scholarly journals Nephron-specific knockout of TMEM16A leads to reduced number of glomeruli and albuminuria

2018 ◽  
Vol 315 (6) ◽  
pp. F1777-F1786 ◽  
Author(s):  
Laura K. Schenk ◽  
Bjoern Buchholz ◽  
Sebastian F. Henke ◽  
Ulf Michgehl ◽  
Christoph Daniel ◽  
...  
Keyword(s):  
Transmembrane Protein ◽  
Renal Physiology ◽  
Tubular Damage ◽  
Channel Activity ◽  
Ureteric Bud ◽  
Cellular Functions ◽  
Proximal Tubular ◽  
Corticomedullary Differentiation ◽  
Knockout Animals ◽  
Cyst Growth

TMEM16A is a transmembrane protein from a conserved family of calcium-activated proteins that is highly expressed in the kidney. TMEM16A confers calcium-activated chloride channel activity, which is of importance for various cellular functions in secretory epithelia and involved in secretion-dependent renal cyst growth. However, its specific function in renal physiology has remained elusive so far. Therefore, we generated conditional nephron-specific TMEM16A-knockout mice and found that these animals suffered from albuminuria. Kidney histology demonstrated an intact corticomedullary differentiation and absence of cysts. Electron microscopy showed a normal slit diaphragm. However, the total number of glomeruli and total nephron count was decreased in TMEM16A-knockout animals. At the same time, glomerular diameter was increased, presumably as a result of the hyperfiltration in the remaining glomeruli. TUNEL and PCNA stainings showed increased cell death and increased proliferation. Proximal tubular cilia were intact in young animals, but the number of properly ciliated cells was decreased in older, albuminuric animals. Taken together, our data suggest that TMEM16A may be involved in ureteric bud branching and proper nephron endowment. Loss of TMEM16A resulted in reduced nephron number and, subsequently, albuminuria and tubular damage.

New insights into the mechanisms involved in renal proximal tubular damage induced in vitro by ochratoxin A

2004 ◽  
Vol 18 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Alessandra Gennari ◽  
Patricia Pazos ◽  
Monica Boveri ◽  
Robert Callaghan ◽  
Juan Casado ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Tubular Damage ◽  
Proximal Tubular ◽  
Proximal Tubular Damage ◽  
Renal Proximal Tubular

scholarly journals Sodium Glucose Co-Transporter 2 Inhibitor Ameliorates Autophagic Flux Impairment on Renal Proximal Tubular Cells in Obesity Mice

2020 ◽  
Vol 21 (11) ◽  
pp. 4054
Author(s):  
Kazuhiko Fukushima ◽  
Shinji Kitamura ◽  
Kenji Tsuji ◽  
Yizhen Sang ◽  
Jun Wada
Keyword(s):  
Renal Injury ◽  
Tubular Damage ◽  
Autophagic Flux ◽  
Protective Effects ◽  
Renal Protection ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular

Obesity is supposed to cause renal injury via autophagy deficiency. Recently, sodium glucose co-transporter 2 inhibitors (SGLT2i) were reported to protect renal injury. However, the mechanisms of SGLT2i for renal protection are unclear. Here, we investigated the effect of SGLT2i for autophagy in renal proximal tubular cells (PTCs) on obesity mice. We fed C57BL/6J mice with a normal diet (ND) or high-fat and -sugar diet (HFSD) for nine weeks, then administered SGLT2i, empagliflozin, or control compound for one week. Each group contained N = 5. The urinary N-acetyl-beta-d-glucosaminidase level in the HFSD group significantly increased compared to ND group. The tubular damage was suppressed in the SGLT2i–HFSD group. In electron microscopic analysis, multi lamellar bodies that increased in autophagy deficiency were increased in PTCs in the HFSD group but significantly suppressed in the SGLT2i group. The autophagosomes of damaged mitochondria in PTCs in the HFSD group frequently appeared in the SGLT2i group. p62 accumulations in PTCs were significantly increased in HFSD group but significantly suppressed by SGLT2i. In addition, the mammalian target of rapamycin was activated in the HFSD group but significantly suppressed in SGLT2i group. These data suggest that SGLT2i has renal protective effects against obesity via improving autophagy flux impairment in PTCs on a HFSD.

scholarly journals Epithelial Na+ channel activation and processing in mice lacking SGK1

2008 ◽  
Vol 294 (6) ◽  
pp. F1298-F1305 ◽  
Author(s):  
Geza Fejes-Tóth ◽  
Gustavo Frindt ◽  
Aniko Náray-Fejes-Tóth ◽  
Lawrence G. Palmer
Keyword(s):  
Full Length ◽  
Na Channel ◽  
Channel Activity ◽  
Salt Wasting ◽  
Optimal Processing ◽  
Collecting Ducts ◽  
Cell Current ◽  
Dependent Protein ◽  
Knockout Animals ◽  
Epithelial Na Channel

