The Role of circRNA-SETD2/miR-519a/PTEN Axis in Fetal Birth Weight through Regulating Trophoblast Proliferation

The role of hsa_circ_0042260/miR-4782-3p/LAPTM4A axis in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a common metabolic condition during pregnancy, posing risks to both mother and fetus. CircRNAs have emerged as important players in various diseases, including GDM. We aimed to investigate the role of newly discovered circRNA, hsa_circ_0042260, in GDM pathogenesis. Using GSE194119 dataset, hsa_circ_0042260 was identified and its expression in plasma, placenta, and HG-stimulated HK-2 cells was examined. Silencing hsa_circ_0042260 in HK-2 cells assessed its impact on cell viability, apoptosis, and inflammation. Bioinformatics analysis revealed downstream targets of hsa_circ_0042260, namely miR-4782-3p and LAPTM4A. The interaction between hsa_circ_0042260, miR-4782-3p, and LAPTM4A was validated through various assays. hsa_circ_0042260 was upregulated in plasma from GDM patients and HG-stimulated HK-2 cells. Silencing hsa_circ_0042260 improved cell viability, suppressed apoptosis and inflammation. Hsa_circ_0042260 interacted with miR-4782-3p, which exhibited low expression in GDM patient plasma and HG-stimulated cells. MiR-4782-3p targeted LAPTM4A, confirmed by additional assays. LAPTM4A expression increased in GDM patient plasma and HG-induced HK-2 cells following hsa_circ_0042260 knockdown or miR-4782-3p overexpression. In rescue assays, inhibition of miR-4782-3p or overexpression of LAPTM4A counteracted the effects of hsa_circ_0042260 downregulation on cell viability, apoptosis, and inflammation. In conclusion, the hsa_circ_0042260/miR-4782-3p/LAPTM4A axis plays a role in regulating GDM progression in HG-stimulated HK-2 cells.

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.

Genome wide identification and characterization of fertility associated novel CircRNAs as ceRNA reveal their regulatory roles in sheep fecundity

Reproductive traits play a vital role in determining the production efficiency of sheep. Maximizing the production is of paramount importance for breeders worldwide due to the growing population. Circular RNAs (circRNAs) act as miRNA sponges by absorbing miRNA activity through miRNA response elements (MREs) and participate in ceRNA regulatory networks (ceRNETs) to regulate mRNA expression. Despite of extensive research on role of circRNAs as miRNA sponges in various species, their specific regulatory roles and mechanism in sheep ovarian tissue are still not well understood. In this study, we performed whole genome sequencing of circRNAs, miRNA and mRNA employing bioinformatic techniques on ovine tissues of two contrasting sheep breeds "Small tail Han (X_LC) and Dolang sheep (D_LC)", which results into identification of 9,878 circRNAs with a total length of 23,522,667 nt and an average length of 2,381.32 nt. Among them, 44 differentially expressed circRNAs (DECs) were identified. Moreover, correlation between miRNA-mRNA and lncRNA-miRNA provided us with to prediction of miRNA binding sites on nine differentially expressed circRNAs and 165 differentially expressed mRNAs using miRanda. miRNA-mRNA and lncRNA-miRNA pairs with negative correlation were selected to determine the ceRNA score along with positively correlated pairs from lncRNA and mRNA network. Integration of ceRNA score and positively correlated pairs exhibit a significant ternary relationship among circRNAs-miRNA-mRNA demonestrated by ceRNA, comprising of 50 regulatory pairs sharring common nodes and predicted potential differentially expressed circRNAs-miRNAs-mRNAs regulatory axis. Based on functional enrichment analysis shortlisted key ceRNA regulatory pairs associated with reproduction including circRNA_3257-novel579_mature-EPHA3, circRNA_8396-novel130_mature-LOC101102473, circRNA_4140- novel34_mature > novel661_mature-KCNK9, and circRNA_8312-novel339_mature-LOC101110545. Furthermore, expression profiling, functional enrichments and qRT-PCR analysis of key target genes infer their implication in reproduction and metabolism. ceRNA target mRNAs evolutionary trajectories, expression profiling, functional enrichments, subcellular localizations following genomic organizations will provide new insights underlying molecular mechanisms of reproduction, and establish a solid foundation for future research. Graphical abstract summarizing the scheme of study.

Non-coding RNAs: The link between maternal malnutrition and offspring metabolism

Early life nutrition is associated with the development and metabolism in later life, which is known as the Developmental Origin of Health and Diseases (DOHaD). Epigenetics have been proposed as an important explanation for this link between early life malnutrition and long-term diseases. Non-coding RNAs (ncRNAs) may play a role in this epigenetic programming. The expression of ncRNAs (such as long non-coding RNA H19, microRNA-122, and circular RNA-SETD2) was significantly altered in specific tissues of offspring exposed to maternal malnutrition. Changes in these downstream targets of ncRNAs lead to abnormal development and metabolism. This review aims to summarize the existing knowledge on ncRNAs linking the maternal nutrition condition and offspring metabolic diseases, such as obesity, type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD).

