Long non-coding RNAs: An essential emerging field in kidney pathogenesis

LncRNA H19 accelerates renal fibrosis by negatively regulating the let-7b-5p/TGF-βR1/COL1A1 axis

BACKGROUND

Transforming growth factor-beta1 (TGF-β1)-mediated renal fibrosis is a critical pathological process of chronic kidney disease worsening to end-stage renal disease. Recent studies have shown that long noncoding RNA H19 (lncRNA H19) is widely involved in the formation and progression of fibrosis in multiple organs. However, its molecular events in renal fibrosis remain to be elucidated.

METHODS

Rats were treated with adenine intragastrically and HK-2 cells were induced by TGF-β1 to construct renal fibrosis models in vivo and in vitro, respectively. Renal histopathological examination was performed using HE and Masson staining. Gene expression levels of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), TGF-β1, fibronectin (Fn), alpha-smooth muscle actin (α-SMA), H19, let-7b-5p, TGF-β receptor 1 (TGF-βR1), and type I collagen (COL1A1) were detected by qRT-PCR. Immunohistochemistry, immunofluorescence, and western blot analysis were used to evaluate the expression of renal fibrosis biomarkers. Dual-luciferase reporter assay was used to verify the presence of binding sites between H19 and let-7b-5p, and between let-7b-5p and TGF-βR1 and COL1A1.

RESULTS

H19 was overexpressed in both in vivo and in vitro renal fibrosis models. H19 knockdown significantly reversed TGF-β1-induced upregulation of fibronectin, COL1A1, and α-SMA and downregulation of E-cadherin in HK-2 cells, accompanied by an increase in let-7b-5p. Let-7b-5p was bound to H19 in HK-2 cells, and its overexpression inhibited TGF-β1-induced HK-2 cell fibrosis. Further experiments determined that let-7b-5p directly targets TGF-βR1 and COL1A1 in HK-2 cells. In addition, inhibition of let-7b-5p reversed the reduction in HK-2 cell fibrosis induced by H19 knockdown. Finally, knockdown of H19 alleviated renal fibrosis in vivo and was associated with regulation of the let-7b-5p/TGF-βR1/COL1A1 axis.

CONCLUSION

Our results indicate that knockdown of H19 inhibits renal tubular epithelial fibrosis by negatively regulating the let-7b-5p/TGF-βR1/COL1A1 axis, which may provide new mechanistic insights into CRF progression.

Complex Pathophysiology of Acute Kidney Injury (AKI) in Aging: Epigenetic Regulation, Matrix Remodeling, and the Healing Effects of H2S

The kidney is an essential excretory organ that works as a filter of toxins and metabolic by-products of the human body and maintains osmotic pressure throughout life. The kidney undergoes several physiological, morphological, and structural changes with age. As life expectancy in humans increases, cell senescence in renal aging is a growing challenge. Identifying age-related kidney disorders and their cause is one of the contemporary public health challenges. While the structural abnormalities to the extracellular matrix (ECM) occur, in part, due to changes in MMPs, EMMPRIN, and Meprin-A, a variety of epigenetic modifiers, such as DNA methylation, histone alterations, changes in small non-coding RNA, and microRNA (miRNA) expressions are proven to play pivotal roles in renal pathology. An aged kidney is vulnerable to acute injury due to ischemia-reperfusion, toxic medications, altered matrix proteins, systemic hemodynamics, etc., non-coding RNA and miRNAs play an important role in renal homeostasis, and alterations of their expressions can be considered as a good marker for AKI. Other epigenetic changes, such as histone modifications and DNA methylation, are also evident in AKI pathophysiology. The endogenous production of gaseous molecule hydrogen sulfide (H2S) was documented in the early 1980s, but its ameliorative effects, especially on kidney injury, still need further research to understand its molecular mode of action in detail. H2S donors heal fibrotic kidney tissues, attenuate oxidative stress, apoptosis, inflammation, and GFR, and also modulate the renin-angiotensin-aldosterone system (RAAS). In this review, we discuss the complex pathophysiological interplay in AKI and its available treatments along with future perspectives. The basic role of H2S in the kidney has been summarized, and recent references and knowledge gaps are also addressed. Finally, the healing effects of H2S in AKI are described with special emphasis on epigenetic regulation and matrix remodeling.

