scholarly journals Podocyte Foot Process Effacement Precedes Albuminuria and Glomerular Hypertrophy in CD2-Associated Protein Deficient Mice

2021 ◽  
Vol 8 ◽  
Author(s):  
John M. Basgen ◽  
Jenny S. Wong ◽  
Justina Ray ◽  
Susanne B. Nicholas ◽  
Kirk N. Campbell
Keyword(s):  
Light And Electron Microscopy ◽  
Glomerular Hypertrophy ◽  
Mesangial Expansion ◽  
Podocyte Injury ◽  
Glomerular Volume ◽  
Urine Albumin ◽  
Foot Process Effacement ◽  
Foot Process ◽  
Grid Points ◽  
Deficient Mice

Background: Podocyte foot process effacement is a key histologic finding in proteinuric kidney disease. We previously showed that 3-week old CD2AP-deficient mice have significant proteinuria, glomerular hypertrophy and mesangial expansion. The goal of this study is to use morphometry to establish the temporal sequence of podocyte foot process effacement, glomerular volume expansion and albuminuria in Cd2ap−/− mice by measuring these parameters at the 2-week time point.Methods: Wild-type mice age 14 ± 1 days with the Cd2ap gene (WT, N = 5) and mice deficient for Cd2ap (Cd2ap KO, N = 5) were generated. Kidneys were harvested and fixed in 2.5% glutaraldehyde and processed for examination by light and electron microscopy. An average of 415.2 (range 268–716) grid points were counted for all the glomeruli, and quantification of glomerular volume from each kidney. Urine was collected the day prior to sacrifice for urine albumin-to-creatinine ratio (ACR) measurements.Results: There was no difference in albuminuria [median (range) mg/g] between WT [212.2 (177.6–388.4) mg/g] vs. Cd2ap KO mice [203.3 (164.7–910.2) mg/g], P = 0.89; or glomerular volume 68,307[10,931] vs. 66,844[13,022] μm3, p = 0.92. The volume densities of glomerular components of the podocyte, capillary lumen and mesangium were not different for the two groups, P = 0.14, 0.14 and 0.17 respectively. However, foot process width was increased in Cd2ap KO 1128[286] vs. WT [374 ± 42] nm, P = 0.02.Conclusion: Here we show that while 2-week old WT and Cd2ap KO mice have similar levels of albuminuria, glomerular and mesangial volume, Cd2ap KO mice have more extensive podocyte foot process effacement. The data suggests that podocyte injury is the initiating event leading to mesangial expansion and albuminuria in this model.

scholarly journals Early podocyte injury and elevated levels of urinary podocyte-derived extracellular vesicles in swine with metabolic syndrome: role of podocyte mitochondria

2019 ◽  
Vol 317 (1) ◽  
pp. F12-F22 ◽  
Author(s):  
Li-Hong Zhang ◽  
Xiang-Yang Zhu ◽  
Alfonso Eirin ◽  
Arash Aghajani Nargesi ◽  
John R. Woollard ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Extracellular Vesicles ◽  
Light And Electron Microscopy ◽  
Urinary Concentration ◽  
Glomerular Injury ◽  
Podocyte Injury ◽  
Early Markers ◽  
Nutrient Surplus ◽  
Glomerular Size ◽  
Foot Process

