Long noncoding RNA ENSRNOG00000037522 is involved in the podocyte epithelial‑mesenchymal transition in diabetic rats

QiHuangYiShen Granules Modulate the Expression of LncRNA MALAT1 and Attenuate Epithelial-Mesenchymal Transition in Kidney of Diabetic Nephropathy Rats

Background

QiHuangYiShen granules (QHYS), a traditional Chinese herbal medicine formula, have been used in clinical practice for treating diabetic kidney disease for several years by our team. The efficacy of reducing proteinuria and delaying the decline of renal function of QHYS has been proved by our previous studies. However, the exact mechanism by which QHYS exerts its renoprotection remains largely unknown. Emerging evidence suggests that lncRNA MALAT1 is abnormally expressed in diabetic nephropathy (DN) and can attenuate renal fibrosis by modulating podocyte epithelial-mesenchymal transition (EMT).

Objective

In the present study, we aimed to explore whether QHYS could modulate lncRNA MALAT1 expression and attenuate the podocyte EMT as well as the potential mechanism related to the Wnt/β-catenin signal pathway.

Methods

SD rats were fed with the high-fat-high-sucrose diet for 8 weeks and thereafter administered with 30 mg/kg streptozotocin intraperitoneally to replicate the DN model. Quality control of QHYS was performed using high-performance liquid chromatography. QHYS were orally administered at 1.25, 2.5, and 5 g/kg doses, respectively, to the DN model rats for 12 weeks. Body weight, glycated haemoglobin, blood urea nitrogen, serum creatinine, 24-h proteinuria, and kidney index were measured. The morphologic pathology of the kidney was evaluated by Hematoxylin-eosin and Masson's trichrome staining. The expression level of lncRNA MALAT1 was determined by quantitative real-time polymerase chain reaction. In addition, the expression levels of podocyte EMT protein markers and Wnt/β-catenin pathway proteins in renal tissues were evaluated by Western blotting and immunohistochemistry.

Results

The results showed that QHYS significantly reduced 24-h proteinuria, blood urea nitrogen, kidney index, and ameliorated glomerular hypertrophy and collagen fiber deposition in the kidney of DN rats. Importantly, QHYS significantly downregulated the expression level of lncRNA MALAT1, upregulated the expression of nephrin, the podocyte marker protein, downregulated the expression of desmin and FSP-1, and mesenchymal cell markers. Furthermore, QHYS significantly downregulated the expression levels of Wnt1, β-catenin, and active β-catenin.

Conclusion

Conclusively, our study revealed that QHYS significantly reduced proteinuria, alleviated renal fibrosis, and attenuated the podocyte EMT in DN rats, which may be associated with the downregulation of lncRNA MALAT1 expression and inhibition of the Wnt/β-catenin pathway.

Circulating expression and clinical significance of LncRNA ANRIL in diabetic kidney disease

BACKGROUND

Long noncoding RNA ANRIL has been found to be involved in the pathogenesis of diabetic kidney disease (DKD) and is expected to be a new target for prevention of DKD. However, the circulating expression and clinical significance of ANRIL in DKD patients is uncertain. This study aims to explore this issue.

METHODS

The study consisted of 20 healthy controls, 22 T2DM patients (normalbuminuria) and 66 DKD patients (grouped as follows: microalbuminuria, n = 23; macroalbuminuria, n = 22 and renal dysfunction, n = 21). The expressions of ANRIL in peripheral whole blood of all participants were measured by RT-qPCR.

RESULTS

The expression of ANRIL was significantly up-regulated in DKD patients (microalbuminuria, macroalbuminuria and renal dysfunction groups) than that in healthy control group. ANRIL was also over-expressed in macroalbuminuria and renal dysfunction groups in comparison with normalbuminuria group. ANRIL expression was positively correlated with Scr, BUN, CysC, urine β2-MG and urine α1-MG; while negatively correlated with eGFR in DKD patients. In addition, ANRIL was the risk factor for DKD with OR value of 1.681. The AUC of ANRIL in identifying DKD was 0.922, and the sensitivity and specificity of DKD diagnosis were 83.3% and 90.5%, respectively.

CONCLUSION

Our results indicated that highly expressed ANRIL in peripheral blood is associated with progression of DKD. Circulating ANRIL is an independent risk factor of DKD and has a highly predictive value in identifying DKD.