Mechanisms of norcantharidin against renal tubulointerstitial fibrosis

Renal tubulointerstitial fibrosis (RTIF) is a common feature and inevitable consequence of all progressive chronic kidney diseases, leading to end-stage renal failure regardless of the initial cause. Although research over the past few decades has greatly improved our understanding of the pathophysiology of RTIF, until now there has been no specific treatment available that can halt the progression of RTIF. Norcantharidin (NCTD) is a demethylated analogue of cantharidin, a natural compound isolated from 1500 species of medicinal insect, the blister beetle (Mylabris phalerata Pallas), traditionally used for medicinal purposes. Many studies have found that NCTD can attenuate RTIF and has the potential to be an anti-RTIF drug. This article reviews the recent progress of NCTD in the treatment of RTIF, with emphasis on the pharmacological mechanism of NCTD against RTIF.

Renoprotective Potency of Sitagliptin versus Pioglitazone in Type 2 Diabetic Patients: Impact on LncMIAT

Background: Diabetes mellitus (DM) represents one of the most important reasons for chronic kidney diseases due to the high level of blood glucose that destructs blood vessels. Objective: The present study focused on investigating the protective impact of sitagliptin on kidney complication in type 2 diabetes mellitus (T2DM) patients in comparison to pioglitazone to examine which has the superior effect against the nephritic complication of DM. Methods: Eighty adult subjects were classified into four groups: control group, pioglitazone-treated T2DM patients (P group), sitagliptin-treated T2DM patients for less than one year (SL group), and sitagliptin-treated T2DM patients for more than one year (SM group). Blood samples were withdrawn from all subjects for analysis of neutrophil gelatinase-associated lipocalin (NGAL), vanin-1, kidney injury molecule-1 (KIM-1), glyoxalase-1 (Glo-1), methylglyoxal (MG), cystatin-C, and interleukin-18 (IL-18) using competitive ELISA kits. Also, long noncoding myocardial infarction associated transcript (lncMIAT) was measured in whole blood using qRT-PCR. Results: The present study revealed that the lncMIAT expression level was significantly higher in the P group as compared to the SL group, SM group, or healthy control group. Additionally, serum NGAL, vanin-1, KIM-1, Glo-1, MG, and cystatin-C were significantly higher in the P group and SL group as compared to the SM group and healthy control group. Conclusion: Sitagliptin protected the kidney through downregulation of lncMIAT besides amelioration of kidney injury marker levels, which was more preferable than in pioglitazone therapy.

Cross talk between exosomes and pancreatic β-cells in diabetes

Exosomes are a class of extracellular vesicles with a diameter of 50-100 nm secreted by various cells. They are generated through complex intracellular production mechanisms before being secreted to the extracellular environment. Due to their inclusion of proteins, lipids, and nucleic acids, exosomes play an important role in intercellular communication. Pancreatic β-cells play an irreplaceable role in the body's glucose metabolism. Their dysfunction is one of the causes of diabetes. Exosomes of various cells regulate the function of β-cells by regulating autoimmunity, delivering non-coding RNAs, or directly regulating intracellular signal pathways. This communication between β-cells and other cells plays an important role in the pathogenesis and development of diabetes, and has potential for clinical application. This paper reviews the biological sources and functions of exosomes, as well as intercellular crosstalk between β-cells and other cells that is involved in β-cell failure and regeneration.

Hederagenin ameliorates cisplatin-induced acute kidney injury via inhibiting long non-coding RNA A330074k22Rik/Axin2/β-catenin signalling pathway

BACKGROUND

Acute kidney injury (AKI), a kidney disease with high morbidity and mortality, is characterized by a dramatic decline in renal function. Hederagenin (HDG), a pentacyclic triterpenoid saponin isolated from astragalus membranaceus, has been shown to have significant anti-inflammatory effects on various diseases. However, the effects of HDG on renal injury and inflammation in AKI has not been elucidated.

METHODS

In this research, mice model of AKI was established by intraperitoneal injection of cisplatin in vivo, the inflammatory model of renal tubular epithelial cells was established by LPS stimulation in vitro, and HDG was used to intervene in vitro and in vivo models. Transcriptome sequencing was used to analyze the alterations of LncRNA and mRNA expression in AKI model and LncRNA-A330074k22Rik (A33) knockdown cells, respectively. Renal in situ electrotransfer knockdown plasmid was used to establish mice model of AKI with low expression of A33 in kidney.

