Interference of Hsa_circ_0003928 Alleviates High Glucose-Induced Cell Apoptosis and Inflammation in HK-2 Cells via miR-151-3p/Anxa2

Circular RNAs and the regulation of gene expression in diabetic nephropathy (Review)

Circular RNAs (circRNAs) are non‑coding single‑stranded covalently closed RNA molecules that are considered important as regulators of gene expression at the transcriptional and post‑transcriptional levels. These molecules have been implicated in the initiation and progression of multiple human diseases, ranging from cancer to inflammatory and metabolic diseases, including diabetes mellitus and its vascular complications. The present article aimed to review the current knowledge on the biogenesis and functions of circRNAs, as well as their role in cell processes associated with diabetic nephropathy. In addition, novel potential interactions between circRNAs expressed in renal cells exposed to high‑glucose concentrations and the transcription factors c‑Jun and c‑Fos are reported.

CircTAOK1 regulates high glucose induced inflammation, oxidative stress, ECM accumulation, and apoptosis in diabetic nephropathy via targeting miR-142-3p/SOX6 axis

BACKGROUND

Diabetic nephropathy (DN) is a complication caused by diabetes. Circular RNAs (circRNAs) are a kind of RNA with a closed circular structure, which has high stability and is involved in many disease-related processes. The mechanism of circRNA TAO kinase 1 (circTAOK1) in the pathogenesis and development of DN is unclear.

METHODS

CircTAOK1, microRNA (miR)-142-3p, and sex-determining region Y-box transcription factor 6 (SOX6) mRNA levels were analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). Cell counting kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to analyze cell proliferation. Cell cycle distribution was detected by flow cytometry. Western blot assay was performed to test B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X (Bax), cleaved-caspase 3, and fibronectin (FN), collagen I (Col I), and collagen IV (Col IV) protein levels. ELISA assay was used to measure interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor (TNF-α) levels. The reactive oxygen species (ROS) and malondialdehyde (MDA) levels and the superoxide dismutase (SOD) activity were assessed by the corresponding kits. And the correlation between miR-142-3p and circTAOK1 or SOX6 was confirmed by dual luciferase reporter assay, RNA immunoprecipitation assay and RNA pull down assay.

RESULTS

CircTAOK1 and SOX6 expression levels were up-regulated, while miR-142-3p expression was down-regulated in DN serum and HG-treated HK-2 cells. Knockdown of circTAOK1 could inhibit cell injury of HG-induced HK-2 cells. The inhibitory effect of circTAOK1 knockdown on HG-induced HK-2 cell injury was restored by miR-142-3p downregulation. CircTAOK1 acted as a sponge for miR-142-3p, and SOX6 was targeted by miR-142-3p. The overexpression of SOX6 could recover the effect of miR-142-3p overexpression on HG-induced HK-2 cell injury. CircTAOK1 regulated the expression of SOX6 by targeting miR-142-3p.

CONCLUSION

CircTAOK1 knockdown inhibited HG-induced HK-2 cell damage in DN by the miR-142-3p/SOX6 axis.

Circ_0068087 knockdown attenuates high-glucose-induced human tubular epithelial cell injury in a microribonucleic acid/progestin and adipoQ receptor 3-dependent manner in diabetic nephropathy

AIMS/INTRODUCTION

Previous studies have shown that circular ribonucleic acid mediates the occurrence of diabetic nephropathy. This study aimed to analyze the effects of circ_0068087 on high-glucose (HG)-induced human kidney 2 (HK2) cell dysfunction.

MATERIALS AND METHODS

Circ_0068087, miR-580-3p, and progestin and adipoQ receptor 3 (PAQR3) expression were detected by quantitative reverse transcription polymerase chain reaction. Cell viability and proliferation were investigated by Cell Counting Kit-8 and EdU assays, respectively. The cell apoptotic rate was assessed by flow cytometry. Inflammatory response was assessed by enzyme-linked immunoassays. Oxidative stress was evaluated by a superoxide dismutase activity assay kit and lipid peroxidation malondialdehyde assay kit. Molecular interaction was identified by dual-luciferase reporter assay.

RESULTS

Circ_0068087 and PAQR3 expression were significantly upregulated in diabetic nephropathy patients. HG treatment inhibited HK2 cell proliferation, but induced cell apoptosis, inflammation, oxidative stress and epithelial-mesenchymal transition by regulating circ_0068087. Circ_0068087 acted as a microribonucleic acid-580-3p (miR-580-3p) sponge, and miR-580-3p targeted PAQR3. Furthermore, circ_0068087 depletion repressed PAQR3 expression through miR-580-3p. MiR-580-3p inhibitors or PAQR3 introduction attenuated circ_0068087 silencing mediated-effects in HG-treated HK2 cells.

CONCLUSION

Circ_0068087 promoted HG-induced HK2 cell injuries by the regulation of the miR-580-3p/PAQR3 pathway.

Sodium butyrate improves mitochondrial function and kidney tissue injury in diabetic kidney disease via the AMPK/PGC-1α pathway

PURPOSE

Investigate the mechanism of how sodium butyrate (NaBut) improves mitochondrial function and kidney tissue injury in diabetic kidney disease (DKD) via the AMPK/PGC-1α pathway.

METHODS

Assess the effects of NaBut on glucose and insulin tolerance, urine, and gut microbial composition in db/db and db/m mice. Use flow cytometry and western blotting to detect the effects of NaBut on apoptosis, kidney mitochondrial function, and AMPK/PGC-1α signaling. Use HK-2 cells induced by high glucose (HG) to establish the DKD model in vitro and detect changes in the AMPK/PGC-1α signaling pathway and mitochondrial function after NaBut intervention.

RESULTS

NaBut attenuated blood glucose levels and reversed increases in urine and serum levels of glucose, BUN, Ucr, TG, TC, and UAE in db/db mice. NaBut improved insulin tolerance, reversed PGC-1α and p-AMPK expression level in the kidneys of db/db mice, and improved lipid accumulation and mitochondrial function. NaBut was able to reverse the effects of elevated glucose, compound C, and siRNA-PGC on ROS and ATP levels. Additionally, it increased protein expression of PGC-1α and p-AMPK.

CONCLUSION

NaBut activates the kidney mitochondrial AMPK/PGC-1α signaling pathway and improves mitochondrial dysfunction in DKD, thus protecting kidney tissue in vitro and in vivo.

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.

