OBJECTIVETo highlight current knowledge about M-type phospholipase A2 receptor (PLA2R) which is the first human autoantigen discovered in adult idiopathic membranous nephropathy.

DATA SOURCESRelevant articles published in English from 2000 to present were selected from PubMed. Searches were made using the terms "idiopathic membranous nephropathy, M-type PLA2R and podocyte."

STUDY SELECTIONArticles studying the role of M-type PLA2R in idiopathic membranous nephropathy were reviewed. Articles focusing on the discovery, detection and clinical observation of anti-PLA2R antibodies were selected.

RESULTSM-type PLA2R is a member of the mannose receptor family of proteins, locating on normal human glomeruli as a transmembrane receptor. The anti-PLA2R in serum samples from MN were primarily IgG4 subclass. Technologies applied to detect anti-PLA2R autoantibody are mainly WB, IIFT, ELISA and so on. Studies from domestic and overseas have identified a strongly relationship between circulating anti-PLA2R levels and disease activity.

CONCLUSIONRecent discoveries corresponding to PLA2R facilitate a better understanding on IMN pathogenesis and may provide a new tool to its diagnosis, differential diagnosis, risk evaluation, response monitoring and patient-specific treatment.

Animals ; Autoantigens ; metabolism ; Glomerulonephritis, Membranous ; immunology ; metabolism ; Humans ; Podocytes ; metabolism ; Receptors, Phospholipase A2 ; metabolism

OBJECTIVES: High fat-induced podocyte injury is one of the important factors leading to obesity related nephropathy (ORG), but the mechanism is not clear. This study aims to explore the mechanism of period circadian clock 3 (PER3) in the oxidative stress and inflammation induced by palmitic acid (PA) in podocytes. METHODS: The C57BL/6J mice were fed with chow and high-fat diet for 16 weeks. The PER3 expression in kidney tissues were detected in the normal body weight group and the obesity group. The PER3 mRNA and protein expression were detected after the podocytes were induced with different concentrations (0, 50, 150 and 300 μmol/L) of PA for 48 h. The PER3 mRNA and protein expression were detected after the podocytes were induced with 150 μmol/L PA for 0, 24, 36, and 48 h. Triglyceride (TG) levels were examined in the PA group, the adenovirus (ad)-PER3+PA group, and the siRNA-PER+PA group after the podocytes were transfected by Ad-PER3 or small interfering RNA (siRNA)-PER3 for 48 h and subsequently were induced with 150 μmol/L PA for 48 h. The differential gene expression was detected using RNA sequencing (RNA-seq) after podocytes were transfected by siRNA-PER3 (siRNA-PER3 group) and siRNA-control (siRNA-control group), respectively. The mRNA levels of nephrin, podocin, podocalyxin, podoplanin, superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), catalase (CAT), and the levels of malondialdehyde (MDA), glutathione (GSH), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β) and interleukin-2 (IL-2) were detected after podocytes were transfected with Ad-PER3 or Ad-control for 48 h and then they were induced by 150 μmol/L PA for 48 h. RESULTS: The PER3 was down-regulated in the obesity group compared with the normal body weight group ( CONCLUSIONS PER3 can decrease the PA-induced oxidative stress and inflammatory factor secretion via inhibiting the lipogenesis in podocytes.
Animals ; Circadian Clocks ; Mice ; Mice, Inbred C57BL ; Oxidative Stress ; Palmitic Acid/toxicity* ; Podocytes/metabolism*

The TRPC family consists of multiple important cationic channels in mammals that participate in a variety of physiological and pathological processes. Our previous studies have shown that transforming growth factor-β1 (TGF-β1) increases the expression of TRPC6 in podocytes, but the roles of other members of the TRPC family in podocytes require further investigation. In this study, we investigated the effect of TGF-β1 on the expression of the TRPC family and the role of the TRPC family in the changes of the intracellular Ca²⁺ concentration ([Ca²⁺]_i) in podocytes induced by TGF-β1. The model of podocyte injury was established by treatment with TGF-β1 in immortalized glomerular podocytes (MPC5) in vitro. qRT-PCR and Western blot were used to detect the effect of TGF-β1 on the mRNA and protein expression of each TRPC family member. After the expression of each TRPC family member was knocked down by a siRNA-based approach and blocked by SKF96365, respectively, free cytosolic Ca²⁺ was measured using the fluorescent Ca²⁺ indicator Fluo-3/AM, and the dynamic change of [Ca²⁺]_i in podocytes was detected by a dynamic high-speed calcium imaging system. The results showed that TGF-β1 increased the protein expression of TRPC1/3/6 in podocytes, but had no effects on the protein expression of TRPC4. The protein expression levels of TRPC5/7 were only affected by 4 ng/mL and 8 ng/mL TGF-β1, respectively. TGF-β1 increased TRPC1/3/6 mRNA levels in podocytes, however had no effects on TRPC4/5/7 mRNA. TGF-β1 significantly increased [Ca²⁺]_i in podocytes. Knockdown of TRPC1/4/5/7 in podocytes had no significant effect on the [Ca²⁺]_i induced by TGF-β1, but TRPC3/6 knockdown significantly decreased the [Ca²⁺]_i. There was no significant difference in the [Ca²⁺]_i between the TRPC6 siRNA-treated group and SKF96365-treated group, but the [Ca²⁺]_i of the TRPC3 siRNA-treated group was significantly higher than that of SKF96365-treated group. These results demonstrate that TGF-β1 increases the expression of the TRPC1/3/6 in podocytes. TGF-β1 increases [Ca²⁺]_i in podocytes, which is dependent on the TRPC3/6 expression. Our results also suggest that the effect of TRPC6 on [Ca²⁺]_i in podocytes may be greater than that of TRPC3.
Animals ; TRPC6 Cation Channel/metabolism* ; Calcium/metabolism* ; TRPC Cation Channels/metabolism* ; Podocytes/metabolism* ; Transforming Growth Factor beta1/metabolism* ; RNA, Small Interfering/metabolism* ; RNA, Messenger/metabolism* ; Mammals/metabolism*

