1
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Sheng A, Liu F, Wang Q, Fu H, Mao J. The roles of TRPC6 in renal tubular disorders: a narrative review. Ren Fail 2024; 46:2376929. [PMID: 39022902 PMCID: PMC11259070 DOI: 10.1080/0886022x.2024.2376929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 07/02/2024] [Indexed: 07/20/2024] Open
Abstract
The transient receptor potential canonical 6 (TRPC6) channel, a nonselective cation channel that allows the passage of Ca2+, plays an important role in renal diseases. TRPC6 is activated by Ca2+ influx, oxidative stress, and mechanical stress. Studies have shown that in addition to glomerular diseases, TRPC6 can contribute to renal tubular disorders, such as acute kidney injury, renal interstitial fibrosis, and renal cell carcinoma (RCC). However, the tubule-specific physiological functions of TRPC6 have not yet been elucidated. Its pathophysiological role in ischemia/reperfusion (I/R) injury is debatable. Thus, TRPC6 may have dual roles in I/R injury. TRPC6 induces renal fibrosis and immune cell infiltration in a unilateral ureteral obstruction (UUO) mouse model. Additionally, TRPC6 overexpression may modify G2 phase transition, thus altering the DNA damage checkpoint, which can cause genomic instability and RCC tumorigenesis and can control the proliferation of RCC cells. This review highlights the importance of TRPC6 in various conditions of the renal tubular system. To better understand certain renal disorders and ultimately identify new therapeutic targets to improve patient care, the pathophysiology of TRPC6 must be clarified.
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Affiliation(s)
- Aiqin Sheng
- Department of Nephrology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Fei Liu
- Department of Nephrology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Qianhui Wang
- Department of Nephrology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Haidong Fu
- Department of Nephrology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, Children’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
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2
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Richfield O, Cortez R, Navar LG. Modeling the interaction between tubuloglomerular feedback and myogenic mechanisms in the control of glomerular mechanics. Front Physiol 2024; 15:1410764. [PMID: 38966231 PMCID: PMC11223525 DOI: 10.3389/fphys.2024.1410764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 05/24/2024] [Indexed: 07/06/2024] Open
Abstract
Introduction: Mechanical stresses and strains exerted on the glomerular cells have emerged as potentially influential factors in the progression of glomerular disease. Renal autoregulation, the feedback process by which the afferent arteriole changes in diameter in response to changes in blood pressure, is assumed to control glomerular mechanical stresses exerted on the glomerular capillaries. However, it is unclear how the two major mechanisms of renal autoregulation, the afferent arteriole myogenic mechanism and tubuloglomerular feedback (TGF), each contribute to the maintenance of glomerular mechanical homeostasis. Methods: In this study, we made a mathematical model of renal autoregulation and combined this model with an anatomically accurate model of glomerular blood flow and filtration, developed previously by us. We parameterized the renal autoregulation model based on data from previous literature, and we found evidence for an increased myogenic mechanism sensitivity when TGF is operant, as has been reported previously. We examined the mechanical effects of each autoregulatory mechanism (the myogenic, TGF and modified myogenic) by simulating blood flow through the glomerular capillary network with and without each mechanism operant. Results: Our model results indicate that the myogenic mechanism plays a central role in maintaining glomerular mechanical homeostasis, by providing the most protection to the glomerular capillaries. However, at higher perfusion pressures, the modulation of the myogenic mechanism sensitivity by TGF is crucial for the maintenance of glomerular mechanical homeostasis. Overall, a loss of renal autoregulation increases mechanical strain by up to twofold in the capillaries branching off the afferent arteriole. This further corroborates our previous simulation studies, that have identified glomerular capillaries nearest to the afferent arteriole as the most prone to mechanical injury in cases of disturbed glomerular hemodynamics. Discussion: Renal autoregulation is a complex process by which multiple feedback mechanisms interact to control blood flow and filtration in the glomerulus. Importantly, our study indicates that another function of renal autoregulation is control of the mechanical stresses on the glomerular cells, which indicates that loss or inhibition of renal autoregulation may have a mechanical effect that may contribute to glomerular injury in diseases such as hypertension or diabetes. This study highlights the utility of mathematical models in integrating data from previous experimental studies, estimating variables that are difficult to measure experimentally (i.e. mechanical stresses in microvascular networks) and testing hypotheses that are historically difficult or impossible to measure.
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Affiliation(s)
- Owen Richfield
- Bioinnovation PhD Program, Tulane University, New Orleans, LA, United States
| | - Ricardo Cortez
- Department of Mathematics, Tulane University, New Orleans, LA, United States
| | - L. Gabriel Navar
- Department of Physiology, Tulane School of Medicine, New Orleans, LA, United States
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3
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Haydak J, Azeloglu EU. Role of biophysics and mechanobiology in podocyte physiology. Nat Rev Nephrol 2024; 20:371-385. [PMID: 38443711 DOI: 10.1038/s41581-024-00815-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 03/07/2024]
Abstract
Podocytes form the backbone of the glomerular filtration barrier and are exposed to various mechanical forces throughout the lifetime of an individual. The highly dynamic biomechanical environment of the glomerular capillaries greatly influences the cell biology of podocytes and their pathophysiology. Throughout the past two decades, a holistic picture of podocyte cell biology has emerged, highlighting mechanobiological signalling pathways, cytoskeletal dynamics and cellular adhesion as key determinants of biomechanical resilience in podocytes. This biomechanical resilience is essential for the physiological function of podocytes, including the formation and maintenance of the glomerular filtration barrier. Podocytes integrate diverse biomechanical stimuli from their environment and adapt their biophysical properties accordingly. However, perturbations in biomechanical cues or the underlying podocyte mechanobiology can lead to glomerular dysfunction with severe clinical consequences, including proteinuria and glomerulosclerosis. As our mechanistic understanding of podocyte mechanobiology and its role in the pathogenesis of glomerular disease increases, new targets for podocyte-specific therapeutics will emerge. Treating glomerular diseases by targeting podocyte mechanobiology might improve therapeutic precision and efficacy, with potential to reduce the burden of chronic kidney disease on individuals and health-care systems alike.
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Affiliation(s)
- Jonathan Haydak
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Evren U Azeloglu
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Kliewe F, Siegerist F, Hammer E, Al-Hasani J, Amling TRJ, Hollemann JZE, Schindler M, Drenic V, Simm S, Amann K, Daniel C, Lindenmeyer M, Hecker M, Völker U, Endlich N. Zyxin is important for the stability and function of podocytes, especially during mechanical stretch. Commun Biol 2024; 7:446. [PMID: 38605154 PMCID: PMC11009394 DOI: 10.1038/s42003-024-06125-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 03/29/2024] [Indexed: 04/13/2024] Open
Abstract
Podocyte detachment due to mechanical stress is a common issue in hypertension-induced kidney disease. This study highlights the role of zyxin for podocyte stability and function. We have found that zyxin is significantly up-regulated in podocytes after mechanical stretch and relocalizes from focal adhesions to actin filaments. In zyxin knockout podocytes, we found that the loss of zyxin reduced the expression of vinculin and VASP as well as the expression of matrix proteins, such as fibronectin. This suggests that zyxin is a central player in the translation of mechanical forces in podocytes. In vivo, zyxin is highly up-regulated in patients suffering from diabetic nephropathy and in hypertensive DOCA-salt treated mice. Furthermore, zyxin loss in mice resulted in proteinuria and effacement of podocyte foot processes that was measured by super resolution microscopy. This highlights the essential role of zyxin for podocyte maintenance in vitro and in vivo, especially under mechanical stretch.
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Affiliation(s)
- Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Elke Hammer
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Jaafar Al-Hasani
- Department of Cardiovascular Physiology, Heidelberg University, Heidelberg, Germany
| | | | | | - Maximilian Schindler
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Vedran Drenic
- NIPOKA GmbH, Center of High-End Imaging, Greifswald, Germany
| | - Stefan Simm
- Institute of Bioinformatics, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Amann
- Department of Nephropathology; Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Christoph Daniel
- Department of Nephropathology; Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Maja Lindenmeyer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Markus Hecker
- Department of Cardiovascular Physiology, Heidelberg University, Heidelberg, Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
- NIPOKA GmbH, Center of High-End Imaging, Greifswald, Germany
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5
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Ogino S, Yoshikawa K, Nagase T, Mikami K, Nagase M. Roles of the mechanosensitive ion channel Piezo1 in the renal podocyte injury of experimental hypertensive nephropathy. Hypertens Res 2024; 47:747-759. [PMID: 38145990 DOI: 10.1038/s41440-023-01536-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/10/2023] [Accepted: 11/18/2023] [Indexed: 12/27/2023]
Abstract
Glomerular podocyte injury plays an essential role in proteinuria pathogenesis, a hallmark of chronic kidney disease, including hypertensive nephropathy. Although podocytes are susceptible to mechanical stimuli, their mechanotransduction pathways remain elusive. Piezo proteins, including Piezo1 and 2, are mechanosensing ion channels that mediate various biological phenomena. Although renal Piezo2 expression and its alteration in rodent dehydration and hypertension models have been reported, the role of Piezo1 in hypertensive nephropathy and podocyte injury is unclear. In this study, we examined Piezo1 expression and localization in the kidneys of control mice and in those of mice with hypertensive nephrosclerosis. Uninephrectomized, aldosterone-infused, salt-loaded mice developed hypertension, albuminuria, podocyte injury, and glomerulosclerosis. RNAscope in situ hybridization revealed that Piezo1 expression was enhanced in the podocytes, mesangial cells, and distal tubular cells of these mice compared to those of the uninephrectomized, vehicle-infused control group. Piezo1 upregulation in the glomeruli was accompanied by the induction of podocyte injury-related markers, plasminogen activator inhibitor-1 and serum/glucocorticoid regulated kinase 1. These changes were reversed by antihypertensive drug. Exposure of Piezo1-expressing cultured podocytes to mechanical stretch activated Rac1 and upregulated the above-mentioned markers, which was antagonized by the Piezo1 blocker grammostola mechanotoxin #4 (GsMTx4). Administration of Piezo1-specific agonist Yoda1 mimicked the effects of mechanical stretch, which was minimized by the Yoda1-specific inhibitor Dooku1 and Rac inhibitor. Rac1 was also activated in the above-mentioned hypertensive mice, and Rac inhibitor downregulated gene expression of podocyte injury-related markers in vivo. Our results suggest that Piezo1 plays a role in mechanical stress-induced podocyte injury.