Metabolic syndrome (MetS) is associated with nutrient surplus and kidney hyperfiltration, accelerating chronic renal failure. The potential involvement of podocyte damage in early MetS remains unclear. Mitochondrial dysfunction is an important determinant of renal damage, but whether it contributes to MetS-related podocyte injury remains unknown. Domestic pigs were studied after 16 wk of diet-induced MetS, MetS treated with the mitochondria-targeted peptide elamipretide (ELAM; 0.1 mg·kg−1·day−1 sc) for the last month of diet, and lean controls ( n = 6 pigs/group). Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured using multidetector computed tomography, and podocyte and mitochondrial injury were measured by light and electron microscopy. Urinary levels of podocyte-derived extracellular vesicles (pEVs; nephrin positive/podocalyxin positive) were characterized by flow cytometry. Body weight, blood pressure, RBF, and GFR were elevated in MetS. Glomerular size and glomerular injury score were also elevated in MetS and decreased after ELAM treatment. Evidence of podocyte injury, impaired podocyte mitochondria, and foot process width were all increased in MetS but restored with ELAM. The urinary concentration of pEVs was elevated in MetS pigs and directly correlated with renal dysfunction, glomerular injury, and fibrosis and inversely correlated with glomerular nephrin expression. Additionally, pEV numbers were elevated in the urine of obese compared with lean human patients. Early MetS induces podocyte injury and mitochondrial damage, which can be blunted by mitoprotection. Urinary pEVs reflecting podocyte injury might represent early markers of MetS-related kidney disease and a novel therapeutic target.

scholarly journals Dosage-dependent role of Rac1 in podocyte injury

2016 ◽  
Vol 310 (8) ◽  
pp. F777-F784 ◽  
Author(s):  
Xiaoyang Wan ◽  
Mi-Sun Lee ◽  
Weibin Zhou
Keyword(s):  
Kidney Injury ◽  
Small Gtpase ◽  
Glomerular Sclerosis ◽  
Transgenic Zebrafish ◽  
Dependent Manner ◽  
Podocyte Injury ◽  
Filtration Barrier ◽  
Foot Process Effacement ◽  
Rac1 Activity ◽  
Foot Process

Activation of small GTPase Rac1 in podocytes is associated with rodent models of kidney injury and familial nephrotic syndrome. Induced Rac1 activation in podocytes in transgenic mice results in rapid transient proteinuria and foot process effacement, but not glomerular sclerosis. Thus it remains an open question whether abnormal activation of Rac1 in podocytes is sufficient to cause permanent podocyte damage. Using a number of transgenic zebrafish models, we showed that moderate elevation of Rac1 activity in podocytes did not impair the glomerular filtration barrier but aggravated metronidazole-induced podocyte injury, while inhibition of Rac1 activity ameliorated metronidazole-induced podocyte injury. Furthermore, a further increase in Rac1 activity in podocytes was sufficient to cause proteinuria and foot process effacement, which resulted in edema and lethality in juvenile zebrafish. We also found that activation of Rac1 in podocytes significantly downregulated the expression of nephrin and podocin, suggesting an adverse effect of Rac1 on slit diaphragm protein expression. Taken together, our data have demonstrated a causal link between excessive Rac1 activity and podocyte injury in a dosage-dependent manner, and transgenic zebrafish of variable Rac1 activities in podocytes may serve as useful animal models for the study of Rac1-related podocytopathy.

scholarly journals AMP-Kinase mediates regulation of glomerular volume and podocyte survival

2021 ◽  
Author(s):  
Khadija Banu ◽  
Qisheng Lin ◽  
John M Basgen ◽  
Marina Planoutene ◽  
Chengguo Wei ◽  
...  
Keyword(s):  
Protective Role ◽  
Negative Regulator ◽  
Amp Kinase ◽  
Glomerular Injury ◽  
Podocyte Injury ◽  
Kinase Activation ◽  
Glomerular Volume ◽  
Foot Process ◽  
Injury Models

