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Wang L, Tang Y, Buckley AF, Spurney RF. Blockade of the natriuretic peptide clearance receptor attenuates proteinuria in a mouse model of focal segmental glomerulosclerosis. Physiol Rep 2021; 9:e15095. [PMID: 34755480 PMCID: PMC8578888 DOI: 10.14814/phy2.15095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 12/31/2022] Open
Abstract
Glomerular podocytes play a key role in proteinuric diseases. Accumulating evidence suggests that cGMP signaling has podocyte protective effects. The major source of cGMP generation in podocytes is natriuretic peptides. The natriuretic peptide clearance receptor (NPRC) binds and degrades natriuretic peptides. As a result, NPRC inhibits natriuretic peptide-induced cGMP generation. To enhance cGMP generation in podocytes, we blocked natriuretic peptide clearance using the specific NPRC ligand ANP(4-23). We then studied the effects of NPRC blockade in both cultured podocytes and in a mouse transgenic (TG) model of focal segmental glomerulosclerosis (FSGS) created in our laboratory. In this model, a single dose of the podocyte toxin puromycin aminonucleoside (PAN) causes robust albuminuria in TG mice, but only mild disease in non-TG animals. We found that natriuretic peptides protected cultured podocytes from PAN-induced apoptosis, and that ANP(4-23) enhanced natriuretic peptide-induced cGMP generation in vivo. PAN-induced heavy proteinuria in vehicle-treated TG mice, and this increase in albuminuria was reduced by treatment with ANP(4-23). Treatment with ANP(4-23) also reduced the number of mice with glomerular injury and enhanced urinary cGMP excretion, but these differences were not statistically significant. Systolic BP was similar in vehicle and ANP(4-23)-treated mice. These data suggest that: 1. Pharmacologic blockade of NPRC may be useful for treating glomerular diseases such as FSGS, and 2. Treatment outcomes might be improved by optimizing NPRC blockade to inhibit natriuretic peptide clearance more effectively.
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Affiliation(s)
- Liming Wang
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
| | - Yuping Tang
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
| | - Anne F. Buckley
- Department of PathologyDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Robert F. Spurney
- Division of NephrologyDepartment of MedicineDuke University and Durham VA Medical CentersDurhamNorth CarolinaUSA
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Audzeyenka I, Rogacka D, Rachubik P, Typiak M, Rychłowski M, Angielski S, Piwkowska A. The PKGIα-Rac1 pathway is a novel regulator of insulin-dependent glucose uptake in cultured rat podocytes. J Cell Physiol 2021; 236:4655-4668. [PMID: 33244808 DOI: 10.1002/jcp.30188] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 11/09/2022]
Abstract
Insulin plays a major role in regulating glucose homeostasis in podocytes. Protein kinase G type Iα (PKGIα) plays an important role in regulating glucose uptake in these cells. Rac1 signaling plays an essential role in the reorganization of the actin cytoskeleton and is also essential for insulin-stimulated glucose transport. The experiments were conducted using primary rat podocytes. We performed western blot analysis, evaluated small GTPases activity assays, measured radioactive glucose uptake, and performed immunofluorescence imaging to analyze the role of PKGIα-Rac1 signaling in regulating podocyte function. We also utilized a small-interfering RNA-mediated approach to determine the role of PKGIα and Rac1 in regulating glucose uptake in podocytes. The present study investigated the influence of the PKGI pathway on the insulin-dependent regulation of activity and cellular localization of small guanosine triphosphatases in podocytes. We found that the PKGIα-dependent activation of Rac1 signaling induced activation of the PAK/cofilin pathway and increased insulin-mediated glucose uptake in podocytes. The downregulation of PKGIα or Rac1 expression abolished this effect. Rac1 silencing prevented actin remodeling and GLUT4 translocation close to the cell membrane. These data provide evidence that PKGIα-dependent activation of the Rac1 signaling pathways is a novel regulator of insulin-mediated glucose uptake in cultured rat podocytes.
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Affiliation(s)
- Irena Audzeyenka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
| | - Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
| | - Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Marlena Typiak
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Michał Rychłowski
- Laboratory of Virus Molecular Biology, University of Gdańsk, Intercollegiate Faculty of Biotechnology, Medical University of Gdańsk, , Gdańsk, Poland
| | - Stefan Angielski
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Gdańsk, Poland
- Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdańsk, Gdańsk, Poland
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Prickett TCR, Lunt H, Warwick J, Heenan HF, Espiner EA. Urinary Amino-Terminal Pro–C-Type Natriuretic Peptide: A Novel Marker of Chronic Kidney Disease in Diabetes. Clin Chem 2019; 65:1248-1257. [DOI: 10.1373/clinchem.2019.306910] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022]
Abstract
Abstract
BACKGROUND
Chronic renal inflammation and fibrosis are common sequelae in diabetes mellitus (DM) and are major causes of premature mortality. Although upregulation of NPPC expression occurs in response to renal inflammation in experimental animals, nothing is known of the molecular forms of C-type natriuretic peptide (CNP) products in urine of people with DM or links with renal function.
METHODS
ProCNP products in urine were characterized with HPLC and a range of antisera directed to specific epitopes of amino-terminal proCNP (NTproCNP). The 5-kDa intact peptide was quantified in spot urine samples from healthy adults and 202 participants with DM selected to provide a broad range of renal function.
