High Glucose-induced Mesangial Cell Research Articles

A novel lncRNA TCONS_00071187 upregulated by activated GSK3β promotes high glucose-induced mesangial cell proliferation in the diabetic nephropathy.

Inhibiting mesangial cell proliferation is one of the strategies to control the early progression of diabetic nephropathy (DN). GSK3β is closely related to cell apoptosis as well as the development of DN, but whether it acts on the proliferation of mesangial cells is unclear. This study aimed to elucidate the role and mechanism of GSK3β-mediated lncRNA in high glucose-induced mesangial cell proliferation. HBZY-1 cells were used to establish the cell model of DN. The automatic cell counter was applied to assess cell proliferation. Flow cytometry was used to detect cell apoptosis and intracellular ROS levels. High-throughput transcriptomics sequencing was performed to detect the different expressions of long noncoding RNAs (lncRNAs) in the cell model of DN after knocking down the expression of GSK3β by the transfection of siRNA. The expression of RNA was detected by real-time PCR. In the cell model of DN using HBZY-1 cells, cell proliferation was enhanced accompanied by GSK3β activation and elevated apoptosis rate and reactive oxygen species (ROS) levels. A panel of novel lncRNAs, which were differentially expressed after GSK3β knockdown in the cell model of DN, were identified by high-throughput transcriptomics sequencing. Among them, the expression of TCONS_00071187 was upregulated under high glucose conditions while the knockdown of the GSK3β expression led to the downregulation of TCONS_00071187. The knockdown of TCONS_00071187 resulted in reduced mesangial cell proliferation, and decreased apoptosis rates and ROS levels. In conclusion, GSK3β promoted mesangial cell proliferation by upregulating TCONS_00071187, which led to enhanced ROS production under high glucose conditions in the cell model of DN. This study revealed the role of GSK3β medicated lncRNAs in the development of DN.

Long non-coding RNA MEG3 silencing weakens high glucose-induced mesangial cell injury by decreasing LIN28B expression by sponging and sequestering miR-23c.

Diabetic nephropathy (DN) is a common kidney disease in diabetic patients. Long non-coding RNA maternally expressed gene 3 (MEG3) and microRNA (miR)-23c are reported to be implicated in DN development. Nevertheless, it is unclear that the molecular mechanism between MEG3 and miR-23c in DN remains unclear. Human mesangial cells (HMCs) were treated with high glucose (HG) to simulate the DN status in vitro. Expression of MEG3 and miR-23c was measured. Effects of MEG3 silencing on HG-stimulated HMC injury were determined. The relationship between MEG3 and miR-23c was verified by the dual-luciferase reporter and RNA immunoprecipitation assays. MEG3 was overexpressed in serums from DN patients and HG-stimulated HMCs. MEG3 knockdown weakened HG-stimulated HMC proliferation, extracellular matrix (ECM) accumulation, and inflammation. MEG3 regulated lin-28 homolog B (LIN28B) expression through adsorbing miR-23c. MiR-23c inhibitor reversed MEG3 knockdown-mediated effects on HG-stimulated HMC proliferation, ECM accumulation, and inflammation. LIN28B overexpression overturned miR-23c mimic-mediated effects on HG-stimulated HMC proliferation, ECM accumulation, and inflammation. MEG3 regulated HMC injury via regulation of the miR-23c/LIN28B axis in DN, which can help us better understand the mechanism of DN mediated by MEG3.

Long non‑coding RNA L13Rik promotes high glucose-induced mesangial cell hypertrophy and matrix protein expression by regulating miR-2861/CDKN1B axis.