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Affiliation(s)
- Satoyuki Ogino
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
- Department of Trauma and Critical Care Medicine, Kyorin University School of Medicine, Mitaka, Japan
| | - Kei Yoshikawa
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
- Department of Trauma and Critical Care Medicine, Kyorin University School of Medicine, Mitaka, Japan
| | - Takashi Nagase
- Kunitachi Aoyagien Tachikawa Geriatric Health Services Facility, Tachikawa, Japan
| | - Kaori Mikami
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
| | - Miki Nagase
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan.
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6
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Schindler M, Endlich N. Zebrafish as a model for podocyte research. Am J Physiol Renal Physiol 2024; 326:F369-F381. [PMID: 38205541 DOI: 10.1152/ajprenal.00335.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/25/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
Podocytes, specialized postmitotic cells, are central players in various kidney-related diseases. Zebrafish have become a valuable model system for studying podocyte biology because they are genetically easy to manipulate, transparent, and their glomerular structure is similar to that of mammals. This review provides an overview of the knowledge of podocyte biology in zebrafish larvae, with particular focus on their essential contribution to understanding the mechanisms that underlie kidney diseases as well as supporting drug development. In addition, special attention is given to advances in live-imaging techniques allowing the observation of dynamic processes, including podocyte motility, podocyte process behavior, and glomerulus maturation. The review further addresses the functional aspects of podocytes in zebrafish larvae. This includes topics such as glomerular filtration, ultrastructural analyses, and evaluation of podocyte response to nephrotoxic insults. Studies presented in this context have provided important insights into the maintenance and resistance of the glomerular filtration barrier in zebrafish larvae and explored the potential transferability of these findings to mammals such as mice, rats, and most importantly, humans. The recent ability to identify potential therapeutic targets represents a promising new way to identify drugs that could effectively treat podocyte-associated glomerulopathies in humans. In summary, this review gives an overview about the importance of zebrafish as a model for podocyte-related disease and targeted drug development. It also highlights the key role of advanced imaging techniques in transparent zebrafish larvae, improving our understanding of glomerular diseases and the significant potential for translation of these findings to humans.
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Affiliation(s)
- Maximilian Schindler
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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7
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Wang Z, Fu Y, da Silva AA, do Carmo JM, Mouton A, Omoto ACM, Li X, Sears J, Hall JE. Mitochondria-Derived Reactive Oxygen Species Contribute to Synergistic Interaction of Diabetes and Hypertension in Causing Chronic Kidney Injury. Am J Physiol Renal Physiol 2024; 326:F534-F544. [PMID: 38269408 PMCID: PMC11208021 DOI: 10.1152/ajprenal.00320.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 01/26/2024] Open
Abstract
Diabetes (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. The combination of DM and HTN significantly accelerates development of renal injury; however, the underlying mechanisms of this synergy are still poorly understood. This study assessed whether mitochondria (MT) dysfunction is essential in developing renal injury in a rat model with combined DM and HTN. Type 1 DM was induced in Wistar rats by streptozotocin (STZ). HTN was induced six weeks later by inter-renal aorta constriction between the renal arteries, so that right kidneys were exposed to HTN while left kidneys were exposed to normotension. Kidneys exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion (UAE). In contrast, kidneys exposed to DM plus 8 weeks HTN had significantly increased UAE and glomerular structural damage with reduced glomerular filtration rate. Marked increases in MT-derived reactive oxygen species (ROS) were also observed in right kidneys exposed to HTN+DM. We further tested whether treatment with MT-targeted antioxidant (MitoTEMPO) after the onset of HTN attenuates renal injury in rats with DM+HTN. Results show that kidneys in DM+AC+MitoTEMPO rats had lower UAE, less glomerular damage, and preserved MT function compared to untreated DM+AC rats. Our studies indicate that MT-derived ROS play a major role in promoting kidney dysfunction when DM is combined with HTN. Preserving MT function might be a potential therapeutic approach to halt the development of renal injury when DM coexists with HTN.
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Affiliation(s)
- Zhen Wang
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Yiling Fu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Alexandre A da Silva
- Department of Physiology and Biophysics, Mississippi Center for Obesity Research, Cardiorenal and Metabolic Diseases Research Center, University of Mississippi Medical Center, Jackson, MS, United States
| | - Jussara M do Carmo
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Alan Mouton
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Ana Carolina M Omoto
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Xuan Li
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - Jaylan Sears
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
| | - John E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, United States
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8
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‘t Hart DC, van der Vlag J, Nijenhuis T. A Putative Role for TRPC6 in Immune-Mediated Kidney Injury. Int J Mol Sci 2023; 24:16419. [PMID: 38003608 PMCID: PMC10671681 DOI: 10.3390/ijms242216419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/12/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Excessive activation of the immune system is the cause of a wide variety of renal diseases. However, the pathogenic mechanisms underlying the aberrant activation of the immune system in the kidneys often remain unknown. TRPC6, a member of the Ca2+-permeant family of TRPC channels, is important in glomerular epithelial cells or podocytes for the process of glomerular filtration. In addition, TRPC6 plays a crucial role in the development of kidney injuries by inducing podocyte injury. However, an increasing number of studies suggest that TRPC6 is also responsible for tightly regulating the immune cell functions. It remains elusive whether the role of TRPC6 in the immune system and the pathogenesis of renal inflammation are intertwined. In this review, we present an overview of the current knowledge of how TRPC6 coordinates the immune cell functions and propose the hypothesis that TRPC6 might play a pivotal role in the development of kidney injury via its role in the immune system.
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9
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Chen X, Hocher CF, Shen L, Krämer BK, Hocher B. Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench. Am J Physiol Cell Physiol 2023; 325:C661-C681. [PMID: 37519230 DOI: 10.1152/ajpcell.00177.2023] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 08/01/2023]
Abstract
Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.
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Affiliation(s)
- Xin Chen
- Department of Nephrology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Carl-Friedrich Hocher
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
- Klinik für Innere Medizin, Bundeswehrkrankenhaus Berlin, Berlin, Germany
| | - Linghong Shen
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bernhard K Krämer
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Berthold Hocher
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
- Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China
- Institute of Reproductive and Stem Cell Engineering, NHC Key Laboratory of Human Stem Cell and Reproductive Engineering, School of Basic Medical Science, Central South University, Changsha, China
- IMD Institut für Medizinische Diagnostik Berlin-Potsdam GbR, Berlin, Germany
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10
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Jiang S, Alisafaei F, Huang YY, Hong Y, Peng X, Qu C, Puapatanakul P, Jain S, Miner JH, Genin GM, Suleiman HY. An ex vivo culture model of kidney podocyte injury reveals mechanosensitive, synaptopodin-templating, sarcomere-like structures. SCIENCE ADVANCES 2022; 8:eabn6027. [PMID: 36044576 PMCID: PMC9432837 DOI: 10.1126/sciadv.abn6027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Chronic kidney diseases are widespread and incurable. The biophysical mechanisms underlying them are unclear, in part because material systems for reconstituting the microenvironment of relevant kidney cells are limited. A critical question is how kidney podocytes (glomerular epithelial cells) regenerate foot processes of the filtration apparatus following injury. Recently identified sarcomere-like structures (SLSs) with periodically spaced myosin IIA and synaptopodin appear in injured podocytes in vivo. We hypothesized that SLSs template synaptopodin in the initial stages of recovery in response to microenvironmental stimuli and tested this hypothesis by developing an ex vivo culture system that allows control of the podocyte microenvironment. Results supported our hypothesis. SLSs in podocytes that migrated from isolated kidney glomeruli presented periodic synaptopodin-positive clusters that nucleated peripheral, foot process-like extensions. SLSs were mechanoresponsive to actomyosin inhibitors and substrate stiffness. Results suggest SLSs as mechanobiological mediators of podocyte recovery and as potential targets for therapeutic intervention.
