Huaiqihuang (HQH) protects podocytes from high glucose-induced apoptosis and inflammation response by regulating PI3K/AKT/mTOR pathway.

Diabetic kidney disease (DKD) is one of the common microvascular complications of diabetes, and there are still lack of effective treatments. Huaiqihuang (HQH) is a kind of traditional Chinese medicine mixed preparation, which is mainly made of Trametes robiniophila Murr, Fructus Lycii, and Polygonatum sibiricumhas. It has been shown to be effective in the treatment of DKD, but the specific mechanism has not been fully elucidated. Our results showed that HQH increased the protein expressions of synaptopodin, podocin, WT-1, and Bcl-2, decreased the protein expressions of Bax and cleaved-casepase-3, and activated the NF-ĸB and PI3K/AKT/mTOR pathway in MPC5 cells exposed to high-glucose (HG). Real-time PCR results showed that HQH reduced the mRNA expression of TNF-α, IL-1ß, MCP-1, and IL-6. In conclusion, our results showed that HQH may attenuate podocyte injury by inhibiting MPC5 cell apoptosis induced by HG and NF-κB-mediated inflammation response through activation of the PI3K/AKT/mTOR pathway.

Identification of Plasma hsa_circ_0001230 and hsa_circ_0023879 as Potential Novel Biomarkers for Focal Segmental Glomerulosclerosis and circRNA-miRNA-mRNA Network Analysis.

INTRODUCTION: Focal segmental glomerulosclerosis (FSGS) is a common glomerulopathy with an unclear mechanism. The demand for FSGS clinical diagnostic biomarkers has not yet been met. Circular RNA (circRNA) is a novel non-coding RNA with multiple functions, but its diagnostic value for FSGS remains unexplored. This study aimed to identify circRNAs that could aid in early clinical diagnosis and to investigate their mechanisms in podocyte injury. METHODS: The signature of plasma circRNAs for FSGS was identified by circRNA microarray. The existence of circRNAs was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR), RNase R assay, and DNA sequencing. Plasma levels of circRNAs were evaluated by qRT-PCR. The diagnostic value was appraised by the receiver operating characteristic curve. The circRNA-miRNA-mRNA network was built with Cytoscape 7.3.2. Statistically significant differences were calculated by the Mann-Whitney U test. RESULTS: A total of 493 circRNAs (165 upregulated, 328 downregulated) were differentially expressed in the plasma of FSGS patients (n = 3) and normal controls (n = 3). Eight candidate circRNAs were demonstrated to be circular and stable transcripts. Among them, hsa_circ_0001230 and hsa_circ_0023879 were significantly upregulated in FSGS patients (n = 29) compared to normal controls (n = 51). The areas under the curve value of hsa_circ_0001230 and hsa_circ_0023879 were 0.668 and 0.753, respectively, while that of the two-circRNA panel was 0.763. The RNA pull-down analysis revealed that hsa_circ_0001230 and hsa_circ_0023879 could sponge hsa-miR-106a. Additionally, hsa_circ_0001230 and hsa_circ_0023879 positively regulated hsa-miR-106a target genes phosphatase and tensin homolog (PTEN) and Bcl-2-like protein 11 (BCL2L11) in podocytes. CONCLUSION: hsa_circ_0001230 and hsa_circ_0023879 are novel blood biomarkers for FSGS. They may regulate podocyte apoptosis by competitively binding to hsa-miR-106a.

Long noncoding RNA Glis2 regulates podocyte mitochondrial dysfunction and apoptosis in diabetic nephropathy via sponging miR-328-5p.

Podocyte apoptosis exerts a crucial role in the pathogenesis of DN. Recently, long noncoding RNAs (lncRNAs) have been gradually identified to be functional in a variety of different mechanisms associated with podocyte apoptosis. This study aimed to investigate whether lncRNA Glis2 could regulate podocyte apoptosis in DN and uncover the underlying mechanism. The apoptosis rate was detected by flow cytometry. Mitochondrial membrane potential (ΔΨM) was measured using JC-1 staining. Mitochondrial morphology was detected by MitoTracker Deep Red staining. Then, the histopathological and ultrastructure changes of renal tissues in diabetic mice were observed using periodic acid-Schiff (PAS) staining and transmission electron microscopy. We found that lncRNA Glis2 was significantly downregulated in high-glucose cultured podocytes and renal tissues of db/db mice. LncRNA Glis2 overexpression was found to alleviate podocyte mitochondrial dysfunction and apoptosis. The direct interaction between lncRNA Glis2 and miR-328-5p was confirmed by dual luciferase reporter assay. Furthermore, lncRNA Glis2 overexpression alleviated podocyte apoptosis in diabetic mice. Taken together, this study demonstrated that lncRNA Glis2, acting as a competing endogenous RNA (ceRNA) of miRNA-328-5p, regulated Sirt1-mediated mitochondrial dysfunction and podocyte apoptosis in DN.

