• Childhood Kidney Diseases
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• v.22 no.1
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• pp.22-27
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• 2018

Purpose: Podocytes are important architectures that maintain the crucial roles of glomerular filtration barrier functions. Despite this structural importance, however, the mechanisms of the changes in podocytes that can be an important pathogenesis of minimal change nephrotic syndrome (MCNS) are not clear yet. The aim of this study was to investigate whether apoptosis is induced by interleukin (IL)-13 in cultured human podocytes. Methods: Human podocytes were treated with different IL-13 doses and apoptotic cells were analyzed using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL assay) and fluorescence-activated cell sorting (FACS). Results: The IL-13 increased the number of TUNEL-positive cells in a dose-dependent manner at 6 and 18 hours (P<0.05 and P<0.05, respectively). The apoptosis rate was appeared to be increased slightly in the IL-13-stimulated podocytes (8.63%, 13.02%, and 14.46%; 3, 10 and 30 ng/mL, respectively) than in the control cells (7.66%) at 12 hours by FACS assay. Conclusion: Our study revealed that IL-13 expression may increase podocyte apoptosis. Blocking the IL-13 signal pathway can potentially play an important role in regulating the apoptosis of podocytes.

• Childhood Kidney Diseases
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• v.23 no.1
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• pp.1-6
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• 2019

Nephrotic syndrome (NS) is the most common glomerular disorder in childhood, and a vast majority of cases are idiopathic. The precise cause of this common childhood disease is not fully elucidated despite significant advancements in our understanding of podocyte biology. Idiopathic NS has been considered "a disorder of T-cell function" mediated by a circulating factor that alters podocyte function resulting in massive proteinuria since the last four decades. Several circulatory factors released from T-cells are considered to be involved in pathophysiology of NS; however, a single presumptive factor has not been defined yet. Extended evidence obtained by advances in the pathobiology of podocytes has implicated podocytes as critical regulator of glomerular protein filtration and podocytopathy. The candidate molecules as pathological mediators of steroid-dependent NS are CD80 (also known as B7-1), hemopexin, and angiopoietin-like 4. The "two-hit" hypothesis proposes that the expression of CD80 on podocytes and ineffective inhibition of podocyte CD80 due to regulatory T-cell dysfunction or impaired autoregulation by podocytes results in NS. Recent studies suggest that not only T cells but also other immune cells and podocytes are involved in the pathogenesis of MCNS.

• Biomedical Science Letters
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• v.12 no.3
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• pp.217-224
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• 2006

It has been reported that the dysfunctions of podocytes are associated with the development of diabetic nephropathy. In addition, insulin-like growth factors (IGFs) are associated with the development of diabetic nephropathy. However, it is not yet known about the effect of high glucose on IGF-I, -II secretion, and IGF binding proteins (IGFBPs) expression in the podocytes. Thus, this study was conducted to examine the effect of high glucose on IGF system and its involvement of protein kinase C (PKC) and mitogen activated protein kinases (MAPKs) in podocytes. In this study, high glucose (25 mM) increased IGF-I and IGF-II secretion (P<0.05), which was blocked by SB 203580 (a p38 MAPK inhibitor) but not by PD 98059 (a p44/42 MAPK inhibitor). In addition, high glucose-induced stimulation of IGFs was blocked by bisindolylmaleimide I and staurosporine (protein kinase C inhibitors). High glucose also increased IGFBP-l expression, which was blocked by bisindolylmaleimide I and SB 203580. In conclusion, high glucose alters IGFs secretion and IGFBP expression via PKC and p38 MAPK pathways in podocytes.

• Clinical and Experimental Pediatrics
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• v.55 no.10
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• pp.371-376
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• 2012

