MicroRNA-451 regulates p38 MAPK signaling by targeting of Ywhaz and suppresses the mesangial hypertrophy in early diabetic nephropathy

A Systematic Review and Meta-Analysis of microRNA Profiling Studies in Chronic Kidney Diseases

Chronic kidney disease (CKD) represents an increasing health burden. Evidence suggests the importance of miRNA in diagnosing CKD, yet the reports are inconsistent. This study aimed to determine novel miRNA biomarkers and potential therapeutic targets from hypothesis-free miRNA profiling studies in human and murine CKDs. Comprehensive literature searches were conducted on five databases. Subgroup analyses of kidney diseases, sample types, disease stages, and species were conducted. A total of 38 human and 12 murine eligible studies were analyzed using Robust Rank Aggregation (RRA) and vote-counting analyses. Gene set enrichment analyses of miRNA signatures in each kidney disease were conducted using DIANA-miRPath v4.0 and MIENTURNET. As a result, top target genes, Gene Ontology terms, the interaction network between miRNA and target genes, and molecular pathways in each kidney disease were identified. According to vote-counting analysis, 145 miRNAs were dysregulated in human kidney diseases, and 32 were dysregulated in murine CKD models. By RRA, miR-26a-5p was significantly reduced in the kidney tissue of Lupus nephritis (LN), while miR-107 was decreased in LN patients' blood samples. In both species, epithelial-mesenchymal transition, Notch, mTOR signaling, apoptosis, G2/M checkpoint, and hypoxia were the most enriched pathways. These miRNA signatures and their target genes must be validated in large patient cohort studies.

Metformin inhibits high glucose-induced apoptosis of renal podocyte through regulating miR-34a/SIRT1 axis

BACKGROUND

Previous studies have reported SIRT1 was inversely modulated by miR-34a, However, mechanism of metformin (MFN)'s renal podocyte protection under high glucose (HG) conditions and the connection between miR-34a and SIRT1 expression in diabetic nephropathy (DN) remain unclear.

METHOD

We aimed to further elucidate the role of miR-34a in HG-treated podocytes in DN. A conditionally immortalized human podocyte cell line was cultivated in d-glucose (30 mM).

RESULTS

Microarray and RT-qPCR revealed that miR-34a was downregulated in HG-treated podocytes. Additionally, miR-34a levels increased in MFN-treated HG-induced podocytes. CCK-8 assay, colony formation assay, flow cytometry, and Western blot detection showed that HG treatment reduced cell viability and promoted via HG treatment, and MFN treatment reversed this phenotypic change. MiR-34a upregulation caused restored cell viability and suppressed cell apoptosis in HG-treated podocytes, and miR-34a downregulation led to damaged cell survival and induced apoptosis in MFN-administered and HG-treated podocytes. The dual luciferase reporter assay showed that SIRT1 3'-UTR was a direct miR-34a target. Further studies demonstrated an elevation in SIRT1 levels in HG-exposed podocytes, whereas MFN treatment decreased SIRT1 levels. In addition, miR-34a upregulation led to reduced SIRT1 expression, whereas miR-34a inhibition increased SIRT1 levels in cells. MFN-induced miR-34a suppresses podocyte apoptosis under HG conditions by acting on SIRT1.

CONCLUSION

This study proposes a promising approach to interpret the mechanisms of action of the MFN-miR-34a axis involved in DN.

Long non‑coding RNA L13Rik promotes high glucose-induced mesangial cell hypertrophy and matrix protein expression by regulating miR-2861/CDKN1B axis

Background

Diabetic nephropathy (DN) is a frequent microvascular complication of diabetes. Glomerular mesangial cell (MC) hypertrophy occurs at the initial phase of DN and plays a critical role in the pathogenesis of DN. Given the role of long non coding RNA (lncRNA) in regulating MC hypertrophy and extracellular matrix (ECM) accumulation, our aim was to identify functional lncRNAs during MC hypertrophy.

Methods

Here, an lncRNA, C920021L13Rik (L13Rik for short), was identified to be up-regulated in DN progression. The expression of L13Rik in DN patients and diabetic mice was assessed using quantitative real-time PCR (qRT-PCR), and the function of L13Rik in regulating HG-induced MC hypertrophy and ECM accumulation was assessed through flow cytometry and western blotting analysis.

Results

The L13Rik levels were significantly increased while the miR-2861 levels were decreased in the peripheral blood of DN patients, the renal tissues of diabetic mice, and HG-treated MCs. Functionally, both L13Rik depletion and miR-2861 overexpression effectively reduced HG-induced cell hypertrophy and ECM accumulation. Mechanistically, L13Rik functioned as a competing endogenous RNA (ceRNA) to sponge miR-2861, resulting in the de-repression of cyclin-dependent kinase inhibitor 1B (CDKN1B), a gene known to regulate cell cycle and MC hypertrophy.

Conclusions

Collectively, the current results demonstrate that up-regulated L13Rik is correlated with DN and may be a hopeful therapeutic target for DN.

Cell-Based Therapies for Glaucoma

Glaucomatous optic neuropathy (GON) is the major cause of irreversible visual loss worldwide and can result from a range of disease etiologies. The defining features of GON are retinal ganglion cell (RGC) degeneration and characteristic cupping of the optic nerve head (ONH) due to tissue remodeling, while intraocular pressure remains the only modifiable GON risk factor currently targeted by approved clinical treatment strategies. Efforts to understand the mechanisms that allow species such as the zebrafish to regenerate their retinal cells have greatly increased our understanding of regenerative signaling pathways. However, proper integration within the retina and projection to the brain by the newly regenerated neuronal cells remain major hurdles. Meanwhile, a range of methods for in vitro differentiation have been developed to derive retinal cells from a variety of cell sources, including embryonic and induced pluripotent stem cells. More recently, there has been growing interest in the implantation of glial cells as well as cell-derived products, including neurotrophins, microRNA, and extracellular vesicles, to provide functional support to vulnerable structures such as RGC axons and the ONH. These approaches offer the advantage of not relying upon the replacement of degenerated cells and potentially targeting earlier stages of disease pathogenesis. In order to translate these techniques into clinical practice, appropriate cell sourcing, robust differentiation protocols, and accurate implantation methods are crucial to the success of cell-based therapy in glaucoma. Translational Relevance: Cell-based therapies for glaucoma currently under active development include the induction of endogenous regeneration, implantation of exogenously derived retinal cells, and utilization of cell-derived products to provide functional support.

The Role of MicroRNA in the Pathogenesis of Diabetic Nephropathy

Diabetic nephropathy is one of the most common and severe complications of diabetes mellitus, affecting one in every five patients suffering from diabetes. Despite extensive research, the exact pathogenesis of diabetic nephropathy is still unclear. Several factors and pathways are known to be involved in the development of the disease, such as reactive oxygen species or the activation of the renin–angiotensin–aldosterone system. The expression of those proteins might be extensively regulated by microRNA. Recent research suggests that in diabetic nephropathy patients, the profile of miRNA is significantly changed. In this review, we focus on the actions of miRNA in various pathways involved in the pathogenesis of diabetic nephropathy and the clinical usage of miRNAs as biomarkers and therapeutic targets.

miRNA Signature of Urine Extracellular Vesicles Shows the Involvement of Inflammatory and Apoptotic Processes in Diabetic Chronic Kidney Disease

BACKGROUND

The aim of this study was to investigate the role of urine-derived extracellular vesicles (uEVs) in diabetic kidney disease (DKD) in patients diagnosed with type 2 diabetes mellitus (T2DM).

METHODS

UEVs were characterized by size distribution and microRNA content by next-generation small RNA sequencing and quantitative reverse transcription PCR.

RESULTS

A subset of sixteen miRNAs enriched in T2DM patients with DKD, including hsa-miR-514a-5p, hsa-miR‑451a, hsa-miR-126-3p, hsa-miR-214, or hsa-miR‑503 was identified. Eight miRNAs as hsa-miR-21-3p, hsa-miR-4792, hsa-miR‑375, hsa-miR-1268a, hsa-miR-501-5p, or hsa-miR-582 were downregulated. Prediction of potential target genes and pathway enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) confirmed possible functions related to cellular processes such as apoptosis, inflammation, and tissue remodeling, that promote diabetic complications, such as DKD. Among them, hsa-miR-375, hsa-miR-503, and hsa-miR-451a make important contribution. Additionally, downregulated hsa-miR-582-5p has not been reported so far in any diabetes-related pathways.

