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Advanced Science (Weinheim,... Mar 2024Podocytes are particularly sensitive to lipid accumulation, which has recently emerged as a crucial pathological process in the progression of proteinuric kidney...
Podocytes are particularly sensitive to lipid accumulation, which has recently emerged as a crucial pathological process in the progression of proteinuric kidney diseases like diabetic kidney disease and focal segmental glomerulosclerosis. However, the underlying mechanism remains unclear. Here, podocytes predominantly expressed protein dedicator of cytokinesis 5 (Dock5) is screened to be critically related to podocyte lipid lipotoxicity. Its expression is reduced in both proteinuric kidney disease patients and mouse models. Podocyte-specific deficiency of Dock5 exacerbated podocyte injury and glomeruli pathology in proteinuric kidney disease, which is mainly through modulating fatty acid uptake by the liver X receptor α (LXRα)/scavenger receptor class B (CD36) signaling pathway. Specifically, Dock5 deficiency enhanced CD36-mediated fatty acid uptake of podocytes via upregulating LXRα in an m A-dependent way. Moreover, the rescue of Dock5 expression ameliorated podocyte injury and proteinuric kidney disease. Thus, the findings suggest that Dock5 deficiency is a critical contributor to podocyte lipotoxicity and may serve as a promising therapeutic target in proteinuric kidney diseases.
Topics: Mice; Animals; Humans; Podocytes; Lipid Metabolism; Kidney Diseases; Fatty Acids; Lipids; Guanine Nucleotide Exchange Factors
PubMed: 38161229
DOI: 10.1002/advs.202306365 -
FEBS Open Bio Aug 2020Smad3 signaling and transgelin expression are often activated during puromycin aminonucleoside (PAN)-induced podocyte injury. Here, we investigated whether the Smad3...
Smad3 signaling and transgelin expression are often activated during puromycin aminonucleoside (PAN)-induced podocyte injury. Here, we investigated whether the Smad3 inhibitor SIS3 can ameliorate damage to injured podocytes. A model of PAN-induced podocyte injury was constructed using the MPC5 cell line. The effects of SIS3 on the expression of the podocyte cytoskeletal proteins transgelin, p15 , phosphor-smad3, phosphor-JAK/stat3, the apoptotic marker cleaved caspase 3, and c-myc were investigated using western blot. The distribution of F-actin in PAN-induced podocyte injury was observed under an immunofluorescence microscope. PAN-induced podocyte injury altered the distribution of F-actin and transgelin, and colocalization of these two proteins was observed. Transgelin expression and Smad3 phosphorylation were increased in the MPC5 cell line with prolonged PAN treatment. In addition, c-myc expression, p15 , and JAK phosphorylation were all increased after treatment with PAN. Treatment with the Smad3 inhibitor SIS3 reversed these phenomena and protected against PAN-induced podocyte injury. Moreover, stimulating podocytes directly with TGFβ-1 also led to enhanced expression of transgelin or phosphor-JAK/stat3, and this could be inhibited by SIS3. In conclusion, transgelin expression was induced through the Smad3 signaling pathway during PAN-induced podocyte injury, and the resulting abnormal distribution of F-actin and the enhanced expression of transgelin could be reversed by blockade of this pathway.
Topics: Animals; Cells, Cultured; Isoquinolines; Mice; Podocytes; Puromycin Aminonucleoside; Pyridines; Pyrroles; Smad3 Protein
PubMed: 32583562
DOI: 10.1002/2211-5463.12916 -
BMC Nephrology Aug 2019New non-invasive biomarkers are demanded to identify renal damage in various autoimmune-associated kidney diseases. Glomerular podocyte damage mediated by systemic lupus...
BACKGROUND
New non-invasive biomarkers are demanded to identify renal damage in various autoimmune-associated kidney diseases. Glomerular podocyte damage mediated by systemic lupus erythematosus (SLE) plays an important role in the pathogenesis and progression of lupus nephritis (LN). This study evaluated whether the podocyte-derived microparticles (MPs) were novel biomarkers of clinical and histological features in SLE patients with LN.