RESULTS
The predominant products of proCNP in urine were consistent with the 2-kDa fragment (proCNP 3–20) and a smaller peak of intact (5-kDa) fragment (proCNP 1–50, NTproCNP). No peaks consistent with bioactive forms (proCNP 82–103, 50–103) were identified. The urine NTproCNP to creatinine ratio (NCR) was more reproducible than the albumin to creatinine ratio (ACR) and strongly associated with the presence of chronic kidney disease. In models predicting independence, among 10 variables associated with renal function in DM, including plasma NTproCNP, only 3 (sex, ACR, and plasma creatinine) contributed to NCR.
CONCLUSIONS
Characterization of the products of proCNP in urine confirmed the presence of NTproCNP. In spot random urine from study participants with DM, NCR is inversely associated with estimated glomerular filtration rate. In contrast to ACR, NCR reflects nonvascular factors that likely include renal inflammation and fibrosis.
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Affiliation(s)
| | - Helen Lunt
- Department of Medicine, University of Otago, Christchurch, New Zealand
- Diabetes Outpatients, Canterbury District Health Board, Christchurch, New Zealand
| | - Julie Warwick
- Diabetes Outpatients, Canterbury District Health Board, Christchurch, New Zealand
| | - Helen F Heenan
- Diabetes Outpatients, Canterbury District Health Board, Christchurch, New Zealand
| | - Eric A Espiner
- Department of Medicine, University of Otago, Christchurch, New Zealand
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Piwkowska A. Role of Protein Kinase G and Reactive Oxygen Species in the Regulation of Podocyte Function in Health and Disease. J Cell Physiol 2016; 232:691-697. [PMID: 27662602 DOI: 10.1002/jcp.25613] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/22/2016] [Indexed: 11/09/2022]
Abstract
Podocytes and their foot processes form an important cellular layer of the glomerular barrier involved in the regulation of glomerular permeability. Disturbing the function of podocytes plays a central role in the development of proteinuria in diabetic nephropathy. Retraction of the podocyte foot processes that form slit diaphragms is a common feature of proteinuria; although, the correlation between these events in not well understood. Notably, it is unclear whether podocyte foot processes are able to regulate slit diaphragm permeability and glomerular ultrafiltration. The occurrence of reactive oxygen species generation, insulin resistance, and hyperglycemia characterizes early stages of type 2 diabetes. Protein kinase G type I alpha (PKGIα) is an intracellular target for vasorelaxant factors. It is activated in both cGMP-dependent and cGMP-independent manners. Recently, we demonstrated a relationship between oxidative stress, PKGIα activation, actin reorganization, and changes in the permeability of the filtration barrier. This review discusses how redox imbalance affects both the activity of PKGIα and PKGI-dependent signaling pathways in podocytes. J. Cell. Physiol. 232: 691-697, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Agnieszka Piwkowska
- Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
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Dexamethasone-dependent modulation of cyclic GMP synthesis in podocytes. Mol Cell Biochem 2015; 409:243-53. [PMID: 26272337 PMCID: PMC4589550 DOI: 10.1007/s11010-015-2528-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 08/06/2015] [Indexed: 12/28/2022]
Abstract
Podocytes may be direct target for glucocorticoid therapy in glomerular proteinuric disease. Permeability of podocytes largely depends on their capacity to migrate which involves the contractile apparatus in their foot processes. In this study, we examined the effect of synthetic glucocorticoid dexamethasone (DEX) on the ability of podocytes to produce cyclic guanosine monophosphate (cGMP) in the presence of vasoactive factors, atrial natriuretic peptide (ANP), nitric oxide (NO), and angiotensin II (Ang II). We investigated also the effects of cGMP and DEX on podocyte motility. Primary rat podocytes and immortalized mouse podocytes were pretreated with 1 µM DEX for 4 or 24 h. Glomerular hypertension was mimicked by subjecting the cells to mechanical stress. Total and subcellular cGMP levels were determined in podocytes incubated with 0.1 µM ANP, 1 µM S-nitroso-N-acetyl penicillamine (SNAP), and 1 µM Ang II. Cell motility was estimated by a wound-healing assay. The ANP-dependent production of cGMP increased after 4 h exposition to DEX, but was attenuated after 24 h. Adversely, a 24-h pretreatment with DEX augmented the NO-dependent cGMP synthesis. Ang II suppressed the ANP-dependent cGMP production and the effect was enhanced by DEX in mechanical stress conditions. Mechanical stress reduced total cGMP production in the presence of all stimulators, whereas extracellular to total cGMP ratio increased. 8-Br cGMP enhanced podocyte migration which was accompanied by F-actin disassembly. In the presence of DEX these effects were prevented. We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX. This mechanism may account for the antiproteinuric effect of glucocorticoids.
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Kimura T, Nojiri T, Hosoda H, Ishikane S, Shintani Y, Inoue M, Miyazato M, Okumura M, Kangawa K. Protective effects of C-type natriuretic peptide on cisplatin-induced nephrotoxicity in mice. Cancer Chemother Pharmacol 2015; 75:1057-63. [PMID: 25814217 DOI: 10.1007/s00280-015-2734-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/23/2015] [Indexed: 12/28/2022]
Abstract
PURPOSE Cisplatin is a highly effective chemotherapeutic agent used to treat various malignancies, but its utility is compromised by its nephrotoxicity. C-type natriuretic peptide (CNP), a member of the natriuretic peptide family, exhibits anti-inflammatory effects by activating its specific receptor, guanylyl cyclase (GC)-B. CNP and GC-B receptor are known to be expressed in both the vascular endothelium and the kidney. The objective of this study was to investigate the renoprotective effects of CNP in a mouse model of cisplatin-induced nephrotoxicity. METHODS C57BL/6 mice were divided into three groups: normal control mice; cisplatin (20 mg/kg, intraperitoneal) mice treated with vehicle; and cisplatin mice treated with CNP (2.5 µg/kg/min, subcutaneous). At 72 h after cisplatin injection, urine, blood and kidney samples were collected. Urine and blood samples were examined biochemically. Histological findings and gene expression in kidney tissue were evaluated. RESULTS CNP reduced histological renal tubular damage and apoptosis induced by cisplatin and suppressed plasma blood urea nitrogen and creatinine levels, which were elevated by cisplatin administration. CNP treatment decreased the expression of kidney injury molecule-1 and monocyte chemoattractant protein-1, which were elevated in the kidney by cisplatin administration. CNP treatment attenuated the decrease in GC-B expression in cisplatin-induced kidney injury. CONCLUSIONS The present study is the first to show that CNP inhibits nephrotoxicity and kidney cell damage induced by cisplatin. The mechanism of action may involve down-regulation of inflammatory cytokine expression in cisplatin-induced kidney injury and attenuation of apoptosis in renal tubular cells.