CONCLUSIONS

This study revealed the most significant miRNAs in uEVs of patients with T2DM. However, as this is a bioinformatic prediction that we performed based on the putative targets of the identified miRNAs. Thus, further in vitro functional studies are needed to confirm our findings. Knowing the fact that EVs are crucial in transferring miRNAs, there is a great need toto discover their involvement in the pathomechanism of T2DM-related kidney disease.

Molecular profiling of urinary extracellular vesicles in chronic kidney disease and renal fibrosis

Chronic kidney disease (CKD) is a long-term kidney damage caused by gradual loss of essential kidney functions. A global health issue, CKD affects up to 16% of the population worldwide. Symptoms are often not apparent in the early stages, and if left untreated, CKD can progress to end-stage kidney disease (ESKD), also known as kidney failure, when the only possible treatments are dialysis and kidney transplantation. The end point of nearly all forms of CKD is kidney fibrosis, a process of unsuccessful wound-healing of kidney tissue. Detection of kidney fibrosis, therefore, often means detection of CKD. Renal biopsy remains the best test for renal scarring, despite being intrinsically limited by its invasiveness and sampling bias. Urine is a desirable source of fibrosis biomarkers as it can be easily obtained in a non-invasive way and in large volumes. Besides, urine contains biomolecules filtered through the glomeruli, mirroring the pathological state. There is, however, a problem of highly abundant urinary proteins that can mask rare disease biomarkers. Urinary extracellular vesicles (uEVs), which originate from renal cells and carry proteins, nucleic acids, and lipids, are an attractive source of potential rare CKD biomarkers. Their cargo consists of low-abundant proteins but highly concentrated in a nanosize-volume, as well as molecules too large to be filtered from plasma. Combining molecular profiling data (protein and miRNAs) of uEVs, isolated from patients affected by various forms of CKD, this review considers the possible diagnostic and prognostic value of uEVs biomarkers and their potential application in the translation of new experimental antifibrotic therapeutics.

DICAM in the Extracellular Vesicles from Astrocytes Attenuates Microglia Activation and Neuroinflammation

Cross-talk between astrocytes and microglia plays an important role in neuroinflammation and central sensitization, but the manner in which glial cells interact remains less well-understood. Herein, we investigated the role of dual immunoglobulin domain-containing cell adhesion molecules (DICAM) in the glial cell interaction during neuroinflammation. DICAM knockout (KO) mice revealed enhanced nociceptive behaviors and glial cell activation of the tibia fracture with a cast immobilization model of complex regional pain syndrome (CRPS). DICAM was selectively secreted in reactive astrocytes, mainly via extracellular vesicles (EVs), and contributed to the regulation of neuroinflammation through the M2 polarization of microglia, which is dependent on the suppression of p38 MAPK signaling. In conclusion, DICAM secreted from reactive astrocytes through EVs was involved in the suppression of microglia activation and subsequent attenuation of neuroinflammation during central sensitization.

Variable expression of eighteen common housekeeping genes in human non-cancerous kidney biopsies

Housekeeping, or reference genes (RGs) are, by definition, loci with stable expression profiles that are widely used as internal controls to normalize mRNA levels. However, due to specific events, such as pathological changes, or technical procedures, their expression might be altered, failing to fulfil critical normalization pre-requisites. To identify RG genes suitable as internal controls in human non-cancerous kidney tissue, we selected 18 RG candidates based on previous data and screen them in 30 expression datasets (>800 patients), including our own, publicly available or provided by independent groups. Datasets included specimens from patients with hypertensive and diabetic nephropathy, Fabry disease, focal segmental glomerulosclerosis, IgA nephropathy, membranous nephropathy, and minimal change disease. We examined both microdissected and whole section-based datasets. Expression variability of 4 candidate genes (YWHAZ, SLC4A1AP, RPS13 and ACTB) was further examined by qPCR in biopsies from patients with hypertensive nephropathy (n = 11) and healthy controls (n = 5). Only YWHAZ gene expression remained stable in all datasets whereas SLC4A1AP was stable in all but one Fabry dataset. All other RGs were differentially expressed in at least 2 datasets, and in 4.5 datasets on average. No differences in YWHAZ, SLC4A1AP, RPS13 and ACTB gene expression between hypertensive and control biopsies were detected by qPCR. Although RGs suitable to all techniques and tissues are unlikely to exist, our data suggest that in non-cancerous kidney biopsies expression of YWHAZ and SLC4AIAP genes is stable and suitable for normalization purposes.

Systems biology and machine learning approaches identify drug targets in diabetic nephropathy

Diabetic nephropathy (DN), the leading cause of end-stage renal disease, has become a massive global health burden. Despite considerable efforts, the underlying mechanisms have not yet been comprehensively understood. In this study, a systematic approach was utilized to identify the microRNA signature in DN and to introduce novel drug targets (DTs) in DN. Using microarray profiling followed by qPCR confirmation, 13 and 6 differentially expressed (DE) microRNAs were identified in the kidney cortex and medulla, respectively. The microRNA-target interaction networks for each anatomical compartment were constructed and central nodes were identified. Moreover, enrichment analysis was performed to identify key signaling pathways. To develop a strategy for DT prediction, the human proteome was annotated with 65 biochemical characteristics and 23 network topology parameters. Furthermore, all proteins targeted by at least one FDA-approved drug were identified. Next, mGMDH-AFS, a high-performance machine learning algorithm capable of tolerating massive imbalanced size of the classes, was developed to classify DT and non-DT proteins. The sensitivity, specificity, accuracy, and precision of the proposed method were 90%, 86%, 88%, and 89%, respectively. Moreover, it significantly outperformed the state-of-the-art (P-value ≤ 0.05) and showed very good diagnostic accuracy and high agreement between predicted and observed class labels. The cortex and medulla networks were then analyzed with this validated machine to identify potential DTs. Among the high-rank DT candidates are Egfr, Prkce, clic5, Kit, and Agtr1a which is a current well-known target in DN. In conclusion, a combination of experimental and computational approaches was exploited to provide a holistic insight into the disorder for introducing novel therapeutic targets.

Trigonelline induces autophagy to protect mesangial cells in response to high glucose via activating the miR-5189-5p-AMPK pathway

BACKGROUND

Diabetic nephropathy (DN) is a primary cause of end-stage renal disease. Increasing evidence indicates that microRNAs (miRNAs) are involved in DN pathogenesis. Trigonelline (TRL) has been shown to lower blood sugar and cholesterol levels, promote nerve regeneration, and exert anti-cancer and sedative properties.

METHOD

The effect of TRL on human mesangial cell (HMC) growth was assessed using the MTT assay. Differentially expressed miRNAs were validated using real-time quantitative polymerase chain reaction (real-time PCR). Bioinformatics, cell transfection, and Western blot analyses were utilized to confirm the binding of miR-5189-5p to HIF1AN. The effects of miR-5189-5 expression on cell proliferation were also assessed. Western blot analysis was used to determine the activation of multiple signaling molecules including phosphorylated-(p)-AMPK, SIRT1, LC3B, p62, and Beclin-1 in the autophagy pathway.

RESULTS

TRL improved proliferation, increased the expression of miR-5189-5p, reduced HIF1AN, and restored the inhibition of autophagy in HMCs induced by high glucose. MiR-5189-5p mimics inhibited HIF1AN expression, and the miR-5189-5p inhibitor increased HIF1AN expression. MiR-5189-5p mimics significantly improved the proliferation of HMCs induced by high glucose, reduced the relative protein expression of p-AMPK, SIRT1, LC3B, and Beclin-1, and significantly increased the relative protein expression of p62.

CONCLUSION

We showed that TRL up-regulated miR-5189-5p expression, activated the AMPK pathway, and activated autophagy in HMCs. Our study demonstrates that TRL could be a new treatment strategy to protect mesangial cells in response to high glucose.

Plasma miR-193a-3p can be a potential biomarker for the diagnosis of diabetic nephropathy

BACKGROUND

Diabetic nephropathy is one of the most common microvascular complications in patients with diabetes. MicroRNA (miRNA, miR) is closely related to the formation, development and pathophysiology of diabetic nephropathy. We aimed to investigate whether miR-193a-3p could be used as a potential biomarker for the diagnosis of diabetic nephropathy.

METHODS

Plasma samples were collected from all the participants. TaqMan Low Density Array analysis was employed to obtain the miRNA profiles of plasma samples, and qRT-PCR was used to confirm the result. Receiver operating characteristic curves were employed to evaluate the specificity and sensitivity of miR-193a-3p for predicting diabetic nephropathy.