Perspectives of circular RNAs in diabetic complications from biological markers to potential therapeutic targets (Review)

Chronic complications of diabetes increase mortality and disability of patients. It is crucial to find potential early biomarkers and provide novel therapeutic strategies for diabetic complications. Circular RNAs (circRNAs), covalently closed RNA molecules in eukaryotes, have high stability. Recent studies have confirmed that differentially expressed circRNAs have a vital role in diabetic complications. Certain circRNAs, such as circRNA ankyrin repeat domain 36, circRNA homeodomain‑interacting protein kinase 3 (circHIPK3) and circRNA WD repeat domain 77, are associated with inflammation, endothelial cell apoptosis and smooth muscle cell proliferation, leading to vascular endothelial dysfunction and atherosclerosis. CircRNA LDL receptor related protein 6, circRNA actin related protein 2, circ_0000064, circ‑0101383, circ_0123996, hsa_circ_0003928 and circ_0000285 mediate inflammation, apoptosis and autophagy of podocytes, mesangial cell hypertrophy and proliferation, as well as tubulointerstitial fibrosis, in diabetic nephropathy by regulating the expression of microRNAs and proteins. Circ_0005015, circRNA PWWP domain containing 2A, circRNA zinc finger protein 532, circRNA zinc finger protein 609, circRNA DNA methyltransferase 3β, circRNA collagen type I α2 chain and circHIPK3 widely affect multiple biological processes of diabetic retinopathy. Furthermore, circ_000203, circ_010567, circHIPK3, hsa_circ_0076631 and circRNA cerebellar degeneration‑related protein 1 antisense are involved in the pathology of diabetic cardiomyopathy. CircHIPK3 is the most well‑studied circRNA in the field of diabetic complications and is most likely to become a biological marker and therapeutic target for diabetic complications. The applications of circRNAs may be a promising treatment strategy for human diseases at the molecular level. The relationship between circRNAs and diabetic complications is summarized in the present study. Of note, circRNA‑targeted therapy and the role of circRNAs as biomarkers may potentially be used in diabetic complications in the future.

Hsa_circ_0003928 regulates the progression of diabetic nephropathy through miR-136-5p/PAQR3 axis

BACKGROUND

Diabetic nephropathy (DN) is one of the complications of diabetes and has a high mortality, but its specific pathogenesis is not clear. In recent years, researches on the mechanism of circRNAs in DN have been proved a lot, whereas the functional mechanism of circ_0003928 in DN remains open and it must be investigated to value its important role in DN prevention.

METHODS

HK-2 cells were treated with high glucose (HG), normal glucose (NG) or Mannitol. Cell counting kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were performed to detect cell proliferation. Enzyme-linked immunosorbent assay (ELISA) was applied to analyze malondialdehyde (MDA) and superoxide dismutase 1 (SOD) levels. Flow cytometry and western blot were preformed to measure cell apoptosis. Real-time quantitative PCR (RT-qPCR) was used to test the levels of circ_0003928, miR-136-5p and progestin and adipoQ receptor family member 3 (PAQR3) mRNA. Western blot was executed to detect Bcl2 associated X (Bax), B cell leukemia/lymphoma 2 (Bcl2), smooth muscle (αSMA), apolipoprotein (C-IV) and PAQR3 levels. Luciferase reporter assay and RNA pull-down assay were used to analyze the target relationship between miR-136-5p and circ_0003928 or PAQR3.

RESULTS

Circ_0003928 and PAQR3 expression were up-regulated, whereas miR-136-5p was decreased in DN serum and HG-induced HK-2 cells. Circ_0003928 knockdown promoted cell proliferation, and inhibit cell apoptosis, oxidative stress, and fibrosis in HK-2 cells under HG condition. MiR-136-5p silencing overturned the protective effects of si-circ_0003928 on HG-induced HK-2 cells. MiR-136-5p was targeted by circ_0003928 and directly targeted PAQR3. Overexpression of PAQR3 counteracted the inhibitory functions of circ_0003928 knockdown or miR-136-5p overexpression on HG-induced HK-2 cell injury.

CONCLUSION

Circ_0003928 acted as a sponge of miR-136-5p to up-regulating PAQR3 expression, and then regulate the proliferation, oxidative stress, fibrosis and apoptosis in HG-induced HK-2 cells.

A Novel Circ_Arf3/miR-452-5p/Mbnl1 Axis Regulates Proliferation and Expression of Fibrosis-Related Proteins of Mouse Mesangial Cells Under High Glucose

Background

Diabetic nephropathy (DN) is a serious microvascular complication of diabetes that may lead to chronic renal failure and end-stage renal disease. Circular RNAs (circRNAs) play important roles in DN progression. However, the action of circRNA ADP ribosylation factor 3 (circ_Arf3) in high glucose (HG)-induced change is still unclear.

Methods

Mouse mesangial cells (MCs) were treated with 30 mM HG as a DN cell model in vitro. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to examine the expression levels of circ_Arf3, microRNA (miR)-452-5p and muscleblind like splicing regulator 1 (Mbnl1). The proliferation of HG-treated MCs was assessed using 5 Ethynyl 2' deoxyuridine (EdU) and cell counting kit-8 (CCK-8) assays, and the levels of proliferation and fibrosis-related proteins and Mbnl1 were detected by Western blot. Dual-luciferase reporter and RNA pull-down assays were utilized to determine the relationship between miR-452-5p and circ_Arf3 or Mbnl1.

Results

Our results discovered that circ_Arf3 and Mbnl1 were lowly expressed in HG-treated MCs, while miR-452-5p expression was up-regulated. Moreover, circ_Arf3 was mainly located in the cytoplasm and had a ring-like stable structure. Functional assays demonstrated that overexpression of circ_Arf3 prevented cell proliferation and fibrous formation in HG-treated MCs. Circ_Arf3 could sponge miR-452-5p, and the effect of circ_Arf3 overexpression was reversed by enhanced expression of miR-452-5p. Mbnl1 was a direct target of miR-452-5p. Knockdown of Mbnl1 abolished the suppressive effects of miR-452-5p inhibitor on proliferation and fibrosis-related protein expression in HG-treated MCs. Moreover, circ_Arf3 regulated Mbnl1 through miR-452-5p.

Conclusion

Overexpression of circ_Arf3 prevents cell proliferation and fibrous formation in HG-treated MCs by regulating the expression of Mbnl1 via miR-452-5p.