Paeoniflorin directly binds to TNFR1 to regulate podocyte necroptosis in diabetic kidney disease

Necroptosis was elevated in both tubulointerstitial and glomerular renal tissue in patients with diabetic kidney disease (DKD), and was most pronounced on glomerulus in the stage with macroalbuminuria. This study further explored whether paeoniflorin (PF) could affect podocyte necroptosis to protect kidney injure in vivo and in vitro. Our study firstly verified that there are obvious necroptosis-related changes in the glomeruli of DKD through bioinformatics analysis combined with clinicopathological data. STZ-induced mouse diabetes model and high-glucose induced podocyte injury model were used to evaluate the renoprotection, podocyte injury protection and necroptosis regulation of PF in DKD. Subsequently, the target protein-TNFR1 that PF acted on podocytes was found by computer target prediction, and then molecular docking and Surface plasmon resonance (SPR) experiments were performed to verify that PF had the ability to directly bind to TNFR1 protein. Finally, knockdown of TNFR1 on podocytes in vitro verified that PF mainly regulated the programmed necrosis of podocytes induced by high glucose through TNFR1. In conclusion, PF can directly bind and promote the degradation of TNFR1 in podocytes and then regulate the RIPK1/RIPK3 signaling pathway to affect necroptosis, thus preventing podocyte injury in DKD. Thus, TNFR1 may be used as a new potential target to treat DKD.

Microtubule associated protein 4 phosphorylation-induced epithelial-to-mesenchymal transition of podocyte leads to proteinuria in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) involves various structural and functional changes because of chronic glycemic assault and kidney failure. Proteinuria is an early clinical manifestation of DN, but the associated pathogenesis remains elusive. This study aimed to investigate the role of microtubule associated protein 4 (MAP4) phosphorylation (p-MAP4) in proteinuria in DN and its possible mechanisms.

METHODS

In this study, the urine samples of diabetic patients and kidney tissues of streptozotocin (STZ)-induced diabetic mice were obtained to detect changes of p-MAP4. A murine model of hyperphosphorylated MAP4 was established to examine the effect of MAP4 phosphorylation in DN. Podocyte was applied to explore changes of kidney phenotypes and potential mechanisms with multiple methods.

RESULTS

Our results demonstrated elevated content of p-MAP4 in diabetic patients' urine samples, and increased kidney p-MAP4 in streptozocin (STZ)-induced diabetic mice. Moreover, p-MAP4 triggered proteinuria with aging in mice, and induced epithelial-to-mesenchymal transition (EMT) and apoptosis in podocytes. Additionally, p-MAP4 mice were much more susceptible to STZ treatment and showed robust DN pathology as compared to wild-type mice. In vitro study revealed high glucose (HG) triggered elevation of p-MAP4, rearrangement of microtubules and F-actin filaments with enhanced cell permeability, accompanied with dedifferentiation and apoptosis of podocytes. These effects were significantly reinforced by MAP4 hyperphosphorylation, and were rectified by MAP4 dephosphorylation. Notably, pretreatment of p38/MAPK inhibitor SB203580 reinstated all HG-induced pathological alterations.

CONCLUSIONS

The findings indicated a novel role for p-MAP4 in causing proteinuria in DN. Our results indicated the therapeutic potential of MAP4 in protecting against proteinuria and related diseases. Video Abstract.

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.

Danggui buxue tang inhibited mesangial cell proliferation and extracellular matrix accumulation through GAS5/NF-κB pathway

Diabetic nephropathy (DN) is the common complications of diabetes mellitus, but the efficacy of available treatments for the prevention of DN is still unsatisfactory. In the present study, we aimed to explore the effect of Danggui buxue tang (DGT) on the proliferation of high glucose (HG)-induced mesangial cells and accumulation of extracellular matrix in mesangial cells. We found DGT up-regulated the expression of growth arrest specific transcript 5 (GAS5) and IκB kinase (IKK) dose-dependently in mouse mesangial cells (SV40 MES-13). We found DGT regulated the expression IKK and the activity of nuclear transcription factor-κB (NF-κB) via GAS5, and proved that long non-coding RNA (lncRNA) GAS5 was positively related with IKK. And we proved GAS5 regulated the expression of IKK and the activity of NF-κB. In addition, DGT inhibited the viability of MES-13 cells and extracellular matrix-related proteins (laminin (LN), fibronectin (FN) and collagen IV (Col IV)) via GAS5. Moreover, we proved GAS5 regulated the viability of SV40 MES-13 cells and extracellular matrix-related proteins through NF-κB pathway. DGT inhibited the proliferation of mesangial cells and accumulation of extracellular matrix via GAS5/NF-κB, therefore, DGT could be an effective treatment for the prevention of DN.