Amiloride-sensitive Na+ channel activity was examined in the cortical collecting ducts of a mouse line (SGK1−/−) deficient in the serum- and glucocorticoid-dependent protein kinase SGK1. This activity was correlated with changes in renal Na handling and in the maturation of epithelial Na+ channel (ENaC) protein. Neither SGK1−/− mice nor paired SGK1+/+ animals expressed detectable channel activity, measured as amiloride-sensitive whole-cell current ( INa), under control conditions with standard chow. Administration of aldosterone (0.5 μg/h via osmotic minipump for 7 days) increased INa to a similar extent in SGK1+/+ (378 ± 61 pA/cell at −100 mV) and in SGK1−/− (350 ± 57 pA/cell) animals. However, the maturation of ENaC, assessed as the ratio of cleaved to full-length forms of γ-ENaC, was more pronounced in SGK+/+ mice. The SGK1−/− animals exhibited a salt-wasting phenotype when kept on a low-Na diet for up to 2 days, losing significantly more Na in the urine than wild-type mice. Under these conditions, INa was enhanced more in SGK1−/− (94 ± 14 pA/cell) than in SGK+/+ (23 ± 5 pA/cell) genotypes. Despite the larger currents, the ratio of cleaved to full-length γ-ENaC was lower in the knockout animals. The mice also expressed a smaller amount of Na+-Cl− cotransporter protein under Na-depleted conditions. These results indicated that SGK1 is essential for optimal processing of ENaC but is not required for activation of the channel by aldosterone.

scholarly journals Emerging concepts regarding pannexin 1 in the vasculature

2015 ◽  
Vol 43 (3) ◽  
pp. 495-501 ◽  
Author(s):  
Miranda E. Good ◽  
Daniela Begandt ◽  
Leon J. DeLalio ◽  
Alexander S. Keller ◽  
Marie Billaud ◽  
...  
Keyword(s):  
Vascular Function ◽  
Atp Release ◽  
The Body ◽  
Purinergic Signalling ◽  
Molecular Tools ◽  
Cellular Functions ◽  
Post Translational Modifications ◽  
Pannexin 1 ◽  
Knockout Animals

Pannexin channels are newly discovered ATP release channels expressed throughout the body. Pannexin 1 (Panx1) channels have become of great interest as they appear to participate in a multitude of signalling cascades, including regulation of vascular function. Although numerous Panx1 pharmacological inhibitors have been discovered, these inhibitors are not specific for Panx1 and have additional effects on other proteins. Therefore, molecular tools, such as RNA interference and knockout animals, are needed to demonstrate the role of pannexins in various cellular functions. This review focuses on the known roles of Panx1 related to purinergic signalling in the vasculature focusing on post-translational modifications and channel gating mechanisms that may participate in the regulated release of ATP.

scholarly journals Damage to proximal tubular epithelial cells in type 2 diabetes mellitus

2007 ◽  
Vol 60 (5-6) ◽  
pp. 272-276 ◽  
Author(s):  
Vlastimir Vlatkovic ◽  
Biljana Stojimirovic ◽  
Radmila Obrenovic ◽  
Spomenka Nogic
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Control Group ◽  
Tubular Damage ◽  
Gamma Glutamyl Transferase ◽  
Irreversible Damage ◽  
Proximal Tubular ◽  
Glutamyl Transferase

Introduction: Kidney damage from diabetes mellitus is called diabetic nephropathy. At the beginning it is a functional disorder, but later it results in an irreversible damage. The aim of this research was to establish damage to proximal tubular cells in patients with type 2 diabetes mellitus, and various degrees of proteinuria by determining the urinary N-acetyl-b-D-glucose-aminidase and g-glutamyl-transferase; to compare obtained results with the results in healthy examinees; to establish the correlation between these enzymes, and to investigate their sensitivity. Material and methods Patients with type 2 diabetes mellitus and creatinine clearence >80 ml/min were included in the research. Patients were divided into three groups, according to the degree of proteinuria. The first group included diabetics without microalbuminuria; the second - patients with proteinuria <300 mg/24h and microalbuminuria >20 mg/24h, and the third group included patients with proteinuria >300 mg/24h. Healthy examinees were the control group. Results: Values of the urinary N-acetyl-b-D-glucosaminidase activity were elevated before microalbuminuria was observed. The highest values were detected in the group of patients with microalbuminuria. Differences among the examined groups were statistically significant, which implies that this enzyme has a high diagnostic importance. Enzyme g-glutamyl-transferase was less sensitive in this research. The activity of this enzyme was increased only in the group of patients with proteinuria >300 mg/24h, where values increased with diabetes mellitus duration. Conclusion The increased activity of urinary N-acetyl-b-D-glucosaminidase points to early tubular damage, and can be used as a sensitive parameter in its early detection. On the other hand, gamma-glutamyl-transferase was a less sensitive damage indicator.