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Affiliation(s)
- Shumeng Jiang
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Farid Alisafaei
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Yin-Yuan Huang
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Yuan Hong
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Xiangjun Peng
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Chengqing Qu
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Pongpratch Puapatanakul
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Sanjay Jain
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Guy M. Genin
- NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, USA
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Hani Y. Suleiman
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
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12
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Mechanisms of podocyte injury and implications for diabetic nephropathy. Clin Sci (Lond) 2022; 136:493-520. [PMID: 35415751 PMCID: PMC9008595 DOI: 10.1042/cs20210625] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 02/25/2022] [Accepted: 03/25/2022] [Indexed: 02/06/2023]
Abstract
Albuminuria is the hallmark of both primary and secondary proteinuric glomerulopathies, including focal segmental glomerulosclerosis (FSGS), obesity-related nephropathy, and diabetic nephropathy (DN). Moreover, albuminuria is an important feature of all chronic kidney diseases (CKDs). Podocytes play a key role in maintaining the permselectivity of the glomerular filtration barrier (GFB) and injury of the podocyte, leading to foot process (FP) effacement and podocyte loss, the unifying underlying mechanism of proteinuric glomerulopathies. The metabolic insult of hyperglycemia is of paramount importance in the pathogenesis of DN, while insults leading to podocyte damage are poorly defined in other proteinuric glomerulopathies. However, shared mechanisms of podocyte damage have been identified. Herein, we will review the role of haemodynamic and oxidative stress, inflammation, lipotoxicity, endocannabinoid (EC) hypertone, and both mitochondrial and autophagic dysfunction in the pathogenesis of the podocyte damage, focussing particularly on their role in the pathogenesis of DN. Gaining a better insight into the mechanisms of podocyte injury may provide novel targets for treatment. Moreover, novel strategies for boosting podocyte repair may open the way to podocyte regenerative medicine.
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Sharma M, Singh V, Sharma R, Koul A, McCarthy ET, Savin VJ, Joshi T, Srivastava T. Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease. Biomedicines 2022; 10:407. [PMID: 35203616 PMCID: PMC8962328 DOI: 10.3390/biomedicines10020407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 01/31/2022] [Accepted: 02/04/2022] [Indexed: 02/04/2023] Open
Abstract
Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.
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Affiliation(s)
- Mukut Sharma
- Research and Development Service, Kansas City VA Medical Center, Kansas City, MO 64128, USA;
- Midwest Veterans’ Biomedical Research Foundation, Kansas City, MO 64128, USA; (A.K.); (V.J.S.); (T.S.)
- Department of Internal Medicine, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, MO 66160, USA;
| | - Vikas Singh
- Neurology, Kansas City VA Medical Center, Kansas City, MO 64128, USA;
| | - Ram Sharma
- Research and Development Service, Kansas City VA Medical Center, Kansas City, MO 64128, USA;
| | - Arnav Koul
- Midwest Veterans’ Biomedical Research Foundation, Kansas City, MO 64128, USA; (A.K.); (V.J.S.); (T.S.)
| | - Ellen T. McCarthy
- Department of Internal Medicine, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, MO 66160, USA;
| | - Virginia J. Savin
- Midwest Veterans’ Biomedical Research Foundation, Kansas City, MO 64128, USA; (A.K.); (V.J.S.); (T.S.)
| | - Trupti Joshi
- Department of Health Management and Informatics, University of Missouri, Columbia, MO 65201, USA;
| | - Tarak Srivastava
- Midwest Veterans’ Biomedical Research Foundation, Kansas City, MO 64128, USA; (A.K.); (V.J.S.); (T.S.)
- Section of Nephrology, Children’s Mercy Hospital and University of Missouri, Kansas City, MO 64108, USA
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, MO 64108, USA
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14
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Wang Z, Fu Y, do Carmo JM, da Silva AA, Li X, Mouton A, Omoto ACM, Sears J, Hall JE. Transient receptor potential cation channel 6 contributes to kidney injury induced by diabetes and hypertension. Am J Physiol Renal Physiol 2022; 322:F76-F88. [PMID: 34866402 PMCID: PMC8742740 DOI: 10.1152/ajprenal.00296.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 01/03/2023] Open
Abstract
Diabetes mellitus (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. In this study, we assessed whether DM and HTN interact synergistically to promote kidney dysfunction and whether transient receptor potential cation channel 6 (TRPC6) contributes to this synergism. In wild-type (WT; B6/129s background) and TRPC6 knockout (KO) mice, DM was induced by streptozotocin injection to increase fasting glucose levels to 250-350 mg/dL. HTN was induced by aorta constriction (AC) between the renal arteries. AC increased blood pressure (BP) by ∼25 mmHg in the right kidney (above AC), whereas BP in the left kidney (below AC) returned to near normal after 8 wk, with both kidneys exposed to the same levels of blood glucose, circulating hormones, and neural influences. Kidneys of WT mice exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion. In contrast, WT kidneys exposed to DM plus HTN (WT-DM + AC mice) for 8 wk had much greater increases in albumin excretion and histological injury. Marked increased apoptosis was also observed in the right kidneys of WT-DM + AC mice. In contrast, in TRPC6 KO mice with DM + AC, right kidneys exposed to the same levels of high BP and high glucose had lower albumin excretion and less glomerular damage and apoptotic cell injury compared with right kidneys of WT-DM + AC mice. Our results suggest that TRPC6 may contribute to the interaction of DM and HTN to promote kidney dysfunction and apoptotic cell injury.NEW & NOTEWORTHY A major new finding of this study is that the combination of moderate diabetes and hypertension promoted marked renal dysfunction, albuminuria, and apoptotic cell injury, and that these effects were greatly ameliorated by transient receptor potential cation channel 6 deficiency. These results suggest that transient receptor potential cation channel 6 may play an important role in contributing to the interaction of diabetes and hypertension to promote kidney injury.
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MESH Headings
- Albuminuria/metabolism
- Albuminuria/pathology
- Albuminuria/physiopathology
- Animals
- Apoptosis
- Blood Glucose/metabolism
- Blood Pressure
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/physiopathology
- Female
- Glomerular Filtration Rate
- Hypertension/complications
- Hypertension/metabolism
- Kidney/metabolism
- Kidney/pathology
- Kidney/physiopathology
- Male
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Renal Insufficiency, Chronic/etiology
- Renal Insufficiency, Chronic/metabolism
- Renal Insufficiency, Chronic/pathology
- Renal Insufficiency, Chronic/physiopathology
- Risk Factors
- TRPC6 Cation Channel/genetics
- TRPC6 Cation Channel/metabolism
- Mice
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Affiliation(s)
- Zhen Wang
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Yiling Fu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Jussara M do Carmo
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Alexandre A da Silva
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Xuan Li
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Alan Mouton
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Ana Carolina M Omoto
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - Jaylan Sears
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
| | - John E Hall
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
- Mississippi Center for Obesity Research, University of Mississippi Medical Center, Jackson, Mississippi
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15
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Höhfeld J, Benzing T, Bloch W, Fürst DO, Gehlert S, Hesse M, Hoffmann B, Hoppe T, Huesgen PF, Köhn M, Kolanus W, Merkel R, Niessen CM, Pokrzywa W, Rinschen MM, Wachten D, Warscheid B. Maintaining proteostasis under mechanical stress. EMBO Rep 2021; 22:e52507. [PMID: 34309183 PMCID: PMC8339670 DOI: 10.15252/embr.202152507] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 06/28/2021] [Accepted: 07/01/2021] [Indexed: 12/11/2022] Open
Abstract
Cell survival, tissue integrity and organismal health depend on the ability to maintain functional protein networks even under conditions that threaten protein integrity. Protection against such stress conditions involves the adaptation of folding and degradation machineries, which help to preserve the protein network by facilitating the refolding or disposal of damaged proteins. In multicellular organisms, cells are permanently exposed to stress resulting from mechanical forces. Yet, for long time mechanical stress was not recognized as a primary stressor that perturbs protein structure and threatens proteome integrity. The identification and characterization of protein folding and degradation systems, which handle force-unfolded proteins, marks a turning point in this regard. It has become apparent that mechanical stress protection operates during cell differentiation, adhesion and migration and is essential for maintaining tissues such as skeletal muscle, heart and kidney as well as the immune system. Here, we provide an overview of recent advances in our understanding of mechanical stress protection.
