The Function of MicroRNAs in Renal Development and Pathophysiology

Analysis of IL-17A, IL-17F, and miR-146a-5p Prior to Transplantation and Their Role in Kidney Transplant Recipients

Background/Objectives: The balance between regulatory and Th17 cells plays an important role in maintaining the immune tolerance after kidney transplantation (KTx) which is essential for transplantation success, defined as a long graft survival and an absence of organ rejection. The present study aimed to assess whether the pretransplant characteristics of IL-17A and IL-17F, their receptors, as well as miR-146a-5p, an miRNA associated with IL-17A/F regulation, can predict KTx outcomes. Methods: A group of 108 pre-KTx dialysis patients and 125 healthy controls were investigated for single nucleotide substitutions within genes coding for IL-17A, IL-17F, their IL-17RA/RC receptors, and miR-146a-5p. Genotyping was performed using LightSNiP assays. In addition, IL17-A/F serum concentrations were determined using ELISA while miR-146a-5p expression was analyzed by RT-PCR. Results: The IL-17F (rs763780) G allele prevailed in KTx recipients as compared to healthy individuals (OR = 23.59, p < 0.0001) and was associated with a higher IL-17F serum level (p = 0.0381) prior to transplantation. Higher miR-146a-5p expression before KTx was more frequently detected in recipients with an increased IL-17A serum concentration (p = 0.0177). Moreover, IL-17A (rs2275913) GG homozygosity was found to be associated with an increased incidence of deaths before KTx (OR = 4.17, p = 0.0307). T-cell or acute rejection episodes were more frequently observed among patients with the C allele of miR-146a-5p (rs2910164) (OR = 5.38, p = 0.0531). IL17-RA/-RC genetic variants (p < 0.05) seem to be associated with eGFR values. Conclusions: These results imply that IL-17F (rs763780) polymorphism is associated with the serum level of this cytokine and may be related to the risk of renal disease and transplant rejection together with miR-146a-5p (rs2910164), while the IL-17A (rs2275913) genotype may affect patients' survival before KTx.

The Functional Role of microRNAs and mRNAs in Diabetic Kidney Disease: A Review

Diabetes is a group of diseases marked by poor control of blood glucose levels. Diabetes mellitus (DM) occurs when pancreatic cells fail to make insulin, which is required to keep blood glucose levels stable, disorders, and so on. High glucose levels in the blood induce diabetic effects, which can cause catastrophic damage to bodily organs such as the eyes and lower extremities. Diabetes is classified into many forms, one of which is controlled by hyperglycemia or Diabetic Kidney Disease (DKD), and another that is not controlled by hyperglycemia (nondiabetic kidney disease or NDKD) and is caused by other factors such as hypertension, hereditary. DKD is associated with diabetic nephropathy (DN), a leading cause of chronic kidney disease (CKD) and end-stage renal failure. The disease is characterized by glomerular basement membrane thickening, glomerular sclerosis, and mesangial expansion, resulting in a progressive decrease in glomerular filtration rate, glomerular hypertension, and renal failure or nephrotic syndrome. It is also represented by some microvascular complications such as nerve ischemia produced by intracellular metabolic changes, microvascular illness, and the direct impact of excessive blood glucose on neuronal activity. Therefore, DKD-induced nephrotic failure is worse than NDKD. MicroRNAs (miRNAs) are important in the development and progression of several diseases, including diabetic kidney disease (DKD). These dysregulated miRNAs can impact various cellular processes, including inflammation, fibrosis, oxidative stress, and apoptosis, all of which are implicated during DKD. MiRNAs can alter the course of DKD by targeting several essential mechanisms. Understanding the miRNAs implicated in DKD and their involvement in disease development might lead to identifying possible therapeutic targets for DKD prevention and therapy. Therefore, this review focuses specifically on DKD-associated DN, as well as how in-silico approaches may aid in improving the management of the disease.

Immunomodulatory effects of probiotic supplementation in patients with asthma: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Asthma is considered to be a chronic inflammatory disorder of the airways. Probiotics are living microorganisms that are found in the human gut and have protective effects against a wide range of diseases such as allergies. The aim of this study was to investigate the improvement of clinical asthma symptoms and changes in the expression pattern of selective microRNAs in patients with asthma and the changes in IL-4 and IFN-γ plasma levels after receiving probiotics.

MATERIALS AND METHODS

The present study was a randomized, double-blind, placebo-controlled trial that enrolled 40 asthmatic patients. They were treated with probiotics or placebo: 1 capsule/day for 8 weeks. Pulmonary function tests, IL-4 and IFN-γ levels, and expression of microRNAs were assessed at baseline and after treatment.

RESULTS

The results showed that the expression of miR-16, miR146-a and IL-4 levels in patients with asthma after receiving probiotic supplementation was significantly reduced and miR-133b expression was increased. In addition, pulmonary function tests showed a significant improvement in Forced Expiratory Volume in 1 s and Forced Vital Capacity after receiving probiotics.

CONCLUSION

In our study, 8-week treatment with probiotic supplementation led to reduced Th2 cells-associated IL-4 and improved Forced Expiratory Volume and Forced Vital Capacity. It appears probiotics can be used in addition to common asthma treatments.