RESULTS

The expression of miR-193a-3p and miR-320c was elevated and miR-27a-3p was decreased in diabetic nephropathy patients compared to patients with type 2 diabetes and healthy controls. We found that, in diabetic nephropathy patients, the elevated miR-193a-3p expression had a negative correlation with the level of evaluate glomerular filtration rate, while a positive correlation with the level of proteinuria. We further demonstrated that miR-193a-3p could be employed to distinguish patients with diabetic nephropathy. The Kaplan-Meier analysis showed that the high expression of miR-193a-3p significantly shortened the dialysis-free survival of diabetic nephropathy patients.

CONCLUSION

In conclusion, miR-193a-3p is involved in diabetic nephropathy pathogenesis and may serve as a potentially novel diagnostic biomarker for diabetic nephropathy.

MicroRNAs in diabetic nephropathy: From molecular mechanisms to new therapeutic targets of treatment

Despite considerable investigation in diabetic nephropathy (DN) pathogenesis and possible treatments, current therapies still do not provide competent prevention from disease progression to end-stage renal disease (ESRD) in most patients. Therefore, investigating exact molecular mechanisms and important mediators underlying DN may help design better therapeutic approaches for proper treatment. MicroRNAs (MiRNAs) are a class of small non-coding RNAs that play a crucial role in post-transcriptional regulation of many gene expression within the cells and present an excellent opportunity for new therapeutic approaches because their profile is often changed during many diseases, including DN. This review discusses the most important signaling pathways involved in DN and changes in miRNAs profile in each signaling pathway. We also suggest possible approaches for miRNA derived interventions for designing better treatment of DN.

Systemic inhibition of miR-451 increases fibrotic signaling and diminishes autophagic response to exacerbate renal damage in Tallyho/Jng mice

miRNAs provide fine tuning of gene expression via inhibition of translation. miR-451 has a modulatory role in cell cycling via downregulation of mechanistic target of rapamycin. We aimed to test whether chronic systemic inhibition of miR-451 would enhance renal fibrosis (associated with deranged autophagy). Adult TallyHo/Jng mice (obese insulin resistant) were randomized to two treatment groups to receive either miR-451 inhibition [via a locked nucleic acid construct] or a similar scrambled locked nucleic acid control for 8 wk. All mice were fed a high-fat diet (60% kcal from fat) ad libitum and humanely euthanized after 12 wk. Kidneys and blood were collected for analysis. Renal expression of miR-451 was sixfold lower in inhibitor-treated mice compared with control mice. miR-451 inhibition increased kidney weight and collagen and glycogen deposition. Blood chemistry revealed significantly higher Na⁺ and anion gap (relative metabolic acidosis) in inhibitor-treated mice. Western blot analysis and immunohistochemistry of the kidney revealed that the inhibitor increased markers of renal injury and fibrosis, e.g., kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, transforming growth factor-β, 14-3-3 protein-ζ, mechanistic target of rapamycin, AMP-activated protein kinase-α, calcium-binding protein 39, matrix metallopeptidase-9, and the autophagy receptor sequestosome 1. In contrast, the inhibitor reduced the epithelial cell integrity marker collagen type IV and the autophagy markers microtubule-associated protein 1A/1B light chain 3B and beclin-1. Taken together, these results support a protective role for miR-451 in reducing renal fibrosis by enhancing autophagy in obese mice.

MicroRNA-451 as an Early Predictor of Chronic Kidney Disease in Diabetic Nephropathy

Background

Diabetes mellitus is the leading cause of end-stage renal disease worldwide. Microalbuminuria is the cornerstone for the diagnosis of diabetic nephropathy. However, it is an inadequate marker for early diagnosis. MicroRNAs are not only new and promising markers for early diagnosis but also, but they may also play a role in the prevention of disease progression.

Methods

This study included ninety patients with type 2 DM in addition to 30 control subjects. MicroRNA-451 expression in blood and plasma using real-time PCR was evaluated in addition to the classic diabetic nephropathy markers (serum creatinine, urinary albumin, and eGFR).

Results

There was a significant difference between the studied groups versus control regarding serum creatinine, eGFR, urinary, and plasma microRNA-451 with p=0.0001. Patients with eGFR 60 ml/min/1.73 m² showed a significantly higher plasma microRNA-451 (29.6 ± 1.6) and significantly lower urinary microRNA-451 (21 ± 0.9) in comparison to patients with eGFR >60 ml/min/1.73 m² and p=0.0001. eGFR showed a positive correlation with urinary microRNA-451 and negative correlation with both plasma microRNA-451 and urinary albumin. Both plasma and urinary microRNA-451 are highly sensitive and specific markers for chronicity in diabetic nephropathy patients with sensitivity of 90.9% and 95.5% and specificity of 67.6% and 95.6%, respectively.

Conclusion

MicroRNA-451 is a promising early biomarker for chronic kidney disease in diabetic nephropathy with high sensitivity and specificity.

Decreased secretion and profibrotic activity of tubular exosomes in diabetic kidney disease

Tubular changes contribute to the development of renal pathologies in diabetic kidney disease (DKD), including interstitial fibrosis. It is unclear how tubular cells relay signals to interstitial fibroblasts. Recently, exosomes have been recognized as crucial mediators of intercellular communication. We hypothesized that exosomes secreted from tubular cells may stimulate fibroblasts for interstitial fibrosis in DKD. In this study, we isolated and purified exosomes from the renal cortex of DKD mice and high glucose-treated mouse proximal tubular cells. Compared with nondiabetic mice, exosome secretion in kidney tissues decreased in DKD mice. Likewise, high glucose incubation reduced exosome secretion in mouse kidney proximal tubular BUMPT cells. To study the effect of tubular cell exosomes on fibroblasts, exosomes from BUMPT cells were added to renal fibroblast NRK-49F cell cultures. Notably, exosomes from high glucose conditioned BUMPT cells induced higher proliferation, significant morphological change, and substantial production of fibronectin, α-smooth muscle actin, and collagen type Ι in NRK-49F fibroblasts. Proteomics analysis was further performed to profile the proteins within tubular cell exosomes. Interestingly, 22 proteins were found to be differentially expressed between tubular exosomes derived from high glucose conditioned cells and those from normal glucose conditioned cells. Cytoscape analysis suggested the existence of two protein-protein interaction networks in these exosomal differentially expressed proteins. While one of the protein-protein interaction networks comprised enolase 1 (Eno1), heat shock protein family A member 8 (Hspa8), thioredoxin 1 (Txn1), peptidylprolyl isomerase A (Ppia), phosphoglycerate kinase 1 (Pgk1), DNA topoisomerase II-β (Top2b), and β-actin (Actb), the other had the family proteins of human leucocyte antigen F (Ywhag), a component of the ND10 nuclear body (Ywhae), interferon regulatory factor-8 (Ywhaq), and human leucocyte antigen A (Ywhaz). Gene expression analysis via Nephroseq showed a correlation of Eno1 expression with DKD clinical manifestation. In conclusion, DKD is associated with a decrease in exosome secretion in renal tubular cells. Exosomes from high glucose conditioned tubular cells may regulate the proliferation and activation of fibroblasts, contributing to the paracrine signaling mechanism responsible for the pathological onset of renal interstitial fibrosis in DKD.

DACH1, a novel target of miR-218, participates in the regulation of cell viability, apoptosis, inflammatory response, and epithelial-mesenchymal transition process in renal tubule cells treated by high-glucose

Objective: This report was designed to assess the functional role of miR-218/dachshund family transcription factor 1 (DACH1) in diabetic kidney disease (DKD) and investigate its possible molecular mechanism.Materials and Methods: From the GEO database, we downloaded different datasets for analyzing the expression of miR-218 and DACH1 in DKD. TargetScan was adopted to predict the binding sites between miR-218 and DACH1, which was further verified by dual-luciferase reporter assays. The renal proximal tubule cells (HK-2) treated with high glucose (HG) were used as an in vitro model. QRT-PCR and western blot were used to determine the expression of DACH1 and other relative factors. Cell counting kit-8 and flow cytometer were applied to detect cell viability and apoptosis. The levels of inflammatory cytokines were determined by an ELISA assay.Results: A prominent raise of miR-218 was observed in DKD through bioinformatics analysis, which was further confirmed in the HG-induced model. DACH1 is a target of miR-218. miR-218 reduced cell viability and induced apoptosis by negatively regulating DACH1. Moreover, upregulating miR-218 in HG models increased the concentrations of pro-inflammatory cytokines TNF-α and IL-1β, reduced the level of anti-inflammatory cytokine IL-10, and promoted the epithelial-mesenchymal transition (EMT) process, which is possibly achieved by targeting DACH1. While downregulating miR-218 showed the opposite results.Conclusion: These data demonstrated that, under an in vitro HG environment, miR-218 suppressed the HK-2 cells proliferation, promoted apoptosis, caused an inflammatory response, and facilitated the EMT process largely by targeting DACH1, providing an insight into the therapeutic intervention of DKD.