Long noncoding RNA protein-disulfide isomerase-associated 3 regulated high glucose-induced podocyte apoptosis in diabetic nephropathy through targeting miR-139-3p.

BACKGROUND: Podocyte apoptosis plays a vital role in proteinuria pathogenesis in diabetic nephropathy (DN). The regulatory relationship between long noncoding RNAs (lncRNAs) and podocyte apoptosis has recently become another research hot spot in the DN field. AIM: To investigate whether lncRNA protein-disulfide isomerase-associated 3 (Pdia3) could regulate podocyte apoptosis through miR-139-3p and revealed the underlying mechanism. METHODS: Using normal glucose or high glucose (HG)-cultured podocytes, the cellular functions and exact mechanisms underlying the regulatory effects of lncRNA Pdia3 on podocyte apoptosis and endoplasmic reticulum stress (ERS) were explored. LncRNA Pdia3 and miR-139-3p expression were measured through quantitative real-time polymerase chain reaction. Relative cell viability was detected through the cell counting kit-8 colorimetric assay. The podocyte apoptosis rate in each group was measured through flow cytometry. The interaction between lncRNA Pdia3 and miR-139-3p was examined through the dual luciferase reporter assay. Finally, western blotting was performed to detect the effect of lncRNA Pdia3 on podocyte apoptosis and ERS via miR-139-3p. RESULTS: The expression of lncRNA Pdia3 was significantly downregulated in HG-cultured podocytes. Next, lncRNA Pdia3 was involved in HG-induced podocyte apoptosis. Furthermore, the dual luciferase reporter assay confirmed the direct interaction between lncRNA Pdia3 and miR-139-3p. LncRNA Pdia3 overexpression attenuated podocyte apoptosis and ERS through miR-139-3p in HG-cultured podocytes. CONCLUSION: Taken together, this study demonstrated that lncRNA Pdia3 overexpression could attenuate HG-induced podocyte apoptosis and ERS by acting as a competing endogenous RNA of miR-139-3p, which might provide a potential therapeutic target for DN.

Tangshen formula protects against podocyte apoptosis via enhancing the TFEB-mediated autophagy-lysosome pathway in diabetic nephropathy.

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease and currently there are no specific and effective drugs for its treatment. Podocyte injury is a detrimental feature and the major cause of albuminuria in DN. We previously reported Tangshen Formula (TSF), a Chinese herbal medicine, has shown therapeutic effects on DN. However, the underlying mechanisms remain obscure. AIM OF THE STUDY: This study aimed to explore the protective effect of TSF on podocyte apoptosis in DN and elucidate the potential mechanism. MATERIALS AND METHODS: The effects of TSF were assessed in a murine model using male KKAy diabetic mice, as well as in advanced glycation end products-stimulated primary mice podocytes. Transcription factor EB (TFEB) knockdown primary podocytes were employed for mechanistic studies. In vivo and in vitro studies were performed and results assessed using transmission electron microscopy, immunofluorescence staining, and western blotting. RESULTS: TSF treatment alleviated podocyte apoptosis and structural impairment, decreased albuminuria, and mitigated renal dysfunction in KKAy mice. Notably, TSF extracted twice showed a more significant reduction in proteinuria than TSF extracted three times. Accumulation of autophagic biomarkers p62 and LC3, and aberrant autophagic flux in podocytes of DN mice were significantly altered by TSF therapy. Consistent with the in vivo results, TSF prevented the apoptosis of primary podocytes exposed to AGEs and activated autophagy. However, the anti-apoptosis capacity of TSF was countered by the autophagy-lysosome inhibitor chloroquine. We found that TSF increased the nuclear translocation of TFEB in diabetic podocytes, and thus upregulated transcription of its several autophagic target genes. Pharmacological activation of TFEB by TSF accelerated the conversion of autophagosome to autolysosome and lysosomal biogenesis, further augmented autophagic flux. Conversely, TFEB knockdown negated the favorable effects of TSF on autophagy in AGEs-stimulated primary podocytes. CONCLUSIONS: These findings indicate TSF appears to attenuate podocyte apoptosis and promote autophagy in DN via the TFEB-mediated autophagy-lysosome system. Thus, TSF may be a therapeutic candidate for DN.

