Differentially expressed long non‑coding RNAs and mRNAs in patients with IgA nephropathy

A Study on Associations of Long Noncoding RNA HOTAIR Polymorphisms With Genetic Susceptibility to Chronic Kidney Disease

BACKGROUND

The importance of long noncoding RNAs (lncRNAs) in various biological processes has been increasingly recognized in recent years. This study investigated how gene polymorphism in HOX transcript antisense RNA (HOTAIR) lncRNA affects the predisposition to chronic kidney disease (CKD).

METHODS

This study comprised 150 patients with CKD and 150 healthy controls. A PCR-RFLP and ARMS-PCR techniques were used for genotyping the five target polymorphisms.

RESULTS

According to our findings, rs4759314 confers strong protection against CKD in allelic, dominant, and codominant heterozygote genetic patterns. Furthermore, rs3816153 decreased CKD risk by 78% when TT versus GG, 55% when GG+GT versus TT, and 74% when GT versus TT+GG. In contrast, the CC+CT genotype [odds ratio (OR) = 1.66, 95% confidence intervals (CIs) = 1.05-2.63] and the T allele (OR = 1.50, 95% CI = 1.06-2.11) of rs12826786, as well as the TT genotype (OR = 2.52, 95% CI = 1.06-5.98) of rs3816153 markedly increased the risk of CKD in the Iranian population. Although no linkage disequilibrium was found between the studied variants, the Crs12826786Trs920778Grs1899663Grs4759314Grs3816153 haplotype was associated with a decreased risk of CKD by 86% (OR = 0.14, 95% CI = 0.03-0.66).

CONCLUSION

The rs920778 was not correlated with CKD risk, whereas the HOTAIR rs4759314, rs12826786, rs1899663, and rs3816153 polymorphisms affected the risk of CKD in our population. It seems essential to conduct repeated studies across various ethnic groups to explore the link between HOTAIR variants and their impact on the disease outcome.

Deciphering roles of protein post-translational modifications in IgA nephropathy progression and potential therapy

Immunoglobulin A nephropathy (IgAN), one type of glomerulonephritis, displays the accumulation of glycosylated IgA in the mesangium. Studies have demonstrated that both genetics and epigenetics play a pivotal role in the occurrence and progression of IgAN. Post-translational modification (PTM) has been revealed to critically participate in IgAN development and progression because PTM dysregulation results in impaired degradation of proteins that regulate IgAN pathogenesis. A growing number of studies identify that PTMs, including sialylation, o-glycosylation, galactosylation, phosphorylation, ubiquitination and deubiquitination, modulate the initiation and progression of IgAN. Hence, in this review, we discuss the functions and mechanisms of PTMs in regulation of IgAN. Moreover, we outline numerous compounds that govern PTMs and attenuate IgAN progression. Targeting PTMs might be a useful strategy to ameliorate IgAN.

Long noncoding RNA: An emerging diagnostic and therapeutic target in kidney diseases

Long noncoding RNAs (lncRNAs) have critical roles in the development of many diseases including kidney disease. An increasing number of studies have shown that lncRNAs are involved in kidney development and that their dysregulation can result in distinct disease processes, including acute kidney injury, chronic kidney disease, and renal cell carcinoma. Understanding the roles of lncRNAs in kidney disease may provide new diagnostic and therapeutic opportunities in the clinic. This review provides an overview of lncRNA characteristics, and biological function and discusses specific studies that provide insight into the function and potential application of lncRNAs in kidney disease treatment.

The Mission of Long Non-Coding RNAs in Human Adult Renal Stem/Progenitor Cells and Renal Diseases

Long non-coding RNAs (lncRNAs) are a large, heterogeneous class of transcripts and key regulators of gene expression at both the transcriptional and post-transcriptional levels in different cellular contexts and biological processes. Understanding the potential mechanisms of action of lncRNAs and their role in disease onset and development may open up new possibilities for therapeutic approaches in the future. LncRNAs also play an important role in renal pathogenesis. However, little is known about lncRNAs that are expressed in the healthy kidney and that are involved in renal cell homeostasis and development, and even less is known about lncRNAs involved in human adult renal stem/progenitor cells (ARPC) homeostasis. Here we give a thorough overview of the biogenesis, degradation, and functions of lncRNAs and highlight our current understanding of their functional roles in kidney diseases. We also discuss how lncRNAs regulate stem cell biology, focusing finally on their role in human adult renal stem/progenitor cells, in which the lncRNA HOTAIR prevents them from becoming senescent and supports these cells to secrete high quantities of α-Klotho, an anti-aging protein capable of influencing the surrounding tissues and therefore modulating the renal aging.

