Comprehensive circRNA expression profile during ischemic postconditioning attenuating hepatic ischemia/reperfusion injury

CircRNA-Phf21a_0002 promotes pyroptosis to aggravate hepatic ischemia/ reperfusion injury by sponging let-7b-5p

Hepatic ischemia‒reperfusion injury is a common injury in liver surgery and liver transplantation that can lead to liver function damage, including oxidative stress, apoptosis, autophagy and inflammatory reactions. Pyroptosis is a type of inflammatory programmed cell death that has been implicated in ischemia‒reperfusion injury-associated inflammatory reactions. Although circular RNAs can regulate cell death in hepatic ischemia‒reperfusion injury, their relationship with pyroptosis remains unclear. Therefore, this study aimed to investigate the effect of circular RNA on pyroptosis in hepatic ischemia‒reperfusion injury. We constructed a mouse hepatic ischemia‒reperfusion injury model for circular RNA sequencing and obtained 40 circular RNAs with significant differential expression, of which 39 were upregulated and 1 was downregulated. Subsequently, the endogenous competitive RNA network was constructed using TarBase, miRTarBase, TargetScan, RNAhybrid, and miRanda. Gene Set Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology functional analyses of downstream target genes revealed that circRNA-Phf21a_0002 might affect pyroptosis by regulating the mTOR signaling pathway and Bach1 by sponging let-7b-5p. The overexpression plasmid upregulated the expression of circRNA-Phf21a_0002 in a hypoxia/reoxygenation model, which aggravated pyroptosis in AML12 cells and apoptosis and necrosis of hepatocytes. Next, we investigated the underlying mechanism and found that circRNA-Phf21a_0002 enabled the expression of Bach1 through sponging of let-7b-5p. The aggravation of pyroptosis via overexpression of circRNA-Phf21a_0002 was reversed by let-7b-5p mimics in hypoxia/reoxygenation-subjected AML12 cells. Collectively, our study clarifies that circRNA-Phf21a_0002 aggravates the pyroptosis of hepatocytes related to ischemia-reperfusion by sponging let-7b-5p. These findings provide new molecular mechanisms and novel biomarkers for follow-up treatment.

Identification of Plasma hsa_circ_0001230 and hsa_circ_0023879 as Potential Novel Biomarkers for Focal Segmental Glomerulosclerosis and circRNA-miRNA-mRNA Network Analysis

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is a common glomerulopathy with an unclear mechanism. The demand for FSGS clinical diagnostic biomarkers has not yet been met. Circular RNA (circRNA) is a novel non-coding RNA with multiple functions, but its diagnostic value for FSGS remains unexplored. This study aimed to identify circRNAs that could aid in early clinical diagnosis and to investigate their mechanisms in podocyte injury.

METHODS

The signature of plasma circRNAs for FSGS was identified by circRNA microarray. The existence of circRNAs was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR), RNase R assay, and DNA sequencing. Plasma levels of circRNAs were evaluated by qRT-PCR. The diagnostic value was appraised by the receiver operating characteristic curve. The circRNA-miRNA-mRNA network was built with Cytoscape 7.3.2. Statistically significant differences were calculated by the Mann-Whitney U test.

RESULTS

A total of 493 circRNAs (165 upregulated, 328 downregulated) were differentially expressed in the plasma of FSGS patients (n = 3) and normal controls (n = 3). Eight candidate circRNAs were demonstrated to be circular and stable transcripts. Among them, hsa_circ_0001230 and hsa_circ_0023879 were significantly upregulated in FSGS patients (n = 29) compared to normal controls (n = 51). The areas under the curve value of hsa_circ_0001230 and hsa_circ_0023879 were 0.668 and 0.753, respectively, while that of the two-circRNA panel was 0.763. The RNA pull-down analysis revealed that hsa_circ_0001230 and hsa_circ_0023879 could sponge hsa-miR-106a. Additionally, hsa_circ_0001230 and hsa_circ_0023879 positively regulated hsa-miR-106a target genes phosphatase and tensin homolog (PTEN) and Bcl-2-like protein 11 (BCL2L11) in podocytes.