scholarly journals A mammalian homolog of the zebrafish transmembrane protein 2 (TMEM2) is the long-sought-after cell-surface hyaluronidase

2017 ◽  
Vol 292 (18) ◽  
pp. 7304-7313 ◽  
Author(s):  
Hayato Yamamoto ◽  
Yuki Tobisawa ◽  
Toshihiro Inubushi ◽  
Fumitoshi Irie ◽  
Chikara Ohyama ◽  
...  
Keyword(s):  
Cell Surface ◽  
Dermatan Sulfate ◽  
Transmembrane Protein ◽  
Live Cells ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Ph Optimum ◽  
Hyaluronidase Activity ◽  
A Cell ◽  
Intermediate Size

Hyaluronan (HA) is an extremely large polysaccharide (glycosaminoglycan) involved in many cellular functions. HA catabolism is thought to involve the initial cleavage of extracellular high-molecular-weight (HMW) HA into intermediate-size HA by an extracellular or cell-surface hyaluronidase, internalization of intermediate-size HA, and complete degradation into monosaccharides in lysosomes. Despite considerable research, the identity of the hyaluronidase responsible for the initial HA cleavage in the extracellular space remains elusive. HYAL1 and HYAL2 have properties more consistent with lysosomal hyaluronidases, whereas CEMIP/KIAA1199, a recently identified HA-binding molecule that has HA-degrading activity, requires the participation of the clathrin-coated pit pathway of live cells for HA degradation. Here we show that transmembrane protein 2 (TMEM2), a mammalian homolog of a protein playing a role in zebrafish endocardial cushion development, is a cell-surface hyaluronidase. Live immunostaining and surface biotinylation assays confirmed that mouse TMEM2 is expressed on the cell surface in a type II transmembrane topology. TMEM2 degraded HMW-HA into ∼5-kDa fragments but did not cleave chondroitin sulfate or dermatan sulfate, indicating its specificity to HA. The hyaluronidase activity of TMEM2 was Ca2+-dependent; the enzyme's pH optimum is around 6–7, and unlike CEMIP/KIAA1199, TMEM2 does not require the participation of live cells for its hyaluronidase activity. Moreover, TMEM2-expressing cells could eliminate HA immobilized on a glass surface in a contact-dependent manner. Together, these data suggest that TMEM2 is the long-sought-after hyaluronidase that cleaves extracellular HMW-HA into intermediate-size fragments before internalization and degradation in the lysosome.

scholarly journals Sotagliflozin, a dual SGLT1/2 inhibitor, improves cardiac outcomes in a mouse model of early heart failure without diabetes

2020 ◽  
Author(s):  
Sophia L Young ◽  
Lydia Ryan ◽  
Thomas P Mullins ◽  
Melanie Flint ◽  
Sarah E Steane ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Fibrosis ◽  
Pressure Overload ◽  
Normal Diet ◽  
Whole Body ◽  
Tubular Damage ◽  
Diabetic Mice ◽  
High Fat ◽  
Cardiac Outcomes ◽  
Proximal Tubular

AbstractAimsSelective SGLT2 inhibition reduces the risk of worsening heart failure and cardiovascular death in patients with existing heart failure, irrespective of diabetic status. We aimed to investigate the effects of dual SGLT1/2 inhibition, using sotagliflozin, on cardiac outcomes in non-diabetic and diabetic mice with cardiac pressure overload.Methods and ResultsFive-week old male C57BL/6J mice were randomized to receive a high fat diet (HFD; 60% of calories from fat) to induce diabetes or remain on normal diet (ND) for 12 weeks. Transverse aortic constriction (TAC) was then employed to induce cardiac pressure-overload (50% increase in right:left carotid pressure versus sham surgery), resulting in features representative of heart failure with preserved ejection fraction. At five weeks into the dietary protocol, mice were treated for seven weeks by oral gavage once daily with sotagliflozin (10mg/kg body weight) or vehicle (0.1% tween 80). In ND non-diabetic mice, treatment with sotagliflozin attenuated cardiac hypertrophy and histological markers of cardiac fibrosis induced by TAC. These benefits were associated with profound diuresis and glucosuria, without shifts toward whole-body fatty acid utilisation nor increased cardiac ketolysis. In HFD diabetic mice, sotagliflozin did not attenuate cardiac injury induced by TAC. HFD mice had vacuolation of proximal tubular cells, associated with less profound diuresis and glucosuria, which may have compromised drug action and subsequent cardio-protection.ConclusionWe demonstrate the utility of dual SGLT1/2 inhibition in treating heart failure risk factors in the non-diabetic state. Its efficacy in high fat-induced diabetes with proximal tubular damage requires further study.