Diabetic nephropathy (DN) is a frequent microvascular complication of diabetes. Glomerular mesangial cell (MC) hypertrophy occurs at the initial phase of DN and plays a critical role in the pathogenesis of DN. Given the role of long non coding RNA (lncRNA) in regulating MC hypertrophy and extracellular matrix (ECM) accumulation, our aim was to identify functional lncRNAs during MC hypertrophy. Here, an lncRNA, C920021L13Rik (L13Rik for short), was identified to be up-regulated in DN progression. The expression of L13Rik in DN patients and diabetic mice was assessed using quantitative real-time PCR (qRT-PCR), and the function of L13Rik in regulating HG-induced MC hypertrophy and ECM accumulation was assessed through flow cytometry and western blotting analysis. The L13Rik levels were significantly increased while the miR-2861 levels were decreased in the peripheral blood of DN patients, the renal tissues of diabetic mice, and HG-treated MCs. Functionally, both L13Rik depletion and miR-2861 overexpression effectively reduced HG-induced cell hypertrophy and ECM accumulation. Mechanistically, L13Rik functioned as a competing endogenous RNA (ceRNA) to sponge miR-2861, resulting in the de-repression of cyclin-dependent kinase inhibitor 1B (CDKN1B), a gene known to regulate cell cycle and MC hypertrophy. Collectively, the current results demonstrate that up-regulated L13Rik is correlated with DN and may be a hopeful therapeutic target for DN.

Circ_0123996 promotes the proliferation, inflammation, and fibrosis of mesangial cells by sponging miR-203a-3p to upregulate SOX6 in diabetic nephropathy.

Circular RNAhas been reported to participate in human diseases including diabetic nephropathy (DN). However, the role and mechanism of circ_0123996 in DN need to be further explored. Relative expression levels of circ_0123996, microRNA (miR)-203a-3p, SRY-box 6 (SOX6), and inflammatory cytokines were determined using quantitative real-time PCR. Western blot analysis was used to detect the protein expression of SOX6 and fibrosis-related markers. Cell proliferation was measured using the Cell Counting Kit 8assay. The interaction between miR-203a-3p and circ_0123996 or SOX6 was verified using the dual-luciferase reporter assay. The circ_0123996 and SOX6 expression wereincreased and the miR-203a-3p expression was decreased in high glucose-induced mesangial cells. Silenced circ_0123996 could hinder the proliferation, inflammation, and fibrosis of mesangial cells. In terms of mechanism, circ_0123996 could sponge miR-203a-3p to positively regulate SOX6 expression. Function experiments revealed that miR-203a-3p inhibitor could abolish the regulation of circ_0123996 silencing on mesangial cell proliferation, inflammation, and fibrosis. In addition, the knockdown of SOX6 could inhibit mesangial cell proliferation, inflammation, and fibrosis. Also, SOX6 overexpression could reverse the regulation of circ_0123996 silencing on mesangial cell progression. In summary, our data revealed that circ_0123996 promoted the proliferation, inflammation, and fibrosis of mesangial cells via modulating the miR-203a-3p/SOX6 axis, suggesting that circ_0123996 might be a target for alleviating DN progression.

LncRNA HOTAIR facilitates high glucose-induced mesangial cell proliferation, fibrosis and oxidative stress in diabetic nephropathy via regulating miR-147a/WNT2B axis

BackgroundLong non-coding RNAs (lncRNAs) have been shown to be involved in the regulation of many disease progression. However, the role of lncRNA HOX transcript antisense RNA (HOTAIR) in diabetic nephropathy (DN) remains unclear.MethodsHigh glucose (HG)-induced human mesangial cells (HMC) was used to construct DN cell models in vitro. HMC proliferation was evaluated by CCK8 assay and EDU staining. Protein levels of proliferation markers, fibrosis markers, and wingless-type family member 2B (WNT2B) were measured using western blot analysis. HMC oxidative stress was assessed by determining the levels of oxygen species and malondialdehyde, as well as superoxide dismutase activity. Relative expression levels of lncRNA HOTAIR, microRNA (miR)-147a, and WNT2B were examined using quantitative real-time PCR. The interaction between miR-147a and lncRNA HOTAIR or WNT2B was confirmed by dual-luciferase reporter assay and RIP assay.ResultsOur data showed that lncRNA HOTAIR knockdown could inhibit the proliferation, fibrosis, and oxidative stress in HG-induced HMC. LncRNA HOTAIR could serve as a sponge of miR-147a. The inhibition effect of lncRNA HOTAIR silencing on the biological functions of HG-induced HMC could be reversed by miR-147a inhibitor. WNT2B was targeted by miR-147a, and its overexpression also overturned the suppressive effect of miR-147a on the proliferation, fibrosis, and oxidative stress of HG-induced HMC.ConclusionIn total, our research pointed out that lncRNA HOTAIR could mediate miR-147a/WNT2B axis to promote DN progression.