CONCLUSION

hsa_circ_0001230 and hsa_circ_0023879 are novel blood biomarkers for FSGS. They may regulate podocyte apoptosis by competitively binding to hsa-miR-106a.

Circular RNAs: An emerging precise weapon for diabetic nephropathy diagnosis and therapy

Diabetic nephropathy (DN) is a prevalent chronic microvascular complication associated with diabetes mellitus and represents a major cause of chronic kidney disease and renal failure. Current treatment strategies for DN primarily focus on symptom alleviation, lacking effective approaches to halt or reverse DN progression. Circular RNA (circRNA), characterized by a closed-loop structure, has emerged as a novel non-coding RNA regulator of gene expression, attributed to its conservation, stability, specificity, and multifunctionality. Dysregulation of circRNA expression is closely associated with DN progression, whereby circRNA impacts kidney cell injury by modulating cell cycle, differentiation, cell death, as well as influencing the release of inflammatory factors and stromal fibronectin expression. Consequently, circRNA is considered a predictive biomarker and a potential therapeutic target for DN. This review provides an overview of the latest research progress in the classification, functions, monitoring methods, and databases related to circRNA. The paper focuses on elucidating the impact and underlying mechanisms of circRNA on kidney cells under diabetic conditions, aiming to offer novel insights into the prevention, diagnosis, and treatment of DN.

Non-coding RNAs: The potential biomarker or therapeutic target in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) is the major complication of liver surgery and liver transplantation, that may increase the postoperative morbidity, mortality, tumor progression, and metastasis. The underlying mechanisms have been extensively investigated in recent years. Among these, oxidative stress, inflammatory responses, immunoreactions, and cell death are the most studied. Non-coding RNAs (ncRNAs) are defined as the RNAs that do not encode proteins, but can regulate gene expressions. In recent years, ncRNAs have emerged as research hotspots for various diseases. During the progression of HIRI, ncRNAs are differentially expressed, while these dysregulations of ncRNAs, in turn, have been verified to be related to the above pathological processes involved in HIRI. ncRNAs mainly contain microRNAs, long ncRNAs, and circular RNAs, some of which have been reported as biomarkers for early diagnosis or assessment of liver damage severity, and as therapeutic targets to attenuate HIRI. Here, we briefly summarize the common pathophysiology of HIRI, describe the current knowledge of ncRNAs involved in HIRI in animal and human studies, and discuss the potential of ncRNA-targeted therapeutic strategies. Given the scarcity of clinical trials, there is still a long way to go from pre-clinical to clinical application, and further studies are needed to uncover their potential as therapeutic targets.

Circ_0001052 promotes cardiac hypertrophy via elevating Hipk3

Cardiac hypertrophy (CH) is a crucial risk factor for sudden death. Circular RNAs (circRNAs) exert significant effects in various biological and pathological processes. Circ_0001052 is sourced from Hipk3 (homeodomain-interacting protein kinase 3) and is reported to aggravate myocardial fibrosis. The purpose of the current study was to clarify the role and mechanism of circ-Hipk3 in CH. Transverse aortic constriction (TAC) was used to create an in vivo CH model, and angiotensin II (Ang II) therapy was used to create an in vitro CH model in cardiomyocytes (CMs). It was uncovered that circ_0001052 exerted pro-hypertrophic effects in Ang II-treated CMs. Next, the circular characteristics of circ_0001052 were verified, and we identified that circ_0001052 positively regulated Hipk3. Hipk3 exerted the same functions as circ_0001052 did. It is significant to note that circ_0001052 acted as the ceRNA of Hipk3 by sponging miR-148a-3p and miR-124-3p. According to rescue assays, miR-148a-3p and miR-124-3p partially reversed the effects of circ_0001052. Further, we testified that circ_0001052 recruited Srsf1 to stabilize Hipk3. Finally, rescue assays demonstrated that circ_0001052 promoted CH via up-regulation of Hipk3. In conclusion, our work unveiled that circ_0001052 promoted hypertrophic effects through elevating Hipk3 via sponging miR-148a-3p and miR-124-3p and recruiting Srsf1.

