Circ_LARP4 regulates high glucose-induced cell proliferation, apoptosis, and fibrosis in mouse mesangial cells

CircLARP1B promotes pyroptosis of high glucose-induced renal mesangial cells by regulating the miR-578/TLR4 axis

BACKGROUND

Diabetic nephropathy (DN) is a main cause of end-stage renal disease with high mortality. Circular RNAs (circRNAs) are associated with the pathogenesis of DN. This study aimed to explore the role of circLARP1B in DN.

METHODS

The levels of circLARP1B, miR-578, TLR4 in DN and high glucose (HG)-treated cells using quantitative real-time PCR. Their relationship was analyzed using dual-luciferase reporter assay. The biological behaviors were assessed by MTT assay, EDU assay, flow cytometry, ELISA, and western blot.

RESULTS

The results indicated that circLARP1B and TLR4 were highly expressed, and miR-578 was low expressed in patients with DN and HG-induced cells. Knockdown of circLARP1B promoted the proliferation and cell cycle, and inhibited pyroptosis and inflammation of HG-induced cells. CircLARP1B is a sponge of miR-578, which targets TLR4. Rescue experiments showed that inhibition of miR-578 reversed the effects of circLARP1B knockdown, while TLR4 reversed the effects of miR-578.

CONCLUSION

CircLARP1B/miR-578/TLR4 axis suppressed the proliferation, blocked cell cycle at the G0-G1 phase, promoted pyroptosis, and inflammatory factor release of renal mesangial cells induced by HG. The findings suggested that circLARP1B may be a target for the treatment of DN.

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.

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.

Hsa_circ_0008500 inhibits apoptosis of adipose-derived stem cells under high glucose through hsa-miR-1273h-5p/ELK1 axis

Preliminary researches have confirmed that the number of apoptosis of adipose tissue-derived stem cells (ADSCs) in patients with diabetes is significantly increased, leading to a difficult healing wound. Increasing researches revealed that circular RNAs (circRNAs) can control apoptosis. However, it is still unclear whether and how circRNAs are critical for regulating ADSCs apoptosis. In this study, we utilized in vitro model in which ADSCs were cultivated with normal glucose (NG) (5.5 mM) or high glucose (HG) (25 mM) medium, respectively, and found that more apoptotic ADSCs were observed in HG medium comparing to ADSCs in NG medium. Furthermore, we found that hsa_circ_0008500 attenuated HG-mediated ADSCs apoptosis. In addition, Hsa_circ_0008500 could directly interact with hsa-miR-1273h-5p, acting as a miRNA sponge, which subsequently suppressed Ets-like protein-1(ELK1) expression, the downstream target of hsa-miR-1273h-5p. Thus, these results indicated that targeting the hsa_circ_0008500/hsa-miR-1273h-5p/ELK1 signaling pathway in ADSCs may be a potential target for repairing diabetic wounds.

Circular RNAs in diabetes and its complications: Current knowledge and future prospects

A novel class of non-coding RNA transcripts called circular RNAs (circRNAs) have been the subject of significant recent studies. Accumulating evidence points that circRNAs play an important role in the cellular processes, inflammatory expression, and immune responses through sponging miRNA, binding, or translating in proteins. Studies have found that circRNAs are involved in the physiologic and pathologic processes of diabetes. There has been an increased focus on the relevance of between abnormal circRNA expression and the development and progression of various types of diabetes and diabetes-related diseases. These circRNAs not only serve as promising diagnostic and prognostic molecular biomarkers, but also have important biological roles in islet cells, diabetes, and its complications. In addition, many circRNA signaling pathways have been found to regulate the occurrence and development of diabetes. Here we comprehensively review and discuss recent advances in our understanding of the physiologic function and regulatory mechanisms of circRNAs on pancreatic islet cells, different subtypes in diabetes, and diabetic complications.

TLR9 regulates NLRP3 inflammasome activation via the NF-kB signaling pathway in diabetic nephropathy

BACKGROUND

Toll-like receptors (TLRs) are critical sensors for the conservation of bacterial molecules and play a key role in host defense against pathogens. The effect of TLRs on the maintenance of diabetic nephropathy (DN) and resistance to infection has been investigated; however, the detailed effects of TLR9 on DN development remain elusive.

METHODS

We performed quantitative reverse transcription-polymerase chain reaction and western blotting to detect TLR9 expression levels in the kidneys of experimental mice (db/db) and high-glucose-treated mouse mesangial cell strains (MCs).

