miR-185 affected the EMT, cell viability, and proliferation via DNMT1/MEG3 pathway in TGF-β1-induced renal fibrosis

A systematic review of epigenetic interplay in kidney diseases: Crosstalk between long noncoding RNAs and methylation, acetylation of chromatin and histone

The intricate crosstalk between long noncoding RNAs (lncRNAs) and epigenetic modifications such as chromatin/histone methylation and acetylation offer new perspectives on the pathogenesis and treatment of kidney diseases. lncRNAs, a class of transcripts longer than 200 nucleotides with no protein-coding potential, are now recognized as key regulatory molecules influencing gene expression through diverse mechanisms. They modulate the epigenetic modifications by recruiting or blocking enzymes responsible for adding or removing methyl or acetyl groups, such as DNA, N6-methyladenosine (m6A) and histone methylation and acetylation, subsequently altering chromatin structure and accessibility. In kidney diseases such as acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy (DN), glomerulonephritis (GN), and renal cell carcinoma (RCC), aberrant patterns of DNA/RNA/histone methylation and acetylation have been associated with disease onset and progression, revealing a complex interplay with lncRNA dynamics. Recent studies have highlighted how lncRNAs can impact renal pathology by affecting the expression and function of key genes involved in cell cycle control, fibrosis, and inflammatory responses. This review will separately address the roles of lncRNAs and epigenetic modifications in renal diseases, with a particular emphasis on elucidating the bidirectional regulatory effects and underlying mechanisms of lncRNAs in conjunction with DNA/RNA/histone methylation and acetylation, in addition to the potential exacerbating or renoprotective effects in renal pathologies. Understanding the reciprocal relationships between lncRNAs and epigenetic modifications will not only shed light on the molecular underpinnings of renal pathologies but also present new avenues for therapeutic interventions and biomarker development, advancing precision medicine in nephrology.

A preliminary study of the miRNA restitution effect on CNV-induced miRNA downregulation in CAKUT

BACKGROUND

The majority of CAKUT-associated CNVs overlap at least one miRNA gene, thus affecting the cellular levels of the corresponding miRNA. We aimed to investigate the potency of restitution of CNV-affected miRNA levels to remediate the dysregulated expression of target genes involved in kidney physiology and development in vitro.

METHODS

Heterozygous MIR484 knockout HEK293 and homozygous MIR185 knockout HEK293 cell lines were used as models depicting the deletion of the frequently affected miRNA genes by CAKUT-associated CNVs. After treatment with the corresponding miRNA mimics, the levels of the target genes have been compared to the non-targeting control treatment. For both investigated miRNAs, MDM2 and PKD1 were evaluated as common targets, while additional 3 genes were investigated as targets of each individual miRNA (NOTCH3, FIS1 and APAF1 as hsa-miR-484 targets and RHOA, ATF6 and CDC42 as hsa-miR-185-5p targets).

RESULTS

Restitution of the corresponding miRNA levels in both knockout cell lines has induced a change in the mRNA levels of certain candidate target genes, thus confirming the potential to alleviate the CNV effect on miRNA expression. Intriguingly, HEK293 WT treatment with investigated miRNA mimics has triggered a more pronounced effect, thus suggesting the importance of miRNA interplay in different genomic contexts.

CONCLUSIONS

Dysregulation of multiple mRNA targets mediated by CNV-affected miRNAs could represent the underlying mechanism behind the unresolved CAKUT occurrence and phenotypic variability observed in CAKUT patients. Characterizing miRNAs located in CNVs and their potential to become molecular targets could eventually help in understanding and improving the management of CAKUT.

Shen Qi Wan attenuates renal interstitial fibrosis through upregulating AQP1

Renal interstitial fibrosis (RIF) is the crucial pathway in chronic kidney disease (CKD) leading to the end-stage renal failure. However, the underlying mechanism of Shen Qi Wan (SQW) on RIF is not fully understood. In the current study, we investigated the role of Aquaporin 1 (AQP1) in SQW on tubular epithelial-to-mesenchymal transition (EMT). A RIF mouse model induced by adenine and a TGF-β1-stimulated HK-2 cell model were etablished to explore the involvement of AQP 1 in the protective effect of SQW on EMT in vitro and in vivo. Subsequently, the molecular mechanism of SQW on EMT was explored in HK-2 cells with AQP1 knockdown. The results indicated that SQW alleviated kidney injury and renal collagen deposition in the kidneys of mice induced by adenine, increased the protein expression of E-cadherin and AQP1 expression, and decreased the expression of vimentin and α-smooth muscle actin (α-SMA). Similarly, treatmement with SQW-containing serum significantly halted EMT process in TGF-β1 stimulated HK-2 cells. The expression of snail and slug was significantly upregulated in HK-2 cells after knockdown of AQP1. AQP1 knockdown also increased the mRNA expression of vimentin and α-SMA, and decreased the expression of E-cadherin. The protein expression of vimentin increased, while the expression of E-cadherin and CK-18 significantly decreased after AQP1 knockdown in HK-2 cells. These results revealed that AQP1 knockdown promoted EMT. Furthermore, AQP1 knockdown abolished the protective effect of SQW-containing serum on EMT in HK-2 cells. In sum, SQW attentuates EMT process in RIF through upregulation of the expression of AQP1.

