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Nature Communications Oct 2019Arctigenin (ATG) is a major component of Fructus Arctii, a traditional herbal remedy that reduced proteinuria in diabetic patients. However, whether ATG specifically...
Arctigenin (ATG) is a major component of Fructus Arctii, a traditional herbal remedy that reduced proteinuria in diabetic patients. However, whether ATG specifically provides renoprotection in DKD is not known. Here we report that ATG administration is sufficient to attenuate proteinuria and podocyte injury in mouse models of diabetes. Transcriptomic analysis of diabetic mouse glomeruli showed that cell adhesion and inflammation are two key pathways affected by ATG treatment, and mass spectrometry analysis identified protein phosphatase 2 A (PP2A) as one of the top ATG-interacting proteins in renal cells. Enhanced PP2A activity by ATG reduces p65 NF-κB-mediated inflammatory response and high glucose-induced migration in cultured podocytes via interaction with Drebrin-1. Importantly, podocyte-specific Pp2a deletion in mice exacerbates DKD injury and abrogates the ATG-mediated renoprotection. Collectively, our results demonstrate a renoprotective mechanism of ATG via PP2A activation and establish PP2A as a potential target for DKD progression.
Topics: Animals; Arctium; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Disease Progression; Furans; Humans; Lignans; Male; Mice; Mice, Knockout; Microscopy, Electron, Transmission; Nitric Oxide Synthase Type III; Podocytes; Protein Phosphatase 2; Streptozocin; Treatment Outcome
PubMed: 31586053
DOI: 10.1038/s41467-019-12433-w -
Kidney International Oct 2022Efficient therapies for diabetic kidney disease (DKD), now the leading cause of kidney failure, are lacking. One hallmark of DKD is sterile inflammation (inflammation in...
Efficient therapies for diabetic kidney disease (DKD), now the leading cause of kidney failure, are lacking. One hallmark of DKD is sterile inflammation (inflammation in absence of microorganisms), but the underlying molecular mechanisms remain poorly understood. The NLRP3 inflammasome (innate immune system receptors and sensors regulating activation of caspase-1) is a mechanism of sterile inflammation known to be activated by metabolic stimuli and reactive metabolites associated with DKD, including inflammasome activation in podocytes. However, whether NLRP3 inflammasome activation in podocytes contributes to sterile inflammation and glomerular damage in DKD remains unknown. Here, we found that kidney damage, as reflected by increased albuminuria, glomerular mesangial expansion and glomerular basement membrane thickness was aggravated in hyperglycemic mice with podocyte-specific expression of an Nlrp3 gain-of-function mutant (Nlrp3A350V). In contrast, hyperglycemic mice with podocyte-specific Nlrp3 or Caspase-1 deficiency showed protection against DKD. Intriguingly, podocyte-specific Nlrp3 deficiency was fully protective, while podocyte-specific caspase-1 deficiency was only partially protective. Podocyte-specific Nlrp3, but not caspase-1 deficiency, maintained glomerular autophagy in hyperglycemic mice, suggesting that podocyte Nlrp3 exerts both canonical and non-canonical effects. Thus, podocyte NLRP3 inflammasome activation is both sufficient and required for DKD and supports the concept that podocytes exert some immune cell-like functions. Hence, as podocyte NLRP3 exerts non-canonical and canonical effects, targeting NLRP3 may be a promising therapeutic approach in DKD.
Topics: Animals; Diabetes Mellitus; Diabetic Nephropathies; Inflammasomes; Inflammation; Mice; Mice, Obese; NLR Family, Pyrin Domain-Containing 3 Protein; Podocytes
PubMed: 35779608
DOI: 10.1016/j.kint.2022.06.010 -
Kidney360 Dec 2023As the population in many industrial countries is aging, the risk, incidence, and prevalence of CKD increases. In the kidney, advancing age results in a progressive... (Review)
Review
As the population in many industrial countries is aging, the risk, incidence, and prevalence of CKD increases. In the kidney, advancing age results in a progressive decrease in nephron number and an increase in glomerulosclerosis. In this review, we focus on the effect of aging on glomerular podocytes, the post-mitotic epithelial cells critical for the normal integrity and function of the glomerular filtration barrier. The podocytes undergo senescence and transition to a senescence-associated secretory phenotype typified by the production and secretion of inflammatory cytokines that can influence neighboring glomerular cells by paracrine signaling. In addition to senescence, the aging podocyte phenotype is characterized by ultrastructural and functional changes; hypertrophy; cellular, oxidative, and endoplasmic reticulum stress; reduced autophagy; and increased expression of aging genes. This results in a reduced podocyte health span and a shortened life span. Importantly, these changes in the pathways/processes characteristic of healthy podocyte aging are also often similar to pathways in the disease-induced injured podocyte. Finally, the better understanding of podocyte aging and senescence opens therapeutic options to slow the rate of podocyte aging and promote kidney health.
Topics: Humans; Podocytes; Aging; Kidney Glomerulus; Kidney Diseases; Epithelial Cells
PubMed: 37950369
DOI: 10.34067/KID.0000000000000284 -
Journal of the American Society of... Mar 2021Microscopic analysis of urine sediment is probably the most commonly used diagnostic procedure in nephrology. The urinary cells, however, have not yet undergone careful...
