scholarly journals The podocyte-specific knockout of palladin in mice with a 129 genetic background affects podocyte morphology and the expression of palladin interacting proteins

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260878
Author(s):  
Nadine Artelt ◽  
Alina M. Ritter ◽  
Linda Leitermann ◽  
Felix Kliewe ◽  
Rabea Schlüter ◽  
...  
Keyword(s):  
Genetic Background ◽  
Kidney Diseases ◽  
Morphological Changes ◽  
Close Contact ◽  
Actin Binding ◽  
Interacting Proteins ◽  
Filtration Barrier ◽  
Parietal Epithelial Cells ◽  
Old Mice

Proper and size selective blood filtration in the kidney depends on an intact morphology of podocyte foot processes. Effacement of interdigitating podocyte foot processes in the glomeruli causes a leaky filtration barrier resulting in proteinuria followed by the development of chronic kidney diseases. Since the function of the filtration barrier is depending on a proper actin cytoskeleton, we studied the role of the important actin-binding protein palladin for podocyte morphology. Podocyte-specific palladin knockout mice on a C57BL/6 genetic background (PodoPalldBL/6-/-) were back crossed to a 129 genetic background (PodoPalld129-/-) which is known to be more sensitive to kidney damage. Then we analyzed the morphological changes of glomeruli and podocytes as well as the expression of the palladin-binding partners Pdlim2, Lasp-1, Amotl1, ezrin and VASP in 6 and 12 months old mice. PodoPalld129-/- mice in 6 and 12 months showed a marked dilatation of the glomerular tuft and a reduced expression of the mesangial marker protein integrin α8 compared to controls of the same age. Furthermore, ultrastructural analysis showed significantly more podocytes with morphological deviations like an enlarged sub-podocyte space and regions with close contact to parietal epithelial cells. Moreover, PodoPalld129-/- of both age showed a severe effacement of podocyte foot processes, a significantly reduced expression of pLasp-1 and Pdlim2, and significantly reduced mRNA expression of Pdlim2 and VASP, three palladin-interacting proteins. Taken together, the results show that palladin is essential for proper podocyte morphology in mice with a 129 background.

scholarly journals A new function for parietal epithelial cells: a second glomerular barrier

2009 ◽  
Vol 297 (6) ◽  
pp. F1566-F1574 ◽  
Author(s):  
Takamoto Ohse ◽  
Alice M. Chang ◽  
Jeffrey W. Pippin ◽  
George Jarad ◽  
Kelly L. Hudkins ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Basement Membrane ◽  
Glomerular Filtration ◽  
Glomerular Filtration Barrier ◽  
Impermeable Barrier ◽  
Filtration Barrier ◽  
Proximal Tubular ◽  
Parietal Epithelial Cells ◽  
Glomerular Barrier

The functional role of glomerular parietal epithelial cells (PECs) remains poorly understood. To test the hypothesis that PECs form an impermeable barrier to filtered protein through the formation of tight junctions (TJ), studies were performed in normal animals and in the anti-glomerular basement membrane (GBM) model of crescentic nephritis. Electron microscopy showed well-defined TJ between PECs in normal mice, which no longer could be identified when these cells became extensively damaged or detached from their underlying Bowman's basement membrane. The TJ proteins claudin-1, zonula occludens-1, and occludin stained positive in PECs; however, staining decreased in anti-GBM disease. To show that these events were associated with increased permeability across the PEC-Bowman's basement membrane barrier, control and diseased animals were injected intravenously with either Texas red-conjugated dextran (3 kDa) or ovalbumin (45 kDa) tracers. As expected, both tracers were readily filtered across the glomerular filtration barrier and taken up by proximal tubular cells. However, when the glomerular filtration barrier was injured in anti-GBM disease, tracers were taken up by podocytes and PECs. Moreover, tracers were also detected between PECs and the underlying Bowman's basement membrane, and in many instances were detected in the extraglomerular space. We propose that together with its underlying Bowman's basement membrane, the TJ of PECs serve as a second barrier to protein. When disturbed following PEC injury, the increase in permeability of this layer to filtered protein is a mechanism underlying periglomerular inflammation characteristic of anti-GBM disease.