RESULTS

TLR9 expression was found to be remarkably upregulated in the kidneys of experimental mice (db/db) and MCs cultivated under hyperglycemic conditions. Moreover, knockdown of TLR9 could restrain NF-kB viability and downregulate the NLRP3 inflammasome in high glucose-treated MCs. TLR9 inhibition also alleviated inflammation and apoptosis, which was reversed by the addition of the NF-κB activator, betulinic acid. Furthermore, depleted TLR9 levels restrained NF-κB viability and NLRP3 expression and reduced kidney inflammation, microalbuminuria discharge, blood sugar level, and glomerular damage in experimental mice (db/db) kidneys. Conclusions These findings offer novel insights into the regulation of TLR9 via the nuclear factor-kB/NOD-, LRR-, and pyrin domain-containing protein 3 inflammasome inflammation pathways in DN progression.

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.

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.

Circ-FBXW12 aggravates the development of diabetic nephropathy by binding to miR-31-5p to induce LIN28B

BACKGROUND

The involvement of circular RNAs (circRNAs) in diabetic nephropathy (DN) has been gradually identified. In this study, we aimed to explore the functions of circRNA F-box/WD repeat-containing protein 12 (circ-FBXW12) in DN development.

METHODS

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay was performed for the levels of circ-FBXW12, FBXW12 mRNA, microRNA-31-5p (miR-31-5p) and Lin-28 homolog B (LIN28B) mRNA. RNase R assay was used to analyze the stability of circ-FBXW12. Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis and 5-ethynyl-2'- deoxyuridine (EdU) assay were employed to evaluate cell viability, cell cycle and proliferation, respectively. Enzyme linked immunosorbent assay (ELISA) was done to measure the concentrations of inflammatory cytokines. Western blot assay was conducted for protein levels. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were examined with commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the relationships among circ-FBXW12, miR-31-5p and LIN28B.

RESULTS

Circ-FBXW12 level was increased in DN patients' serums and high glucose (HG)-induced human mesangial cells (HMCs). Circ-FBXW12 knockdown suppressed cell proliferation, arrested cell cycle, reduced extracellular matrix (ECM) production and oxidative stress in HG-induced HMCs. Circ-FBXW12 was identified as the sponge for miR-31-5p, which then directly targeted LIN28B. MiR-31-5p inhibition reversed circ-FBXW12 knockdown-mediated effects on cell proliferation, cell cycle process, ECM production and oxidative in HG-triggered HMCs. Moreover, miR-31-5p overexpression showed similar results with circ-FBXW12 knockdown in HG-stimulated HMC progression, while LIN28B elevation reversed the effects.

CONCLUSION

Circ-FBXW12 knockdown suppressed HG-induced HMC growth, inflammation, ECM accumulation and oxidative stress by regulating miR-31-5p/LIN28B axis.

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.

Overexpression of mm9_circ_013935 alleviates renal inflammation and fibrosis in diabetic nephropathy via the miR-153-3p/NFIC axis

BACKGROUND

Circ-RBM4 (mm9_circ_013935) has been revealed to be low-expressed in the renal tissues of diabetic nephropathy (DN) mice while its underlying regulatory mechanism remains unexplored.

METHODS

The high glucose (HG)-treated mouse podocytes were used to establish the DN cell models. A CCK-8 assay was used to examine the viability of mouse podocytes. The expression of proteins related to fibrosis (Collagen I, Collagen III, fibronectin) was detected using western blot. The concentration of inflammation cytokines (TNF-α, IL-1β, IL-8) in mouse podocytes was assessed by ELISA. The interaction between genes was explored by luciferase reporter assays.

RESULTS

HG treatement decreased the viability and elevated the expression of fibrosis and inflammation factors in mouse podocytes. Circ-RBM4 expression was downregulated in HG-treated mouse podocytes. Circ-RBM4 overexpression reversed HG-induced increase in levels of proteins related to fibrosis and the concentration of inflammation factors. MiR-153-3p was revealed to bind with circ-RBM4 and directly targeted nuclear factor I/C (NFIC) in mouse podocytes. Rescue assays indicated that circ-RBM4 attenuated HG-induced fibrosis and inflammation response in mouse podocytes by inhibiting miR-153-3p expression or upregulating NFIC expression.

CONCLUSION

Circ-RBM4 alleviated the renal inflamation and renal fibrosis in DN by targeting the miR-153-3p/NFIC axis.