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.

Fibroblast Growth Factor 21 Attenuates Diabetes-Induced Renal Fibrosis by Negatively Regulating TGF-β-p53-Smad2/3-Mediated Epithelial-to-Mesenchymal Transition via Activation of AKT

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is required for renal fibrosis, which is a characteristic of diabetic nephropathy (DN). Our previous study demonstrated that fibroblast growth factor 21 (FGF21) prevented DN associated with the suppressing renal connective tissue growth factor expression, a key marker of renal fibrosis. Therefore, the effects of FGF21 on renal fibrosis in a DN mouse model and the underlying mechanisms were investigated in this study.

METHODS

Type 1 diabetes mellitus was induced in C57BL/6J mice by intraperitoneal injections of multiple low doses of streptozotocin. Then, diabetic and non-diabetic mice were treated with or without FGF21 in the presence of pifithrin-α (p53 inhibitor) or 10-[4'-(N,N-Diethylamino)butyl]-2-chlorophenoxazine hydrochloride (10-DEBC) hydrochloride (Akt inhibitor) for 4 months.

RESULTS

DN was diagnosed by renal dysfunction, hypertrophy, tubulointerstitial lesions, and glomerulosclerosis associated with severe fibrosis, all of which were prevented by FGF21. FGF21 also suppressed the diabetes-induced renal EMT in DN mice by negatively regulating transforming growth factor beta (TGF-β)-induced nuclear translocation of Smad2/3, which is required for the transcription of multiple fibrotic genes. The mechanistic studies showed that FGF21 attenuated nuclear translocation of Smad2/3 by inhibiting renal activity of its conjugated protein p53, which carries Smad2/3 into the nucleus. Moreover pifithrin-α inhibited the FGF21-induced preventive effects on the renal EMT and subsequent renal fibrosis in DN mice. In addition, 10-DEBC also blocked FGF21-induced inhibition of renal p53 activity by phosphorylation of mouse double minute-2 homolog (MDM2).

CONCLUSION

FGF21 prevents renal fibrosis via negative regulation of the TGF-β/Smad2/3-mediated EMT process by activation of the Akt/MDM2/p53 signaling pathway.

Jixuepaidu Tang-1 inhibits epithelial-mesenchymal transition and alleviates renal damage in DN mice through suppressing long non-coding RNA LOC498759

Jixuepaidu Tang-1 is obtained from the decoction of the Chinese traditional medicinal plants including Centella asiatica, Astragalus membranaceus, and Sanguis draconis. Transforming growth factor-β1 (TGF-β1)/serum- and glucocorticoid-inducible kinase-1 (SGK1)-induced epithelial-mesenchymal transition (EMT) plays a pivotal role in the pathogenesis of diabetic nephropathy (DN). In addition, long non-coding RNAs (lnRNAs) participate in the development of DN, but the role of lncRNA LOC498759 in DN is still unclear. This study aims to investigate the role of Jixuepaidu Tang-1 in regulating podocyte injury and renal damage in DN and to validate whether the mechanisms involve TGF-β1/SGK1 signaling and LOC498759. The drug treatment was initiated 2 weeks after the DN modeling. The MTT method and TUNEL staining were used to measure cell viability and apoptosis, respectively. Immunofluorescence staining was used to detect the expression of nephrin and desmin in podocytes. Sera from the Jixuepaidu Tang-1-treated mice reversed the high glucose (HG)-induced podocyte injury and EMT in mouse podocytes. Further in vivo assay revealed that Jixuepaidu Tang-1 not only reduced the ratio of the kidney to body weight, 24 h-urine total protein, and blood glucose, but alleviated glomerular mesangial extracellular matrix deposition and glomerular cell apoptosis in the streptozotocin-induced DN mice. Mechanically, the mechanisms of Jixuepaidu Tang-1 may involve the suppression of EMT by inhibiting the TGF-β1/SGK1-induced LOC498759 expression. Collectively, Jixuepaidu Tang-1 attenuates podocyte injury and renal damage in DN, and inhibits EMT through suppressing TGF-β1/SGK1-LOC498759 signaling.