miR-451 Loaded Exosomes Are Released by the Renal Cells in Response to Injury and Associated With Reduced Kidney Function in Human

Micro-RNAs (miRs) encapsulated inside urinary exosomes (uEs) have the potential as early biomarkers. Previously, we reported that a rise in uE miR-451 predicted albuminuria in diabetic rats; however, whether the rise was protective or detrimental, and occurred in response to injury or general hyperglycemia, was unknown. To address this, we studied both human and rat models of renal disease. In humans, uE miR-451 was approximately twofold higher in subjects with early-stage chronic kidney disease (CKD; serum creatinine < 2.0 mg/dl; n = 28), as compared to age-matched healthy controls (n = 23), and had a significant negative correlation with estimated glomerular filtration rate (eGFR) (r² = −0.10, p = 0.01). Subgroup analysis of CKD subjects showed that those without diabetes had slightly (∼30%) but significantly higher uE miR-451 as compared to those with diabetes, with no differences in albumin excretion, eGFR, serum sodium, and potassium. Using human proximal tubule (hPT) cells, we found that locked nucleic acid (LNA) inhibition of miR-451 resulted in a significant increase in the messenger RNA (mRNA) expression of kidney-injury-associated miR-451 targets, e.g., CAB39, TBX1, and YWHAZ, as compared to treatment with a control LNA. Moreover, hPT cells and their secreted exosomes showed an increase in miR-451 in response to mechanical injury but not high glucose (20 versus 5 mM). For further proof of concept, in diabetic rats, we showed that atorvastatin (AT), a treatment proven to attenuate renal injury without affecting systemic glucose levels, reduced uE miR-451 with the concomitant restoration of renal miR-451. These data elucidate the stimuli for renal miR-451 expression and exosomal release and support its role as a therapeutic target and early biomarker for renal injury in humans.

MiR-92b-3p is Induced by Advanced Glycation End Products and Involved in the Pathogenesis of Diabetic Nephropathy

Purpose

The current study aims to examine the effects of advanced glycation end products (AGEs) on the microRNA (miRNA) expression profile in the kidney tissues of rats.

Methods

Wistar rats were randomly divided into three equal experiment groups: the AGE group, the RSA group, and the control group. The rats in the AGE group and the RSA group were administered with advanced glycation end products (AGEs) and rat serum albumin (RSA) via the tail vein, respectively, whereas the control group received PBS. Total RNA was prepared from the rat kidney tissues, and the miRNA expression profiles in different experiment groups were compared by microarray analysis. The expression levels of selected differential miRNAs were verified by RT-qPCR. Target gene prediction was conducted using algorithms such as TargetScan, miRanda, and PICTar. Functional analysis was performed to determine the putative biological roles of the validated miRNAs.

Results

The microarray study revealed 451 upregulated and 320 downregulated miRNAs in the AGE group compared with the RSA group (p < 0.05). Seven miRNAs, including miR-21-5p, miR-92b-3p, miR-140-3p, miR-196a-5p, miR-181b-5p, miR-186-5p, and miR-192-5p, were screened and verified using RT-qPCR, of which, the change of miR-92b-3p was the most obvious according to the miRNA expression different multiple and p < 0.05). Seven miRNAs, including miR-21-5p, miR-92b-3p, miR-140-3p, miR-196a-5p, miR-181b-5p, miR-186-5p, and miR-192-5p, were screened and verified using RT-qPCR, of which, the change of miR-92b-3p was the most obvious according to the miRNA expression different multiple and

Conclusion

The results of the current study suggested that miR-92b-3p could mediate AGE-induced development of renal abnormalities through targeting Smad7 in rats with DN.

Interactions Among Non-Coding RNAs in Diabetic Nephropathy

Diabetic Nephropathy (DN) is the most common cause of End-stage renal disease (ESRD). Although various treatments and diagnosis applications are available, DN remains a clinical and economic burden. Recent findings showed that noncoding RNAs (ncRNAs) play an important role in DN progression, potentially can be used as biomarkers and therapeutic targets. NcRNAs refers to the RNA species that do not encode for any protein, and the most known ncRNAs are the microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). Dysregulation of these ncRNAs was reported before in DN patients and animal models of DN. Importantly, there are some interactions between these ncRNAs to regulate the crucial steps in DN progression. Here, we aimed to discuss the reported ncRNAs in DN and their interactions with critical genes in DN progression. Elucidating these ncRNAs regulatory network will allow for a better understanding of the molecular mechanisms in DN and how they can act as new biomarkers for DN and also as the potential targets for treatment.

Circulating human microRNA biomarkers of oxalic acid-induced acute kidney injury

Oxalic acid-induced nephrotoxicity and acute kidney injury result from formation of calcium oxalate crystals. Oxalic acid-induced acute kidney injury is a significant problem in many parts of the world. Circulating biomarkers that can accurately and reproducibly detect acute kidney injury are highly desirable. We used a high sensitivity discovery platform to identify signature microRNAs to distinguish healthy individuals never exposed to oxalic acid (n = 4) from those who were exposed to oxalic acid but had no injury (NOAKI; n = 4), moderate injury (AKIN2; n = 4) or severe injury (AKIN3; n = 4). Longitudinal analyses identified 4-8 h post-ingestion as the best time to detect AKIN2/3. We validated a signature of 53 microRNAs identified in the discovery, in a second cohort of individuals exposed to oxalic acid (NOAKI = 11, AKIN2 = 8 and AKIN3 = 18) and healthy controls (n = 19). Thirteen microRNAs were significantly downregulated in acute kidney injury patients compared to NOAKI within 8-h post-ingestion. Five microRNAs (miR-20a, miR-92a, miR-93, miR-195, miR-451) had a highly significant correlation with normalized urinary albumin, serum creatinine at 24 h and creatinine clearance. Logistic regression of these microRNAs had AUC-ROC of 0.85 predicting AKIN2/3 and discriminated patients from healthy controls (AUC-ROC = 0.93). mRNA targets of these microRNAs identified oxidative stress pathways of nephrotoxicity in proximal tubule and glomeruli nephrotoxicity. In conclusion, the downregulation of multiple circulating microRNAs in patients correlated with the severity of oxalic acid-induced acute kidney injury. A set of microRNAs (miR-20a, miR-92a, miR-93, miR-195, miR-451) could be promising biomarkers for early detection of oxalic acid-induced acute kidney injury.

Evaluation of the associations between circulating microRNAs and kidney function in coronary angiography patients

Circulating microRNAs (miRNAs) have been linked to chronic kidney disease. Little is known about the association between circulating miRNAs and kidney function in patients at high cardiovascular risk. We therefore investigated the association between a panel of candidate miRNAs and kidney function, based on estimated glomerular filtration rate (eGFR), in two independent cohorts of patients undergoing coronary angiography. The present study totally included 438 patients undergoing coronary angiography, who were divided into a discovery cohort (n = 120) and a validation cohort (n = 318). A candidate miRNA panel comprising 50 renal miRNAs was selected from the literature, and expression levels of circulating miRNAs were determined by real-time PCR. Out of the initially tested candidate miRNAs, 38 miRNAs were sufficiently detectable in plasma. Their association with kidney function was evaluated in the discovery cohort. Associations of seven of these miRNAs with eGFR were significant after multiple testing correction via false discovery rate estimation. To verify obtained results, miRNAs with significant false discovery rates were further analyzed in the validation cohort. miR-106b-5p, miR-16-5p, miR-19b-3p, miR-20a-5p, miR-25-3p, and miR-451a proved to be significantly associated with eGFR also in the validation cohort (all P < 0.001). Association between the identified renal miRNAs and kidney function was confirmed by analysis of covariance adjusting for age, sex, type 2 diabetes, hypertension, and albumin-to-creatinine ratio. In conclusion, our study showed that miR-16-5p, miR-19b-3p, miR-20a-5p, miR-25-3p, miR-106b-5p, and miR-451a are significantly linked to kidney function in patients undergoing coronary angiography.