RESULTS

The results showed that HDG effectively alleviate cisplatin-induced kidney injury and inflammation in mice. Transcriptome sequencing results showed that multiple LncRNAs in kidney of AKI model exhibited significant changes, among which LncRNA-A33 had the most obvious change trend. Subsequent results showed that A33 was highly expressed in kidney of AKI mice and LPS-induced renal tubular cells. After in situ renal electroporation knockdown plasmid down-regulated A33 in kidney of AKI mice, it was found that inhibition of A33 could significantly relieve cisplatin-induced kidney injury and inflammation of AKI, while HDG could effectively suppress the expression of A33 in vitro and in vivo, respectively. Subsequently, transcriptome sequencing was again used to analyze the changes in mRNA expression of renal tubular cells after A33 knockdown by siRNA. The results showed that a large number of inflammation-related signaling pathways were down-regulated, Axin2 and its downstream β-catenin signal were significantly inhibited. Cell recovery test showed that HDG inhibited Axin2/β-catenin signal by down-regulating A33, and improved kidney injury and inflammation of AKI.

CONCLUSION

Taken together, HDG significantly ameliorated cisplatin-induced kidney injury through LncRNA-A330074k22Rik/Axin2/β-catenin signal axis, which providing a potential therapeutic approach for the treatment of AKI.

lncRNA MALAT1 Promotes Diabetic Nephropathy Progression via miR-15b-5p/TLR4 Signaling Axis

Objective

The long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) are closely associated with the pathogenesis of diabetic nephropathy (DN). But a complete mechanism for MALAT1 in DN has yet to be identified. This study investigated the effect of MALAT1 on DN through the regulation of miR-15b-5p/TLR4 signaling.

Method

Renal tissues were collected from DN patients. Human renal tubular epithelial cells (HK-2) were used as a model of DN induced by high glucose (HG). We then measured the viability, apoptosis, and inflammatory cytokine levels of HK-2 cells using the corresponding assays. Following transfections of si-MALAT1, si-MALAT1+miR-15b-5p inhibitor, or si-MALAT1+vector TLR4 into HG-stimulated HK-2 cells, cell viability, apoptosis, and inflammatory cytokines were again measured. Furthermore, dual-luciferase reporter assay validated the interactions of MALAT1/miR-15b-5p and miR-15b-5p/TLR4. In addition, the interaction between MALAT1 and miR-15b-5p was investigated by RNA immunoprecipitation (RIP).

Results

A significant upregulation of MALAT1 was observed in DN kidney tissues, as well as in HG-stimulated HK-2 cells. MALAT1 knockdown attenuates the inhibition of cell viability, apoptosis, and inflammatory response induced by HG in HK-2 cells. Moreover, a miR-15b-5p inhibitor or TLR4 overexpression reversed the above effects induced by MALAT1 knockdown.

Conclusion

These results indicate that reduced MALAT1 ameliorates HG-stimulated HK-2 cell damage through an inhibition of the miR-15b-5p/TLR4 axis. MALAT1 may serve as a biomarker and potential therapeutic target for DN.

LncRNA136131 suppresses apoptosis of renal tubular epithelial cells in acute kidney injury by targeting the miR-378a-3p/Rab10 axis

The pathogenesis of acute kidney injury (AKI) is not fully understood. To date, the exact role and regulatory mechanism of long non-coding RNA (lncRNA)136131 in AKI remains unclear. Here, we demonstrate that lncRNA136131 in BUMPT cells is induced by antimycin A. Furthermore, after incubating BUMPT cells in antimycin for two hours, lncRNA136131 prevented BUMPT cell apoptosis and cleaved caspase-3 expression. Mechanistically, lncRNA136131 sponged miR-378a-3p and then increased the expression of Rab10 to suppress apoptosis. Finally, I/R-induced decline of renal function, tubular damage, renal tubular cells apoptosis, and the upregulation of cleaved caspase-3 were aggravated by lncRNA136131 siRNA. In contrast, this effect was attenuated by the overexpression of lncRNA136131. In conclusion, lncRNA136131 protected against I/R-induced AKI progression by targeting miR-378a-3p/Rab10 and may be utilized as a novel target for AKI therapeutics.