scholarly journals Remodeling of cellular cytoskeleton by the acid sphingomyelinase/ceramide pathway

2008 ◽  
Vol 181 (2) ◽  
pp. 335-350 ◽  
Author(s):  
Youssef H. Zeidan ◽  
Russell W. Jenkins ◽  
Yusuf A. Hannun
Keyword(s):  
Morphological Changes ◽  
Acid Sphingomyelinase ◽  
Dominant Negative ◽  
Actin Binding ◽  
Cytoskeletal Remodeling ◽  
Membrane Protrusions ◽  
Exogenous Delivery ◽  
Cellular Cytoskeleton ◽  
Transient Elevation

The chemotherapeutic agent cisplatin is widely used in treatment of solid tumors. In breast cancer cells, cisplatin produces early and marked changes in cell morphology and the actin cytoskeleton. These changes manifest as loss of lamellipodia/filopodia and appearance of membrane ruffles. Furthermore, cisplatin induces dephosphorylation of the actin-binding protein ezrin, and its relocation from membrane protrusions to the cytosol. Because cisplatin activates acid sphingomyelinase (ASMase), we investigate here the role of the ASMase/ceramide (Cer) pathway in mediating these morphological changes. We find that cisplatin induces a transient elevation in ASMase activity and its redistribution to the plasma membrane. This translocation is blocked upon overexpression of a dominant-negative (DN) ASMaseS508A mutant and by a DN PKCδ. Importantly; knockdown of ASMase protects MCF-7 cells from cisplatin-induced cytoskeletal changes including ezrin dephosphorylation. Reciprocally, exogenous delivery of D-e-C16-Cer, but not dihydro-C16-Cer, recapitulates the morphotropic effects of cisplatin. Collectively, these results highlight a novel tumor suppressor property for Cer and a function for ASMase in cisplatin-induced cytoskeletal remodeling.

scholarly journals Immunocytochemical localization of fibrinogen during thrombin-induced aggregation of washed human platelets

Blood ◽  
1988 ◽  
Vol 71 (5) ◽  
pp. 1310-1320
Author(s):  
H Suzuki ◽  
RL Kinlough-Rathbone ◽  
MA Packham ◽  
K Tanoue ◽  
H Yamazaki ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Close Contact ◽  
Human Platelets ◽  
Platelet Surface ◽  
Fibrin Formation ◽  
Low Concentrations ◽  
Gold Label ◽  
Lowicryl K4m ◽  
Induced Aggregation

Because thrombin aggregates afibrinogenemic platelets and platelets from patients with the gray platelet syndrome and because antibodies to fibrinogen inhibit thrombin-induced aggregation only at low concentrations of thrombin, the role of fibrinogen in the formation of thrombin-induced aggregates was investigated further with human platelets washed and resuspended in Tyrode-albumin solution containing apyrase, either with or without added Ca2+ (2 mmol/L). Samples for immunocytochemical assessment of fibrinogen distribution were taken at several times (up to five minutes) after aggregation induced by 0.5 U/mL of thrombin. Glutaraldehyde-fixed samples were embedded in Lowicryl K4M, sectioned, incubated with goat antihuman fibrinogen, washed, reacted with gold-labeled antigoat IgG, and prepared for electron microscopy. By 10 seconds, small aggregates formed, and granules were centralized; alpha granules were heavily labeled with immunogold, but the platelet surface was not. As large aggregates formed, granule swelling or fusion occurred, and in some areas granule material seemed to be in contact with the exterior. In these experiments with no added fibrinogen, there were some clusters of gold particles on the platelet surfaces remote from sites of granule discharge, but there were large areas where platelets were in close contact with little or no fibrinogen detectable between them. No fibrin was visible up to five minutes after the addition of thrombin, which indicated that fibrinogen from the granules does not readily become available for fibrin formation in the ambient fluid. Similar results were obtained in media with and without added Ca2+. Thus at least some aggregation in response to thrombin can occur without the participation of released fibrinogen, and much of the granule fibrinogen appears to remain localized at sites where granules fuse with the plasma membrane or the open canalicular system. Incubation of unstirred samples with thrombin for ten minutes resulted in the formation of small aggregates, extensive gold label in regions connected to the exterior of the platelets, but very little gold labeling of the platelet membrane and no visible fibrin formation. When the platelets were aggregated in the presence of external fibrinogen, the morphological changes within the platelets were the same, but fibrinogen rapidly became associated with the entire platelet surface, and visible fibrin formed within 30 seconds in the medium containing 2 mmol/L Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS).