Long non-coding RNA lnc-CHAF1B-3 promotes renal interstitial fibrosis by regulating EMT-related genes in renal proximal tubular cells

Renal interstitial fibrosis (RIF) is a common pathological manifestation of chronic kidney diseases. Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is considered a major cause of RIF. Although long non-coding RNAs (lncRNAs) are reportedly involved in various pathophysiological processes, the roles and underlying molecular mechanisms of lncRNAs in the progression of RIF are poorly understood. In this study, we investigated the function of lncRNAs in RIF. Microarray assays showed that expression of the lncRNA lnc-CHAF1B-3 (also called claudin 14 antisense RNA 1) was significantly upregulated in human renal proximal tubular cells by both transforming growth factor-β1 (TGF-β1) and hypoxic stimulation, accompanied with increased expression of EMT-related genes. Knockdown of lnc-CHAF1B-3 significantly suppressed TGF-β1-induced upregulated expression of collagen type I alpha 1, cadherin-2, plasminogen activator inhibitor-1, snail family transcriptional repressor I (SNAI1) and SNAI2. Quantitative reverse transcriptase PCR analyses of paraffin-embedded kidney biopsy samples from IgA nephropathy patients revealed lnc-CHAF1B-3 expression was correlated positively with urinary protein levels and correlated negatively with estimated glomerular filtration rate. In situ hybridization demonstrated that lnc-CHAF1B-3 is expressed only in proximal tubules. These findings suggest lnc-CHAF1B-3 affects the progression of RIF by regulating EMT-related signaling. Thus, lnc-CHAF1B-3 is a potential target in the treatment of RIF.

Noncoding RNAs associated with IgA nephropathy

IgA nephropathy (IgAN) is one of the most common glomerulonephritides. The disease is characterized by haematuria, proteinuria, deposition of galactose-deficient IgA1 in the glomerular mesangium and mesangial hypercellularity, further leading to extracellular matrix expansion. Kidney biopsy is the gold standard for IgAN diagnosis. Due to the invasiveness of renal biopsy, there is an unmet need for noninvasive biomarkers to diagnose and estimate the severity of IgAN. Understanding the role of RNA molecules as genetic markers to target diseases may allow developing therapeutic and diagnostic markers. In this review we have focused on intrarenal, extrarenal and extracellular noncoding RNAs involved in the progression of IgAN. This narrative review summarizes the pathogenesis of IgAN along with the correlation of noncoding RNA molecules such as microRNAs, small interfering RNAs, circular RNAs and long non-coding RNAs that play an important role in regulating gene expression, and that represent another type of regulation affecting the expression of specific glycosyltranferases, a key element contributing to the development of IgAN.

Kidney diseases and long non-coding RNAs in the limelight

The most extensively and well-investigated sequences in the human genome are protein-coding genes, while large numbers of non-coding sequences exist in the human body and are even more diverse with more potential roles than coding sequences. With the unveiling of non-coding RNA research, long-stranded non-coding RNAs (lncRNAs), a class of transcripts >200 nucleotides in length primarily expressed in the nucleus and rarely in the cytoplasm, have drawn our attention. LncRNAs are involved in various levels of gene regulatory processes, including but not limited to promoter activity, epigenetics, translation and transcription efficiency, and intracellular transport. They are also dysregulated in various pathophysiological processes, especially in diseases and cancers involving genomic imprinting. In recent years, numerous studies have linked lncRNAs to the pathophysiology of various kidney diseases. This review summarizes the molecular mechanisms involved in lncRNAs, their impact on kidney diseases, and associated complications, as well as the value of lncRNAs as emerging biomarkers for the prevention and prognosis of kidney diseases, suggesting their potential as new therapeutic tools.

Non-Coding RNAs in Kidney Diseases: The Long and Short of Them

Recent progress in genomic research has highlighted the genome to be much more transcribed than expected. The formerly so-called junk DNA encodes a miscellaneous group of largely unknown RNA transcripts, which contain the long non-coding RNAs (lncRNAs) family. lncRNAs are instrumental in gene regulation. Moreover, understanding their biological roles in the physiopathology of many diseases, including renal, is a new challenge. lncRNAs regulate the effects of microRNAs (miRNA) on mRNA expression. Understanding the complex crosstalk between lncRNA–miRNA–mRNA is one of the main challenges of modern molecular biology. This review aims to summarize the role of lncRNA on kidney diseases, the molecular mechanisms involved, and their function as emerging prognostic biomarkers for both acute and chronic kidney diseases. Finally, we will also outline new therapeutic opportunities to diminish renal injury by targeting lncRNA with antisense oligonucleotides.

