLOGY INSTITUTE
A*star
Scopus Publications
Scopus Publications
Hui Hui Wong, Sze Hwee Seet, Michael Maier, Ayse Gurel, Ricardo Moreno Traspas, Cheryl Lee, Shan Zhang, Beril Talim, Abigail Y.T. Loh, Crystal Y. Chia,et al.
Elsevier BV
Hui Hui Wong, Sze Hwee Seet, Michael Maier, Ayse Gurel, Ricardo Moreno Traspas, Cheryl Lee, Shan Zhang, Beril Talim, Abigail Y.T. Loh, Crystal Y. Chia,et al.
Elsevier BV
Danai Georgiadou, Souad Boussata, Remco Keijser, Dianta A. M. Janssen, Gijs B. Afink, and Marie van Dijk
Frontiers Media SA
Mutations in the LINC-HELLP non-coding RNA (HELLPAR) have been associated with familial forms of the pregnancy-specific HELLP syndrome. These mutations negatively affect extravillous trophoblast (EVT) differentiation from a proliferative to an invasive state and disturb the binding of RNA splicing complex proteins PCBP1, PCBP2, and YBX1 to LINC-HELLP. In this study, by using both in vitro and ex vivo experiments, we investigate if these proteins are involved in the regulation of EVT invasion during placentation. Additionally, we study if this regulation is due to alternative mRNA splicing. HTR-8/SVneo extravillous trophoblasts and human first trimester placental explants were used to investigate the effect of siRNA-mediated downregulation of PCBP1, PCBP2, and YBX1 genes on the differentiation of EVTs. Transwell invasion assays and proliferation assays indicated that upon knockdown of PCBP2 and, to a lesser extent, YBX1 and PCBP1, EVTs fail to differentiate toward an invasive phenotype. The same pattern was observed in placental explants where PCBP2 knockdown led to approximately 80% reduction in the number of explants showing any EVT outgrowth. Of the ones that still did show EVT outgrowth, the percentage of proliferating EVTs was significantly higher compared to explants transfected with non-targeting control siRNAs. To further investigate this effect of PCBP2 silencing on EVTs, we performed whole transcriptome sequencing (RNA-seq) on HTR-8/SVneo cells after PCBP2 knockdown. PCBP2 knockdown was found to have minimal effect on mRNA expression levels. In contrast, PCBP2 silencing led to a switch in splicing for a large number of genes with predominant functions in cellular assembly and organization, cellular function and maintenance, and cellular growth and proliferation and the cell cycle. EVTs, upon differentiation, alter their function to be able to invade the decidua of the mother by changing their cellular assembly and their proliferative activity by exiting the cell cycle. PCBP2 appears to be a paramount regulator of these differentiation mechanisms, where its disturbed binding to LINC-HELLP could contribute to dysfunctional placental development as seen in the HELLP syndrome.
Danai Georgiadou, Souad Boussata, Willemijn H. M. Ranzijn, Leah E. A. Root, Sanne Hillenius, Jeske M. bij de Weg, Carolien N. H. Abheiden, Marjon A. de Boer, Johanna I. P. de Vries, Tanja G. M. Vrijkotte,et al.
Springer Science and Business Media LLC
AbstractPreeclampsia is a frequent gestational hypertensive disorder with equivocal pathophysiology. Knockout of peptide hormone ELABELA (ELA) has been shown to cause preeclampsia-like symptoms in mice. However, the role of ELA in human placentation and whether ELA is involved in the development of preeclampsia in humans is not yet known. In this study, we show that exogenous administration of ELA peptide is able to increase invasiveness of extravillous trophoblasts in vitro, is able to change outgrowth morphology and reduce trophoblast proliferation ex vivo, and that these effects are, at least in part, independent of signaling through the Apelin Receptor (APLNR). Moreover, we show that circulating levels of ELA are highly variable between women, correlate with BMI, but are significantly reduced in first trimester plasma of women with a healthy BMI later developing preeclampsia. We conclude that the large variability and BMI dependence of ELA levels in circulation make this peptide an unlikely candidate to function as a first trimester preeclampsia screening biomarker, while in the future administering ELA or a derivative might be considered as a potential preeclampsia treatment option as ELA is able to drive extravillous trophoblast differentiation.
Danai Georgiadou, Souad Boussata, and Marie van Dijk
American Physiological Society
TO THE EDITOR: We read with great interest the article by Zhou and coworkers (10) in American Journal of Physiology–Endocrinology and Metabolism, entitled “ELABELA, as a potential diagnostic biomarker of preeclampsia, regulates abnormally shallow placentation via APJ.” The authors measured levels of the peptide hormone ELABELA in serum and urine of after nonpregnant, and normal and preeclamptic pregnant women. They nicely demonstrate an increase of ELABELA levels upon pregnancy, while in preeclamptic women the serum levels of ELABELA were found to be significantly lower. We were, however, confused by the serum concentrations of ELABELA as measured in this study; levels were all between log 0.5 and log 2.0 ng/ml, converting to concentrations between 3 and 100 ng/ml. When measuring ELABELA levels in serum of pregnant women with a custom ELISA (3), we do obtain levels up to 100 ng/ml, but the majority is much lower, down to 10 pg/ml, and in about half of the samples ELABELA is even undetectable. Based on the results obtained by Zhou et al. (10), we tested the ELABELA ELISA kit by Phoenix Pharmaceuticals as used in this article and measured pregnant serum samples that by our custom ELISA were either after undetectable, around 0.1 ng/ml and around 100 ng/ml. We noted that the kit recommended a sample preparation by peptide extraction, which we also attempted. Interestingly, without sample extraction all our samples gave values ranging between 10 and 150 ng/ml and not following the same pattern of levels as observed by using the custom ELISA. By using the recommended sample extraction, we measured ELABELA levels mirroring the values as found by the custom assay. The method section of the article by Zhou et al. (10) is inconclusive to the fact if the recommended sample extraction was performed; they state that the ELISA kit was used according to the manufacturer’s instructions. However, based on the concentrations they measured, it appears that sample extraction was not undertaken. To our knowledge, in total eight articles (1, 4–10) have so far been published presenting data on circulating ELABELA in human plasma or serum. These articles used ELISA kits from three different companies (Phoenix Pharmaceuticals, Peninsula Laboratories International and Creative Diagnostics), all recommending sample peptide extraction by C18 columns. In two articles (4, 8), the method section indirectly states that sample extraction was not performed. In the remaining papers the use of sample extraction is unclear. It now appears that when comparing ELABELA data obtained using commercial ELISA kits without or with peptide extraction we are actually looking at different appearances of the peptide, of which the latter identifies the same peptide as the custom ELISA without peptide extraction. This fact potentially leads to ambiguous findings like we recently encountered by performing a systematic review on ELABELA levels in preeclamptic pregnancies (2). Hence, in future studies measuring ELABELA by commercial ELISA kits we strongly recommend that the use of peptide extraction is clearly stated so we are not comparing apples and oranges.
Danai Georgiadou, Gijs B. Afink, and Marie van Dijk
Elsevier BV