METHODS
A cross-sectional study, including 34 SLE patients and 16 healthy controls, was designed. Urinary annexin V podocalyxin MPs of all participants were quantified by flow cytometry. The correlation of podocyte-derived MPs with clinical and histological parameters of SLE patients was analysed.
RESULTS
The number of annexin V podocalyxin MPs from urine samples were markly increased in patients with SLE. Furthermore, the level of urinary podocyte-derived MPs was positively correlated with the SLE Disease Activity Index (SLEDAI) score, anti-dsDNA antibody titre, erythrocyte sedimentation rate, and proteinuria. Conversely, it was negatively correlated with the level of complement C3 and serum albumin. The number of urinary podocyte-derived MPs was significantly increased in SLE patients with high activity indices. Receiver operating characteristic (ROC) curves were calculated to assess the power for podocyte-derived MP levels in differentiating between SLE patients with and without LN. Podocyte-derived MP levels were able to differentiate between SLE patients with mild disease activity, as well as those with moderate and above disease activity. SLE patients showed increased podocyte-derived MP excretion into the urine.
CONCLUSIONS
These findings suggest that the change in urinary podocyte-derived MP levels could be useful for evaluating and monitoring SLE disease activity.
Topics: Annexin A5; Case-Control Studies; Cell-Derived Microparticles; Chi-Square Distribution; Cross-Sectional Studies; Female; Flow Cytometry; Humans; Lupus Erythematosus, Systemic; Lupus Nephritis; Male; Middle Aged; Podocytes; ROC Curve; Sialoglycoproteins; Statistics, Nonparametric
PubMed: 31382919
DOI: 10.1186/s12882-019-1482-z -
Human Molecular Genetics Oct 2009Urinary losses of macromolecules in nephrotic syndrome (NS) reflect a dysfunction of the highly permselective glomerular filtration barrier. Genetic studies of... (Review)
Review
Urinary losses of macromolecules in nephrotic syndrome (NS) reflect a dysfunction of the highly permselective glomerular filtration barrier. Genetic studies of hereditary forms of NS have led to the identification of proteins playing a crucial role in slit-diaphragm signalling, regulation of actin cytoskeleton dynamics, maintenance of podocyte integrity and cell-matrix interactions. This review will focus on recent molecular and clinical findings in the field of genetics of NS, thereby providing a better understanding of the complex glomerular filtration barrier physiology.
Topics: Animals; Cell-Matrix Junctions; Humans; Lysosomes; Mitochondria; Molecular Biology; Nephrotic Syndrome; Podocytes
PubMed: 19808795
DOI: 10.1093/hmg/ddp328 -
Science Advances Jun 2018In the healthy kidney, specialized cells called podocytes form a sophisticated blood filtration apparatus that allows excretion of wastes and excess fluid from the blood...
In the healthy kidney, specialized cells called podocytes form a sophisticated blood filtration apparatus that allows excretion of wastes and excess fluid from the blood while preventing loss of proteins such as albumin. To operate effectively, this filter is under substantial hydrostatic mechanical pressure. Given their function, it is expected that the ability to apply mechanical force is crucial to the survival of podocytes. However, to date, podocyte mechanobiology remains poorly understood, largely because of a lack of experimental data on the forces involved. We perform quantitative, continuous, nondisruptive, and high-resolution measurements of the forces exerted by differentiated podocytes in real time using a recently introduced functional imaging modality for continuous force mapping. Using an accepted model for podocyte injury, we find that injured podocytes experience near-complete loss of cellular force transmission but that this loss of force is reversible under certain conditions. The observed changes in force correlate with F-actin rearrangement and reduced expression of podocyte-specific proteins. By introducing robust and high-throughput mechanical phenotyping and by demonstrating the significance of mechanical forces in podocyte injury, this research paves the way to a new level of understanding of the kidney. In addition, in an advance over established force mapping techniques, we integrate cellular force measurements with immunofluorescence and perform continuous long-term force measurements of a cell population. Hence, our approach has general applicability to a wide range of biomedical questions involving mechanical forces.