Divergent regulation of lncRNA expression by ischemia in adult and aging mice

Elderly patients have increased susceptibility to acute kidney injury (AKI). Long noncoding RNAs (lncRNA) are key regulators of cellular processes, and have been implicated in both aging and AKI. Our aim was to study the effects of aging and ischemia-reperfusion injury (IRI) on the renal expression of lncRNAs. Adult and old (10- and 26-30-month-old) C57BL/6 N mice were subjected to unilateral IRI followed by 7 days of reperfusion. Renal expression of 90 lncRNAs and mRNA expression of injury, regeneration, and fibrosis markers was measured by qPCR in the injured and contralateral control kidneys. Tubular injury, regeneration, and fibrosis were assessed by histology. Urinary lipocalin-2 excretion was increased in old mice prior to IRI, but plasma urea was similar. In the control kidneys of old mice tubular cell necrosis and apoptosis, mRNA expression of kidney injury molecule-1, fibronectin-1, p16, and p21 was elevated. IRI increased plasma urea concentration only in old mice, but injury, regeneration, and fibrosis scores and their mRNA markers were similar in both age groups. AK082072 and Y lncRNAs were upregulated, while H19 and RepA transcript were downregulated in the control kidneys of old mice. IRI upregulated Miat, Igf2as, SNHG5, SNHG6, RNCR3, Malat1, Air, Linc1633, and Neat1 v1, while downregulated Linc1242. LncRNAs H19, AK082072, RepA transcript, and Six3os were influenced by both aging and IRI. Our results indicate that both aging and IRI alter renal lncRNA expression suggesting that lncRNAs have a versatile and complex role in aging and kidney injury. An Ingenuity Pathway Analysis highlighted that the most downregulated H19 may be linked to aging/senescence through p53.

Long Noncoding RNAs: Novel Important Players in Adipocyte Lipid Metabolism and Derivative Diseases

Obesity, a global public health issue, is characterized by excessive adiposity and is strongly related to some chronic diseases including cardiovascular diseases and diabetes. Extra energy intake-induced adipogenesis involves various transcription factors and long noncoding RNAs (lncRNAs) that control lipogenic mRNA expression. Currently, lncRNAs draw much attention for their contribution to adipogenesis and adipose tissue function. Increasing evidence also manifests the pivotal role of lncRNAs in modulating white, brown, and beige adipose tissue development and affecting the progression of the diseases induced by adipose dysfunction. The aim of this review is to summarize the roles of lncRNAs in adipose tissue development and obesity-caused diseases to provide novel drug targets for the treatment of obesity and metabolic diseases.

Intratumoral Fibrosis in Facilitating Renal Cancer Aggressiveness: Underlying Mechanisms and Promising Targets

Intratumoral fibrosis is a histologic manifestation of fibrotic tumor stroma. The interaction between cancer cells and fibrotic stroma is intricate and reciprocal, involving dysregulations from multiple biological processes. Different components of tumor stroma are implicated via distinct manners. In the kidney, intratumoral fibrosis is frequently observed in renal cell carcinoma (RCC). However, the underlying mechanisms remain largely unclear. In this review, we recapitulate evidence demonstrating how fibrotic stroma interacts with cancer cells and mechanisms shared between RCC tumorigenesis and renal fibrogenesis, providing promising targets for future studies.

LncRNA TUG1 regulates the development of ischemia-reperfusion mediated acute kidney injury through miR-494-3p/E-cadherin axis

Background

Acute kidney injury (AKI) results from renal dysfunction caused by various causes, resulting in high mortality. The underlying mechanisms of ischemia-reperfusion (I/R) induced AKI is very complicated and needed for further research. Here, we sought to found out the functions of lncRNA TUG1 in I/R-induced AKI.

Methods

In vivo model was constructed by I/R-induced mice and in vitro model was constructed by hypoxia/reoxygenation (H/R)-induced HK-2 cell. Kidney tissue damage was evaluated through H&E staining in mice. Cell flow cytometry was used to detect the degree of apoptosis. TUG1, miR-494-3p and E-cadherin were determined both by RT-PCR and western blot. Dual luciferase assay was employed to validate the relationships between TUG1, miR-494-3p and E-cadherin. Inflammatory factors including IL-1β, TNFɑ and IL-6 were evaluated by ELISA.

Results

lncRNA TUG1 was decreased while miR-494-3p was elevated in vivo and in vitro. Overexpression of TUG1 or transfection with miR-494-3p inhibitor significantly alleviated cell apoptosis. MiR-494-3p directly targeted E-cadherin and TUG1 suppressed cell apoptosis via serving as a miR-494-3p sponge to disinhibit E-cadherin.

Conclusion

lncRNA TUG1 alleviated I/R-induced AKI through targeting miR-494-3p/E-cadherin.