Exosomal hsa_circ_0125310 promotes cell proliferation and fibrosis in diabetic nephropathy via sponging miR-422a and targeting the IGF1R/p38 axis.

Diabetic nephropathy (DN) is still on the rise worldwide, and millions of patients have to be treated through dialysis or transplant because of kidney failure caused by DN. Recent reports have highlighted circRNAs in the treatment of DN. Herein, we aimed to investigate the mechanism by which high glucose‐induced exo‐circ_0125310 promotes diabetic nephropathy progression. circ_0125310 is highly expressed in diabetic nephropathy and exosomes isolated from high glucose‐induced mesangial cells (MCs). High glucose‐induced exosomes promote the proliferation and fibrosis of MCs. However, results showed that the effects of exosomes on MCs can be reversed by the knockdown of circ_0125310. miR‐422a, which targets IGF1R, was the direct target of circ_0125310. circ_0125310 regulated IGF1R/p38 axis by sponging miR‐422a. Exo‐circ_0125310 increased the luciferase activity of the WT‐IGF1R reporter in the dual‐luciferase reporter gene assays and upregulated the expression level of IGF1R and p38. Finally, in vivo research indicated that the overexpression of circ_0125310 promoted the diabetic nephropathy progression. Above results demonstrated that the high glucose‐induced exo‐circ_0125310 promoted cell proliferation and fibrosis in diabetic nephropathy via sponging miR‐422a and targeting the IGF1R/p38 axis.

Circ_0000491 Promotes Apoptosis, Inflammation, Oxidative Stress, and Fibrosis in High Glucose-Induced Mesangial Cells by Regulating miR-455-3p/Hmgb1 Axis

Background: Diabetic nephropathy (DN) is a severe microvascular complication of diabetes. Recently, many circular RNAs can exert crucial roles in DN progression. This study intended to explore the role and mechanism of circ_0000491 in DN. Methods: The DN mouse model was constructed by streptozotocin injection, and the DN cell model was established using high glucose (HG) treatment in mouse mesangial cells (SV40-MES13). The expression of circ_0000491 and microRNA-455-3p (miR-455-3p) was detected by quantitative real-time polymerase chain reaction. Cell apoptosis was evaluated by flow cytometry. The expression levels of high-mobility group box 1 (Hmgb1) protein, apoptosis-related proteins, and fibrosis-related proteins were examined by the Western blot assay. The release of inflammatory cytokines was assessed by enzyme-linked immunosorbent assay. The oxidative stress factors were analyzed by corresponding kits. The predicted interaction between miR-455-3p and circ_0000491 or Hmgb1 was verified by dual-luciferase reporter assay and RNA immunoprecipitation assay. Results: Circ_0000491 was overexpressed in the DN mouse model and HG-induced SV40-MES13 cells. Knockdown of circ_0000491 weakened HG-induced apoptosis, inflammation, oxidative stress, and fibrosis in SV40-MES13 cells. miR-455-3p was a direct target of circ_0000491, and miR-455-3p inhibition could reverse the role of circ_0000491 silencing in HG-induced SV40-MES13 cells. Moreover, Hmgb1 was a target gene of miR-455-3p, and miR-455-3p played a protective role against HG-induced cell injury by targeting Hmgb1. In addition, circ_0000491 regulated Hmgb1 expression by sponging miR-455-3p. Conclusion: Circ_0000491 knockdown inhibited HG-induced apoptosis, inflammation, oxidative stress, and fibrosis in SV40-MES13 cells by regulating miR-455-3p/Hmgb1 axis.

LncRNA NEAT1 Promotes High Glucose-Induced Mesangial Cell Hypertrophy by Targeting miR-222-3p/CDKN1B Axis.