Topics: Animals; Biomarkers; Biomechanical Phenomena; Cell Differentiation; Cytoskeleton; Fluorescent Antibody Technique; Humans; Mechanotransduction, Cellular; Mice; Phenotype; Podocytes; Stress, Physiological
PubMed: 29963620
DOI: 10.1126/sciadv.aap8030 -
Journal of Cellular Physiology Nov 2009Hyperglycemia and deriving from glomerular hypertension mechanical stress are the key factors underlying pathogenesis of diabetic nephropathy (DN). Multiple direct and... (Review)
Review
Hyperglycemia and deriving from glomerular hypertension mechanical stress are the key factors underlying pathogenesis of diabetic nephropathy (DN). Multiple direct and secondary effects of both these factors are mediated by complex signaling pathways with extensive interactions. The common signaling pathways stimulated by high glucose and mechanical insult may act in an additive manner, thereby accelerating the cell damage. Podocytes, the cells covering the outer aspect of glomerular basement membrane (GBM), are subjected not only to the load of filtered glucose but also to diverse mechanical forces. Bulging into the Bowman's space, they have no support from the apical side, which makes them particularly susceptible to the effects of mechanical strain. Both high glucose and mechanical stress may impair the protein systems anchoring the podocyte foot processes in GBM, therefore blunting resistance of these cells to mechanical forces. Modulation by these factors of expression and activity of numerous structural and functional proteins results in the (auto)inflammatory responses, dysfunction, apoptosis or necrosis of the podocytes. Loss of the podocytes is irreversible due to their inability to proliferate and to replenish damaged cells. Podocytes are injured early in the course of DN, which, most likely, underlies further glomerular and renal damage in diabetes. This review summarizes the effects of elevated glucose and mechanical stress that seem to be involved in podocyte impairment in diabetes, with particular focus on the possible interactions between these factors.
Topics: Animals; Biological Transport; Glucose; Humans; Hyperglycemia; Inflammation; Podocytes; Stress, Mechanical
PubMed: 19562677
DOI: 10.1002/jcp.21856 -
Journal of Receptor and Signal... Jun 2020The aim of our study is to investigate the relationship between podocyte autophagy and apoptosis induced by Puromycin Aminonucleoside (PAN) and to clarify its...
The aim of our study is to investigate the relationship between podocyte autophagy and apoptosis induced by Puromycin Aminonucleoside (PAN) and to clarify its mechanism. Podocytes were cultured . The apoptosis rates of each group were detected using flow cytometry. The expression of LC3-II protein and changes in distribution were detected through laser scanning confocal microscope, and the western blot protocol was employed for detection of protein expression of LC3-II. The autophagosomes were detected by transmission electron microscopy. In this study, We found that autophagosome increased followed by apoptosis after podocyte injury. Furthermore, we conformed that the activation of autophagy could inhibit the apoptosis to alleviate the injury of podocyte at an early stage. Autophagy occurred earlier before apoptosis and autophagy mediated podocyte apoptosis induced by PAN. These findings indicate that autophagy may become a novel therapeutic target for the treatment of podocyte injury and proteinuria in the future.
Topics: Animals; Apoptosis; Autophagosomes; Autophagy; Blotting, Western; Cell Shape; Cells, Cultured; Mice; Podocytes; Puromycin Aminonucleoside; Time Factors
PubMed: 32102592
DOI: 10.1080/10799893.2020.1731536 -
Kidney International Jun 2023Polat et al. report that mice with a podocyte-specific expression of a constitutively active Rac1 form displayed similar injury and albuminuria, regardless of transient...