The Novel MyD88 Inhibitor TJ-M2010-5 Protects Against Hepatic Ischemia-reperfusion Injury by Suppressing Pyroptosis in Mice

BACKGROUND

. With the development of medical technology and increased surgical experience, the number of patients receiving liver transplants has increased. However, restoration of liver function in patients is limited by the occurrence of hepatic ischemia-reperfusion injury (IRI). Previous studies have reported that the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway and pyroptosis play critical roles in the development of hepatic IRI.

METHODS

. A mouse model of segmental (70%) warm hepatic IRI was established using BALB/c mice in vivo. The mechanism underlying inflammation in mouse models of hepatic IRI was explored in vitro using lipopolysaccharide- and ATP-treated bone marrow-derived macrophages. This in vitro inflammation model was used to simulate inflammation and pyroptosis in hepatic IRI.

RESULTS

. We found that a MyD88 inhibitor conferred protection against partial warm hepatic IRI in mouse models by downregulating the TLR4/MyD88 signaling pathway. Moreover, TJ-M2010-5 (a novel MyD88 inhibitor, hereafter named TJ-5) reduced hepatic macrophage depletion and pyroptosis induction by hepatic IRI. TJ-5 treatment inhibited pyroptosis in bone marrow-derived macrophages by reducing the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells, decreasing the release of high-mobility group box-1, and promoting endocytosis of lipopolysaccharide-high-mobility group box-1 complexes.

CONCLUSIONS

. Inhibition of MyD88 may protect the liver from partial warm hepatic IRI by reducing pyroptosis in hepatic innate immune cells. These results reveal the mechanism underlying the development of inflammation in partially warm hepatic IRI and the induction of cell pyroptosis.

An Overview of the Advances in Research on the Molecular Function and Specific Role of Circular RNA in Cardiovascular Diseases

In recent years, the rate of residents suffering from cardiovascular disease (CVD), disability, and death has risen significantly. The latest report on CVD in China shows that it still has the highest mortality rate of all diseases in that country. Different from linear RNA, circular RNA (circRNA) is a covalently closed transcript, mainly through reverse splicing so that the 3′end and the 5′end are covalently connected to form a closed loop structure. It is structurally stable and abundant and has distinct tissue or cell specificity, and it is widely distributed in eukaryotes. Although circRNAs were discovered many years ago, researchers have only recently begun to slowly discover their extensive expression and regulatory functions in various biological processes. Studies have found that some circRNAs perform multiple functions in cells more used as RNA binding protein or microRNA sponge. In addition, accumulating evidence shows that the first change that occurs in patients with various metabolic diseases such as hypertension and cardiovascular disease is dysregulated circRNA expression. For cardiovascular and other related blood vessels, circRNA is one of the important causes of various complications. These findings contribute to a more comprehensive understanding and grasp of CVD, and the related molecular mechanisms of CVD should be further analyzed. Here, we review the new understanding of circRNAs in CVD and explain the role of these innovative biomarkers in the analysis and determination of other related cardiovascular events such as coronary heart disease. Thus, this study is aimed at providing new ideas and proposing more feasible medical research strategies based on circRNA.

Hepatoprotective effects of sevoflurane against hepatic ischemia-reperfusion injury by regulating microRNA-124-3p-mediated TRAF3/CREB axis