Glomerular hypertrophy is an early morphological alteration in diabetic nephropathy. Cyclin-Dependent Kinases have been shown to be required for high glucose (HG)-induced hypertrophy; however, the upstream regulators of CDKN1B in glomerular hypertrophy remain unclear. Herein we describe a novel pathway in which Long noncoding RNA (lncRNA) NEAT1 regulates the progression of mesangial cell hypertrophy via a competing endogenous RNA (ceRNA) mechanism. Real-time PCR was performed to detect the relative NEAT1 and miR-222-3p expressions and further confirmed the relationship between NEAT1 and miR-222-3p. Cell cycle was evaluated by flow cytometry. The related mechanisms were explored by Western blot, RNA immunoprecipitation and chromatin immunoprecipitation assay. We show that NEAT1 forms double stranded RNA (dsRNA) with miR-222-3p, thus limiting miR-222-3p’s binding with CDKN1B. This release of CDKN1B mRNA leads to elevated CDKN1B protein expression, resulting in hypertrophy. In addition, we demonstrated that STAT3 which is activated by HG induces the transcription of NEAT1 by binding to its promoter. Our findings underscore an unexpected role of lncRNAs on gene regulation and introduce a new mode of proliferation regulation in mesangial cells.

Scopoletin and umbelliferone from Cortex Mori as protective agents in high glucose-induced mesangial cell as in vitro model of diabetic glomerulosclerosis.

Two known coumarins, scopoletin (SP) and umbelliferone (UB), were isolated from Cortex Mori (CM). Their structures were elucidated by various spectroscopic analyses. Then, their effects on rat glomerular mesangial cells (RGMCs, HBZY-1) proliferation, hypertrophy, extracellular matrix (ECM) proliferation, expression of fibronectin, transforming growth factor-beta (TGF-β), and connective tissue growth factor (CTGF) induced by high glucose were studied in vitro model of diabetic glomerulosclerosis. The results show that, CM, SP, and UB can inhibit the RGMCs proliferation to attenuate the ECM proliferation and cell hypertrophy, reduced the accumulation of ECM protein fibronectin, and lowered the expression of the key fibrosis factor TGF-β and CTGF to inhibit the kidney fibrosis and thereby improved diabetic glomerulosclerosis. The two coumarins show great potentialities on treating diabetic glomerulosclerosis, but the animal experiment and mechanism is strongly needed for further proof.

A protective role of renalase in diabetic nephropathy.

Renalase, a recently discovered secreted flavoprotein, exerts anti-apoptotic and anti-inflammatory effects against renal injury in acute and chronic animal models. However, whether Renalase elicits similar effects in the development of diabetic nephropathy (DN) remains unclear. The studies presented here tested the hypothesis that Renalase may play a key role in the development of DN and may have therapeutic potential for DN. Renalase expression was measured in human kidney biopsies with DN and in kidneys of db/db mice. The role of Renalase in the development of DN was examined using a genetically engineered mouse model: Renalase knockout mice with db/db background. The renoprotective effects of Renalase in DN was evaluated in db/db mice with Renalase overexpression. In addition, the effects of Renalase on high glucose-induced mesangial cells were investigated. Renalase was down-regulated in human diabetic kidneys and in kidneys of db/db mice compared with healthy controls or db/m mice. Renalase homozygous knockout increased arterial blood pressure significantly in db/db mice while heterozygous knockout did not. Renalase heterozygous knockout resulted in elevated albuminuria and increased renal mesangial expansion in db/db mice. Mesangial hypertrophy, renal inflammation, and pathological injury in diabetic Renalase heterozygous knockout mice were significantly exacerbated compared with wild-type littermates. Moreover, Renalase overexpression significantly ameliorated renal injury in db/db mice. Mechanistically, Renalase attenuated high glucose-induced profibrotic gene expression and p21 expression through inhibiting extracellular regulated protein kinases (ERK1/2). The present study suggested that Renalase protected against the progression of DN and might be a novel therapeutic target for the treatment of DN.

