All-trans retinoic acid (ATRA) is a vitamin A derivative and plays an important role in the regulation of cell aggregation, differentiation, apoptosis, proliferation, and inflammatory response. In recent years, some progress has been made in the role of ATRA in renal diseases, especially its protective effect on podocytes. This article reviews the research advances in podocyte injury, characteristics of ATRA, podocyte differentiation and regeneration induced by ATRA, and the protective effect of ATRA against proliferation, deposition of fibers, and apoptosis.
Apoptosis ; drug effects ; Cell Differentiation ; drug effects ; Cell Proliferation ; drug effects ; Cytoprotection ; Humans ; Podocytes ; drug effects ; physiology ; Tretinoin ; pharmacology

Animals ; Epithelial Cells ; cytology ; drug effects ; Humans ; Kidney Tubules ; cytology ; drug effects ; Oleanolic Acid ; analogs & derivatives ; pharmacology ; Podocytes ; drug effects

As a major active component extracted from traditional Chinese herb Tripterygium wilfordii Hook F, triptolide exhibits multiple pharmacological effects. Autophagy is an evolutionary conserved intracellular catabolic process involved in cytoplasmic materials degradation. Autophagic dysfunction contributes to the pathologies of many human diseases, which makes it a promising therapeutic target. Recent studies have shown that triptolide exerts neuroprotection, anti-tumor activities, organ toxicity, and podocyte protection by modulating autophagy. This article highlights the current information on triptolide-modulated autophagy, analyzes the possible pathways involved, and describes the crosstalk between autophagy and apoptosis modulated by triptolide, in hope of providing implications for the roles of autophagy in pharmacological effects of triptolide and expanding its novel usage as an autophagy modulator.
Animals ; Apoptosis ; drug effects ; Autophagy ; drug effects ; Diterpenes ; pharmacology ; Epoxy Compounds ; pharmacology ; Humans ; Neoplasms ; drug therapy ; pathology ; Neuroprotective Agents ; pharmacology ; Phenanthrenes ; pharmacology ; Podocytes ; drug effects

OBJECTIVETo explore the effect of resveratrol on transforming growth factor-beta1 (TGF-beta1) induced transdifferentiation of podocytes.

METHODSMouse podocytes in vitro cultured under differentiating conditions for 10 days were divided into the normal group, the model group, the high dose resveratrol group, and the low dose resveratrol group. The podocytes in the high and low dose resveratrol groups were intervened with 5 micromol/L and 2 micromol/L resveratrol respectively for 30 min. Those in the model group and the two resveratrol treated groups were continually incubated with 5 ng/mL TGF-beta1 for 72 h. Those in the normal group were routinely cultured. The protein expression of podocyte phenotypic protein molecules such as E-cadherin, P-cadherin, zonula occludens-1 (ZO-1), NEPH1, and alpha-smooth muscle-actin (alpha-SMA) were detected by immunocytochemistry, flow cytometry (FCM), and Western blot. A simple albumin influx assay was used to evaluate the filtration barrier function of podocyte monolayer.

RESULTSCompared with the normal control group, E-cadherin (+) percentage rate, the protein expression of P-cadherin, ZO-1, and NEPH1 significantly decreased in the model group (P < 0.05), but the expression of alpha-SMA and albumin permeability across podocyte monolayers increased significantly (P < 0.05). Compared with the model group, E-cadherin (+) percentage rate significantly increased (P < 0.05) and albumin permeability across podocyte monolayers decreased significantly (P < 0.05) in the high and low dose resveratrol groups. In the low dose resveratrol group, the expression of P-cadherin and NEPH1 significantly increased (P < 0.05). In the high dose resveratrol group, the expression of P-cadherin, ZO-1, and NEPH1 increased significantly, and the expression of alpha-SMA decreased significantly (P < 0.05). The correlations between resveratrol concentrations and the expression of E-cadherin (+), P-cadherin, and NEPH1 were significantly positive (r(E-cadherin (+)) = 0.772, r(P-cadherin) = 0.756, r(NEPH1) = 0.809, P < 0.05).