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Affiliation(s)
- Jörg Höhfeld
- Institute for Cell BiologyRheinische Friedrich‐Wilhelms University BonnBonnGermany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne (CMMC)University of CologneCologneGermany
| | - Wilhelm Bloch
- Institute of Cardiovascular Research and Sports MedicineGerman Sport UniversityCologneGermany
| | - Dieter O Fürst
- Institute for Cell BiologyRheinische Friedrich‐Wilhelms University BonnBonnGermany
| | - Sebastian Gehlert
- Institute of Cardiovascular Research and Sports MedicineGerman Sport UniversityCologneGermany
- Department for the Biosciences of SportsInstitute of Sports ScienceUniversity of HildesheimHildesheimGermany
| | - Michael Hesse
- Institute of Physiology I, Life & Brain CenterMedical FacultyRheinische Friedrich‐Wilhelms UniversityBonnGermany
| | - Bernd Hoffmann
- Institute of Biological Information Processing, IBI‐2: MechanobiologyForschungszentrum JülichJülichGermany
| | - Thorsten Hoppe
- Institute for GeneticsCologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD) and CMMCUniversity of CologneCologneGermany
| | - Pitter F Huesgen
- Central Institute for Engineering, Electronics and Analytics, ZEA3Forschungszentrum JülichJülichGermany
- CECADUniversity of CologneCologneGermany
| | - Maja Köhn
- Institute of Biology IIIFaculty of Biology, and Signalling Research Centres BIOSS and CIBSSAlbert‐Ludwigs‐University FreiburgFreiburgGermany
| | - Waldemar Kolanus
- LIMES‐InstituteRheinische Friedrich‐Wilhelms University BonnBonnGermany
| | - Rudolf Merkel
- Institute of Biological Information Processing, IBI‐2: MechanobiologyForschungszentrum JülichJülichGermany
| | - Carien M Niessen
- Department of Dermatology and CECADUniversity of CologneCologneGermany
| | | | - Markus M Rinschen
- Department of Biomedicine and Aarhus Institute of Advanced StudiesAarhus UniversityAarhusDenmark
- Department of MedicineUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Dagmar Wachten
- Institute of Innate ImmunityUniversity Hospital BonnBonnGermany
| | - Bettina Warscheid
- Institute of Biology IIFaculty of Biology, and Signalling Research Centres BIOSS and CIBSSAlbert‐Ludwigs‐University FreiburgFreiburgGermany
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16
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Bellucci L, Montini G, Collino F, Bussolati B. Mesenchymal Stromal Cell-Derived Extracellular Vesicles Pass through the Filtration Barrier and Protect Podocytes in a 3D Glomerular Model under Continuous Perfusion. Tissue Eng Regen Med 2021; 18:549-560. [PMID: 34313970 PMCID: PMC8325748 DOI: 10.1007/s13770-021-00374-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 06/30/2021] [Accepted: 07/07/2021] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Dynamic cultures, characterized by continuous fluid reperfusion, elicit physiological responses from cultured cells. Mesenchymal stem cell-derived EVs (MSC-EVs) has been proposed as a novel approach in treating several renal diseases, including acute glomerular damage, by using traditional two-dimensional cell cultures and in vivo models. We here aimed to use a fluidic three-dimensional (3D) glomerular model to study the EV dynamics within the glomerular structure under perfusion. METHODS To this end, we set up a 3D glomerular model culturing human glomerular endothelial cells and podocytes inside a bioreactor on the opposite sides of a porous membrane coated with type IV collagen. The bioreactor was connected to a circuit that allowed fluid passage at the rate of 80 µl/min. To mimic glomerular damage, the system was subjected to doxorubicin administration in the presence of therapeutic MSC-EVs. RESULTS The integrity of the glomerular basal membrane in the 3D glomerulus was assessed by a permeability assay, demonstrating that the co-culture could limit the passage of albumin through the filtration barrier. In dynamic conditions, serum EVs engineered with cel-miR-39 passed through the glomerular barrier and transferred the exogenous microRNA to podocyte cell lines. Doxorubicin treatment increased podocyte apoptosis, whereas MSC-EV within the endothelial circuit protected podocytes from damage, decreasing cell death and albumin permeability. CONCLUSION Using an innovative millifluidic model, able to mimic the human glomerular barrier, we were able to trace the EV passage and therapeutic effect in dynamic conditions.
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Affiliation(s)
- Linda Bellucci
- Department of Molecular Biotechnology and Health Sciences, University of Torino, via Nizza 52, 10126, Turin, Italy
- Laboratory of Translational Research in Paediatric Nephro-Urology, Fondazione Ca' Granda IRCCS Ospedale Maggiore Policlinico, Milan, Italy
| | - Giovanni Montini
- Laboratory of Translational Research in Paediatric Nephro-Urology, Fondazione Ca' Granda IRCCS Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milano, Milan, Italy
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione Ca' Granda IRCCS, Policlinico Di Milano, Milan, Italy
| | - Federica Collino
- Laboratory of Translational Research in Paediatric Nephro-Urology, Fondazione Ca' Granda IRCCS Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milano, Milan, Italy
| | - Benedetta Bussolati
- Department of Molecular Biotechnology and Health Sciences, University of Torino, via Nizza 52, 10126, Turin, Italy.
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17
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Butt L, Unnersjö-Jess D, Höhne M, Schermer B, Edwards A, Benzing T. A mathematical estimation of the physical forces driving podocyte detachment. Kidney Int 2021; 100:1054-1062. [PMID: 34332959 DOI: 10.1016/j.kint.2021.06.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 05/27/2021] [Accepted: 06/18/2021] [Indexed: 01/21/2023]
Abstract
Loss of podocytes, possibly through the detachment of viable cells, is a hallmark of progressive glomerular disease. Podocytes are exposed to considerable physical forces due to pressure and flow resulting in circumferential wall stress and tangential shear stress exerted on the podocyte cell body, which have been proposed to contribute to podocyte depletion. However, estimations of in vivo alterations of physical forces in glomerular disease have been hampered by a lack of quantitative functional and morphological data. Here, we used ultra-resolution data and computational analyses in a mouse model of human disease, hereditary late-onset focal segmental glomerular sclerosis, to calculate increased mechanical stress upon podocyte injury. Transversal shear stress on the lateral walls of the foot processes was prominently increased during the initial stages of podocyte detachment. Thus, our study highlights the importance of targeting glomerular hemodynamics to treat glomerular disease.
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Affiliation(s)
- Linus Butt
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - David Unnersjö-Jess
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Aurelie Edwards
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; CECAD, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
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18
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Greiten JK, Kliewe F, Schnarre A, Artelt N, Schröder S, Rogge H, Amann K, Daniel C, Lindenmeyer MT, Cohen CD, Endlich K, Endlich N. The role of filamins in mechanically stressed podocytes. FASEB J 2021; 35:e21560. [PMID: 33860543 DOI: 10.1096/fj.202001179rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 02/26/2021] [Accepted: 03/15/2021] [Indexed: 11/11/2022]
Abstract
Glomerular hypertension induces mechanical load to podocytes, often resulting in podocyte detachment and the development of glomerulosclerosis. Although it is well known that podocytes are mechanosensitive, the mechanosensors and mechanotransducers are still unknown. Since filamin A, an actin-binding protein, is already described to be a mechanosensor and mechanotransducer, we hypothesized that filamins could be important for the outside-in signaling as well as the actin cytoskeleton of podocytes under mechanical stress. In this study, we demonstrate that filamin A is the main isoform of the filamin family that is expressed in cultured podocytes. Together with filamin B, filamin A was significantly up-regulated during mechanical stretch (3 days, 0.5 Hz, and 5% extension). To study the role of filamin A in cultured podocytes under mechanical stress, filamin A was knocked down (Flna KD) by specific siRNA. Additionally, we established a filamin A knockout podocyte cell line (Flna KO) by CRISPR/Cas9. Knockdown and knockout of filamin A influenced the expression of synaptopodin, a podocyte-specific protein, focal adhesions as well as the morphology of the actin cytoskeleton. Moreover, the cell motility of Flna KO podocytes was significantly increased. Since the knockout of filamin A has had no effect on cell adhesion of podocytes during mechanical stress, we simultaneously knocked down the expression of filamin A and B. Thereby, we observed a significant loss of podocytes during mechanical stress indicating a compensatory mechanism. Analyzing hypertensive mice kidneys as well as biopsies of patients suffering from diabetic nephropathy, we found an up-regulation of filamin A in podocytes in contrast to the control. In summary, filamin A and B mediate matrix-actin cytoskeleton interactions which are essential for the adaptation of cultured podocyte to mechanical stress.
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Affiliation(s)
- Jonas K Greiten
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Annabel Schnarre
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nadine Artelt
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Sindy Schröder
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Henrik Rogge
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Christoph Daniel
- Department of Nephropathology, Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Maja T Lindenmeyer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Clemens D Cohen
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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19
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Richfield O, Cortez R, Navar LG. Simulations of increased glomerular capillary wall strain in the 5/6-nephrectomized rat. Microcirculation 2021; 28:e12721. [PMID: 34192389 PMCID: PMC9285434 DOI: 10.1111/micc.12721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/27/2021] [Accepted: 06/22/2021] [Indexed: 12/21/2022]
Abstract
Objective Chronic glomerular hypertension is associated with glomerular injury and sclerosis; however, the mechanism by which increases in pressure damage glomerular podocytes remains unclear. We tested the hypothesis that increases in glomerular pressure may deleteriously affect podocyte structural integrity by increasing the strain of the glomerular capillary walls, and that glomerular capillary wall strain may play a significant role in the perpetuation of glomerular injury in disease states that are associated with glomerular hypertension. Methods We developed an anatomically accurate mathematical model of a compliant, filtering rat glomerulus to quantify the strain of the glomerular capillary walls in a remnant glomerulus of the 5/6‐nephrectomized rat model of chronic kidney disease. In terms of estimating the mechanical stresses and strains in the glomerular capillaries, this mathematical model is a substantial improvement over previous models which do not consider pressure‐induced alterations in glomerular capillary diameters in distributing plasma and erythrocytes throughout the network. Results Using previously reported data from experiments measuring the change of glomerular volume as a function of perfusion pressure, we estimated the Young's modulus of the glomerular capillary walls in both control and 5/6‐nephrectomized conditions. We found that in 5/6‐nephrectomized conditions, the Young's modulus increased to 8.6 MPa from 7.8 MPa in control conditions, but the compliance of the capillaries increased in 5/6‐nephrectomized conditions due to a 23.3% increase in the baseline glomerular capillary diameters. We found that glomerular capillary wall strain was increased approximately threefold in 5/6‐nephrectomized conditions over control, which may deleteriously affect both mesangial cells and podocytes. The magnitudes of strain in model simulations of 5/6‐nephrectomized conditions were consistent with magnitudes of strain that elicit podocyte hypertrophy and actin cytoskeleton reorganization in vitro. Conclusions Our findings indicate that glomerular capillary wall strain may deleteriously affect podocytes directly, as well as act in concert with other mechanical changes and environmental factors inherent to the in vivo setting to potentiate glomerular injury in severe renoprival conditions.
