Characterization of the altered gene expression profile in early porcine embryos generated from parthenogenesis and somatic cell chromatin transfer

Extracellular Vesicles Secreted by Pre-Hatching Bovine Embryos Produced In Vitro and In Vivo Alter the Expression of IFNtau-Stimulated Genes in Bovine Endometrial Cells

The embryo-maternal interaction occurs during the early stages of embryo development and is essential for the implantation and full-term development of the embryo. In bovines, the secretion of interferon Tau (IFNT) during elongation is the main signal for pregnancy recognition, but its expression starts around the blastocyst stage. Embryos release extracellular vesicles (EVs) as an alternative mechanism of embryo-maternal communication. The aim of the study was to determine whether EVs secreted by bovine embryos during blastulation (D5-D7) could induce transcriptomic modifications, activating IFNT signaling in endometrial cells. Additionally, it aims to assess whether the EVs secreted by embryos produced in vivo (EVs-IVV) or in vitro (EVs-IVP) have different effects on the transcriptomic profiles of the endometrial cells. In vitro- and in vivo-produced bovine morulae were selected and individually cultured for 48 h to collect embryonic EVs (E-EVs) secreted during blastulation. E-EVs stained with PKH67 were added to in vitro-cultured bovine endometrial cells to assess EV internalization. The effect of EVs on the transcriptomic profile of endometrial cells was determined by RNA sequencing. EVs from both types of embryos induced several classical and non-classical IFNT-stimulated genes (ISGs) and other pathways related to endometrial function in epithelial endometrial cells. Higher numbers of differentially expressed genes (3552) were induced by EVs released by IVP embryos compared to EVs from IVV (1838). Gene ontology analysis showed that EVs-IVP/IVV induced the upregulation of the extracellular exosome pathway, the cellular response to stimulus, and the protein modification processes. This work provides evidence regarding the effect of embryo origin (in vivo or in vitro) on the early embryo-maternal interaction mediated by extracellular vesicles.

Unveiling how vitrification affects the porcine blastocyst: clues from a transcriptomic study

Background

Currently, there is a high demand for efficient pig embryo cryopreservation procedures in the porcine industry as well as for genetic diversity preservation and research purposes. To date, vitrification (VIT) is the most efficient method for pig embryo cryopreservation. Despite a high number of embryos survives in vitro after vitrification/warming procedures, the in vivo embryo survival rates after embryo transfer are variable among laboratories. So far, most studies have focused on cryoprotective agents and devices, while the VIT effects on porcine embryonic gene expression remained unclear. The few studies performed were based on vitrified/warmed embryos that were cultured in vitro (IVC) to allow them to re–expand. Thus, the specific alterations of VIT, IVC, and the cumulative effect of both remained unknown. To unveil the VIT-specific embryonic alterations, gene expression in VIT versus (vs.) IVC embryos was analyzed. Additionally, changes derived from both VIT and IVC vs. control embryos (CO) were analyzed to confirm the VIT embryonic alterations. Three groups of in vivo embryos at the blastocyst stage were analyzed by RNA–sequencing: (1) VIT embryos (vitrified/warmed and cultured in vitro), (2) IVC embryos and (3) CO embryos.

Results

RNA–sequencing revealed three clearly different mRNA profiles for VIT, IVC and CO embryos. Comparative analysis of mRNA profiles between VIT and IVC identified 321, differentially expressed genes (DEG) (FDR < 0.006). In VIT vs. CO and IVC vs. CO, 1901 and 1519 DEG were found, respectively, with an overlap of 1045 genes. VIT-specific functional alterations were associated to response to osmotic stress, response to hormones, and developmental growth. While alterations in response to hypoxia and mitophagy were related to the sum of VIT and IVC effects.

Conclusions

Our findings revealed new insights into the VIT procedure-specific alterations of embryonic gene expression by first comparing differences in VIT vs. IVC embryos and second by an integrative transcriptome analysis including in vivo control embryos. The identified VIT alterations might reflect the transcriptional signature of the embryo cryodamage but also the embryo healing process overcoming the VIT impacts. Selected validated genes were pointed as potential biomarkers that may help to improve vitrification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-021-00672-1.

Transcriptome dynamics in early in vivo developing and in vitro produced porcine embryos

BACKGROUND

The transcriptional changes around the time of embryonic genome activation in pre-implantation embryos indicate that this process is highly dynamic. In vitro produced porcine blastocysts are known to be less competent than in vivo developed blastocysts. To understand the conditions that compromise developmental competence of in vitro embryos, it is crucial to evaluate the transcriptional profile of porcine embryos during pre-implantation stages. In this study, we investigated the transcriptome dynamics in in vivo developed and in vitro produced 4-cell embryos, morulae and hatched blastocysts.