Role of miRNAs in mediating organophosphate compounds induced toxicity

Organophosphate compounds (OPCs) are a diverse class of chemicals utilized in both industrial and agricultural settings. The exact molecular pathways that OPCs-induced toxicity is caused by are still being investigated, despite the fact that studies on this topic have been ongoing for a long time. As a result, it's important to identify innovative strategies to uncover these processes and further the understanding of the pathways involved in OPCs-induced toxicity. In this context, determining the role of microRNAs (miRs) in the toxicity caused by OPCs should be taken into consideration. Recent research on the regulation function of miRs presents key discoveries to identify any gaps in the toxicity mechanisms of OPCs. As diagnostic indicators for toxicity in people exposed to OPCs, various expression miRs can also be used. The results of experimental and human studies into the expression profiles of miRs in OPCs-induced toxicity have been compiled in this article.

Dysregulated MicroRNAs as Biomarkers or Therapeutic Targets in Cisplatin-Induced Nephrotoxicity: A Systematic Review

The purpose of this systematic review was to map out and summarize scientific evidence on dysregulated microRNAs (miRNAs) that can be possible biomarkers or therapeutic targets for cisplatin nephrotoxicity and have already been tested in humans, animals, or cells. In addition, an in silico analysis of the two miRNAs found to be dysregulated in the majority of studies was performed. A literature search was performed using eight databases for studies published up to 4 July 2021. Two independent reviewers selected the studies and extracted the data; disagreements were resolved by a third and fourth reviewers. A total of 1002 records were identified, of which 30 met the eligibility criteria. All studies were published in English and reported between 2010 and 2021. The main findings were as follows: (a) miR-34a and miR-21 were the main miRNAs identified by the studies as possible biomarkers and therapeutic targets of cisplatin nephrotoxicity; (b) the in silico analysis revealed 124 and 131 different strongly validated targets for miR-34a and miR-21, respectively; and (c) studies in humans remain scarce.

Role of microRNAs in Obesity-Related Kidney Disease

Obesity is a major global health problem and is associated with a significant risk of renal function decline. Obesity-related nephropathy, as one of the complications of obesity, is characterized by a structural and functional damage of the kidney and represents one of the important contributors to the morbidity and mortality worldwide. Despite increasing data linking hyperlipidemia and lipotoxicity to kidney injury, the apprehension of molecular mechanisms leading to a development of kidney damage is scarce. MicroRNAs (miRNAs) are endogenously produced small noncoding RNA molecules with an important function in post-transcriptional regulation of gene expression. miRNAs have been demonstrated to be important regulators of a vast array of physiological and pathological processes in many organs, kidney being one of them. In this review, we present an overview of miRNAs, focusing on their functional role in the pathogenesis of obesity-associated renal pathologies. We explain novel findings regarding miRNA-mediated signaling in obesity-related nephropathies and highlight advantages and future perspectives of the therapeutic application of miRNAs in renal diseases.

Non-coding RNAs in Wilms' tumor: biological function, mechanism, and clinical implications

Non-coding RNAs are involved with maintenance and regulation of physiological mechanisms and are involved in pathological processes, such as cancer. Among the small ncRNAs, miRNAs are the most explored in tumorigenesis, metastasis development, and resistance to chemotherapy. These small molecules of ~ 22 nucleotides are modulated during early renal development, involved in the regulation of gene expression and Wilms' tumor progression. Wilms' tumors are embryonic tumors with few mutations and complex epigenetic dysregulation. In recent years, the small ncRNAs have been explored as potentially related both in physiological development and in the tumorigenesis of several types of cancer. Besides, genes regulated by miRNAs are related to biological pathways as PI3K, Wnt, TGF-β, and Hippo signaling pathways, among others, which may be involved with the underlying mechanisms of resistance to chemotherapy, and in this way, it has emerged as potential targets for cancer therapies, including for Wilms' tumors.

The Connection between MicroRNAs from Visceral Adipose Tissue and Non-Alcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) is one of the most important causes of liver disease worldwide leading the foreground cause of liver transplantation. Recently miRNAs, small non-coding molecules were identified as an important player in the negative translational regulation of many protein-coding genes involved in hepatic metabolism. Visceral adipose tissue was found to take part in lipid and glucose metabolism and to release many inflammatory mediators that may contribute to progression of NAFLD from simple steatosis to Non-Alcoholic SteatoHepatitis. Since visceral adipose tissue enlargement and dysregulated levels of miRNAs were observed in patients with NAFLD, the aim of this paper is to reflect the current knowledge of the role of miRNAs released from visceral adipose tissue and NAFLD.

Prenatal caffeine exposure caused H-type blood vessel-related long bone dysplasia via miR375/CTGF signaling

Caffeine has developmental toxicity. Prenatal caffeine exposure (PCE) caused intrauterine growth retardation (IUGR) and multiple organ dysplasia. This study intended to explore the effect and mechanism of PCE on long bone development in female fetal rats. In vivo, the PCE group pregnant rats were given different concentrations of caffeine during the gestational Day 9-20. The mRNA expression of osteogenesis-related genes were significantly reduced in PCE group. In the PCE group (120 mg/kg·d), the length and primary center of fetal femur were shorter, and accompanied by H-type blood vessel abundance reducing. Meanwhile, connective tissue growth factor (CTGF) expression decreased in the growth plate of the PCE group (120 mg/kg·d). In contrast, the miR375 expression increased. In vitro, caffeine decreased CTGF and increased miR375 expression in fetal growth plate chondrocytes. After co-culture with caffeine-treated chondrocytes, the tube formation ability for the H-type endothelial cells was decreased. Furthermore, CTGF overexpression or miR375 inhibitor reversed caffeine-induced reduction of tube formation ability, and miR375 inhibitor reversed caffeine-induced CTGF expression inhibition. In summary, PCE decreased the expression of CTGF by miR375, ultimately resulting in H-type blood vessel-related long bone dysplasia.