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Affiliation(s)
- Toru Kimura
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, 5-7-1, Fujishirodai, Suita-City, Osaka, 565-8565, Japan,
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Yasumoto M, Tsuda A, Ishimura E, Uedono H, Ohno Y, Ichii M, Ochi A, Nakatani S, Mori K, Uchida J, Emoto M, Nakatani T, Inaba M. Significant association between glycemic status and increased estimated postglomerular resistance in nondiabetic subjects - study of inulin and para-aminohippuric acid clearance in humans. Physiol Rep 2015; 3:3/3/e12321. [PMID: 25742958 PMCID: PMC4393156 DOI: 10.14814/phy2.12321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We investigated whether glomerular hemodynamic parameters in nondiabetic subjects, including healthy subjects, are associated with glycemic status indices, by simultaneous measurement of inulin (Cin) and para-aminohippuric acid (CPHA) clearance. Twenty-six subjects (age 49.5 ± 13.3 years; 13 men and 13 women; 14 healthy subjects and 12 subjects with mild proteinuria) were enrolled. Cin and CPAH were measured simultaneously. All 26 subjects were nondiabetics. Estimated preglomerular resistance, estimated postglomerular resistance, and estimated glomerular hydrostatic pressure (Pglo) were calculated according to Gomez’ formula. Pglo correlated significantly and positively with hemoglobin A1c (HbA1c) in both healthy subjects (r = 0.532, P = 0.0498) and subjects with mild proteinuria (r = 0.681, P = 0.015). While there was no significant correlation between estimated preglomerular resistance and HbA1c, estimated postglomerular resistance correlated significantly and positively with HbA1c both in healthy subjects (r = 0.643, P = 0.013) and subjects with mild proteinuria (r = 0.589, P = 0.044). Glomerular filtration fraction, estimated Pglo and estimated postglomerular resistance in total subjects were associated significantly with HbA1c after adjustment for age, gender, and body mass index. These results demonstrate that, even in nondiabetic subjects, glycemic status is associated with estimated postglomerular resistance, but not estimated preglomerular resistance. It is suggested that increased estimated postglomerular resistance associated with higher HbA1c levels, even within the normal range, causes increased estimated Pglo, leading to increased FF. Thus, hemodynamic abnormalities associated with higher HbA1c levels may be related to glomerular hypertension, even in nondiabetic subjects.
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Affiliation(s)
- Mari Yasumoto
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Akihiro Tsuda
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Eiji Ishimura
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Hideki Uedono
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Yoshiteru Ohno
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Mitsuru Ichii
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Akinobu Ochi
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Shinya Nakatani
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Katsuhito Mori
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Junji Uchida
- Department of Urology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Masanori Emoto
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Tatsuya Nakatani
- Department of Urology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Masaaki Inaba
- Department of Nephrology, Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
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Jin X, Zhang Y, Li X, Zhang J, Xu D. C-type natriuretic peptide ameliorates ischemia/reperfusion-induced acute kidney injury by inhibiting apoptosis and oxidative stress in rats. Life Sci 2014; 117:40-5. [PMID: 25283078 DOI: 10.1016/j.lfs.2014.09.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/30/2014] [Accepted: 09/20/2014] [Indexed: 10/24/2022]
Abstract
AIMS Although atrial natriuretic peptide has been shown to attenuate ischemia-reperfusion (IR)-induced kidney injury, the effect of natriuretic peptide receptor (NPR)-B activation on IR-induced acute kidney injury is not well documented. The purpose of the present study was to identify the effect of C-type natriuretic peptide (CNP), a selective activator of NPR-B, on the IR-induced acute kidney injury and its mechanisms involved. MAIN METHODS Unilaterally nephrectomized rats were insulted by IR in their remnant kidney, and they were randomly divided into three groups: sham, vehicle+IR, and CNP+IR groups. CNP (0.2μg/kg/min) was administered intravenously at the start of a 45-min renal ischemia for 2h. Rats were then killed 24h after I/R, and the blood and tissue samples were collected to assess renal function, histology, TUNEL assay, and Western blot analysis of kidney Bax and Bcl-2 expressions. KEY FINDINGS The levels of blood urea nitrogen and serum creatinine were significantly increased in rats after IR compared with vehicle-treated rats. IR elevated apoptosis, Bcl-2/Bax ratio, TUNEL positivity, oxidative stress parameters, malondialdehyde concentration, and superoxide dismutase activity. IR also induced epithelial desquamation of the proximal tubules and glomerular shrinkage. CNP significantly attenuated the IR-induced increase in BUN and serum creatinine. Furthermore, CNP restored the suppressed renal cyclic guanosine 3' 5'-monophosphate levels caused by IR insult. SIGNIFICANCE Study findings suggest that CNP could ameliorate IR-induced acute kidney injury through inhibition of apoptotic and oxidative stress pathways, possibly through NPR-B-cGMP signaling.