Non-Coding RNAs as Biomarkers and Therapeutic Targets for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the most common diabetic complication and is a leading cause of end-stage kidney disease. Increasing evidence shows that DKD is regulated not only by many classical signaling pathways but also by epigenetic mechanisms involving chromatin histone modifications, DNA methylation, and non-coding RNA (ncRNAs). In this review, we focus on our current understanding of the role and mechanisms of ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the pathogenesis of DKD. Of them, the regulatory role of TGF-β/Smad3-dependent miRNAs and lncRNAs in DKD is highlighted. Importantly, miRNAs and lncRNAs as biomarkers and therapeutic targets for DKD are also described, and the perspective of ncRNAs as a novel therapeutic approach for combating diabetic nephropathy is also discussed.

Differentially expressed lncRNAs in liver tissues of TX mice with hepatolenticular degeneration

Wilson's Disease (WD), an ATP7B-mutated inherited disease that affects copper transport, is characterised by liver and nervous system manifestations. Long non-coding (ln-c) RNAs are widely involved in almost all physiological and pathological processes in the body, and are associated with numerous diseases. The present study aimed to elucidate the lncRNA-mRNA regulation network in a TX WD mouse model using RNA sequencing (RNA-seq). lncRNA expression profiles were screened using RNA-seq and real-time polymerase chain reaction, and differentially expressed lncRNAs and mRNAs were identified. To analyse the biological functions and pathways for the differentially expressed mRNAs, gene ontology and pathway enrichment analyses were performed. A significantly correlated lncRNA-mRNA relationship pair was calculated by CNC analysis to construct differential lncRNA and mRNA co-expression networks. A total of 2564 significantly up-regulated and 1052 down-regulated lncRNAs, and 1576 up-regulated and 297 down-regulated mRNAs, were identified. These genes were found to be associated with key processes such as apoptosis, and KEGG analysis revealed enrichment in the drug metabolism-cytochrome P450 pathway, PPAR signalling pathway, Notch signalling pathway, and MAPK signalling pathway. The identified differential lncRNAs may be involved in the pathogenesis and development of WD liver injury.

Emerging role of long noncoding RNA-encoded micropeptides in cancer

Increasing evidence has indicated that long noncoding RNAs (lncRNAs) play various important roles in the development of cancers. The widespread applications of ribosome profiling and ribosome nascent chain complex sequencing revealed that some short open reading frames of lncRNAs have micropeptide-coding potential. The resulting micropeptides have been shown to participate in N6-methyladenosine modification, tumor angiogenesis, cancer metabolism, and signal transduction. This review summarizes current information regarding the reported roles of lncRNA-encoded micropeptides in cancer, and explores the potential clinical value of these micropeptides in the development of anti-cancer drugs and prognostic tumor biomarkers.

Emerging role of lncRNAs in renal fibrosis

Fibrosis is the final common pathological feature of a wide variety of chronic kidney disease (CKD). However, an understanding of the mechanisms underlying the development of renal fibrosis remains challenging and controversial. As the current focus of molecular research, noncoding RNAs (ncRNAs), mainly microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular noncoding RNAs (circRNAs), have powerful and abundant biological functions, which essentially makes them mediators of the physiological and pathological processes of various system diseases. The role of ncRNAs in renal fibrosis has also received great attention in recent years, but most research has mainly focused on miRNAs. In fact, although a large number of studies of lncRNAs have emerged recently, the role these molecules play in renal fibrosis haven't been fully understood till now. Thus, this review discusses the discovery of lncRNAs and their biological functions in different types of renal fibrosis, as well as the imminent applications of these findings in clinical use. Undoubtedly, in the future, further understanding of the function of all types of lncRNAs will reveal large breakthroughs in the treatment of renal fibrosis.

Peritoneal fibrosis and epigenetic modulation

Peritoneal dialysis (PD) is an effective treatment for patients with end-stage renal disease. However, peritoneal fibrosis (PF) is a common complication that ultimately leads to ultrafiltration failure and discontinuation of PD after long-term PD therapy. There is currently no effective therapy to prevent or delay this pathologic process. Recent studies have reported epigenetic modifications involved in PF, and accumulating evidence suggests that epigenetic therapies may have the potential to prevent and treat PF clinically. The major epigenetic modifications in PF include DNA methylation, histone modification, and noncoding RNAs. The mechanisms of epigenetic regulation in PF are complex, predominantly involving modification of signaling molecules, transcriptional factors, and genes. This review will describe the mechanisms of epigenetic modulation in PF and discuss the possibility of targeting them to prevent and treat this complication.