The purpose of the present study is to define the role of sevoflurane (SEV) in hepatic ischemia-reperfusion (I/R) injury as well as its underlying mechanism. Initially, hepatic I/R animal models and I/R hepatocyte models were established in C57BL/6 mice and normal mouse hepatocytes (BNL CL.2) after SEV preconditioning, respectively, followed by detection of microRNA-124-3p (miR-124-3p), TRAF3, and CREB expression by RT-qPCR and Western blot analysis. In addition, miR-124-3p, TRAF3 and CREB expression in hepatocytes was altered to identify their roles in modulating the levels of glutathione transferase (GST), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and inflammation-related factors and hepatocyte apoptosis by ELISA and flow cytometry respectively. The effects of SEV on the miR-124-3p/TRAF3/CREB axis were also verified in vitro and in vivo. IP assay was performed to verify the effect of TRAF3 on CREB ubiquitination in BNL CL.2 cells, and the cycloheximide (CHX) intervention experiment to detect the stability of CREB protein. SEV augmented the miR-124-3p expression in I/R animal and cell models. Moreover, SEV was observed to suppress I/R-induced liver damage, GST, ALT, and AST levels, hepatocyte apoptosis and inflammation. Overexpression of miR-124-3p resulted in alleviation of hepatic I/R injury, which was countered by TRAF3 overexpression. miR-124-3p targeted TRAF3, while TRAF3 promoted CREB ubiquitination and reduced protein stability of CREB. SEV could impede I/R-induced liver damage, GST, ALT, and AST levels, hepatocyte apoptosis and inflammation via mediation of the miR-124-3p/TRAF3/CREB axis in vitro and in vivo. Collectively, SEV may upregulate miR-124-3p to inhibit TRAF3 expression, thereby reducing the ubiquitination and degradation of CREB, alleviating hepatic I/R injury.

Novel Targets and Therapeutic Strategies to Protect Against Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI), a fascinating topic that has drawn a lot of interest in the last few years, is a major complication caused by a variety of clinical situations, such as liver transplantation, severe trauma, vascular surgery, and hemorrhagic shock. The IRI process involves a series of complex events, including mitochondrial deenergization, metabolic acidosis, adenosine-5'-triphosphate depletion, Kupffer cell activation, calcium overload, oxidative stress, and the upregulation of pro-inflammatory cytokine signal transduction. A number of protective strategies have been reported to ameliorate IRI, including pharmacological therapy, ischemic pre-conditioning, ischemic post-conditioning, and machine reperfusion. However, most of these strategies are only at the stage of animal model research at present, and the potential mechanisms and exact therapeutic targets have yet to be clarified. IRI remains a main cause of postoperative liver dysfunction, often leading to postoperative morbidity or even mortality. Very recently, it was reported that the activation of peroxisome proliferator-activated receptor γ (PPARγ), a member of a superfamily of nuclear transcription factors activated by agonists, can attenuate IRI in the liver, and FAM3A has been confirmed to mediate the protective effect of PPARγ in hepatic IRI. In addition, non-coding RNAs, like LncRNAs and miRNAs, have also been reported to play a pivotal role in the liver IRI process. In this review, we presented an overview of the latest advances of treatment strategies and proposed potential mechanisms behind liver IRI. We also highlighted the role of several important molecules (PPARγ, FAM3A, and non-coding RNAs) in protecting against hepatic IRI. Only after achieving a comprehensive understanding of potential mechanisms and targets behind IRI can we effectively ameliorate IRI in the liver and achieve better therapeutic effects.

Knockdown of circRNA-Memo1 Reduces Hypoxia/Reoxygenation Injury in Human Brain Endothelial Cells Through miRNA-17-5p/SOS1 Axis

Circ-Memo1 has been proved to be upregulated in ischemia-reperfusion induced acute injury of kidney tissues. However, the potential role of circ-Memo1 in cerebral hypoxia/reoxygenation (H/R) injury is still unclear.Blood samples were collected from 25 ischemic stroke patients and 25 healthy controls. To construct the H/R model, human brain microvascular endothelial cells (HBMVECs) were cultured under the hypoxic condition, followed by reoxygenation. Cell viability was analyzed by MTT assay. Flow cytometry was carried out to examine cell apoptosis. The level of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured by MDA and SOD assay kits, respectively. The levels of TNF-α, IL-1β, and IL-6 were determined by enzyme-linked immunosorbent assay (ELISA). Dual-luciferase reporter gene detection was employed to verify the binding relationships between circ-Memo1, miR-17-5p, and SOS1.Circ-Memo1 and SOS1 expressions were increased, and miR-17-5p expression was reduced in ischemic stroke patients. Circ-Memo1 silencing promoted cell viability, inhibited the activation of ERK/NF-κB signaling pathway, reduced oxidative stress and inflammatory response, and inhibited cell apoptosis. Moreover, miR-17-5p functioned as the sponge of circ-Memo1, and SOS1 was identified as the target of miR-17-5p. The protective effect of circ-Memo1 knockdown on cell injury after H/R treatment was weakened by miR-17-5p inhibition.Knockdown of circ-Memo1 alleviated H/R injury of HBMVEC cells by regulating the miR-17-5p/SOS1 axis, indicating that circ-Memo1 might be a potential treatment target for cerebral H/R injury.