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Affiliation(s)
- Xiunan Jin
- Department of Urology, Affiliated Hospital of Yanbian University, Yanji (133000), Jilin Province, China
| | - Youchen Zhang
- Department of Anatomy, Medical College of Yanbian University, Yanji (133000), Jilin Province, China
| | - Xiangdan Li
- Department of Anatomy, Medical College of Yanbian University, Yanji (133000), Jilin Province, China
| | - Jun Zhang
- Department of Anatomy, Medical College of Yanbian University, Yanji (133000), Jilin Province, China
| | - Dongyuan Xu
- Department of Anatomy, Medical College of Yanbian University, Yanji (133000), Jilin Province, China.
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Maezawa Y, Takemoto M, Yokote K. Cell biology of diabetic nephropathy: Roles of endothelial cells, tubulointerstitial cells and podocytes. J Diabetes Investig 2014; 6:3-15. [PMID: 25621126 PMCID: PMC4296695 DOI: 10.1111/jdi.12255] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/15/2014] [Indexed: 02/06/2023] Open
Abstract
Diabetic nephropathy is the major cause of end-stage renal failure throughout the world in both developed and developing countries. Diabetes affects all cell types of the kidney, including endothelial cells, tubulointerstitial cells, podocytes and mesangial cells. During the past decade, the importance of podocyte injury in the formation and progression of diabetic nephropathy has been established and emphasized. However, recent findings provide additional perspectives on pathogenesis of diabetic nephropathy. Glomerular endothelial damage is already present in the normoalbuminuric stage of the disease when podocyte injury starts. Genetic targeting of mice that cause endothelial injury leads to accelerated diabetic nephropathy. Tubulointerstitial damage, previously considered to be a secondary effect of glomerular protein leakage, was shown to have a primary significance in the progression of diabetic nephropathy. Emerging evidence suggests that the glomerular filtration barrier and tubulointerstitial compartment is a composite, dynamic entity where any injury of one cell type spreads to other cell types, and leads to the dysfunction of the whole apparatus. Accumulation of novel knowledge would provide a better understanding of the pathogenesis of diabetic nephropathy, and might lead to a development of a new therapeutic strategy for the disease.
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Affiliation(s)
- Yoshiro Maezawa
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine Chiba, Japan ; Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital Chiba, Japan
| | - Minoru Takemoto
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine Chiba, Japan ; Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital Chiba, Japan
| | - Koutaro Yokote
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine Chiba, Japan ; Division of Diabetes, Metabolism and Endocrinology, Chiba University Hospital Chiba, Japan
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Tsuda A, Ishimura E, Ohno Y, Ichii M, Nakatani S, Mori K, Fukumoto S, Emoto M, Inaba M. Significant association of poor glycemic control with increased resistance in efferent arterioles--study of inulin and para-aminohippuric acid clearance in humans. Diabetes Res Clin Pract 2014; 104:234-40. [PMID: 24598266 DOI: 10.1016/j.diabres.2014.01.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 11/14/2013] [Accepted: 01/28/2014] [Indexed: 02/08/2023]
Abstract
AIMS To examine whether glomerular hemodynamic parameters in humans are associated with glycemic control indices, by simultaneously measuring clearance of inulin (Cin) and para-aminohippuric acid (CPHA). METHODS Thirty-one subjects (age 55.4±14.7 years; 15 men and 16 women; 21 diabetics and 10 non-diabetics) were enrolled. Cin and CPAH were measured simultaneously. Afferent arteriolar resistance (Ra), efferent arteriolar resistance (Re), glomerular hydrostatic pressure (Pglo) and glomerular filtration fraction (FF) were calculated according to Gomez' formula. RESULTS FF correlated significantly and positively with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c) and glycated albumin (GA) (r=0.396, p=0.0303; r=0.587, p=0.0007; r=0.525, p=0.0070, respectively). Pglo correlated significantly and positively with FPG, HbA1c and GA (r=0.572, p=0.0008; r=0.535, p=0.0019; r=0.540, p=0.0053, respectively). Although there was no significant correlation between Ra and glycemic control indices, Re correlated significantly and positively with HbA1c and GA (r=0.499, p=0.0043; r=0.592, p=0.0018, respectively). FF, Pglo and Re were associated significantly with HbA1c and GA after adjustment for age. CONCLUSIONS These results demonstrate, in humans, that poor glycemic control is associated with increased Re, but not Ra. It is suggested that increased Re causes increased Pglo, leading to increased FF. Thus, hemodynamic abnormalities with poor glycemic control may be related to glomerular hypertension in humans.
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Affiliation(s)
- A Tsuda
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - E Ishimura
- Department of Nephrology, Osaka City University, Graduate School of Medicine, Osaka, Japan.