Influence of Didang Xianxiong Decoction on Apoptosis of Podocytes in Diabetes Rats Through PI3K/Akt Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo observe the protective effect of Didang Xianxiong decoction on the kidneys of diabetic rats， its regulation on the phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway， and its influence on podocyte apoptosis and explore the mechanism of Didang Xianxiong decoction in improving diabetic nephropathy. MethodThe diabetic model was established by a single intraperitoneal injection of streptozotocin （STZ） solution of 55 mg·kg-1. The successfully replicated model rats were randomly divided into the model group， Didang Xianxiong decoction group （8.10 g·kg-1）， Xiao Xianxiongtang group （4.05 g·kg-1）， Didangtang group （4.05 g·kg-1）， and alagebrium （ALT-711） group （3 mg·kg-1）， with six rats in each group. In addition， six rats were included in the blank group. After continuous administration for eight weeks， hematoxylin-eosin （HE） staining was used to observe the pathological changes in rats' kidney tissue. Masson staining was used to observe the degree of collagen deposition. Periodic acid-Schiff （PAS） staining was used to observe basement membrane lesions， and immunohistochemistry was used to detect the expression of phosphorylation （p）-PI3K and p-Akt proteins in rats' kidney tissue. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling （TUNEL） method was used to detect podocyte apoptosis. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） was used to detect the mRNA expression of PI3K and Akt in rats' kidney tissue. Western blot was used to detect the protein expression of PI3K， p-PI3K， Akt， p-Akt， B-cell lymphoma 2 （Bcl-2）， Bcl-2-associated X protein （Bax）， phosphorylation glycogen synthase kinase-3β （p-GSK-3β）， and Caspase-3 in the kidney tissue. ResultCompared with the normal group， the model group had compensatory expansion of glomeruli， proliferation of mesangial cells， a large amount of collagen deposition in the mesangial stroma， thickening of the basement membrane， decreased mRNA expression of PI3K and Akt， and inhibition of PI3K and Akt protein phosphorylation （P<0.01）. It also underwent enhanced apoptotic signaling， decreased expression of anti-apoptotic protein Bcl-2 （P<0.01）， and increased expression of Bax， p-GSK-3β， and Caspase-3 （P<0.01）. Compared with the model group， Didang Xianxiong decoction significantly improved kidney tissue pathology， increased mRNA expression of PI3K and Akt （P<0.01）， significantly up-regulated phosphorylation levels of PI3K and Akt proteins （P<0.01） and Bcl-2 expression （P<0.01）， downregulated the expression of Bax， p-GSK-3β， and Caspase-3 （P<0.01）， and weakened podocyte apoptotic signaling. ConclusionDidang Xianxiong decoction may promote the activation of the PI3K/Akt signaling pathway， inhibit podocyte apoptosis， and thus slow down the progression of diabetic nephropathy.

Effect of Xiaoyu Xiezhuo Drink on Podocyte Apoptosis and Expression of HIF1α in Diabetic Kidney Disease Mice / 浙江中医药大学学报

[Objective]To observe the effect of Xiaoyu Xiezhuo Drink on podocyte apoptosis and hypoxia inducible factor 1 alpha(HIF1α)expression in db/db diabetic kidney disease(DKD)model mice.[Methods]Six db/m mice were chosen as negative control group,eighteen db/db mice were chosen and divided into DKD model group,low dosage Xiaoyu Xiezhuo Drink group,high dosage Xiaoyu Xiezhuo Drink group,with six mice in each group.After gastric irrigation for twelve weeks,the urine was collected to test the levels of protein,β2-microglobulin(β2-MG),albumin/creatinine ratio(Acr),β2-microglobulin/creatinine ratio(β2-MG/Ucr);blood was collected to test the level of triglyceride(TG),total cholesterol(TC),albumin(Alb),blood urea nitrogen(BUN),serum creatinine(Scr);the kidney tissue was collected to observe the pathological change by light and electron microscope,and to test HIF1α,nephrin mRNA by Real-time polymerase chain reaction(RT-PCR).[Results]Compared with negative control group,the levels of urine protein,β2-MG,Acr,β2-MG/Ucr,serum TG,TC,BUN,Scr were increased(P＜0.01),serum Alb was decreased(P＜0.01);glomerular volume increased,capillary loops lobed,mesangial cells and matrix hyperplasia,interstitial inflammation and fibrosis increased,foot process fusion increased,basement membrane thickened;podocyte apoptosis was increased;expression of HIF1α mRNA was elevated(P＜0.01),and nephrin mRNA was descended in kidney tissue of DKD model group(P＜0.01).Compared with DKD model group,the level of urine protein,β2-MG,Acr,β2-MG/Ucr,serum TG,TC,BUN,Scr were decreased(P＜0.01),serum Alb was incresed(P＜0.01);the pathological changes of the kidney was improved;the apoptosis of podocyte was reduced;the expression of HIF1α mRNA was decreased(P＜0.01),and nephrin mRNA was incresed(P＜0.01)in the kidney tissue of varied dosage Xiaoyu Xiezhuo Drink groups.There was no statistical significance in the level of urine protein,β2-MG,Acr,β2-MG/Ucr,serum TG,TC,BUN,Scr,Alb,podocyte apoptosis,and HIF1α,nephrin mRNA in the kidney tissue between different dosage Xiaoyu Xiezhuo Drink groups(P＞0.05).[Conclusion]Xiaoyu Xiezhuo Drink could improve urinary protein,renal function,renal structure lesion and podocyte apoptosis in DKD mice,which perhaps by regulating the expression of HIF1α.