We reported that Shroom3 knockdown, via Fyn inhibition, induced albuminuria with foot process effacement (FPE) without glomerulosclerosis (FSGS) or podocytopenia. Interestingly, knockdown mice had reduced podocyte volumes. Human minimal change disease, where podocyte Fyn inactivation was reported, also showed lower glomerular volumes than FSGS. We hypothesized that lower glomerular volume prevented the progression to podocytopenia. To test this hypothesis, we utilized unilateral- and 5/6th nephrectomy models in Shroom3 knockdown mice. Knockdown mice exhibited lower glomerular volume, and less glomerular and podocyte hypertrophy after nephrectomy. FYN-knockdown podocytes had similar reductions in podocyte volume, implying Fyn was downstream of Shroom3. Using SHROOM3- or FYN-knockdown, we confirmed reduced podocyte protein content, along with significantly increased phosphorylated AMP-kinase, a negative regulator of anabolism. AMP-Kinase activation resulted from increased cytoplasmic redistribution of LKB1 in podocytes. Inhibition of AMP-Kinase abolished the reduction in glomerular volume and induced podocytopenia in mice with FPE, suggesting a protective role for AMP-Kinase activation. In agreement with this, treatment of glomerular injury models with AMP-Kinase activators restricted glomerular volume, podocytopenia and progression to FSGS. In summary, we demonstrate the important role of AMP-Kinase in glomerular volume regulation and podocyte survival. Our data suggest that AMP-Kinase activation adaptively regulates glomerular volume to prevent podocytopenia in the context of podocyte injury.

scholarly journals Tangeretin Ameliorates Glucose-Induced Podocyte Injury through Blocking Epithelial to Mesenchymal Transition Caused by Oxidative Stress and Hypoxia

2020 ◽  
Vol 21 (22) ◽  
pp. 8577
Author(s):  
Min-Kyung Kang ◽  
Soo-Il Kim ◽  
Su Yeon Oh ◽  
Woojin Na ◽  
Young-Hee Kang
Keyword(s):  
Oxidative Stress ◽  
Epithelial To Mesenchymal Transition ◽  
Slit Diaphragm ◽  
Ros Production ◽  
Podocyte Injury ◽  
Mesenchymal Transition ◽  
Foot Process Effacement ◽  
In Vivo Animal Model ◽  
Foot Process ◽  
Junction Proteins

Podocyte injury inevitably results in leakage of proteins from the glomerular filter and is vital in the pathogenesis of diabetic nephropathy (DN). The underlying mechanisms of podocyte injury facilitate finding of new therapeutic targets for DN treatment and prevention. Tangeretin is an O-polymethoxylated flavone present in citrus peels with anti-inflammatory and antioxidant properties. This study investigated the renoprotective effects of tangeretin on epithelial-to-mesenchymal transition-mediated podocyte injury and fibrosis through oxidative stress and hypoxia caused by hyperglycemia. Mouse podocytes were incubated in media containing 33 mM glucose in the absence and presence of 1–20 μM tangeretin for up to 6 days. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Non-toxic tangeretin inhibited glucose-induced expression of the mesenchymal markers of N-cadherin and α-smooth muscle actin in podocytes. However, the reduced induction of the epithelial markers of E-cadherin and P-cadherin was restored by tangeretin in diabetic podocytes. Further, tangeretin enhanced the expression of the podocyte slit diaphragm proteins of nephrin and podocin down-regulated by glucose stimulation. The transmission electron microscopic images revealed that foot process effacement and loss of podocytes occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of slit junction and adherenes junction proteins. Glucose enhanced ROS production and HIF-1α induction in podocytes, leading to induction of oxidative stress and hypoxia. Similarly, in diabetic glomeruli reactive oxygen species (ROS) production and HIF-1α induction were observed. Furthermore, hypoxia-evoking cobalt chloride induced epithelial-to-mesenchymal transition (EMT) process and loss of slit diaphragm proteins and junction proteins in podocytes, which was inhibited by treating submicromolar tangeretin. Collectively, these results demonstrate that tangeretin inhibited podocyte injury and fibrosis through blocking podocyte EMT caused by glucose-induced oxidative stress and hypoxia.

scholarly journals Tangeretin Ameliorates Podocyte Injury Through Blocking Epithelial to Mesenchymal Transition in High Glucose-exposed Podocytes and Diabetic Kidneys (P06-009-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Min-Kyung Kang ◽  
Young-Hee Kang
Keyword(s):  
Epithelial Cells ◽  
High Glucose ◽  
Epithelial To Mesenchymal Transition ◽  
Kidney Tissue ◽  
Slit Diaphragm ◽  
Podocyte Injury ◽  
Mesenchymal Transition ◽  
Tissue Sections ◽  
Foot Process Effacement ◽  
Foot Process