Epigenetics as a versatile regulator of fibrosis

Fibrosis, a process caused by excessive deposition of extracellular matrix (ECM), is a common cause and outcome of organ failure and even death. Researchers have made many efforts to understand the mechanism of fibrogenesis and to develop therapeutic strategies; yet, the outcome remains unsatisfactory. In recent years, advances in epigenetics, including chromatin remodeling, histone modification, DNA methylation, and noncoding RNA (ncRNA), have provided more insights into the fibrotic process and have suggested the possibility of novel therapy for organ fibrosis. In this review, we summarize the current research on the epigenetic mechanisms involved in organ fibrosis and their possible clinical applications.

Epigenetic changes induced by pathogenic Chlamydia spp

Chlamydia trachomatis, C. pneumoniae, and C. psittaci, the three Chlamydia species known to cause human disease, have been collectively linked to several pathologies, including conjunctivitis, trachoma, respiratory disease, acute and chronic urogenital infections and their complications, and psittacosis. In vitro, animal, and human studies also established additional correlations, such as between C. pneumoniae and atherosclerosis and between C. trachomatis and ovarian cancer. As part of their survival and pathogenesis strategies as obligate intracellular bacteria, Chlamydia spp. modulate all three major types of epigenetic changes, which include deoxyribonucleic acid (DNA) methylation, histone post-translational modifications, and microRNA-mediated gene silencing. Some of these epigenetic changes may be implicated in key aspects of pathogenesis, such as the ability of the Chlamydia spp. to induce epithelial-to-mesenchymal transition, interfere with DNA damage repair, suppress cholesterol efflux from infected macrophages, act as a co-factor in human papillomavirus (HPV)-mediated cervical cancer, prevent apoptosis, and preserve the integrity of mitochondrial networks in infected host cells. A better understanding of the individual and collective contribution of epigenetic changes to pathogenesis will enhance our knowledge about the biology of Chlamydia spp. and facilitate the development of novel therapies and biomarkers. Pathogenic Chlamydia spp. contribute to epigenetically-mediated gene expression changes in host cells by multiple mechanisms.

Serum non-coding RNAs for diagnosis and stage of liver fibrosis

Background

All chronic liver diseases could lead to liver fibrosis. Accurate diagnosis and stage of fibrosis were important for the medical determination, management, and therapy. Liver biopsy was considered to be the gold criteria of fibrosis diagnosis. However, liver biopsy was an invasive method with some drawbacks. Non‐invasive tests for liver fibrosis included radiologic method and serum‐based test. Radiologic examination was influenced by obesity, cost, and availability. Serum‐based test was widely used in the screening and diagnostic of liver fibrosis. However, the accuracy was still needed to be improved.

Methods

Recent studies showed serum non‐coding RNAs: microRNA, long non‐coding RNA(lncRNA), and circular RNA(circRNA), which have the potentiality to be non‐invasive markers for liver fibrosis. The recent progress was summarized in this review.

Results

These studies showed serum non‐coding RNAs exerted a good diagnostic performance for liver fibrosis. A panel that included several non‐coding RNAs could increase the accuracy of single marker.

Conclusions

Serum microRNAs, lncRNAs, and circRNAs could be potential non‐invasive markers for diagnosis and stage of liver fibrosis. More high‐quality clinical study is needed for further research.

Tumor necrosis factor-α coordinates with transforming growth factor-β1 to induce epithelial-mesenchymal transition and migration via the NF-κB/NOX4 pathway in bronchial epithelial cells

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is the process by which epithelial cells transform into mesenchymal cells, which plays a significant role in lung fibrotic disease. Transforming growth factor-β1(TGF-β1) is considered to be the most effective EMT inducer. The purpose of this study was to investigate the effect of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) on TGF-β1-induced EMT and the underlying mechanisms in the human bronchial epithelial cell line BEAS-2B.

METHODS

Human bronchial epithelial BEAS-2B cells were treated with TGF-β1 and TNF-α separately or in combination for 24 h, and qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to investigate the EMT process. Moreover, to further explore the effect of the NF-κB pathway on the EMT process, inhibitor assays (BAY-117082, NF-κB inhibitor), wound healing assays, and western blotting were performed.

RESULTS

The results showed that both cytokines enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells. In addition, combined treatment with TNF-α and TGF-β1 further reduced E-cadherin expression, which conversely elevated α-SMA and vimentin mRNA and protein levels. Correspondingly, the migration rate of BEAS-2B cells was also increased. Furthermore, inhibiting the NF-κB signaling pathway blocked the expression of EMT-related markers and NOX4 induced by TGF-β1 and TNF-α, as well as cell migration.

CONCLUSION

Taken together, TNF-α and TGF-β1 cooperatively promoted EMT and cell migration in BEAS-2B cells through the NF-κB/NOX4 signaling pathway.