CONCLUSIONThe role of resveratrol in inhibiting TGF-beta1 induced phenotype abnormality might be an important mechanism for preserving the integrality of glomerular filtration barrier and decreasing proteinuria.

Animals ; Cell Transdifferentiation ; drug effects ; Cells, Cultured ; Kidney Tubules ; cytology ; drug effects ; Mice ; Podocytes ; cytology ; drug effects ; Stilbenes ; pharmacology ; Transforming Growth Factor beta1 ; metabolism

OBJECTIVETo investigate the effects of Cordyceps Sinensis (CS) and Tripterygium wilfordii Polyglycosidium (TWP) on the podocytes in rats with diabetes nephropathy (DN).

METHODSRat models of DN were established and rats were randomly divided into the normal control group (Group A), the DN group (Group B), the CS group (Group C), the TWP group (Group D), and the CS combined TWP group (Group E). The changes of 24-h urinary protein count (24-h pro), blood glucose (Glu), blood urea nitrogen (BUN), serum creatinine (SCr), white blood cell (WBC), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and kidney weight/body weight (KW/BW) were determined 12 weeks later. The renal pathological changes were evaluated by HE staining. The microstructural changes of podocytes were observed by transmission electron microscope. The expressions of nephrin and podocin were detected by immunofluorescence staining.

RESULTSCompared with Group A, the levels of SCr and BUN were higher (P < 0.05), Glu, KW/BW, and 24 h pro were obviously higher in Group B (P < 0.01). There were less glomerular disorder, chronic tubulointerstitial damage and glomerular podocyte lesion in Group B. The expressions of the massive cortical nephrin and podocin protein were obviously less in Group B. Compared with Group B, the KW/BW and 24 h pro in Group C, D, and E were lower (P < 0.01). The pathomorphological improvement was exhibited in the glomerulus, tubules, and podocytes. The protein expressions of nephrin and podocin were higher in the renal cortex. Compared with Group C, the KW/BW and 24-h pro decreased in Group D and E, the expressions of nephrin and podocin were enhanced, and the lesions of the glomerulus, tubules, and podocytes were alleviated, showing statistical difference (P < 0.01). The most significant changes happened in Group E.

CONCLUSIONSCS and TWP could alleviate the DN proteinuria, protect and repair podocytes of DN rats. Its mechanisms might be correlated with up-regulating the expressions of nephrin and podocin. The combined use of CS and TWP could increase the efficacy and attenuate adverse reactions of TWP.

Animals ; Cordyceps ; Diabetes Mellitus, Experimental ; Diabetic Nephropathies ; pathology ; Male ; Podocytes ; drug effects ; Rats ; Rats, Sprague-Dawley ; Tripterygium

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

BACKGROUNDPodocyte apoptosis is recently indicated as an early phenomenon of diabetic nephropathy. Pancreatic β-cells exposed to saturated free fatty acid palmitate undergo irreversible endoplasmic reticulum (ER) stress and consequent apoptosis, contributing to the onset of diabetes. We hypothesized that palmitate could induce podocyte apoptosis via ER stress, which initiates or aggravates proteinuria in diabetic nephropathy.

METHODSPodocyte apoptosis was detected by 4',6-diamidio-2-phenylindole (DAPI) stained apoptotic cell count and Annexin V-PI stain. The expressions of ER molecule chaperone glucose-regulated protein 78 (GRP78), indicators of ER-associated apoptosis C/EBP homologous protein (CHOP), and Bcl-2 were assayed by Western blotting and real-time PCR. GRP78 and synaptopodin were co-localized by immunofluorescence stain.