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Affiliation(s)
- Owen Richfield
- Bioinnovation PhD Program, Tulane University, New Orleans, LA, USA.,Department of Physiology, Tulane School of Medicine, New Orleans, LA, USA
| | - Ricardo Cortez
- Department of Mathematics, Tulane University, New Orleans, LA, USA
| | - L Gabriel Navar
- Department of Physiology, Tulane School of Medicine, New Orleans, LA, USA
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20
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Mima A. Sodium-Glucose Cotransporter 2 Inhibitors in Patients with Non-Diabetic Chronic Kidney Disease. Adv Ther 2021; 38:2201-2212. [PMID: 33860925 DOI: 10.1007/s12325-021-01735-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/27/2021] [Indexed: 01/08/2023]
Abstract
BACKGROUND Sodium-glucose cotransporter 2 (SGLT2) inhibitors can reduce cardiovascular morbidity and mortality in patients with type 2 diabetes. Furthermore, recent clinical studies have revealed that SGLT2 inhibitors decrease the risk of renal function impairment in patients with type 2 diabetes. However, the effects of SGLT2 inhibitors on non-diabetic chronic kidney disease (CKD) remains unclear. Regarding long-term clinical outcomes, the Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF) trial explicitly showed improvements in cardiovascular outcomes in patients presenting with heart failure, even in the absence of diabetes. The reduction in heart failure in patients without diabetes was confirmed following empagliflozin administration in the EMPagliflozin outcomE tRial in patients with chrOnic heart failure with Reduced ejection fraction (EMPEROR-Reduced) trial. A recent systematic review and meta-analysis of DAPA-HF and EMPEROR-Reduced showed improvements in the composite renal endpoint regardless of the presence of diabetes or baseline estimated glomerular filtration rate. The Dapagliflozin and Prevention of Adverse outcomes in Chronic Kidney Disease (DAPA-CKD) trial evaluated patients with CKD with or without type 2 diabetes, irrespective of whether SGLT2 inhibitor dapagliflozin was added for renin-angiotensin system blockade as background renoprotective therapy. In this trial, dapagliflozin reduced the hazard ratio for a composite renal and cardiovascular death endpoint in patients with CKD attributed to various causes, with or without type 2 diabetes.
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21
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Kozyrina AN, Piskova T, Di Russo J. Mechanobiology of Epithelia From the Perspective of Extracellular Matrix Heterogeneity. Front Bioeng Biotechnol 2020; 8:596599. [PMID: 33330427 PMCID: PMC7717998 DOI: 10.3389/fbioe.2020.596599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/06/2020] [Indexed: 11/13/2022] Open
Abstract
Understanding the complexity of the extracellular matrix (ECM) and its variability is a necessary step on the way to engineering functional (bio)materials that serve their respective purposes while relying on cell adhesion. Upon adhesion, cells receive messages which contain both biochemical and mechanical information. The main focus of mechanobiology lies in investigating the role of this mechanical coordination in regulating cellular behavior. In recent years, this focus has been additionally shifted toward cell collectives and the understanding of their behavior as a whole mechanical continuum. Collective cell phenomena very much apply to epithelia which are either simple cell-sheets or more complex three-dimensional structures. Researchers have been mostly using the organization of monolayers to observe their collective behavior in well-defined experimental setups in vitro. Nevertheless, recent studies have also reported the impact of ECM remodeling on epithelial morphogenesis in vivo. These new concepts, combined with the knowledge of ECM biochemical complexity are of key importance for engineering new interactive materials to support both epithelial remodeling and homeostasis. In this review, we summarize the structure and heterogeneity of the ECM before discussing its impact on the epithelial mechanobiology.
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Affiliation(s)
- Aleksandra N. Kozyrina
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Aachen, Germany
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Teodora Piskova
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Aachen, Germany
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Jacopo Di Russo
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Aachen, Germany
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
- DWI – Leibniz-Institute for Interactive Materials, Aachen, Germany
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22
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Ge X, Zhang T, Yu X, Muwonge AN, Anandakrishnan N, Wong NJ, Haydak JC, Reid JM, Fu J, Wong JS, Bhattacharya S, Cuttitta CM, Zhong F, Gordon RE, Salem F, Janssen W, Hone JC, Zhang A, Li H, He JC, Gusella GL, Campbell KN, Azeloglu EU. LIM-Nebulette Reinforces Podocyte Structural Integrity by Linking Actin and Vimentin Filaments. J Am Soc Nephrol 2020; 31:2372-2391. [PMID: 32737144 DOI: 10.1681/asn.2019121261] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/06/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Maintenance of the intricate interdigitating morphology of podocytes is crucial for glomerular filtration. One of the key aspects of specialized podocyte morphology is the segregation and organization of distinct cytoskeletal filaments into different subcellular components, for which the exact mechanisms remain poorly understood. METHODS Cells from rats, mice, and humans were used to describe the cytoskeletal configuration underlying podocyte structure. Screening the time-dependent proteomic changes in the rat puromycin aminonucleoside-induced nephropathy model correlated the actin-binding protein LIM-nebulette strongly with glomerular function. Single-cell RNA sequencing and immunogold labeling were used to determine Nebl expression specificity in podocytes. Automated high-content imaging, super-resolution microscopy, atomic force microscopy (AFM), live-cell imaging of calcium, and measurement of motility and adhesion dynamics characterized the physiologic role of LIM-nebulette in podocytes. RESULTS Nebl knockout mice have increased susceptibility to adriamycin-induced nephropathy and display morphologic, cytoskeletal, and focal adhesion abnormalities with altered calcium dynamics, motility, and Rho GTPase activity. LIM-nebulette expression is decreased in diabetic nephropathy and FSGS patients at both the transcript and protein level. In mice, rats, and humans, LIM-nebulette expression is localized to primary, secondary, and tertiary processes of podocytes, where it colocalizes with focal adhesions as well as with vimentin fibers. LIM-nebulette shRNA knockdown in immortalized human podocytes leads to dysregulation of vimentin filament organization and reduced cellular elasticity as measured by AFM indentation. CONCLUSIONS LIM-nebulette is a multifunctional cytoskeletal protein that is critical in the maintenance of podocyte structural integrity through active reorganization of focal adhesions, the actin cytoskeleton, and intermediate filaments.
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Affiliation(s)
- Xuhua Ge
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Tao Zhang
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Xiaoxia Yu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Alecia N Muwonge
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nanditha Anandakrishnan
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nicholas J Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jonathan C Haydak
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jordan M Reid
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jia Fu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jenny S Wong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Smiti Bhattacharya
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Mechanical Engineering, Columbia University, New York, New York
| | - Christina M Cuttitta
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fang Zhong
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Ronald E Gordon
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fadi Salem
- Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - William Janssen
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Hong Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - John C He
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - G Luca Gusella
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kirk N Campbell
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Evren U Azeloglu
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York .,Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
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Concerted EP2 and EP4 Receptor Signaling Stimulates Autocrine Prostaglandin E 2 Activation in Human Podocytes. Cells 2020; 9:cells9051256. [PMID: 32438662 PMCID: PMC7290667 DOI: 10.3390/cells9051256] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/29/2020] [Accepted: 05/14/2020] [Indexed: 12/14/2022] Open
Abstract
Glomerular hyperfiltration is an important mechanism in the development of albuminuria. During hyperfiltration, podocytes are exposed to increased fluid flow shear stress (FFSS) in Bowman’s space. Elevated Prostaglandin E2 (PGE2) synthesis and upregulated cyclooxygenase 2 (Cox2) are associated with podocyte injury by FFSS. We aimed to elucidate a PGE2 autocrine/paracrine pathway in human podocytes (hPC). We developed a modified liquid chromatography tandem mass spectrometry (LC/ESI-MS/MS) protocol to quantify cellular PGE2, 15-keto-PGE2, and 13,14-dihydro-15-keto-PGE2 levels. hPC were treated with PGE2 with or without separate or combined blockade of prostaglandin E receptors (EP), EP2, and EP4. Furthermore, the effect of FFSS on COX2, PTGER2, and PTGER4 expression in hPC was quantified. In hPC, stimulation with PGE2 led to an EP2- and EP4-dependent increase in cyclic adenosine monophosphate (cAMP) and COX2, and induced cellular PGE2. PTGER4 was downregulated after PGE2 stimulation in hPC. In the corresponding LC/ESI-MS/MS in vivo analysis at the tissue level, increased PGE2 and 15-keto-PGE2 levels were observed in isolated glomeruli obtained from a well-established rat model with glomerular hyperfiltration, the Munich Wistar Frömter rat. COX2 and PTGER2 were upregulated by FFSS. Our data thus support an autocrine/paracrine COX2/PGE2 pathway in hPC linked to concerted EP2 and EP4 signaling.
