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de Cos M, Mosoyan G, Chauhan K, Troost JP, Wong JS, Lefferts S, Morgan P, Meliambro K, Egerman M, Ray J, Parker T, Levine D, Seshan S, Bardash Y, Horowitz B, Kent CA, Shaw MM, Perlman A, Moledina DG, Coca SG, Campbell KN. Urinary Plasminogen as a Marker of Disease Progression in Human Glomerular Disease. Am J Kidney Dis 2024; 84:205-214.e1. [PMID: 38452919 PMCID: PMC11260534 DOI: 10.1053/j.ajkd.2024.01.520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 12/27/2023] [Accepted: 01/12/2024] [Indexed: 03/09/2024]
Abstract
RATIONALE & OBJECTIVE Glomerular disorders have a highly variable clinical course, and biomarkers that reflect the molecular mechanisms underlying their progression are needed. Based on our previous work identifying plasminogen as a direct cause of podocyte injury, we designed this study to test the association between urine plasmin(ogen) (ie, plasmin and its precursor plasminogen) and end-stage kidney disease (ESKD). STUDY DESIGN Multicenter cohort study. SETTING & PARTICIPANTS 1,010 patients enrolled in the CureGN Cohort with biopsy-proven glomerular disease (focal segmental glomerulosclerosis, membranous nephropathy, and immunoglobulin A nephropathy). PREDICTORS The main predictor was urine plasmin(ogen) at baseline. Levels were measured by an electrochemiluminescent immunoassay developed de novo. Traditional clinical and analytical characteristics were used for adjustment. The ratio of urine plasmin(ogen)/expected plasmin(ogen) was evaluated as a predictor in a separate model. OUTCOME Progression to ESKD. ANALYTICAL APPROACH Cox regression was used to examine the association between urinary plasmin(ogen) and time to ESKD. Urinary markers were log2 transformed to approximate normal distribution and normalized to urinary creatinine (Log2uPlasminogen/cr, Log2 urinary protein/cr [UPCR]). Expected plasmin(ogen) was calculated by multiple linear regression. RESULTS Adjusted Log2uPlasminogen/cr was significantly associated with ESKD (HR per doubling Log2 uPlasminogen/cr 1.31 [95% CI, 1.22-1.40], P<0.001). Comparison of the predictive performance of the models including Log2 uPlasminogen/cr, Log2 UPCR, or both markers showed the plasmin(ogen) model superiority. The ratio of measured/expected urine plasmin(ogen) was independently associated with ESKD: HR, 0.41 (95% CI, 0.22-0.77) if ratio<0.8 and HR 2.42 (95% CI, 1.54-3.78) if ratio>1.1 (compared with ratio between 0.8 and 1.1). LIMITATIONS Single plasmin(ogen) determination does not allow for the study of changes over time. The use of a cohort of mostly white patients and the restriction to patients with 3 glomerular disorders limits the external validity of our analysis. CONCLUSIONS Urinary plasmin(ogen) and the ratio of measured/expected plasmin(ogen) are independently associated with ESKD in a cohort of patients with glomerular disease. Taken together with our previous experimental findings, urinary plasmin(ogen) could be a useful biomarker in prognostic decision making and a target for the development of novel therapies in patients with proteinuria and glomerular disease. PLAIN-LANGUAGE SUMMARY Glomerular diseases are an important cause of morbidity and mortality in patients of all ages. Knowing the individual risk of progression to dialysis or transplantation would help to plan the follow-up and treatment of these patients. Our work studies the usefulness of urinary plasminogen as a marker of progression in this context, since previous studies indicate that plasminogen may be involved in the mechanisms responsible for the progression of these disorders. Our work in a sample of 1,010 patients with glomerular disease demonstrates that urinary plasminogen (as well as the ratio of measured to expected plasminogen) is associated with the risk of progression to end-stage kidney disease. Urine plasminogen exhibited good performance and, if further validated, could enable risk stratification for timely interventions in patients with proteinuria and glomerular disease.
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Affiliation(s)
- Marina de Cos
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Gohar Mosoyan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kinsuk Chauhan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jonathan P Troost
- Michigan Institute for Clinical and Health Research, University of Michigan, Ann Arbor, Michigan
| | - Jenny S Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Sean Lefferts
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Paul Morgan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kristin Meliambro
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Marc Egerman
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Justina Ray
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Tom Parker
- Rogosin Institute, Weill Cornell Medicine, New York, New York
| | - Daniel Levine
- Rogosin Institute, Weill Cornell Medicine, New York, New York
| | - Surya Seshan
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York
| | - Yoni Bardash
- St. Joseph's University Medical, Paterson, New Jersey
| | - Benjamin Horowitz
- Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey
| | - Candice A Kent
- Section of Nephrology and Clinical and Translational Research Accelerator, Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut
| | - Melissa M Shaw
- Section of Nephrology and Clinical and Translational Research Accelerator, Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut
| | - Alan Perlman
- Rogosin Institute, Weill Cornell Medicine, New York, New York; Division of Nephrology and Hypertension, Department of Medicine, Weill Cornell Medicine, New York, New York
| | - Dennis G Moledina
- Section of Nephrology and Clinical and Translational Research Accelerator, Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut
| | - Steven G Coca
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kirk N Campbell
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
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Tojo A, Abe M, Matsuyama KI. Direct observation of epoxy resin blocks for renal biopsy by low-vacuum scanning electron microscopy. Med Mol Morphol 2023; 56:206-216. [PMID: 37165248 PMCID: PMC10415507 DOI: 10.1007/s00795-023-00356-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/26/2023] [Indexed: 05/12/2023]
Abstract
To improve the resolution of low-vacuum scanning electron microscopy (LVSEM), the epoxy resin block for the transmission electron microscopy (TEM) was observed directly with LVSEM. After observing ultrathin sections from renal biopsies of IgA nephropathy, membranous nephropathy, lupus nephritis, diabetic nephropathy (DM), thin basement membrane disease (TBMD), Alport's syndrome, Fabry's disease, and renal amyloidosis, the epoxy resin blocks of the same sites were observed by LVSEM and compared. The LVSEM image of the epoxy resin block corresponds to the negative of the TEM image, and when the gradation is reversed, the LVSEM image was comparable to the TEM image. At a low magnification of 100 ×, the entire specimen, including the glomerulus, was obtained. LVSEM at 5000 × magnification was sufficient to identify paramesangial deposits in IgA nephropathy and subepithelial electron-dense deposits (EDD) and spikes in membranous nephropathy. Glomerular basement membrane thickening in DM and thinning in TBMD could be sufficiently diagnosed with LVSEM at 6000 ×. Accumulation of ceramide in Fabry's disease was easily identified, but amyloid fibril could not be identified by LVSEM. LVSEM of renal biopsy epoxy resin blocks can replace TEM up to moderate magnification.
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Affiliation(s)
- Akihiro Tojo
- Department of Nephrology and Hypertension, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Tochigi, 321-0293, Japan.
| | - Makoto Abe
- Department of Nephrology and Hypertension, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Tochigi, 321-0293, Japan
| | - Kin-Ichi Matsuyama
- Department of Diagnostic Pathology, Dokkyo Medical University, Mibu, Tochigi, Japan
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Urinary Podocyte Excretion Predicts Urinary Protein Selectivity and Renal Prognosis. Int J Nephrol 2022; 2022:2702651. [PMID: 35866051 PMCID: PMC9296344 DOI: 10.1155/2022/2702651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/11/2022] [Indexed: 11/17/2022] Open
Abstract
Background Urinary podocyte excretion is related to a reduction in glomerular podocyte numbers, glomerulosclerosis, and urinary protein selectivity. To elucidate the role of urinary podocytes in proteinuria and renal prognosis and to identify the factors that cause podocyte detachment, we examined urinary podocytes in 120 renal biopsy patients. Methods Podocytes were identified in urinary sediments stained with fluorescent-labeled anti-podocalyxin antibodies in ten high power fields. The amounts of protein bands, separated by SDS-polyacrylamide gel electrophoresis, were calculated using an image software program and the correlation with urinary podocytes was analyzed. Podocyte surface pores were observed using a low-vacuum scanning electron microscope. The renal prognosis, including induction of hemodialysis or 30% reduction in eGFR, was investigated. Results Urinary podocyte excretion showed a higher positive correlation with albumin excretion compared to IgG, prealbumin, and transferrin. There were no significant correlations between urinary podocyte count and low molecular weight proteins, including β2-microglobulin and α1-microglobulin. The number of podocyte surface pores was positively correlated with proteinuria, suggesting enhanced albumin transcytosis. The hemodynamic pressure on the glomerular capillary wall, including products of pulse pressure and pulse rate (water hammer pressure), was positively correlated with urinary podocyte excretion. Urinary podocyte excretion and Tamm–Horsfall protein (THP) were independent risk factors for renal prognosis but were not related to response to treatment. Conclusion Urinary podocyte excretion was correlated with urinary albumin excretion, indicating specific albumin transport by podocytes. Podocytes were detached from the glomerular capillaries by water hammer pressure and THP was involved in the renal prognosis.
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Yen NTH, Park SM, Thu VTA, Phat NK, Cho YS, Yoon S, Shin JG, Kim DH, Oh JH, Long NP. Genome-wide gene expression analysis reveals molecular insights into the drug-induced toxicity of nephrotoxic agents. Life Sci 2022; 306:120801. [PMID: 35850247 DOI: 10.1016/j.lfs.2022.120801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/30/2022] [Accepted: 07/09/2022] [Indexed: 11/17/2022]
Abstract
Drug-induced nephrotoxicity is frequently reported. However, the mechanisms underlying nephrotoxic medications and their overlapping molecular events, which might have therapeutic value, are unclear. We performed a genome-wide analysis of gene expression and a gene set enrichment analysis to identify common and unique pathways associated with the toxicity of colistin, ifosfamide, indomethacin, and puromycin. Rats were randomly allocated into the treatment or control group. The treatment group received a toxic dose once daily of each investigated drug for 1 week. Differentially expressed genes were found in the drug-treated kidney and liver compared to the control, except for colistin in the liver. Upregulated pathways were mainly related to cell death, cell cycle, protein synthesis, and immune response modulation in the kidney. Cell cycle was upregulated by all drugs. Downregulated pathways were associated with carbon metabolism, amino acid metabolism, and fatty acid metabolism. Indomethacin, colistin, and puromycin shared the most altered pathways in the kidney. Ifosfamide and indomethacin affected molecular processes greatly in the liver. Our findings provide insight into the mechanisms underlying the renal and hepatic adverse effects of the four drugs. Further investigation should explore the combinatory drug therapies that attenuate the toxic effects and maximize the effectiveness of nephrotoxic drugs.
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Affiliation(s)
- Nguyen Thi Hai Yen
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Se-Myo Park
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea
| | - Vo Thuy Anh Thu
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Nguyen Ky Phat
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Yong-Soon Cho
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Seokjoo Yoon
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea
| | - Jae-Gook Shin
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Dong Hyun Kim
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea
| | - Jung-Hwa Oh
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon 34114, Republic of Korea.
| | - Nguyen Phuoc Long
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 614-735, Republic of Korea; Center for Personalized Precision Medicine of Tuberculosis, Inje University College of Medicine, Busan 614-735, Republic of Korea.