| | - Y Ohno
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - M Ichii
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - S Nakatani
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - K Mori
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - S Fukumoto
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - M Emoto
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
| | - M Inaba
- Department of Endocrinology, Metabolism and Molecular Medicine, Japan
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Peake N, Su N, Ramachandran M, Achan P, Salter DM, Bader DL, Moyes AJ, Hobbs AJ, Chowdhury TT. Natriuretic peptide receptors regulate cytoprotective effects in a human ex vivo 3D/bioreactor model. Arthritis Res Ther 2013; 15:R76. [PMID: 23883591 PMCID: PMC3978875 DOI: 10.1186/ar4253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 07/24/2013] [Indexed: 01/24/2023] Open
Abstract
INTRODUCTION The present study examined the effect of C-type natriuretic peptide (CNP) and biomechanical signals on anabolic and catabolic activities in chondrocyte/agarose constructs. METHODS Natriuretic peptide (Npr) 2 and 3 expression were compared in non-diseased (grade 0/1) and diseased (grade IV) human cartilage by immunofluoresence microscopy and western blotting. In separate experiments, constructs were cultured under free-swelling conditions or subjected to dynamic compression with CNP, interleukin-1β (IL-1β), the Npr2 antagonist P19 or the Npr3 agonist cANF⁴⁻²³. Nitric oxide (NO) production, prostaglandin E₂ (PGE₂) release, glycosaminoglycan (GAG) synthesis and CNP concentration were quantified using biochemical assays. Gene expression of Npr2, Npr3, CNP, aggrecan and collagen type II were assessed by real-time qPCR. Two-way ANOVA and a post hoc Bonferroni-corrected t-test were used to analyse the data. RESULTS The present study demonstrates increased expression of natriuretic peptide receptors in diseased or older cartilage (age 70) when compared to non-diseased tissue (age 60) which showed minimal expression. There was strong parallelism in the actions of CNP on cGMP induction resulting in enhanced GAG synthesis and reduction of NO and PGE₂ release induced by IL-1β. Inhibition of Npr2 with P19 maintained catabolic activities whilst specific agonism of Npr3 with cANF⁴⁻²³ had the opposite effect and reduced NO and PGE₂ release. Co-stimulation with CNP and dynamic compression enhanced anabolic activities and inhibited catabolic effects induced by IL-1β. The presence of CNP and the Npr2 antagonist abolished the anabolic response to mechanical loading and prevented loading-induced inhibition of NO and PGE₂ release. In contrast, the presence of the Npr3 agonist had the opposite effect and increased GAG synthesis and cGMP levels in response to mechanical loading and reduced NO and PGE₂ release comparable to control samples. In addition, CNP concentration and natriuretic peptide receptor expression were increased with dynamic compression. CONCLUSIONS Mechanical loading mediates endogenous CNP release leading to increased natriuretic peptide signalling. The loading-induced CNP/Npr2/cGMP signalling route mediates anabolic events and prevents catabolic activities induced by IL-1β. The CNP pathway therefore represents a potentially chondroprotective intervention for patients with OA, particularly when combined with physiotherapeutic approaches to stimulate biomechanical signals.
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Regulation of C-type natriuretic peptides and natriuretic peptide receptor-B expression in diabetic rats renal treated by Tongluo Recipe (通络方). Chin J Integr Med 2013; 19:524-31. [DOI: 10.1007/s11655-013-1507-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Indexed: 11/27/2022]
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13
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Schordan S, Grisk O, Schordan E, Miehe B, Rumpel E, Endlich K, Giebel J, Endlich N. OPN deficiency results in severe glomerulosclerosis in uninephrectomized mice. Am J Physiol Renal Physiol 2013; 304:F1458-70. [PMID: 23552865 DOI: 10.1152/ajprenal.00615.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Osteopontin (OPN) expression has been reported to be elevated in experimental models of renal injury such as arterial hypertension or diabetic nephropathy finally leading to focal segmental glomerulosclerosis (FSGS). FSGS is characterized by glomerular matrix deposition and loss or damage of podocytes that represent the main constituents of the glomerular filtration barrier. To evaluate the role of OPN in the kidney we investigated WT and OPN knockout mice (OPN-/-) without treatment, after uninephrectomy (UNX), as well as after UNX and desoxycorticosterone acetate (DOCA)-salt treatment with respect to urine parameters, glomerular morphology, and expression of podocyte markers. OPN-/- mice showed normal urine parameters while a thickening of the glomerular basement membrane was evident. Intriguingly, following UNX, OPN-/- mice exhibited prominent FSGS, proteinuria, and glomerular matrix deposition. Electron microscopy revealed bulgings of the glomerular basement membrane and occasionally an effacement of podocytes. After UNX and DOCA-salt treatment, severe glomerular lesions as well as proteinuria and albuminuria were seen in WT and OPN-/- mice. Moreover, we found a reduction of specific markers such as Wilm's tumor-1, podocin, and synaptopodin in both experimental groups indicating a loss of podocytes. Podocyte damage was accompanied by increased number of Ki-67-positive cells in the parietal epithelium of Bowman's capsule. We conclude that OPN plays a crucial role in adaptation of podocytes following renal ablation and is renoprotective when glomerular mechanical load is increased.
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Affiliation(s)
- Sandra Schordan
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
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14
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Abstract
Glomerular hypertension (ie, increased glomerular capillary pressure), has been shown to cause podocyte damage progressing to glomerulosclerosis in animal models. Increased glomerular capillary pressure results in an increase in wall tension that acts primarily as circumferential tensile stress on the capillary wall. The elastic properties of the glomerular basement membrane (GBM) and the elastic as well as contractile properties of the cytoskeleton of the endothelium and of podocyte foot processes resist circumferential tensile stress. Whether the contractile forces generated by podocytes are able to equal circumferential tensile stress to effectively counteract wall tension is an open question. Mechanical stress is transmitted from the GBM to the actin cytoskeleton of podocyte foot processes via cell-matrix contacts that contain mainly integrin α3β1 and a variety of linker, scaffolding, and signaling proteins, which are not well characterized in podocytes. We know from in vitro studies that podocytes are sensitive to stretch, however, the crucial mechanosensor in podocytes remains unclear. On the other hand, in vitro studies have shown that in stretched podocytes specific signaling cascades are activated, the synthesis and secretion of various hormones and their receptors are increased, cell-cycle arrest is reinforced, cell adhesion is altered through secretion of matricellular proteins and changes in integrin expression, and the actin cytoskeleton is reorganized in a way that stress fibers are lost. In summary, current evidence suggests that in glomerular hypertension podocytes primarily aim to maintain the delicate architecture of interdigitating foot processes in the face of an expanding GBM area.