Farrerol alleviates high glucose-induced renal mesangial cell injury through the ROS/Nox4/ERK1/2 pathway

Hyperproliferation and oxidative stress induced by hyperglycemia in mesangial cells plays crucial roles in the pathological process of diabetic nephropathy. Farrerol, isolated from rhododendron leaves, possesses broad anti-oxidative and anti-inflammatory properties towards several diseases, but its role in diabetic neuropathy remains unclear. The aim of this study was to evaluate the effects of farrerol in high glucose induced mesangial cell injury, and to explore underlying molecular mechanisms. Our results showed that high glucose in vitro conditions significantly stimulated cell proliferation, inflammatory cytokine secretion, extracellular matrix deposition, excessive oxidative stress, and NADPH oxidase activity in mesangial cells. Levels of NADPH oxidase 4 (Nox4) expression, ERK1/2 phosphorylation, and TGF-β1/Smad2 activation were significantly induced by high glucose conditions in mesangial cells. Inversely, farrerol treatments at 40, 60, and 80 μM concentrations, dose-dependently alleviated this molecular damage by high glucose in mesangial cells. We also found that restoration of Nox4 expression abolished the protective effects of farrerol on high glucose-induced proliferation and reactive oxygen species generation. Furthermore, pretreatment with the Nox4 inhibitor diphenyliodonium or the ERK1/2 pathway inhibitor PD98059, displayed similar ameliorated effects of farrerol on high glucose-induced mesangial cell damage. Taken together, these data suggest that farrerol displays protective effects on high glucose induced mesangial cell injury, partly through the Nox4-mediated ROS/ERK1/2 signaling pathway. These observations may provide novel insights into the application of farrerol as a diabetic neuropathy treatment.

Metformin inhibits high glucose-induced mesangial cell proliferation, inflammation and ECM expression through the SIRT1-FOXO1-autophagy axis.

The aim of this study was to investigate the role of metformin in high glucose-induced mesangial cell proliferation, inflammation and extracellular matrix (ECM) accumulation and to elucidate the underlying mechanism of metformin function. An MTT assay was used to examine rat mesangial cell (RMC) proliferation. The levels of TNF-α, IL-6 and TGF-β in RMCs were determined by ELISA. The protein expression of fibronectin, collagen IV and autophagy-related proteins (Beclin-1, LC3-I and LC3-II) in RMCs was detected using western blot. Fluorescence microscopy analysis was carried out to evaluate RMC autophagy. Our results showed that high glucose-induced RMC proliferation, inflammation and ECM expression, but these effects were markedly reduced by metformin. We confirmed that metformin suppressed high glucose-induced RMC proliferation, inflammation and ECM expression via induction of autophagy. Mechanistic investigation demonstrated an axis of SIRT1-FOXO1 in RMC autophagy. Our data indicated that metformin inhibits high glucose-induced mesangial cell proliferation, inflammation and ECM expression through a SIRT1-FOXO1-autophagy axis.

495-P: Kidney May Regulate SGLT2-Dependent Glucose Reabsorption through Sweet Taste Receptors: Implications for Diabetes

Sodium-glucose cotransporter 2 (SGLT2) mediates 90% glucose reabsorption in kidney, and SGLT2 inhibitors have emerged as a novel oral antihyperglycaemic agents by selectively reducing renal reabsorption of glucose and sodium. Recent research has suggested that sweet taste receptors (STRs) are important participants of diabetes. However, it is unclear whether STRs regulate reabsorption of glucose via SGLT2 in the pathogenesis of diabetes. Therefore, we evaluated the role and mechanism of STRs in reabsorption of glucose via streptozotocin (STZ)-induced diabetes mouse in vivo and in high glucose-induced mouse glomerular mesangial cells (GMCs) and human proximal renal tubular epithelia cells (HK-2) in vitro. Our results showed that the expression of STRs were obviously downregulated while SGLT2 was upregulated under the condition of diabetes in vivo and in vitro. We hypothesized that high glucose-induced downregulation of STRs might modulate reabsorption of glucose. STRs inhibitor lactisole or siRNA-STRs was used as an intervention reagent respectively, distribution of STRs in vivo was detected by PET/CT via intravenous injection of 18F-labeled lactisole, glucose level, renal pathology and SGLT2 expression in vivo and fluorescence labeled glucose uptake rate in vitro were assayed. The effect of high glucose on STRs and SGLT2 expression as well as the glucose absorption were obviously mitigated by lactisole or siRNA-STRs. Overall, this is the first observation of the potential relationship between STRs and SGLT2, suggesting that kidney may regulate SGLT2-depended glucose reabsorption through STRs, which may act as new therapeutic targets of diabetes. Disclosure L. Zhou: None. W. Huang: None. N. Liu: None. X.M. Ma: None. M. Guo: None. Q. Chen: None. C. Gao: None. Y. Xu: None. Funding National Natural Science Foundation of China (81800741)