Danggui Buxuetang Inhibits Mitochondrial Fission and Apoptosis of Podocytes in Rat of Diabetic Kidney Disease via AKAP1/Drp1 Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo observe the effects of Danggui Buxuetang on the mitochondrial fission and apoptosis of podocytes in the rat model of diabetic kidney disease （DKD） and to explore the protective effect and mechanism of Danggui Buxuetang on DKD rats. MethodSD rats were randomized into a modeling group （n=65， fed with a high-sugar and high-fat diet） and a normal group （n=10， fed with a normal diet）. After 6 weeks， the modeled rats were injected intraperitoneally with streptozotocin （STZ） for the modeling of type 2 diabetes mellitus （T2DM）. Sixty T2DM rats were randomized into model， irbesartan （0.014 g·kg-1）， and low-， medium-， and high-dose （0.36， 0.72， 1.44 g·kg-1， respectively） Danggui Buxuetang groups and administrated with corresponding drugs by gavage for 16 weeks. The levels of fasting blood glucose （FBG） and 24 h urinary protein （24 h UTP） were determined at the end of the 16th week. The pathological changes of the renal tissue were observed by hematoxylin-eosin and Masson staining. The mitochondrial ultrastructure of rat podocytes was observed by transmission electron microscopy. The level of reactive oxygen species （ROS） in the renal tissue of rats was measured by the fluorescent probe labeling of dihydroethidium （DHE）. The apoptosis of renal cells was detected by terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL）. The expression levels of Synaptopodin， Podocin， and cleaved caspase-3 in renal podocytes were detected by the immunohistochemical method （IHC）. Western blot was employed to determine the protein levels of A-kinase anchoring protein 1 （AKAP1）， phosphorylated dynamin-related protein 1 （p-Drp1）， mitofusin-2 （Mfn2）， B-cell lymphoma-2 （Bcl-2）， and Bcl-2-associated X protein （Bax）. ResultCompared with the control group， the model group showed elevated levels of FBG and 24 h UTP， mesangial hyperplasia， basement membrane thickening， mitochondrial swelling， mitochondrial crista breakage and disorder， and increased ROS and TUNEL-positive cells. In addition， the model group showcased down-regulated expression of Synaptopodin and Podocin， increased expression of cleaved Caspase-3， up-regulated protein levels of AKAP1 and p-Drp1 ， and down-regulated protein levels of Mfn2 and Bcl-2/Bax （P<0.01）. Compared with the model group， high-dose Danggui Buxuetang lowered the levels of FBG and 24 h UTP， alleviated the pathological injuries of the renal tissue and the mitochondrial injury of podocytes， decreased ROS and TUNEL-positive cells， promoted the expression of Synaptopodin and Podocin， inhibited the expression of cleaved Caspase-3， down-regulated the protein levels of AKAP1 and p-Drp1， and up-regulated the protein levels of Mfn2 and Bcl-2/Bax （P<0.05， P<0.01）. ConclusionDanggui Buxuetang may inhibit mitochondrial fission and apoptosis of podocytes and reduce urine protein by regulating the AKAP1/Drp1 pathway， thereby delaying the progression of DKD.

Urinary exosomes from patients with diabetic kidney disease induced podocyte apoptosis via microRNA-145-5p/Srgap2 and the RhoA/ROCK pathway.

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease without early diagnostic and specific therapeutic approaches. Podocyte apoptosis and loss play important roles in the pathological process of DKD. This study aimed to explore whether urinary exosomes from type 2 diabetes patients with DKD could induce podocyte apoptosis and the underlying pathological mechanisms. The exosomes were isolated from the urine samples of patients with DKD (DKD-Exo). Later, they were taken up and internalized by MPC5 cells. MPC5 cells were co-cultured with DKD-Exo (45 µg/ml) for 24 h in the presence or absence of microRNA-145-5p (miR-145-5p) inhibitor, fasudil and pcDNA-Srgap2 transfection. MiR-145-5p and Srgap2 expression was evaluated using real-time quantitative PCR. The protein levels of Srgap2, Bcl-2, Bax, and cleaved caspase-3, as well as ROCK activity were determined using Western blotting. Cell apoptosis was measured using flow cytometry and the TUNEL assay. miR-145-5p expression in MPC5 cells exposed to DKD-Exo was markedly upregulated. miR-145-5p negatively regulated Srgap2 levels. Exposure of MPC5 cells to DKD-Exo reduced Srgap2 expression and activated ROCK, which was partly reversed by the presence of the miR-145-5p inhibitor or Srgap2 overexpression. The apoptosis of MPC5 cells exposed to DKD-Exo increased significantly, which was counteracted by the addition of the miR-145-5p inhibitor and fasudil. The results showed that urinary exosomal miR-145-5p from patients with DKD induced podocyte apoptosis by inhibiting Srgap2 and activating the RhoA/ROCK pathway, suggesting that urinary exosomal miR-145-5p is involved in the pathological process of DKD and could become a noninvasive diagnostic biomarker for DKD.

