Altered expressions and DNA methylation of imprinted genes in chromosome 7 in brain of mouse offspring conceived from in vitro maturation

Identification of key regulatory molecules in the early development stage of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, the incidence of which increases with age, and the pathological changes in the brain are irreversible. Recent studies have highlighted the essential role of long noncoding RNAs (lncRNAs) in AD by acting as competing endogenous RNAs (ceRNAs). Our aim was to construct lncRNA-associated ceRNA regulatory networks composed of potential biomarkers for the early stage of AD. AD related datasets come from AlzData and GEO databases. The R package 'Limma' identifies differentially expressed genes (DEGs), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases for functional enrichment analysis. Protein-protein interactions (PPIs) in DEGs were constructed in the STRING database, and Cytoscape software identified DEGs. Convergent functional genomics (CFG) analysis of differentially expressed hub genes (referred to as early-DEGs) in the brain before the development of AD pathology. The AlzData database analyses the expression levels of early-DEGs in different nerve cells. The lncRNA-miRNA-mRNA regulatory network was established according to the ceRNA hypothesis. We identified four lncRNAs (XIST, NEAT1, KCNQ1OT1 and HCG18) and four miRNAs (hsa-let-7c-5p, hsa-miR-107, hsa-miR-129-2-3p and hsa-miR-214-3p) were preliminarily identified as potential biomarkers for early AD, competitively regulating Atp6v0b, Atp6v1e1 Atp6v1f and Syt1. This study indicates that NEAT1, XIST, HCG18 and KCNQ1OT1 act as ceRNAs in competitive binding with miRNAs to regulate the expression of Atp6v0b, Atp6v1e1, Atp6v1f and Syt1 before the occurrence of pathological changes in AD.

Increased hepatic INSIG-SCAP-SREBP expression is associated with cholesterol metabolism disorder in assisted reproductive technology-conceived aged mice

Although most children conceived by assisted reproductive technology (ART) are healthy, there are concerns regarding the potential long-term health implications of ART. It has been reported that alterations in insulin-induced gene (INSIG), sterol regulatory element binding protein (SREBP), and SREBP cleavage-activating protein (SCAP) are involved in cardiometabolic changes. Thus, ART mouse models were established via in vitro fertilization (IVF), intracytoplasmic injection (ICSI), and in vitro oocyte maturation (IVM). A significantly higher systolic blood pressure was identified in the IVM aged female mice. In addition, abnormalities in the blood lipids and liver function were identified in the IVM- or ICSI-conceived elderly mice. Furthermore, ICSI or IVM significantly affected the hepatic expression and methylation of INSIG-SCAP-SREBP from a young to old age. Our animal data indicated that ICSI or IVM result in a higher risk of cholesterol metabolism dysfunction in older mice, which may be associated with long-term alterations of INSIG-SCAP-SREBP.

Altered methylations of H19, Snrpn, Mest and Peg3 are reversible by developmental reprogramming in kidney tissue of ICSI-derived mice

Although the prevalence of Intracytoplasmic sperm injection (ICSI) has increased year by year, there remains concern about the safety of these procedures because of reports of the increased risk for imprinting disorders. Previous research has demonstrated that gonadotropin stimulation contributes to an increased incidence of epimutations in ICSI-derived mice. However, the epimutations in ICSI offspring after removing the effect of gonadotropin stimulation and the possibility that epimutations are reversible by developmental reprogramming has not been investigated. Our study is the first to investigate the effect of ICSI itself on methylation and exclude the effect of superovulation using the kidney tissues from the adult and old mice. We found reduced methylation and up-regulated expression of the imprinted genes, H19, Mest and Peg3, in adult ICSI mice, but the above alterations observed in adult mice were not detected in old ICSI mice. At the Snrpn DMR, methylation status was not altered in adult ICSI-derived mice, but hypermethylation and correlated down-regulated expression of Snrpn were observed in old mice. In conclusion, ICSI manipulation and early embryo culture resulted in alterations of methylation in differentially methylated region of H19, Mest, Peg3 and Snrpn, and the alterations were reprogrammed by developmental reprogramming.

DNA methylation reprogramming during oogenesis and interference by reproductive technologies: Studies in mouse and bovine models

The use of assisted reproductive technology (ART) to overcome fertility problems has continued to increase since the birth of the first baby conceived by ART over 30 years ago. Similarly, embryo transfer is widely used as a mechanism to advance genetic gain in livestock. Despite repeated optimisation of ART treatments, pre- and postnatal outcomes remain compromised. Epigenetic mechanisms play a fundamental role in successful gametogenesis and development. The best studied of these is DNA methylation; the appropriate establishment of DNA methylation patterns in gametes and early embryos is essential for healthy development. Superovulation studies in the mouse indicate that specific ARTs are associated with normal imprinting establishment in oocytes, but abnormal imprinting maintenance in embryos. A similar limited impact of ART on oocytes has been reported in cattle, whereas the majority of embryo-focused studies have used cloned embryos, which do exhibit aberrant DNA methylation. The present review discusses the impact of ART on oocyte and embryo DNA methylation with regard to data available from mouse and bovine models.

Inter-generational effects of the in vitro maturation technique on pregnancy outcomes, early development, and cognition of offspring in mouse model

In vitro maturation (IVM) of oocytes has been a highly successful method for avoiding the occurrence of severe ovarian hyperstimulation syndrome in some patients during in vitro fertilization. However, the safety of the protocol, especially the long-term effects, is still an issue of debate. The current study is to investigate the long-term effects of IVM on mice through two generations and reveal its inter-generational effects as well. The data indicate that the rates of embryo resorption and fetal death in the F1 generation were significantly increased while the newborn survival rate in the F1 and F2 generations were significantly decreased in the IVM group. Increased body weights in the F1 generation and mouse number per litter in the F2 generation were observed in both the IVM and VVM groups; however, no insulin resistance was detected. No significant differences were detected in birth defects, organ weights, testis histology and sperm motility, estrous cycle, and cognition among the IVM, VVM and N mice in either the F1 or F2 generations. Our results suggest that mouse IVM can affect pregnancy outcomes throughout two generations. IVM does not appear to influence the development and cognition of the offspring throughout two generations.

Long-term follow-up of children conceived through assisted reproductive technology

Children conceived via assisted reproductive technologies (ART) are nowadays a substantial proportion of the population. It is important to follow up these children and evaluate whether they have elevated health risks compared to naturally conceived (NC) children. In recent years there has been a lot of work in this field. This review will summarize what is known about the health of ART-conceived children, encompassing neonatal outcomes, birth defects, growth and gonadal developments, physical health, neurological and neurodevelopmental outcomes, psychosocial developments, risk for cancer, and epigenetic abnormalities. Most of the children conceived after ART are normal. However, there is increasing evidence that ART-conceived children are at higher risk of poor perinatal outcome, birth defects, and epigenetic disorders, and the mechanism(s) leading to these changes have not been elucidated. Continuous follow-up of children after ART is of great importance as they progress through adolescence into adulthood, and new ART techniques are constantly being introduced.