CircRNA-MSR Regulates LPS-Induced C28/I2 Chondrocyte Injury through miR-643/MAP2K6 Signaling Pathway

OBJECTIVE

Osteoarthritis (OA) is a degenerative joint disease characterized by deterioration of articular cartilage functions. Previous studies have confirmed the role of circular RNAs (circRNAs) in OA, but the role of mechanical stress-related circRNA (circRNA-MSR) in OA is unknown.

DESIGN

The human chondrocytes C28/I2 were cultured and treated with lipopolysaccharide (LPS) to establish the OA model. The mRNA and protein levels were measured by qRT-PCR or Western blot. Cell viability was analyzed by MTT assay. Flow cytometry was carried out to detect cell apoptosis. The levels of TNF-α, IL-1β, and IL-6 were determined by enzyme-linked immunosorbent assay (ELISA). Pull-down assay was conducted to measure circRNA-MSR-related miRNA. Dual-luciferase reporter gene detection was performed to detect the target relationships between miR-643 and circRNA-MSR or Mitogen-activated protein kinase kinase 6 (MAP2K6). The RNA-fluorescence in situ hybridization (RNA-FISH) assay was conducted to verify the localization of circRNA-MSR and miR-643.

RESULTS

The expressions of circRNA-MSR were upregulated in LPS stimulated C28/I2 cells. Knockdown of circRNA-MSR can inhibit LPS-induced apoptosis, inflammatory response, and extracellular matrix (ECM) degradation, and promote cell C28/I2 cells proliferation. Moreover, circRNA-MSR directly targeted miR-643. RNA-FISH exhibited that circRNA-MSR may act as a competing endogenous RNA (ceRNA) of miR-643. Over-expression of miR-643 could alleviate LPS-induced C28/I2 chondrocyte injury and promote cell proliferation. Besides, miR-643 directly bound to MAP2K6 mRNA. MiR-643 inhibition or MAP2K6 overexpression can reverse the role of circRNA-MSR knockdown on LPS-treated chondrocytes.

CONCLUSION

circRNA-MSR can upregulate MAP2K6 by targeting miR-643, thereby inhibiting cell proliferation and promoting apoptosis of C28/I2 cells.

CircRNA expression profiling of PBMCs from patients with hepatocellular carcinoma by RNA-sequencing

Circular RNAs (circRNAs) are differentially expressed in various cancer types. The present study aimed to investigate the expression and clinical implication of circRNAs in hepatocellular carcinoma (HCC) and to evaluate the potential of circRNAs as diagnostic biomarkers for HCC. CircRNA expression was profiled in 19 patients with HCC and 19 normal controls using ribosomal RNA-depleted RNAs. Differentially expressed circRNAs (DE-circRNAs) between HCC and controls were identified using CIRI2 and distinct circRNA expression signatures were screened. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used to predict the potential functions of these DE-circRNAs and the circRNA-miRNA-mRNA regulatory networks were then constructed. Several DE-circRNAs were selected and confirmed by RT-qPCR. A total of 40 DE-circRNAs (27 upregulated and 13 downregulated) were identified between patients with HCC and controls. Functional annotation indicated that these DE-circRNAs were involved in cellular components, molecular functions and cancer-associated pathways related to HCC. These included pathways in cancer, TNF signaling pathway, hepatitis B, hepatitis C and hepatocyte differentiation. The circRNA-miRNA-mRNA regulatory network was generated based on 11 candidate circRNAs. Receiver operating characteristic curve analysis indicated that Homo sapiens (hsa)_circ_0073239, hsa_circ_007090, hsa_circ_0008304, hsa_circ_0017586, hsa_circ_0000369 and hsa_circ_0001181 may serve as potential biomarkers for HCC. Results from Cell Counting Kit-8 assay suggested that small interfering RNA targeting hsa_circ_0001181 reduced the proliferation of HepG2 cells, which implicated it as a potential therapeutic target for HCC. Therefore, in the present study, the differential expression pattern and important role of circRNAs in HCC were determined. The present results highlight the diagnostic potential of circRNAs in HCC and provide novel insight into the development of and treatment approaches for HCC.