Epigenetic modification in diabetic kidney disease

Diabetic kidney disease (DKD) is a common microangiopathy in diabetic patients and the main cause of death in diabetic patients. The main manifestations of DKD are proteinuria and decreased renal filtration capacity. The glomerular filtration rate and urinary albumin level are two of the most important hallmarks of the progression of DKD. The classical treatment of DKD is controlling blood glucose and blood pressure. However, the commonly used clinical therapeutic strategies and the existing biomarkers only partially slow the progression of DKD and roughly predict disease progression. Therefore, novel therapeutic methods, targets and biomarkers are urgently needed to meet clinical requirements. In recent years, increasing attention has been given to the role of epigenetic modification in the pathogenesis of DKD. Epigenetic variation mainly includes DNA methylation, histone modification and changes in the noncoding RNA expression profile, which are deeply involved in DKD-related inflammation, oxidative stress, hemodynamics, and the activation of abnormal signaling pathways. Since DKD is reversible at certain disease stages, it is valuable to identify abnormal epigenetic modifications as early diagnosis and treatment targets to prevent the progression of end-stage renal disease (ESRD). Because the current understanding of the epigenetic mechanism of DKD is not comprehensive, the purpose of this review is to summarize the role of epigenetic modification in the occurrence and development of DKD and evaluate the value of epigenetic therapies in DKD.

TRIM59 attenuates ox-LDL-induced endothelial cell inflammation, apoptosis, and monocyte adhesion through AnxA2

Background

Atherosclerosis (AS), a chronic inflammatory vascular disease, is a cause of heart attack and ischemic stroke. Tripartite motif-containing protein 59 (TRIM59), a member of the tripartite motif family, has been reported to be involved in inflammatory diseases. This study was to investigate the role of TRIM59 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cells and examine the mechanism of TRIM59.

Methods

To simulate a cellular model of AS in vitro, varying concentrations of ox-LDL (i.e., 20, 40, 60, 80, and 100 µg/mL) were used to treat the human umbilical vein endothelial cells (HUVECs) for 24 h. The messenger ribonucleic acid (RNA) and protein levels of TRIM59, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and annexin 2 (AnxA2) were examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. The transfection efficacy of overexpression (Ov)-TRIM59 and small-interfering RNA-AnxA2 was examined by RT-qPCR and western blot. Cell counting kit-8 assays, lactate dehydrogenase (LDH) assays, enzyme-linked immunosorbent assays, and terminal-deoxynucleotidyl transferase mediated nick end labeling staining were used to examine viability, LDH expression, inflammation, and apoptosis in HUVECs. The protein levels of B-cell lymphoma 2, Bcl-2-associated X (BAX), cleaved caspase3, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 were assessed by western blot. Additionally, the adhesion of THP-1 to ox-LDL-induced HUVECs was detected using monocyte adhesion assays and the binding of TRIM59 and AnxA2 was verified by co-immunoprecipitation.

Results

This study showed that TRIM59 expression was decreased in the ox-LDL-induced HUVECs while LOX-1 expression was increased. After transfection with Ov-TRIM59, TRIM59 in ox-LDL-induced HUVECs was increased, and TRIM59 overexpression alleviated the viability damage, inflammation, and apoptosis of the ox-LDL-induced HUVECs. In addition, THP-1 adhesion to the ox-LDL-induced HUVECs was also suppressed by TRIM59 overexpression. This study also showed that TRIM59 could bind to AnxA2 and promote AnxA2 expression in ox-LDL-stimulated HUVECs. Moreover, the rescue experiments revealed that TRIM59 suppressed the viability damage, inflammation, apoptosis, and monocyte adhesion of the ox-LDL-induced HUVECs via AnxA2.

Conclusions

TRIM59 protected against ox-LDL-induced AS by binding to AnxA2.

Specific microRNA Signature Kinetics in Porphyromonas gingivalis-Induced Periodontitis

Porphyromonas gingivalis is one of the major bacteria constituting the subgingival pathogenic polymicrobial milieu during periodontitis. Our objective is to determine the global microRNA (miRNA, miR) expression kinetics in 8- and 16-weeks duration of P. gingivalis infection in C57BL/6J mice and to identify the miRNA signatures at specific time-points in mice. We evaluated differential expression (DE) miRNAs in mandibles (n = 10) using high-throughput NanoString nCounter® miRNA expression panels. The bacterial colonization, alveolar bone resorption (ABR), serum immunoglobulin G (IgG) antibodies, and bacterial dissemination were confirmed. In addition, all the infected mice showed bacterial colonization on the gingival surface, significant increases in ABR (p < 0.0001), and specific IgG antibody responses (p < 0.05-0.001). The miRNA profiling showed 26 upregulated miRNAs (e.g., miR-804, miR-690) and 14 downregulated miRNAs (e.g., miR-1902, miR-1937a) during an 8-weeks infection, whereas 7 upregulated miRNAs (e.g., miR-145, miR-195) and one downregulated miR-302b were identified during a 16-weeks infection. Both miR-103 and miR-30d were commonly upregulated at both time-points, and all the DE miRNAs were unique to the specific time-points. However, miR-31, miR-125b, miR-15a, and miR-195 observed in P. gingivalis-infected mouse mandibles were also identified in the gingival tissues of periodontitis patients. None of the previously identified miRNAs reported in in vitro studies using cell lines (periodontal ligament cells, gingival epithelial cells, human leukemia monocytic cell line (THP-1), and B cells) exposed to P. gingivalis lipopolysaccharide were observed in the in vivo study. Most of the pathways (endocytosis, bacterial invasion, and FcR-mediated phagocytosis) targeted by the DE miRNAs were linked with bacterial pathogen recognition and clearance. Further, eighteen miRNAs were closely associated with the bacterial invasion of epithelial cells. This study highlights the altered expression of miRNA in gingiva, and their expression depends on the time-points of infection. This is the first in vivo study that identified specific signature miRNAs (miR-103 and miR-30d) in P. gingivalis invasion of epithelial cells, establishes a link between miRNA and development of periodontitis and helping to better understand the pathobiology of periodontitis.