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Hatakeyama S, Tojo A, Satonaka H, Yamada NO, Senda T, Ishimitsu T. Decreased Podocyte Vesicle Transcytosis and Albuminuria in APC C-Terminal Deficiency Mice with Puromycin-Induced Nephrotic Syndrome. Int J Mol Sci 2021; 22:ijms222413412. [PMID: 34948207 PMCID: PMC8708520 DOI: 10.3390/ijms222413412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
In minimal change nephrotic syndrome, podocyte vesicle transport is enhanced. Adenomatous polyposis coli (APC) anchors microtubules to cell membranes and plays an important role in vesicle transport. To clarify the role of APC in vesicle transport in podocytes, nephrotic syndrome was induced by puromycin amino nucleoside (PAN) injection in mice expressing APC1638T lacking the C-terminal of microtubule-binding site (APC1638T mouse); this was examined in renal tissue changes. The kidney size and glomerular area of APC1638T mice were reduced (p = 0.014); however, the number of podocytes was same between wild-type (WT) mice and APC1638T mice. The ultrastructure of podocyte foot process was normal by electron microscopy. When nephrotic syndrome was induced, the kidneys of WT+PAN mice became swollen with many hyaline casts, whereas these changes were inhibited in the kidneys of APC1638T+PAN mice. Electron microscopy showed foot process effacement in both groups; however, APC1638T+PAN mice had fewer vesicles in the basal area of podocytes than WT+PAN mice. Cytoplasmic dynein-1, a motor protein for vesicle transport, and α-tubulin were significantly reduced in APC1638T+PAN mice associated with suppressed urinary albumin excretion compared to WT+PAN mice. In conclusion, APC1638T mice showed reduced albuminuria associated with suppressed podocyte vesicle transport when minimal change nephrotic syndrome was induced.
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Affiliation(s)
- Saaya Hatakeyama
- Department of Nephrology & Hypertension, Dokkyo Medical University, Tochigi 321-0293, Japan; (S.H.); (H.S.); (T.I.)
| | - Akihiro Tojo
- Department of Nephrology & Hypertension, Dokkyo Medical University, Tochigi 321-0293, Japan; (S.H.); (H.S.); (T.I.)
- Correspondence: ; Tel.: +81-282-86-1111
| | - Hiroshi Satonaka
- Department of Nephrology & Hypertension, Dokkyo Medical University, Tochigi 321-0293, Japan; (S.H.); (H.S.); (T.I.)
| | - Nami O. Yamada
- Department of Anatomy, Gifu University, Gifu 501-1193, Japan; (N.O.Y.); (T.S.)
| | - Takao Senda
- Department of Anatomy, Gifu University, Gifu 501-1193, Japan; (N.O.Y.); (T.S.)
| | - Toshihiko Ishimitsu
- Department of Nephrology & Hypertension, Dokkyo Medical University, Tochigi 321-0293, Japan; (S.H.); (H.S.); (T.I.)
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Moriyama T, Hasegawa F, Miyabe Y, Akiyama K, Karasawa K, Uchida K, Nitta K. Intracellular trafficking pathway of albumin in glomerular epithelial cells. Biochem Biophys Res Commun 2021; 574:97-103. [PMID: 34450430 DOI: 10.1016/j.bbrc.2021.08.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 08/18/2021] [Indexed: 10/20/2022]
Abstract
The intracellular trafficking pathway of albumin in podocytes remains controversial. We therefore analysed albumin endocytosis through caveolae, subsequent transcytosis, and exocytosis. In Western blot and immunofluorescence analysis in vitro, methyl-beta-cyclodextrin (MBCD) treatment significantly decreased the expression of caveolin-1 and albumin in cultured human podocytes after incubation with albumin; additionally, MBCD interfered with albumin endocytosis through caveolae in the experiment using Transwell plates. In the immunofluorescence analysis, albumin was incubated with cultured human podocytes, and colocalisation analysis with organelles and cytoskeletons in the podocytes showed that albumin particles colocalised with caveolin-1 and Fc-receptor but not clathrin in endocytosis, colocalised with actin cytoskeleton but not microtubules in transcytosis, and colocalised with early endosomes and lysosomes but not proteasome, endoplasmic reticulum, or Golgi apparatus. In the electron microscopic analysis of podocytes in nephrotic syndrome model mice, gold-labelled albumin was shown as endocytosis, transcytosis, and exocytosis with caveolae. These results indicate the intracellular trafficking of albumin through podocytes. Albumin enters through caveolae with the Fc-receptor, moves along actin, and reaches the early endosome, where some of them are sorted for lysosomal degradation, and others are directly transported outside the cells through exocytosis. This intracellular pathway may be a new aetiological hypothesis for albuminuria.
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Affiliation(s)
- Takahito Moriyama
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Fumio Hasegawa
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Yoei Miyabe
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Kenichi Akiyama
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Kazunori Karasawa
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Keiko Uchida
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
| | - Kosaku Nitta
- Department of Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
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Huang LM, Mao JH. Glomerular podocyte dysfunction in inherited renal tubular disease. World J Pediatr 2021; 17:227-233. [PMID: 33625696 PMCID: PMC8253710 DOI: 10.1007/s12519-021-00417-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 01/20/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Hereditary renal tubular disease can cause hypercalciuria, acid-base imbalance, hypokalemia, hypomagnesemia, rickets, kidney stones, etc. If these diseases are not diagnosed or treated in time, they can cause kidney damage and electrolyte disturbances, which can be detrimental to the maturation and development of the child. Glomerular involvement in renal tubular disease patients has only been considered recently. METHODS We screened 71 papers (including experimental research, clinical research, etc.) about Dent's disease, Gitelman syndrome, and cystinosis from PubMed, and made reference. RESULTS Glomerular disease was initially underestimated among the clinical signs of renal tubular disease or was treated merely as a consequence of the tubular damage. Renal tubular diseases affect glomerular podocytes through certain mechanisms resulting in functional damage, morphological changes, and glomerular lesions. CONCLUSIONS This article focuses on the progress of changes in glomerular podocyte function in Dent disease, Gitelman syndrome, and cystinosis for the purposes of facilitating clinically accurate diagnosis and scientific treatment and improving prognosis.
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Affiliation(s)
- Li-Min Huang
- Department of Nephrology, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou 310006, China
| | - Jian-Hua Mao
- Department of Nephrology, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou 310006, China.
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Egerman MA, Wong JS, Runxia T, Mosoyan G, Chauhan K, Reyes-Bahamonde J, Anandakrishnan N, Wong NJ, Bagiella E, Salem F, Meliambro K, Li H, Azeloglu EU, Coca SG, Campbell KN, Raij L. Plasminogenuria is associated with podocyte injury, edema, and kidney dysfunction in incident glomerular disease. FASEB J 2020; 34:16191-16204. [PMID: 33070369 PMCID: PMC7686123 DOI: 10.1096/fj.202000413r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 01/07/2023]
Abstract
Urinary plasminogen/plasmin, or plasmin (ogen) uria, has been demonstrated in proteinuric patients and exposure of cultured podocytes to plasminogen results in injury via oxidative stress pathways. A causative role for plasmin (ogen) as a "second hit" in kidney disease progression has yet to have been demonstrated in vivo. Additionally, association between plasmin (ogen) uria and kidney function in glomerular diseases remains unclear. We performed comparative studies in a puromycin aminonucleoside (PAN) nephropathy rat model treated with amiloride, an inhibitor of plasminogen activation, and measured changes in plasmin (ogen) uria. In a glomerular disease biorepository cohort (n = 128), we measured time-of-biopsy albuminuria, proteinuria, and plasmin (ogen) uria for correlations with kidney outcomes. In cultured human podocytes, plasminogen treatment was associated with decreased focal adhesion marker expression with rescue by amiloride. Increased glomerular plasmin (ogen) was found in PAN rats and focal segmental glomerulosclerosis (FSGS) patients. PAN nephropathy was associated with increases in plasmin (ogen) uria and proteinuria. Amiloride was protective against PAN-induced glomerular injury, reducing CD36 scavenger receptor expression and oxidative stress. In patients, we found associations between plasmin (ogen) uria and edema status as well as eGFR. Our study demonstrates a role for plasmin (ogen)-induced podocyte injury in the PAN nephropathy model, with amiloride having podocyte-protective properties. In one of the largest glomerular disease cohorts to study plasminogen, we validated previous findings while suggesting a potentially novel relationship between plasmin (ogen) uria and estimated glomerular filtration rate (eGFR). Together, these findings suggest a role for plasmin (ogen) in mediating glomerular injury and as a viable targetable biomarker for podocyte-sparing treatments.
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Affiliation(s)
- Marc A. Egerman
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Jenny S. Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Tian Runxia
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine
| | - Gohar Mosoyan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Kinsuk Chauhan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | | | | | - Nicholas J. Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Emilia Bagiella
- Center for Biostatistics, Department of Population health Science and Policy, Icahn School of Medicine at Mount Sinai
| | - Fadi Salem
- Department of Pathology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Kristin Meliambro
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Hong Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School
| | - Evren U. Azeloglu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai
| | - Steven G. Coca
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Kirk N. Campbell
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Leopoldo Raij
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine
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TRPV4 promotes acoustic wave-mediated BBB opening via Ca 2+/PKC-δ pathway. J Adv Res 2020; 26:15-28. [PMID: 33133680 PMCID: PMC7584681 DOI: 10.1016/j.jare.2020.06.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 05/14/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Introduction Numerous studies have shown the ability of low-energy acoustic waves such as focused ultrasound or shockwave to transiently open blood-brain barrier (BBB) and facilitate drug delivery to the brain. Preclinical and clinical evidences have well demonstrated the efficacy and safety in treating various brain disorders. However, the molecular mechanisms of acoustic waves on the BBB are still not fully understood. Objectives The present study aimed at exploring the possible molecular mechanisms of acoustic wave stimulation on brains. Methods: Briefly describe the experimental design The left hemisphere of the rat‘s brain was treated with pulsed ultrasound from a commercial focused shockwave or a planar ultrasound device, and the right hemisphere served as a control. One hour after the mechanical wave stimulation or overnight, the rats were sacrificed and the brains were harvested for protein or histological analysis. Agonists and antagonists related to the signal transduction pathways of tight junction proteins were used to investigate the possible intracellular mechanisms. Results Intracellular signal transduction analysis shows calcium influx through transient receptor potential vanilloid 4 (TRPV4) channels, and the activation of PKC-δ pathway to mediate dissociation of ZO-1 and occludin after acoustic wave stimulation. The activation of TRPV4 or PKC-δ signaling further increased the expression level of TRPV4, suggesting a feedback loop to regulate BBB permeability. Moreover, the tight junction proteins dissociation can be reversed by administration of PKC-δ inhibitor and TRPV4 antagonist. Conclusion The present study shows the crucial role of TRPV4 in acoustic wave-mediated BBB permeability, specifically its effect on compromising tight junction proteins, ZO-1 and occludin. Our findings provide a new molecular perspective to explain acoustic wave-mediated BBB opening. Moreover, activation of TRPV4 by agonists may reduce the threshold intensity level of acoustic waves for BBB opening, which may prevent undesirable mechanical damages while maintaining efficient BBB opening.
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Shen H, Bao Y, Feng C, Fu H, Mao J. Overexpression of Myo1e promotes albumin endocytosis by mouse glomerular podocytes mediated by Dynamin. PeerJ 2020; 8:e8599. [PMID: 32211226 PMCID: PMC7083160 DOI: 10.7717/peerj.8599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/19/2020] [Indexed: 11/20/2022] Open
Abstract
Background As a fundamental process internalizing molecules from the plasma membrane, endocytosis plays a crucial role in podocyte biology. Our previous study has identified that overexpression of Myole may enhance podocyte endocytosis. However, its potential mechanism has been not well understand. Thus, we aimed to analyze whether albumin endocytosis by mouse glomerular podocytes is dependent on Myo1e expression. Also, we aimed to elucidate whether the underlying mechanism is mediated by Dynamin. Methods Firstly, mouse podocyte cells (MPC5) were treated with different concentrations of FITC-bovine serum albumin (BSA). The fluorescence intensity and cell viability were detected by flow cytometry and MTT assays, respectively. Afterwards, the optimal concentration of FITC-BSA was determined. Secondly, MPC5 cells were treated with Myole overexpression or knockdown. Cell morphology was observed under microscope. Immunofluorescence assay was used to determine the expression of F-actin. The protein expression of nephrin and podocin was detected by western blot. Flow cytometry was used to detect MPC5 cell apoptosis with annexin V. Finally, MPC5 cells were treated with Myole overexpression and/or Dynasore (a GTPase inhibitor of Dynamin). The fluorescence intensity was detected using flow cytometry assay. Results MPC5 endocytosis BSA was elevated with a concentration-dependent manner. MTT results showed that MPC5 cell viability was inhibited with a concentration-dependent manner. Myo1e overexpression promoted podocyte endocytic FITC-BSA, which was contrary to its knockdown. Under microscope, after inhibition of Myo1e, podocyte foot process fusion was observed. Myo1e overexpression promoted the expression of cytoskeleton F-actin and podocyte-specific molecules (nephrin and podocin) in podocyte endocytic FITC-BSA. Furthermore, we found that Myo1e promoted the apoptosis of podocytes. Dynasore attenuated the increase in endocytosis of FITC-BSA induced by Myo1e overexpression, suggesting that podocytes might mediate albumin endocytosis via Myo1e-Dynamin-Albumin. Conclusion Our findings revealed that overexpression of Myo1e promotes albumin endocytosis in mouse glomerular podocyte endocytic albumin mediated by Dynamin.