COL4A3 Mutation Induced Podocyte Apoptosis by Dysregulation of NADPH Oxidase 4 and MMP-2.

Introduction: Podocyte apoptosis is a common mechanism driving progression in Alport syndrome (AS). This study aimed to investigate the mechanism of podocyte apoptosis caused by COL4A3 mutations. Methods: We recruited patients with autosomal dominant AS (ADAS). Patients with minimal change disease (MCD) were recruited as controls. Microarray analysis was carried out on isolated glomeruli from the patients and validated. Then, corresponding mutant human podocytes (p.C1616Y) and 129 mice (p.C1615Y, the murine homolog to the human p.C1616Y) were constructed. The highest differentially expressed genes (DEGs) from microarray analysis were validated in transgenic mice and podocytes before and after administration of MMP-2 inhibitor (SB-3CT) and NOX4 inhibitor (GKT137831). We further validated NOX4/MMP-2/apoptosis pathway by real-time polymerase chain reaction (PCR), immunohistochemistry, and western blot in renal tissues from the ADAS patients. Results: Using microarray analysis, we observed that DEGs, including NOX4/H2O2, MMP-2, and podocyte apoptosis-related genes were significantly upregulated. These genes were validated by real-time PCR, histologic analysis, and western blot in corresponding mutant human podocyte (p.C1616Y) and/or mice models (p.C1615Y). Moreover, we found podocyte apoptosis was abrogated and MMP-2 expression was down-regulated both in vivo and in vitro by NOX4 inhibition, urinary albumin-to-creatinine ratio, 24-hour proteinuria; and renal pathologic lesion was attenuated by NOX4 inhibition in vivo. Furthermore, podocyte apoptosis was attenuated whereas NOX4 expression remained the same by inhibition of MMP-2 both in vivo and in vitro. Conclusion: These results indicated that NOX4 might induce podocyte apoptosis through the regulation of MMP-2 in patients with COL4A3 mutations. Our findings provided new insights into the mechanism of ADAS.

GLP-1 receptor agonist, liraglutide, protects podocytes from apoptosis in diabetic nephropathy by promoting white fat browning.

Glucagon like peptide-1 receptor agonists (GLP-1RAs) belong to the class of incretin drugs. Incretin is a hormone secreted into blood by intestinal cells after food stimulation that induces insulin secretion. Liraglutide is a long-acting GLP-1RA that can reduce blood pressure, blood lipids, and inflammation. Previous studies showed that liraglutide can promote white fat browning and improve renal outcomes in patients with type 2 diabetes mellitus. However, no studies have linked white fat browning to kidney damage. The objective of this study was to investigate the effects of liraglutide-induced white fat browning on podocyte apoptosis in diabetic nephropathy. We also aimed to determine whether podocytes express glucagon like peptide-1 receptor (GLP-1R) and if liraglutide directly affects podocytes via GLP-1R. We assessed fat and renal function in db/db and wild-type mice and the effects of adipocyte conditioned medium on cultured podocytes. Liraglutide (400 mg/kg/d) was subcutaneously injected for 8 weeks. Liraglutide promoted white fat browning in vivo. During adipogenic differentiation of 3T3-L1 cells in vitro, liraglutide also upregulated expression of peroxisome proliferator-activated receptor γ coactivator-1 alpha (PGC1α) and uncoupling protein 1 (UCP1), which can induce white fat browning in vitro. Furthermore, we found that supernatant from 3T3-L1 cells stimulated by liraglutide reduced podocyte apoptosis. The inhibitory effect of liraglutide on apoptosis was eliminated by exogenous TNF-α. Finally, podocytes express GLP-1R. In vivo and in vitro studies showed that the apoptosis of podocytes in diabetic nephropathy may be related to the effect of liraglutide on promoting white lipid browning. Similarly, liraglutide may directly affect podocytes via GLP-1R.

Astragaloside IV attenuates podocyte apoptosis through ameliorating mitochondrial dysfunction by up-regulated Nrf2-ARE/TFAM signaling in diabetic kidney disease.