Infant Saliva Levels of microRNA miR-151a-3p Are Associated with Risk for Neurodevelopmental Delay

Prompt recognition of neurodevelopmental delay is critical for optimizing developmental trajectories. Currently, this is achieved with caregiver questionnaires whose sensitivity and specificity can be limited by socioeconomic and cultural factors. This prospective study of 121 term infants tested the hypothesis that microRNA measurement could aid early recognition of infants at risk for neurodevelopmental delay. Levels of four salivary microRNAs implicated in childhood autism (miR-125a-5p, miR-148a-5p, miR-151a-3p, miR-28-3p) were measured at 6 months of age, and compared between infants who displayed risk for neurodevelopmental delay at 18 months (n = 20) and peers with typical development (n = 101), based on clinical evaluation aided by the Survey of Wellbeing in Young Children (SWYC). Accuracy of microRNAs for predicting neurodevelopmental concerns at 18 months was compared to the clinical standard (9-month SWYC). Infants with neurodevelopmental concerns at 18 months displayed higher levels of miR-125a-5p (d = 0.30, p = 0.018, adj p = 0.049), miR-151a-3p (d = 0.30, p = 0.017, adj p = 0.048), and miR-28-3p (d = 0.31, p = 0.014, adj p = 0.048). Levels of miR-151a-3p were associated with an 18-month SWYC score (R = -0.19, p = 0.021) and probability of neurodevelopmental delay at 18 months (OR = 1.91, 95% CI, 1.14-3.19). Salivary levels of miR-151a-3p enhanced predictive accuracy for future neurodevelopmental delay (p = 0.010, X² = 6.71, AUC = 0.71) compared to the 9-month SWYC score alone (OR = 0.56, 95% CI, 0.20-1.58, AUC = 0.567). This pilot study provides evidence that miR-151a-3p may aid the identification of infants at risk for neurodevelopmental delay. External validation of these findings is necessary.

Silencing circ_0080425 alleviates high-glucose-induced endothelial cell dysfunction in diabetic nephropathy by targeting miR-140-3p/FN1 axis

BACKGROUND

Hsa_circ_0080425 (circ_0080425) is newly identified to correlate with the progression of diabetic nephropathy (DN). However, its role and mechanism in DN process is not very clear.

METHODS

Cell counting kit-8 assay, flow cytometry, scratch wound assay, and western blotting were performed to measure endothelial cell dysfunction. Expression of circ_0080425, microRNA (miR)-140-3p and fibronectin 1 (FN1) were determined by quantitative real-time PCR and western blotting. The direct interaction was confirmed by dual-luciferase reporter assay.

RESULTS

High-glucose (HG) treatment could induce inhibition of cell proliferation, cell cycle entrance and wound healing rate in human umbilical vein endothelial cells (HRGEC), and enhancement of apoptosis rate. Circ_0080425 expression was upregulated by HG, and exhausting circ_0080425 could attenuate HG-induced above effects in HRGEC. MiR-140-3p was sponged by circ_0080425, and its inhibitor reversed the regulation of circ_0080425 knockdown on HG-induced HRGEC injury. FN1 was targeted by miR-140-3p, and its overexpression also restored the inhibitory effect of miR-140-3p on HC-induced HRGEC injury.

CONCLUSION

Circ_0080425 expression might contribute to HG-induced endothelial cell injury, and circ_0080425/miR-140-3p/FN1 axis was a potential therapeutic approach to interfere DN process.

Circ_0060077 Knockdown Alleviates High-Glucose-Induced Cell Apoptosis, Oxidative Stress, Inflammation and Fibrosis in HK-2 Cells via miR-145-5p/VASN Pathway

The involvement of circular RNAs (circRNAs) in the progression of diabetic nephropathy (DN) has been reported. However, the functions of circ_0060077 in DN remain unclear. HK-2 cells were treated with high glucose (HG) to establish DN cell model. Quantitative real-time polymerase chain reaction (qRT-PCR) was proceeded to determine the levels of circ_0060077, microRNA-145-5p (miR-145-5p) and vasorin (VASN). Cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and colony formation assay were conducted to assess cell proliferation ability. Flow cytometry analysis was employed for cell apoptosis. The oxidative stress level was evaluated by commercial kits. Enzyme-linked immunosorbent assay (ELISA) was adopted to examine the concentrations of inflammatory factors. Western blot assay was utilized for protein levels. Dual-luciferase reporter assay and RNA pull-down assay were manipulated to analyze the relationships among circ_0060077, miR-145-5p and VASN. Circ_0060077 level was increased in DN patients and HG-stimulated HK-2 cells. Circ_0060077 knockdown ameliorated the inhibitory effect of HG on HK-2 cell proliferation and the promotional effects on cell apoptosis, oxidative stress, inflammation and fibrosis. MiR-145-5p was identified as the target for circ_0060077 and miR-145-5p inhibition ameliorated the effect of circ_0060077 silencing on HG-induced HK-2 cell injury. Moreover, miR-145-5p directly bound to VASN. Overexpression of miR-145-5p facilitated cell proliferation and repressed apoptosis, oxidative injury, inflammation and fibrosis in HG-induced HK-2 cells by targeting VASN. Circ_0060077 silencing protected HK-2 cells from HG-induced damage by regulating miR-145-5p/VASN axis.

Identification of Hub Genes Involved in Tubulointerstitial Injury in Diabetic Nephropathy by Bioinformatics Analysis and Experiment Verification

Diabetic nephropathy (DN) is the most important cause of end-stage renal disease with a poorer prognosis and high economic burdens of medical treatments. It is of great research value and clinical significance to explore potential gene targets of renal tubulointerstitial lesions in DN. To properly identify key genes associated with tubulointerstitial injury of DN, we initially performed a weighted gene coexpression network analysis of the dataset to screen out two nonconserved gene modules (dark orange and dark red). The regulation of oxidative stress-induced intrinsic apoptotic signaling pathway, PI3K-Akt signaling pathway, p38MAPK cascade, and Th1 and Th2 cell differentiation were primarily included in Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of these two modules. Next, 199 differentially expressed genes (DEGs) were identified via the limma package. Then, the GO annotation and KEGG pathways of the DEGs were primarily enriched in extracellular matrix (ECM) organization, epithelial cell migration, cell adhesion molecules (CAMs), NF-kappa B signaling pathway, and ECM-receptor interaction. Gene set enrichment analysis showed that in the DN group, the interaction of ECM-receptor, CAMs, the interaction of cytokine-cytokine receptor, and complement and coagulation cascade pathways were significantly activated. Eleven key genes, including ALB, ANXA1, ANXA2, C3, CCL2, CLU, EGF, FOS, PLG, TIMP1, and VCAM1, were selected by constructing a protein-protein interaction network, and expression validation, ECM-related pathways, and glomerular filtration rate correlation analysis were performed in the validated dataset. The upregulated expression of hub genes ANXA2 and FOS was verified by real-time quantitative PCR in HK-2 cells treated with high glucose. This study revealed potential regulatory mechanisms of renal tubulointerstitial damage and highlighted the crucial role of extracellular matrix in DN, which may promote the identification of new biomarkers and therapeutic targets.