Circular RNA as An Epigenetic Regulator in Chronic Liver Diseases

Circular RNA (circRNA) is a type of non-coding RNA characterized by a covalently closed continuous loop. CircRNA is generated by pre-mRNA through back-splicing and is probably cleared up by extracellular vesicles. CircRNAs play a pivotal role in the epigenetic regulation of gene expression at transcriptional and post-transcriptional levels. Recently, circRNAs have been demonstrated to be involved in the regulation of liver homeostasis and diseases. However, the epigenetic role and underlying mechanisms of circRNAs in chronic liver diseases remain unclear. This review discussed the role of circRNAs in non-neoplastic chronic liver diseases, including alcoholic liver disease (ALD), metabolic-associated fatty liver disease (MAFLD), viral hepatitis, liver injury and regeneration, liver cirrhosis, and autoimmune liver disease. The review also highlighted that further efforts are urgently needed to develop circRNAs as novel diagnostics and therapeutics for chronic liver diseases.

The potential roles of circular RNAs as modulators in traumatic spinal cord injury

Spinal cord injury (SCI) may cause long-term physical impairment and bring a substantial burden to both the individual patient and society. Existing therapeutic approaches for SCI have proven inadequate. This is mainly owing to the incomplete understanding of the cellular and molecular events post-injury. Circular RNAs (circRNAs) represent a new class of non-coding RNAs with a covalently closed annular structure that participates in regulating the transcription of certain genes and are linked to various biological processes and diseases. Mounting evidence is indicative that circRNAs are highly expressed in the spinal cord and they play key roles in multiple processes of neurological diseases. Recently, a role for circRNAs as effectors of SCI has emerged, leading to the continuity of relevant research. In this review, we presented current studies with regards to the abnormality of circRNAs mediating SCI by affecting mechanisms of autophagy, apoptosis, inflammation, and neural regeneration. Furthermore, the potential clinical value of circRNAs as therapeutic targets of SCI was also analyzed.

MiR-124-3p helps to protect against acute respiratory distress syndrome by targeting p65

Background: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury that has a high mortality rate and leads to substantial healthcare costs. MicroRNA-124-3p (miR-124-3p) helps to suppress inflammation during a pulmonary injury. However, its mechanism of action is largely unknown, and its role in ARDS remains to be determined.

Methods: Mice and NR8383 cells were exposed to lipopolysaccharides (LPS) to induce ARDS, and their miR-124-3p levels were determined. After a miRNA agomir was administrated to the mice, their pulmonary injuries were evaluated by H&E staining and assays for peripheral inflammatory cytokine levels. The direct interaction between miR-124-3p and p65 was predicted, and then confirmed by a luciferase activity assay. The role played by miRNA-124-3p in regulating p65 expression was further examined by transfection with its agomir, and its role in cell apoptosis was investigated by observing the effects of miRNA overexpression in vitro and in vivo.

Results: After exposure to LPS, there was a consistent decrease in miR-124-3p expression in the lungs of mice and in NR8383 cells. After treatment with the miR-124-3p agomir, the degrees of pulmonary injury (e.g. alveolar hemorrhage and interstitial edema), and the increases in IL-1β, IL-6, and TNF-α levels induced by LPS were significantly attenuated. Overexpression of miR-124-3p in NC8383 cells and lung tissues significantly suppressed LPS-induced p65 expression and cell apoptosis.

Conclusions: These results suggest that miR-124-3p directly targeted p65, and thereby decreased the levels of inflammation and pulmonary injury in a mouse model of ARDS.