Epigenetic regulation in radiation-induced pulmonary fibrosis

PURPOSE

Radiation-induced pulmonary fibrosis (RIPF) is a common and serious adverse effect of radiotherapy for thoracic tumors, which occurs in the irreversible stage of radiation-induced lung injury (RILI) >6 months after irradiation. It is characterized by progressive and irreversible destruction of lung tissue and deterioration of lung function, which may impair quality of life and lead to respiratory failure and death. We hope this will draw attention to the involvement of epigenetics in the regulation of RIPF.

CONCLUSIONS

This review summarizes research progress on the role and mechanism of DNA methylation, noncoding RNA and RNA methylation in RIPF or RILI, and the possible role and mechanism of histone modification in RIPF. We have noticed that in tissue fibrosis, the epigenetic regulation mechanisms inside and outside the nucleus can influence each other. We speculate that RIPF may be regulated by an epigenetic regulatory network during its development, and believe that TGF-β, SNAIL, PTEN and EZH2 are four targets worthy of in-depth study.

Fucoidan-Mediated Inhibition of Fibrotic Properties in Oral Submucous Fibrosis via the MEG3/miR-181a/Egr1 Axis

Oral submucous fibrosis (OSF) is a chronic fibrotic remodeling disease that can progress to oral cancer. However, efficient clinical diagnosis and treatment methods for OSF are still lacking. This study investigated the anti-fibrotic effect of fucoidan on oral fibrosis. To evaluate the fibrotic ability (myofibroblast activities), we performed wound-healing, Transwell migration, and collagen contraction assays by using patient-derived normal and fibrotic buccal submucous fibroblasts (BMFs and fBMFs, respectively). RNA-sequencing and dual-luciferase reporter and RNA immunoprecipitation chip assays were performed to identify the clinical significance and molecular mechanism of non-coding RNAs. Fucoidan suppressed the myofibroblast activities and inhibited the MEG3 in fBMFs. MEG3 was overexpressed in the OSF tissue and was positively associated with myofibroblast markers. Knockdown of MEG3 markedly inhibited myofibroblast activities, which were restored by inhibiting miR-181a and overexpressing Egr1. The results from luciferase reporter and RIP assays confirmed that MEG3 functioned as a competing endogenous RNA (ceRNA) and could directly target miR-181a, thereby preventing the miR-181a-mediated translational repression of Egr1. This study demonstrated that MEG3 exerts a profibrotic effect on OSF by targeting miR-181a/Egr1. Therefore, the administration of fucoidan may serve as a potential therapeutic strategy for OSF by targeting the overexpression of MEG3.

LncRNA-Dependent Mechanisms of Transforming Growth Factor-β: From Tissue Fibrosis to Cancer Progression

Transforming growth factor-β (TGF-β) is a crucial pathogenic mediator of inflammatory diseases. In tissue fibrosis, TGF-β regulates the pathogenic activity of infiltrated immunocytes and promotes extracellular matrix production via de novo myofibroblast generation and kidney cell activation. In cancer, TGF-β promotes cancer invasion and metastasis by enhancing the stemness and epithelial mesenchymal transition of cancer cells. However, TGF-β is highly pleiotropic in both tissue fibrosis and cancers, and thus, direct targeting of TGF-β may also block its protective anti-inflammatory and tumor-suppressive effects, resulting in undesirable outcomes. Increasing evidence suggests the involvement of long non-coding RNAs (lncRNAs) in TGF-β-driven tissue fibrosis and cancer progression with a high cell-type and disease specificity, serving as an ideal target for therapeutic development. In this review, the mechanism and translational potential of TGF-β-associated lncRNAs in tissue fibrosis and cancer will be discussed.

LncRNA MEG3 restrained pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy

Long noncoding RNA maternally expressed gene 3 (lncRNA MEG3) was down-regulated in pulmonary fibrosis of rats induced by Nickel oxide nanoparticles (NiO NPs), while the downstream regulatory mechanisms of MEG3 remain unclear. This study aimed to investigate the relationship among MEG3, Hedgehog (Hh) signaling pathway and autophagy in pulmonary fibrosis caused by NiO NPs. The pulmonary fibrosis model in rats was constructed by intratracheal instillation of 0.015, 0.06, and 0.24 mg/kg NiO NPs twice a week for 9 weeks. Collagen deposition model was established by treating A549 cells with 25, 50, and 100 μg/mL NiO NPs for 24 h. Our results indicated that NiO NPs activated Hh pathway, down-regulated the expression of MEG3, and reduced autophagy activity in vivo and in vitro. Meanwhile, the autophagy process was promoted by Hh pathway inhibitor (CDG-0449), while the collagen formation in A549 cells was reduced by autophagy activator (Rapamycin). Furthermore, the overexpressed MEG3 inhibited the activation of Hh pathway, resulting in autophagy activity enhancement along with collagen formation reduction. In summary, lncRNA MEG3 can restrain pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy, which may serve as a potential therapeutic strategy for pulmonary fibrosis.