Defective antioxidant system as well as mitochondrial dysfunction contributes to the pathogenesis and progression of diabetic kidney disease (DKD). Nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated signaling is the central defensive mechanism against oxidative stress and therefore pharmacological activation of Nrf2 is a promising therapeutic strategy. In this study, using molecular docking we found that Astragaloside IV (AS-IV), an active ingredient from traditional formula of Huangqi decoction (HQD), exerted a higher potential to promote Nrf2 escape from Keap1-Nrf2 interaction via competitively bind to amino acid sites in Keap1. When podocyte exposed to high glucose (HG) stimulation, mitochondrial morphological alterations and podocyte apoptosis were presented and accompanied by Nrf2 and mitochondrial transcription factor A (TFAM) downregulation. Mechanistically, HG promoted a decrease in mitochondria-specific electron transport chain (ETC) complexes, ATP synthesis and mtDNA content as well as increased ROS production. Conversely, all these mitochondrial defects were dramatically alleviated by AS-IV, but suppression of Nrf2 with inhibitor or siRNA and TFAM siRNA simultaneously alleviated the AS-IV efficacy. Moreover, experimental diabetic mice exhibited significant renal injury as well as mitochondrial disorder, corresponding with the decreased expression of Nrf2 and TFAM. On the contrary, AS-IV reversed the abnormality and the Nrf2 and TFAM expression were also restored. Taken together, the present findings demonstrate the improvement of AS-IV on mitochondrial function, thereby resistance to oxidative stress-induced diabetic kidney injury and podocyte apoptosis, and the process is closely associated with activation of Nrf2-ARE/TFAM signaling.

Podocyte-specific deletion of ubiquitin carboxyl-terminal hydrolase L1 causes podocyte injury by inducing endoplasmic reticulum stress.

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a unique component of the ubiquitin-proteasome system (UPS), which has multiple activities in maintaining intracellular ubiquitin levels. We previously reported the aberrant low expression of UCHL1 in podocytes of non-immune complex-mediated glomerulonephritis, and recent studies indicate that anti-UCHL1 antibody was responsible for the refractory minimal change disease (MCD), but the specific effect of UCHL1 to the podocytopathy has not been determined. Therefore, we generated podocyte-specific UCHL1 gene knockout (UCHL1cre/cre) rats model. Podocyte-specific UCHL1 knockout rats exhibited severe kidney damage, including segmental/global glomerulosclerosis, kidney function damage and severe proteinuria, compared with littermate control. Subsequently, by carrying out mass spectrometry analysis of isolated glomeruli of rats, abnormal protein accumulation of ECM-receptor Interaction was found in UCHL1cre/cre rats. Mechanistic studies in vivo and in vitro revealed that aberrant protein accumulation after UCHL1 deficiency induced endoplasmic reticulum (ER) stress, unfolded protein reaction (UPR) to reduce the protein level of podocyte skeleton proteins, and CHOP mediated apoptosis as well, which related to the dysfunction of the ubiquitin-proteasome system with decreased free monomeric ubiquitin level, thereby affecting protein ubiquitination and degradation. In addition, inhibition of ER stress by 4-PBA could attenuate the degree of ER stress and podocyte dysfunction. Our study indicates that UCHL1 is a potential target for preventing podocytes injury in some non-immune complex-mediated glomerulopathy.

Emodin Ameliorates High Glucose-Induced Podocyte Apoptosis via Regulating AMPK/mTOR-Mediated Autophagy Signaling Pathway.

OBJECTIVE: To investigate the effect of emodin on high glucose (HG)-induced podocyte apoptosis and whether the potential anti-apoptotic mechanism of emodin is related to induction of adenosine-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)-mediated autophagy in podocytes (MPC5 cells) in vitro. METHODS: MPC5 cells were treated with different concentrations of HG (2.5, 5, 10, 20, 40, 80 and 160 mmol/L), emodin (2, 4, 8 µ mol/L), or HG (40 mmol/L) and emodin (4 µ mol/L) with or without rapamycin (Rap, 100 nmol/L) and compound C (10 µ mol/L). The viability and apoptosis of MPC5 cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy marker light chain 3 (LC3) I/II, and AMPK/mTOR signaling pathway-related proteins were determined by Western blot. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy. RESULTS: HG at 20, 40, 80 and 160 mmol/L dose-dependently induced cell apoptosis in MPC5 cells, whereas emodin (4 µ mol/L) significantly ameliorated HG-induced cell apoptosis and caspase-3 cleavage (P<0.01). Emodin (4 µ mol/L) significantly increased LC3-II protein expression levels and induced RFP-LC3-containing punctate structures in MPC5 cells (P<0.01). Furthermore, the protective effects of emodin were mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 µ mol/L) reversed emodin-induced autophagy activation. CONCLUSION: Emodin ameliorated HG-induced apoptosis of MPC5 cells in vitro that involved induction of autophagy through the AMPK/mTOR signaling pathway, which might provide a potential therapeutic option for diabetic nephropathy.