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Affiliation(s)
- Huijun Shen
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yu Bao
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Chunyue Feng
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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11
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Three-dimensional imaging of podocyte ultrastructure using FE-SEM and FIB-SEM tomography. Cell Tissue Res 2019; 379:245-254. [DOI: 10.1007/s00441-019-03118-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/26/2019] [Indexed: 11/25/2022]
Abstract
AbstractPodocytes are specialized epithelial cells used for glomerular filtration in the kidney. They can be divided into the cell body, primary process and foot process. Here, we describe two useful methods for the three-dimensional(3D) visualization of these subcellular compartments in rodent podocytes. The first method, field-emission scanning electron microscopy (FE-SEM) with conductive staining, is used to visualize the luminal surface of numerous podocytes simultaneously. The second method, focused-ion beam SEM (FIB-SEM) tomography, allows the user to obtain serial images from different depths of field, or Z-stacks, of the glomerulus. This allows for the 3D reconstruction of podocyte ultrastructure, which can be viewed from all angles, from a single image set. This is not possible with conventional FE-SEM. The different advantages and disadvantages of FE-SEM and FIB-SEM tomography compensate for the weaknesses of the other. The combination renders a powerful approach for the 3D analysis of podocyte ultrastructure. As a result, we were able to identify a new subcellular compartment of podocytes, “ridge-like prominences” (RLPs).
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12
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Mechanism Underlying Selective Albuminuria in Minimal Change Nephrotic Syndrome. Int J Nephrol 2019; 2019:5859102. [PMID: 31781392 PMCID: PMC6874928 DOI: 10.1155/2019/5859102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/24/2019] [Indexed: 01/04/2023] Open
Abstract
As water and solutes are filtered through the slit membrane, it is an a priori concept that a slit membrane is an essential filtration barrier for proteins, including albumin. However, in cases of minimal change nephrotic syndrome, the number of slit membranes is reduced by the foot process effacement and tight junction-like cell adhesion. Furthermore, albumin endocytosis is enhanced in the podocytes under condition of minimal change disease, and albumin is selectively transported by the albumin receptor FcRn. Suppressing the endocytosis of albumin with anti-FcRn antibody decreases the urinary protein level. The expression of motor molecules, such as cytoplasmic dynein 1 and myosin IX, is increased in the podocytes under conditions of minimal change nephrotic syndrome, suggesting the enhanced transport of vesicles containing albumin. Podocyte vesicle transport may play an important role in the pathology of selective albuminuria in cases of nephrotic syndrome.
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13
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Fernandez-Fernandez B, Izquierdo MC, Valiño-Rivas L, Nastou D, Sanz AB, Ortiz A, Sanchez-Niño MD. Albumin downregulates Klotho in tubular cells. Nephrol Dial Transplant 2019; 33:1712-1722. [PMID: 29425318 DOI: 10.1093/ndt/gfx376] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Background Kidney tubular cells are the main sources of Klotho, a protein with phosphaturic action. Genetic Klotho deficiency causes premature cardiovascular aging in mice. Human chronic kidney disease (CKD) is characterized by acquired Klotho deficiency. Despite the lack of uremic toxin accumulation, Category G1 CKD [(normal glomerular filtration rate (GFR)] is already associated with decreased Klotho and with premature cardiovascular aging. Methods We have explored whether albuminuria, a criterion to diagnose CKD when GFR is normal, may directly decrease Klotho expression in human CKD, preclinical models and cultured tubular cells. Results In a CKD cohort, albuminuria correlated with serum phosphate after adjustment for GFR, age and sex. In this regard, urinary Klotho was decreased in patients with pathological albuminuria but preserved GFR. Proteinuria induced in rats by puromycin aminonucleoside and in mice by albumin overload was associated with interstitial inflammation and reduced total kidney Klotho messenger ribonucleic acid (mRNA) expression. Western blot disclosed reduced kidney Klotho protein in proteinuric rats and mice and immunohistochemistry localized the reduced kidney Klotho expression to tubular cells in proteinuric animals. In cultured murine and human tubular cells, albumin directly decreased Klotho mRNA and protein expression. This was inhibited by trichostatin A, an inhibitor of histone deacetylases, but unlike cytokine-induced Klotho downregulation, not by inhibitors of nuclear factor kappa-light-chain-enhancer of activated B cells. Conclusions In conclusion, albumin directly decreases Klotho expression in cultured tubular cells. This may explain, or at least contribute to, the decrease in Klotho and promote fibroblast growth factor 23 resistance in early CKD categories, as observed in preclinical and clinical proteinuric kidney disease.
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Affiliation(s)
- Beatriz Fernandez-Fernandez
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,Fundación Renal Iñigo Alvarez de Toledo-IRSIN, Madrid, Spain and.,REDINREN, Madrid, Spain
| | - M Concepcion Izquierdo
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,Fundación Renal Iñigo Alvarez de Toledo-IRSIN, Madrid, Spain and.,REDINREN, Madrid, Spain
| | - Lara Valiño-Rivas
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,Fundación Renal Iñigo Alvarez de Toledo-IRSIN, Madrid, Spain and.,REDINREN, Madrid, Spain
| | - Dimitra Nastou
- Department of Nephrology, General Hospital of Syros, Syros, Greece
| | - Ana B Sanz
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,Fundación Renal Iñigo Alvarez de Toledo-IRSIN, Madrid, Spain and.,REDINREN, Madrid, Spain
| | - Alberto Ortiz
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,REDINREN, Madrid, Spain
| | - Maria D Sanchez-Niño
- Department of Nephrology, IIS-Fundación Jiménez Díaz-Universidad Autónoma de Madrid, Madrid, Spain.,Fundación Renal Iñigo Alvarez de Toledo-IRSIN, Madrid, Spain and.,REDINREN, Madrid, Spain
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14
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Differential trafficking of albumin and IgG facilitated by the neonatal Fc receptor in podocytes in vitro and in vivo. PLoS One 2019; 14:e0209732. [PMID: 30811433 PMCID: PMC6392300 DOI: 10.1371/journal.pone.0209732] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/12/2019] [Indexed: 12/26/2022] Open
Abstract
Proteinuria is strongly associated with kidney disease progression but the mechanisms underlying podocyte handling of serum proteins such as albumin and IgG remain to be elucidated. We have previously shown that albumin and IgG are transcytosed by podocytes in vitro. In other epithelial cells, the neonatal Fc receptor (FcRn) is required to salvage albumin and IgG from the degradative pathway thereby allowing these proteins to be transcytosed or recycled. Here we directly examine the role of FcRn in albumin and IgG trafficking in podocytes by studying handling of these proteins in FcRn knockout (KO) podocytes in vitro and in a podocyte-specific FcRn knockout mice in vivo. In vitro, we find that knockout of FcRn leads to IgG accumulation in podocytes but does not alter albumin trafficking. Similarly, in vivo, podocyte-specific knockout of FcRn does not result in albumin accumulation in podocytes in vivo as measured by mean albumin fluorescence intensity whereas these mice demonstrate significant intraglomerular accumulation of IgG over time. In addition we find that podocyte-specific FcRn KO mice demonstrate mesangial expansion as they age and activation of mesangial cells as demonstrated by increased expression of α-smooth muscle actin. Taken together, these results suggest that trafficking pathways for albumin and IgG differ in podocytes and that sustained disruption of trafficking of plasma proteins alters glomerular structure.
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15
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3D organoid-derived human glomeruli for personalised podocyte disease modelling and drug screening. Nat Commun 2018; 9:5167. [PMID: 30514835 PMCID: PMC6279764 DOI: 10.1038/s41467-018-07594-z] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 11/05/2018] [Indexed: 12/11/2022] Open
Abstract
The podocytes within the glomeruli of the kidney maintain the filtration barrier by forming interdigitating foot processes with intervening slit diaphragms, disruption in which results in proteinuria. Studies into human podocytopathies to date have employed primary or immortalised podocyte cell lines cultured in 2D. Here we compare 3D human glomeruli sieved from induced pluripotent stem cell-derived kidney organoids with conditionally immortalised human podocyte cell lines, revealing improved podocyte-specific gene expression, maintenance in vitro of polarised protein localisation and an improved glomerular basement membrane matrisome compared to 2D cultures. Organoid-derived glomeruli retain marker expression in culture for 96 h, proving amenable to toxicity screening. In addition, 3D organoid glomeruli from a congenital nephrotic syndrome patient with compound heterozygous NPHS1 mutations reveal reduced protein levels of both NEPHRIN and PODOCIN. Hence, human iPSC-derived organoid glomeruli represent an accessible approach to the in vitro modelling of human podocytopathies and screening for podocyte toxicity. Studies examining human podocytopathies have utilised 2D cultured primary or immortalised podocyte cell lines. Here, the authors demonstrate that 3D human glomeruli sieved from induced pluripotent stem cell-derived kidney organoids retain an improved podocyte identity in vitro facilitating disease modelling and toxicity testing.
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16
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Maha A. Correlation between reabsorbed intracytoplasmic proteins in glomerular podocytes and the level of proteinuria in patients with glomerulopathies. Ultrastruct Pathol 2018; 42:489-497. [PMID: 30383481 DOI: 10.1080/01913123.2018.1536686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Podocytes can handle proteins when the glomerular filtration barrier is injured with leak of proteins out of the vasculature into the urine. The correlation between the number of podocytes involved in handling leaked proteins, as well as the extent of up-taken proteins in podocytes cytoplasm on one side, and the level of proteinuria in the concerned patients on the other side, is evaluated. A retrospective study of 22 patients with clinical proteinuria caused by various glomerulopathies was retrieved and analyzed. The glomerulopathies in the concerned patients were pathologically diagnosed through microscopic examination of the submitted renal biopsies over a period extending from January, 2013 to December, 2016. Additionally, three cases with protein levels in urine within the acceptable normal range were also analyzed as controls. Electron microscopic examination of the glomerular podocytes in the relevant cases constituted the base for the present study. Among the studied cases, it was noted that the greater the number of glomerular podocytes with reabsorbed proteins within the cytoplasm, the lower the level of proteinuria. Comparatively, cases with fewer numbers of podocytes with reabsorbed proteins disclosed higher levels of proteinuria. The present study might be the first to shed light on the correlation between morphologically recognizable glomerular podocytes with reabsorbed proteins and the level of proteinuria in patients with various glomerulopathies. The current study may constitute a base for the future research work concerned with the structural changes of glomerular podocytes as an adaptive mechanism in cases of proteinuria.