Regenerative and Proinflammatory Effects of Thrombin on Human Proximal Tubular Cells

2000 ◽  
Vol 11 (6) ◽  
pp. 1016-1025 ◽  
Author(s):  
GIUSEPPE GRANDALIANO ◽  
RAFFAELLA MONNO ◽  
ELENA RANIERI ◽  
LORETO GESUALDO ◽  
FRANCESCO P. SCHENA ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Dna Synthesis ◽  
Coagulation Cascade ◽  
Tubular Damage ◽  
Thymidine Uptake ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Gene And Protein Expression ◽  
Proximal Tubular

Abstract. Interstitial fibrin deposition is a common histologic feature of tubulointerstitial diseases, which suggests that the coagulation system is activated. Thrombin, generated during the activation of the coagulation cascade, is a powerful activating factor for different cell types. Although proximal tubular cells are potential targets for this coagulation factor, no information is available on the effect of thrombin on these cells. Thus, the expression of protease-activated receptor-1 (PAR-1), the main thrombin receptor, was investigated in human proximal tubular cells (hPTC)in vivoandin vitro. A diffuse expression of PAR-1 was observed by immunohistochemistry along the basolateral membrane of PTC in normal human kidney. This observation was confirmedin vitroin cultured hPTC. Because tubular damage and monocyte infiltration are two hallmarks of tubulointerstitial injury, the effect of thrombin on DNA synthesis and monocyte chemotactic peptide-1 (MCP-1) gene and protein expression was evaluated in cultured hPTC. Thrombin induced a significant and dose-dependent increase in thymidine uptake and a striking upregulation of MCP-1 mRNA expression and protein release into the supernatant. Although PAR-1 is a G protein-coupled receptor, its activation in hPTC, as in other cell systems, resulted in a transient increase in cellular levels of tyrosine-phosphorylated proteins. An increased level of tyrosine-phosphorylated c-src suggested the activation of this cytoplasmic tyrosine kinase in response to thrombin and its potential role in thrombin-induced protein-tyrosine phosphorylation. Interestingly, thrombin-induced DNA synthesis and MCP-1 gene expression were completely blocked by genistein, a specific tyrosine kinase inhibitor, but not by its inactive analogue daidzein, demonstrating a central role for tyrosine kinase activation in the thrombin effects on hPTC. Moreover, the specific src inhibitor PP1 abolished the thrombin effect on DNA synthesis. In conclusion, thrombin might represent a powerful regenerative and proinflammatory stimulus for hPTC in acute and chronic tubulointerstitial diseases.

Some Aspects of Nephrotoxicity of Paracetamol and Ketoprofen in Patients with Rheumathoid Arthritis

2016 ◽  
Vol 70 (3) ◽  
pp. 118-124
Author(s):  
Dejan Spasovski ◽  
Sonja Genadieva-Stavric ◽  
Tatjana Sotirova
Keyword(s):  
Colorimetric Method ◽  
Initial Therapy ◽  
Tubular Damage ◽  
Moderate Correlation ◽  
Time Intervals ◽  
Number Of Patients ◽  
Proximal Tubular ◽  
Proximal Tubular Damage

Abstract Introduction. To determine the effect of initial therapy with Paracetamol and Ketoprofen on glomerular and tubular integrity in rheumatoid arthritis (RA), to quantify nephrotoxicity of these two drugs by measurement of enzymuria, which correlates with the damage of tubular epithelium. Microalbuminuria is used as a marker for glomerular damage, and urine excretion of N-Acetyl-b-D-glucosaminidase (NAG) as an indicator of proximal tubular damage. Methods. Using colorimetric method for determination of NAG, and immunoturbidimetric method for microalbuminuria, samples of 70 participants were examined (35 RA patients treated with Paracetamol only, 35 RA patients treated with Ketoprofen). The follow-up was in 5 time-intervals in the course of 24 weeks. Results. There was a moderate correlation between NAG and microalbuminuria (r=0.16) in the group of patients treated with Paracetamol only, and a moderate correlation (r=0.28) in the group of patients treated with Ketoprofen. NAG enzymuria in size, by number of patients Registered, and time of appearance, was greater and appeared earlier in the Ketoprofen group compared to the Paracetamol group. Conclusions. Ketoprofen is more potent NAG inductor and provokes greater tubular enzymuria than Paracetamol. Results from our study confirm safety in use of Paracetamol and Ketoprofen in everyday clinical practice.

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