Aberrant methylation of IGF2-AS promoter in early pregnancy loss

Male infertility is associated with differential DNA methylation signatures of the imprinted gene GNAS and the non-imprinted gene CEP41

PURPOSE

To investigate whether the DNA methylation profiles of GNAS(20q13.32), MEST(7q32.2), MESTIT1(7q32.2), IGF2(11p15.5), H19 (7q32.2), and CEP41(7q32.2) genes are related to the transcriptomic and epigenomic etiology of male infertility.

METHODS

The DNA methylation levels of spermatozoa were obtained from fertile (n = 30), oligozoospermic (n = 30), and men with normal sperm count (n = 30). The methylation status of each CpG site was categorized as hypermethylated or hypomethylated. Expression levels of target gene transcripts were determined using real-time PCR.

RESULTS

The oligozoospermia showed a higher frequency of hypermethylation at GNASAS 1st, 3rd, and 5th CpG dinucleotides (66.7%, 73.3%, 73.3%) compared to the fertile group (33.3%, 33.3%, 40%, respectively). The normal sperm count exhibited a higher frequency of hypermethylation at the 3rd CpG of CEP41 (46.7%) than the fertile group (16.7%). Normal sperm count was predicted by CEP41 hypermethylation (OR = 1.750, 95%CI 1.038-2.950) and hypermethylation of both CEP41 and GNASAS (OR = 2.389, 95%CI 1.137-5.021). Oligozoospermia was predicted solely by GNASAS hypermethylation (OR = 2.460, 95%CI 1.315-4.603). In sperms with decreased IGF2 expression in the fertile group, we observed hypomethylation in the 2nd CpG of IGF2 antisense (IFG2AS), and hypermethylation in the 1st, 2nd, and 4th CpGs of H19. No significant relationship was found between IGF2 expression and methylation status of IGF2AS and H19 in infertile groups.

CONCLUSION

The disappearance of the relationship between IGF2 expression and IGF2AS and H19 methylations in the infertile group provides new information regarding the disruption of epigenetic programming during spermatogenesis. A better understanding of sperm GNASAS and CEP41 hypermethylation could advance innovative diagnostic markers for male infertility.

Deciphering the Epigenetic Landscape: Placental Development and Its Role in Pregnancy Outcomes

The placenta stands out as a unique, transitory, and multifaceted organ, essential to the optimal growth and maturation of the fetus. Functioning as a vital nexus between the maternal and fetal circulatory systems, it oversees the critical exchange of nutrients and waste. This exchange is facilitated by placental cells, known as trophoblasts, which adeptly invade and remodel uterine blood vessels. Deviations in placental development underpin a slew of pregnancy complications, notably fetal growth restriction (FGR), preeclampsia (PE), recurrent spontaneous abortions (RSA), and preterm birth. Central to placental function and development is epigenetic regulation. Despite its importance, the intricate mechanisms by which epigenetics influence the placenta are not entirely elucidated. Recently, the scientific community has turned its focus to parsing out the epigenetic alterations during placental development, such as variations in promoter DNA methylation, genomic imprints, and shifts in non-coding RNA expression. By establishing correlations between epigenetic shifts in the placenta and pregnancy complications, researchers are unearthing invaluable insights into the biology and pathophysiology of these conditions. This review seeks to synthesize the latest findings on placental epigenetic regulation, spotlighting its crucial role in shaping fetal growth trajectories and development. Through this lens, we underscore the overarching significance of the placenta in the larger narrative of gestational health.

DNA Methylation and Recurrent Pregnancy Loss: A Mysterious Compass?

Recurrent pregnancy loss (RPL) is a common and severe pathological pregnancy, whose pathogenesis is not fully understood. With the development of epigenetics, the study of DNA methylation, provides a new perspective on the pathogenesis and therapy of RPL. The abnormal DNA methylation of imprinted genes, placenta-specific genes, immune-related genes and sperm DNA may, directly or indirectly, affect embryo implantation, growth and development, leading to the occurrence of RPL. In addition, the unique immune tolerogenic microenvironment formed at the maternal-fetal interface has an irreplaceable effect on the maintenance of pregnancy. In view of these, changes in the cellular components of the maternal-fetal immune microenvironment and the regulation of DNA methylation have attracted a lot of research interest. This review summarizes the research progress of DNA methylation involved in the occurrence of RPL and the regulation of the maternal-fetal immune microenvironment. The review provides insights into the personalized diagnosis and treatment of RPL.