Comprehensive analysis of IgA nephropathy expression profiles: identification of potential biomarkers and therapeutic agents

Background

IgA nephropathy (IgAN) is a kidney disease recognized by the presence of IgA antibody depositions in kidneys. The underlying mechanisms of this complicated disease are remained to be explored and still, there is an urgent need for the discovery of noninvasive biomarkers for its diagnosis. In this investigation, an integrative approach was applied to mRNA and miRNA expression profiles in PBMCs to discover a gene signature and novel potential targets/biomarkers in IgAN.

Methods

Datasets were selected from gene expression omnibus database. After quality control checking, two datasets were analyzed by Limma to identify differentially expressed genes/miRNAs (DEGs and DEmiRs). Following identification of DEmiR-target genes and data integration, intersecting mRNAs were subjected to different bioinformatic analyses. The intersecting mRNAs, DEmiRs, related transcription factors (from TRRUST database), and long-non coding RNAs (from LncTarD database) were used for the construction of a multilayer regulatory network via Cytoscape.

Result

“GSE25590” (miRNA) and “GSE73953” (mRNA) datasets were analyzed and after integration, 628 intersecting mRNAs were identified. The mRNAs were mainly associated with “Innate immune system”, “Apoptosis”, as well as “NGF signaling” pathways. A multilayer regulatory network was constructed and several hub-DEGs (Tp53, STAT3, Jun, etc.), DEmiRs (miR-124, let-7b, etc.), TFs (NF-kB, etc.), and lncRNAs (HOTAIR, etc.) were introduced as potential factors in the pathogenesis of IgAN.

Conclusion

Integration of two different expression datasets and construction of a multilayer regulatory network not only provided a deeper insight into the pathogenesis of IgAN, but also introduced several key molecules as potential therapeutic target/non-invasive biomarkers.

Long Noncoding RNA PRNCR1 Reduces Renal Epithelial Cell Apoptosis in Cisplatin-Induced AKI by Regulating miR-182-5p/EZH1

BACKGROUND/AIMS

This study was designed to examine the role of long noncoding RNA PRNCR1 in cisplatin-induced acute kidney injury (AKI) in vitro and in vivo.

METHODS

The expression levels of PRNCR1 and miR-182-5p in cisplatin-induced AKI mice were examined. HK-2 cells were treated with cisplatin to induce cell damage. Then, the effects of PRNCR1 and miR-182-5p on cisplatin-stimulated HK-2 cell viability and apoptosis were detected by the CCK-8 and annexin V-FITC/PI method. Target genes of PRNCR1 and miR-182-5p were analyzed by bioinformatics analysis and luciferase.

RESULTS

The expression level of PRNCR1 was significantly reduced in cisplatin-induced AKI mice. In addition, overexpression of PRNCR1 attenuated the damage of cisplatin to HK-2. The expression level of miR-182-5p was significantly raised in cisplatin-induced AKI mice. MiR-182-5p was negatively regulated by PRNCR1 and leaded to an upregulation of EZH1 expression. Overexpression of PRNCR1 attenuated cisplatin-induced apoptosis by downregulating the miR-182-5p/EZH1 axis.

CONCLUSION

LncPRNCR1 reduced the apoptosis of renal epithelial cells induced by cisplatin by modulating miR-182-5p/EZH1.

Long noncoding RNA Mirt2 prohibits lipopolysaccharide-evoked HK-2 cell injury via modulation of microRNA-126

Long noncoding RNA myocardial infarction-associated transcript 2 (lncRNA Mirt2) is a burgeoning lncRNA, its anti-inflammatory capacity has been testified. Nonetheless, the functions of Mirt2 in immunoglobulin A nephropathy are unexplored. We tried to impart the influences of Mirt2 in lipopolysaccharide (LPS)-evoked HK-2 cells damage. HK-2 cells were manipulated with 10 ng/ml LPS, next cell viability, apoptosis, reactive oxygen species (ROS) generation, pro-inflammatory factors and Mirt2 expression were evaluated. After pc-Mirt2 vector transfection, the aforementioned trials were performed. Meanwhile, real-time quantitative polymerase chain reaction (PCR) experiment was used to detect miR-126 expression. Subsequently, functions of miR-126 in LPS-treated HK-2 cells were further delved after transfection with miR-126 mimic. Western blot was used to evaluate NF-κB pathway. The data showed that LPS invoked HK-2 cells inflammatory damage via the suppression of cell viability and the acceleration of apoptosis, ROS level, and IL-1β and IL-6 secretion. LPS inhibited Mirt2 expression and overexpression of Mirt2 mitigated LPS-caused inflammatory damage in HK-2 cells. Additionally, overexpression of Mirt2 repressed miR-126 expression in LPS-stimulated cells. Meanwhile the anti-inflammatory effect of Mirt2 was inverted by upregulating miR-126 expression. Besides, overexpressed Mirt2 retarded LPS-activated NF-κB pathway via repressing miR-126. The research certified the anti-inflammatory impacts of Mirt2 on LPS-impaired HK-2 cells.