BACKGROUND
Microscopic analysis of urine sediment is probably the most commonly used diagnostic procedure in nephrology. The urinary cells, however, have not yet undergone careful unbiased characterization.
METHODS
Single-cell transcriptomic analysis was performed on 17 urine samples obtained from five subjects at two different occasions, using both spot and 24-hour urine collection. A pooled urine sample from multiple healthy individuals served as a reference control. In total 23,082 cells were analyzed. Urinary cells were compared with human kidney and human bladder datasets to understand similarities and differences among the observed cell types.
RESULTS
Almost all kidney cell types can be identified in urine, such as podocyte, proximal tubule, loop of Henle, and collecting duct, in addition to macrophages, lymphocytes, and bladder cells. The urinary cell-type composition was subject specific and reasonably stable using different collection methods and over time. Urinary cells clustered with kidney and bladder cells, such as urinary podocytes with kidney podocytes, and principal cells of the kidney and urine, indicating their similarities in gene expression.
CONCLUSIONS
A reference dataset for cells in human urine was generated. Single-cell transcriptomics enables detection and quantification of almost all types of cells in the kidney and urinary tract.
Topics: Aged; DNA Barcoding, Taxonomic; Female; Gene Library; Humans; Kidney; Kidney Diseases; Male; Middle Aged; Podocytes; RNA-Seq; Single-Cell Analysis; Transcriptome; Urinary Bladder; Urine
PubMed: 33531352
DOI: 10.1681/ASN.2020050757 -
Biomedicine & Pharmacotherapy =... Dec 2022Renal injury and the development of albuminuria are tightly connected with the loss of podocytes. Podocyte damages cause proteinuric renal diseases since podocyte foot... (Review)
Review
Renal injury and the development of albuminuria are tightly connected with the loss of podocytes. Podocyte damages cause proteinuric renal diseases since podocyte foot processes (FP) and their interposed slit diaphragms (SD) are the final barriers against protein loss. Podocyte effacement and the resultant deterioration of podocyte SD integrity that involve the active rearrangement of the podocyte actin cytoskeleton is a chief mechanism of proteinuric kidney diseases. The progress of these injuries can eventually lead to cell detachment and death. Due to the prominence of the actin cytoskeleton in maintaining glomerular filtration, the assessment of the molecular design and regulation of actin is a central target of podocyte research. In the current review, a comprehensive summary of the actin cytoskeleton, its constituents, and regulatory signaling pathways has been provided. Since actin-regulated cell plasticity is a crucial feature of normal podocyte function, and deteriorations in its dynamics seem to directly affect podocyte morphology and glomerular permeability, this review discusses cascades that regulate actin polymerization in podocytes.
Topics: Actins; Actin Cytoskeleton; Podocytes; Kidney Glomerulus; Intercellular Junctions
PubMed: 36411613
DOI: 10.1016/j.biopha.2022.113920 -
Nature Communications Mar 2022Although mature podocytes lack tight junctions, tight junction integral membrane protein claudin-5 (CLDN5) is predominantly expressed on plasma membranes of podocytes...
Although mature podocytes lack tight junctions, tight junction integral membrane protein claudin-5 (CLDN5) is predominantly expressed on plasma membranes of podocytes under normal conditions. Using podocyte-specific Cldn5 knockout mice, we identify CLDN5 as a crucial regulator of podocyte function and reveal that Cldn5 deletion exacerbates podocyte injury and proteinuria in a diabetic nephropathy mouse model. Mechanistically, CLDN5 deletion reduces ZO1 expression and induces nuclear translocation of ZONAB, followed by transcriptional downregulation of WNT inhibitory factor-1 (WIF1) expression, which leads to activation of WNT signaling pathway. Podocyte-derived WIF1 also plays paracrine roles in tubular epithelial cells, as evidenced by the finding that animals with podocyte-specific deletion of Cldn5 or Wif1 have worse kidney fibrosis after unilateral ureteral obstruction than littermate controls. Systemic delivery of WIF1 suppresses the progression of diabetic nephropathy and ureteral obstruction-induced renal fibrosis. These findings establish a function for podocyte CLDN5 in restricting WNT signaling in kidney.
Topics: Adaptor Proteins, Signal Transducing; Animals; Claudin-5; Diabetic Nephropathies; Fibrosis; Mice; Podocytes; Ureteral Obstruction; Wnt Signaling Pathway
PubMed: 35332151
DOI: 10.1038/s41467-022-29277-6 -
Profilin1 is required for prevention of mitotic catastrophe in murine and human glomerular diseases.The Journal of Clinical Investigation Dec 2023The progression of proteinuric kidney diseases is associated with podocyte loss, but the mechanisms underlying this process remain unclear. Podocytes reenter the cell...