Deacetylation of S6 kinase promotes high glucose–induced glomerular mesangial cell hypertrophy and matrix protein accumulation

S6 kinase acts as a driver for renal hypertrophy and matrix accumulation, two key pathologic signatures of diabetic nephropathy. As a post-translational modification, S6 kinase undergoes acetylation at the C terminus. The role of this acetylation to regulate kidney glomerular cell hypertrophy and matrix expansion is not known. In mesangial cells, high glucose decreased the acetylation and enhanced phosphorylation of S6 kinase and its substrates rps6 and eEF2 kinase that lead to dephosphorylation of eEF2. To determine the mechanism of S6 kinase deacetylation, we found that trichostatin A, a pan-histone deacetylase (HDAC) inhibitor, blocked all high glucose-induced effects. Furthermore, high glucose increased the expression and association of HDAC1 with S6 kinase. HDAC1 decreased the acetylation of S6 kinase and mimicked the effects of high glucose, resulting in mesangial cell hypertrophy and expression of fibronectin and collagen I (α2). In contrast, siRNA against HDAC1 inhibited these effects by high glucose. A C-terminal acetylation-mimetic mutant of S6 kinase suppressed high glucose-stimulated phosphorylation of S6 kinase, rps6 and eEF2 kinase, and inhibited the dephosphorylation of eEF2. Also, the acetylation mimetic attenuated the mesangial cell hypertrophy and fibronectin and collagen I (α2) expression. Conversely, an S6 kinase acetylation-deficient mutant induced all the above effects of high glucose. Finally, in the renal glomeruli of diabetic rats, the acetylation of S6 kinase was significantly reduced concomitant with increased HDAC1 and S6 kinase activity. In aggregate, our data uncovered a previously unrecognized role of S6 kinase deacetylation in high glucose-induced mesangial cell hypertrophy and matrix protein expression.

Ergosterol Ameliorates Diabetic Nephropathy by Attenuating Mesangial Cell Proliferation and Extracellular Matrix Deposition via the TGF-β1/Smad2 Signaling Pathway.

(1) Background: Diabetic nephropathy, a microvascular complication of diabetes, is one of the principal causes of end-stage renal disease worldwide. The aim of this study was to explore the therapeutic effects of ergosterol on diabetic nephropathy. (2) Methods: Streptozotocin (STZ)-induced C57BL/6 diabetic mice were treated with ergosterol (10, 20, 40 mg/kg/day) for 8 weeks by oral gavage. The in vitro study employed rat mesangial cells exposed to 30 mM glucose for 48 h in the presence of 10 or 20 μM ergosterol. (3) Results: Ergosterol treatment improved body weights, ameliorated the majority of biochemical and renal functional parameters and histopathological changes, and reduced extracellular matrix (ECM) deposition in diabetic mice. In vitro, ergosterol suppressed proliferation, reduced the levels of ECM proteins, and increased the expression of matrix metalloproteinase-2 and -9 in high glucose-induced mesangial cells; Furthermore, ergosterol markedly improved transforming growth factor-β1 (TGF-β1) expression, enhanced phosphorylation levels of drosophila mothers against decapentaplegic 2 (Smad2), and regulated the downstream factors in vivo and in vitro. (4) Conclusions: Ergosterol alleviated mesangial cell proliferation and the subsequent ECM deposition by regulating the TGF-β1/Smad2 signaling pathway.