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Affiliation(s)
- Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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15
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Robinson JW, Lou X, Potter LR. The indolocarbazole, Gö6976, inhibits guanylyl cyclase-A and -B. Br J Pharmacol 2012; 164:499-506. [PMID: 21366551 DOI: 10.1111/j.1476-5381.2011.01291.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND AND PURPOSE Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) decrease vascular volume and pressure by activating guanylyl cyclase-A (GC-A). C-type natriuretic peptide (CNP) activation of guanylyl cyclase-B (GC-B) stimulates long bone growth. This study investigated the effects of the indolocarbazole, Gö6976, on the guanylyl cyclase activity of GC-A and GC-B as a first step towards developing small molecule regulators of these enzymes. EXPERIMENTAL APPROACH Whole cell cGMP concentrations or ³²P-cGMP accumulation in membrane preparations measured the effects of indolocarbazoles on the enzymatic activity GC-A and GC-B from transfected 293T or endogenously expressing 3T3-L1 cells. KEY RESULTS Gö6976 blocked cellular CNP-dependent cGMP elevations in 293T-GC-B cells. The t(½) for Gö6976 inhibition was 7 s and IC₅₀ was 380 nM. Gö6976 increased the EC₅₀ for CNP 4.5-fold, but increasing the CNP concentration did not overcome the inhibition. Half of the inhibition was lost 1 h after removal of Gö6976 from the medium. Cellular exposure to Gö6976 reduced basal and natriuretic peptide-dependent, but not detergent-dependent, GC-A and GC-B activity. Inhibition was also observed when Gö6976 was added directly to the cyclase assay. A constitutively phosphorylated form of GC-B was similarly inhibited. CONCLUSIONS AND IMPLICATIONS These data demonstrate that Gö6976 potently, rapidly and reversibly inhibited GC-A and GC-B via a process that did not require intact cells, known phosphorylation sites or inactivation of all catalytic sites. This is the first report of an intracellular inhibitor of a transmembrane guanylyl cyclase and the first report of a non-kinase target for Gö6976.
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Affiliation(s)
- Jerid W Robinson
- Department of Pharmacology, University of Minnesota-Twin Cities, Minneapolis, MN, USA
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16
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Sangaralingham SJ, Heublein DM, Grande JP, Cataliotti A, Rule AD, McKie PM, Martin FL, Burnett JC. Urinary C-type natriuretic peptide excretion: a potential novel biomarker for renal fibrosis during aging. Am J Physiol Renal Physiol 2011; 301:F943-52. [PMID: 21865266 DOI: 10.1152/ajprenal.00170.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Renal aging is characterized by structural changes in the kidney including fibrosis, which contributes to the increased risk of kidney and cardiac failure in the elderly. Studies involving healthy kidney donors demonstrated subclinical age-related nephropathy on renal biopsy that was not detected by standard diagnostic tests. Thus there is a high-priority need for novel noninvasive biomarkers to detect the presence of preclinical age-associated renal structural and functional changes. C-type natriuretic peptide (CNP) possesses renoprotective properties and is present in the kidney; however, its modulation during aging remains undefined. We assessed circulating and urinary CNP in a Fischer rat model of experimental aging and also determined renal structural and functional adaptations to the aging process. Histological and electron microscopic analysis demonstrated significant renal fibrosis, glomerular basement membrane thickening, and mesangial matrix expansion with aging. While plasma CNP levels progressively declined with aging, urinary CNP excretion increased, along with the ratio of urinary to plasma CNP, which preceded significant elevations in proteinuria and blood pressure. Also, CNP immunoreactivity was increased in the distal and proximal tubules in both the aging rat and aging human kidneys. Our findings provide evidence that urinary CNP and its ratio to plasma CNP may represent a novel biomarker for early age-mediated renal structural alterations, particularly fibrosis. Thus urinary CNP could potentially aid in identifying subjects with preclinical structural changes before the onset of symptoms and disease, allowing for the initiation of strategies designed to prevent the progression of chronic kidney disease particularly in the aging population.
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Affiliation(s)
- S Jeson Sangaralingham
- Cardiorenal Research Laboratory, Div. of Cardiovascular Diseases, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.
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17
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Schordan S, Schordan E, Endlich K, Endlich N. AlphaV-integrins mediate the mechanoprotective action of osteopontin in podocytes. Am J Physiol Renal Physiol 2010; 300:F119-32. [PMID: 21048023 DOI: 10.1152/ajprenal.00143.2010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Increased mechanical load in podocytes due to glomerular hypertension is one of the important factors leading to podocyte damage and chronic kidney disease. In previous studies, we have shown that mechanical stretch increases osteopontin (OPN) expression in podocytes and that exogenous OPN is mechanoprotective via facilitating cytoskeletal reorganization of podocytes. In the present study, we asked whether the mechanoprotective effect of OPN in podocytes is mediated through specific integrins and whether endogenous OPN of podocytes is required for mechanoprotection. Conditionally immortalized mouse podocytes and primary podocytes (PP) from OPN-/- and OPN+/+ mice were used. Cyclic biaxial mechanical stretch (0.5 Hz, 7% linear strain) was applied for up to 3 days. Stretch-induced cell loss was ∼30% higher in OPN-/- PP compared with OPN+/+ PP. Increased cell loss of OPN-/- PP was rescued by OPN coating. Analysis of integrin expression by RT-PCR, application of RGD and SLAYGLR peptides and anti-integrin antibodies, small-interfering RNA knockdown of integrins, and application of kinase inhibitors identified αV-integrins (αVβ1, αVβ3, and αVβ5) to mediate the mechano-protective effect of OPN in podocytes involving focal adhesion kinase, Src, phosphatidylinositol 3-kinase, and mitogen-activated protein kinase. Our results demonstrate that endogenous OPN of podocytes plays a nonredundant role in podocyte adaptation to mechanical stretch, and that OPN signaling via α(V)-integrins may represent a relevant therapeutical target in podocytes.