Polat et al. report that mice with a podocyte-specific expression of a constitutively active Rac1 form displayed similar injury and albuminuria, regardless of transient receptor potential canonical 5 activity. This article confirms the pathogenic role of deregulated Rac1 and challenges models involving the role of transient receptor potential canonical 5 in podocytes. We learned from this study and propose a roadmap for this controversial field to help new drug candidates succeed in clinical trials and safely reach patients.
Topics: Mice; Animals; Podocytes; Albuminuria
PubMed: 36948398
DOI: 10.1016/j.kint.2023.03.008 -
Nephrology (Carlton, Vic.) Apr 2014Heparin, a highly sulfated glycosaminoglycan, has been shown to have a renoprotective effect on renal diseases, but its mechanisms remain to be elucidated. In this...
AIM
Heparin, a highly sulfated glycosaminoglycan, has been shown to have a renoprotective effect on renal diseases, but its mechanisms remain to be elucidated. In this study, we examined the effect of heparin on podocytes by using primary cultured podocytes positive for podocyte-specific markers including podocin and podocalyxin.
METHODS
Podocytes were cultured from highly purified glomeruli isolated by the method with renal perfusion with magnetic beads and digestion of collagenase. Podocyte-specific gene expressions and proteins were examined by real-time polymerase chain reaction (PCR), Western blotting and immunofluorescence microscopy.
RESULTS
Real-time PCR showed that addition of heparin to the culture media significantly upregulated most of the podocyte-specific genes in a dose-dependent and time-dependent manner. Western blotting showed a marked increase in protein levels of nephrin and podocin. Podocin localization at cell-cell contact sites became conspicuous in the presence of heparin. The effect of heparin was observed even in culture media deprived of bovine foetal serum. Heparan sulfate, less sulfated than heparin, and hyaluronan did not show such effects, but sulfated dextran did markedly.
CONCLUSION
Heparin acts on cultured podocytes to increase podocyte-specific gene expressions. A high degree of sulfation is crucial for the effect of heparin.
Topics: Animals; Cells, Cultured; Dextran Sulfate; Dose-Response Relationship, Drug; Gene Expression Regulation; Heparin; Heparitin Sulfate; Hyaluronic Acid; Intracellular Signaling Peptides and Proteins; Male; Membrane Proteins; Podocytes; Primary Cell Culture; RNA, Messenger; Rats, Wistar; Time Factors; Up-Regulation
PubMed: 24433416
DOI: 10.1111/nep.12207 -
Biochemical and Biophysical Research... Nov 2018Podocyte depletion is a central pathological mechanism of diabetic nephropathy (DN). Hyperglycemia induced podocyte apoptosis, resulting in podocyte depletion. However,...
Podocyte depletion is a central pathological mechanism of diabetic nephropathy (DN). Hyperglycemia induced podocyte apoptosis, resulting in podocyte depletion. However, the crucial mechanism of hyperglycemia-induced podocyte apoptosis remains poorly understood. In this study, we evaluated the expression of septin 7, a GTP-binding protein, in glomerular podocytes of patients and mice with DN, and investigated the pro-apoptotic effect of septin 7 on high glucose (HG) induced podocyte apoptosis in vitro. We found septin 7 expression was markedly increased not only in glomerular podocytes of patients and db/db mice with DN but also in cultured podocytes with HG stimulation. Knocking down septin 7 with siRNA could attenuate HG induced podocytes apoptosis and excessive intracellular Ca concentration. This study revealed septin7 may potentially play a proapoptotic role in podocyte under diabetic conditions and may provide a potential target for preventing podocyte apoptosis in DN.
Topics: Animals; Apoptosis; Calcium; Cell Cycle Proteins; Cells, Cultured; Diabetic Nephropathies; Gene Knockdown Techniques; Glucose; Humans; Intracellular Space; Male; Mice, Inbred C57BL; Microfilament Proteins; Podocytes; Septins
PubMed: 30361092
DOI: 10.1016/j.bbrc.2018.10.081