RESULTSPalmitate significantly increased the percentage of cultured apoptotic murine podocytes time-dependently when loading 0.75 mmol/L (10 hours, 13 hours, and 15 hours compared with 0 hour, P < 0.001) and dose-dependently when loading palmitate ranging from 0.25 to 1.00 mmol/L for 15 hours (compared to control, P < 0.001). Palmitate time-dependently and dose-dependently increased the protein expression of GRP78 and CHOP, and decreased that of Bcl-2. Palmitate loading ranging from 0.5 to 1.0 mmol/L for 12 hours significantly increased mRNA of GRP78 and CHOP, and decreased that of Bcl-2 compared to control (P < 0.001), with the maximum concentration being 0.75 mmol/L. Palmitate 0.5 mmol/L loading for 3 hours, 8 hours, and 12 hours significantly increased mRNA of GRP78 and CHOP, and decreased that of Bcl-2 compared to 0 hour (P < 0.001), with the maximum effect at 3 hours. Confocal microscopy demonstrated that GRP78 expression was significantly increased when exposed to 0.5 mmol/L of palmitate for 8 hours compared to control.

CONCLUSIONPalmitate could induce podocyte apoptosis via ER stress, suggesting podocyte apoptosis and consequent proteinuria caused by lipotoxic free fatty acid could be ameliorated by relief of ER stress.

Apoptosis ; drug effects ; Cells, Cultured ; Endoplasmic Reticulum Stress ; physiology ; Heat-Shock Proteins ; analysis ; physiology ; Humans ; Insulin Resistance ; Palmitic Acid ; pharmacology ; Podocytes ; drug effects ; pathology

OBJECTIVETo study the effects of modified danggui buxue decoction (MDBD) on podocytes in adriamycin-induced nephropathy (DN) model rats.

METHODSSD rats were divided into four groups, i.e., the normal control group, the model group, the benazepril group, and the MDBD group. On the 7th, 28th, 42nd, and 56th day of modeling, the urine sample was collected to examine the dynamic changes of urinary albumin quantitation. The renal tissue was processed for the examinations under light microscope and electron microscope. The immunofluorescence of nephrin and podocin were detected. The expressions of the slit membrane expression protein in the renal tissue were further analyzed using RT-PCR and Western blot.

RESULTS(1) Urinary protein (UP): The UP did not obviously decrease in each treatment group on the 7th day, but it decreased so markedly on the 28th, 42nd, and 56th day. There was statistical difference in UP of the benazepril group and the MDBD group when compared with that of the model group (P < 0.05). The decrease was most obvious in the MDBD group. (2) Effects on the podocytes and the renal tissue:

RESULTSunder light microscope and electron microscope showed, when compared with the model group, the proliferation of mesangial cells, the renal tubule-interstitial lesion, the podocyte fusion, and the expressions of nephrin and podocin were milder, and the urinary albumin quantitation was more obviously reduced in the benazepril group and the MDBD group. But the renal fibrosis correlated renal pathological progress also existed, indicating the renal lesion degree was milder but could not be reversed. (3) Results of RT-PCR and Western blot: Statistical difference existed in the expressions of nephrin and podocin between the benazepril group and the MDBD group on the 56th day, when compared with the model group (P < 0.05).

CONCLUSIONMDBD showed therapeutic effects on adriamycin-induced nephropathy model rats. Its actions could be achieved through reducing albuminuria, inhibiting the proliferation of mesangial cells, attenuating the renal tubule-interstitial lesion, and protecting the integrity of the slit membrane structure.

Animals ; Doxorubicin ; adverse effects ; Drugs, Chinese Herbal ; pharmacology ; Kidney Diseases ; chemically induced ; pathology ; Male ; Podocytes ; drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo observe the effect of amiloride on the proteinuria of the 5/6 nephrectomy rats.

METHODSTo establish the 5/6 nephrectomy rats model and divide the experiment into 3 groups, sham operated group(Sham), 5/6 nephrectomy model group(NTX) and 5/6 nephrectomy with amiloride-treated group (NTX+amiloride, n=15). The concentration of protein and mRNA of uPAR and the change of podocytes motility were detected by coomassiebluestaining, immunofluorence method and real-time PCR.