scholarly journals Immunocytochemical localization of fibrinogen during thrombin-induced aggregation of washed human platelets

Blood ◽  
1988 ◽  
Vol 71 (5) ◽  
pp. 1310-1320 ◽  
Author(s):  
H Suzuki ◽  
RL Kinlough-Rathbone ◽  
MA Packham ◽  
K Tanoue ◽  
H Yamazaki ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Close Contact ◽  
Human Platelets ◽  
Platelet Surface ◽  
Fibrin Formation ◽  
Low Concentrations ◽  
Gold Label ◽  
Lowicryl K4m ◽  
Induced Aggregation

Abstract Because thrombin aggregates afibrinogenemic platelets and platelets from patients with the gray platelet syndrome and because antibodies to fibrinogen inhibit thrombin-induced aggregation only at low concentrations of thrombin, the role of fibrinogen in the formation of thrombin-induced aggregates was investigated further with human platelets washed and resuspended in Tyrode-albumin solution containing apyrase, either with or without added Ca2+ (2 mmol/L). Samples for immunocytochemical assessment of fibrinogen distribution were taken at several times (up to five minutes) after aggregation induced by 0.5 U/mL of thrombin. Glutaraldehyde-fixed samples were embedded in Lowicryl K4M, sectioned, incubated with goat antihuman fibrinogen, washed, reacted with gold-labeled antigoat IgG, and prepared for electron microscopy. By 10 seconds, small aggregates formed, and granules were centralized; alpha granules were heavily labeled with immunogold, but the platelet surface was not. As large aggregates formed, granule swelling or fusion occurred, and in some areas granule material seemed to be in contact with the exterior. In these experiments with no added fibrinogen, there were some clusters of gold particles on the platelet surfaces remote from sites of granule discharge, but there were large areas where platelets were in close contact with little or no fibrinogen detectable between them. No fibrin was visible up to five minutes after the addition of thrombin, which indicated that fibrinogen from the granules does not readily become available for fibrin formation in the ambient fluid. Similar results were obtained in media with and without added Ca2+. Thus at least some aggregation in response to thrombin can occur without the participation of released fibrinogen, and much of the granule fibrinogen appears to remain localized at sites where granules fuse with the plasma membrane or the open canalicular system. Incubation of unstirred samples with thrombin for ten minutes resulted in the formation of small aggregates, extensive gold label in regions connected to the exterior of the platelets, but very little gold labeling of the platelet membrane and no visible fibrin formation. When the platelets were aggregated in the presence of external fibrinogen, the morphological changes within the platelets were the same, but fibrinogen rapidly became associated with the entire platelet surface, and visible fibrin formed within 30 seconds in the medium containing 2 mmol/L Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS).

scholarly journals Txn1 mutation causes epilepsy associated with vacuolar degeneration in the midbrain