LncRNA MALAT1 promoted high glucose-induced pyroptosis of renal tubular epithelial cell by sponging miR-30c targeting for NLRP3

Diabetic nephropathy (DN), characterized by the chronic loss of kidney function during diabetes, is a long-term kidney disease that affects millions of populations. However, the etiology of DN remains unclear. DN cell model was established by treating HK-2 cells with high glucose (HG) in vitro. Expression of metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), miR-30c, nucleotide binding and oligomerization domain-like receptor protein 3 (NLRP3), caspase-1, IL-1β, and IL-18 in treated HK-2 cells were tested by quantitative polymerase chain reaction. HK-2 cell pyroptosis was assessed using flow cytometry analysis. Lactate dehydrogenase (LDH) activity was examined with a LDH assay kit. Correlation among MALAT1, miR-30c, and NLRP3 was examined via dual-luciferase reporter assay. Here, we revealed that MALAT1 was upregulated, but miR-30c was downregulated in HG-treated HK-2 cells, leading to upregulation of NLRP3 expression and cell pyroptosis. Knockdown of MALAT1 or overexpression of miR-30c protected HK-2 cells from HG-induced pyroptosis. Meanwhile, we found that MALAT1 promoted NLRP3 expression by sponging miR-30c through dual-luciferase reporter assay. Moreover, the co-transfection of sh-MALAT1 and miR-30c inhibitor could reverse the protective effects of the sh-MALAT1 on the HG-induced pyroptosis. These results confirmed that MALAT1 regulated HK-2 cell pyroptosis by inhibiting miR-30c targeting for NLRP3, contributing to a better understanding of DN pathogenesis and help to find out the effective treatment for DN.

Potential Roles of Long Noncoding RNAs as Therapeutic Targets in Renal Fibrosis

Many studies have made clear that most of the genome is transcribed into noncoding RNAs, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), both of which can affect different cell features. LncRNAs are long heterogeneous RNAs that regulate gene expression and a variety of signaling pathways involved in cellular homeostasis and development. Several studies have demonstrated that lncRNA is an important class of regulatory molecule that can be targeted to change cellular physiology and function. The expression or dysfunction of lncRNAs is closely related to various hereditary, autoimmune, and metabolic diseases, and tumors. Specifically, recent work has shown that lncRNAs have an important role in kidney pathogenesis. The effective roles of lncRNAs have been recognized in renal ischemia, injury, inflammation, fibrosis, glomerular diseases, renal transplantation, and renal-cell carcinoma. The present review focuses on the emerging role and function of lncRNAs in the pathogenesis of kidney inflammation and fibrosis as novel essential regulators. Although lncRNAs are important players in the initiation and progression of many pathological processes, their role in renal fibrosis remains unclear. This review summarizes the current understanding of lncRNAs in the pathogenesis of kidney fibrosis and elucidates the potential role of these novel regulatory molecules as therapeutic targets for the clinical treatment of kidney inflammation and fibrosis.

Diverse Role of TGF-β in Kidney Disease

Inflammation and fibrosis are two pathological features of chronic kidney disease (CKD). Transforming growth factor-β (TGF-β) has been long considered as a key mediator of renal fibrosis. In addition, TGF-β also acts as a potent anti-inflammatory cytokine that negatively regulates renal inflammation. Thus, blockade of TGF-β inhibits renal fibrosis while promoting inflammation, revealing a diverse role for TGF-β in CKD. It is now well documented that TGF-β1 activates its downstream signaling molecules such as Smad3 and Smad3-dependent non-coding RNAs to transcriptionally and differentially regulate renal inflammation and fibrosis, which is negatively regulated by Smad7. Therefore, treatments by rebalancing Smad3/Smad7 signaling or by specifically targeting Smad3-dependent non-coding RNAs that regulate renal fibrosis or inflammation could be a better therapeutic approach. In this review, the paradoxical functions and underlying mechanisms by which TGF-β1 regulates in renal inflammation and fibrosis are discussed and novel therapeutic strategies for kidney disease by targeting downstream TGF-β/Smad signaling and transcriptomes are highlighted.

Identifying 4 Novel lncRNAs as Potential Biomarkers for Acute Rejection and Graft Loss of Renal Allograft