Long non-coding RNA MEG3 promotes cisplatin-induced nephrotoxicity through regulating AKT/TSC/mTOR-mediated autophagy

Cis-Diamminedichloroplatinum (II) (DDP)-induced nephrotoxicity (DDPIN) may cause irreversible renal injury associated with high morbidity and mortality. Current standard therapies have not achieved satisfactory clinical outcomes due to unclear molecular and cellular mechanisms. Therefore, exploring potential therapies on DDPIN represents an urgent medical need. Present study characterized the role of lncRNA maternally expressed gene 3 (lnc-MEG3) in the pathogenesis of DDPIN. In both in vitro and in murine models of DDP-induced nephrotoxicity, lnc-MEG3 exacerbated DDPIN by negatively regulating miRNA-126 subsequently causing a decreased AKT/TSC/mTOR-mediated autophagy. By silencing lnc-MEG3 or incorporating miRNA-126 mimetics, the proliferation and migration of DDP-treated cells were restored. In vivo, we identified Paeonol to alleviate DDPIN by the inhibition of lnc-MEG3. Taken together, lnc-MEG3 represents a novel therapeutic target for DDPIN and Paeonol may serve as a promising treatment by inhibiting lnc-MEG3 and its related signaling pathways.

Long Non-coding RNA: An Emerging Contributor and Potential Therapeutic Target in Renal Fibrosis

Renal fibrosis (RF) is a pathological process that culminates in terminal renal failure in chronic kidney disease (CKD). Fibrosis contributes to progressive and irreversible decline in renal function. However, the molecular mechanisms involved in RF are complex and remain poorly understood. Long non-coding RNAs (lncRNAs) are a major type of non-coding RNAs, which significantly affect various disease processes, cellular homeostasis, and development through multiple mechanisms. Recent investigations have implicated aberrantly expressed lncRNA in RF development and progression, suggesting that lncRNAs play a crucial role in determining the clinical manifestation of RF. In this review, we comprehensively evaluated the recently published articles on lncRNAs in RF, discussed the potential application of lncRNAs as diagnostic and/or prognostic biomarkers, proposed therapeutic targets for treating RF-associated diseases and subsequent CKD transition, and highlight future research directions in the context of the role of lncRNAs in the development and treatment of RF.

Epigenetic modifications and the development of kidney graft fibrosis

PURPOSE OF REVIEW

To outline recent discoveries in epigenetic regulatory mechanisms that have potential implications in the development of renal fibrosis following kidney transplantation.

RECENT FINDINGS

The characterization of renal fibrosis following kidney transplantation has shown TGFβ/Smad signaling to play a major role in the progression to chronic allograft dysfunction. The onset of unregulated proinflammatory pathways are only exacerbated by the decline in regulatory mechanisms lost with progressive patient age and comorbidities such as hypertension and diabetes. However, significant developments in the recognition of epigenetic regulatory markers upstream of aberrant TGFβ-signaling has significant clinical potential to provide therapeutic targets for the treatment of renal fibrosis. In addition, discoveries in extracellular vesicles and the characterization of their cargo has laid new framework for the potential to evaluate patient outcomes independent of invasive biopsies.

SUMMARY

The current review summarizes the main findings in epigenetic machinery specific to the development of renal fibrosis and highlights therapeutic options that have significant potential to translate into clinical practice.

LncRNA MEG3 mediates nickel oxide nanoparticles-induced pulmonary fibrosis via suppressing TGF-β1 expression and epithelial-mesenchymal transition process

Nickel oxide nanoparticles (NiO NPs) causes pulmonary fibrosis via activating transforming growth factor-β1 (TGF-β1) in rats, but its upstream regulatory mechanisms are unknown. This study aimed to explore the role of long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) in NiO NPs-induced collagen deposition. Male Wistar rats were intratracheally instilled with NiO NPs (0.015, 0.06, and 0.24 mg/kg b.w.) twice a week for 9 weeks. Human lung adenocarcinoma epithelial cells (A549 cells) were cultured with NiO NPs (25, 50, and 100 μg/ml) to establish collagen deposition model. We discovered that NiO NPs-induced rat pulmonary fibrosis was accompanied by the epithelial-mesenchymal transition (EMT) occurrence and MEG3 down-regulation in rat lung tissues. In cell collagen deposition model, NiO NPs also evoked EMT and decreased MEG3 expression in a dose-dependent manner in A549 cells. By overexpressing MEG3 in A549 cells, we found that MEG3 inhibited the level of TGF-β1, EMT process and collagen formation. Moreover, our data showed that SB431542 (TGF-β1 inhibitor) had an inhibitory effect on NiO NPs-induced EMT and collagen formation. Our results indicated that MEG3 inhibited NiO NPs-induced collagen deposition by regulating TGF-β1-mediated EMT process, which may provide some clues for insighting into the mechanisms of NiO NPs-induced pulmonary fibrosis.