The Role of Non-Coding RNAs in the Human Placenta

Non-coding RNAs (ncRNAs) play a central and regulatory role in almost all cells, organs, and species, which has been broadly recognized since the human ENCODE project and several other genome projects. Nevertheless, a small fraction of ncRNAs have been identified, and in the placenta they have been investigated very marginally. To date, most examples of ncRNAs which have been identified to be specific for fetal tissues, including placenta, are members of the group of microRNAs (miRNAs). Due to their quantity, it can be expected that the fairly larger group of other ncRNAs exerts far stronger effects than miRNAs. The syncytiotrophoblast of fetal origin forms the interface between fetus and mother, and releases permanently extracellular vesicles (EVs) into the maternal circulation which contain fetal proteins and RNA, including ncRNA, for communication with neighboring and distant maternal cells. Disorders of ncRNA in placental tissue, especially in trophoblast cells, and in EVs seem to be involved in pregnancy disorders, potentially as a cause or consequence. This review summarizes the current knowledge on placental ncRNA, their transport in EVs, and their involvement and pregnancy pathologies, as well as their potential for novel diagnostic tools.

Circular RNAs in Pregnancy and the Placenta

The emerging field of circular RNAs (circRNAs) has identified their novel roles in the development and function of many cancers and inspired the interest of many researchers. circRNAs are also found throughout the healthy body, as well as in other pathological states, but while research into the function and abundance of circRNAs has progressed, our overall understanding of these molecules remains primitive. Importantly, recent studies are elucidating new roles for circRNAs in pregnancy, particularly in the placenta. Given that many of the genes responsible for circRNA production in cancer are also highly expressed in the placenta, it is likely that the same genes act in the production of circRNAs in the placenta. Furthermore, placental development can be referred to as ‘controlled cancer’, as it shares many key signalling pathways and hallmarks with tumour growth and metastasis. Hence, the roles of circRNAs in this field are important to study with respect to pregnancy success but also may provide novel insights for cancer progression. This review illuminates the known roles of circRNAs in pregnancy and the placenta, as well as demonstrating differential placental expressions of circRNAs between complicated and uncomplicated pregnancies.

Circular RNA circ SET domain containing 2 (circSETD2) inhibits hepatocellular carcinoma cell proliferation and invasion in vivo and in vitro

Liver cancer is a common malignant tumor with high incidence and mortality rates. However, a reliable prognostic signature has not yet been confirmed. Circular RNAs (circRNAs) play a role in the development and prognosis of numerous malignancies as well as liver cancer. Therefore, identifying abnormally expressed circRNAs in liver cancer tissue is essential for early diagnosis and treatment. This study found that circular RNA circ SET domain containing 2 (circSETD2) is abnormally expressed in liver cancer tissues, but the role and molecular mechanismsin the occurrence and development of liver cancer are still unclear. The expression level of circSETD2 was evaluated through Quantitative Real-time Polymerase chain reaction (qRT-PCR) in cancerous liver tissues (30 cases), liver cancer cell lines and para-cancerous tissues. Knockdown and overexpression circSETD2 lentiviral vector was constructed and applied to transfect hepatoma cells. Cell Counting Kit-8 (CCK-8), colony formation assay, flow cytometry and Transwell assay were used to examine the effects of circSETD2 overexpression or knockdown on liver cancer migration, invasion, cell cycle and cell proliferation. The tumourigenicity in vivo was utilized to assess the effect of circSETD2 on the proliferation of liver cancer cells. circSETD2 expression is lower in cell lines and liver cancer tissues. circSETD2 knockdown can considerably increase liver cancer cells’ invasion, proliferation and colony formation. While In vitro and in vivo, circSETD2 overexpression shows opposite effect. Western blot showed that circSETD2 knockdown can considerably promote E-cadherin expression and inhibit Vimentin, N-cadherin, matrix metallopeptidase-9 (MMP-9) and MMP-2 expression. These findings improve our understanding of the mechanisms of liver cancer progression and will guide future development of therapeutic strategies against the disease by targeting circ-SETD2.

Emerging roles of circular RNAs in osteoporosis

Osteoporosis is one bone disease characterized with skeletal impairment, bone strength reduced and fracture risk enhanced. The regulation processes of bone metabolism are associated with several factors such as mechanical stimulation, epigenetic regulation and hormones. However, the mechanism of osteoporosis remains unsatisfactory. Increasing high‐throughput RNA sequencing and circular RNAs (circRNAs) microarray studies indicated that circRNAs are differentially expressed in osteoporosis. Growing functional studies further pinpointed specific deregulated expressed circRNAs (e.g., circ_28313, circ_0016624, circ_0006393, circ_0076906 and circ_0048211) for their functions involved in bone metabolism, including bone marrow stromal cells (BMSCs) differentiation, proliferation and apoptosis. Moreover, CircRNAs (circ_0002060, Circ_0001275 and Circ_0001445) may be acted as diagnostic biomarkers for osteoporosis. This review discussed recent progresses in the circRNAs expression profiling analyses and their potential functions in regulating BMSCs differentiation, proliferation and apoptosis.

Functional Role of circRNAs in the Regulation of Fetal Development, Muscle Development, and Lactation in Livestock

circRNAs are a class of endogenous noncoding RNA molecules with closed loop structures. They are mainly responsible for regulating gene expression in eukaryotic cells. With the emergence of high-throughput RNA sequencing (RNA-Seq) and new types of bioinformatics tools, thousands of circRNAs have been discovered, making circRNA one of the research hotspots. Recent studies have shown that circRNAs play an important regulatory role in the growth, reproduction, and formation of livestock products. They can not only regulate mammalian fetal growth and development but also have important regulatory effects on livestock muscle development and lactation. In this review, we briefly introduce the putative biogenic pathways and regulatory functions of circRNA and highlight our understanding of circRNA and its latest advances in fetal development, muscle development, and lactation biogenesis as well as expression in livestock. This review will provide a theoretical basis for the research and development of related industries.