Acute rejection (AR) after kidney transplant is one of the major obstacles to obtain ideal graft survival. Reliable molecular biomarkers for AR and renal allograft loss are lacking. This study was performed to identify novel long noncoding RNAs (lncRNAs) for diagnosing AR and predicting the risk of graft loss. The several microarray datasets with AR and nonrejection specimens of renal allograft downloaded from Gene Expression Omnibus database were analyzed to screen differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs). Univariate and multivariate Cox regression analyses were used to identify optimal prognosis-related DElncRNAs for constructing a risk score model. 39 common DElncRNAs and 185 common DEmRNAs were identified to construct a lncRNA-mRNA regulatory relationship network. DElncRNAs were revealed to regulate immune cell activation and proliferation. Then, 4 optimal DElncRNAs, ATP1A1-AS1, CTD-3080P12.3, EMX2OS, and LINC00645, were selected from 17 prognostic DElncRNAs to establish the 4-lncRNA risk score model. In the training set, the high-risk patients were more inclined to graft loss than the low-risk patients. Time-dependent receiver operating characteristics analysis revealed the model had good sensitivity and specificity in prediction of 1-, 2-, and 3-year graft survival after biopsy (AUC = 0.891, 0.836, and 0.733, respectively). The internal testing set verified the result well. Gene set enrichment analysis which expounded NOD-like receptor, the Toll-like receptor signaling pathways, and other else playing important role in immune response was enriched by the 4 lncRNAs. Allograft-infiltrating immune cells analysis elucidated the expression of 4 lncRNAs correlated with gamma delta T cells and eosinophils, etc. Our study identified 4 novel lncRNAs as potential biomarkers for AR of renal allograft and constructed a lncRNA-based model for predicting the risk of graft loss, which would provide new insights into mechanisms of AR.

NORAD affects the progression of diabetic nephropathy through targeting miR-520h to upregulate TLR4

To uncover the role of NORAD in the progression of diabetic nephropathy (DN) and the underlying mechanism. Relative levels of NORAD and TLR4 in db/m mice and db/db mice were tested. Meanwhile, their levels in glomerular mesangial cells undergoing high-level (H-MC group) or low-level (L-MC) glucose treatment were determined. Regulatory effects of NORAD and TLR4 on proliferative ability and apoptosis in SV40-MES-13 cells were assessed. The interaction in the regulatory loop NORAD/miR-520h/TLR4 was verified through dual-luciferase reporter gene assay, determination of subcellular distribution and RIP (RNA Immunoprecipitation) assay. At last, potential role of the regulatory loop NORAD/miR-520h/TLR4 in regulating DN was clarified. NORAD and TLR4 were upregulated in db/db mice and SV40-MES-13 cells in H-MC group. Overexpression of them promoted proliferative ability and inhibited apoptosis in SV40-MES-13 cells. MiR-520h was confirmed to bind NORAD and TLR4. NORAD, miR-520h and TLR4 were mainly distributed in cytoplasm, which were enriched in anti-Ago2. The regulatory loop NORAD/miR-520h/TLR4 has been demonstrated to promote the progression of DN. The regulatory loop NORAD/miR-520h/TLR4 promotes the proliferative ability and inhibits apoptosis in glomerular mesangial cells, thus aggravating the progression of DN.

Circular RNA Expression Profiles in Vaginal Epithelial Tissue of Women With Lubrication Disorders

INTRODUCTION

Recently, circular RNA (circRNA) has been proved to occupy a vital pathological position in many diseases by acting as microRNAs sponges. However, the role of circRNA in female sexual dysfunction (FSD), especially in lubrication disorders (LDs), remains unclear.

AIM

The aim of this study was to detect circRNA expression in LDs, analyzed target genes, and pathways regulated by the differently expressed circRNAs.

METHODS

In this study, next-generation sequencing was first conducted to produce circRNA expression profiles of FSD groups and normal control groups. Furthermore, differences in expression of 6 randomly selected circRNAs were confirmed through real-time quantitative polymerase chain reaction. Kyoto Encyclopedia of Genes and Genomes biological pathway analysis and Gene Ontology showed that immune processes and infection could be involved in the development of FSDs.

MAIN OUTCOME MEASURE

CircRNA expression in vaginal epithelial tissue obtained from women with LDs have been detected. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes biological pathway analysis, and circRNA-microRNA interaction predictions were investigated.

RESULTS

Totally, 7,746 circRNAs of vaginal epithelial tissue from women of 2 groups were sequenced. Preliminary judgment revealed that there were 73 circRNAs that have significant differential expression, including 53 downregulated circRNAs and 20 upregulated circRNAs. Research results also displayed that the majority of circRNAs has multiple binding sites of microRNAs, including miR-137, which has been reported to be linked to FSD.

CLINICAL IMPLICATIONS

We predicted 10 circRNAs paired with hsa-miR-137-5p, but the mechanism of circRNA involvement in disease development remains to be further explored.