Animals ; Apoptosis ; Diabetic Nephropathies ; metabolism ; pathology ; Glucose ; metabolism ; Membrane Potential, Mitochondrial ; Mice ; Mice, Transgenic ; Mitochondria ; pathology ; Podocytes ; cytology

OBJECTIVETo explore the podocyte injury in patients with diabetic nephropathy (DN) and analyze its relationship with glucose regulated protein 78 (GRP78) and proteinuria.

METHODSThe clinical data of 48 patients diagnosed as DN by renal biopsy were reviewed. All patients were divided into two groups according to proteinuria (>3.5 g/d, n=31 and 3.5 g/d, n=17). The density of podocytes was illustrated by immunohistochemistry staining of Wilms tumor-1 (WT-1), and the immunofluorescence double-staining results of synaptopodin and GRP78 in podocytes were detected.

RESULTSThe podocyte dentistry of urine protein > 3.5 g/d group was significantly lower than that of urine protein>3.5 g/d group urine protein<3.5 g/d group(P=0.003), and it was negatively correlated with proteinuria (P=0.005). The expressions of synaptopodin and GRP78 in podocytes were also negatively correlated with proteinuria (P=0.004 and P=0.001).

CONCLUSIONThe podocyte injury is aggravated with increased proteinuria in DN patients, along with the decrease of the adaptive ability of endoplasmic reticulum to stress.

Adult ; Diabetic Nephropathies ; complications ; metabolism ; pathology ; Female ; Heat-Shock Proteins ; metabolism ; Humans ; Male ; Middle Aged ; Podocytes ; pathology ; Proteinuria ; etiology

OBJECTIVEDifferent from primary membranous nephropathy, hepatitis B virus associated membranous nephropathy (HBV-MN) shows lower deposits of membrane attack complex (C5b-9) in glomerular subepithelium. The causes of relatively low complement activation in this disease remain unclear. The aim of this study was to investigate the influence of hepatitis B x protein (HBx) on the expression of CD59 and Crry in mouse podocytes.

METHODCultured mouse podocytes were divided into adenovirus vector hepatitis B virus X gene (Ad-HBx) transfected group (Ad-X group), blank podocytes group (B group) and adenovirus vector transfected group (Ad group). CD59 and Crry mRNA expression were assayed by semiquantitative RT-PCR. CD59 and Crry expression were tested by flow cytometry. The effect of HBx on complement activation was evaluated with MTT method. And then, the effects of P38MAPK, PI-3K and ERK1/2 pathway inhibitors (SB203580, LY294002, U0126) and DMSO on CD59 and Crry expression were respectively detected by flow cytometry.

RESULTProteins CD59 and Crry expression rates (%) in group B, Ad group and Ad-X group were 17.71 ± 3.81, 18.29 ± 3.36 and 45.7 ± 9.01; 18 ± 2.31, 21.78 ± 2.01 and 47.45 ± 9.95, respectively. Compared with group B, CD59 and Crry expression in group Ad was not significantly different (P values for both > 0.05), but CD59 and Crry protein expression in Ad-X group was significantly higher than that in groups B and Ad (P values for both < 0.005); CD59 and Crry gene expression in group Ad was not significantly different from that in group B (P values for both > 0.05). However, CD59 and Crry gene expression of Ad-X group was significantly higher than that in groups B and Ad (P values for both < 0.05). Flow cytometry detected CD59 protein expression rates (%) were 17.35 ± 1.24, 46.19 ± 9.77, 43.03 ± 6.83 and 40.04 ± 6.39 and Crry protein expression rates (%) were 18.14 ± 3.56, 31.95 ± 1.68, 31.95 ± 1.69 and 37.14 ± 3.92 after SB203580, LY294002, U0126 and DMSO were added to Ad-X group respectively. P38 pathway inhibition resulted in significantly lower CD59 and Crry expression than Ad-X group (P values for all < 0.005), but PI-3K, ERK1/2 pathway inhibitors and DMSO had no significant effect on the expression of CD59 and Crry (P values for all > 0.05). The inhibition rates of cell lysis were significantly higher in Ad-X group than in groups B and Ad at each serum dilution point (P values for all < 0.05), while groups B and Ad had no significant difference in cell viability.