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24
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Mechanisms of Synergistic Interactions of Diabetes and Hypertension in Chronic Kidney Disease: Role of Mitochondrial Dysfunction and ER Stress. Curr Hypertens Rep 2020; 22:15. [PMID: 32016622 DOI: 10.1007/s11906-020-1016-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW To discuss the importance of synergistic interactions of diabetes mellitus (DM) and hypertension (HT) in causing chronic kidney disease and the potential molecular mechanisms involved. RECENT FINDINGS DM and HT are the two most important risk factors for chronic kidney disease (CKD) and development of end-stage renal disease (ESRD). The combination of HT and DM may synergistically promote the progression of renal injury through mechanisms that have not been fully elucidated. Hyperglycemia and other metabolic changes in DM initiate endoplasmic reticulum (ER) stress and mitochondrial (MT) adaptation in different types of glomerular cells. These adaptations appear to make the cells more vulnerable to HT-induced mechanical stress. Excessive activation of mechanosensors, possibly via transient receptor potential cation channel subfamily C member 6 (TRPC6), may lead to impaired calcium (Ca2+) homeostasis and further exacerbate ER stress and MT dysfunction promoting cellular apoptosis and glomerular injury. The synergistic effects of HT and DM to promote kidney injury may be mediated by increased intraglomerular pressure. Chronic activation of mechanotransduction signaling may amplify metabolic effects of DM causing cellular injury through a vicious cycle of impaired Ca2+ homeostasis, mitochondrial dysfunction, and ER stress.
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25
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Kliewe F, Kaling S, Lötzsch H, Artelt N, Schindler M, Rogge H, Schröder S, Scharf C, Amann K, Daniel C, Lindenmeyer MT, Cohen CD, Endlich K, Endlich N. Fibronectin is up-regulated in podocytes by mechanical stress. FASEB J 2019; 33:14450-14460. [PMID: 31675484 DOI: 10.1096/fj.201900978rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hypertension is one of the central causes of kidney damage. In the past it was shown that glomerular hypertension leads to morphologic changes of podocytes and effacement and is responsible for detachment of these postmitotic cells. Because we have shown that podocytes are mechanosensitive and respond to mechanical stress by reorganization of the actin cytoskeleton in vitro, we look for mechanotransducers in podocytes. In this study, we demonstrate that the extracellular matrix protein fibronectin (Fn1) might be a potential candidate. The present study shows that Fn1 is essential for the attachment of podocytes during mechanical stress. By real-time quantitative PCR as well as by liquid chromatography-mass spectrometry, we found a significant up-regulation of Fn1 caused by mechanical stretch (3 d, 0.5 Hz, and 5% extension). To study the role of Fn1 in cultured podocytes under mechanical stress, Fn1 was knocked down (Fn1 KD) by a specific small interfering RNA. Additionally, we established a Fn1 knockout (KO) podocyte cell line (Fn1 KO) by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9). During mechanical stress, a significant loss of podocytes (>80%) was observed in Fn1 KD as well as Fn1 KO podocytes compared with control cells. Furthermore, Fn1 KO podocytes showed a significant down-regulation of the focal adhesion proteins talin, vinculin, and paxillin and a reduced cell spreading, indicating an important role of Fn1 in adhesion. Analyses of kidney sections from patients with diabetic nephropathy have shown a significant up-regulation of FN1 in contrast to control biopsies. In summary, we show that Fn1 plays an important role in the adaptation of podocytes to mechanical stress.-Kliewe, F., Kaling, S., Lötzsch, H., Artelt, N., Schindler, M., Rogge, H., Schröder, S., Scharf, C., Amann, K., Daniel, C., Lindenmeyer, M. T., Cohen, C. D., Endlich, K., Endlich, N. Fibronectin is up-regulated in podocytes by mechanical stress.
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Affiliation(s)
- Felix Kliewe
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Sören Kaling
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Henriette Lötzsch
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Nadine Artelt
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Maximilian Schindler
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Henrik Rogge
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Sindy Schröder
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Christian Scharf
- Department of Ear, Nose, and Throat Diseases, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Amann
- Department of Nephropathology, University Medicine Erlangen, Erlangen, Germany
| | - Christoph Daniel
- Department of Nephropathology, University Medicine Erlangen, Erlangen, Germany
| | - Maja T Lindenmeyer
- III Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and
| | - Clemens D Cohen
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology University Medicine Greifswald, Greifswald, Germany
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26
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Kriz W. The Inability of Podocytes to Proliferate: Cause, Consequences, and Origin. Anat Rec (Hoboken) 2019; 303:2588-2596. [PMID: 31606944 DOI: 10.1002/ar.24291] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/07/2019] [Accepted: 08/26/2019] [Indexed: 12/24/2022]
Abstract
This study presents a theoretical analysis of the problems related to the inability of podocytes to proliferate. The basis of these problems is the very high rate of glomerular filtration. Podocytes do not in general die by apoptosis or necrosis but are lost by detachment from the glomerular basement membrane (GBM) as viable cells. Podocytes situated on the outside of the filtration barrier and attached to the GBM only by their foot processes are permanently exposed to the flow dynamic forces of the high filtration rate tending to detach them from the GBM. The major challenge seems to consist of the high shear stresses on the foot processes within the filtration slits due to filtrate flow. Healthy podocytes are able to resist this challenge, injured podocytes are not, and may undergo foot process detachment, leading to a gap in the podocyte cover of the GBM. This represents a mortal event. Like a dam break, such a leak cannot be repaired. The ongoing exposure to filtrate flow prevents any attempt to close the gap, thus preventing any regeneration including cell proliferation. An improvement of this precarious situation consists of healing by scarring that may involve only one lobule of the glomerulus, permitting the remaining lobules to maintain filtration. An answer to the question of which waste product requires such a high filtration rate for its excretion may be in the huge quantity of circulating peptides, a problem that dates far back in evolution.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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27
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Abstract
Kidney donors face a small but definite risk of end-stage renal disease 15 to 30 years postdonation. The development of proteinuria, hypertension with gradual decrease in kidney function in the donor after surgical resection of 1 kidney, has been attributed to hyperfiltration. Genetic variations, physiological adaptations, and comorbidities exacerbate the hyperfiltration-induced loss of kidney function in the years after donation. A focus on glomerular hemodynamics and capillary pressure has led to the development of drugs that target the renin-angiotensin-aldosterone system (RAAS), but these agents yield mixed results in transplant recipients and donors. Recent work on glomerular biomechanical forces highlights the differential effects of tensile stress and fluid flow shear stress (FFSS) from hyperfiltration. Capillary wall stretch due to glomerular capillary pressure increases tensile stress on podocyte foot processes that cover the capillary. In parallel, increased flow of the ultrafiltrate due to single-nephron glomerular filtration rate elevates FFSS on the podocyte cell body. Although tensile stress invokes the RAAS, FFSS predominantly activates the cyclooxygenase 2-prostaglandin E2-EP2 receptor axis. Distinguishing these 2 mechanisms is critical, as current therapeutic approaches focus on the RAAS system. A better understanding of the biomechanical forces can lead to novel therapeutic agents to target FFSS through the cyclooxygenase 2-prostaglandin E2-EP2 receptor axis in hyperfiltration-mediated injury. We present an overview of several aspects of the risk to transplant donors and discuss the relevance of FFSS in podocyte injury, loss of glomerular barrier function leading to albuminuria and gradual loss of renal function, and potential therapeutic strategies to mitigate hyperfiltration-mediated injury to the remaining kidney.
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28
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Dryer SE, Roshanravan H, Kim EY. TRPC channels: Regulation, dysregulation and contributions to chronic kidney disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1041-1066. [PMID: 30953689 DOI: 10.1016/j.bbadis.2019.04.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the gene encoding canonical transient receptor potential-6 (TRPC6) channels result in severe nephrotic syndromes that typically lead to end-stage renal disease. Many but not all of these mutations result in a gain in the function of the resulting channel protein. Since those observations were first made, substantial work has supported the hypothesis that TRPC6 channels can also contribute to progression of acquired (non-genetic) glomerular diseases, including primary and secondary FSGS, glomerulosclerosis during autoimmune glomerulonephritis, and possibly in type-1 diabetes. Their regulation has been extensively studied, especially in podocytes, but also in mesangial cells and other cell types present in the kidney. More recent evidence has implicated TRPC6 in renal fibrosis and tubulointerstitial disease caused by urinary obstruction. Consequently TRPC6 is being extensively investigated as a target for drug discovery. Other TRPC family members are present in kidney. TRPC6 can form a functional heteromultimer with TRPC3, and it has been suggested that TRPC5 may also play a role in glomerular disease progression, although the evidence on this is contradictory. Here we review literature on the expression and regulation of TRPC6, TRPC3 and TRPC5 in various cell types of the vertebrate kidney, the evidence that these channels are dysregulated in disease models, and research showing that knock-out or pharmacological inhibition of these channels can reduce the severity of kidney disease. We also summarize several areas that remain controversial, and some of the large gaps of knowledge concerning the fundamental role of these proteins in regulation of renal function.