STRENGTHS & LIMITATIONS

For the first time, the research disclosed the potential pathogenesis of LDs. However, we only analyzed the expression profile of circRNA in FSD, no specific mechanism was further confirmed or proposed. We still have a preliminary understanding, and more research is needed to explore the target of FSD treatment.

CONCLUSION

The results suggest that circRNAs have different expression in the FSD groups and play a vital part in the occurrence and development of FSD. Zhang J, Xia H, Zhang A, et al. Circular RNA Expression Profiles in Vaginal Epithelial Tissue of Women With Lubrication Disorders. J Sex Med 2019;16:1696-1707.

Long noncoding RNA: an emerging player in diabetes and diabetic kidney disease

Diabetic kidney disease (DKD) is among the most common complications of diabetes mellitus (DM), and remains the leading cause of end-stage renal diseases (ESRDs) in developed countries, with no definitive therapy yet available. It is imperative to decipher the exact mechanisms underlying DKD and identify novel therapeutic targets. Burgeoning evidence indicates that long non-coding RNAs (lncRNAs) are essential for diverse biological processes. However, their roles and the mechanisms of action remain to be defined in disease conditions like diabetes and DKD. The pathogenesis of DKD is twofold, so is the principle of treatments. As the underlying disease, diabetes per se is the root cause of DKD and thus a primary focus of therapy. Meanwhile, aberrant molecular signaling in kidney parenchymal cells and inflammatory cells may directly contribute to DKD. Evidence suggests that a number of lncRNAs are centrally involved in development and progression of DKD either via direct pathogenic roles or as indirect mediators of some nephropathic pathways, like TGF-β1, NF-κB, STAT3 and GSK-3β signaling. Some lncRNAs are thus likely to serve as biomarkers for early diagnosis or prognosis of DKD or as therapeutic targets for slowing progression or even inducing regression of established DKD. Here, we elaborated the latest evidence in support of lncRNAs as a key player in DKD. In an attempt to strengthen our understanding of the pathogenesis of DKD, and to envisage novel therapeutic strategies based on targeting lncRNAs, we also delineated the potential mechanisms of action as well as the efficacy of targeting lncRNA in preclinical models of DKD.

The role of extracellular vesicles in renal fibrosis

As a particularly important mediator of intercellular communication, extracellular vesicles (EVs) have been proved to be extensively involved in various system diseases over the past two decades, including in renal diseases. As is well-known, renal fibrosis is the common pathological process of any ongoing renal disease or adaptive repair of kidney injury based on current knowledge. Although much work has been performed focusing on EVs in various renal diseases, the role of EVs in renal fibrosis has not been described in detail and summarized. In this review, we provide a brief overview of the definition, classification and biological process of EVs. Then, the potential mechanisms of EVs in renal fibrosis are illustrated. Lastly, recent advances in EVs and the implications of EVs for diagnosis and therapy in renal fibrosis disease are introduced. We look forward to a more comprehensive understanding of EVs in renal fibrosis, which could be a boon to patients with renal fibrosis disease.

Non-Coding RNAs as New Therapeutic Targets in the Context of Renal Fibrosis

Fibrosis, or tissue scarring, is defined as the excessive, persistent and destructive accumulation of extracellular matrix components in response to chronic tissue injury. Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function. Limited therapeutic options are available and the molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the role of non-coding RNAs, and in particular microRNAs (miRNAs), has been described in kidney fibrosis. Seminal studies have highlighted their potential importance as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review will summarize recent scientific advances and will discuss potential clinical applications as well as future research directions.

Non-coding RNAs in kidney injury and repair

Acute kidney injury (AKI) is a major kidney disease featured by a rapid decline of renal function. Pathologically, AKI is characterized by tubular epithelial cell injury and death. Besides its acute consequence, AKI contributes critically to the development and progression of chronic kidney disease (CKD). After AKI, surviving tubular cells regenerate to repair. Normal repair restores tubular integrity, while maladaptive or incomplete repair results in renal fibrosis and eventually CKD. Non-coding RNAs (ncRNAs) are functional RNA molecules that are transcribed from DNA but not translated into proteins, which mainly include microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), small nucleolar RNAs (snoRNAs), and tRNAs. Accumulating evidence suggests that ncRNAs play important roles in kidney injury and repair. In this review, we summarize the recent advances in the understanding of the roles of ncRNAs, especially miRNAs and lncRNAs in kidney injury and repair, discuss the potential application of ncRNAs as biomarkers of AKI as well as therapeutic targets for treating AKI and impeding AKI-CKD transition, and highlight the future research directions of ncRNAs in kidney injury and repair.