The inhibition of SGK1 suppresses epithelial-mesenchymal transition and promotes renal tubular epithelial cell autophagy in diabetic nephropathy

Diabetic nephropathy (DN) is a common complication of diabetes that is the dominant cause of end-stage renal disease. However, the pathological mechanism of DN is yet to be elucidated. Serum and glucocorticoid induced kinase (SGK) 1, a ubiquitously expressed kinase, was employed in the current study to assess its effect on DN in vivo and in vitro. Male BALB/C mice and a human tubular epithelial cell line (HK-2) were utilized for experimentation. Male BALB/C mice and a human tubular epithelial cell line (HK-2) were utilized for experimentation. Pathological changes were measured via HE and staining and immunohistochemistry was performed to measure the expression of SGK 1. An SGK1 inhibitor, GSK650394, was applied to analyze the role of SGK1 in HK-2 cell epithelial-mesenchymal transition (EMT). Associated protein expressions were assessed via western blotting. In addition, migration was measured using a scratch wound healing assay. 3-methyladenine (3-MA), an autophagy inhibitor, was used to determine the variation of autophagy following SGK1 inhibition. The expression of autophagy proteins were analyzed. Furthermore, the expression of PI3K, AKT, mTOR and their levels of phosphorylation were measured. The results revealed that the ultrastructure of renal tissue suffered damage and that the expression of SGK1 was markedly increased. After SGK1 inhibition, HK-2 cell EMT was suppressed and cell migration was attenuated. Furthermore, the autophagy of HK-2 cells was promoted, an increased expression of Beclin-1 and LC3 II was detected, and a decreased expression of p62 was observed. Additionally, the phosphorylation of PI3K, AKT and mTOR were markedly upregulated. The results indicated that blocking autophagy signaling via 3-MA muted SGK1-protected against HG-evoked cell injury. Our study demonstrated that SGK1 inhibition promoted autophagy and suppressed renal tubular epithelial cell EMT in DN, indicating that SGK1 may serve as a potential therapeutic target of DN.

Epigenetic Risk Profile of Diabetic Kidney Disease in High-Risk Populations

PURPOSE OF REVIEW

Epigenetic variations have been shown to reveal vulnerability to diabetes and its complications. Although it has become clear that metabolic derangements, especially hyperglycemia, can impose a long-term metabolic memory that predisposes to diabetic complications, the underlying mechanisms remain to be understood. It has been suggested that epigenetics (e.g., histone modification, DNA methylation, and non-coding RNAs) help link metabolic disruption to aberrancies related to diabetic kidney disease (DKD). In this review, we discuss the key findings and advances made in the epigenetic risk profile of DKD and provide perspectives on the emerging topics that implicate epigenetics in DKD.

RECENT FINDINGS

Epigenetic profiles can be profoundly altered in patients with diabetes, in circulating blood cells as well as in renal tissues. These changes provide useful insight into the mechanisms of diabetic kidney injury and progressive kidney dysfunction. Increasing evidence supports the role of epigenetic regulation in DKD. More studies are needed to elucidate the mechanism and importance of epigenetic changes in the initiation and progression of DKD and to further explore their diagnostic and therapeutic potential in the clinical management of patients with diabetes who have a high risk for DKD.

The long noncoding RNA LOC105374325 causes podocyte injury in individuals with focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a common kidney disease that results in nephrotic syndrome. FSGS arises from dysfunction and apoptosis of podocytes in the glomerulus of the kidney, leading to podocytopathy. The molecular mechanisms underlying podocyte apoptosis remain incompletely understood. Using an array of gene expression profiling, PCR, and in situ hybridization assay, we found here that the levels of the long noncoding RNA LOC105374325 were elevated in the renal podocytes of individuals with FSGS. We also observed that the microRNAs miR-34c and miR-196a/b down-regulated the expression of the apoptosis regulators BCL2-associated X, apoptosis regulator (Bax), and BCL2 antagonist/killer 1 (Bak) in podocytes. Competitive binding between LOC105374325 and miR-34c or miR-196a/b increased Bax and Bak levels and caused podocyte apoptosis. Of note, the mitogen-activated protein kinase P38 and the transcription factor CCAAT enhancer-binding protein β (C/EBPβ) up-regulated LOC105374325 expression. P38 inhibition or C/EBPβ silencing decreased LOC105374325 levels and inhibited apoptosis in adriamycin-treated podocytes. LOC105374325 overexpression decreased miR-34c and miR-196a/b levels, increased Bax and Bak levels, and induced proteinuria and focal segmental lesions in mice. In conclusion, activation of the P38/C/EBPβ pathway stimulates the expression of LOC105374325, which, in turn, increases Bax and Bak levels and causes apoptosis by competitively binding to miR-34c and miR-196a/b in the podocytes of individuals with FSGS.