2021 ◽  
Author(s):  
Iori Ohmori ◽  
Mamoru Ouchida ◽  
Hirohiko Imai ◽  
Saeko Ishida ◽  
Shinya Toyokuni ◽  
...  
Keyword(s):  
Cell Death ◽  
Morphological Changes ◽  
Interacting Proteins ◽  
Wild Type ◽  
Vacuolar Degeneration ◽  
Juvenile Rats ◽  
The Central Nervous System ◽  
Reducing Activity ◽  
Spontaneous Repair

Thioredoxin (TXN), encoded by Txn1, acts as a critical antioxidant in the defense against oxidative stress by regulating the dithiol/disulfide balance of interacting proteins. The role of TXN in the central nervous system (CNS) is largely unknown. A phenotype-driven study of N-ethyl-N-nitrosourea-mutated rats with running seizures at around five-week of age revealed the relevance of Txn1 mutations to CNS disorders. Genetic mapping identified Txn1-F54L in epileptic rats. The insulin-reducing activity of Txn1-F54L rats was approximately one-third that of the wild-type. Vacuolar degeneration in the midbrain, mainly in the thalamus and the inferior colliculus, was observed in the Txn1-F54L rats. The lesions displayed neuronal and oligodendrocyte cell death. Neurons in Txn1-F54L rats showed morphological changes in the mitochondria. Vacuolar degeneration began at three weeks of age, and spontaneous repair began at seven weeks; a dramatic change from cell death to repair occurred in the midbrain during a restricted period. In conclusion, Txn1 is essential for the development of the midbrain in juvenile rats.

Altered expression of junctional adhesion molecule 4 in injured podocytes

2006 ◽  
Vol 290 (2) ◽  
pp. F335-F344 ◽  
Author(s):  
Yutaka Harita ◽  
Naoko Miyauchi ◽  
Tamaki Karasawa ◽  
Koichi Suzuki ◽  
Gi Dong Han ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Immunoelectron Microscopy ◽  
Adhesion Molecule ◽  
Apical Membrane ◽  
Morphological Changes ◽  
Puromycin Aminonucleoside ◽  
Altered Expression ◽  
Rat Models ◽  
Filtration Barrier

Recent investigations have revealed the importance of glomerular podocytes with its diaphragm as the major filtration barrier. Junctional adhesion molecule 4 (JAM4) has been identified as a protein that interacts with membrane-associated guanyl kinase inverted (MAGI)-1 and is reported to be expressed on podocytes. To elucidate the role of JAM4 on podocytes, we examined the expression of JAM4 and MAGI-1 in normal and two different proteinuric rat models: puromycin aminonucleoside (PAN) nephropathy and anti-nephrin antibody-induced (ANA) nephropathy, one model with and one without effacement of podocyte foot processes. JAM4 was detected by immunomicroscopy at the apical membrane of normal podocytes. JAM4 immunostaining was focally increased in the podocytes in PAN nephropathy but not in ANA nephropathy. In proteinuric podocytes, the expression of JAM4 was distinct from that of MAGI-1 or other slit diaphragm molecules such as nephrin and ZO-1. Close colocalization of JAM4 and ezrin was maintained in PAN nephropathy. By immunoelectron microscopy, the signals for JAM4 were detected at the free apical membrane of the podocytes with effaced foot processes. Studies with selective detergent extract revealed that the subcellular localization of JAM4 was altered in PAN nephropathy. Thus the altered expression of JAM4 appears to be associated with morphological changes in podocytes and can be a useful marker of injured podocytes. JAM4 may have a different role at the apical membrane besides the role as a junctional molecule and is likely associated with the unique structure of this epithelium.

scholarly journals Sphingosine-1-Phosphate Metabolism and Signaling in Kidney Diseases

2020 ◽  
Vol 32 (1) ◽  
pp. 9-31
Author(s):  
Yelena Drexler ◽  
Judith Molina ◽  
Alla Mitrofanova ◽  
Alessia Fornoni ◽  
Sandra Merscher
Keyword(s):  
Structural Integrity ◽  
Kidney Diseases ◽  
Second Messengers ◽  
Proper Function ◽  
Renal Cells ◽  
Glomerular Filtration Barrier ◽  
The Past ◽  
Filtration Barrier ◽  
Sphingosine 1 Phosphate