Analysis of microRNA processing machinery gene (DROSHA, DICER1, RAN, and XPO5) variants association with end-stage renal disease

BACKGROUND

MicroRNA (miRNA) processing machinery gene variant was associated with several diseases. We aimed to explore for the first time the association of machinery gene (DROSHA rs10719A/G; DICER1 rs3742330A/G; RAN rs14035C/T; and XPO5 rs11077T/G) variants with the susceptibility and phenotype of end-stage renal disease (ESRD).

METHOD

A total of 281 participants (98 ESRD patients and 183 healthy volunteers) were enrolled. Real-Time TaqMan allelic discrimination assay was applied for the genotyping of the specified variants. Multiple logistic regression models, univariate, multivariate, and principal component analyses were carried out.

RESULTS

Carrying one DICER1 rs3742330*G allele conferred protection against developing ESRD [heterozygote comparison: OR = 0.30, 95% CI = 0.15-0.62, dominant model: OR = 0.35, 95% CI = 0.17-0.70]. Similarly, for XPO5 rs11077T/G, homozygote and heterozygote carriers of G variant were less likely to develop ESRD [homozygote comparison: adjusted OR = 0.23, 95% CI = 0.11-0.50, and heterozygote comparison: OR = 0.50, 95% CI = 0.22-0.92, and allelic model: OR = 0.46, 95% CI = 0.34-0.70]. RAN rs14035*TT subjects were 5 times more likely to develop ESRD while being heterozygote (CT) have twice the risk [homozygote comparison: 5.18, 95% CI = 2.28-11.8, heterozygote comparison: OR = 2.12, 95% CI = 1.10-409]. Subgroup analysis also detected DICER1 rs3742330*A, XPO5 rs11077*T, and RAN rs14035*T as genetic risk determinants for ESRD development in both sex and age categories. Two genotype combinations of DROSHA/DICER1/XPO5/RAN were associated with increased susceptibility to ESRD [A-A-T-T: OR = 9.49, 95%CI = 2.48-36.31 (P = .001) and G-A-T-T: OR = 5.92, 95%CI = 1.77-19.83 (P = .004), respectively].

CONCLUSION

Variants and combined genotypes of DICER1 rs3742330, XPO5 rs11077, and RAN rs14035 might be associated with ESRD development in the study population. Integrating molecular analysis in ESRD risk stratification is warranted.

Let-7c-5p Is Involved in Chronic Kidney Disease by Targeting TGF-β Signaling

The purpose of the present study was to investigate the expressions of hsa-let-7c-5p and TGF-β signaling-related molecules and their correlations with clinical characteristics in chronic kidney disease (CKD). Twenty-three biopsy specimens of CKD patients and 20 negative control tissues were selected. Quantitative real-time PCR (qPCR) was used for the detection of hsa-let-7c-5p, transforming growth factor β (TGF-β) and TGF-β receptor type 1 (TGF-βR1) expression levels. Target gene of hsa-let-7c-5p was verified by dual-luciferase reporter assay. A significant decrease of hsa-let-7c-5p expression in CKD tissue was found, compared with that of normal renal tissues (p < 0.01). Expression levels of TGF-β in CKD were increased, compared with that of normal kidney tissue (p < 0.001). The difference in the expression of TGF-β R1 between CKD tissues and normal renal tissues was not significant (p > 0.05). A negative correlation was found between the expression of TGF-β and renal tissue hsa-let-7c-5p levels. Furthermore, hsa-let-7c-5p was identified to regulate TGF- β1 by directly binding with the 167-173 site in the 3′ untranslated region. Decreased hsa-let-7c-5p levels in CKD patients was found to be associated with disease severity, which shows a negative correlation with proteinuria and creatinine levels, and a positive correlation with estimated glomerular filtration rate (eGFR), while relative TGF-β1 expression had a positive correlation with creatinine level. In summary, changes in hsa-let-7c-5p expression and its target gene TGF-β are associated with the disease status of CKD. Let-7c-5p may contribute to the pathogenesis of renal fibrosis through TGF-β signaling, a potential diagnostic and therapeutic target of the disease.

Cadmium-Induced Renal Cell Toxicity Is Associated With MicroRNA Deregulation

Cadmium is an environmental pollutant well known for its nephrotoxic effects. Nevertheless, mechanisms underlying nephrotoxicity continue to be elucidated. MicroRNAs (miRNAs) have emerged in recent years as modulators of xenobiotic-induced toxicity. In this context, our study aimed at elucidating whether miRNAs are involved in renal proximal tubular toxicity induced by cadmium exposure. We showed that cadmium exposure, in 2 distinct renal proximal tubular cell models (renal proximal tubular epithelial cell [RPTEC]/human telomerase reverse transcriptase [hTERT] and human kidney-2), resulted in cytotoxicity associated with morphological changes, overexpression of renal injury markers, and induction of apoptosis and inflammation processes. Cadmium exposure also resulted in miRNA modulation, including the significant upregulation of 38 miRNAs in RPTEC/hTERT cells. Most of these miRNAs are known to target genes whose coding proteins are involved in oxidative stress, inflammation, and apoptosis, leading to tissue remodeling. In conclusion, this study provides a list of dysregulated miRNAs which may play a role in the pathophysiology of cadmium-induced kidney damages and highlights promising cadmium molecular biomarkers that warrants to be further evaluated.