RESULTSAt second week, compared with Control group, the 24 h urine protein of NTX group was significantly increased (47.50 ± 28.05 mg vs 14.28 ± 3.8 mg, P = 0.023). There was no statistical significance in 24-hour urine protein between NTX+amiloride group and NTX group (51.56 ± 21.03 mg vs 47.50 ± 28.05 mg, P = 0.748). The same situation was also observed at the time point of 12 week, comparing with NTX group, 24-hour urine protein decreased in Sham group (188.31 ± 29.82 mg vs 21.32 ± 8.59 mg, P = 0.000) and NTX+amiloride group (188.31 ± 29.82 mg vs 121.37 ± 31.14 mg, P=0.000), with statistical significance when comparing with Sham group, the expression of uPAR mRNA in NTX group was significantly increased (9.74 ± 1.44 vs 1.01 ± 0.13, P = 0.000). In contrast, the expression of uPAR mRNA in NTX rats treated with amiloride was significantly lower than in NTX group (9.74 ± 1.44 vs 5.01 ± 1.36, P = 0.000).

CONCLUSIONAmiloride can reduce the proteinuria of the 5/6 nephrectomy rats model of transient proteinuria by inhibiting the induction of uPAR expression.

Amiloride ; pharmacology ; Animals ; Cell Movement ; Disease Models, Animal ; Nephrectomy ; Podocytes ; drug effects ; metabolism ; Proteinuria ; drug therapy ; Rats ; Real-Time Polymerase Chain Reaction ; Receptors, Urokinase Plasminogen Activator ; metabolism

This study was aimed to construct eukaryotic expression vectors carrying the small hairpin RNA (shRNA) targeting TRPC6 gene and investigate the effect of TRPC6 knockdown on puromucin aminonucleoside (PAN)-induced podocyte injury. Two DNA sequences containing the small hairpin structure targeting TRPC6 were designed, synthesized and then inserted into the green fluorescence protein (GFP)-contained plasmids (pGC) to establish the plasmids pGCsi-TRPC6A and pGCsi-TRPC6B. Plasmids expressing scrambled shRNA were used as negative control and named pGCsi-NC. These plasmids were transfected into a conditionally immortalized murine podocyte cell line by using liposome. Flow cytometry was used to examine the transfection efficiency. TRPC6 mRNA and protein expression levels were detected by RT-PCR and Western blotting. Cultured podocytes were divided into four groups: control group, PAN treatment group, PAN+TRPC6 shRNA transfected group and PAN+scrambled shRNA transfected group. The paracelluar permeability to BSA was evaluated by Millicell-PCF Inserts and cell viability was measured by the trypan blue assay. Immunofluorescent assay was used to observe the distribution of α-actinin-4 and α-tubulin. The results showed that the transfection efficiency of the shRNA expression vector was about 45%. Expression levels of TRPC6 mRNA and protein were downregulated after transfection with pGCsi-TRPC6A and pGCsi-TRPC6B. Knocking down TRPC6 gene could effectively reverse the PAN-induced increase in the paracelluar permeability to BSA. The distribution of α-actinin-4 and α-tubulin was disrupted after treatment with PAN, which was reversed by knocking down TRPC6 gene. It was concluded that knocking down TRPC6 gene could effectively prevent podocytes from the permeability increase induced by PAN, which may be related to the regulation of podocyte cytoskeleton.
Animals ; Cell Membrane Permeability ; drug effects ; physiology ; Cell Survival ; drug effects ; physiology ; Cells, Cultured ; Gene Knockdown Techniques ; Mice ; Mice, Knockout ; Podocytes ; drug effects ; physiology ; Puromycin Aminonucleoside ; pharmacology ; TRPC Cation Channels ; genetics ; metabolism