Abstract Objectives Epithelial to mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties. This process contributes to the accumulation of matrix proteins in kidney and leads to renal glomeruli fibrosis. Tangeretin is an O-polymethoxylated flavone with anti-inflammatory and antioxidant properties that is found in citrus peels. This study investigated the renoprotective effects of tangeretin on EMT-mediated podocyte injury and fibrosis caused by hyperglycemia. Methods Mouse glomerular epithelial cells (podocyte) were incubated in media containing 5.5 mM glucose, 27.5 mM mannitol as an osmotic control or 33 mM glucose (high glucose) in the absence and presence of 1–20 μM tangeretin for up to 4 days. Antibodies of E-cadherin, N-cadherin, α-SMA, nephrin, podocin, P-cadherin and collagen1 were used for Western blotting. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Kidney tissue extracts of were Western-blotted, and tissue sections cut down in 5 µM thickness were immunohistochemically stained. In addition, kidney tissue sections (ultrathin sections, 70 nm) were observed with transmission electron microscopy (TEM). Results Non-toxic tangeretin enhanced expression of the podocyte slit diaphragm proteins of nephrin, podocin and P-cadherin down-regulated by glucose stimulation. Also, tangeretin inhibited high glucose-induced expression of the mesenchymal markers of N-cadherin and α-smooth muscle actin, whereas the induction of the epithelial marker E-cadherin was enhanced. Furthermore tangeretin attenuated the fibronectin induction and collagen production elevated by the presence of high glucose. The TEM images revealed that podocyte foot process effacement occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of glomerular slit junction proteins. Conclusions These results demonstrated that tangeretin maintained the structures of podocyte slit diaphragm in a robust form, and inhibited podocyte injury through blocking epithelial to mesenchymal transition of podocytes. Therefore, tangeretin may be a potent renoprotective agent counteracting diabetes-associated loss of podocyte slit diaphragm and maintaining glomerular filtration barrier. Funding Sources This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MEST) (NRF-2017R1A6A3A04011473).

scholarly journals Podocyte Foot Process Effacement in Postreperfusion Allograft Biopsies

2014 ◽  
Vol 97 (7) ◽  
pp. e38-e39
Author(s):  
George W. Burke ◽  
Jei-Wen Chang ◽  
Victoriano Pardo ◽  
Junichiro Sageshima ◽  
Linda Chen ◽  
...  
Keyword(s):  
Foot Process Effacement ◽  
Foot Process

scholarly journals Astragalus membranaceus and Panax notoginseng, the Novel Renoprotective Compound, Synergistically Protect against Podocyte Injury in Streptozotocin-Induced Diabetic Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Ruonan Zhai ◽  
Guihua Jian ◽  
Teng Chen ◽  
Ling Xie ◽  
Rui Xue ◽  
...  
Keyword(s):  
Panax Notoginseng ◽  
Diabetic Rats ◽  
Astragalus Membranaceus ◽  
Protective Effects ◽  
The Novel ◽  
Podocyte Injury ◽  
Renal Histopathology ◽  
Foot Process ◽  
Immunofluorescence Labeling ◽  
Renal Expression