MicroRNA-96 is a potential tumor repressor by inhibiting NPTX2 in renal cell carcinoma

MicroRNA-96 (miR-96) is a vertebrate conserved microRNA which plays important roles in various cancers including renal cell carcinoma (RCC). However, its function and mechanism in RCC are still unclear. In this study, miR-96 was found to be downregulated in RCC based on The Cancer Genome Atlas datasets analyses, and its target genes, which predicted by TargetScan, were investigated. Among these target genes, neuronal pentraxin 2 (NPTX2) was upregulated more than 15-fold in RCC, and moreover, closely related to patient survival. To validate its targeting of NPTX2 experimentally, reverse transcription polymerase chain reaction, Western blot analysis, and dual-luciferase assays were performed, and results of these assays demonstrated that miR-96 inhibited expression of NPTX2 through a single 3'-untranslated region targeting site. Furthermore, transfection assays in RenCa and 786-O cells showed miR-96 and small interfering RNA of NPTX2 inhibited cell proliferation, migration, and invasion and overexpression of NPTX2 recovered the inhibition of miR-96. In conclusion, the present study reveals a novel regulatory mechanism of miR-96 on NPTX2 expression in RCC, and the potential of miR-96 as a RCC tumor repressor deserves further investigation.

Epigenetic regulation in AKI and kidney repair: mechanisms and therapeutic implications

Acute kidney injury (AKI) is a major public health concern associated with high morbidity and mortality. Despite decades of research, the pathogenesis of AKI remains incompletely understood and effective therapies are lacking. An increasing body of evidence suggests a role for epigenetic regulation in the process of AKI and kidney repair, involving remarkable changes in histone modifications, DNA methylation and the expression of various non-coding RNAs. For instance, increases in levels of histone acetylation seem to protect kidneys from AKI and promote kidney repair. AKI is also associated with changes in genome-wide and gene-specific DNA methylation; however, the role and regulation of DNA methylation in kidney injury and repair remains largely elusive. MicroRNAs have been studied quite extensively in AKI, and a plethora of specific microRNAs have been implicated in the pathogenesis of AKI. Emerging research suggests potential for microRNAs as novel diagnostic biomarkers of AKI. Further investigation into these epigenetic mechanisms will not only generate novel insights into the mechanisms of AKI and kidney repair but also might lead to new strategies for the diagnosis and therapy of this disease.

Can microRNA profiles predict corticosteroid responsiveness in childhood nephrotic syndrome? A study protocol

INTRODUCTION

In last few years, several studies have revealed the remarkable stability of extracellular microRNAs (miRNAs) circulating in the blood or excreted in the urine and underscored their key importance as biomarkers of certain diseases. Since miRNA in urinary sediment is relatively stable and easily quantified, it has the potential to be developed as a biomarker for disease diagnosis and monitoring. Identification of serum and urinary levels of certain miRNAs may assist in the diagnosis and assessment of disease activity in patients with nephrotic syndrome (NS). The global expression profile of miRNAs in childhood NS in Indian population remains unknown. Hence, further research is warranted in this area. This study seeks to prospectively evaluate whether a multipronged multiomics approach concentrating on microRNA expression profiles in children with NS vis-a-vis normal healthy children is discriminant enough to predict steroid responsiveness in childhood NS.

METHODS AND ANALYSIS

In this prospective multicentric cohort study, subjects will be recruited from general paediatric and paediatric nephrology outpatient departments (OPDs) in tertiary care level referral hospitals. Age-matched and sex-matched healthy individuals with normal renal function (as assessed by normal serum creatinine and normal ultrasound of kidneys, ureter and bladder) in 1:1 ratio between study and control groups will be recruited from among the healthy siblings of children presenting to the OPDs. Differential microRNA expression profiles in urine and serum samples of children with steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS) with healthy children will be compared in a two-phased manner: a biomarker discovery phase involving pooled samples across SSNS, SRNS and healthy siblings analysed in triplicate using next-generation sequencing, slide microarray and quantitative reverse transcriptase PCR (qRT-PCR) arrays covering human miRNome followed by a validation phase with customised qRT-PCR primers based on the concordance in the discovery phase differential expression profiles and bioinformatics analysis.

ETHICS AND DISSEMINATION

The study is funded after dueInstitutional Ethics Committee (IEC) clearance, and results will be available as open access.

Identification of candidate microRNA biomarkers in diabetic nephropathy: a meta-analysis of profiling studies

AIMS

The aim was to perform a meta-analysis on the miRNA expression profiling studies in diabetic nephropathy (DN) to identify candidate diagnostic biomarkers.

METHODS

A comprehensive literature search was done in several databases and 53 DN miRNA expression studies were selected. To identify significant DN-miR meta-signatures, two meta-analysis methods were employed: vote-counting strategy and the robust rank aggregation method. The targets of DN-miRs were obtained and a gene set enrichment analysis was carried out to identify the pathways most strongly affected by dysregulation of these miRNAs.