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Affiliation(s)
- Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA; Department of Internal Medicine, Division of Nephrology, Baylor College of Medicine, Houston, TX, USA.
| | - Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
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29
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Pathophysiological and molecular mechanisms involved in renal congestion in a novel rat model. Sci Rep 2018; 8:16808. [PMID: 30429498 PMCID: PMC6235885 DOI: 10.1038/s41598-018-35162-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/29/2018] [Indexed: 01/18/2023] Open
Abstract
Increased central venous pressure in congestive heart failure causes renal dysfunction; however, the underlying mechanisms are unclear. We created a rat renal congestion model and investigated the effect of renal congestion on hemodynamics and molecular mechanisms. The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion in the left kidney only. Left kidney congestion reduced renal blood flow, glomerular filtration rate, and increased renal interstitial hydrostatic pressure. Tubulointerstitial and glomerular injury and medullary thick ascending limb hypoxia were observed only in the congestive kidneys. Molecules related to extracellular matrix expansion, tubular injury, and focal adhesion were upregulated in microarray analysis. Renal decapsulation ameliorated the tubulointerstitial injury. Electron microscopy captured pericyte detachment in the congestive kidneys. Transgelin and platelet-derived growth factor receptors, as indicators of pericyte-myofibroblast transition, were upregulated in the pericytes and the adjacent interstitium. With the compression of the peritubular capillaries and tubules, hypoxia and physical stress induce pericyte detachment, which could result in extracellular matrix expansion and tubular injury in renal congestion.
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Haley KE, Kronenberg NM, Liehm P, Elshani M, Bell C, Harrison DJ, Gather MC, Reynolds PA. Podocyte injury elicits loss and recovery of cellular forces. SCIENCE ADVANCES 2018; 4:eaap8030. [PMID: 29963620 PMCID: PMC6021140 DOI: 10.1126/sciadv.aap8030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
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.
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Affiliation(s)
- Kathryn E. Haley
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Nils M. Kronenberg
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Philipp Liehm
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Mustafa Elshani
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Cameron Bell
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
| | - David J. Harrison
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Malte C. Gather
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Paul A. Reynolds
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
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Yang X, Ding Y, Yang M, Yu L, Hu Y, Deng Y. Nestin Improves Preeclampsia-Like Symptoms by Inhibiting Activity of Cyclin-Dependent Kinase 5. Kidney Blood Press Res 2018; 43:616-627. [PMID: 29689548 DOI: 10.1159/000489146] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 04/12/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Preeclampsia (PE) is a pregnancy-specific hypertensive disorder that is characterised by a high incidence of hypertension and proteinuria. Podocytes are involved in the formation of a split membrane, which is the last barrier preventing the leakage of protein into the urine. Nestin, a cytoskeleton protein, is expressed stably in podocytes. However, the association between the Nestin concentration in urine and the progression of PE and the role of Nestin in PE remains unclear. METHODS In the present study, a mouse podocyte cell line, PE-like animal model and PE patients' urine samples were used. Eilsa kits were used to detect the levels of proteins expression in urine samples from patients and animal models. Western Blotting and immunofluorescence were used to detect proteins expression levels in cell samples and animal tissue samples. Flow cytometry was used to detect the level of apoptosis in cells. Tunel assay was used to detect the levels of apoptosis in animal tissue samples. RESULTS Nestin levels were significantly increased in PE patients than in hypertensive patients and healthy subjects, and positively correlated with proteinuria and podocalyxin. Ang II treatment decreased the expression of Nestin and Podocin in a time- and dose- dependent manner in podocytes. Restoration of the Nestin levels could reverse Ang II-induced F-actin degradation and attenuate Ang II-mediated podocyte apoptosis, while knockdown of the Nestin level exhibited the opposite. Moreover, the protective role of Nestin on podocytes is mediated by inhibition of the kinase activity of CDK5. In PE-like animal model induced by L-NAME injection, restoration of Nestin lowered the pressure and proteinuria concentration, attenuated the loss of podocytes, and decreased the expression of p35, p53 and the activity of CDK5 kinase, as compared with the control. CONCLUSIONS Our findings suggest that Nestin could improve preeclampsia-like symptoms by inhibiting the activity of CDK5, and Nestin may become a new prognostic factor and a potential therapy target for PE.
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Lee SM, Park JY, Park MS, Park JH, Park M, Yoon HJ. Association of renal hyperfiltration with incident proteinuria - A nationwide registry study. PLoS One 2018; 13:e0195784. [PMID: 29652920 PMCID: PMC5898733 DOI: 10.1371/journal.pone.0195784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/29/2018] [Indexed: 01/09/2023] Open
Abstract
To elucidate the association between renal hyperfiltration (RHF) and incident proteinuria, the data from 11,559,520 Korean adults who had undergone health screenings ≥ 3 times between 2009 and 2014 and had glomerular filtration rate (GFR) ≥60 mL/min/1.73m2 and negative dipstick test for proteinuria at baseline, were retrospectively analyzed. GFR was estimated with the Chronic Kidney Disease Epidemiology Collaboration equation based on serum creatinine, and RHF was defined as GFR >95th percentile adjusted for sex, age, body size, and diabetes and/or hypertension medication. The adjusted hazard ratio (aHR) of incident proteinuria in the RHF was 1.083 (95% CI, 1.069~1.097) compared to that of the non-RHF with Cox regression model. The association between RHF and incident proteinuria was not only in diabetic but also in non-diabetic subjects. This association was not observed in women (p for interaction <0.001). A reverse J-shaped association was found between the adjusted GFR slope and aHR of incident proteinuria. Both lower and higher GFR were associated with incident proteinuria in men. In conclusion, RHF was associated with incident proteinuria in men. Clinical studies are necessary to study whether the alleviation of RHF can prevent incident proteinuria.
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Affiliation(s)
- Seung Min Lee
- Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ju-Young Park
- Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Min-Su Park
- Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jong Heon Park
- Big Data Steering Department, National Health Insurance Service, Wonju, Gangwon, Republic of Korea
| | - Minseon Park
- Department of Family Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Hyung-Jin Yoon
- Department of Biomedical Engineering, Seoul National University College of Medicine, Seoul, Republic of Korea
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Embry AE, Liu Z, Henderson JM, Byfield FJ, Liu L, Yoon J, Wu Z, Cruz K, Moradi S, Gillombardo CB, Hussain RZ, Doelger R, Stuve O, Chang AN, Janmey PA, Bruggeman LA, Miller RT. Similar Biophysical Abnormalities in Glomeruli and Podocytes from Two Distinct Models. J Am Soc Nephrol 2018; 29:1501-1512. [PMID: 29572404 DOI: 10.1681/asn.2017050475] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 02/21/2018] [Indexed: 01/19/2023] Open
Abstract
Background FSGS is a pattern of podocyte injury that leads to loss of glomerular function. Podocytes support other podocytes and glomerular capillary structure, oppose hemodynamic forces, form the slit diaphragm, and have mechanical properties that permit these functions. However, the biophysical characteristics of glomeruli and podocytes in disease remain unclear.Methods Using microindentation, atomic force microscopy, immunofluorescence microscopy, quantitative RT-PCR, and a three-dimensional collagen gel contraction assay, we studied the biophysical and structural properties of glomeruli and podocytes in chronic (Tg26 mice [HIV protein expression]) and acute (protamine administration [cytoskeletal rearrangement]) models of podocyte injury.Results Compared with wild-type glomeruli, Tg26 glomeruli became progressively more deformable with disease progression, despite increased collagen content. Tg26 podocytes had disordered cytoskeletons, markedly abnormal focal adhesions, and weaker adhesion; they failed to respond to mechanical signals and exerted minimal traction force in three-dimensional collagen gels. Protamine treatment had similar but milder effects on glomeruli and podocytes.Conclusions Reduced structural integrity of Tg26 podocytes causes increased deformability of glomerular capillaries and limits the ability of capillaries to counter hemodynamic force, possibly leading to further podocyte injury. Loss of normal podocyte mechanical integrity could injure neighboring podocytes due to the absence of normal biophysical signals required for podocyte maintenance. The severe defects in podocyte mechanical behavior in the Tg26 model may explain why Tg26 glomeruli soften progressively, despite increased collagen deposition, and may be the basis for the rapid course of glomerular diseases associated with severe podocyte injury. In milder injury (protamine), similar processes occur but over a longer time.
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Affiliation(s)
- Addie E Embry
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhenan Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joel M Henderson
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | - F Jefferson Byfield
- Department of Physiology and Biophysics, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Liping Liu
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Medicine, Dallas Veterans Affairs Medical Center, Dallas, Texas
| | - Joonho Yoon
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhenzhen Wu
- Department of Medicine, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Katrina Cruz
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | - Sara Moradi
- Department of Pathology, Boston University School of Medicine, Boston, Massachusetts
| | | | - Rihanna Z Hussain
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Richard Doelger
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Olaf Stuve
- Department of Neurology, University of Texas Southwestern Medical School, Dallas, Texas; and
| | - Audrey N Chang
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Paul A Janmey
- Department of Physiology and Biophysics, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Leslie A Bruggeman
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - R Tyler Miller
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas; .,Department of Medicine, Dallas Veterans Affairs Medical Center, Dallas, Texas
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Kriz W, Lemley KV. Potential relevance of shear stress for slit diaphragm and podocyte function. Kidney Int 2018; 91:1283-1286. [PMID: 28501303 DOI: 10.1016/j.kint.2017.02.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/07/2017] [Accepted: 02/24/2017] [Indexed: 11/30/2022]
Abstract
Filtrate flow through the glomerular barrier produces shear stresses that tend to disconnect podocytes from the glomerular basement membrane. Forces are highest within the filtration slits. The slit diaphragm mechanically balances the lateral components of the shear stresses on opposing foot processes, preventing widening of the slit.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, Germany.