Purpose: Puromycin aminonucleoside (PAN) specifically injures podocytes, leading to foot process effacement, actin cytoskeleton disorganization, and abnormal distribution of slit diaphragm proteins. p130Cas is a docking protein connecting F-actin fibers to the glomerular basement membrane (GBM) and adapter proteins in glomerular epithelial cells (GEpCs; podocytes). We investigated the changes in the p130Cas expression level in the PAN-induced pathological changes of podocytes in vitro. Methods: We observed changes in the p130Cas expression in cultured rat GEpCs and mouse podocytes treated with various concentrations of PAN and antioxidants, including probucol, epigallocatechin gallate (EGCG), and vitamin C. The changes in the p130Cas expression level were analyzed using confocal immunofluorescence imaging, Western blotting, and polymerase chain reaction. Results: In the immunofluorescence study, p130Cas showed a diffuse cytoplasmic distribution with accumulation at distinct sites visible as short stripes and colocalized with P-cadherin. The fluorescences of the p130Cas protein were internalized and became granular by PAN administration in a dose-dependent manner, which had been restored by antioxidants, EGCG and vitamin C. PAN also decreased the protein and mRNA expression levels of p130Cas at high doses and in a longer exposed duration, which had been also reversed by antioxidants. Conclusion: These findings suggest that PAN modulates the quantitative and distributional changes of podocyte p130Cas through oxidative stress resulting in podocyte dysfunction.

• Journal of Ginseng Research
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• v.37 no.1
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• pp.94-99
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• 2013

Proteinuric conditions demonstrate structural and compositional changes of the foot processes and slit diaphragms between podocytes. p130Cas in podocytes serves as an adapter protein anchoring glomerular basement membrane to actin filaments of podocyte cytoskeleton. To investigate the effect of ginseng total saponin (GTS) on the pathologic changes of podocyte p130Cas induced by diabetic conditions, we cultured mouse podocytes under: 1) normal glucose (5 mM, control); 2) high glucose (HG, 30 mM); 3) advanced glycosylation endproducts (AGE)-added; or 4) HG plus AGE-added conditions and treated with GTS. In confocal imaging, p130Cas colocalized with zonula occludens-1 and synaptopodin connecting to F-actin. However, diabetic conditions relocalized p130Cas molecules at perinuclear cytoplasmic area and reduced the intensity of p130Cas. In Western blotting, diabetic conditions, especially HG plus AGE-added condition, decreased cellular p130Cas protein levels at 24 and 48 h. GTS improved such quantitative and qualitative changes. These findings imply that HG and AGE have an influence on the redistribution and amount of p130Cas of podocytes, which can be reversed by GTS.

• Journal of Ginseng Research
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• v.38 no.4
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• pp.233-238
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• 2014

Background: The actin cytoskeleton in podocytes is essential for the maintenance of its normal structure and function. Its disruption is a feature of podocyte foot-process effacement and is associated with proteinuria. ${\alpha}$-Actinin-4 in podocytes serves as a linker protein binding the actin filaments of the cytoskeleton. Methods: To investigate the effect of ginseng total saponin (GTS) on the pathological changes of podocyte ${\alpha}$-actinin-4 induced by diabetic conditions, we cultured mouse podocytes under normal glucose (5mM) or high glucose (HG, 30mM) conditions, with or without the addition of advanced glycosylation end products (AGE), and treated with GTS. Results: In confocal imaging, ${\alpha}$-actinin-4 colocalized with the ends of F-actin fibers in cytoplasm, but diabetic conditions disrupted F-actin fibers and concentrated ${\alpha}$-actinin-4 molecules at the peripheral cytoplasm. GTS upregulated ${\alpha}$-actinin protein in a time- and dose-dependent manner, and suppressed the receptor for AGE levels in western blotting. Diabetic conditions, including HG, AGE, and both together, decreased cellular ${\alpha}$-actinin-4 protein levels at 24 h and 48 h. Such quantitative and qualitative changes of ${\alpha}$-actinin-4 protein induced by diabetic conditions were mitigated by GTS. Conclusion: These findings imply that both HG and AGE have an influence on the distribution and amount of ${\alpha}$-actinin-4 in podocytes that can be recovered by GTS.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.400-407
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• 2023

Background: Rb3 is a ginsenoside with anti-inflammatory properties in many cell types and has been reported to attenuate inflammation-related metabolic diseases such as insulin resistance, nonalcoholic fatty liver disease, and cardiovascular disease. However, the effect of Rb3 on podocyte apoptosis under hyperlipidemic conditions, which contributes to the development of obesity-mediated renal disease, remains unclear. In the current study, we aimed to investigate the effect of Rb3 on podocyte apoptosis in the presence of palmitate and explore its underlying molecular mechanisms. Methods: Human podocytes (CIHP-1 cells) were exposed to Rb3 in the presence of palmitate as a model of hyperlipidemia. Cell viability was assessed by MTT assay. The effects of Rb3 on the expression of various proteins were analyzed by Western blotting. Apoptosis levels were determined by MTT assay, caspase 3 activity assay, and cleaved caspase 3 expression. Results: We found that Rb3 treatment alleviated the impairment of cell viability and increased caspase 3 activity as well as inflammatory markers in palmitate-treated podocytes. Treatment with Rb3 dosedependently increased PPARδ and SIRT6 expression. Knockdown of PPARδ or SIRT6 reduced the effects of Rb3 on apoptosis as well as inflammation and oxidative stress in cultured podocytes. Conclusions: The current results suggest that Rb3 alleviates inflammation and oxidative stress via PPARδ-or SIRT6-mediated signaling, thereby attenuating apoptosis in podocytes in the presence of palmitate. The present study provides Rb3 as an effective strategy for treating obesity-mediated renal injury.