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Affiliation(s)
- Arafah Maha
- a Department of Pathology , College of Medicine King Saud University , Riyadh , Kingdom of Saudi Arabia
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17
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Min SY, Ha DS, Ha TS. Puromycin aminonucleoside triggers apoptosis in podocytes by inducing endoplasmic reticulum stress. Kidney Res Clin Pract 2018; 37:210-221. [PMID: 30254845 PMCID: PMC6147198 DOI: 10.23876/j.krcp.2018.37.3.210] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 05/14/2018] [Accepted: 06/26/2018] [Indexed: 01/13/2023] Open
Abstract
Background Puromycin aminonucleoside (PAN) is a known podocytotoxin. PAN-induced nephrosis is a widely used animal model for studying human idiopathic nephrotic syndrome. Abnormal protein accumulation associated with podocyte-specific endoplasmic reticulum (ER) stress damages cells structurally and functionally, which in turn induces apoptosis and severe proteinuria. In the present study, we investigated the effect of PAN on ER stress and apoptosis in podocytes in vitro. Methods Mouse podocytes were cultured and treated with various concentrations of PAN. ER stress markers were then evaluated by western blotting, and apoptosis was evaluated by fluorescence-activated cell sorting (FACS) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays. Results PAN treatment increased ER stress markers such as activating transcription factor (ATF) 6α and caspase-12 in a dose-dependent manner at 12 and 24 hours, respectively. These markers were reduced by chemical chaperones, such as sodium 4-phenylbutyric acid and tauroursodeoxycholic acid. PAN treatment also increased 78 kD glucose-regulated protein (GRP78)/binding immunoglobulin protein (BiP) at the earlier stage of 12 hours. PAN significantly induced podocyte apoptosis in concentration- and time-dependent manners, as seen using FACS and TUNEL assays. This result was improved by Nox4 siRNA, ATF6 siRNA, and chemical chaperones. LY294002, a PI3-kinase inhibitor, significantly boosted ER stress and apoptosis. PAN-induced ER stress increased oxidative stress and subsequently induced apoptosis, and could be mitigated by inhibition of PI3-kinase signaling. Conclusion Our findings suggest that PAN induces ER stress in podocytes mainly through the GRP78/BiP, ATF6α, and caspase-12 pathways, which trigger apoptosis via induction of oxidative stress. This stress is mitigated by inhibiting PI3-kinase signaling.
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Affiliation(s)
- Seo-Yun Min
- Department of Pediatrics, Chungbuk National University College of Medicine, Cheongju, Korea
| | - Dong-Soo Ha
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Tae-Sun Ha
- Department of Pediatrics, Chungbuk National University College of Medicine, Cheongju, Korea
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18
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Gianesello L, Priante G, Ceol M, Radu CM, Saleem MA, Simioni P, Terrin L, Anglani F, Del Prete D. Albumin uptake in human podocytes: a possible role for the cubilin-amnionless (CUBAM) complex. Sci Rep 2017; 7:13705. [PMID: 29057905 PMCID: PMC5651885 DOI: 10.1038/s41598-017-13789-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 10/02/2017] [Indexed: 12/23/2022] Open
Abstract
Albumin re-uptake is a receptor-mediated pathway located in renal proximal tubuli. There is increasing evidence of glomerular protein handling by podocytes, but little is known about the mechanism behind this process. In this study, we found that human podocytes in vitro are committed to internalizing albumin through a receptor-mediated mechanism even after exposure to low doses of albumin. We show that these cells express cubilin, megalin, ClC-5, amnionless and Dab2, which are partners in the tubular machinery. Exposing human podocytes to albumin overload prompted an increase in CUBILIN, AMNIONLESS and CLCN5 gene expression. Inhibiting cubilin led to a reduction in albumin uptake, highlighting its importance in this mechanism. We demonstrated that human podocytes are committed to performing endocytosis via a receptor-mediated mechanism even in the presence of low doses of albumin. We also disclosed that protein overload first acts on the expression of the cubilin-amnionless (CUBAM) complex in these cells, then involves the ClC-5 channel, providing the first evidence for a possible role of the CUBAM complex in albumin endocytosis in human podocytes.
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Affiliation(s)
- Lisa Gianesello
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Giovanna Priante
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Monica Ceol
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Claudia M Radu
- Thrombotic and Hemorrhagic Diseases Unit, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Moin A Saleem
- Academic and Children's Renal Unit, Dorothy Hodgkin Building, BS8 1TH, Bristol, United Kingdom
| | - Paolo Simioni
- Thrombotic and Hemorrhagic Diseases Unit, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Liliana Terrin
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Franca Anglani
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy
| | - Dorella Del Prete
- Clinical Nephrology, Department of Medicine - DIMED, University of Padua, 35129, Padua, Italy.
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19
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Role of albumin and its modifications in glomerular injury. Pflugers Arch 2017; 469:975-982. [PMID: 28735420 DOI: 10.1007/s00424-017-2029-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/05/2017] [Indexed: 02/06/2023]
Abstract
Albuminuria is both a characteristic hallmark and a known risk factor for progressive glomerular disease. Although the molecular basis for a potential causative role for albuminuria in progressive chronic kidney disease remains poorly understood, there have been several recent advances in our understanding of the role of albumin, and its molecular modifications, in the development and progression of glomerular disease. This review discusses recent findings related to the ability of albumin and its associated factors to directly induce podocyte and glomerular injury. Additional recent studies confirming the ability and mechanisms by which podocytes endocytose albumin are also discussed. Lastly, we present several known molecular modifications in the albumin molecule itself, as well as substances bound to it, which may be important and potentially clinically relevant mediators of albumin-induced glomerular injury. These recent findings may create entirely new opportunities to develop novel future therapies directed at albumin that could potentially help reduce podocyte and renal tubular injury and slow the progression of chronic glomerular disease.
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20
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Argyropoulos CP, Chen SS, Ng YH, Roumelioti ME, Shaffi K, Singh PP, Tzamaloukas AH. Rediscovering Beta-2 Microglobulin As a Biomarker across the Spectrum of Kidney Diseases. Front Med (Lausanne) 2017; 4:73. [PMID: 28664159 PMCID: PMC5471312 DOI: 10.3389/fmed.2017.00073] [Citation(s) in RCA: 158] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/26/2017] [Indexed: 12/28/2022] Open
Abstract
There is currently an unmet need for better biomarkers across the spectrum of renal diseases. In this paper, we revisit the role of beta-2 microglobulin (β2M) as a biomarker in patients with chronic kidney disease and end-stage renal disease. Prior to reviewing the numerous clinical studies in the area, we describe the basic biology of β2M, focusing in particular on its role in maintaining the serum albumin levels and reclaiming the albumin in tubular fluid through the actions of the neonatal Fc receptor. Disorders of abnormal β2M function arise as a result of altered binding of β2M to its protein cofactors and the clinical manifestations are exemplified by rare human genetic conditions and mice knockouts. We highlight the utility of β2M as a predictor of renal function and clinical outcomes in recent large database studies against predictions made by recently developed whole body population kinetic models. Furthermore, we discuss recent animal data suggesting that contrary to textbook dogma urinary β2M may be a marker for glomerular rather than tubular pathology. We review the existing literature about β2M as a biomarker in patients receiving renal replacement therapy, with particular emphasis on large outcome trials. We note emerging proteomic data suggesting that β2M is a promising marker of chronic allograft nephropathy. Finally, we present data about the role of β2M as a biomarker in a number of non-renal diseases. The goal of this comprehensive review is to direct attention to the multifaceted role of β2M as a biomarker, and its exciting biology in order to propose the next steps required to bring this recently rediscovered biomarker into the twenty-first century.
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Affiliation(s)
- Christos P Argyropoulos
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Shan Shan Chen
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Yue-Harn Ng
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Maria-Eleni Roumelioti
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Kamran Shaffi
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Pooja P Singh
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Antonios H Tzamaloukas
- Nephrology Division, Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States.,Raymond G. Murphy VA Medical Center Albuquerque, Albuquerque, NM, United States
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21
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Moriyama T, Sasaki K, Karasawa K, Uchida K, Nitta K. Intracellular transcytosis of albumin in glomerular endothelial cells after endocytosis through caveolae. J Cell Physiol 2017; 232:3565-3573. [DOI: 10.1002/jcp.25817] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/20/2017] [Accepted: 01/20/2017] [Indexed: 02/02/2023]
Affiliation(s)
- Takahito Moriyama
- Department of Medicine; Kidney Center; Tokyo Women's Medical University; Tokyo Japan
| | - Kayo Sasaki
- Department of Medicine; Kidney Center; Tokyo Women's Medical University; Tokyo Japan
| | - Kazunori Karasawa
- Department of Medicine; Kidney Center; Tokyo Women's Medical University; Tokyo Japan
| | - Keiko Uchida
- Department of Medicine; Kidney Center; Tokyo Women's Medical University; Tokyo Japan
| | - Kosaku Nitta
- Department of Medicine; Kidney Center; Tokyo Women's Medical University; Tokyo Japan
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22
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Kitai M, Fukuda N, Ueno T, Endo M, Maruyama T, Abe M, Okada K, Soma M, Matsumoto K. Effects of a spleen tyrosine kinase inhibitor on progression of the lupus nephritis in mice. J Pharmacol Sci 2017; 134:29-36. [PMID: 28479222 DOI: 10.1016/j.jphs.2017.02.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 02/13/2017] [Accepted: 02/22/2017] [Indexed: 01/14/2023] Open
Abstract
The Fc receptors (FcR) have pivotal roles in the pathogenesis of the autoimmune glomerulonephritis. We therefore investigated the effects of a Syk inhibitor on the progression of lupus nephritis and SH3 domain binding protein 2 and p38MAP kinase signalings in mice. NZB/W F1 mice, a model of lupus nephritis, received a Syk inhibitor R406. Western blotting and immunohistochemistry revealed that R406 treatment significantly delayed the appearance of proteinuria, histologically improved their glomerulosclerosis and inhibited the increased the expression of MCP-1 and TGF-β1 mRNAs and the nephrin and podocin proteins in the kidney. The treatment suppressed the phosphorylation of 3BP2 in white blood cells from the spleen and significantly inhibited the phosphorylation of p38MAPK in the kidney but did not affect expression of neonatal Fc receptor. These findings indicate the important roles and mechanisms of Fcγ receptors I and III in the development of autoimmune glomerulonephritis and suggest the possible application of Syk inhibitors as novel medicines for the glomerulonephritis.
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Affiliation(s)
- Maki Kitai
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Noboru Fukuda
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan; Research Center of Nihon University, Tokyo, Japan.
| | - Takahiro Ueno
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Morito Endo
- Faculty of Human Health Science, Hachinohe Gakuin University, Hachinohe, Aomori, Japan
| | - Takashi Maruyama
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Masanori Abe
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Kazuyoshi Okada
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Masayoshi Soma
- Division of General Medicine, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Koichi Matsumoto
- Division of Nephrology Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
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23
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Tojo A, Hatakeyama S, Kinugasa S, Fukuda S, Sakai T. Enhanced podocyte vesicle transport in the nephrotic rat. Med Mol Morphol 2017; 50:86-93. [DOI: 10.1007/s00795-016-0151-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 12/19/2016] [Indexed: 01/27/2023]
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24
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Castrop H, Schießl IM. Novel routes of albumin passage across the glomerular filtration barrier. Acta Physiol (Oxf) 2017; 219:544-553. [PMID: 27452481 DOI: 10.1111/apha.12760] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/13/2016] [Accepted: 07/20/2016] [Indexed: 12/20/2022]
Abstract
Albuminuria is a hallmark of kidney diseases of various aetiologies and an unambiguous symptom of the compromised integrity of the glomerular filtration barrier. Furthermore, there is increasing evidence that albuminuria per se aggravates the development and progression of chronic kidney disease. This review covers new aspects of the movement of large plasma proteins across the glomerular filtration barrier in health and disease. Specifically, this review focuses on the role of endocytosis and transcytosis of albumin by podocytes, which constitutes a new pathway of plasma proteins across the filtration barrier. Thus, we summarize what is known about the mechanisms of albumin endocytosis by podocytes and address the fate of the endocytosed albumin, which is directed to lysosomal degradation or transcellular movement with subsequent vesicular release into the urinary space. We also address the functional consequences of overt albumin endocytosis by podocytes, such as the formation of pro-inflammatory cytokines, which might eventually result in a deterioration of podocyte function. Finally, we consider the diagnostic potential of podocyte-derived albumin-containing vesicles in the urine as an early marker of a compromised glomerular barrier function. In terms of new technical approaches, the review covers how our knowledge of the movement of albumin across the glomerular filtration barrier has expanded by the use of new intravital imaging techniques.