Circular RNA Microarray Analyses in Hepatic Ischemia-Reperfusion Injury With Ischemic Preconditioning Prevention

Ischemic preconditioning (IPC) represents an effective intervention to relieve hepatic ischemia-reperfusion injury (IRI). Systematic detection of circRNA expression revealing the protection effect of IPC still remains to be elucidated. Here, we applied a microarray to detect circRNA and mRNA expression in ischemic liver with and without IPC (n = 3 in each group). Compared with the sham group, there were 39 circRNAs and 432 mRNAs increased and 38 circRNAs and 254 mRNAs decreased (fold change ≥1.5, P < 0.05) in the group of hepatic IRI. As the result of IPC intervention, 43 circRNAs and 64 mRNAs were increased, and 7 circRNAs and 31 mRNAs were decreased in the IPC group when compared with IRI. We then identified circRNA_017753 as the most possible target that may closely relate to IPC protective signaling and predicted Jade1 as the target related to circRNA_017753. Three possible circRNA-miRNA-mRNA axes were constructed that may play a vital role in protective mechanisms in IPC. The study for the first time systematically detects the dysregulated circRNAs and mRNAs in response to hepatic IRI and IPC intervention. Our profile and bioinformatic analysis provide numerous novel clues to understanding the pathophysiologic mechanism of IPC protection against hepatic IRI.

Long Noncoding RNA/Circular RNA-miRNA-mRNA Axes in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) elicits tissue injury involved in a wide range of pathologies. Multiple studies have demonstrated that noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), participate in the pathological development of IRI, and they may act as biomarkers, therapeutic targets, or prognostic indicators. Nonetheless, the specific molecular mechanisms of ncRNAs in IRI have not been completely elucidated. Regulatory networks among lncRNAs/circRNAs, miRNAs, and mRNAs have been the focus of attention in recent years. Studies on the underlying molecular mechanisms have contributed to the discovery of therapeutic targets or strategies in IRI. In this review, we comprehensively summarize the current research on the lncRNA/circRNA-miRNA-mRNA axes and highlight the important role of these axes in IRI.

Inhibition of chikusetsusaponin IVa on inflammatory responses in RAW264.7 cell line via MAPK pathway

Chikusetsusaponin IVa (CHS-IVa), a saponin from herb Panacis japonicas, possesses extensive biological activities. However, the roles and underlying mechanisms of CHS-IVa on inflammation have not been fully clarified in the setting of murine macrophages. In this study, we found that CHS-IVa effectively reduced the expression of inflammatory mediators, including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), interleukin-1β (IL-1β), cyclooxygenase (COX-2), inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-stimulated murine macrophage-like RAW264.7 cells. Meanwhile, CHS-IVa could also evidently bate the contents of nitric oxide (NO) and prostaglandin E2 (PGE2) in cell culture supernatants. Furthermore, the anti-inflammatory activity of CHS-IVa may be via diminishing the phosphorylation of extracellular regulated protein kinases (ERK), p38, and c-Jun N-terminal kinase (JNK). Collectively, these findings will help to understand of the anti-inflammatory effects and mechanisms of P. japonicas deeply, and suggest a validated therapeutic use as an anti-inflammatory medication.

Circular RNA in renal diseases

Circular RNA (circRNA) is a newly described type of non-coding RNA. Active research is greatly enriching the current understanding of the expression and role of circRNA, and a large amount of evidence has implicated circRNA in the pathogenesis of certain renal diseases, such as renal cell carcinoma, acute kidney injury, diabetic nephropathy and lupus nephritis. Studies have found evidence that circRNAs regulate programmed cell death, invasion, and metastasis and serve as biomarkers in renal diseases. Recently, circRNAs were identified in exosomes secreted by the kidneys. Nevertheless, the function of circRNA in renal diseases remains ambiguous. Given that circRNAs are regulators of gene expression, they may be involved in the pathology of multiple renal diseases. Additionally, emerging evidence is showing that circulating circRNAs may serve as novel biomarkers for renal disease. In this review, we have summarized the identification, biogenesis, degradation, and functions of circRNA and have evaluated the roles of circRNA in renal diseases.