CONCLUSIONHBx can up-regulate CD59 and Crry expression in podocytes through activating P38 pathway, resulting in decreased complement activation, which may facilitate latent HBV infection in podocytes and play a role in development of hepatitis B virus associated glomerulonephritis (HBV-GN).

Animals ; CD59 Antigens ; metabolism ; Cells, Cultured ; Mice ; Podocytes ; immunology ; metabolism ; Receptors, Complement ; metabolism ; Trans-Activators ; metabolism ; p38 Mitogen-Activated Protein Kinases ; metabolism

OBJECTIVETo investigate the regulation of calcineurin (CaN) by endoplasmic reticulum stress (ERS) in podocytes in vitro and in vivo at the stage microalbuminuria in diabetic nehropathy (DN).

METHODSThe urinary albumin excretions of C57BLKS/J (Lepr) db/db and db/m mice at the ages of 6, 9, and 12 weeks were measured. The expressions of CaN and synaptopodin of these mice were observed. In immortalized mouse podocytes, the expression of podocyte CaN incubated with different concentrations of paltimate was quantitatively determined by real-time PCR. The changes of CaN incubated with paltimate with or without ursodeoxy-cholic acid (UDCA) were analyzed by confocal microscopy and Western blotting.

RESULTSAs urine protein increased, the expression of CaN was enhanced and the expression of synaptopodin was reduced in early stage DN db/db mice potocytes. In immortalized mouse podocytes, as the concentrations of palmitate increased, CaN mRNA increased. By confocal microscopy, the fluorescence intensity of CaN increased in palmitate treatment group. After co-incubation with palmitate and UDCA, the fluorescence intensity decreased. The similar results were shown by Western blotting.

CONCLUSIONAt the stage of microalbuminuria in DN, ERS in podocytes up-regulates the expression of CaN.

Animals ; Calcineurin ; metabolism ; Cells, Cultured ; Diabetes Mellitus, Experimental ; metabolism ; Diabetic Nephropathies ; metabolism ; Endoplasmic Reticulum Stress ; Male ; Mice ; Mice, Inbred C57BL ; Microfilament Proteins ; metabolism ; Podocytes ; metabolism

OBJECTIVE: To investigate the effect of podocyte ultrastructure and changes of nephrin and the podocin expression on the pathogenesis of diabetic nephropathy (DN) in rats. METHODS: Twenty Wistar rats were divided into 2 groups: a normal control group and a DN model group.We determined the 24h proteinuria and other biochemical indexes, measured the ultrastructures of podocytes with electronic microscope, and detected the expression of nephrin and podocin with immunohistochemical technique and RT-PCR at the 4th and 8th weeks. RESULTS: The 24h proteinuria increased in the DN group; the number of podocytes was significantly lower; and the foot process width (FPW) obviously increased in the DN group compared with the normal group (P<0.01). The protein and mRNA expressions of nephrin and podocin reduced in the DN group.There was a negative correlation between the proteinuria and the protein expression of nephrin and podocin (P<0.01). CONCLUSION The reduction in glomerular podocyte number,the increased FPW, and the down-regulated expression of nephrin and podocin appear at the early stage of DN and become more serious with the disease progression.The podocyte lesion not only is associated with the degree of proteinuria,but also correlates with the development of glomerulosclerosis and damage of renal function.
Animals ; Diabetic Nephropathies ; metabolism ; pathology ; Intracellular Signaling Peptides and Proteins ; metabolism ; Male ; Membrane Proteins ; metabolism ; Podocytes ; metabolism ; pathology ; ultrastructure ; Proteinuria ; pathology ; Rats ; Rats, Wistar

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/pharmacology* ; AMP-Activated Protein Kinases/metabolism* ; Podocytes ; Caspase 3/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; Signal Transduction ; Apoptosis ; Sirolimus/pharmacology* ; Glucose/metabolism* ; Autophagy

OBJECTIVETo observe the effect of 11R-VIVIT on lipopolysaccharide (LPS)-induced expression of urokinase-type plasminogen activator receptor (uPAR) in podocytes.

METHODSA LPS-induced proteinuria mouse model and in vitro cultured podocytes treated with LPS were both divided into control group, LPS group and LPS+11 R-VIVIT group. The mRNA and protein expressions of uPAR in mouse kidney tissues and the podocytes were measured by real-time qPCR, laser scanning confocal microscopy and Western blotting.

RESULTSCompared with LPS group, LPS+11 R-VIVIT group showed a significantly lowered urine albumin/creatinine ratio (P<0.001) and markedly reduced mRNA and protein expressions of uPAR (PuPAR mRNA<0.001; PuPAR=0.001).

CONCLUSION11R-VIVIT can ameliorate proteinuria probably by decreasing the expression of uPAR in podocytes.

Animals ; Disease Models, Animal ; Lipopolysaccharides ; adverse effects ; Male ; Mice ; Mice, Inbred C57BL ; Oligopeptides ; pharmacology ; Podocytes ; drug effects ; metabolism ; Proteinuria ; drug therapy ; metabolism ; Receptors, Urokinase Plasminogen Activator ; metabolism