This study was aimed at investigating the synergistical protective effects of Astragalus membranaceus (AG) and Panax notoginseng (NG) on podocyte injury in diabetic rats. Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin at 55 mg/kg. Diabetic rats were then orally administrated with losartan, AG, NG, and AG plus NG (2 : 1) for 12 weeks. Albuminuria, biochemical markers, renal histopathology, and podocyte number per glomerulus were measured. Podocyte apoptosis was determined by triple immunofluorescence labeling including TUNEL assay, WT1, and DAPI. Renal expression of nephrin, α-dystroglycan, Bax, Bcl-xl, and Nox4 was evaluated by immunohistochemistry, western blot, and RT-PCR. AG plus NG ameliorated albuminuria, renal histopathology, and podocyte foot process effacement to a greater degree than did AG or NG alone. The number of podocytes per glomerulus, as well as renal expression of nephrin, α-dystroglycan, and Bcl-xl, was decreased, while podocyte apoptosis, as well as renal expression of Bax and Nox4, was increased in diabetic rats. All of these abnormalities were partially restored by AG plus NG to a greater degree than did AG or NG alone. In conclusion, AG and NG synergistically ameliorated diabetic podocyte injury partly through upregulation of nephrin, α-dystroglycan, and Bcl-xl, as well as downregulation of Bax and Nox4. These findings might provide a novel treatment combination for DN.

scholarly journals P0338CRUMBS HOMOLOG2-EZRIN SIGNALING INDUCED PODOCYTE INJURY, LEADING TO MINIMAL-CHANGE DISEASE(MCD) AND FOCAL SEGMENTAL GLOMERULOSCLEROSIS(FSGS)

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Ichiro Hada
Keyword(s):  
Electron Microscopy ◽  
Nephrotic Syndrome ◽  
Cell Line ◽  
Focal Segmental Glomerulosclerosis ◽  
Minimal Change Disease ◽  
Immunofluorescence Microscopy ◽  
Minimal Change ◽  
Podocyte Injury ◽  
Heavy Proteinuria ◽  
Foot Process

Abstract Background and Aims The etiology and cellular pathogenesis of podocyte injury leading to minimal-change disease (MCD) and focal segmental glomerulosclerosis (FSGS) remain largely obscure. Genetic mutation of crumbs homolog 2 (CRB2) is a cause of congenital nephrotic syndrome. Type-1 transmembrane proteins including CRB2 transduce outside-in signals that are involved in various cellular events including changes in the cytoskeletal network. The aim of the present study is to determine whether alteration of CRB2-mediated signaling in podocytes causes MCD and FSGS. Method Mice were immunized with a partial recombinant protein including the extracellular part of mouse CRB2. Urinalysis was obtained, and the kidney was subjected to histopathology. Kidney samples were also subjected to immunofluorescence microscopy and glomerular isolation to determine whether activation of the ezrin/radixin/moesin (ERM) family of cross-linkers between plasma membrane proteins and the actin cytoskeleton is involved in the pathogenesis of this nephrotic model. A CRB2-expressing mouse podocyte cell line was generated and incubated with anti-CRB2 antibody, and cell lysates were subjected to immunoblot analysis of ERM phosphorylation. The presence of anti-CRB2 antibody in the serum was determined by Western blot analysis. Results Apparent anti-CRB2 antibody was detected in the serum from 4 weeks onward. Immunized mice developed proteinuria at 4 weeks, which continued at least until 29 weeks. Mice developing extremely heavy proteinuria also developed hematuria from 18 weeks onward. Light microscopy revealed MCD in mice with proteinuria alone and FSGS in mice with heavy proteinuria and hematuria. Immunofluorescence microscopy revealed positive granular IgG staining in podocyte foot processes, but not complement C3. Electron microscopy and immuno-electron microscopy revealed alteration of actin organization associated with prominent foot process effacement. Strong phosphorylation of ezrin was observed in the glomerulus from the proteinuric stage and in the cellular lysates from the CRB2-expressing podocyte cell line incubated with anti-CRB2 antibody. Conclusion The current data revealed that binding of anti-CRB2 antibody to the extracellular domain of CRB2 on the podocyte foot process activated the ezrin-cytoskeleton network, leading to podocyte injury. Our data also indicated that signaling by this one molecular can induce two different phenotypes of glomerular injury: MCD and FSGS. In our model, the signaling was activated by anti-CRB2 antibody, but in patients with nephrotic syndrome the CRB2 ligands remain unknown. Therefore, it will be important to identify the soluble factors interacting with CRB2, which may be novel factors contributing to the pathogenesis of MCD and FSGS.

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