Long noncoding RNA NEAT1 accelerates the proliferation and fibrosis in diabetic nephropathy through activating Akt/mTOR signaling pathway.

Accumulating evidence has indicated the significant roles of long noncoding RNAs (lncRNAs) in the pathophysiology of diabetic nephropathy (DN). LncRNA nuclear enriched abundant transcript 1 (NEAT1) has been reported to exert a key role in the progression of several diseases including diabetes. However, the role of NEAT1 in the regulation of DP progression remains barely known. Therefore, our study aimed to investigate the role of NEAT1 in a streptozotocin-induced diabetes model (DM) of rats and glucose-induced mouse mesangial cell models. Currently, we found that NEAT1 was greatly upregulated in DM rats and glucose-induced mice mesangial cells, in which a high activation of Akt/mTOR signaling was also observed. Then, it was shown that knockdown of NETA1 was able to reduce renal injury in DM rats obviously. In addition, cell counting kit-8 assay and 5-ethynyl-2'-deoxyuridine assay were carried out and we observed downregulation of NEAT1 significantly inhibited mesangial cell proliferation. Meanwhile, extracellular matrix proteins and messenger RNA (transforming growth factor β1, fibronectin, and collagen IV) expression was dramatically restrained by silencing of NEAT1 in the high glucose-induced mesangial cells. Finally, knockdown of NEAT1 greatly reduced the expression of the phosphorylation of Akt and mammalian target of rapamycin (mTOR) in vitro. These findings revealed that the decrease of NEAT1 repressed the proliferation and fibrosis in DN via activating the Akt/mTOR signaling pathway, which might represent a novel pathological mechanism of DN progression.

Astragaloside IV represses high glucose-induced mesangial cells activation by enhancing autophagy via SIRT1 deacetylation of NF-κB p65 subunit.

AimMesangial cell (MC) activation plays an important role in many glomerular diseases associated with renal fibrosis, including diabetic kidney disease (DKD). The aim of this study was to determine whether Astragaloside IV (AS-IV) modulated MC activation in DKD via autophagy by specifically regulating the autophagy inducer sirtuin 1 (SIRT1).MethodsCultured MCs and diabetic KK-Ay mice were treated with AS-IV, and the markers and regulatory mediators of autophagy were analyzed using Western blotting, real-time PCR, ELISA and IF.ResultsAS-IV inhibited MC activation and enhanced autophagy in hyperglycemic conditions by increasing SIRT1 expression and decreasing NF-κB p65 acetylation. In addition, the SIRT1 activator SRT1720 enhanced autophagy and decreased p65 acetylation during hyperglycemia-induced MC activation. Opposite effects were seen with the SIRT1 inhibitor EX527. Furthermore, the ameliorative effect of AS-IV on MCs was abolished by the autophagy inhibitor 3-MA, while the autophagy activator rapamycin restored hyperglycemia-induced MC activation. Finally, AS-IV improved renal function and fibrosis in the diabetic KK-Ay mice.ConclusionAS-IV ameliorated renal function and morphology by inducing autophagy and inhibiting MC activation through the SIRT1-NF-κB pathway, indicating a potential therapeutic role of AS-IV in glomerular diseases.