Genetic variants of the MIR31HG gene are related to a risk of IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Previous studies reveal that genetic factors play a crucial role in IgAN progression. This study was conducted to investigate the association between MIR31HG variants and IgAN risk. A total of 836 subjects were recruited to detect the relationship of MIR31HG variants with IgAN susceptibility. Odds ratios (OR) and 95% confidence intervals (CI) were computed to evaluate the associations. Multifactor dimensionality reduction was performed to analyze the SNP-SNP interaction with IgAN risk. Our study showed that rs1332184 and rs55683539 significantly related to an increased risk of IgAN (OR 1.34, p = 0.041; OR 1.39, p = 0.025). Stratified analyses indicated rs72703442, rs55683539, and rs10965064 exhibited strongly enhanced risk of IgAN in age ≤ 35 years (OR 1.55, p = 0.023; OR 1.60, p = 0.012; OR 1.46, p = 0.037). Besides, we found rs1332184, rs55683539 and rs2181559 significantly increased the susceptibility of IgAN in males (OR 1.71, p = 0.003; OR 1.44, p = 0.042; OR 1.60, p = 0.010). We also observed that rs1332184 could enhance IgAN risk for Lee's grade ≥ III (OR 1.39, p = 0.045). Rs55683539 significantly increased a risk of IgAN (OR 1.58, p = 0.027), while rs2025327 had a lower risk of IgAN in Lee's grade < III (OR 0.46, p = 0.007). Interestingly, we found rs72703442 polymorphism was related to hemoglobin (p = 0.043), and rs10965064 was associated with Urine red blood cell (p = 0.040). Our study proposed that MIR31HG polymorphisms associate with susceptibility to IgAN in Chinese population.

Identification of differentially expressed circulating exosomal lncRNAs in IgA nephropathy patients

Background

Although immunoglobulin A nephropathy (IgAN) is one of the foremost primary glomerular disease, treatment of IgAN is still in infancy. Non-invasive biomarkers are urgently needed for IgAN diagnosis. We investigate the difference in expression profiles of exosomal long non-coding-RNAs (lncRNAs) in plasma from IgAN patients compared with their healthy first-degree relatives, which may reveal novel non-invasive IgAN biomarkers.

Methods

We isolated exosomes from the plasma of both IgAN patients and their healthy first-degree relatives. High-throughput RNA sequencing and real-time quantitative polymerase chain reaction (qRT-PCR) was used to validate lncRNA expression profiles. Pathway enrichment analysis was used to predict their nearest protein-coding genes.

Results

lncRNA-G21551 was significantly down-regulated in IgAN patients. Interestingly, the nearest protein-coding gene of lncRNA-G21551 was found to be encoding the low affinity receptor of the Fc segment of immunoglobulin G (FCGR3B).

Conclusions

Exosomal lncRNA-G21551, with FCGR3B as the nearest protein-coding gene, was down-regulated in IgAN patients, indicating its potential to serve as a non-invasive biomarker for IgAN.

Long Non-Coding RNAs in Kidney Disease

Non-coding RNA species contribute more than 90% of all transcripts and have gained increasing attention in the last decade. One of the most recent members of this group are long non-coding RNAs (lncRNAs) which are characterized by a length of more than 200 nucleotides and a lack of coding potential. However, in contrast to this simple definition, lncRNAs are heterogenous regarding their molecular function—including the modulation of small RNA and protein function, guidance of epigenetic modifications and a role as enhancer RNAs. Furthermore, they show a highly tissue-specific expression pattern. These aspects already point towards an important role in cellular biology and imply lncRNAs as players in development, health and disease. This view has been confirmed by numerous publications from different fields in the last years and has raised the question as to whether lncRNAs may be future therapeutic targets in human disease. Here, we provide a concise overview of the current knowledge on lncRNAs in both glomerular and tubulointerstitial kidney disease.