The progression of proteinuric kidney diseases is associated with podocyte loss, but the mechanisms underlying this process remain unclear. Podocytes reenter the cell cycle to repair double-stranded DNA breaks. However, unsuccessful repair can result in podocytes crossing the G1/S checkpoint and undergoing abortive cytokinesis. In this study, we identified Pfn1 as indispensable in maintaining glomerular integrity - its tissue-specific loss in mouse podocytes resulted in severe proteinuria and kidney failure. Our results suggest that this phenotype is due to podocyte mitotic catastrophe (MC), characterized histologically and ultrastructurally by abundant multinucleated cells, irregular nuclei, and mitotic spindles. Podocyte cell cycle reentry was identified using FUCCI2aR mice, and we observed altered expression of cell-cycle associated proteins, such as p21, p53, cyclin B1, and cyclin D1. Podocyte-specific translating ribosome affinity purification and RNA-Seq revealed the downregulation of ribosomal RNA-processing 8 (Rrp8). Overexpression of Rrp8 in Pfn1-KO podocytes partially rescued the phenotype in vitro. Clinical and ultrastructural tomographic analysis of patients with diverse proteinuric kidney diseases further validated the presence of MC podocytes and reduction in podocyte PFN1 expression within kidney tissues. These results suggest that profilin1 is essential in regulating the podocyte cell cycle and its disruption leads to MC and subsequent podocyte loss.
Topics: Animals; Humans; Mice; Cell Cycle Proteins; Cell Death; Kidney Diseases; Kidney Glomerulus; Podocytes; Profilins; Proteinuria
PubMed: 37847555
DOI: 10.1172/JCI171237 -
Kidney360 Mar 2022
Topics: Biomarkers; Humans; Kidney Glomerulus; Podocytes; Renal Insufficiency, Chronic; Urinary Tract
PubMed: 35582191
DOI: 10.34067/KID.0008212021 -
Kidney International Jul 2023The biology and diversity of glomerular parietal epithelial cells (PECs) are important for understanding podocyte regeneration and crescent formation. Although protein...
The biology and diversity of glomerular parietal epithelial cells (PECs) are important for understanding podocyte regeneration and crescent formation. Although protein markers have revealed the morphological heterogeneity of PECs, the molecular characteristics of PEC subpopulations remain largely unknown. Here, we performed a comprehensive analysis of PECs using single-cell RNA sequencing (scRNA-seq) data. Our analysis identified five distinct PEC subpopulations: PEC-A1, PEC-A2, PEC-A3, PEC-A4 and PEC-B. Among these subpopulations, PEC- A1 and PEC-A2 were characterized as podocyte progenitors while PEC-A4 represented tubular progenitors. Further dynamic signaling network analysis indicated that activation of PEC-A4 and the proliferation of PEC-A3 played pivotal roles in crescent formation. Analyses suggested that upstream signals released by podocytes, immune cells, endothelial cells and mesangial cells serve as pathogenic signals and may be promising intervention targets in crescentic glomerulonephritis. Pharmacological blockade of two such pathogenic signaling targets, proteins Mif and Csf1r, reduced hyperplasia of the PECs and crescent formation in anti-glomerular basement membrane glomerulonephritis murine models. Thus, our study demonstrates that scRNA-seq-based analysis provided valuable insights into the pathology and therapeutic strategies for crescentic glomerulonephritis.
Topics: Mice; Animals; Endothelial Cells; Epithelial Cells; Kidney Glomerulus; Podocytes; Glomerulonephritis; Proteins; Kidney Diseases
PubMed: 37100348
DOI: 10.1016/j.kint.2023.03.036 -
Molecular Therapy : the Journal of the... Aug 2022Although tissue-resident-memory T (T) cells, a recently identified non-circulating memory T cell population, play a crucial role in mediating local immune responses and...
Although tissue-resident-memory T (T) cells, a recently identified non-circulating memory T cell population, play a crucial role in mediating local immune responses and protect against pathogens upon local reinfection, the composition, effector function, and specificity of T cells in the kidney and their relevance for chronic kidney disease remain unknown. In this study, we found that renal tissue displayed high abundance of tissue-resident lymphocytes, and the proportion of CD8 T cells was significantly increased in the kidney from patients and mice with focal segmental glomerulosclerosis (FSGS), diabetic kidney disease (DKD), and lupus nephritis (LN). Mechanistically, IL-15 significantly promoted CD8 T cell formation and activation, thereby promoting podocyte injury and glomerulosclerosis. Interestingly, Sparsentan, the dual angiotensin II (Ang II) receptor and endothelin type A receptor antagonist, can also reduce T cell responses by intervening IL-15 signaling, exploring its new pharmacological functions. Mechanistically, Sparsentan inhibited Ang II or endothelin-1 (ET-1)-mediated IL-15 signaling, thereby further regulating renal CD8 T cell fates. Collectively, our studies provide direct evidence for the pivotal role of renal CD8 T cells in podocyte injury and further strengthen that targeting T cells represents a novel therapeutic strategy for patients with glomerular diseases.
Topics: Animals; CD8-Positive T-Lymphocytes; Immunologic Memory; Interleukin-15; Mice; Podocytes; Signal Transduction
PubMed: 35514086
DOI: 10.1016/j.ymthe.2022.04.024