RESULTS

We identified a significant miRNA meta-signature common to both meta-analysis approaches of three up-regulated (miR-21-5p, miR-146a-5p, miR-10a-5p) and two down-regulated (miR-25-3p and miR-26a-5p) miRNAs. Besides that, subgroup analyses divided and compared the differentially expressed miRNAs according to species (human and animal), types of diabetes (T1DN and T2DN) and tissue types (kidney, blood and urine). Enrichment analysis confirmed that DN-miRs supportively target functionally related genes in signaling and community pathways in DN.

CONCLUSION

Five highly significant and consistently dysregulated miRNAs were identified, and future studies should focus on discovering their potential effect on DN and their clinical value as DN biomarkers and therapeutic mediators.

MicroRNA-497 suppresses renal cell carcinoma by targeting VEGFR-2 in ACHN cells

Abnormal expression of miRNAs contributed to cancers through regulation of proliferation, apoptosis and drug resistance of cancer cells. The present study was designed to investigate the effect of miR-497 on renal cell carcinoma (RCC) and its possible mechanism. Forty paired clear cell RCC (ccRCC) tissues and adjacent normal kidney tissues were obtained from patients, who were not treated by chemotherapy or radiotherapy. RT-PCR was performed to detect expression of miR-497 in the ccRCC tissues. Effects of miR-497 on cell viability, apoptosis, migration and invasion were detected in ACHN cells. Western blotting (WB) was employed to detect the downstream targets of miR-497. We found that miR-497 in ccRCC tissues was decreased. We treated ACHN cells with miR-497 mimics and inhibitors in vitro and found that miR-497 inhibited viability, migration and invasion of ACHN cells. miR-497 promoted ACHN cells’ apoptosis. VEGFR-2 was predicted as a possible target of miR-497. Luciferase reporter assay proved that miR-497 suppressed VEGFR-2 directly by binding to its 3′-UTR. Further studies showed that miR-497 influenced the MEK/ERK and p38 MAPK signalling pathways. Our findings demonstrated that miR-497 could suppress RCC by targeting VEGFR-2.

c-Myc modulates glucose metabolism via regulation of miR-184/PKM2 pathway in clear-cell renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most malignant tumors worldwide. Among all subtypes of RCC, clear-cell RCC (ccRCC) is the most common and aggressive one. The difficulty in overcoming resistance of traditional treatment is a threat for ccRCC therapies. Therefore, to understand the mechanism that underlies ccRCC progression is critical for new drug development. In the present study, we identified that miR-184 could be downregulated by c-Myc, which is different from the standard opinion that c-Myc is a target of miR-184. Overexpression of pre-miR-184 changed the metabolic and proliferation features of ccRCC cells by reducing cell glucose consumption, lactate production and cell proliferation. Further analysis by computer bioinformatics revealed that PKM2 is a target of miR-184. Both PKM2 mRNA and protein were significantly affected by addition of miR-184. Importantly, the PKM2 expression level was indeed increased in ccRCC samples, which is totally reverse compared to the decreased miR-184 expression level. Interestingly, we found that when PKM2 was knocked down in ccRCC cells, the rapid proliferation, high glucose consumption and high lactate production were all clearly inhibited, which indicates metabolic reprogramming and cancer progression blocking the in ccRCC cells. Our findings shed new light on ccRCC molecular study and provide a new and solid basis for developing ccRCC therapy.

MicroRNA-195 targets VEGFR2 and has a tumor suppressive role in ACHN cells via PI3K/Akt and Raf/MEK/ERK signaling pathways

Increasing evidence indicates that dysregulation of miR-195 may contribute to the occurrence and development of multiple types of human malignancies. However, the function and the mechanism of miR-195 in clear cell renal cell carcinoma (ccRCC) are still not fully understood. In the present study, we used qRT-PCR to detect the expression of miR-195 in ccRCC tissues and normal kidney tissues. MTT assay was performed to detect the cell viability of miR-195. Migration and invasion were evaluated by Transwell migration and Matrigel invasion assays, respectively. Additionally, apoptosis levels were evaluated using TUNEL assays, and signaling pathway changes were determined by western blot analysis. We observed that miR-195 was downregulated in clear cell renal cell carcinoma samples compared with normal renal samples. We identified that overexpression of miR-195 inhibited ACHN cell viability, migration, invasion, and it also induced cell apoptosis by targeting VEGFR2 via PI3K/Akt and Raf/MEK/ERK signaling pathways. These findings indicate that miR-195 has a tumor suppressive role in ACHN cells and miR-195 may be a promising candidate target for prevention and treatment of renal cell carcinoma.

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.