MicroRNA-451 inhibits inflammation and proliferation of glomerular mesangial cells through down-regulating PSMD11 and NF-κB p65

The present study aimed to investigate the regulatory roles of microRNA-451 (miR-451) on the inflammation and proliferation of glomerular mesangial cells (GMCs) under high-glucose condition, and reveal the potential mechanisms related to 26S proteasome non-ATPase regulatory subunit 11 (PSMD11) and nuclear factor-κ B (NF-κB) signaling. The interaction between PSMD11 and miR-451 was identified by dual luciferase reporter (DLR) gene assay. GMCs were treated with 5.6 mmol/l (normal, L-GMCs) and 30 mmol/l glucose (high-glucose, H-GMCs), respectively. After transfecting with pcDNA3.1-PSMD11 and/or miR-451 mimics, the expression of miR-451, PSMD11, inhibitor of NF-κB α (IκBα), phosphorylated IκBα (p-IκBα), NF-κB p65, COX-2, and cyclinD1 were detected in H-GMCs by quantitative real-time PCR (qRT-PCR) and/or Western blot. The levels of interleukin (IL)-1β, IL-6, and IL-8, cell cycle, and viability was detected by enzyme-linked immunosorbent assay, flow cytometry, and MTT assay, respectively. MiR-451 was up-regulated in H-GMCs, and negatively regulated its target PSMD11 (P<0.05). H-GMCs exhibited significantly higher levels of IL-1β, IL-6, and IL-8, cell viability, and p-IκBα, NF-κB, COX-2, and cyclinD1 expression than L-GMCs (P<0.05). The transfection of miR-451 mimics significantly decreased the levels of IL-1β, IL-6, and IL-8, inhibited the cell viability via blocking cells in G0/G1 phase, and down-regulated p-IκBα, NF-κB p65, COX-2, and cyclinD1 in H-GMCs (P<0.05). The regulatory effects of miR-451 mimics on H-GMCs were reversed by the transfection of PSMD11 (P<0.05). The up-regulation of miR-451 inhibits the inflammation and proliferation of H-GMCs through down-regulating PSMD11 and NF-κB p65.

MiRNA-802 suppresses proliferation and migration of epithelial ovarian cancer cells by targeting YWHAZ

Background

The imbalance of expression of microRNA-802 may have a significant place in tumor progression. However, the bio-function of epithelial ovarian cancer cells remains unclear. Therefore, we setup this study to explore the pathogenesis of epithelial ovarian cancer based on microRNA-802.

Methods

RT-qPCR analysis was used to measure the expression level of microRNA802 and YWHAZ in epithelial ovarian cancer. CCK-8, colony formation, flow cytometry and transwell assay were used to detect the effects of microRNA-802 on cell proliferation, apoptosis, invasion and migration. Target gene prediction and screening, luciferase reporting experiments were applied to validate the downstream target genes of microRNA-802. The effects of microRNA-802 on the expression of YWHAZ and its biological effects were measured by Western blotting and RT-qPCR.

Results

Compared with normal cell lines and tissues, the expression level of microRNA-802 was obviously down-regulated in cancer related cell lines and tissues. Overexpression of microRNA-802 could obviously inhibit the invasion and proliferation and induce apoptosis. In addition, YWHAZ was the binding target protein of miR-802 for epithelial ovarian cancer cells. YWHAZ was obviously up-regulated in human epithelial ovarian cancer cells, and YWHAZ was negatively correlated with the expression of miR-802. YWHAZ can partly eliminate the inhibitory effect caused by overexpression of miR-802 on growth and metastasis of epithelial ovarian cancer cells.

Conclusion

miR-802 can regulate the occurrence and development of epithelial ovarian cancer by targeting YWHAZ.

MicroRNA-326 Inhibits Apoptosis and Promotes Proliferation of Dopaminergic Neurons in Parkinson's Disease Through Suppression of KLK7-Mediated MAPK Signaling Pathway

Parkinson's disease (PD), one of the motor system disorders, is characterized by the loss of dopamine-producing brain cells. Accumulating evidence has highlighted the involvement of microRNAs (miRs) in the development and progression of PD. Hence, we aimed at exploring possible effects of miR-326 on the progression of PD in mice in an attempt to elucidate the underlying mechanism associated with the kallikrein-related peptidase 7 (KLK7)-mediated mitogen-activated protein kinase (MAPK) signaling pathway. In order to identify the regulatory relationship between miR-326 and KLK7 and its biological significance in PD, PD mouse models were established and subsequently treated with mimics or inhibitors of miR-326 or siRNA-KLK7. The content of striatal dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyrosine (3-MT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA); positive expression of tyrosine hydroxylase (TH) and inducible nitric oxide synthase (iNOS); and the levels of IL-1, IL-6, TNF-α, INF-γ, and MAPK signaling pathway-related genes were determined accordingly. The results obtained indicated that KLK7 was negatively targeted by miR-326, with lower miR-326 and higher KLK7 detected among PD mice. The overexpression of miR-326 or silencing of KLK7 was demonstrated to increase the content of DA, DOPAC, HVA, 3-MT, SOD, GSH-Px, and TH positive expression, while reducing iNOS positive expression, MDA content and cell apoptosis, as well as inhibited levels of IL-1, IL-6, TNF-α, INF-γ, and mRNA and protein levels of p38, ERK, JNK, and caspase-3. Taken together, these results provided evidence suggesting that miR-326 could inhibit iNOS activation and apoptosis of dopaminergic neurons through inhibiting the MAPK signaling pathway and negatively regulating KLK7 in mice with PD. These findings highlight the potential of miR-326 as a novel target for future PD treatment.

MicroRNA as novel biomarkers and therapeutic targets in diabetic kidney disease: An update

Diabetic kidney disease (DKD) is a life-limiting condition characterized by progressive and irreversible loss of renal function. Currently, the estimated glomerular filtration rate (eGFR) and albuminuria are used as key markers to define DKD. However, they may not accurately indicate the degree of renal dysfunction and injury. Current therapeutic approaches for DKD, including attainment of blood pressure goals, optimal control of blood glucose and lipid levels, and the use of agents to block the renin-angiotensin-aldosterone system (RAAS) can only slow the progression of DKD. Hence, early diagnosis and innovative strategies are needed to both prevent and treat DKD. In recent years, a novel class of noncoding RNA, microRNAs (miRNAs) are reported to be involved in all biological processes, including cellular proliferation, apoptosis, and differentiation. miRNAs are small noncoding RNAs that regulate gene expression by posttranscriptional and epigenetic mechanisms. They are found to be in virtually all body fluids and used successfully as biomarkers for various diseases. Urinary miRNAs correlate with clinical and histologic parameters in DKD and differential urinary miRNA expression patterns have been reported. Kidney fibrosis is the common end stage of various CKD including DKD. Transforming growth factor-β(TGF-β) is regarded as the master regulator of kidney fibrosis, which is likely at least in part through regulating miRNA expression. miRNA are widely involved in the progression of DKD via many molecular mechanisms. In this review, the involvement of miRNA in fibrosis, inflammation, hypertrophy, autophagy, endoplasmic reticulum (ER) stress, oxidative stress, insulin resistance, and podocyte injury will be discussed, as these mechanisms are believed to offer new therapeutic targets that can be exploited to develop important treatments for DKD over the next decade.

A comprehensive review on miR-451: A promising cancer biomarker with therapeutic potential

MicroRNAs (miRNAs) are proposed as a family of short noncoding molecules able to manage and control the expression of the gene targets at the posttranscriptional level. They contribute in several fundamental physiological mechanisms as well as a verity of human and animal diseases such as cancer progression. Among these tiny RNAs, miR-451 placed on chromosome 17 at 17q11.2 presents an essential role in many biological processes in health condition and also in pathogenesis of different diseases. Besides, it has been recently considered as a valuable biomarker for cancer detection, prognosis and treatment. Therefore, this review will provide the critical functions of miR-451 on biological mechanisms including cell cycle and proliferation, cell survival and apoptosis, differentiation and development as well as disease initiation and progression such as tumor formation, migration, invasion, and metastasis.