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Affiliation(s)
- H. Castrop
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - I. M. Schießl
- Institute of Physiology; University of Regensburg; Regensburg Germany
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25
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Zhang K, Liu Y, Liu X, Chen J, Cai Q, Wang J, Huang H. Apocynin improving cardiac remodeling in chronic renal failure disease is associated with up-regulation of epoxyeicosatrienoic acids. Oncotarget 2016; 6:24699-708. [PMID: 26322503 PMCID: PMC4694789 DOI: 10.18632/oncotarget.5084] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/07/2015] [Indexed: 12/28/2022] Open
Abstract
Cardiac remodeling is one of the most common cardiac abnormalities and associated with a high mortality in chronic renal failure (CRF) patients. Apocynin, a nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase inhibitor, has been showed cardio-protective effects. However, whether apocynin can improve cardiac remodeling in CRF and what is the underlying mechanism are unclear. In the present study, we enrolled 94 participants. In addition, we used 5/6 nephrectomized rats to mimic cardiac remodeling in CRF. Serum levels of epoxyeicosatrienoic acids (EETs) and its mainly metabolic enzyme-soluble epoxide hydrolase (sEH) were measured. The results showed that the serum levels of EETs were significantly decreased in renocardiac syndrome participants (P < 0.05). In 5/6 nephrectomized CRF model, the ratio of left ventricular weight / body weight, left ventricular posterior wall thickness, and cardiac interstitial fibrosis were significantly increased while ejection fraction significantly decreased (P < 0.05). All these effects could partly be reversed by apocynin. Meanwhile, we found during the process of cardiac remodeling in CRF, apocynin significantly increased the reduced serum levels of EETs and decreased the mRNA and protein expressions of sEH in the heart (P < 0.05). Our findings indicated that the protective effect of apocynin on cardiac remodeling in CRF was associated with the up-regulation of EETs. EETs may be a new mediator for the injury of kidney-heart interactions.
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Affiliation(s)
- Kun Zhang
- Department of Cardiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.,Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Yu Liu
- Department of Cardiology, the People's Hospital of Guangxi Zhuang Autonomous Region, Nanning 530000, China
| | - Xiaoqiang Liu
- Department of Clinical Laboratory, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Jie Chen
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China.,Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Qingqing Cai
- Department of Medical Oncology, Sun Yat-Sen University Cancer Center, Sun Yat-Sen University, Guangzhou 510120, China
| | - Jingfeng Wang
- Department of Cardiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.,Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
| | - Hui Huang
- Department of Cardiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.,Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou 510120, China
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26
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Yuan Y, Zhao C, An X, Wu L, Wang H, Zhao M, Bai M, Duan S, Zhang B, Zhang A, Xing C. A vital role for myosin-9 in puromycin aminonucleoside-induced podocyte injury by affecting actin cytoskeleton. Free Radic Res 2016; 50:627-37. [PMID: 26902808 DOI: 10.3109/10715762.2016.1155706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Yanggang Yuan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Chuanyan Zhao
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Xiaofei An
- Department of Endocrinology, Jiangsu Province Hospital of Chinese Medicine, Nanjing, China
| | - Lin Wu
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Hui Wang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Min Zhao
- Department of Nephrology, Nanjing Children’s Hospital, Nanjing Medical University, Nanjing, China
| | - Mi Bai
- Department of Nephrology, Nanjing Children’s Hospital, Nanjing Medical University, Nanjing, China
| | - Suyan Duan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Bo Zhang
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Aihua Zhang
- Department of Nephrology, Nanjing Children’s Hospital, Nanjing Medical University, Nanjing, China
- Institute of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Changying Xing
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
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27
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Venkatareddy M, Verma R, Kalinowski A, Patel SR, Shisheva A, Garg P. Distinct Requirements for Vacuolar Protein Sorting 34 Downstream Effector Phosphatidylinositol 3-Phosphate 5-Kinase in Podocytes Versus Proximal Tubular Cells. J Am Soc Nephrol 2016; 27:2702-19. [PMID: 26825532 DOI: 10.1681/asn.2015050555] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 12/09/2015] [Indexed: 12/16/2022] Open
Abstract
The mechanisms by which the glomerular filtration barrier prevents the loss of large macromolecules and simultaneously, maintains the filter remain poorly understood. Recent studies proposed that podocytes have an active role in both the endocytosis of filtered macromolecules and the maintenance of the filtration barrier. Deletion of a key endosomal trafficking regulator, the class 3 phosphatidylinositol (PtdIns) 3-kinase vacuolar protein sorting 34 (Vps34), in podocytes results in aberrant endosomal membrane morphology and podocyte dysfunction. We recently showed that the vacuolation phenotype in cultured Vps34-deficient podocytes is caused by the absence of a substrate for the Vps34 downstream effector PtdIns 3-phosphate 5-kinase (PIKfyve), which phosphorylates Vps34-generated PtdIns(3)P to produce PtdIns (3,5)P2. PIKfyve perturbation and PtdIns(3,5)P2 reduction result in massive membrane vacuolation along the endosomal system, but the cell-specific functions of PIKfyve in vivo remain unclear. We show here that the genetic deletion of PIKfyve in endocytically active proximal tubular cells resulted in the development of large cytoplasmic vacuoles caused by arrested endocytic traffic progression at a late-endosome stage. In contrast, deletion of PIKfyve in glomerular podocytes did not significantly alter the endosomal morphology, even in age 18-month-old mice. However, on culturing, the PIKfyve-deleted podocytes developed massive cytoplasmic vacuoles. In summary, these data suggest that glomerular podocytes and proximal tubules have different requirements for PIKfyve function, likely related to distinct in vivo needs for endocytic flux.
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Affiliation(s)
- Madhusudan Venkatareddy
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Rakesh Verma
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Anne Kalinowski
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Sanjeevkumar R Patel
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Puneet Garg
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan; and
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28
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Ha TS, Park HY, Seong SB, Ahn HY. Puromycin aminonucleoside increases podocyte permeability by modulating ZO-1 in an oxidative stress-dependent manner. Exp Cell Res 2015; 340:139-49. [PMID: 26683996 DOI: 10.1016/j.yexcr.2015.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/17/2015] [Accepted: 12/08/2015] [Indexed: 11/30/2022]
Abstract
Puromycin aminonucleoside (PAN)-induced nephrosis is a widely studied animal model of human idiopathic nephrotic syndrome because PAN injection into rats results in increased glomerular permeability with the characteristic ultrastructural changes in podocytes similar to human nephrosis. To investigate the role of zonula occludens (ZO)-1 and oxidative stress on PAN-induced podocyte phenotypical changes and hyperpermeability in vitro, we cultured rat and mouse podocytes and treated with various concentrations of PAN. PAN treatment increased oxidative stress level of podocytes significantly with the induction of Nox4. In addition, PAN changed the ultrastructure of podocytes, such as shortening and fusion of microvilli, and the separation of intercellular gaps, which were improved by anti-oxidative vitamin C and Nox4 siRNA. PAN also disrupted the intercellular linear ZO-1 staining and induced inner cytoplasmic re-localization of ZO-1 protein, resulting in increased podocyte intercellular permeability. PAN reduced ZO-1 protein amount and mRNA expression in a dose-dependent manner, which means that PAN could also modulate ZO-1 protein transcriptionally. However, the decreased ZO-1 protein of podocytes by PAN was improved by Nox4 siRNA transfection. Furthermore, vitamin C mitigated the quantitative and distributional disturbances of ZO-1 protein caused by PAN. Our results demonstrate that the phenotypical changes of intercellular ZO-1 by oxidative stress via Nox4 likely contribute to the glomerular hyperpermeability caused by PAN.
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Affiliation(s)
- Tae-Sun Ha
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea.
| | - Hye-Young Park
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Su-Bin Seong
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, South Korea
| | - Hee Yul Ahn
- Department of Pharmacology, College of Medicine, Chungbuk National University, Cheongju, South Korea
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29
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Bhatti AB, Usman M. Drug Targets for Oxidative Podocyte Injury in Diabetic Nephropathy. Cureus 2015; 7:e393. [PMID: 26798569 PMCID: PMC4699926 DOI: 10.7759/cureus.393] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 11/30/2015] [Indexed: 12/19/2022] Open
Abstract
Diabetic nephropathy (DN) is one the most prevalent chronic complications of diabetes mellitus that affects as much as one-third of diabetic patients irrespective of the type of diabetes. Hyperglycemia is the key trigger for DN that initiates a number of microscopic and ultramicroscopic changes in kidney architecture. Microscopic changes include thickening of the glomerular basement membrane (GBM), tubular basement membrane (TBM), mesangial proliferation, arteriosclerosis, and glomerulotubular junction abnormalities (GTJA). Among the ultramicroscopic changes, effacement of podocytes and decrease in their density seem to be the centerpiece of DN pathogenesis. These changes in kidney architecture then produce functional deficits, such as microalbuminuria and decreased glomerular filtration rate (GFR). Among several mechanisms involved in inflicting damage to podocytes, injuries sustained by increased oxidative stress turns out to be the most important mechanism. Different variables that are included in increased production of reactive oxygen species (ROS) include a hyperglycemia-induced reduction in glutathione (GSH), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation via hyperglycemia, advanced glycation end products (AGEs), protein kinase C (PKC), and renin-angiotensin-aldosterone system (RAAS). Unfortunately, control of podocyte injury hasn't received much attention as a treatment approach for DN. Therefore, this review article is mainly concerned with the exploration of various treatment options that might help in decreasing the podocyte injury, mainly by reducing the level of NADPH oxidase-mediated generation of ROS. This article concludes with a view that certain NADPH oxidase inhibitors, RAAS inhibitors, statins, antidiabetic drugs, and antioxidant vitamins might be useful in decreasing podocyte injury and resultant structural and functional kidney impairments in DN.
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Affiliation(s)
- Adnan Bashir Bhatti
- Department of Medicine, Capital Development Authority Hospital, Islamabad, Pakistan
| | - Muhammad Usman
- Department of Medicine, Jinnah Hospital Lahore (JHL)/Allama Iqbal Medical College (AIMC), Lahore, Pakistan
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30
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Eriguchi M, Yotsueda R, Torisu K, Kawai Y, Hasegawa S, Tanaka S, Noguchi H, Masutani K, Kitazono T, Tsuruya K. Assessment of urinary angiotensinogen as a marker of podocyte injury in proteinuric nephropathies. Am J Physiol Renal Physiol 2015; 310:F322-33. [PMID: 26632605 DOI: 10.1152/ajprenal.00260.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/01/2015] [Indexed: 01/13/2023] Open
Abstract
Urinary protein (UP) is widely used as a clinical marker for podocyte injury; however, not all proteinuric nephropathies fit this model. We previously described the elevation of urinary angiotensinogen (AGT) accompanied by AGT expression by injured podocytes in a nitric oxide inhibition rat model (Eriguchi M, Tsuruya K, Haruyama N, Yamada S, Tanaka S, Suehiro T, Noguchi H, Masutani K, Torisu K, Kitazono T. Kidney Int 87: 116-127, 2015). In this report, we performed the human and animal studies to examine the significance and origin of urinary AGT. In the human study, focal segmental glomerulosclerosis (FSGS) patients presented with higher levels of urinary AGT, corrected by UP, than minimal-change disease (MCD) patients. Furthermore, AGT was evident in podocin-negative glomerular segmental lesions. We also tested two different nephrotic models induced by puromycin aminonucleoside in Wistar rats. The urinary AGT/UP ratio and AGT protein and mRNA expression in sieved glomeruli from FSGS rats were significantly higher than in MCD rats. The presence of AGT at injured podocytes in FSGS rats was detected by immunohistochemistry and immunoelectron microscopy. Finally, we observed the renal tissue and urinary metabolism of exogenous injected human recombinant AGT (which is not cleaved by rodent renin) in FSGS and control rats. Significant amounts of human AGT were detected in the urine of FSGS rats, but not of control rats. Immunostaining for rat and human AGT identified that only rat AGT was detected in injured podocytes, and filtered human AGT was seen in superficial proximal tubules, but not in injured podocytes, suggesting AGT generation by injured podocytes. In conclusion, the urinary AGT/UP ratio represents a novel specific marker of podocyte injury.