Transforming Growth Factor-β and Long Non-coding RNA in Renal Inflammation and Fibrosis

Renal fibrosis is one of the most characterized pathological features in chronic kidney disease (CKD). Progressive fibrosis eventually leads to renal failure, leaving dialysis or allograft transplantation the only clinical option for CKD patients. Transforming growth factor-β (TGF-β) is the key mediator in renal fibrosis and is an essential regulator for renal inflammation. Therefore, the general blockade of the pro-fibrotic TGF-β may reduce fibrosis but may risk promoting renal inflammation and other side effects due to the diverse role of TGF-β in kidney diseases. Long non-coding RNAs (lncRNAs) are RNA transcripts with more than 200 nucleotides and have been regarded as promising therapeutic targets for many diseases. This review focuses on the importance of TGF-β and lncRNAs in renal inflammation, fibrogenesis, and the potential applications of TGF-β and lncRNAs as the therapeutic targets and biomarkers in renal fibrosis and CKD are highlighted.

Inhibition of CTCF-regulated miRNA-185-5p mitigates renal interstitial fibrosis of chronic kidney disease

Aim: The present study aimed to elucidate the effect of CTCF on renal interstitial fibrosis in chronic kidney disease (CKD) and underlying mechanisms. Materials & methods: We measured NPHS2 expression and investigated its function in a unilateral ureteral obstruction-induced mouse model of CKD. Results: NPHS2 was poorly expressed in CKD mice. miR-185-5p targeted NPHS2 and reduced its expression, leading to increased α-SMA and COL I/III expression, increased renal interstitial fibrosis area and elevated phosphorylated vasodilator-stimulated phosphoprotein/vasodilator-stimulated phosphoprotein ratio. Co-treatment with CTCF downregulated miR-185-5p expression and abolished its effects in the CKD model. Conclusion: CTCF suppressed miR-185-5p and upregulated its target NPHS2, with a net effect of alleviating renal interstitial fibrosis in CKD.

MicroRNA Signatures Associated with Bronchopulmonary Dysplasia Severity in Tracheal Aspirates of Preterm Infants

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease that develops in neonates as a consequence of preterm birth, arrested fetal lung development, and inflammation. The incidence of BPD remains on the rise as a result of increasing survival of extremely preterm infants. Severe BPD contributes to significant health care costs and is associated with prolonged hospitalizations, respiratory infections, and neurodevelopmental deficits. In this study, we aimed to detect novel biomarkers of BPD severity. We collected tracheal aspirates (TAs) from preterm babies with mild/moderate (n = 8) and severe (n = 17) BPD, and we profiled the expression of 1048 miRNAs using a PCR array. Associations with biological pathways were determined with the Ingenuity Pathway Analysis (IPA) software. We found 31 miRNAs differentially expressed between the two disease groups (2-fold change, false discovery rate (FDR) < 0.05). Of these, 4 miRNAs displayed significantly higher expression levels, and 27 miRNAs had significantly lower expression levels in the severe BPD group when compared to the mild/moderate BPD group. IPA identified cell signaling and inflammation pathways associated with miRNA signatures. We conclude that TAs of extremely premature infants contain miRNA signatures associated with severe BPD. These may serve as potential biomarkers of disease severity in infants with BPD.

DNMT1-mediated lncRNA MEG3 methylation accelerates endothelial-mesenchymal transition in diabetic retinopathy through the PI3K/Akt/mTOR signaling pathway

Diabetic retinopathy (DR) is one of the serious complications that occurs in diabetic patients that frequently causes blindness. Long noncoding RNAs (lncRNAs) have been associated with DR pathology. This study aimed to determine the underlying mechanism of lncRNA maternally expressed gene 3 (MEG3) in association with DNA methyltransferase 1 (DNMT1) in the endothelial-mesenchymal transition (endMT) that occurs in DR. A rat model of DR was induced by streptozotocin (STZ) injection, and a high-glucose (HG)-induced cell model was established by exposing microvascular endothelial cells obtained from retina of rats to HG. Subsequently, MEG3 was overexpressed in rat and cell models to characterize its impact on endMT in DR and the involvement of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, the methylation level of MEG3 promoter region was determined with the application of methylation-specific polymerase chain reaction, followed by chromatin immunoprecipitation assay for methyltransferase enrichment. Finally, we examined the regulation of DNMT1 on MEG3 methylation and endMT in the HG-induced cell model. The results obtained revealed downregulated MEG3 expression in DR rat and cell models. Overexpressed MEG3 was shown to suppress endMT in DR rat and cell models through the inhibition of the PI3K/Akt/mTOR signaling pathway. Notably, DNMT1 could promote MEG3 promoter methylation to inhibit MEG3 expression by recruiting methyltransferase, which activated the PI3K/Akt/mTOR signaling pathway to accelerate endMT in DR. These findings further highlighted the inhibitory effect of MEG3 on endMT in DR, thus presenting a novel therapeutic target candidate for DR treatment.