MicroRNA-451 inhibits vascular smooth muscle cell migration and intimal hyperplasia after vascular injury via Ywhaz/p38 MAPK pathway

Increasing evidence has indicated that intimal hyperplasia is a common event in the pathophysiology of many vascular diseases including atherosclerosis (AS). Recently, deregulated microRNAs (miRNAs) have been reported to be associated with the pathophysiology of AS. However, the biological function and regulatory mechanisms of miRNAs in intimal hyperplasia in AS remain largely unclear. The aim of this study was to investigate the effects of miRNAs on intimal hyperplasia and reveal the underlying mechanisms of their effects. Firstly, the model of rat vascular injury was successfully constructed in vivo. Then, the miRNAs expression profiles were analyzed by miRNA microarray. It was observed that miR-451 was significantly downregulated in injury carotid arteries. Subsequently, we investigated miR-451 function and found that upregulation of miR-451 by agomir-451 improves intimal thickening in rats following vascular injury. It was also observed that miR-451 was downregulated in the VSMCs following platelet-derived growth factor type BB (PDGF-BB) stimulation. The upregulation of miR-451 attenuated PDGF-BB-induced VSMCs injury, as evidenced by inhibition of proliferation, invasion and migration. Besides, overexpression of miR-451 blocked the activation of p38 MAPK signaling pathway in PDGF-BB treated VSMCs, as demonstrated by the downregulation of phosphorylated (p-) p38. In addition, Ywhaz, a positive regulator of p38 MAPK signaling pathway, was found to be a direct target of miR-451 in the VSMCs and this was validated using a luciferase reporter assay. Overexpression of Ywhaz partially abolished the inhibitory effects of miR-451 overexpression on PDGF-BB induced VSMCs injury. Collectively, these findings indicated that miR-451 protected intimal hyperplasia and PDGF-BB-induced VSMCs injury by Ywhaz/p38 MAPK pathway, and miR-451 may be considered as a potential therapeutic target in the treatment of AS.

microRNAs in chronic kidney disease

Chronic kidney disease (CKD) results in high morbidity and mortality worldwide causing a huge socioeconomic burden. MicroRNA (miRNA) exert critical regulatory functions by targeting downstream genes and have been associated with many pathophysiologic processes including CKD. In fact, many studies have shown that the expression of various miRNAs was significantly changed in CKD. Current investigations have focused on revealing the relationship between miRNAs and CKD states including diabetic nephropathy, lupus nephritis, focal segmental glomerulosclerosis and IgA nephropathy. In this review, we summarize the latest advances elucidating miRNA involvement in the progression of CKD and demonstrate that miRNAs have the potential to be effective biomarkers and therapeutic targets for subsequent treatment.

Mesenchymal stem cells-microvesicle-miR-451a ameliorate early diabetic kidney injury by negative regulation of P15 and P19

Microvesicles (MVs) from mesenchymal stem cells (MSCs) have been reported as a new communicated way between cells. This study evaluated the influence and underlying mechanism of MVs-shuttled miR-451a on renal fibrosis and epithelial mesenchymal transformation (EMT) in diabetic nephropathy (DN) with hyperuricemia. MVs were isolated from MSCs-cultured medium by gradient ultracentrifugation. The level of miR-451a in MSCs and MVs was analyzed by qPCR. The changes of miR-451a, E-cadherin, α-SMA, P15INK4b (P15), and P19INK4d (P19) were measured in hyperglycosis and hyperuricemia-induced cell (HK-2) and mouse models. The changes of cell cycle were analyzed by flow cytometry. The ability of proliferation and viability was measured by BrdU and CCK8, respectively. Dual-luciferase reporter assays were conducted to determine the target binding sites. The renal function and histological changes of mice were analyzed. MVs showed the same surface markers as MSCs but much higher miR-451a expression (4.87 ± 2.03 fold higher than MSCs). miR-451a was decreased to 26% ± 11% and 6.7% ± 0.82% in injured HK-2 cells and kidney, respectively. MV-miR-451a enhanced the HK2 cells proliferation and viability in vitro, and decreased the morphologic and functional injury of kidney in vivo. Moreover, infusion of MV-miR-451a reduced the level of α-SMA and raised E-cadherin expression. These effects were responsible for the improved arrested cell cycle and down-regulation of P15 and P19 via miR-451a targeting their 3′-UTR sites. This study demonstrated that MSC–MV-miR-451a could inhibit cell cycle inhibitors P15 and P19 to restart the blocked cell cycle and reverse EMT in vivo and in vitro, and thus miR-451a is potentially a new target for DN therapy.

Impact statement

The mechanism of MSCs repairing the injured kidney in diabetic nephropathy is not yet clear. In the research, MVs showed the same surface markers as MSCs but much higher MiR-451a expression. miR-451a was decreased in both injured HK-2 cells and kidneys. MV-miR-451a stimulated the cell proliferation and viability in vitro and promoted structural and functional improvements of injured kidney in vivo. Infusion of MV-miR-451a ameliorated EMT by reducing α-SMA and increasing E-cadherin. These effects relied on the improved cell cycle arrest and the down-regulation of P15 and P19 via miR-451a binding to their 3′-UTR region. This study demonstrated that MSC–MV-miR-451a could specifically inhibit cell cycle inhibitors to restart the blocked cell cycle and reverse EMT in vivo and in vitro. Therefore, miR-451a may be a new target for DN therapy.

MicroRNA-451a overexpression induces accelerated neuronal differentiation of Ntera2/D1 cells and ablation affects neurogenesis in microRNA-451a-/- mice

MiR-451a is best known for its role in erythropoiesis and for its tumour suppressor features. Here we show a role for miR-451a in neuronal differentiation through analysis of endogenous and ectopically expressed or silenced miR-451a in Ntera2/D1 cells during neuronal differentiation. Furthermore, we compared neuronal differentiation in the dentate gyrus of hippocampus of miR-451a^-/- and wild type mice. MiR-451a overexpression in lentiviral transduced Ntera2/D1 cells was associated with a significant shifting of mRNA expression of the developmental markers Nestin, βIII Tubulin, NF200, DCX and MAP2 to earlier developmental time points, compared to control vector transduced cells. In line with this, accelerated neuronal network formation in AB.G.miR-451a transduced cells, as well as an increase in neurite outgrowth both in number and length was observed. MiR-451a targets genes MIF, AKT1, CAB39, YWHAZ, RAB14, TSC1, OSR1, POU3F2, TNS4, PSMB8, CXCL16, CDKN2D and IL6R were, moreover, either constantly downregulated or exhibited shifted expression profiles in AB.G.miR-451a transduced cells. Lentiviral knockdown of endogenous miR-451a expression in Ntera2/D1 cells resulted in decelerated differentiation. Endogenous miR-451a expression was upregulated during development in the hippocampus of wildtype mice. In situ hybridization revealed intensively stained single cells in the subgranular zone and the hilus of the dentate gyrus of wild type mice, while genetic ablation of miR-451a was observed to promote an imbalance between proliferation and neuronal differentiation in neurogenic brain regions, suggested by Ki67 and DCX staining. Taken together, these results provide strong support for a role of miR-451a in neuronal maturation processes in vitro and in vivo.

Neuroprotective effects of overexpressed microRNA-200a on activation of glaucoma-related retinal glial cells and apoptosis of ganglion cells via downregulating FGF7-mediated MAPK signaling pathway

Glaucoma is a progressive optic neuropathy and is one of the leading causes of blindness in the industrialized countries. The involvement of microRNAs (miRs) has been implicated in regulating the complex biological responses to changes in intraocular pressure. However, the therapeutic role of miR-200a on glaucoma has not been well studied yet. In this study, we confirmed the role of miR-200a in glaucoma progression and identified the related mechanism. Microarray expression profiles were used to screen the glaucoma-related genes. The relationship between miR-200a and FGF7 was validated by bioinformatics analysis and dual-luciferase reporter gene assay. Glaucoma-related parameters including the expression of CD11b and iNOS, activation of Muller cells, and apoptosis of retinal ganglion cells (RGCs) in the mouse model were measured by immunohistochemistry, MTT assay and TUNEL assay, respectively. miR-200a was reduced in glaucoma, whereas FGF7 was robustly induced. Thereby, we speculated that FGF7 was negatively regulated by miR-200a. Downregulated miR-200a could activate the MAPK signaling pathway following elevations in ERK, JNK, p38 and Bax expression and reduction in Bcl-2 expression. In the mouse model, downregulated miR-200a increased the expression of CD11b and iNOS and the apoptosis of RGCs, but stimulated the inactivation of Muller cells. However, the above-mentioned alternations induced by downregulated miR-200a were reversed after FGF7 repression. miR-200a can inhibit the FGF7-mediated MAPK signaling pathway and play a protective role on improving the glaucoma-induced optical nerve injury.