TSPAN8 alleviates high glucose-induced apoptosis and autophagy via targeting mTORC2

TSPAN8 mediates signal transduction from extracellular cues and regulates cell development, activation, growth, and motility. However, whether TSPAN8 is involved in the progression of diabetic nephropathy (DN) remains unclear. This study aimed to explore the potential functional roles of TSPAN8 in regulating autophagy and apoptosis of HK-2 cells induced by high glucose (HG). RT-PCR and western blot analysis (WB) were employed to detect TSPAN8 levels in the blood samples of DN patients as well as in HG-induced HK-2 cells. Cell proliferation of HK-2 cells was examined by CCK-8 assay, and apoptosis was analyzed by flow cytometry. The functional role of TSPAN8 was evaluated by the transfection of TSPAN8 expression plasmid. Results showed that TSPAN8 level was significantly reduced in the blood samples of DN patients and HG-induced HK-2 cell lines. TSPAN8 overexpression rescued HG-induced apoptosis in HK-2 cells. TSPAN8 could form a complex with Rictor and mTORC2. TSPAN8 overexpression suppressed HG-induced autophagy in HK-2 cells, which was dependent on mTOR activity. In conclusion, the present study showed that TSPAN8 mitigates HG-induced autophagy and apoptosis in HK-2 cells, which may serve as candidate target for DN treatment.

Circ_0068087 Promotes High Glucose-Induced Human Renal Tubular Cell Injury through Regulating miR-106a-5p/ROCK2 Pathway

<b><i>Background:</i></b> Many studies have confirmed that circular RNA (circRNA) is an important target for regulating human disease progression. This study aimed to explore the role of circ_0068087 in diabetic nephropathy (DN) progression. <b><i>Methods:</i></b> High glucose (HG)-induced renal tubular cells (HK2) were used to mimic DN cell models in vitro. The expression levels of circ_0068087, microRNA (miR)-106a-5p, and Rho-associated coiled-coil-containing kinase 2 (ROCK2) were detected by quantitative real-time PCR. Cell proliferation and apoptosis were examined by cell counting kit-8 assay, 5-ethynyl-2′-deoxyuridine assay, colony formation assay, and flow cytometry. The protein levels were examined by Western blot analysis. Cell oxidative stress was assessed by measuring MDA level and SOD activity, and cell inflammation was evaluated by detecting the concentrations of inflammatory factors. RNA interaction was verified by dual-luciferase reporter assay and RNA pull-down assay. <b><i>Results:</i></b> The present study showed that circ_0068087 was highly expressed in the serum of DN patients and HG-induced HK2 cells. Interference of circ_0068087 alleviated HG-induced apoptosis, oxidative stress, inflammation, and fibrosis in HK2 cells, while accelerated cell proliferation. miR-106a-5p could be sponged by circ_0068087, and its inhibitor eliminated the regulation of circ_0068087 knockdown on HG-induced HK2 cell injury. ROCK2 was a target of miR-106a-5p, and its expression was suppressed by circ_0068087 knockdown. miR-106a-5p overexpression suppressed HG-induced HK2 cell injury, and this effect was reversed by ROCK2 upregulation. <b><i>Conclusion:</i></b> Our data indicated that circ_0068087 downregulation mitigated HG-induced HK2 cell injury through the miR-106a-5p/ROCK2 axis, providing a potential circRNA-targeted therapy for DN.

Circ_0004951 Promotes Pyroptosis of Renal Tubular Cells via the NLRP3 Inflammasome in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) has become the leading cause of chronic kidney disease (CKD) in many countries. Recent studies have shown that circular RNA and pyroptosis play an important role in pathogenesis of DKD.

Methods

We analyzed expression patterns of circRNAs in human kidney biopsy tissues obtained from type 2 DKD (n = 9) and nephrectomy (n = 9) patients. Next, we cultured human renal tubular epithelial cells (HK2) in high glucose condition and detected circ_0004951, miR-93-5p, NLR Pyrin Domain Containing 3 (NLRP3) inflammasome-related indicators and pyroptosis. Furthermore, we performed Bioinformatics analysis and dual-luciferase reporter assay to analyze the relationship among circ_0004951, miR-93-5p and NLRP3.

Results

Circ_0004951 was significantly upregulated in kidney tissues from DKD patients and HK2 in high glucose condition vs. control. Knockdown of circ_0004951 mediated a significant suppression of HK2 pyroptosis, while results from bioinformatics analysis revealed that circ_0004951 has binding sites with miR-93-5p and miR-93-5p could bind to NLRP3. Results from dual-luciferase reporter assay further corroborated this finding. Finally, observations from rescue experiments showed that down-regulation of miR-93-5p and upregulation of NLRP3 markedly attenuated the anti-pyroptosis and anti-inflammatory effects of circ_0004951 knockdown on HK2.

Conclusion

Circ_0004951 promotes pyroptosis of renal tubular epithelial cells in DKD via the miR-93-5p/NLRP3 inflammasome pathway, suggesting its potential for clinical diagnosis and treatment of DKD.

CircNUP98 knockdown alleviates high glucose-induced proliferation, fibrosis, inflammation and oxidative stress in human glomerular mesangial cells by regulating miR-151-3p/HMGA2 axis

PURPOSE

This study aimed to investigate the role and mechanism of circRNA nucleoporin 98 (circNUP98) in Diabetic nephropathy (DN).

METHODS

Human glomerular mesangial cells (HMCs) were stimulated with high glucose (HG) to imitate the growth environment of cells under the DN condition. Levels of genes and proteins were tested by qRT-PCR and Western blot. Cell proliferation, apoptosis and inflammatory response were analyzed by using CCK-8, flow cytometry, and ELISA analysis, respectively. Oxidative stress and fibrosis were evaluated by detecting the activity of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), fibronectin (FN), and Collagen IV. The binding interaction between miR-151-3p and HMGA2 (High Mobility Group AT-Hook 2) or circNUP98 was confirmed using dual-luciferase reporter, pull-down and RIP assays. Exosomes were isolated by ultracentrifugation, and qualified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blot.

RESULTS

CircNUP98 expression was higher in the serum of DN patients and HG-stimulated HMCs. Functionally, circNUP98 knockdown alleviated HG-induced proliferation, fibrosis, inflammatory response and oxidative stress in HMCs. Mechanistically, circNUP98 directly sponged miR-151-3p, which targeted HMGA2. Rescue experiments showed that miR-151-3p reversed the inhibitory effects of circNUP98 knockdown on HG-induced HMC dysfunction. Moreover, miR-151-3p re-expression also led to an inhibition of above biological behaviors, which was attenuated by HMGA2 up-regulation. Besides that, CircNUP98 was found to be packaged into exosomes of DN, and exosomal circNUP98 possessed diagnostic value for DN patients.