RESULTS

In vivo developed and in vitro produced embryos displayed largely similar transcriptome profiles during development. Enriched canonical pathways from the 4-cell to the morula transition that were shared between in vivo developed and in vitro produced embryos included oxidative phosphorylation and EIF2 signaling. The shared canonical pathways from the morula to the hatched blastocyst transition were 14-3-3-mediated signaling, xenobiotic metabolism general signaling pathway, and NRF2-mediated oxidative stress response. The in vivo developed and in vitro produced hatched blastocysts further were compared to identify molecular signaling pathways indicative of lower developmental competence of in vitro produced hatched blastocysts. A higher metabolic rate and expression of the arginine transporter SLC7A1 were found in in vitro produced hatched blastocysts.

CONCLUSIONS

Our findings suggest that embryos with compromised developmental potential are arrested at an early stage of development, while embryos developing to the hatched blastocyst stage display largely similar transcriptome profiles, irrespective of the embryo source. The hatched blastocysts derived from the in vitro fertilization-pipeline showed an enrichment in molecular signaling pathways associated with lower developmental competence, compared to the in vivo developed embryos.

Sexual Dimorphisms of Preeclampsia-Dysregulated Transcriptomic Profiles and Cell Function in Fetal Endothelial Cells

Preeclampsia impairs fetoplacental vascular function and increases risks of adult-onset cardiovascular disorders in children born to preeclamptic mothers, implicating that preeclampsia programs fetal vasculature in utero. However, the underlying mechanisms remain elusive. We hypothesize that preeclampsia alters fetal endothelial gene expression and disturbs cytokines- and growth factors-induced endothelial responses. RNA sequencing analysis was performed on unpassaged human umbilical vein endothelial cells (HUVECs) from normotensive and preeclamptic pregnancies. Functional assays for endothelial monolayer integrity, proliferation, and migration were conducted on passage 1 HUVECs from normotensive and preeclamptic pregnancies. Compared with normotensive cells, 926 and 172 genes were dysregulated in unpassaged female and male HUVECs from preeclamptic pregnancies, respectively. Many of these preeclampsia-dysregulated genes are associated with cardiovascular diseases (eg, heart failure) and endothelial function (eg, cell migration, calcium signaling, and endothelial nitric oxide synthase signaling). TNF (tumor necrosis factor)-α-, TGF (transforming growth factor)-β1-, FGF (fibroblast growth factor)-2-, and VEGFA (vascular endothelial growth factor A)-regulated gene networks were differentially disrupted in unpassaged female and male HUVECs from preeclamptic pregnancies. Moreover, preeclampsia decreased endothelial monolayer integrity in responses to TNF-α in both female and male HUVECs. Preeclampsia decreased TGF-β1-strengthened monolayer integrity in female HUVECs, whereas it enhanced FGF-2-strengthened monolayer integrity in male HUVECs. Preeclampsia promoted TNF-α-, TGF-β1-, and VEGFA-induced cell proliferation in female, but not in male HUVECs. Preeclampsia inhibited TNF-α-induced cell migration in female HUVECs, but had an opposite effect on male HUVECs. In conclusion, preeclampsia differentially dysregulates cardiovascular diseases- and endothelial function-associated genes/pathways in female and male fetal endothelial cells in association with the sexual dimorphisms of preeclampsia-dysregulated fetal endothelial function.

Characterization and comparative analyses of transcriptomes of cloned and in vivo fertilized porcine pre-implantation embryos

Somatic cell nuclear transfer (SCNT) is the only method known to rapidly reprogram differentiated cells into totipotent embryos. Most cloned embryos become arrested before implantation and the details of the underlying molecular mechanism remain largely unknown. Dynamic regulation of the transcriptome is a key molecular mechanism driving early embryonic development. Here, we report comprehensive transcriptomic analysis of cloned embryos (from Laiwu and Duroc pigs) and in vivo fertilized embryos (from Duroc pigs) using RNA-sequencing. Comparisons between gene expression patterns were performed according to differentially expressed genes, specific-expressed genes, first-expressed genes, pluripotency genes and pathway enrichment analysis. In addition, we closely analyzed the improperly expressed histone lysine methyltransferases and histone lysine demethylases during cell reprogramming in cloned embryos. In summary, we identified altered gene expression profiles in porcine cloned pre-implantation embryos in comparison to normal in vivo embryos. Our findings provide a substantial framework for further discovery of the epigenetic reprogramming mechanisms in porcine SCNT embryos.