• Clinical and Experimental Pediatrics
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• v.64 no.7
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• pp.355-363
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• 2021

Background: Nephrotic syndrome (NS) is a common renal disorder in children attributed to podocyte injury. However, children with the same diagnosis have markedly variable treatment responses, clinical courses, and outcomes, suggesting molecular heterogeneity. Purpose: This study aimed to explore the molecular responses of podocytes to nephrotic plasma to identify specific genes and signaling pathways differentiating various clinical NS groups as well as biological processes that drive injury in normal podocytes. Methods: Transcriptome profiles from immortalized human podocyte cell line exposed to the plasma of 8 subjects (steroid-sensitive nephrotic syndrome [SSNS], n=4; steroid-resistant nephrotic syndrome [SRNS], n=2; and healthy adult individuals [control], n=2) were generated using microarray analysis. Results: Unsupervised hierarchical clustering of global gene expression data was broadly correlated with the clinical classification of NS. Differential gene expression (DGE) analysis of diseased groups (SSNS or SRNS) versus healthy controls identified 105 genes (58 up-regulated, 47 down-regulated) in SSNS and 139 genes (78 up-regulated, 61 down-regulated) in SRNS with 55 common to SSNS and SRNS, while the rest were unique (50 in SSNS, 84 genes in SRNS). Pathway analysis of the significant (P≤0.05, -1≤ log2 FC ≥1) differentially expressed genes identified the transforming growth factor-β and Janus kinase-signal transducer and activator of transcription pathways to be involved in both SSNS and SRNS. DGE analysis of SSNS versus SRNS identified 2,350 genes with values of P≤0.05, and a heatmap of corresponding expression values of these genes in each subject showed clear differences in SSNS and SRNS. Conclusion: Our study observations indicate that, although podocyte injury follows similar pathways in different clinical subgroups, the pathways are modulated differently as evidenced by the heatmap. Such transcriptome profiling with a larger cohort can stratify patients into intrinsic subtypes and provide insight into the molecular mechanisms of podocyte injury.

• Journal of Life Science
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• v.8 no.4
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• pp.449-456
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• 1998

Using morphometric technique, the present study was made of the kidney of rabbit embryo in the 13 days of the gestation. Their section areas of the renal tubules and the glomerular cells were compared with the those of adult rabbit, 1. In the developing renal tubule, the tubular section areas were larger than that of the adult, but the nuclear section areas of tubular calls were smaller than the adult. The microvilli of their cell surface were poorly developed, and their cytoplasm contained well developed mitochondria with euchromatic nucleus. 2. In the developing glomeruli. the nuclear section area of the cells of the parietal layer, the podocytes, and the endothelial cells were similar size, but their nuclei were larger than those of the adult. The cytopalsm of the podocytes contained well-developed rough endoplasmic reticulum, Golgi apparatus, and round mitochondria.

• Clinical and Experimental Pediatrics
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• v.60 no.3
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• pp.55-63
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• 2017

Advances in podocytology and genetic techniques have expanded our understanding of the pathogenesis of hereditary steroid-resistant nephrotic syndrome (SRNS). In the past 20 years, over 45 genetic mutations have been identified in patients with hereditary SRNS. Genetic mutations on structural and functional molecules in podocytes can lead to serious injury in the podocytes themselves and in adjacent structures, causing sclerotic lesions such as focal segmental glomerulosclerosis or diffuse mesangial sclerosis. This paper provides an update on the current knowledge of podocyte genes involved in the development of hereditary nephrotic syndrome and, thereby, reviews genotype-phenotype correlations to propose an approach for appropriate mutational screening based on clinical aspects.