CONCLUSION

CircNUP98 knockdown alleviates HG-induced proliferation, fibrosis inflammation and oxidative stress in HMCs by regulating miR-151-3p/HMGA2 axis, which may provide a potential approach for DN therapeutics.

Knockdown of circ_0003928 ameliorates high glucose-induced dysfunction of human tubular epithelial cells through the miR-506-3p/HDAC4 pathway in diabetic nephropathy

Background

Previous data have indicated the importance of circular RNA (circRNA) in the pathogenesis of diabetic nephropathy (DN). The study is designed to investigate the effects of circ_0003928 on oxidative stress and apoptosis of high glucose (HG)-treated human tubular epithelial cells (HK-2) and the underlying mechanism.

Methods

The DN cell model was established by inducing HK-2 cells using 30 mmol/L D-glucose. RNA expression of circ_0003928, miR-506-3p and histone deacetylase 4 (HDAC4) was detected by quantitative real-time polymerase chain reaction. Cell viability and proliferation were investigated by cell counting kit-8 and 5-Ethynyl-29-deoxyuridine (EdU) assays, respectively. Oxidative stress was evaluated by commercial kits. Caspase 3 activity and cell apoptotic rate were assessed by a caspase 3 activity assay and flow cytometry analysis, respectively. Protein expression was detected by Western blotting analysis. The interactions among circ_0003928, miR-506-3p and HDAC4 were identified by dual-luciferase reporter and RNA pull-down assays.

Results

Circ_0003928 and HDAC4 expression were significantly upregulated, while miR-506-3p was downregulated in the serum of DN patients and HG-induced HK-2 cells. HG treatment inhibited HK-2 cell proliferation, but induced oxidative stress and cell apoptosis; however, these effects were reversed after circ_0003928 depletion. Circ_0003928 acted as a miR-506-3p sponge, and HDAC4 was identified as a target gene of miR-506-3p. Moreover, the circ_0003928/miR-506-3p/HDAC4 axis regulated HG-induced HK-2 cell dysfunction.

Conclusion

Circ_0003928 acted as a sponge for miR-506-3p to regulate HG-induced oxidative stress and apoptosis of HK-2 cells through HDAC4, which suggested that circ_0003928 might be helpful in the therapy of DN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00679-y.

Circ_0000064 promotes high glucose-induced renal tubular epithelial cells injury to facilitate diabetic nephropathy progression through miR-532-3p/ROCK1 axis

BACKGROUND

Circular RNA (circRNA) has been shown to mediate diabetic nephropathy (DN) development by regulating renal tubular epithelial cells (RTECs) injury. However, the role and mechanism of circ_0000064 in high glucose (HG)-induced RTECs injury have not been fully elucidated.

METHODS

Human RTECs (HK-2) were exposed to HG to induce cell injury. Cell oxidative stress was assessed by detecting the levels of oxidative stress-markers. Moreover, cell proliferation and apoptosis were determined by CCK8 assay, EDU assay and flow cytometry. The protein levels of proliferation markers, apoptosis markers and Rho-associated coiled-coil-containing kinase 1 (ROCK1) were measured using western blot analysis. Furthermore, quantitative real-time PCR was performed to assess the expression of circ_0000064, microRNA (miR)-532-3p and ROCK1. The interaction between miR-532-3p and circ_0000064 or ROCK1 was confirmed by dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

Our results revealed that HG treatment could promote HK-2 cells oxidative stress, apoptosis, fibrosis, and inhibit proliferation. Circ_0000064 expression was increased in the serum of DN patients and HG-induced HK-2 cells, and silenced circ_0000064 could relieve HG-induced HK-2 cells injury. MiR-532-3p could be sponged by circ_0000064, and its overexpression also alleviated HG-induced HK-2 cells injury. Besides, the regulation of circ_0000064 knockdown on HG-induced HK-2 cells injury could be reversed by miR-532-3p inhibitor. Additionally, ROCK1 was a target of miR-532-3p, and its expression was inhibited by circ_0000064 knockdown. The inhibition effect of circ_0000064 knockdown on HG-induced HK-2 cells injury also could be reversed by overexpressing ROCK1.

CONCLUSION

In summary, circ_0000064 knockdown might alleviate HG-induced HK-2 cells injury via regulating the miR-532-3p/ROCK1 axis, which provided a new perspective for DN treatment.

Exosomal circTAOK1 contributes to diabetic kidney disease progression through regulating SMAD3 expression by sponging miR-520h

BACKGROUND

Diabetic nephropathy (DN) is a frequent diabetes complication with complex pathogenesis. Circular RNA (circRNA) circTAOK1 (also named circ_0003928) has been reported to be upregulated in high glucose (HG)-treated human umbilical vein endothelial cells. Also, exosomal circRNAs can exert significant roles in the pathology of various diseases. This study is designed to explore the role and mechanism of exosomal circTAOK1 on the glomerular mesangial cell (GMC) injury in DN.

METHODS

Exosomes were detected by a transmission electron microscope. The protein levels of CD9, CD63, proliferating cell nuclear antigen (PCNA), cyclinD1, α-SMA, fibronectin, E-cadherin, N-cadherin, and SMAD family member 3 (SMAD3) were examined by western blot assay. circTAOK1, microRNA-520h (miR-520h), and SMAD3 levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation and cell cycle progression were detected by cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays. The binding relationship between miR-520h and circTAOK1 or SMAD3 was predicted by Starbase and then verified by a dual-luciferase reporter and RNA immunoprecipitation (RIP), RNA pull-down assays.

RESULTS

CircTAOK1 expression was upregulated in the exosomes isolated from HG-treated glomerular epithelial cells (GEC). Moreover, GEC-circTAOK1-Exo could promote proliferation, fibrosis, and epithelial-mesenchymal transition (EMT) of glomerular mesangial cells (GMCs). Mechanically, circTAOK1 could regulate SMAD3 expression by sponging miR-520h, GEO-si-circTAOK1 Exo-induced miR-520h and repressed SMAD3 expression in GMC.

CONCLUSION

GEC-circTAOK1-Exo could boost proliferation, fibrosis, and EMT of GMC through targeting the miR-520h/SMAD3 axis, providing new insights into the pathogenesis of DN.