Short-Chain Fatty Acids Prevent Diabetic Nephropathy In Vivo and In Vitro

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD). Over the past decade, the gut microbiota metabolites—short-chain fatty acids (SCFAs), have emerged as new therapeutic targets of systemic inflammatory diseases and kidney injury such as acute kidney injury (AKI) via GPRs-β-arrestins signaling pathway and histone deacetylase-inhibiting (HDACi) properties. However, it is unclear whether SCFAs might prevent DN. Therefore, we evaluated the role and mechanism of the three main SCFAs (acetate, propionate, and butyrate) in streptozotocin (STZ) and high-fat diet (HFD)-induced type 2 diabetes (T2D) and DN mouse model in vivo and in high glucose-induced mouse glomerular mesangial cells (GMCs) and human proximal renal tubular epithelia cells in vitro. Our results found that exogenous SCFAs administration, especially butyrate, protected from experimental T2D, preventing the renal dysfunction and inhibiting oxidative stress and NF-κB inflammatory signaling in vivo. The GPR43 expression decreased, however, β-arrestin-2 expression increased in both high glucose-stimulated renal intrinsic cells and in DN kidney tissue. We hypothesized that SCFAs-mediated GPR43-β-arrestin-2 signaling might modulate kidney injury. GPR43 was over-expressed or suppressed by transfection with a GPR43 expressing vector or siRNA-GPR43 respectively. Exogenous SCFAs-mediated the anti-oxidative stress and anti-inflammatory effects were significantly facilitated or imitated by over-expression GPR43 or GPR43 agonist, but which were inhibited by siRNA-GPR43. Specifically, co-IP revealed that butyrate regulated the interaction between I-κBα and β-arrestin-2 via GPR43. Overall, this is the first observation of the potential therapeutic role of SCFAs in DN, we demonstrated that SCFAs improved STZ and HFD-induced renal dysfunction and inhibited NF-κB activation through GPR43-β-arrestin-2 signaling, suggesting a likely mechanism for SCFAs-mediated therapeutic effect in DN. Disclosure W. Huang: None. Y. Xu: None. Y. Xu: None. L. Zhou: None. C. Gao: None.

Berberine attenuates podocytes injury caused by exosomes derived from high glucose-induced mesangial cells through TGFβ1-PI3K/AKT pathway

Diabetic nephropathy is the most common microvascular complications of diabetes. Berberine is the main active ingredient of Coptis chinensis and previous studies have been showed that berberine could delay the progression of diabetic nephropathy by regulating related cytokines and signaling pathways. Glomerular mesangial cells and podocytes are two vital indigenous cells of kidney and interaction between these two cellular components via exosomes might affect function of glomerulus in diabetic nephropathy condition. On the basis of our previous studies, transwell systems were used to demonstrate that the exosomes released by glomerular mesangial cells induced by the high glucose were involved in podocytes injury. The current study demonstrates that berberine can reduce TGFβ1 in exosomes released by high glucose-induced glomerular mesangial cells. Berberine-treated high glucose-induced exosomes which are secreted by glomerular mesangial cells can protect damage of podocytes by reducing apoptosis and increasing adhesion. These results suggest that berberine could protect the function of podocytes through inhibiting the transfer of TGFβ1 from the glomerular mesangial cells to the podocytes, which is one of the potential mechanisms of protective effect of berberine on diabetic nephropathy.

Scoparone attenuates high glucose-induced extracellular matrix accumulation in rat mesangial cells

Scoparone, a major constituent of Artemisia capillaries, has a variety of biological properties including anticoagulant, hepatoprotective, anti-tumor, anti-fibrosis, anti-inflammatory, antioxidant, and antidiabetic activities. However, the renoprotective effect of scoparone under diabetic conditions remains elusive. Thus, the present study was undertaken to examine the role of scoparone in high glucose-induced mesangial cell proliferation and extracellular matrix (ECM) accumulation and elucidate the possible mechanism of action of scoparone. Our results demonstrated that treatment with scoparone significantly inhibited the proliferation of mesangial cells under high glucose conditions. In addition, scoparone reversed high glucose-induced fibronectin and collagen IV expression in mesangial cells, as well as suppressed reactive oxygen species production and NOX2/4 expression in high glucose-exposed mesangial cells. Mechanistic studies revealed that scoparone prevented the activation of ERK1/2 signaling pathway in high glucose-exposed mesangial cells, and an ERK inhibitor (U0126) protected mesangial cells treated with high glucose. Taken together, these results demonstrated that scoparone protects mesangial cells against high glucose damage in part through the inactivation of ERK signaling pathway. These findings suggest that scoparone may represent a potential drug for the treatment of diabetic nephropathy.