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Affiliation(s)
- Masahiro Eriguchi
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Ryusuke Yotsueda
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Kumiko Torisu
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Yasuhiro Kawai
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Shoko Hasegawa
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Shigeru Tanaka
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Hideko Noguchi
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Kosuke Masutani
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Takanari Kitazono
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and
| | - Kazuhiko Tsuruya
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and Department of Integrated Therapy for Chronic Kidney Disease, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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31
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Dobrinskikh E, Lewis L, Brian Doctor R, Okamura K, Lee MG, Altmann C, Faubel S, Kopp JB, Blaine J. Shank2 Regulates Renal Albumin Endocytosis. Physiol Rep 2015; 3:e12510. [PMID: 26333830 PMCID: PMC4600376 DOI: 10.14814/phy2.12510] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 07/22/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022] Open
Abstract
Albuminuria is a strong and independent predictor of kidney disease progression but the mechanisms of albumin handling by the kidney remain to be fully defined. Previous studies have shown that podocytes endocytose albumin. Here we demonstrate that Shank2, a large scaffolding protein originally identified at the neuronal postsynaptic density, is expressed in podocytes in vivo and in vitro and plays an important role in albumin endocytosis in podocytes. Knockdown of Shank2 in cultured human podocytes decreased albumin uptake, but the decrease was not statistically significant likely due to residual Shank2 still present in the knockdown podocytes. Complete knockout of Shank2 in podocytes significantly diminished albumin uptake in vitro. Shank2 knockout mice develop proteinuria by 8 weeks of age. To examine albumin handling in vivo in wild-type and Shank2 knockout mice we used multiphoton intravital imaging. While FITC-labeled albumin was rapidly seen in the renal tubules of wild-type mice after injection, little albumin was seen in the tubules of Shank2 knockout mice indicating dysregulated renal albumin trafficking in the Shank2 knockouts. We have previously found that caveolin-1 is required for albumin endocytosis in cultured podocytes. Shank2 knockout mice had significantly decreased expression and altered localization of caveolin-1 in podocytes suggesting that disruption of albumin endocytosis in Shank2 knockouts is mediated via caveolin-1. In summary, we have identified Shank2 as another component of the albumin endocytic pathway in podocytes.
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Affiliation(s)
| | - Linda Lewis
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | - Kayo Okamura
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Min Goo Lee
- Department of Pharmacology, Severance Biomedical Science Institute Yonsei University College of Medicine, Seoul, Korea
| | | | - Sarah Faubel
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jeffrey B Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland
| | - Judith Blaine
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Yonekura Y, Fujii H, Nakai K, Kono K, Goto S, Shinohara M, Nishi S. Anti-oxidative effect of the β-blocker carvedilol on diabetic nephropathy in non-obese type 2 diabetic rats. Clin Exp Pharmacol Physiol 2015; 42:972-978. [PMID: 26173411 DOI: 10.1111/1440-1681.12447] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/22/2015] [Accepted: 06/22/2015] [Indexed: 11/27/2022]
Abstract
Oxidative stress plays an important role in the pathogenesis of diabetic nephropathy. The β-blocker carvedilol has been proven to have an anti-oxidant property. The aim of the present study was to elucidate the effects of carvedilol on diabetic nephropathy. At 20 weeks of age, male Spontaneously Diabetic Torii (SDT) rats were divided into three groups based on treatment: (i) an INS group (administered insulin); (ii) a CAR group (administered 10 mg/kg per day, p.o., carvedilol); and (iii) a diabetic (DM) group (administered vehicle). Rats were treated for a period of 10 weeks and were killed at 30 weeks of age. Urinary albumin excretion, renal histomorphology, and oxidative stress were evaluated. Urinary albumin excretion was significantly lower in the CAR than DM group (42.82 ± 3.94 vs 76.62 ± 13.74 mg/day respectively; P < 0.05). The mesangial index was lower in the CAR group than in the DM group. Urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG), the number of 8-OHdG-positive cells in glomeruli, and the mRNA expression of NADPH oxidase p22phox and p47phox were also lower in the CAR than DM group. However, haemoglobin A1c (HbA1c) and blood pressure levels were comparable between the two groups. The results suggest that carvedilol could prevent the progression of diabetic nephropathy by suppressing oxidative stress.
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Affiliation(s)
- Yuriko Yonekura
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hideki Fujii
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kentaro Nakai
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Keiji Kono
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shunsuke Goto
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
| | | | - Shinichi Nishi
- Division of Nephrology and Kidney Centre, Kobe University Graduate School of Medicine, Kobe, Japan
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Schießl IM, Hammer A, Kattler V, Gess B, Theilig F, Witzgall R, Castrop H. Intravital Imaging Reveals Angiotensin II-Induced Transcytosis of Albumin by Podocytes. J Am Soc Nephrol 2015; 27:731-44. [PMID: 26116357 DOI: 10.1681/asn.2014111125] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 05/11/2015] [Indexed: 11/03/2022] Open
Abstract
Albuminuria is a hallmark of kidney disease of various etiologies and usually caused by deterioration of glomerular filtration barrier integrity. We recently showed that angiotensin II (Ang II) acutely increases albumin filtration in the healthy kidney. Here, we used intravital microscopy to assess the effects of Ang II on podocyte function in rats. Acute infusion of 30, 60, or 80 ng/kg per minute Ang II enhanced the endocytosis of albumin by activation of the type 1 Ang II receptor and resulted in an average (±SEM) of 3.7±2.2, 72.3±18.6 (P<0.001), and 239.4±34.6 µm(3) (P<0.001) albumin-containing vesicles per glomerulus, respectively, compared with none at baseline or 10 ng/kg per minute Ang II. Immunostaining of Ang II-infused kidneys confirmed the presence of albumin-containing vesicles, which colocalized with megalin, in podocin-positive cells. Furthermore, podocyte endocytosis of albumin was markedly reduced in the presence of gentamicin, a competitive inhibitor of megalin-dependent endocytosis. Ang II infusion increased the concentration of albumin in the subpodocyte space, a potential source for endocytic protein uptake, and gentamicin further increased this concentration. Some endocytic vesicles were acidified and colocalized with LysoTracker. Most vesicles migrated from the capillary to the apical aspect of the podocyte and were eventually released into the urinary space. This transcytosis accounted for approximately 10% of total albumin filtration. In summary, the transcellular transport of proteins across the podocyte constitutes a new pathway of glomerular protein filtration. Ang II enhances the endocytosis and transcytosis of plasma albumin by podocytes, which may eventually impair podocyte function.
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Affiliation(s)
| | | | | | | | - Franziska Theilig
- Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany; and
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Liu Y, Liu Y, Liu X, Chen J, Zhang K, Huang F, Wang JF, Tang W, Huang H. Apocynin Attenuates Cardiac Injury in Type 4 Cardiorenal Syndrome via Suppressing Cardiac Fibroblast Growth Factor-2 With Oxidative Stress Inhibition. J Am Heart Assoc 2015; 4:JAHA.114.001598. [PMID: 26109504 PMCID: PMC4608061 DOI: 10.1161/jaha.114.001598] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background Type 4 cardiorenal syndrome (CRS) refers to the cardiac injury induced by chronic kidney disease. We aimed to assess oxidative stress and cardiac injury in patients with type 4 CRS, determine whether the antioxidant apocynin attenuated cardiac injury in rats with type 4 CRS, and explore potential mechanisms. Methods and Results A cross-sectional study was conducted among patients with type 4 CRS (n=17) and controls (n=16). Compared with controls, patients with type 4 CRS showed elevated oxidative stress, which was significantly correlated with cardiac hypertrophy and decreased ejection fraction. In vivo study, male Sprague-Dawley rats underwent 5/6 subtotal nephrectomy and sham surgery, followed with apocynin or vehicle treatment for 8 weeks. Eight weeks after surgery, the 5/6 subtotal nephrectomy rats mimicked type 4 CRS, showing increased serum creatinine, cardiac hypertrophy and fibrosis, and decreased ejection fraction compared with sham-operated animals. Cardiac malondialdehyde, NADPH oxidase activity, fibroblast growth factor-2, and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation increased significantly in the 5/6 subtotal nephrectomy rats. These changes were significantly attenuated by apocynin. In vitro study showed that apocynin reduced angiotensin II–induced NADPH oxidase–dependent oxidative stress, upregulation of fibroblast growth factor-2 and fibrosis biomarkers, and ERK1/2 phosphorylation in cardiac fibroblasts. Importantly, the ERK1/2 inhibitor U0126 reduced the upregulation of fibroblast growth factor-2 and fibrosis biomarkers in angiotensin II–treated fibroblasts. Conclusions Oxidative stress is a candidate mediator for type 4 CRS. Apocynin attenuated cardiac injury in type 4 CRS rats via inhibiting NADPH oxidase–dependent oxidative stress-activated ERK1/2 pathway and subsequent fibroblast growth factor-2 upregulation. Our study added evidence to the beneficial effect of apocynin in type 4 CRS.
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Affiliation(s)
- Yang Liu
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
| | - Yu Liu
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.) Department of Cardiology, People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, China (Y.L.)
| | - Xun Liu
- Division of Nephrology, Department of Internal Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China (X.L.)
| | - Jie Chen
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
| | - Kun Zhang
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
| | - Feifei Huang
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
| | - Jing-Feng Wang
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
| | - Wanchun Tang
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Weil Institute of Critical Care Medicine, Rancho Mirage, CA (W.T.)
| | - Hui Huang
- Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China (Y.L., J.C., K.Z., F.H., J.F.W., W.T., H.H.) Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China (Y.L., Y.L., J.C., K.Z., F.H., J.F.W., H.H.)
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Inoue K, Ishibe S. Podocyte endocytosis in the regulation of the glomerular filtration barrier. Am J Physiol Renal Physiol 2015; 309:F398-405. [PMID: 26084928 DOI: 10.1152/ajprenal.00136.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023] Open
Abstract
Severe defects in the glomerular filtration barrier result in nephrotic syndrome, which is characterized by massive proteinuria. The podocyte, a specialized epithelial cell with interdigitating foot processes separated by a slit diaphragm, plays a vital role in regulating the passage of proteins from the capillary lumen to Bowman's space. Recent findings suggest a critical role for endocytosis in podocyte biology as highlighted by genetic mouse models of disease and human genetic mutations that result in the loss of the integrity of the glomerular filtration barrier. In vitro podocyte studies have also unraveled a plethora of constituents that are differentially internalized to maintain homeostasis. These observations provide a framework and impetus for understanding the precise regulation of podocyte endocytic machinery in both health and disease.
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Affiliation(s)
- Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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Thi-Kim Vu H, Rink JC, McKinney SA, McClain M, Lakshmanaperumal N, Alexander R, Sánchez Alvarado A. Stem cells and fluid flow drive cyst formation in an invertebrate excretory organ. eLife 2015; 4:e07405. [PMID: 26057828 PMCID: PMC4500094 DOI: 10.7554/elife.07405] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 06/09/2015] [Indexed: 12/29/2022] Open
Abstract
Cystic kidney diseases (CKDs) affect millions of people worldwide. The defining pathological features are fluid-filled cysts developing from nephric tubules due to defective flow sensing, cell proliferation and differentiation. The underlying molecular mechanisms, however, remain poorly understood, and the derived excretory systems of established invertebrate models (Caenorhabditis elegans and Drosophila melanogaster) are unsuitable to model CKDs. Systematic structure/function comparisons revealed that the combination of ultrafiltration and flow-associated filtrate modification that is central to CKD etiology is remarkably conserved between the planarian excretory system and the vertebrate nephron. Consistently, both RNA-mediated genetic interference (RNAi) of planarian orthologues of human CKD genes and inhibition of tubule flow led to tubular cystogenesis that share many features with vertebrate CKDs, suggesting deep mechanistic conservation. Our results demonstrate a common evolutionary origin of animal excretory systems and establish planarians as a novel and experimentally accessible invertebrate model for the study of human kidney pathologies.