Hypermethylation-mediated downregulation of long non-coding RNA MEG3 inhibits osteogenic differentiation of bone marrow mesenchymal stem cells and promotes pediatric aplastic anemia

BACKGROUND

The reduced osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is the typical characteristics of pediatric aplastic anemia (AA) pathogenesis. Long non-coding RNA MEG3 is reported to promote osteogenic differentiation of BMSCs via inducing BMP4 expression.

OBJECTIVE

This study aims to investigate the mechanism of DNMT1/MEG3/BMP4 pathway in osteogenic differentiation of BMSCs in pediatric AA.

METHODS

BMSCs were isolated and purified from bone marrows of pediatric AA patients (n = 5) and non-AA patients (n = 5). The expression of DNMT1, MEG3, and BMP4 in isolated BMSCs was detected using quantitative real-time PCR and western blot analysis. Osteogenic differentiation was determined using Alizarin red staining. The methylation of MEG3 promoter and the interaction between DNMT1 and MEG3 promoter were detected using methylation-specific PCR and chromatin immunoprecipitation assay, respectively.

RESULTS

Lowly expressed MEG3 and BMP4 and highly expressed DNMT1 were observed in BMSCs of pediatric AA patients. The overexpression of MEG3 promoted osteogenic differentiation of BMSCs. Luciferase reporter assay showed that MEG3 overexpression increased transcriptional activity of BMP4. The inhibitor of methylation, 5-azacytidine, suppressed DNMT1 expression and reduced methylation of MEG3 promoter. Overexpression of DNMT1 increased the binding between DNMT1 and MEG3 promoter. The simultaneous overexpression of DNMT1 and MEG3 restored the inhibition of osteogenic differentiation caused by DNMT1 overexpression alone.

CONCLUSIONS

Our findings indicated that DNMT1 mediated the hypermethylation of MEG3 promoter in BMSCs, and DNMT1/MEG3/BMP4 pathway modulated osteogenic differentiation of BMSCs in pediatric AA.

MiR-185-5p ameliorates endoplasmic reticulum stress and renal fibrosis by downregulation of ATF6

Endoplasmic reticulum (ER) stress is considered an important factor in the formation of fibrosis. Therefore, modulation of ER stress may represent a promising therapeutic strategy in renal fibrosis. MiR-185-5p has been identified to be implicated in TGF-β1-induced renal fibrosis; however, it is largely unknown whether and how miR-185-5p regulates ER stress in renal fibrosis. In this study, we demonstrated that miR-185-5p directly bound to ATF6, an ER stress-related protein, and downregulated the expression thereof. We subsequently constructed an in vitro model of renal fibrosis using HK2 cells treated with TGF-β1, and found that miR-185-5p attenuated ER stress and dedifferentiation of tubular epithelia by suppression of ATF6. In addition, we constructed an in vivo mouse model using unilateral urethral obstruction (UUO). Our in vivo findings showed that miR-185-5p reduced the expression of ER stress-related proteins and inhibited epithelial dedifferentiation via downregulation of ATF6, thereby improving UUO-induced renal fibrosis. Overall, our findings revealed that miR-185-5p exerts beneficial effects in renal fibrosis. Thus, the miR-185-5p/ATF6 regulatory pathway may be a potential target for therapeutic intervention in renal fibrosis.

Collagen IV, a promising serum biomarker for evaluating the prognosis of revascularization in a 2-kidney, 1-clip hypertensive rat model

OBJECTIVES

The goal of this study was to investigate the expression of serum collagen IV and its value for evaluating the prognosis of revascularization in a 2-kidney, 1-clip hypertensive rat model.

METHODS

A total of 40 Sprague-Dawley rats were randomly and evenly divided into a control group and 3-, 10- and 20-day (D) groups (namely, the ischaemic time for 3, 10 and 20 days, respectively). The systolic blood pressure and laboratory values such as serum creatinine and collagen IV levels were measured before and after clipping the renal artery. Histological Masson staining and immunohistochemical staining of collagen IV were conducted in a kidney specimen from each group to assess the severity of renal fibrosis and the level of collagen IV expression.

RESULTS

After clipping, systolic blood pressure in the 3D, 10D and 20D groups increased significantly from 108 ± 8 to 126 ± 7 and from 153 ± 8 to 157 ± 6 mmHg, respectively (10D vs 20D group, P = 0.224; between other groups, P < 0.001). The expression of serum creatinine in the 3D, 10D and 20D groups increased significantly from 35.39 ± 5.64 to 57.53 ± 7.05, 101.86 ± 8.94 and 119.76 ± 9.37 mmol/l, respectively (between each group: P < 0.001). Serum collagen IV levels in the 10D and 20D groups increased significantly from 38.5 ± 10.4 to 60.8 ± 15.0 and 87.3 ± 11.5 ng/ml, respectively (control vs 3D group, P = 0.718; between other groups, P < 0.001). The Masson staining indicated that sclerotic changes in the glomeruli of the 10D and 20D groups significantly increased from 2.20 ± 1.03 to 15.20 ± 5.03 and 28.20 ± 7.07%, respectively (control vs 3D group, P = 0.175; between other groups, P < 0.001). The grade of tubulointerstitial damage in the 3D, 10D and 20D groups increased significantly from 0.30 ± 0.48 to 1.90 ± 0.74, 1.80 ± 0.79 and 3.20 ± 0.79, respectively (3D vs 10D group, P = 0.755; between other groups, P < 0.001). The semi-quantification from immunohistochemical staining indicated that the percentage of collagen IV positive areas in the 3D, 10D and 20D groups increased significantly from 3.50 ± 1.58 to 8.60 ± 2.11, 16.60 ± 8.55 and 23.10 ± 6.15, respectively (control vs 3D group, P = 0.043; 3D vs 10D group, P = 0.002; 10D vs 20D group, P = 0.011; between other groups, P < 0.001). The area under the curve of the receiver operating characteristic curve was 0.783 (P = 0.008; 95% confidence interval 0.634-0.932). There were positive associations of serum collagen IV levels with systolic blood pressure, serum creatinine and collagen IV quantification in kidney with correlation coefficients of 0.665, 0.775 and 0.628, respectively (P < 0.001).