Emodin Ameliorates High Glucose-Induced Podocyte Apoptosis via Regulating AMPK/mTOR-Mediated Autophagy Signaling Pathway / 中国结合医学杂志

OBJECTIVE@#To investigate the effect of emodin on high glucose (HG)-induced podocyte apoptosis and whether the potential anti-apoptotic mechanism of emodin is related to induction of adenosine-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)-mediated autophagy in podocytes (MPC5 cells) in vitro.@*METHODS@#MPC5 cells were treated with different concentrations of HG (2.5, 5, 10, 20, 40, 80 and 160 mmol/L), emodin (2, 4, 8 µ mol/L), or HG (40 mmol/L) and emodin (4 µ mol/L) with or without rapamycin (Rap, 100 nmol/L) and compound C (10 µ mol/L). The viability and apoptosis of MPC5 cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy marker light chain 3 (LC3) I/II, and AMPK/mTOR signaling pathway-related proteins were determined by Western blot. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy.@*RESULTS@#HG at 20, 40, 80 and 160 mmol/L dose-dependently induced cell apoptosis in MPC5 cells, whereas emodin (4 µ mol/L) significantly ameliorated HG-induced cell apoptosis and caspase-3 cleavage (P<0.01). Emodin (4 µ mol/L) significantly increased LC3-II protein expression levels and induced RFP-LC3-containing punctate structures in MPC5 cells (P<0.01). Furthermore, the protective effects of emodin were mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 µ mol/L) reversed emodin-induced autophagy activation.@*CONCLUSION@#Emodin ameliorated HG-induced apoptosis of MPC5 cells in vitro that involved induction of autophagy through the AMPK/mTOR signaling pathway, which might provide a potential therapeutic option for diabetic nephropathy.

Corrigendum: Sanqi Oral Solution Mitigates Proteinuria in Rat Passive Heymann Nephritis and Blocks Podocyte Apoptosis via Nrf2/HO-1 Pathway.

[This corrects the article DOI: 10.3389/fphar.2021.727874.].

miR-30a-5p promotes glomerular podocyte apoptosis via DNMT1-mediated hypermethylation under hyperhomocysteinemia.

Abnormal elevation of homocysteine (Hcy) level is closely related to the development and progression of chronic kidney disease (CKD), with the molecular mechanisms that are not fully elucidated. Given the demonstration that miR-30a-5p is specifically expressed in glomerular podocytes, in the present study we aimed to investigate the role and potential underlying mechanism of miR-30a-5p in glomerular podocyte apoptosis induced by Hcy. We found that elevated Hcy downregulates miR-30a-5p expression in the mice and Hcy-treated podocytes, and miR-30a-5p directly targets the 3'-untranslated region (3'-UTR) of the forkhead box A1 (FOXA1) and overexpression of miR-30a-5p inhibits FOXA1 expression. By nMS-PCR and MassARRAY quantitative methylation analysis, we showed the increased DNA methylation level of miR-30a-5p promoter both and . Meanwhile, dual-luciferase reporter assay showed that the region between --1400 and --921 bp of miR-30a-5p promoter is a possible regulatory element for its transcription. Mechanistic studies indicated that DNA methyltransferase enzyme 1 (DNMT1) is the key regulator of miR-30a-5p, which in turn enhances miR-30a-5p promoter methylation level and thereby inhibits its expression. Taken together, our results revealed that epigenetic modification of miR-30a-5p is involved in glomerular podocyte injury induced by Hcy, providing a diagnostic marker candidate and novel therapeutic target in CKD induced by Hcy.

Jiangzhi Tongluo Soft Capsules Regulate SIRT1/FoxO3 Pathway to Affect Cell Apoptosis in Rats with Membranous Nephropathy / 中国实验方剂学杂志