Summary: Comparative transcriptome analyses of cloned and in vivo fertilized pre-implantation embryos: transcriptional defects and reprogramming barriers in porcine somatic cell nuclear reprogramming.

Preeclampsia Downregulates MicroRNAs in Fetal Endothelial Cells: Roles of miR-29a/c-3p in Endothelial Function

CONTEXT

Preeclampsia is a leading cause of fetal and maternal morbidity and mortality during pregnancy. Although the etiology of preeclampsia is unknown, preeclampsia offspring have increased risks of developing cardiovascular disorders in adulthood, implicating that preeclampsia programs fetal vasculature in utero.

OBJECTIVE

We hypothesize that preeclampsia alters expression profiles of endothelial microRNAs (miRNAs) in fetal endothelial cells and disturbs the vascular endothelial growth factor A (VEGFA)- and fibroblast growth factor 2 (FGF2)-induced endothelial function.

DESIGN AND SETTING

Unpassaged (P0) human umbilical vein endothelial cells (HUVECs) were isolated immediately after cesarean-section delivery from normotensive (NT) and preeclamptic (PE) pregnancies. Differentially expressed miRNAs between P0-HUVECs from NT and PE pregnancies were identified using a miRNA polymerase chain reaction (PCR) array and confirmed using reverse transcription quantitative PCR. To determine the function of these differentially expressed miRNAs, miRNAs of interest were knocked down in NT-HUVECs following by cell functional assays.

RESULTS

Sixteen miRNAs, including miR-29a/c-3p, were downregulated in P0-HUVECs from the PE group compared with the NT group. Bioinformatics analysis predicted the PI3K-v-akt murine thymoma viral oncogene homolog 1 (AKT) signaling pathway was dysregulated in P0-HUVECs from the PE group, which was associated with the miR-29a/c-3p downregulation. We further demonstrated that miR-29a/c-3p knockdown inhibited the VEGFA- and FGF2-induced endothelial migration as well as FGF2-induced AKT1 phosphorylation in HUVECs. However, miR-29a/c-3p knockdown did not alter the extracellular signal-regulated kinase 1/2 phosphorylation, cell proliferation, and endothelial monolayer integrity in response to VEGFA and FGF2 in HUVECs.

CONCLUSIONS

Preeclampsia-downregulated miR-29a/c-3p may impair fetal endothelial function by disturbing the FGF2-activated PI3K-AKT signaling pathway, hence inhibiting endothelial cell migration.

The Efficient Derivation of Trophoblast Cells from Porcine In Vitro Fertilized and Parthenogenetic Blastocysts and Culture with ROCK Inhibitor Y-27632

Trophoblasts (TR) are specialized cells of the placenta and play an important role in embryo implantation. The in vitro culture of trophoblasts provided an important tool to investigate the mechanisms of implantation. In the present study, porcine trophoblast cells were derived from pig in vitro fertilized (IVF) and parthenogenetically activated (PA) blastocysts via culturing in medium supplemented with KnockOut serum replacement (KOSR) and basic fibroblast growth factor (bFGF) on STO feeder layers, and the effect of ROCK (Rho-associated coiled-coil protein kinases) inhibiter Y-27632 on the cell lines culture was tested. 5 PA blastocyst derived cell lines and 2 IVF blastocyst derived cell lines have been cultured more than 20 passages; one PA cell lines reached 110 passages without obvious morphological alteration. The derived trophoblast cells exhibited epithelium-like morphology, rich in lipid droplets, and had obvious defined boundaries with the feeder cells. The cells were histochemically stained positive for alkaline phosphatase. The expression of TR lineage markers, such as CDX2, KRT7, KRT18, TEAD4, ELF5 and HAND1, imprinted genes such as IGF2, PEG1 and PEG10, and telomerase activity related genes TERC and TERF2 were detected by immunofluorescence staining, reverse transcription PCR and quantitative real-time PCR analyses. Both PA and IVF blastocysts derived trophoblast cells possessed the ability to differentiate into mature trophoblast cells in vitro. The addition of Y-27632 improved the growth of both PA and IVF blastocyst derived cell lines and increased the expression of trophoblast genes. This study has provided an alternative highly efficient method to establish trophoblast for research focused on peri-implantation and placenta development in IVF and PA embryos.