CONCLUSIONS

As the clear ischaemia time-response relationship identified in our study indicates, the increase in serum collagen IV levels may be a satisfactory biomarker to indicate a poor prognosis of renal artery revascularization in a 2-kidney, 1-clip hypertensive rat model. However, it is perhaps not a good early biomarker for the early detection of renovascular hypertension.

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.

Emerging Roles of Long Non-Coding RNAs in Renal Fibrosis

Renal fibrosis is an unavoidable consequence that occurs in nearly all of the nephropathies. It is characterized by a superabundant deposition and accumulation of extracellular matrix (ECM). All compartments in the kidney can be affected, including interstitium, glomeruli, vasculature, and other connective tissue, during the pathogenesis of renal fibrosis. The development of this process eventually causes destruction of renal parenchyma and end-stage renal failure, which is a devastating disease that requires renal replacement therapies. Recently, long non-coding RNAs (lncRNAs) have been emerging as key regulators governing gene expression and affecting various biological processes. These versatile roles include transcriptional regulation, organization of nuclear domains, and the regulation of RNA molecules or proteins. Current evidence proposes the involvement of lncRNAs in the pathologic process of kidney fibrosis. In this review, the biological relevance of lncRNAs in renal fibrosis will be clarified as important novel regulators and potential therapeutic targets. The biology, and subsequently the current understanding, of lncRNAs in renal fibrosis are demonstrated—highlighting the involvement of lncRNAs in kidney cell function, phenotype transition, and vascular damage and rarefaction. Finally, we discuss challenges and future prospects of lncRNAs in diagnostic markers and potential therapeutic targets, hoping to further inspire the management of renal fibrosis.

Synergistic antifibrotic effects of miR-451 with miR-185 partly by co-targeting EphB2 on hepatic stellate cells

Liver fibrosis is a global health problem currently without clinically approved drugs. It is characterized by the excessive accumulation of extracellular matrix (ECM) mainly produced by activated hepatic stellate cells (HSCs). Uncovering the mechanisms underlying the fibrogenic responses in HSCs may have profound translational implications. Erythropoietin-producing hepatocellular receptor B2 (EphB2) is a receptor tyrosine kinase that has been indicated to be a novel profibrotic factor involved in liver fibrogenesis. In the present study, we investigated the effects of miR-451 and miR-185 on the expression of EphB2 and their roles in liver fibrogenesis both in vitro and in vivo. We found that EphB2 upregulation is a direct downstream molecular event of decreased expression of miR-451 and miR-185 in the process of liver fibrosis. Moreover, miR-451 was unexpectedly found to upregulate miR-185 expression at the post-transcriptional level by directly targeting the nuclear export receptor exportin 1 (XPO-1) and synergistically suppress HSCs activation with miR-185. To investigate the clinical potential of these miRNAs, miR-451/miR-185 agomirs were injected individually or jointly into CCl4-treated mice. The results showed that coadministration of these agomirs synergistically alleviated liver fibrosis in vivo. These findings indicate that miR-451 and miR-451/XPO-1/miR-185 axis play important and synergistic regulatory roles in hepatic fibrosis partly through co-targeting EphB2, which provides a novel therapeutic strategy for the treatment of hepatic fibrosis.

m6A-induced lncRNA MALAT1 aggravates renal fibrogenesis in obstructive nephropathy through the miR-145/FAK pathway

Renal fibrosis is a key factor in chronic kidney disease (CKD). Long non-coding RNAs (lncRNAs) play important roles in the physiological and pathological progression of human diseases. However, the roles and underlying mechanisms of lncRNAs in renal fibrosis still need to be discovered. In this study, we first displayed the increased lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) expression in renal fibrosis in patients with obstructive nephropathy (ON). Then we found that transforming growth factor beta 1 (TGF-β1) induced epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) protein deposition, which promoted the viability, proliferation and migration of human renal proximal tubular epithelial (HK2) cells. Next, MALAT1/miR-145/focal adhesion kinase (FAK) pathway was confirmed to play an importment role in TGF-β1-induced renal fibrosis. In addition, the MALAT1/miR-145/FAK pathway was involved in the effect of dihydroartemisinin (DHA) on TGF-β1-induced renal fibrosis in vitro and in vivo. Furthermore, m⁶A methyltransferase methyltransferase-like 3 (METTL3) was shown to be the main methyltransferase of m⁶A modification on MALAT1.