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Affiliation(s)
- Hanh Thi-Kim Vu
- Stowers Institute for Medical Research, Kansas City, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States
| | - Jochen C Rink
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sean A McKinney
- Stowers Institute for Medical Research, Kansas City, United States
| | - Melainia McClain
- Stowers Institute for Medical Research, Kansas City, United States
| | | | | | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical Research, Kansas City, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States
- Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, United States
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Chung JJ, Huber TB, Gödel M, Jarad G, Hartleben B, Kwoh C, Keil A, Karpitskiy A, Hu J, Huh CJ, Cella M, Gross RW, Miner JH, Shaw AS. Albumin-associated free fatty acids induce macropinocytosis in podocytes. J Clin Invest 2015; 125:2307-16. [PMID: 25915582 DOI: 10.1172/jci79641] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 03/19/2015] [Indexed: 01/26/2023] Open
Abstract
Podocytes are specialized epithelial cells in the kidney glomerulus that play important structural and functional roles in maintaining the filtration barrier. Nephrotic syndrome results from a breakdown of the kidney filtration barrier and is associated with proteinuria, hyperlipidemia, and edema. Additionally, podocytes undergo changes in morphology and internalize plasma proteins in response to this disorder. Here, we used fluid-phase tracers in murine models and determined that podocytes actively internalize fluid from the plasma and that the rate of internalization is increased when the filtration barrier is disrupted. In cultured podocytes, the presence of free fatty acids (FFAs) associated with serum albumin stimulated macropinocytosis through a pathway that involves FFA receptors, the Gβ/Gγ complex, and RAC1. Moreover, mice with elevated levels of plasma FFAs as the result of a high-fat diet were more susceptible to Adriamycin-induced proteinuria than were animals on standard chow. Together, these results support a model in which podocytes sense the disruption of the filtration barrier via FFAs bound to albumin and respond by enhancing fluid-phase uptake. The response to FFAs may function in the development of nephrotic syndrome by amplifying the effects of proteinuria.
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Tan RJ, Zhou D, Xiao L, Zhou L, Li Y, Bastacky SI, Oury TD, Liu Y. Extracellular Superoxide Dismutase Protects against Proteinuric Kidney Disease. J Am Soc Nephrol 2015; 26:2447-59. [PMID: 25644107 DOI: 10.1681/asn.2014060613] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 12/09/2014] [Indexed: 02/02/2023] Open
Abstract
Extracellular superoxide dismutase (EC-SOD), also known as SOD3, is an antioxidant expressed at high levels in normal adult kidneys. Because oxidative stress contributes to a variety of kidney injuries, we hypothesized that EC-SOD may be protective in CKD progression. To study this hypothesis, we used a murine model of ADR nephropathy characterized by albuminuria and renal dysfunction. We found that levels of EC-SOD diminished throughout the course of disease progression and were associated with increased levels of NADPH oxidase and oxidative stress markers. EC-SOD null mice were sensitized to ADR injury, as evidenced by increases in albuminuria, serum creatinine, histologic damage, and oxidative stress. The absence of EC-SOD led to increased levels of NADPH oxidase and an increase in β-catenin signaling, which has been shown to be pathologic in a variety of kidney injuries. Exposure of EC-SOD null mice to either chronic angiotensin II infusion or to daily albumin injections also caused increased proteinuria. In contrast, EC-SOD null mice subjected to nonproteinuric CKD induced by unilateral ureteral obstruction exhibited no differences compared with wild-type mice. Finally, we also found a decrease in EC-SOD in human CKD biopsy samples, similar to our findings in mice. Therefore, we conclude that EC-SOD is protective in CKDs characterized by proteinuria.
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Affiliation(s)
| | - Dong Zhou
- Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Liangxiang Xiao
- Division of Nephrology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Lili Zhou
- Division of Nephrology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yingjian Li
- Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Sheldon I Bastacky
- Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Tim D Oury
- Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Youhua Liu
- Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Division of Nephrology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
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Tojo A, Hatakeyama S, Kinugasa S, Nangaku M. Angiotensin receptor blocker telmisartan suppresses renal gluconeogenesis during starvation. Diabetes Metab Syndr Obes 2015; 8:103-13. [PMID: 25709483 PMCID: PMC4335621 DOI: 10.2147/dmso.s78771] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The kidney plays an important role in gluconeogenesis during starvation. To clarify the anti-diabetic action of angiotensin receptor blockers, we examined the effects of telmisartan on the sodium-glucose co-transporters (SGLT) and the pathways of renal gluconeogenesis in streptozotocin-induced diabetes mellitus (DM) rats. At 4 weeks, the DM rats treated with/without telmisartan for 2 weeks and normal control rats were used for the study after a 24-hour fast. SGLT2 expressed on the brush border membrane of the proximal convoluted tubules increased in the DM rats, but decreased in the rats treated with telmisartan. The expression of restriction enzymes of gluconeogenesis, glucose-6-phosphatase, and phosphoenolpyruvate carboxykinase increased in the proximal tubules in the DM rats, whereas these enzymes decreased in the kidneys of the rats treated with telmisartan. The elevated cytoplasmic glucose-6-phosphate and glucose levels in the kidney of DM rats significantly decreased in those treated with telmisartan, whereas those levels in the liver did not show significant change. Meanwhile, the high plasma glucose levels in the DM rats during the intravenous insulin tolerance tests were ameliorated by telmisartan. The increased fasting plasma glucose levels after 24 hours of starvation in the DM rats thus returned to the control levels by telmisartan treatment. In conclusion, the increased renal SGLT2 expression, elevated renal gluconeogenesis enzymes and extent of insulin-resistance in the DM rats were ameliorated by telmisartan therapy, thus resulting in decreased plasma glucose levels after 24 hours of fasting.
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Affiliation(s)
- Akihiro Tojo
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
- Correspondence: Akihiro Tojo, Division of Nephrology and Endocrinology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan, Tel +81 3 3815 5411 ext 37219, Fax +81 3 3814 0021, Email
| | - Saaya Hatakeyama
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Satoshi Kinugasa
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
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Eriguchi M, Tsuruya K, Haruyama N, Yamada S, Tanaka S, Suehiro T, Noguchi H, Masutani K, Torisu K, Kitazono T. Renal denervation has blood pressure-independent protective effects on kidney and heart in a rat model of chronic kidney disease. Kidney Int 2014; 87:116-27. [PMID: 24940798 DOI: 10.1038/ki.2014.220] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 05/05/2014] [Accepted: 05/08/2014] [Indexed: 12/21/2022]
Abstract
We elucidate the underlying mechanisms of bidirectional cardiorenal interaction, focusing on the sympathetic nerve driving disruption of the local renin-angiotensin system (RAS). A rat model of N(ω)-nitro-L-arginine methyl ester (L-NAME; a nitric oxide synthase inhibitor) administration was used to induce damage in the heart and kidney, similar to cardiorenal syndrome. L-NAME induced sympathetic nerve-RAS overactivity and cardiorenal injury accompanied by local RAS elevations. These were suppressed by bilateral renal denervation, but not by hydralazine treatment, despite the blood pressure being kept the same between the two groups. Although L-NAME induced angiotensinogen (AGT) protein augmentation in both organs, AGT mRNA decreased in the kidney and increased in the heart in a contradictory manner. Immunostaining for AGT suggested that renal denervation suppressed AGT onsite generation from activated resident macrophages of the heart and circulating AGT excretion from glomeruli of the kidney. We also examined rats treated with L-NAME plus unilateral denervation to confirm direct sympathetic regulation of intrarenal RAS. The levels of urinary AGT and renal angiotensin II content and the degrees of renal injury from denervated kidneys were less than those from contralateral innervated kidneys within the same rats. Thus, renal denervation has blood pressure-independent beneficial effects associated with local RAS inhibition.
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Affiliation(s)
- Masahiro Eriguchi
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kazuhiko Tsuruya
- 1] Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan [2] Department of Integrated Therapy for Chronic Kidney Disease, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Naoki Haruyama
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shunsuke Yamada
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shigeru Tanaka
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takaichi Suehiro
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hideko Noguchi
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kosuke Masutani
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kumiko Torisu
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takanari Kitazono
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Pawluczyk IZA, Pervez A, Ghaderi Najafabadi M, Saleem MA, Topham PS. The effect of albumin on podocytes: the role of the fatty acid moiety and the potential role of CD36 scavenger receptor. Exp Cell Res 2014; 326:251-8. [PMID: 24815572 DOI: 10.1016/j.yexcr.2014.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 04/07/2014] [Accepted: 04/21/2014] [Indexed: 10/25/2022]
Abstract
Evidence is emerging that podocytes are able to endocytose proteins such as albumin using kinetics consistent with a receptor-mediated process. To date the role of the fatty acid moiety on albumin uptake kinetics has not been delineated and the receptor responsible for uptake is yet to be identified. Albumin uptake studies were carried out on cultured human podocytes exposed to FITC-labelled human serum albumin either carrying fatty acids (HSA+FA) or depleted of them (HSA-FA). Receptor-mediated endocytosis of FITC-HSA+FA over 60 min was 5 times greater than that of FITC-HSA-FA. 24h exposure of podocytes to albumin up-regulated nephrin expression and induced the activation of caspase-3. These effects were more pronounced in response to HSA-FA. Individually, anti-CD36 antibodies had no effect upon endocytosis of FITC-HSA. However, a cocktail of 2 antibodies reduced uptake by nearly 50%. Albumin endocytosis was enhanced in the presence of the CD36 specific inhibitor sulfo-N-succinimidyl oleate (SSO) while knock-down of CD36 using CD36siRNA had no effect on uptake. These data suggest that receptor-mediated endocytosis of albumin by podocytes is regulated by the fatty acid moiety, although, some of the detrimental effects are induced independently of it. CD36 does not play a direct role in the uptake of albumin.
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Affiliation(s)
- I Z A Pawluczyk
- Department of Infection, Immunity and inflammation, University of Leicester, Leicester, UK; John Walls Renal Unit, Leicester General Hospital Leicester, UK.
| | - A Pervez
- Department of Infection, Immunity and inflammation, University of Leicester, Leicester, UK
| | - M Ghaderi Najafabadi
- Department of Infection, Immunity and inflammation, University of Leicester, Leicester, UK
| | - M A Saleem
- Academic and Children׳s Renal Unit, University of Bristol, Southmead Hospital, Bristol, UK
| | - P S Topham
- Department of Infection, Immunity and inflammation, University of Leicester, Leicester, UK; John Walls Renal Unit, Leicester General Hospital Leicester, UK
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Dobrinskikh E, Okamura K, Kopp JB, Doctor RB, Blaine J. Human podocytes perform polarized, caveolae-dependent albumin endocytosis. Am J Physiol Renal Physiol 2014; 306:F941-51. [PMID: 24573386 PMCID: PMC4010685 DOI: 10.1152/ajprenal.00532.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 02/26/2014] [Indexed: 11/22/2022] Open
Abstract
The renal glomerulus forms a selective filtration barrier that allows the passage of water, ions, and small solutes into the urinary space while restricting the passage of cells and macromolecules. The three layers of the glomerular filtration barrier include the vascular endothelium, glomerular basement membrane (GBM), and podocyte epithelium. Podocytes are capable of internalizing albumin and are hypothesized to clear proteins that traverse the GBM. The present study followed the fate of FITC-labeled albumin to establish the mechanisms of albumin endocytosis and processing by podocytes. Confocal imaging and total internal reflection fluorescence microscopy of immortalized human podocytes showed FITC-albumin endocytosis occurred preferentially across the basal membrane. Inhibition of clathrin-mediated endocytosis and caveolae-mediated endocytosis demonstrated that the majority of FITC-albumin entered podocytes through caveolae. Once internalized, FITC-albumin colocalized with EEA1 and LAMP1, endocytic markers, and with the neonatal Fc receptor, a marker for transcytosis. After preloading podocytes with FITC-albumin, the majority of loaded FITC-albumin was lost over the subsequent 60 min of incubation. A portion of the loss of albumin occurred via lysosomal degradation as pretreatment with leupeptin, a lysosomal protease inhibitor, partially inhibited the loss of FITC-albumin. Consistent with transcytosis of albumin, preloaded podocytes also progressively released FITC-albumin into the extracellular media. These studies confirm the ability of podocytes to endocytose albumin and provide mechanistic insight into cellular mechanisms and fates of albumin handling in podocytes.