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Affiliation(s)
- Sandra Schordan
- Department of Anatomy and Cell Biology, University of Greifswald, Greifswald, Germany
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18
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CD-NP: an innovative designer natriuretic peptide activator of particulate guanylyl cyclase receptors for cardiorenal disease. Curr Heart Fail Rep 2010; 7:93-9. [PMID: 20582736 DOI: 10.1007/s11897-010-0016-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The natriuretic peptide (NP) family consists of structurally similar, although physiologically distinct, peptides that play an important role in cardiorenal homeostasis. CD-NP is a novel chimeric natriuretic peptide developed by the Mayo Clinic, in which the 15-amino acid COOH-terminus of dendroaspis NP is fused to C-type NP. CD-NP is a dual activator of NP receptors A and B, and therefore, possesses the strong antiproliferative and antifibrotic properties of C-type NP with the potent natriuretic, diuretic, and aldosterone-inhibiting properties of dendroaspis NP. CD-NP has favorable cardiorenal properties when compared to recombinant B-type NP (nesiritide), including preservation of glomerular filtration rate with minimal blood pressure-lowering effects. Thus, CD-NP has emerged as an appealing novel therapeutic strategy for heart failure. The endogenous NP system, the development rationale for CD-NP, as well as in vitro, animal, and human studies and future directions will be reviewed.
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Shpakov AO, Derkach KV, Chistyakova OV, Pertseva MN. Changes in the functional activity of membrane-bound guanylate cyclase forms in tissues of diabetic rats. DOKL BIOCHEM BIOPHYS 2010; 433:219-22. [PMID: 20714861 DOI: 10.1134/s1607672910040198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Indexed: 11/23/2022]
Affiliation(s)
- A O Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
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20
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Lewko B, Stepinski J. Hyperglycemia and mechanical stress: Targeting the renal podocyte. J Cell Physiol 2009; 221:288-95. [DOI: 10.1002/jcp.21856] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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21
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Aldosterone and glomerular podocyte injury. Clin Exp Nephrol 2008; 12:233-242. [DOI: 10.1007/s10157-008-0034-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 11/19/2007] [Indexed: 10/22/2022]
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22
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Makino H, Mukoyama M, Mori K, Suganami T, Kasahara M, Yahata K, Nagae T, Yokoi H, Sawai K, Ogawa Y, Suga S, Yoshimasa Y, Sugawara A, Tanaka I, Nakao K. Transgenic overexpression of brain natriuretic peptide prevents the progression of diabetic nephropathy in mice. Diabetologia 2006; 49:2514-24. [PMID: 16917760 DOI: 10.1007/s00125-006-0352-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Accepted: 05/15/2006] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Brain natriuretic peptide (BNP) is a potent vasorelaxing and natriuretic peptide that is secreted from the heart and has cardioprotective properties. We have previously generated hypotensive transgenic mice (BNP-Tg mice) that overproduce BNP in the liver, which is released into the circulation. Using this animal model, we successfully demonstrated the amelioration of renal injury after renal ablation and in proliferative glomerulonephritis. Glomerular hyperfiltration is an early haemodynamic derangement, representing one of the key mechanisms of the pathogenesis of diabetic nephropathy. Based on the suggested involvement of increased endogenous natriuretic peptides, the aim of this study was to investigate their role in the development and progression of diabetic nephropathy. MATERIALS AND METHODS We evaluated the progression of renal injury and fibrogenesis in BNP-Tg mice with diabetes induced by streptozotocin. We also investigated the effect of BNP on high glucose-induced signalling abnormalities in mesangial cells. RESULTS After induction of diabetes, control mice exhibited progressively increased urinary albumin excretion with impaired renal function, whereas these changes were significantly ameliorated in BNP-Tg mice. Notably, diabetic BNP-Tg mice revealed minimal mesangial fibrogenesis with virtually no glomerular hypertrophy. Glomerular upregulation of extracellular signal-regulated kinase, TGF-beta and extracellular matrix proteins was also significantly inhibited in diabetic BNP-Tg mice. In cultured mesangial cells, activation of the above cascade under high glucose was abrogated by the addition of BNP. CONCLUSIONS/INTERPRETATION Chronic excess of BNP prevents glomerular injury in the setting of diabetes, suggesting that renoprotective effects of natriuretic peptides may be therapeutically applicable in preventing the progression of diabetic nephropathy.