Chronic Regulation of miR-124-3p in the Perilesional Cortex after Experimental and Human TBI

Traumatic brain injury (TBI) dysregulates microRNAs, which are the master regulators of gene expression. Here we investigated the changes in a brain-enriched miR-124-3p, which is known to associate with major post-injury pathologies, such as neuroinflammation. RT-qPCR of the rat tissue sampled at 7 d and 3 months in the perilesional cortex adjacent to the necrotic lesion core (aPeCx) revealed downregulation of miR-124-3p at 7 d (fold-change (FC) 0.13, p < 0.05 compared with control) and 3 months (FC 0.40, p < 0.05) post-TBI. In situ hybridization confirmed the downregulation of miR-124-3p at 7 d and 3 months post-TBI in the aPeCx (both p < 0.01). RT-qPCR confirmed the upregulation of the miR-124-3p target Stat3 in the aPeCx at 7 d post-TBI (7-fold, p < 0.05). mRNA-Seq revealed 312 downregulated and 311 upregulated miR-124 targets (p < 0.05). To investigate whether experimental findings translated to humans, we performed in situ hybridization of miR-124-3p in temporal lobe autopsy samples of TBI patients. Our data revealed downregulation of miR-124-3p in individual neurons of cortical layer III. These findings indicate a persistent downregulation of miR-124-3p in the perilesional cortex that might contribute to post-injury neurodegeneration and inflammation.

Circular RNA YAP1 acts as the sponge of microRNA-21-5p to secure HK-2 cells from ischaemia/reperfusion-induced injury

Circular RNA YAP1 (circYAP1) was reported to participate in progression of gastric cancer. However, the role of circYAP1 in acute kidney injury (AKI) remains obscure. We attempted to examine the effects of circYAP1 on ischaemia/reperfusion-stimulated renal injury. AKI model was established by treating HK-2 cells in ischaemia/reperfusion (I/R) environment. CircYAP1 expression in blood of AKI patients and I/R-treated HK-2 cells was evaluated via RT-qPCR. CCK-8, flow cytometry, ELISA and ROS assay were executed to test the impact of circYAP1 on cell viability, apoptosis, inflammatory cytokines and ROS generation. Bioinformatic analysis was executed to explore miRNA targets. The relativity between circYAP1 and miR-21-5p was verified by RT-qPCR and luciferase assay. The functions of miR-21-5p in I/R-triggered injury were reassessed. PI3K/AKT/mTOR pathway was detected by Western blot. Down-regulated circYAP1 was observed in AKI blood samples and I/R-treated HK-2 cells. CircYAP1 overexpression expedited cell growth and weakened secretion of inflammatory factors and ROS generation in I/R-disposed cells. Besides, we found circYAP1 could sponge to miR-21-5p. Interestingly, miR-21-5p overexpression overturned the repressive effects of circYAP1 on cell injury. Moreover, PI3K/AKT/mTOR pathway was activated by circYAP1 via inhibiting miR-21-5p. We demonstrated that circYAP1 activated PI3K/AKT/mTOR pathway and secured HK-2 cells from I/R injury via sponging miR-21-5p.

Elevation of circular RNA circ-POSTN facilitates cell growth and invasion by sponging miR-1205 in glioma

Glioma is the most common type of primary intracranial tumor. Dysregulation of circular RNAs (circRNAs) plays a critical role in multiple solid tumors. However, the expression profiles of circRNAs and their functions in glioma have been rarely studied. The current work aims to investigate the clinical significance of a novel circRNA, circ-POSTN, in glioma and explore its biological functions and mechanisms in the progression of glioma. We found that circ-POSTN was highly expressed in glioma tissue samples and cells. High circ-POSTN expression was significantly linked to larger tumor size, higher World Health Organization grades, and shorter overall survival. Furthermore, silencing of circ-POSTN in glioma cells could decrease cell growth, migratory and invasive potential, and induce cell apoptosis in LN229 cells. On the contrary, ectopically expressed circ-POSTN induced the opposite effects in the U251 cell line. By bioinformatic prediction and luciferase reporter assay, we identified that miR-1205 could be sponged by circ-POSTN. Further rescue assays demonstrated that the oncogenic functions of circ-POSTN are partly attributed to its regulation of miR-1205 in glioma cells. Taken together, our data suggest that circ-POSTN plays an oncogenic role in glioma progression and may serve as a novel therapeutic target in this deadly disease.