Noncoding RNAs as therapeutic targets in early stage diabetic kidney disease

Diabetic kidney disease (DKD) is a major renal complication of diabetes that leads to renal dysfunction and end-stage renal disease (ESRD). Major features of DKD include accumulation of extracellular matrix proteins and glomerular hypertrophy, especially in early stage. Transforming growth factor-β plays key roles in regulation of profibrotic genes and signal transducers such as Akt kinase and MAPK as well as endoplasmic reticulum stress, oxidant stress, and autophagy related to hypertrophy in diabetes. Many drugs targeting the pathogenic signaling in DKD (mostly through protein-coding genes) are under development. However, because of the limited number of protein-coding genes, noncoding RNAs (ncRNAs) including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are attracting more attention as potential new drug targets for human diseases. Some miRNAs and lncRNAs regulate each other (by hosting, enhancing transcription from the neighbor, hybridizing each other, and changing chromatin modifications) and create circuits and cascades enhancing the pathogenic signaling in DKD. In this short and focused review, the functional significance of ncRNAs (miRNAs and lncRNAs) in the early stages of DKD and their therapeutic potential are discussed.

A Novel Regulator of Type II Diabetes: MicroRNA-143

MiR-143 is an miRNA with the function of specifically inhibiting the insulin-AKT pathway via the downregulation of oxysterol-binding protein-related protein 8 (ORP8), thus resulting in the inhibition of AKT phosphorylation, insulin tolerance, and final development of type II diabetes mellitus (T2DM). Aerobic exercise can prevent T2DM by downregulating miR-143. However, the underlying mechanisms for exercise-induced change of miR-143 remain unclear. In the present study, we will summarize the involvement of miR-143 in regulating the development of T2DM and the underlying mechanisms for potential diagnosis, prevention, and treatments, including exercise intervention for T2DM by targeting miR-143.

Plasma microRNA panel is a novel biomarker for focal segmental glomerulosclerosis and associated with podocyte apoptosis

Focal segmental glomerulosclerosis (FSGS) is a frequent glomerular disease, and is the common cause of nephrotic syndrome. However, there is no validated diagnostic blood biomarker for FSGS. Here, we performed a real-time PCR-based high-throughput miRNA profiling to identify the plasma signature for FSGS. We found four miRNAs (miR-17, miR-451, miR-106a, and miR-19b) were significantly downregulated in the plasma of FSGS patients (n = 97) compared with healthy controls (n = 124) in the training, validation, and blinded-test phases. The miRNA panel produced an AUC value of 0.82, and was associated with FSGS severity and histologic classification. A three-miRNA panel, including miR-17, miR-451, and miR-106a was related to FSGS remission. Furthermore, the downregulation of plasma-miRNA signature was not detected in disease controls (n = 119) such as IgA nephropathy (IgAN), mesangial proliferative glomerulonephritis (MSPGN), and membranous nephropathy (MN), and the miRNA panel discriminated between FSGS and disease controls. Pathway analysis showed that the four-miRNA panel may cooperatively regulate the pathways involved in the development of FSGS, such as apoptosis. We identified that phosphatase and tensin homolog (PTEN), Bcl-2-like protein 11 (BCL2L11), and chemokine (C-X-C motif) ligand 14 (CXCL14) were targets of miR-106a in human podocyte. Additionally, miR-106a overexpression suppressed podocyte apoptosis in vitro and the downregulation of four-miRNA panel probably resulted in the enhanced apoptosis in podocyte during FSGS development. Taken together, our data show that the plasma-miRNA panel is a potential independent diagnostic and prognostic factor for FSGS. Above miRNAs are involved in FSGS pathogenesis through regulating podocyte apoptosis.

gga-miR-451 Negatively Regulates Mycoplasma gallisepticum (HS Strain)-Induced Inflammatory Cytokine Production via Targeting YWHAZ

Mycoplasma gallisepticum (MG) is the most economically significant mycoplasma pathogen of poultry that causes chronic respiratory disease (CRD) in chickens. Although miRNAs have been identified as a major regulator effect on inflammatory response, it is largely unclear how they regulate MG-induced inflammation. The aim of this study was to investigate the functional roles of gga-miR-451 and identify downstream targets regulated by gga-miR-451 in MG infection of chicken. We found that the expression of gga-miR-451 was significantly up-regulated during MG infection of chicken embryo fibroblast cells (DF-1) and chicken embryonic lungs. Overexpression of gga-miR-451 decreased the MG-induced inflammatory cytokine production, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), whereas inhibition of gga-miR-451 had the opposite effect. Gene expression data combined with luciferase reporter assays demonstrated that tyrosine3-monooxygenase/tryptophan5-monooxygenase activation protein zeta (YWHAZ) was identified as a direct target of gga-miR-451 in the context of MG infection. Furthermore, upregulation of gga-miR-451 significantly inhibited the MG-infected DF-1 cells proliferation, induced cell-cycle arrest, and promoted apoptosis. Collectively, our results demonstrate that gga-miR-451 negatively regulates the MG-induced production of inflammatory cytokines via targeting YWHAZ, inhibits the cell cycle progression and cell proliferation, and promotes cell apoptosis. This study provides a better understanding of the molecular mechanisms of MG infection.

New insights on microRNAs in diabetic nephropathy: potential biomarkers for diagnosis and therapeutic targets

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus associated with the progressive deterioration of renal function. Although microalbuminuria is considered as a gold standard for DN diagnosis, it has limited predictive powers and specificity as a diagnostic tool for the early stage of DN. Therefore, new biomarkers are required for the early detection of DN. Studies using in vitro and in vivo models of DN have revealed an important role of microRNAs (miRNAs), short non-coding RNAs that modulate physiological and pathological processes by inhibiting target gene expression, in DN development. Recent studies have shown that the dysregulation of miRNAs, which is associated with the key features of DN, such as the mesangial expansion and accumulation of extracellular matrix proteins, is related to fibrosis and glomerular dysfunction. Thus, the up- and downregulation of miRNA expression in the renal tissue or biological fluids, including urine, may represent new biomarkers for the diagnosis and monitoring of DN progression. In this review, we highlight the significance of miRNAs as biomarkers for the early detection of DN and emphasise their potential role as a therapeutic target.

The miR-30 family: Versatile players in breast cancer

The microRNA family, miR-30, plays diverse roles in regulating key aspects of neoplastic transformation, metastasis, and clinical outcomes in different types of tumors. Accumulating evidence proves that miR-30 family is pivotal in the breast cancer development by controlling critical signaling pathways and relevant oncogenes. Here, we review the roles of miR-30 family members in the tumorigenesis, metastasis, and drug resistance of breast cancer, and their application to predict the prognosis of breast cancer patients. We think miR-30 family members would be promising biomarkers for breast cancer and may bring a novel insight in molecular targeted therapy of breast cancer.

Epigenetics of kidney disease

DNA methylation and histone modifications determine renal programming and the development and progression of renal disease. The identification of the way in which the renal cell epigenome is altered by environmental modifiers driving the onset and progression of renal diseases has extended our understanding of the pathophysiology of kidney disease progression. In this review, we focus on current knowledge concerning the implications of epigenetic modifications during renal disease from early development to chronic kidney disease progression including renal fibrosis, diabetic nephropathy and the translational potential of identifying new biomarkers and treatments for the prevention and therapy of chronic kidney disease and end-stage kidney disease.

miRNAs: Nanomachines That Micromanage the Pathophysiology of Diabetes Mellitus

Diabetes mellitus (DM) refers to a combination of heterogeneous complex metabolic disorders that are associated with episodes of hyperglycemia and glucose intolerance occurring as a result of defects in insulin secretion, action, or both. The prevalence of DM is increasing at an alarming rate, and there exists a need to develop better therapeutics and prognostic markers for earlier detection and diagnosis. In this review, after giving a brief introduction of diabetes mellitus and microRNA (miRNA) biogenesis pathway, we first describe various in vitro and animal model systems that have been developed to study diabetes. Further, we elaborate on the significant roles played by miRNAs as regulators of gene expression in the context of development of diabetes and its secondary complications. The different approaches to quantify miRNAs and their potential to be used as therapeutic targets for alleviation of diabetes have also been discussed.

Urinary chromium is associated with changes in leukocyte miRNA expression in obese subjects

BACKGROUND/OBJECTIVES

Epidemiological studies suggest a link between chromium (Cr) status and cardiovascular disease. Increased urinary excretion of Cr was reported in subjects with diabetes compared with non-diabetic controls and those with non-diabetic insulin resistance. Epigenetic alterations have been linked to the presence of Cr, and microRNA (miRNA) expression has been implicated in the pathogenesis of metabolic diseases and cardiovascular diseases (CVDs). We investigated the association between Cr excretion and miRNA expression in leukocytes from obese subjects. We also examined the relationship between altered miRNA expression and selected clinical parameters to further investigate mechanisms linking Cr to metabolic diseases and CVDs.