[Expression of kinesin KIF3A in the kidney of mice with unilateral ureteral obstruction]

OBJECTIVE

To investigate the expression of KIF3A in mice with unilateral ureteral obstruction (UUO) and TGF-β1-induced NRK-52E cells and the role of KIF3A in renal tubular epithelial cell transdifferentiation.

METHODS

Thirty-six C57BL/6J mice were randomly divided into the sham group (n=18) and UUO group (n=18). Six mice in each group were sacrificed at 7, 14 and 21days after the operation. The degree of renal tubulointerstitial fibrosis of the mice was observed by HE staining, Masson trichrome staining and Sirius red staining. The expression and distribution of KIF3A in the kidney of the mice was detected using RT-PCR, Western blotting and immunohistochemistry. Western blotting was used to detect the expression of KIF3A, E-cadherin and α-SMA proteins in the renal tissue of the mice. The expressions of KIF3A, E-cadherin, α-SMA, Wnt4 and β-catenin proteins in NRK-52E cells with TGF-β1-induced transdifferentiation were detected by Western blotting.

RESULTS

Compared with the sham-operated mice, the mice with UUO showed worsened renal interstitial fibrosis with the increase of obstruction time, indicating successful modeling. The expressions of KIF3A mRNA and protein increased progressively and reached the peaked level at 21 days after UUO. The expression of α-SMA protein was significantly increased while E-cadherin protein expression was significantly reduced after UUO. The transdifferentiated NRK-52E cells showed significantly increased expressions of KIF3A (P < 0.001), Wnt4 (P < 0.05) and β-catenin proteins (P < 0.0001).

CONCLUSIONS

KIF3A may participate in the development of renal fibrosis through epithelial-mesenchymal transition mediated by wnt/β-catenin signaling pathway.

Emerging role of miRNAs in renal fibrosis

As one type of the most common endogenous short noncoding RNAs (ncRNAs), microRNAs (miRNAs) act as posttranscriptional regulators of gene expression and have great potential biological functions in the physiological and pathological processes of various diseases. The role of miRNAs in renal fibrosis has also attracted great attention in the previous 20 years, and new therapeutic strategies targeting miRNAs appear to be promising. Some researchers have previously reviewed the roles of miRNA in renal fibrosis disease, but numerous studies have emerged over the recent 5 years. It is necessary to update and summarize research progress in miRNAs in renal fibrosis. Thus, in this review, we summarize progress in miRNA-mediated renal fibrosis over the last 5 years and evaluate the biological functions of some miRNAs in different stages of renal fibrosis. Furthermore, we also expound the recent clinical applications of these miRNAs to provide new insights into the treatment of renal fibrosis disease.

TGF-β/Smad and Renal Fibrosis

Renal fibrosis is characterized by excessive deposition of extracellular matrix (ECM) that disrupts and replaces functional parenchyma, which leads to organ failure. It is known as the major pathological mechanism of chronic kidney disease (CKD). Although CKD has an impact on no less than 10% of the world population, therapeutic options are still limited. Regardless of etiology, elevated TGF-β levels are highly correlated with the activated pro-fibrotic pathways and disease progression. TGF-β, the key driver of renal fibrosis, is involved in a dynamic pathophysiological process that leads to CKD and end-stage renal disease (ESRD). It is becoming clear that epigenetics regulates renal programming, and therefore, the development and progression of renal disease. Indeed, recent evidence shows TGF-β1/Smad signaling regulates renal fibrosis via epigenetic-correlated mechanisms. This review focuses on the function of TGF-β/Smads in renal fibrogenesis, and the role of epigenetics as a regulator of pro-fibrotic gene expression.

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.

MEG3: an Oncogenic Long Non-coding RNA in Different Cancers

Long noncoding RNAs (lncRNAs) have recently considered as central regulators in diverse biological processes and emerged as vital players controlling tumorigenesis. Several lncRNAs can be classified into oncogenes and tumor suppressor genes depending on their function in cancer. A maternally expressed gene 3 (MEG3) gene transcripts a 1.6 kb lncRNA whose act as an antitumor component in different cancer cells, such as breast, liver, glioma, colorectal, cervical, gastric, lung, ovarian and osteosarcoma cancer cells. The present review highlights biological function of MEG3 to repress tumor through regulating the major tumor suppressor genes p53 and Rb, inhibiting angiogenesis-related factor, or controlling miRNAs. On the other hand, previous studies have also suggested that MEG3 mediates epithelial-mesenchymal transition (EMT). However, deregulation of MEG3 is associated with the  development and progression of cancer, suggesting that MEG3 may function as a potential biomarker and therapeutic target for human cancers.