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Affiliation(s)
- Evgenia Dobrinskikh
- Div. of Renal Diseases and Hypertension, 12700 E. 19th Ave., C281, Aurora, CO 80045.
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Miyazaki Y, Shimizu A, Pastan I, Taguchi K, Naganuma E, Suzuki T, Hosoya T, Yokoo T, Saito A, Miyata T, Yamamoto M, Matsusaka T. Keap1 inhibition attenuates glomerulosclerosis. Nephrol Dial Transplant 2014; 29:783-91. [PMID: 24523358 DOI: 10.1093/ndt/gfu002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND NFE2-related factor 2 (Nrf2) is a master regulatory transcription factor for antioxidant genes. Inhibition of its adaptor protein, Kelch-like ECH-associated protein 1 (Keap1), activates Nrf2. Podocyte injury triggers the progressive deterioration of glomerular damage toward glomerulosclerosis. We examined whether modulation of the Keap1-Nrf2 system has an impact on this process. METHODS Nrf2 null-mutant (KO) and Keap1 hypomorphic knockdown (KD) mice were crossed with NEP25 mice, in which podocyte-specific injury can be induced by an immunotoxin. RESULTS Thiobarbituric acid reactive substances, 8-hydroxydeoxyguanosine and phosphorylated JNK were increased in the injured NEP25 kidney. Real-time PCR revealed that Keap1 KD upregulated Nrf2 target genes, including Gclc, Gclm, Gstp1, Gstp2 and Nqo1 in the glomerulus. However, podocyte injury did not upregulate these genes in Keap1 wild-type mice, nor did it further increase the expression of those genes in Keap1 KD mice. Three weeks after the induction of podocyte injury, glomerulosclerosis was considerably more attenuated in Keap1 KD mice than in control mice (median sclerosis index, 0.27 versus 3.03, on a 0-4 scale). Keap1 KD mice also showed considerably preserved nephrin staining (median index, 6.76 versus 0.91, on a 0-8 scale) and decreased glomeruli containing desmin-positive injured podocytes (median percentage, 24.5% versus 85.8%), along with a decrease in mRNAs for Fn1, Tgfb1, Col4a4 and Col1a2. CONCLUSIONS Thus, podocyte injury cannot effectively activate Nrf2, but Nrf2 activation by Keap1 knockdown attenuates glomerulosclerosis. These results indicate that the Nrf2-Keap1 system is a promising drug target for the treatment of chronic kidney diseases.
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Affiliation(s)
- Yoichi Miyazaki
- Division of Kidney and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
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Müller-Deile J, Schiffer M. The podocyte power-plant disaster and its contribution to glomerulopathy. Front Endocrinol (Lausanne) 2014; 5:209. [PMID: 25566185 PMCID: PMC4266017 DOI: 10.3389/fendo.2014.00209] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 11/21/2014] [Indexed: 11/22/2022] Open
Abstract
Proper podocyte function within the glomerulus demands a high and continuous energy supply that is mainly derived from the respiratory chain of the inner mitochondrial membrane. Dysregulations in the metabolic homeostasis of podocytes may result in podocyte damage and glomerular disease. This article highlights the current knowledge about podocyte energy supply by the respiratory chain. We review the regulation of mitochondrial oxidative metabolism with regard to podocytopathy and discuss the latest understanding of different mitochondrial dysfunctions of the podocyte in diabetic nephropathy and focal segmental glomerulosclerosis (FSGS). We discuss genetic forms of mitochondriopathy of the podocyte and end with recent knowledge about crosstalk between NADH and NADPH and potential therapeutic options for podocyte mitochondriopathy. We aim to raise awareness for the complex and interesting mechanisms of podocyte damage by impaired energy supply that, despite of novel findings in recent years, is poorly understood so far.
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Affiliation(s)
- Janina Müller-Deile
- Division of Nephrology and Hypertension, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Mario Schiffer
- Division of Nephrology and Hypertension, Department of Medicine, Hannover Medical School, Hannover, Germany
- *Correspondence: Mario Schiffer, Division of Nephrology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany e-mail:
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Holterman CE, Thibodeau JF, Towaij C, Gutsol A, Montezano AC, Parks RJ, Cooper ME, Touyz RM, Kennedy CRJ. Nephropathy and elevated BP in mice with podocyte-specific NADPH oxidase 5 expression. J Am Soc Nephrol 2013; 25:784-97. [PMID: 24262797 DOI: 10.1681/asn.2013040371] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
NADPH oxidase (Nox) enzymes are a significant source of reactive oxygen species, which contribute to glomerular podocyte dysfunction. Although studies have implicated Nox1, -2, and -4 in several glomerulopathies, including diabetic nephropathy, little is known regarding the role of Nox5 in this context. We examined Nox5 expression and regulation in kidney biopsies from diabetic patients, cultured human podocytes, and a novel mouse model. Nox5 expression increased in human diabetic glomeruli compared with nondiabetic glomeruli. Stimulation with angiotensin II upregulated Nox5 expression in human podocyte cultures and increased reactive oxygen species generation. siRNA-mediated Nox5 knockdown inhibited angiotensin II-stimulated production of reactive oxygen species and altered podocyte cytoskeletal dynamics, resulting in an Rac-mediated motile phenotype. Because the Nox5 gene is absent in rodents, we generated transgenic mice expressing human Nox5 in a podocyte-specific manner (Nox5(pod+)). Nox5(pod+) mice exhibited early onset albuminuria, podocyte foot process effacement, and elevated systolic BP. Subjecting Nox5(pod+) mice to streptozotocin-induced diabetes further exacerbated these changes. Our data show that renal Nox5 is upregulated in human diabetic nephropathy and may alter filtration barrier function and systolic BP through the production of reactive oxygen species. These findings provide the first evidence that podocyte Nox5 has an important role in impaired renal function and hypertension.
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Affiliation(s)
- Chet E Holterman
- Kidney Research Centre, Division of Nephrology, Department of Medicine, and
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46
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Role of NADPH oxidase-mediated reactive oxygen species in podocyte injury. BIOMED RESEARCH INTERNATIONAL 2013; 2013:839761. [PMID: 24319690 PMCID: PMC3844218 DOI: 10.1155/2013/839761] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 09/16/2013] [Accepted: 10/04/2013] [Indexed: 02/07/2023]
Abstract
Proteinuria is an independent risk factor for end-stage renal disease (ESRD) (Shankland, 2006). Recent studies highlighted the mechanisms of podocyte injury and implications for potential treatment strategies in proteinuric kidney diseases (Zhang et al., 2012). Reactive oxygen species (ROS) are cellular signals which are closely associated with the development and progression of glomerular sclerosis. NADPH oxidase is a district enzymatic source of cellular ROS production and prominently expressed in podocytes (Zhang et al., 2010). In the last decade, it has become evident that NADPH oxidase-derived ROS overproduction is a key trigger of podocyte injury, such as renin-angiotensin-aldosterone system activation (Whaley-Connell et al., 2006), epithelial-to-mesenchymal transition (Zhang et al., 2011), and inflammatory priming (Abais et al., 2013). This review focuses on the mechanism of NADPH oxidase-mediated ROS in podocyte injury under different pathophysiological conditions. In addition, we also reviewed the therapeutic perspectives of NADPH oxidase in kidney diseases related to podocyte injury.
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47
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Mao S, Huang S. The signaling pathway of NADPH oxidase and its role in glomerular diseases. J Recept Signal Transduct Res 2013; 34:6-11. [PMID: 24156279 DOI: 10.3109/10799893.2013.848892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), a major source of reactive oxygen species, is a critical mediator of redox signaling. It is well-documented that oxidative stress is associated with the development of glomerular diseases (GN). Hence, the Nox was also thought to be involved in the pathogenesis of GN. However, the expression of Nox in various GN was not consistent, the mechanisms by which the activity of the Nox enzymes in regulating renal cells remains unclear. Signaling pathways might be very important in the pathogenesis of GN. We performed this review to provide a relatively complete signaling pathways flowchart for Nox to the investigators who were interested in the role of Nox in the pathogenesis of GN. Here, we reviewed the signal transduction pathway of Nox and its role in the pathogenesis of GN.
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Affiliation(s)
- Song Mao
- Department of Nephrology, Nanjing Children's Hospital, Nanjing Medical University , Nanjing , People's Republic of China
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48
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Urinary and glomerular podocytes in patients with chronic kidney diseases. Clin Exp Nephrol 2013; 18:95-103. [DOI: 10.1007/s10157-013-0814-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/27/2013] [Indexed: 10/26/2022]
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Sleep D, Cameron J, Evans LR. Albumin as a versatile platform for drug half-life extension. Biochim Biophys Acta Gen Subj 2013; 1830:5526-34. [PMID: 23639804 DOI: 10.1016/j.bbagen.2013.04.023] [Citation(s) in RCA: 331] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/16/2013] [Accepted: 04/17/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND Albumin is the most abundant plasma protein, is highly soluble, very stable and has an extraordinarily long circulatory half-life as a direct result of its size and interaction with the FcRn mediated recycling pathway. In contrast, many therapeutic molecules are smaller than the renal filtration threshold and are rapidly lost from the circulation thereby limiting their therapeutic potential. Albumin can be used in a variety of ways to increase the circulatory half-life of such molecules. SCOPE OF REVIEW This article will review the mechanisms which underpin albumin's extraordinarily long circulatory half-life and how the understanding of these processes are currently being employed to extend the circulatory half-life of drugs which can be engineered to bind to albumin, or are conjugated to, or genetically fused to, albumin. MAJOR CONCLUSIONS The recent and growing understanding of the pivotal role of FcRn in maintaining the extended circulatory half-life of albumin will necessitate a greater and more thorough investigation of suitable pre-clinical model systems for assessing the pharmacokinetic profiles of drugs associated, conjugated or fused to albumin. GENERAL SIGNIFICANCE Association, conjugation or fusion of therapeutic drugs to albumin is a well-accepted and established half-life extension technology. The manipulation of the albumin-FcRn interaction will facilitate the modulation of the circulatory half-life of albumin-enabled drugs, leading to superior pharmacokinetics tailored to the disease state and increased patient compliance. This article is part of a Special Issue entitled Serum Albumin.
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Kriz W, Shirato I, Nagata M, LeHir M, Lemley KV. The podocyte's response to stress: the enigma of foot process effacement. Am J Physiol Renal Physiol 2013; 304:F333-47. [DOI: 10.1152/ajprenal.00478.2012] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Progressive loss of podocytes is the most frequent cause accounting for end-stage renal failure. Podocytes are complex, terminally differentiated cells incapable of replicating. Thus lost podocytes cannot be replaced by proliferation of neighboring undamaged cells. Moreover, podocytes occupy a unique position as epithelial cells, adhering to the glomerular basement membrane (GBM) only by their processes, whereas their cell bodies float within the filtrate in Bowman's space. This exposes podocytes to the danger of being lost by detachment as viable cells from the GBM. Indeed, podocytes are continually excreted as viable cells in the urine, and the rate of excretion dramatically increases in glomerular diseases. Given this situation, it is likely that evolution has developed particular mechanisms whereby podocytes resist cell detachment. Podocytes respond to stress and injury by undergoing tremendous changes in shape. Foot process effacement is the most prominent and, yet in some ways, the most enigmatic of those changes. This review summarizes the various structural responses of podocytes to injury, focusing on foot process effacement and detachment. We raise the hypothesis that foot process effacement represents a protective response of podocytes to escape detachment from the GBM.
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Affiliation(s)
- Wilhelm Kriz
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Anatomy and Developmental Biology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Isao Shirato
- Division of Nephrology, Department of Internal Medicine, Juntendo University, School of Medicine, Tokyo, Japan
| | - Michio Nagata
- Kidney and Vascular Pathology, Faculty of Medicine, University of Tsukuba, Tsukuba-City, Japan
| | - Michel LeHir
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Kevin V. Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California
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