Mesenchymal Stem Cells Deliver Exogenous MicroRNA-let7c via Exosomes to Attenuate Renal Fibrosis

The advancement of microRNA (miRNA) therapies has been hampered by difficulties in delivering miRNA to the injured kidney in a robust and sustainable manner. Using bioluminescence imaging in mice with unilateral ureteral obstruction (UUO), we report that mesenchymal stem cells (MSCs), engineered to overexpress miRNA-let7c (miR-let7c-MSCs), selectively homed to damaged kidneys and upregulated miR-let7c gene expression, compared with nontargeting control (NTC)-MSCs. miR-let7c-MSC therapy attenuated kidney injury and significantly downregulated collagen IVα1, metalloproteinase-9, transforming growth factor (TGF)-β1, and TGF-β type 1 receptor (TGF-βR1) in UUO kidneys, compared with controls. In vitro analysis confirmed that the transfer of miR-let7c from miR-let7c-MSCs occurred via secreted exosomal uptake, visualized in NRK52E cells using cyc3-labeled pre-miRNA-transfected MSCs with/without the exosomal inhibitor, GW4869. The upregulated expression of fibrotic genes in NRK52E cells induced by TGF-β1 was repressed following the addition of isolated exosomes or indirect coculture of miR-let7c-MSCs, compared with NTC-MSCs. Furthermore, the cotransfection of NRK52E cells using the 3'UTR of TGF-βR1 confirmed that miR-let7c attenuates TGF-β1-driven TGF-βR1 gene expression. Taken together, the effective antifibrotic function of engineered MSCs is able to selectively transfer miR-let7c to damaged kidney cells and will pave the way for the use of MSCs for therapeutic delivery of miRNA targeted at kidney disease.

Detection of Drug-Induced Acute Kidney Injury in Humans Using Urinary KIM-1, miR-21, -200c, and -423

Drug-induced acute kidney injury (AKI) is often encountered in hospitalized patients. Although serum creatinine (SCr) is still routinely used for assessing AKI, it is known to be insensitive and nonspecific. Therefore, our objective was to evaluate kidney injury molecule 1 (KIM-1) in conjunction with microRNA (miR)-21, -200c, and -423 as urinary biomarkers for drug-induced AKI in humans. In a cross-sectional cohort of patients (n = 135) with acetaminophen (APAP) overdose, all 4 biomarkers were significantly (P < .004) higher not only in APAP-overdosed (OD) patients with AKI (based on SCr increase) but also in APAP-OD patients without clinical diagnosis of AKI compared with healthy volunteers. In a longitudinal cohort of patients with malignant mesothelioma receiving intraoperative cisplatin (Cp) therapy (n = 108) the 4 biomarkers increased significantly (P < .0014) over time after Cp administration, but could not be used to distinguish patients with or without AKI. Evidence for human proximal tubular epithelial cells (HPTECs) being the source of miRNAs in urine was obtained first, by in situ hybridization based confirmation of increase in miR-21 expression in the kidney sections of AKI patients and second, by increased levels of miR-21, -200c, and -423 in the medium of cultured HPTECs treated with Cp and 4-aminophenol (APAP degradation product). Target prediction analysis revealed 1102 mRNA targets of miR-21, -200c, and -423 that are associated with pathways perturbed in diverse pathological kidney conditions. In summary, we report noninvasive detection of AKI in humans by combining the sensitivity of KIM-1 along with mechanistic potentials of miR-21, -200c, and -423.

A microRNA isolation method from clinical samples

INTRODUCTION

microRNAs (miRNAs) are considered to be novel molecular biomakers that could be exploited in the diagnosis and treatment of different diseases. The present study aimed to develop an efficient miRNA isolation method from different clinical specimens.

METHODS

Total RNAs were isolated by Trizol reagent followed by precipitation of the large RNAs with potassium acetate (KCH3COOH), polyethylene glycol (PEG) 4000 and 6000, and lithium chloride (LiCl). Then, small RNAs were enriched and recovered from the supernatants by applying a combination of LiCl and ethanol. The efficiency of the method was evaluated through the quality, quantity, and integrity of the recovered RNAs using the A260/280 absorbance ratio, reverse transcription PCR (RT-PCR), and quantitative real-time PCR (q-PCR).

RESULTS

Comparison of different RNA isolation methods based on the precipitation of DNA and large RNAs, high miRNA recovery and PCR efficiency revealed that applying potassium acetate with final precipitation of small RNAs using 2.5 M LiCl plus ethanol can provide high yield and quality small RNAs that can be exploited for clinical purposes.

CONCLUSION

The current isolation method can be applied for most clinical samples including cells, formalin-fixed and paraffin-embedded (FFPE) tissues and even body fluids with a wide applicability in molecular biology investigations.

Global miRNA expression is temporally correlated with acute kidney injury in mice

MicroRNAs (miRNAs) are negative regulators of gene expression and protein abundance. Current evidence shows an association of miRNAs with acute kidney injury (AKI) leading to substantially increased morbidity and mortality. Here, we investigated whether miRNAs are inductive regulators responsible for the pathological development of AKI. Microarray analysis was used to detect temporal changes in global miRNA expression within 48 h after AKI in mice. Results indicated that global miRNA expression gradually increased over 24 h from ischemia reperfusion injury after 24 h, and then decreased from 24 h to 48 h. A similar trend was observed for the index of tubulointerstitial injury and the level of serum creatinine, and there was a significant correlation between the level of total miRNA expression and the level of serum creatinine (p < 0.05). This expression-phenotype correlation was validated by quantitative reverse transcription PCR on individual miRNAs, including miR-18a, -134, -182, -210 and -214. Increased global miRNA expression may lead to widespread translational repression and reduced cellular activity. Furthermore, significant inflammatory cytokine release and peritubular capillary loss were observed, suggesting that the initiation of systematic destruction programs was due to AKI. Our findings provide new understanding of the dominant role of miRNAs in promoting the pathological development of AKI.