Circular RNAs in Diabetic Nephropathy: Updates and Perspectives

Circular RNAs (circRNAs) are widespread endogenous transcripts lacking 5′-caps and 3′-polyadenylation tails. Their closed-loop structure confers exonuclease resistance and extreme stability. CircRNAs play essential roles in various diseases, including diabetes. Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease and is one of the most common complications of diabetes. CircRNAs are key in DN and therefore important for understanding DN pathophysiology and developing new therapeutic strategies. In the present review, we briefly introduce the characteristics and functions of circRNAs and summarize recent discoveries on how circRNAs participate in DN. Based on these advances, we suggest future perspectives for studying circRNAs in DN to improve DN treatment and management.

Peripheral Blood circRNA Microarray Profiling Identities hsa_circ_0001831 and hsa_circ_0000867 as Two Novel circRNA Biomarkers for Early Type 2 Diabetic Nephropathy

PURPOSE

Type 2 diabetes mellitus (T2DM) increases the incidence of diabetic nephropathy (DN) and eventually progresses to end-stage renal disease. Circular RNAs (circRNAs) are a class of non-coding RNAs that are promising as diagnostic biomarkers and therapeutic targets for human diseases. The aim of this study was to analyze the differential expression of circRNAs (DECs) in peripheral blood from patients with early type 2 diabetic nephropathy (ET2DN), T2DM and controls, which will facilitate to discover some new biomarkers for ET2DN.

PATIENTS AND METHODS

Twenty ET2DN patients, 20 T2DM patients, and 20 normal controls were included in this study. Blood samples from 3 random subjects of age- and sex-matched patients in each group, respectively, were used to detect circRNA expression profiles by circRNA microarray, and the circRNA expression of remaining subjects was validated by real-time quantitative polymerase chain reaction (qRT-PCR). Further functional assessment was performed by bioinformatic tools.

RESULTS

There were 586 DECs in ET2DN vs T2DM group (249 circRNAs were upregulated and 337 circRNAs were downregulated); 176 circRNAs were upregulated and 101 circRNAs were downregulated in T2DM vs control group; 57 circRNAs were upregulated and 5 circRNAs were downregulated in ET2DN vs control group. The functional and pathway enrichment of DECs were analyzed by GO and KEGG. qRT-PCR results revealed that hsa_circ_0001831 and hsa_circ_0000867 were significantly upregulated in ET2DN group compared to both of T2DM and control group. The ROC curve demonstrated that hsa_circ_0001831 and hsa_circ_0000867 have high sensitivity and specificity associated with ET2DN.

CONCLUSION

Our study showed the expression profiles of circRNAs in ET2DN patients and demonstrated that hsa_circ_0001831 and hsa_circ_0000867 can be used as novel diagnostic biomarkers for ET2DN.

Circular RNAs in diabetes mellitus and its complications

Diabetes mellitus (DM) is an endocrine disorder characterized by a relative or absolute lack of insulin due to the dysfunction or destruction of β-cells. DM is one of the fastest growing challenges to global health in the 21^st century and places a tremendous burden on affected individuals and their families and countries. Although insulin and antidiabetic drugs have been used to treat DM, a radical cure for the disease is unavailable. The pathogenesis of DM remains unclear. Emerging roles of circular RNAs (circRNAs) in DM have become a subject of global research. CircRNAs have been verified to participate in the onset and progression of DM, implying their potential roles as novel biomarkers and treatment tools. In the present review, we briefly introduce the characteristics of circRNAs. Next, we focus on specific roles of circRNAs in type 1 diabetes mellitus, type 2 diabetes mellitus, gestational diabetes mellitus and diabetes-associated complications.

Circular RNA_0037128 aggravates high glucose-induced damage in HK-2 cells via regulation of microRNA-497-5p/nuclear factor of activated T cells 5 axis

Circular RNAs (CircRNAs) were reported to play vital roles in the progression of DN. Herein, the action of circular RNA_0037128 (circ_0037128) was investigated in DN. The level of circ_0037128, microRNA-497-5p (miR-497-5p) and nuclear factor of activated T cells 5 (NFAT5) was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The feature of circ_0037128 was tested by RNase R and Actinomycin D treatment assays. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2ʹ-deoxyuridine (EdU) staining assays were conducted to evaluate the proliferation ability. The relative protein expression was determined via Western blot analysis. Levels of the inflammatory cytokines, like tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), were assessed by enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) and superoxide dismutase (SOD) activity were determined by the matched kits. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were conducted for evaluating the correlation between miR-497-5p and circ_0037128 or NFAT5. Circ_0037128 and NFAT5 were enhanced, while miR-497-5p was weakened in kidney tissues of DN patients and high glucose (HG)-cultured HK-2 cells. Circ_0037128 inhibition bated HG-caused inhibition effect on cell proliferation and promotion effects on oxidative stress, inflammation and fibrosis in HK-2 cells. Moreover, circ_0037128 knockdown alleviated HG-caused cell damage via regulating miR-497-5p. In addition, NFAT5 overexpression could reverse the influence of miR-497-5p on HG-induced injury in HK-2 cells. Mechanically, circ_0037128 sponged miR-497-5p to modulate NFAT5. Circ_0037128 downregulation could mitigate HG-stimulated cell damage via regulating the miR-497-5p/NFAT5 axis in HK-2 cells in vitro, providing a possible therapy target for DN.

Circular RNAs; powerful microRNA sponges to overcome diabetic nephropathy

Diabetic nephropathy (DN), also known as diabetic kidney disease (DKD), is a drastic renal complication of type 1 and type 2 diabetes mellitus (DM). Poorly controlled DM over the years, may disrupt kidneys' blood vessels, leading to the hypertension (HTN) and DN onset. During DN, kidneys' waste filtering ability becomes disturbed. Being on a healthy lifestyle and controlling both DM and HTN are now the best proceedings to prevent or at least delay DN occurrence. Unfortunately, about one-fourth of diabetic individuals eventually experience the corresponding renal failure, and thus it is critical to discover effective diagnostic biomarkers and therapeutic strategies to combat DN. In the past few years, circular RNAs (circRNAs), as covalently closed endogenous non-coding RNAs (ncRNAs), are believed to affect DN pathogenesis in a positive manner. CircRNAs are able to impact different cellular processes and signaling pathways by targeting biological molecules or various molecular mechanisms. Still, as a key regulatory axis, circRNAs can select miRNAs as their molecular targets, in which they are considered as miRNA sponges. In this way, circRNA-induced suppression of particular miRNAs may prevent from DN progression or promotes the DN elimination. Since the expression of circRNAs has also been reported to be increased in DN-associated cells and tissues, they can be employed as either diagnostic biomarkers or therapeutic targets.