SUBJECTS/METHODS

We analyzed urinary Cr in 90 Italian subjects using inductively coupled plasma-mass spectrometry. Peripheral blood miRNA levels were screened with TaqMan Low-Density Array Human MicroRNA A. Cr level-associated expression of miRNAs was detected with multivariate regression analyses, and the top 10 candidate miRNAs were selected for validation. We also used multivariate regression analyses to assess possible associations between validated miRNAs and glycated hemoglobin (A1c) and blood pressure (BP). The validated miRNAs were further investigated by functional analysis with Ingenuity Pathway Analysis software.

RESULTS

Urinary Cr levels (mean: 0.35 μg/l; s.d.=0.24) ranged from 0.05 to 1.27 μg/l. In the screening phase, 43 miRNAs were negatively associated with Cr. Of the top 10 miRNAs selected for validation, nine (miR-451, miR-301, miR-15b, miR-21, miR-26a, miR-362-3p, miR-182, miR-183 and miR-486-3p) were downregulated in association with Cr (P-false discovery rate (FDR)<0.10). miR-451 expression was associated with A1c (β=-0.06; P=0.0416), whereas miR-486-3p expression was associated both with diastolic (β=2.1; P=0.004) and systolic BP (β=3.3; P=0.003).

CONCLUSIONS

These results indicate that miR-451 and miR-486-3p are involved in the link between Cr levels and metabolic diseases and CVDs.

Inhibition of the processing of miR-25 by HIPK2-Phosphorylated-MeCP2 induces NOX4 in early diabetic nephropathy

Phosphorylated methyl-CpG binding protein2 (p-MeCP2) suppresses the processing of several microRNAs (miRNAs). Homeo-domain interacting protein kinase2 (HIPK2) phosphorylates MeCP2, a known transcriptional repressor. However, it is not known if MeCP2 and HIPK2 are involved in processing of miRNAs implicated in diabetic nephropathy. p-MeCP2 and HIPK2 levels were significantly increased, but Seven in Absentia Homolog1 (SIAH1), which mediates proteasomal degradation of HIPK2, was decreased in the glomeruli of streptozotocin injected diabetic mice. Among several miRNAs, miR-25 and its precursor were significantly decreased in diabetic mice, whereas primary miR-25 levels were significantly increased. NADPH oxidase4 (NOX4), a target of miR-25, was significantly increased in diabetic mice. Protein levels of p-MeCP2, HIPK2, and NOX4 were increased in high glucose (HG)- or TGF-β-treated mouse glomerular mesangial cells (MMCs). miR-25 (primary, precursor, and mature) and mRNA levels of genes indicated in the in vivo study showed similar trends of regulation in MMCs treated with HG or TGF-β. The HG- or TGF-β-induced upregulation of p-MeCP2, NOX4 and primary miR-25, but downregulation of precursor and mature miR-25, were attenuated by Hipk2 siRNA. These results demonstrate a novel role for the SIAH1/HIPK2/MeCP2 axis in suppressing miR-25 processing and thereby upregulating NOX4 in early diabetic nephropathy.

Regulatory Mechanisms of the Molecular Pathways in Fibrosis Induced by MicroRNAs

OBJECTIVE

MicroRNAs (miRNAs or miRs) play critical roles in the fibrotic process in different organs. We summarized the latest research progress on the roles and mechanisms of miRNAs in the regulation of the molecular signaling pathways involved in fibrosis.

DATA SOURCES

Papers published in English from January 2010 to August 2015 were selected from the PubMed and Web of Science databases using the search terms "microRNA", "miR", "transforming growth factor β", "tgf β", "mitogen-activated protein kinase", "mapk", "integrin", "p38", "c-Jun NH2-terminal kinase", "jnk", "extracellular signal-regulated kinase", "erk", and "fibrosis".

STUDY SELECTION

Articles were obtained and reviewed to analyze the regulatory effects of miRNAs on molecular signaling pathways involved in the fibrosis.

RESULTS

Recent evidence has shown that miRNAs are involved in regulating fibrosis by targeting different substrates in the molecular processes that drive fibrosis, such as immune cell sensitization, effector cell activation, and extracellular matrix remodeling. Moreover, several important molecular signaling pathways involve in fibrosis, such as the transforming growth factor-beta (TGF-β) pathway, mitogen-activated protein kinase (MAPK) pathways, and the integrin pathway are regulated by miRNAs. Third, regulation of the fibrotic pathways induced by miRNAs is found in many other tissues in addition to the heart, lung, liver, and kidney. Interestingly, the actions of many drugs on the human body are also induced by miRNAs. It is encouraging that the fibrotic process can be blocked or reversed by targeting specific miRNAs and their signaling pathways, thereby protecting the structures and functions of different organs.

CONCLUSIONS

miRNAs not only regulate molecular signaling pathways in fibrosis but also serve as potential targets of novel therapeutic interventions for fibrosing diseases.

miR-451 suppresses the NF-kappaB-mediated proinflammatory molecules expression through inhibiting LMP7 in diabetic nephropathy

Activation of nuclear factor -kappa B (NF-κB) is associated with inflammation in the progression of diabetic nephropathy (DN). MiR-451 is closely linked to renal damage in DN. Large multifunctional protease 7 (LMP7), an immunoproteasome subunit, can activate NF-κB. However, it remained unclear whether miR-451 affected NF-κB-induced inflammation by regulating LMP7 in DN. In this study, deep sequencing, in situ hybridization, quantitative real-time PCR, dual-luciferase reporter gene assays, western blot and chromatin immunoprecipitation were respectively used. For the results, we found that miR-451 was markedly downregulated in the kidneys of db/db mice, PBMCs of DN patients and mesangial cells (MCs) cultured in high glucose conditions. Furthermore, miR-451 directly targeted LMP7 expression to inhibit NF-κB activity, and down-regulated transcription of proinflammatory molecules in MCs. More importantly, in the kidneys of db/db DN mice, increasing miR-451 level inhibited LMP7/NF-κB activity, and attenuated the urinary microalbumin excretion, blood glucose, and glomerular injury. In conclusion, these results provide new insights into the regulation of miR-451 via the LMP7/NF-κB central inflammatory pathway during progression of DN.

Early detection of diabetic kidney disease: Present limitations and future perspectives

Diabetic kidney disease (DKD) is one of the most common diabetic complications, as well as the leading cause of chronic kidney disease and end-stage renal disease around the world. To prevent the dreadful consequence, development of new assays for diagnostic of DKD has always been the priority in the research field of diabetic complications. At present, urinary albumin-to-creatinine ratio and estimated glomerular filtration rate (eGFR) are the standard methods for assessing glomerular damage and renal function changes in clinical practice. However, due to diverse tissue involvement in different individuals, the so-called “non-albuminuric renal impairment” is not uncommon, especially in patients with type 2 diabetes. On the other hand, the precision of creatinine-based GFR estimates is limited in hyperfiltration status. These facts make albuminuria and eGFR less reliable indicators for early-stage DKD. In recent years, considerable progress has been made in the understanding of the pathogenesis of DKD, along with the elucidation of its genetic profiles and phenotypic expression of different molecules. With the help of ever-evolving technologies, it has gradually become plausible to apply the thriving information in clinical practice. The strength and weakness of several novel biomarkers, genomic, proteomic and metabolomic signatures in assisting the early diagnosis of DKD will be discussed in this article.

microRNAs in Diabetic Kidney Disease

Diabetes and diabetic kidney diseases have continually exerted a great burden on our society. Although the recent advances in medical research have led to a much better understanding of diabetic kidney diseases, there is still no successful strategy for effective treatments for diabetic kidney diseases. Recently, treatment of diabetic kidney diseases relies either on drugs that reduce the progression of renal injury or on renal replacement therapies, such as dialysis and kidney transplantation. On the other hand, searching for biomarkers for early diagnosis and effective therapy is also urgent. Discovery of microRNAs has opened to a novel field for posttranscriptional regulation of gene expression. Results from cell culture experiments, experimental animal models, and patients under diabetic conditions reveal the critical role of microRNAs during the progression of diabetic kidney diseases. Functional studies demonstrate not only the capability of microRNAs to regulate expression of target genes, but also their therapeutic potential to diabetic kidney diseases. The existence of microRNAs in plasma, serum, and urine suggests their possibility to be biomarkers in diabetic kidney diseases. Thus, identification of the functional role of microRNAs provides an essentially clinical impact in terms of prevention and treatment of progression in diabetic kidney diseases as it enables us to develop novel, specific therapies and diagnostic tools for diabetic kidney diseases.