The Role of MicroRNAs in Kidney Disease

MicroRNAs (miRNAs) are short noncoding RNAs that regulate pathophysiological processes that suppress gene expression by binding to messenger RNAs. These biomolecules can be used to study gene regulation and protein expression, which will allow better understanding of many biological processes such as cell cycle progression and apoptosis that control the fate of cells. Several pathways have also been implicated to be involved in kidney diseases such as Transforming Growth Factor-β, Mitogen-Activated Protein Kinase signaling, and Wnt signaling pathways. The discovery of miRNAs has provided new insights into kidney pathologies and may provide new innovative and effective therapeutic strategies. Research has demonstrated the role of miRNAs in a variety of kidney diseases including renal cell carcinoma, diabetic nephropathy, nephritic syndrome, renal fibrosis, lupus nephritis and acute pyelonephritis. MiRNAs are implicated as playing a role in these diseases due to their role in apoptosis, cell proliferation, differentiation and development. As miRNAs have been detected in a stable condition in different biological fluids, they have the potential to be tools to study the pathogenesis of human diseases with a great potential to be used in disease prognosis and diagnosis. The purpose of this review is to examine the role of miRNA in kidney disease.

[MicroRNAs in kidney fibrosis]

Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function with accumulation of extracellular matrix components in the renal parenchyma. The molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the profibrotic role of several microRNAs (miRNAs) has been described in kidney fibrosis. MiRNAs are a new class of, small non-coding RNAs of about 20 nucleotides that act as gene expression negative regulators at the post-transcriptional level. Seminal studies have highlighted the potential importance of miRNA as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review summarizes recent scientific advances on the role played by miRNAs in kidney fibrogenesis and discusses potential clinical applications as well as future research directions.

Role of microRNA machinery in kidney fibrosis

MicroRNAs (miRNAs) are small non-coding RNAs that are critical regulators of gene expression at the post-transcriptional level. The miRNAs constitute an abundant class of RNAs conserved from plants to animals and, as such, play key roles in diverse biological processes, including inflammation, development, differentiation and apoptosis. More recently, it has become apparent that changes in miRNA expression contribute to a wide spectrum of human pathologies, including heart and kidney disease, organ developmental abnormalities and neuronal degeneration. Moreover, inflammation and the development of kidney fibrosis is accompanied by changes in miRNA expression. This review summarizes the emerging field deciphering the complex connections between human miRNA biology and different aspects of kidney injury, focusing on kidney fibrosis. The miRNA-regulated fibrosis is discussed based on the classification of pivotal mechanisms, notably involving the transforming growth factor-β1 signalling pathway. In addition, the challenge of miRNA delivery vehicles as mechanisms of cellular transfer are reviewed, as is the use of miRNA as a potential biomarker for disease.

Expression Profiles and Clinical Significance of MicroRNAs in Papillary Renal Cell Carcinoma: A STROBE-Compliant Observational Study

Papillary renal cell carcinoma (pRCC) is the second most prevalent subtype of kidney cancers. In the current study, we analyzed the global microRNA (miRNA) expression profiles in pRCC, with the aim to evaluate the relationship of miRNA expression with the progression and prognosis of pRCC.A total of 163 treatment-naïve primary pRCC patients were identified from the Cancer Genome Atlas dataset and included in this retrospective observational study. The miRNA expression profiles were graded by tumor-node-metastasis information, and compared between histologic subtypes. Furthermore, the training-validation approach was applied to identify miRNAs of prognostic values, with the aid of Kaplan-Meier survival, and univariate and multivariate Cox regression analyses. Finally, the online DAVID (Database for Annotation, Visualization, and Integrated Discover) program was applied for the pathway enrichment analysis with the target genes of prognosis-associated miRNAs, which were predicted by 3 computational algorithms (PicTar, TargetScan, and Miranda).In the progression-related miRNA profiles, 26 miRNAs were selected for pathologic stage, 28 for pathologic T, 16 for lymph node status, 3 for metastasis status, and 32 for histologic types, respectively. In the training stage, the expression levels of 12 miRNAs (mir-134, mir-379, mir-127, mir-452, mir-199a, mir-200c, mir-141, mir-3074, mir-1468, mir-181c, mir-1180, and mir-34a) were significantly associated with patient survival, whereas mir-200c, mir-127, mir-34a, and mir-181c were identified by multivariate Cox regression analyses as potential independent prognostic factors in pRCC. Subsequently, mir-200c, mir-127, and mir-34a were confirmed to be significantly correlated with patient survival in the validation stage. Finally, target gene prediction analysis identified a total of 113 target genes for mir-200c, 37 for mir-127, and 180 for mir-34a, which further generated 15 molecular pathways.Our results identified the specific miRNAs associated with the progression and aggressiveness of pRCC, and 3 miRNAs (mir-200c, mir-127, and mir-34a) as promising prognostic factors of pRCC.