ObjectiveTo observe the effect of Jiangzhi Tongluo soft capsule on the protein levels of silent mating-type information regulation 2 homolog 1 （SIRT1） and forkhead transcription factor FoxO3 and podocyte apoptosis in the renal tissue of rats with membranous nephropathy and to reveal the underlying molecular mechanisms for the treatment of MN. MethodSixty male SD rats were randomly assigned into 6 groups with 10 rats each. The six groups included a normal group， a model group， benazepril hydrochloride group， and Jiangzhi Tongluo soft capsule groups of low， medium and high doses （25， 50， 100 mg·kg-1， respectively）. The model rats were established by injection with cationized bovine serum albumin into the tail vein. After modeling， the rats were administrated with corresponding agents by gavage for 4 weeks. At the end of the 4th week， an electron microscope was used to observe the pathological changes in the kidney. Western blot was employed to detect the protein levels of SIRT1 and FoxO3 protein in rat kidney， and immunohistochemistry to detect the expression of B lymphocytoma-2 （Bcl-2）， Bcl-2-associated X protein （Bax）， Bcl-2-associated death promoter （Bad）， and podocyte split diaphragm proteins nephrin and podocin. ResultCompared with normal group， the expression of pro-apoptotic factors Bax， Bad， and FoxO3 in the kidney was up-regulated （P<0.05）， while that of anti-apoptotic factors Bcl-2， SIRT1， nephrin， and podocin was down-regulated （P<0.05） after modeling. Compared with the model group， the treatments down-regulated the expression of Bax， Bad， and FoxO3 （P<0.05） and up-regulated that of Bcl-2， SIRT1， nephrin， and podocin （P<0.05）. ConclusionJiangzhi Tongluo soft capsule may regulate the SIRT1/FoxO3 pathway to reduce podocyte apoptosis and maintain podocyte structure stability， thereby exerting the renal protection effect.

Ginsenoside Rb1 alleviates diabetic kidney podocyte injury by inhibiting aldose reductase activity.

Panax notoginseng, a traditional Chinese medicine, exerts beneficial effect on diabetic kidney disease (DKD), but its mechanism is not well clarified. In this study we investigated the effects of ginsenoside Rb1 (Rb1), the main active ingredients of Panax notoginseng, in alleviating podocyte injury in diabetic nephropathy and the underlying mechanisms. In cultured mouse podocyte cells, Rb1 (10 µM) significantly inhibited high glucose-induced cell apoptosis and mitochondrial injury. Furthermore, Rb1 treatment reversed high glucose-induced increases in Cyto c, Caspase 9 and mitochondrial regulatory protein NOX4, but did not affect the upregulated expression of aldose reductase (AR). Molecular docking analysis revealed that Rb1 could combine with AR and inhibited its activity. We compared the effects of Rb1 with eparestat, a known aldose reductase inhibitor, in high glucose-treated podocytes, and found that both alleviated high glucose-induced cell apoptosis and mitochondrial damage, and Rb1 was more effective in inhibiting apoptosis. In AR-overexpressing podocytes, Rb1 (10 µM) inhibited AR-mediated ROS overproduction and protected against high glucose-induced mitochondrial injury. In streptozotocin-induced DKD mice, administration of Rb1 (40 mg·kg-1·d-1, ig, for 7 weeks) significantly mitigated diabetic-induced glomerular injuries, such as glomerular hypertrophy and mesangial matrix expansion, and reduced the expression of apoptotic proteins. Collectively, Rb1 combines with AR to alleviate high glucose-induced podocyte apoptosis and mitochondrial damage, and effectively mitigates the progression of diabetic kidney disease.

Sanqi Oral Solution Mitigates Proteinuria in Rat Passive Heymann Nephritis and Blocks Podocyte Apoptosis via Nrf2/HO-1 Pathway.

Idiopathic membranous nephropathy (IMN) is the most common pathological type in adult nephrotic syndrome where podocyte apoptosis was found to mediate the development of proteinuria. Sanqi oral solution (SQ), an effective Chinese herbal preparation clinically used in treatment of IMN for decades, plays an important role in reducing proteinuria, but the underlying mechanisms have not been fully elucidated yet. The current study tested the hypothesis that SQ directly lessens proteinuria in IMN by reducing podocyte apoptosis. To investigate the effects of SQ, we established the experimental passive Heymann nephritis (PHN) rat model induced by anti-Fx1A antiserum in vivo and doxorubicin hydrochloride (ADR)-injured apoptotic podocyte model in vitro. SQ intervention dramatically reduced the level of proteinuria, together with the rat anti-rabbit IgG antibodies, complement C3, and C5b-9 deposition in glomerulus of PHN rats, accompanied by an elevation of serum albumin. Protein expression of synaptopodin, marker of podocyte injury, restored after SQ administration, whereas the electron microscopic analysis indicated that fusion of foot processes, and the pachynsis of glomerular basement membrane was markedly diminished. Further studies showed that SQ treatment could significantly inhibit podocyte apoptosis in PHN rats and ADR-injured podocytes, and protein levels of Cleaved Caspase-3 or the ratio of Bax/Bcl-2 were significantly decreased with SQ treatment in vivo or in vitro. Moreover, we found that the nuclear factor erythroid 2-related factor-2/heme oxygenase 1 (Nrf2/HO-1) pathway mediated the anti-apoptosis effective of SQ in podocyte. Thus, SQ mitigates podocyte apoptosis and proteinuria in PHN rats via the Nrf2/HO-1 pathway.