In the past few decades, sphingolipids and sphingolipid metabolites have gained attention because of their essential role in the pathogenesis and progression of kidney diseases. Studies in models of experimental and clinical nephropathies have described accumulation of sphingolipids and sphingolipid metabolites, and it has become clear that the intracellular sphingolipid composition of renal cells is an important determinant of renal function. Proper function of the glomerular filtration barrier depends heavily on the integrity of lipid rafts, which include sphingolipids as key components. In addition to contributing to the structural integrity of membranes, sphingolipid metabolites, such as sphingosine-1-phosphate (S1P), play important roles as second messengers regulating biologic processes, such as cell growth, differentiation, migration, and apoptosis. This review will focus on the role of S1P in renal cells and how aberrant extracellular and intracellular S1P signaling contributes to the pathogenesis and progression of kidney diseases.

Genetic background of cholesterol absorption efficacy. The role of Niemann–Pick C1-like 1 receptor and its genetic variation in lipid metabolism

2010 ◽  
Vol 151 (34) ◽  
pp. 1376-1383 ◽  
Author(s):  
Mariann Harangi ◽  
István Balogh ◽  
János Harangi ◽  
György Paragh
Keyword(s):  
Genetic Variation ◽  
Lipid Metabolism ◽  
Genetic Background ◽  
Cholesterol Absorption ◽  
Niemann Pick

A Niemann–Pick C1-like-1 egy szterolfelismerő domént tartalmazó membránfehérje, amelyet nagy számban expresszálnak csúcsi felszínükön a bélhámsejtek. Az utóbbi évek vizsgálatai azt igazolták, hogy ez a fehérje szükséges a szabad koleszterin bejutásához a bélhámsejtekbe a bél lumenéből. Biokémiai vizsgálatok azt igazolták, hogy a Niemann–Pick C1-like-1-hez kötődik az ezetimib, amely egy hatékony koleszterinfelszívódást gátló szer. A bélből történő koleszterinfelszívódás ütemében és az ezetimibkezelés hatékonyságában tapasztalt egyéni eltérések hátterében felmerült néhány Niemann–Pick C1-like-1 génvariáció oki szerepe.

SARS-COV2 virus and Coronavirus disease (COVID-19)

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 977-982
Author(s):  
Mohamed J. Saadh ◽  
Bashar Haj Rashid M ◽  
Roa’a Matar ◽  
Sajeda Riyad Aldibs ◽  
Hala Sbaih ◽  
...  
Keyword(s):  
Close Contact ◽  
Antiviral Agents ◽  
Health Concern ◽  
The Novel ◽  
Global Public Health ◽  
Fatal Disease ◽  
Mild Disease ◽  
Life Threatening ◽  
Novel Coronavirus

SARS-COV2 virus causes Coronavirus disease (COVID-19) and represents the causative agent of a potentially fatal disease that is of great global public health concern. The novel coronavirus (2019) was discovered in 2019 in Wuhan, the market of the wet animal, China with viral pneumonia cases and is life-threatening. Today, WHO announces COVID-19 outbreak as a pandemic. COVID-19 is likely to be zoonotic. It is transmitted from bats as intermediary animals to human. Also, the virus is transmitted from human to human who is in close contact with others. The computerized tomographic chest scan is usually abnormal even in those with no symptoms or mild disease. Treatment is nearly supportive; the role of antiviral agents is yet to be established. The SARS-COV2 virus spreads faster than its two ancestors, the SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), but has lower fatality. In this article, we aimed to summarize the transmission, symptoms, pathogenesis, diagnosis, treatment, and vaccine to control the spread of this fatal disease.

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