Downregulation of lncRNA IGF2-AS-encoded peptide induces trophoblast - cycle arrest

RESEARCH QUESTION

lncRNA IGF2-AS may be related to early pregnancy loss. Does lncRNA IGF2-AS affect trophoblast cell growth? The aim of the present study was to verify that lncRNA IGF2-AS encodes a polypeptide, IGF2-AS-168aa, and to study its role in the pathogenesis of trophoblasts.

DESIGN

A small interfering RNA targeted to the IGF2-AS gene (si-IGF2-AS) was designed and transfected into JEG-3 and JAR cells for in-vitro gene silencing. Quantitative polymerase chain reaction and western blotting were used to determine lncRNA IGF2-AS levels in experimental cells. After IGF2-AS suppression, MTT assay was used to assess cell proliferation and apoptosis was determined by flow cytometry. Target gRNA IGF2-AS-gRNA was designed for knockout conducted the corresponding mRNA. HEK293T cells were transfected with the identified positive clone vectors. Finally, IGF2-AS-168aa was analysed by western blotting after the protein-coding region of the IGF2-AS gene was knocked out by CRISPR/Cas9 gene-editing technology.

RESULTS

lncRNA IGF2-AS and IGF2-AS-168aa were significantly downregulated in JEG-3 and JAR cells transfected with si-IGF2-AS (lncRNA IGF2-AS: JAR: NC versus small interfering RNA (siRNA)-1: P = 0.019 NC versus siRNA-2: P = 0.013; JEG-3: NC versus siRNA-1: P = 0.001 NC versus siRNA-2: P = 0.004) (IGF2-AS-168aa: JAR: NC versus siRNA-1: P = 0.030 NC versus siRNA-2: P = 0.018; JEG-3: NC versus siRNA-1: P = 0.004 NC versus siRNA-2: P = 0.001). IGF2-AS gene was incapable of encoding IGF2-AS-168aa after the coding region was successfully knocked out in HEK293T cells. Flow cytometry and the MTT assay revealed that IGF2-AS gene silencing led to cell cycle block in the G1 phase, markedly decreasing cell proliferation and increasing apoptosis.

CONCLUSION

The IGF2-AS gene encoded a peptide with a potential function in trophoblast cell cycle arrest.

Long non-coding RNA IGF2-AS promotes trophoblast cell proliferation, migration, and invasion by regulating miR-520g/N-cadherin axis

BACKGROUND

Recurrent miscarriage (RM) is a distressing reproductive issue worldwide. Dysfunction of trophoblasts can trigger numerous unfavorable pregnant outcomes such as RM, stillbirth, and fetal malformation.

METHODS

In this text, the roles and molecular basis of long non-coding RNA insulin growth factor 2 antisense (IGF2-AS) in the development of trophoblast cells were further investigated. IGF2-AS, microRNA-520g (miR-520g), and N-cadherin levels were measured by RT-qPCR assay. Cell viability, the number of colonies, cell apoptosis, migration, and invasion were measured by CCK-8 assay, colony formation assay, flow cytometry, transwell migration, and invasion assays, respectively. The relative proteins expression was detected by western blot.

RESULTS

The interaction between miR-520g and IGF2-AS or N-cadherin was tested by bioinformatics prediction analysis, and confirmed by dual-luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay. Our data revealed that IGF2-AS and N-cadherin levels were notably decreased, and miR-520g was strikingly increased in the placentas from RM patients. IGF2-AS overexpression promoted cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and hampered cell apoptosis in trophoblast cells, while IGF2-AS deletion exhibited opposite results. Moreover, miR-520g was a target gene of IGF2-AS and negatively regulated by IGF2-AS. MiR-520g inhibitor enhanced the proliferation, migration, and invasion capability of trophoblast cells, suppressed cell apoptosis, and promoted the EMT process. Moreover, the effects of IGF2-AS overexpression on trophoblast cells were reversed by miR-520g upregulation.

CONCLUSIONS

These findings indicated that IGF2-AS facilitated trophoblast cell proliferation, migration, invasion, EMT, and suppressed cell apoptosis by regulating miR-520g/N-cadherin axis, providing potential biomarkers for RM.