The ureteric bud epithelium: morphogenesis and roles in metanephric kidney patterning

The mammalian metanephric kidney is composed of two epithelial components, the collecting duct system and the nephron epithelium, that differentiate from two different tissues -the ureteric bud epithelium and the nephron progenitors, respectively-of intermediate mesoderm origin. The collecting duct system is generated through reiterative ureteric bud branching morphogenesis, whereas the nephron epithelium is formed in a process termed nephrogenesis, which is initiated with the mesenchymal-epithelial transition of the nephron progenitors. Ureteric bud branching morphogenesis is regulated by nephron progenitors, and in return, the ureteric bud epithelium regulates nephrogenesis. The metanephric kidney is physiologically divided along the corticomedullary axis into subcompartments that are enriched with specific segments of these two epithelial structures. Here, we provide an overview of the major molecular and cellular processes underlying the morphogenesis and patterning of the ureteric bud epithelium and its roles in the cortico-medullary patterning of the metanephric kidney.

miRNAs in urine: a mirror image of kidney disease?

miRNAs are short non-coding RNAs that control post-transcriptional regulation of gene expression. They are found ubiquitously in tissue and body fluids and participate in the pathogenesis of many diseases. Due to these characteristics and their stability, miRNAs could serve as biomarkers of different pathologies of the kidney. Urine is a non-invasive reservoir of molecules, especially indicative of the urinary system. In this review, we focus on urinary miRNAs and their potential to serve as biomarkers in kidney disease. Past studies show that urinary miRNAs correlate with renal dysfunctions and with processes involved in the pathophysiology. However, these studies also stress the need for future research focusing on large-scale studies to confirm the usability of urinary miRNAs as diagnostic and/or prognostic markers of different kidney diseases in clinical practice.

The development of Wilms tumor: from WT1 and microRNA to animal models

Wilms tumor recapitulates the development of the kidney and represents a unique opportunity to understand the relationship between normal and tumor development. This has been illustrated by the findings that mutations of Wnt/β-catenin pathway-related WT1, β-catenin, and WTX together account for about one-third of Wilms tumor cases. While intense efforts are being made to explore the genetic basis of the other two-thirds of tumor cases, it is worth noting that, epigenetic changes, particularly the loss of imprinting of the DNA region encoding the major fetal growth factor IGF2, which results in its biallelic over-expression, are closely associated with the development of many Wilms tumors. Recent investigations also revealed that mutations of Drosha and Dicer, the RNases required for miRNA generation, and Dis3L2, the 3'-5' exonuclease that normally degrades miRNAs and mRNAs, could cause predisposition to Wilms tumors, demonstrating that miRNA can play a pivotal role in Wilms tumor development. Interestingly, Lin28, a direct target of miRNA let-7 and potent regulator of stem cell self-renewal and differentiation, is significantly elevated in some Wilms tumors, and enforced expression of Lin28 during kidney development could induce Wilms tumor. With the success in establishing mice nephroblastoma models through over-expressing IGF2 and deleting WT1, and advances in understanding the ENU-induced rat model, we are now able to explore the molecular and cellular mechanisms induced by these genetic, epigenetic, and miRNA alterations in animal models to understand the development of Wilms tumor. These animal models may also serve as valuable systems to assess new treatment targets and strategies for Wilms tumor.

The role of viral and host microRNAs in the Aujeszky's disease virus during the infection process

Porcine production is a primary market in the world economy. Controlling swine diseases in the farm is essential in order to achieve the sector necessities. Aujeszky’s disease is a viral condition affecting pigs and is endemic in many countries of the world, causing important economic losses in the swine industry. microRNAs (miRNAs) are non-coding RNAs which modulates gene expression in animals, plants and viruses. With the aim of understanding miRNA roles during the Aujeszky’s disease virus [ADV] (also known as suid herpesvirus type 1 [SuHV-1]) infection, the expression profiles of host and viral miRNAs were determined through deep sequencing in SuHV-1 infected porcine cell line (PK-15) and in an animal experimental SuHV-1 infection with virulent (NIA-3) and attenuated (Begonia) strains. In the in vivo approach miR-206, miR-133a, miR-133b and miR-378 presented differential expression between virus strains infection. In the in vitro approach, most miRNAs were down-regulated in infected groups. miR-92a and miR-92b-3p were up-regulated in Begonia infected samples. Functional analysis of all this over expressed miRNAs during the infection revealed their association in pathways related to viral infection processes and immune response. Furthermore, 8 viral miRNAs were detected by stem loop RT-qPCR in both in vitro and in vivo approaches, presenting a gene regulatory network affecting 59 viral genes. Most described viral miRNAs were related to Large Latency Transcript (LLT) and to viral transcription activators EP0 and IE180, and also to regulatory genes regarding their important roles in the host – pathogen interaction during viral infection.

MicroRNAs in Diabetic Kidney Disease

Rapid growth of diabetes and diabetic kidney disease exerts a great burden on society. Owing to the lack of effective treatments for diabetic kidney disease, treatment relies on drugs that either reduces its progression or involve renal replacement therapies, such as dialysis and kidney transplantation. It is urgent to search for biomarkers for early diagnosis and effective therapy. The discovery of microRNAs had lead to a new era of post-transcriptional regulators of gene expression. Studies from cells, experimental animal models and patients under diabetic conditions demonstrate that expression patterns of microRNAs are altered during the progression of diabetic kidney disease. Functional studies indicate that the ability of microRNAs to bind 3' untranslated region of messenger RNA not only shows their capability to regulate expression of target genes, but also their therapeutic potential to diabetic kidney disease. The presence of microRNAs in plasma, serum, and urine has been shown to be possible biomarkers in diabetic kidney disease. Therefore, identification of the pathogenic role of microRNAs possesses an important clinical impact in terms of prevention and treatment of progression in diabetic kidney disease because it allows us to design novel and specific therapies and diagnostic tools for diabetic kidney disease.