Circular RNAs as Novel Diagnostic Biomarkers and Therapeutic Targets in Kidney Disease

Circular RNAs (circRNAs) are a novel type of non-coding RNAs that have aroused growing attention in this decade. They are widely expressed in eukaryotes and generally have high stability owing to their special closed-loop structure. Many circRNAs are abundant, evolutionarily conserved, and exhibit cell-type-specific and tissue-specific expression patterns. Mounting evidence suggests that circRNAs have regulatory potency for gene expression by acting as microRNA sponges, interacting with proteins, regulating transcription, or directly undergoing translation. Dysregulated expression of circRNAs were found in many pathological conditions and contribute to the pathogenesis and progression of various disorders, including renal diseases. Recent studies have revealed that circRNAs may serve as novel reliable biomarkers for the diagnosis and prognosis prediction of multiple kidney diseases, such as renal cell carcinoma (RCC), acute kidney injury (AKI), diabetic kidney disease (DKD), and other glomerular diseases. Furthermore, circRNAs expressed by intrinsic kidney cells are shown to play a substantial role in kidney injury, mostly reported in DKD and RCC. Herein, we review the biogenesis and biological functions of circRNAs, and summarize their roles as promising biomarkers and therapeutic targets in common kidney diseases.

Epigenetics and Inflammation in Diabetic Nephropathy

Diabetic nephropathy (DN) leads to high morbidity and disability. Inflammation plays a critical role in the pathogenesis of DN, which involves renal cells and immune cells, the microenvironment, as well as extrinsic factors, such as hyperglycemia, chemokines, cytokines, and growth factors. Epigenetic modifications usually regulate gene expression via DNA methylation, histone modification, and non-coding RNAs without altering the DNA sequence. During the past years, numerous studies have been published to reveal the mechanisms of epigenetic modifications that regulate inflammation in DN. This review aimed to summarize the latest evidence on the interplay of epigenetics and inflammation in DN, and highlight the potential targets for treatment and diagnosis of DN.

Circ_0093887 upregulates CCND2 and SUCNR1 to inhibit the ox-LDL-induced endothelial dysfunction in atherosclerosis by functioning as a miR-876-3p sponge

Circular RNAs (circRNAs) are widely expressed in mammals and act as regulatory targets in the atherogenesis. The objective of this study was to research the biological role and molecular mechanism of circ_0093887 in oxidized low-density lipoprotein (ox-LDL)-induced atherosclerosis (AS) of human aortic endothelial cells (HAECs). Cell viability detection was performed by CCK-8 assay. Inflammatory molecules were examined using ELISA. Flow cytometry was used to measure cell-cycle progression and cell apoptotic rate. Caspase 3 activity was determined using caspase 3 activity assay. The expression levels of circ_0093887, miR-876-3p, CCND2 and SUCNR1 were assayed by quantitative real-time polymerase chain reaction (qRT-PCR). Dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays were used for the target analysis. EdU assay, wound healing assay/transwell assay and tube formation assay were, respectively, used to assess the effects of circ_0093887/miR-876-3p axis on cell proliferation, migration and tube formation. Oxidized low-density lipoprotein inhibited cell viability and cell-cycle progression but induced the inflammatory response and cell apoptosis. Circ_0093887 was downregulated and miR-876-3p was upregulated in AS patients and ox-LDL-treated HAECs. Functionally, the overexpression of circ_0093887 abrogated the cell injury of HAEC exposed to ox-LDL. For the functional mechanism, we found that circ_0093887 was a sponge for miR-876-3p and miR-876 targeted CCND2 or SUCNR1. The reverted experiment indicated that the function of circ_0093887 was achieved by sponging miR-876-3p. Meanwhile, miR-876-3p inhibitor relieved the inhibitory regulation of circ_0093887 knockdown in cell proliferation, migration and tube formation. Downregulation of miR-876-3p also alleviated the ox-LDL-induced cell injury by upregulating the expression of CCND2 or SUCNR1. Furthermore, circ_0093887 was validated to regulate the levels of CCND2 and SUCNR1 via the sponge effect on miR-876-3p. The protective effects of circ_0093887 on HAECs from ox-LDL were also ​alleviated by repressing the CCND2 and SUCNR1 levels. These findings suggested that circ_0093887 protected HAEC against the ox-LDL-induced inflammatory and apoptotic damages by targeting the miR-876-3p/CCND2 or miR-876/SUCNRA axis. Circ_0093887 could act as a potential therapeutic biomarker for AS patients.

Mechanism of miR-365 in regulating BDNF-TrkB signal axis of HFD/STZ induced diabetic nephropathy fibrosis and renal function

PURPOSE

Diabetic nephropathy (DN) is one of the most serious complications of diabetes that leads to decline of renal function. Although numerous studies have revealed that microRNAs (miRNAs) play essential roles in the progression of DN, whether miR-365 is involved remains elusive.

METHODS

The successful construction of DN model was confirmed by ELSIA, hematoxylin-eosin (HE) and Masson staining assay. The expression of miR-365 was detected through RT-qPCR. The levels of BDNF, p-TrkB, α-smooth muscle actin (SMA), collagen IV (Col.IV), transforming growth factor-β1 (TGF-β1), tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) were evaluated by western blot, IF or ELISA assays. Luciferase reporter assay was used to detect the interaction between miR-365 and BDNF.

RESULTS

The DN mice model was induced by streptozotocin (STZ). Then miR-365 expression was found to upregulate in tissues of DN rat. Furthermore, elevated expression of miR-365 was found in high glucose (HG)-treated HK-2 cells. Silencing of miR-365 suppressed the accumulation of ECM components and secretion of inflammatory cytokines in HK-2 cells. In addition, it was demonstrated that miR-365 could target BDNF. The protein levels of BDNF and p-TrkB were negatively regulated by miR-365 in HK-2 cells. Moreover, inhibition of miR-365 suppressed the levels of SMA, Col.IV, TGF-β1, TNF-α, and IL-6, indicating the renal fibrosis was inhibited by miR-365 knockdown.

CONCLUSION

MiR-365 could regulate BDNF-TrkB signal axis in STZ induced DN fibrosis and renal function. The results of the current study might provide a promising biomarker for the treatment of DN in the future.