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Affiliation(s)
- H Makino
- Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan
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23
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Chalmers L, Kaskel FJ, Bamgbola O. The role of obesity and its bioclinical correlates in the progression of chronic kidney disease. Adv Chronic Kidney Dis 2006; 13:352-64. [PMID: 17045221 DOI: 10.1053/j.ackd.2006.07.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In spite of a progressive fall in the incidence of traditional risk factors of cardiovascular morbidity (cigarette smoking, high blood pressure, and hyperlipidemia), there is an upward trend in the prevalence of obesity and chronic kidney disease (CKD). Furthermore, there is a strong correlation between body mass indices and the relative risk of progression of CKD. The close biophysiological interaction between obesity and CKD is evident by a similar occurrence of comorbidities including insulin resistance, hyperlipidermia, endothelial dysfunction, and sleep disorders. Truncal obesity is a primary component of metabolic syndrome; unlike peripheral fat, the visceral adipocytes are more resistant to insulin. In addition, lipolysis results in a release of free fatty acid and TG, whereas hypertriglycedemia is potentiated by uremic activation of fatty acid synthase. Hypertriglycedemia and low HDL cholesterol increase the relative risk of progression of CKD. Furthermore, endothelial inflammation and premature atherosclerosis are promoted by hyperhomocysteinemia and oxidation of LDL, both of which are commonly observed in CKD and obesity. Predominance of oxidative stress in both obesity and azotemia stimulate synthesis of angiotensin II, which in turn increases TGF-B and plasminogen activator inhibitor-1, thereby propagating glomerular fibrosis. Furthermore, local synthesis of angiotensinogen by adipocytes, leptin activation of sympathetic nervous system, and hyperinsulinemia contribute to the development of hypertension in obesity and CKD. In addition, increased renal tubular expression of Na-K-ATPase and a blunted response to natiuretic hormones in obesity promote salt and water retention. Glomerular hyperfiltration from systemic volume load and hypertension results in mesangial cellular proliferation and progressive renal fibrosis. In addition, maternal nutritional deprivation increases the incidence of obesity, hypertension, and diabetes in adulthood. Reduced fetal protein synthesis contributes to oxidative glomerular injury and impairment of renal morphogenesis. Thus, kidneys are poorly equipped to handle physiologic stress that may result from the rapid body growth and programmed metabolic dysfunction later in life. Finally, in order to minimize morbidity of obesity-related kidney disease, preventive strategy must include optimal maternal health care, promotion of healthy nutrition and routine physical exercise, and early detection of CKD.
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Affiliation(s)
- Laura Chalmers
- Department of Pediatrics, Oklahoma University Health Science Center, Oklahoma City, OK 73104, USA
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24
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Friedrich C, Endlich N, Kriz W, Endlich K. Podocytes are sensitive to fluid shear stress in vitro. Am J Physiol Renal Physiol 2006; 291:F856-65. [PMID: 16684926 DOI: 10.1152/ajprenal.00196.2005] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Podocytes are exposed to mechanical forces arising from glomerular capillary pressure and filtration. It has been shown that stretch affects podocyte biology in vitro and plays a significant role in the development of glomerulosclerosis in vivo. However, whether podocytes are sensitive to fluid shear stress is completely unknown. In the present study, we therefore exposed cells of a recently generated conditionally immortalized mouse podocyte cell line to defined fluid shear stress in a flow chamber, mimicking flow of the glomerular ultrafiltrate over the surface of podocytes in Bowman's space. Shear stress above 0.25 dyne/cm(2) resulted in dramatic loss of podocytes but not of proximal tubular epithelial cells (LLC-PK(1) cells) after 20 h. At 0.015-0.25 dyne/cm(2), lamellipodia formation in podocytes was enhanced and the actin nucleation protein cortactin was redistributed to the cell margins. Shear stress further diminished stress fibers and the presence of vinculin in focal adhesions. Linear zonula occludens-1 distribution at cell-cell contacts remained unaffected at low shear stress. At 0.25 dyne/cm(2), the monolayer was broken up and remaining cell-cell contacts were reinforced by F-actin and alpha-actinin. Because the cytoskeletal changes induced by shear stress suggested the involvement of tyrosine kinases (TKs), we tested several TK inhibitors that were all without effect on podocyte number under static conditions. At 0.25 dyne/cm(2), however, the TK inhibitors genistein and AG 82 were associated with marked podocyte loss. Our data demonstrate that podocytes are highly sensitive to fluid shear stress. Shear stress induces a reorganization of the actin cytoskeleton and activates specific tyrosine kinases that are required to withstand fluid shear stress.
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Affiliation(s)
- Colin Friedrich
- Department of Anatomy and Cell Biology I, University of Heidelberg, Heidelberg, Germany
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Hino M, Nagase M, Kaname S, Shibata S, Nagase T, Oba S, Funaki M, Kobayashi N, Kawachi H, Mundel P, Fujita T. Expression and regulation of adrenomedullin in renal glomerular podocytes. Biochem Biophys Res Commun 2005; 330:178-85. [PMID: 15781248 DOI: 10.1016/j.bbrc.2005.02.142] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Indexed: 10/25/2022]
Abstract
Adrenomedullin (AM) is postulated to exert organ-protective effects. It is expressed in the renal glomeruli, but its roles in the glomerular podocytes have been poorly elucidated. In the present study, we investigated the expression and regulation of AM in recently established conditionally immortalized mouse podocyte cell line in vitro and podocyte injury model in vivo. The cultured differentiated podocytes expressed AM mRNA and secreted measurable amount of AM. AM secretion from the podocytes was increased by H(2)O(2), hypoxia, puromycin aminonucleoside (PAN), albumin overload, and TNF-alpha. Real-time RT-PCR analysis revealed that AM mRNA expression in the podocytes was enhanced by PAN and TNF-alpha, both of which were suppressed by mitochondrial antioxidants. Furthermore, AM expression was upregulated in the glomerular podocytes of PAN nephrosis rats. These results indicated that AM expression in the podocytes was upregulated by stimuli or condition relevant to podocyte injury, suggesting its potential role in podocyte pathophysiology.
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Affiliation(s)
- Masayo Hino
- Department of Nephrology and Endocrinology, University of Tokyo Graduate School of Medicine, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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