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, California, USA
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35
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Feng D, DuMontier C, Pollak MR. Mechanical challenges and cytoskeletal impairments in focal segmental glomerulosclerosis. Am J Physiol Renal Physiol 2018; 314:F921-F925. [PMID: 29363327 DOI: 10.1152/ajprenal.00641.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histologically defined form of kidney injury typically mediated by podocyte dysfunction. Podocytes rely on their intricate actin-based cytoskeleton to maintain the glomerular filtration barrier in the face of mechanical challenges resulting from pulsatile blood flow and filtration of this blood flow. This review summarizes the mechanical challenges faced by podocytes in the form of stretch and shear stress, both of which may play a role in the progression of podocyte dysfunction and detachment. It also reviews how podocytes respond to these mechanical challenges in dynamic fashion through rearranging their cytoskeleton, triggering various biochemical pathways, and, in some disease states, altering their morphology in the form of foot process effacement. Furthermore, this review highlights the growing body of evidence identifying several mutations of important cytoskeleton proteins as causes of FSGS. Lastly, it synthesizes the above evidence to show that a better understanding of how these mutations leave podocytes vulnerable to the mechanical challenges they face is essential to better understanding the mechanisms by which they lead to disease. The review concludes with future research directions to fill this gap and some novel techniques with which to pursue these directions.
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Affiliation(s)
- Di Feng
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Clark DuMontier
- Harvard Medical School , Boston, Massachusetts.,Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center , Boston, Massachusetts
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
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Srivastava T, Thiagarajan G, Alon US, Sharma R, El-Meanawy A, McCarthy ET, Savin VJ, Sharma M. Role of biomechanical forces in hyperfiltration-mediated glomerular injury in congenital anomalies of the kidney and urinary tract. Nephrol Dial Transplant 2018; 32:759-765. [PMID: 28339567 DOI: 10.1093/ndt/gfw430] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/15/2016] [Indexed: 11/13/2022] Open
Abstract
Congenital anomalies of the kidney and urinary tract (CAKUT) including solitary kidney constitute the main cause of progressive chronic kidney disease (CKD) in children. Children born with CAKUT develop signs of CKD only during adolescence and do not respond to renin-angiotensin-aldosterone system blockers. Early cellular changes underlying CKD progression to end-stage renal disease by early adulthood are not well understood. The mechanism of maladaptive hyperfiltration that occurs from loss of functional nephrons, including solitary kidney, is not clear. We re-examine the phenomenon of hyperfiltration in the context of biomechanical forces with special reference to glomerular podocytes. Capillary stretch exerts tensile stress on podocytes through the glomerular basement membrane. The flow of ultrafiltrate over the cell surface directly causes fluid flow shear stress (FFSS) on podocytes. FFSS on the podocyte surface increases 1.5- to 2-fold in animal models of solitary kidney and its effect on podocytes is a subject of ongoing research. Podocytes (i) are mechanosensitive to tensile and shear forces, (ii) use prostaglandin E2, angiotensin-II or nitric oxide for mechanoperception and (iii) use specific signaling pathways for mechanotransduction. We discuss (i) the nature of and differences in cellular responses to biomechanical forces, (ii) methods to study biomechanical forces and (iii) effects of biomechanical forces on podocytes and glomeruli. Future studies on FFSS will likely identify novel targets for strategies for early intervention to complement and strengthen the current regimen for treating children with CAKUT.
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Affiliation(s)
- Tarak Srivastava
- Section of Nephrology, Children's Mercy Hospital and University of Missouri at Kansas City, Kansas City, MO, USA.,Renal Research Laboratory, Research and Development, Kansas City VA Medical Center, Kansas City, MO, USA
| | - Ganesh Thiagarajan
- School of Computing and Engineering, University of Missouri at Kansas City, MO, USA
| | - Uri S Alon
- Section of Nephrology, Children's Mercy Hospital and University of Missouri at Kansas City, Kansas City, MO, USA
| | - Ram Sharma
- Renal Research Laboratory, Research and Development, Kansas City VA Medical Center, Kansas City, MO, USA
| | - Ashraf El-Meanawy
- Division of Nephrology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ellen T McCarthy
- Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Virginia J Savin
- Renal Research Laboratory, Research and Development, Kansas City VA Medical Center, Kansas City, MO, USA
| | - Mukut Sharma
- Renal Research Laboratory, Research and Development, Kansas City VA Medical Center, Kansas City, MO, USA
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Abu Hamad R, Berman S, Hachmo Y, Stark M, Hasan F, Doenyas-Barak K, Efrati S. Response of Renal Podocytes to Excessive Hydrostatic Pressure: a Pathophysiologic Cascade in a Malignant Hypertension Model. Kidney Blood Press Res 2017; 42:1104-1118. [PMID: 29224013 DOI: 10.1159/000485774] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 11/28/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Renal injuries induced by increased intra-glomerular pressure coincide with podocyte detachment from the glomerular basement membrane (GBM). In previous studies, it was demonstrated that mesangial cells have a crucial role in the pathogenesis of malignant hypertension. However, the exact pathophysiological cascade responsible for podocyte detachment and its relationship with mesangial cells has not been fully elucidated yet and this was the aim of the current study. METHODS Rat renal mesangial or podocytes were exposed to high hydrostatic pressure in an in-vitro model of malignant hypertension. The resulted effects on podocyte detachment, apoptosis and expression of podocin and integrinβ1 in addition to Angiotensin-II and TGF-β1 generation were evaluated. To simulate the paracrine effect podocytes were placed in mesangial cell media pre-exposed to pressure, or in media enriched with Angiotensin-II, TGF-β1 or receptor blockers. RESULTS High pressure resulted in increased Angiotensin-II levels in mesangial and podocyte cells. Angiotensin-II via the AT1 receptors reduced podocin expression and integrinβ1, culminating in detachment of both viable and apoptotic podocytes. Mesangial cells exposed to pressure had a greater increase in Angiotensin-II than pressure-exposed podocytes. The massively increased concentration of Angiotensin-II by mesangial cells, together with increased TGF-β1 production, resulted in increased apoptosis and detachment of non-viable apoptotic podocytes. Unlike the direct effect of pressure on podocytes, the mesangial mediated effects were not related to changes in adhesion proteins expression. CONCLUSIONS Hypertension induces podocyte detachment by autocrine and paracrine effects. In a direct response to pressure, podocytes increase Angiotensin-II levels. This leads, via AT1 receptors, to structural changes in adhesion proteins, culminating in viable podocyte detachment. Paracrine effects of hypertension, mediated by mesangial cells, lead to higher levels of both Angiotensin-II and TGF-β1, culminating in apoptosis and detachment of non-viable podocytes.
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Affiliation(s)
| | - Sylvia Berman
- Research & Development Unit, Zerifin, Israel.,Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | | | - Moshe Stark
- Research & Development Unit, Zerifin, Israel
| | - Fadia Hasan
- Research & Development Unit, Zerifin, Israel
| | - Keren Doenyas-Barak
- Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Shai Efrati
- Research & Development Unit, Zerifin, Israel.,Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
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38
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Abstract
Hypertensive kidney disease classically entails nephroangiosclerosis and hyalinosis with glomerular damage. However, in recent years, several evidences showed that high blood pressure also injures tubular cells, inducing epithelial-to-mesenchymal transition and tubulointerstitial fibrosis. Recently investigated mechanisms are also podocyte effacement and loss, which lead to denudation of the glomerular basement membrane and focal adhesion of the tufts to the Bowman's capsule, with reduced filtration and scars. Starting from the classic concept of nephroangiosclerosis, this review examines the recently emerged knowledge of new biochemical and molecular mechanisms underlying the kidney damage in hypertension and discusses how viable podocytes or podocyte-deriving proteins are promising tools for early diagnosis of renal remodelling in hypertension.
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39
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Bhave G, Colon S, Ferrell N. The sulfilimine cross-link of collagen IV contributes to kidney tubular basement membrane stiffness. Am J Physiol Renal Physiol 2017; 313:F596-F602. [PMID: 28424209 PMCID: PMC5625101 DOI: 10.1152/ajprenal.00096.2017] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/12/2017] [Accepted: 04/14/2017] [Indexed: 12/12/2022] Open
Abstract
Basement membranes (BMs), a specialized form of extracellular matrix, underlie nearly all cell layers and provide structural support for tissues and interact with cell surface receptors to determine cell behavior. Both macromolecular composition and stiffness of the BM influence cell-BM interactions. Collagen IV is a major constituent of the BM that forms an extensively cross-linked oligomeric network. Its deficiency leads to BM mechanical instability, as observed with glomerular BM in Alport syndrome. These findings have led to the hypothesis that collagen IV and its cross-links determine BM stiffness. A sulfilimine bond (S = N) between a methionine sulfur and a lysine nitrogen cross-links collagen IV and is formed by the matrix enzyme peroxidasin. In peroxidasin knockout mice with reduced collagen IV sulfilimine cross-links, we find a reduction in renal tubular BM stiffness. Thus this work provides the first direct experimental evidence that collagen IV sulfilimine cross-links contribute to BM mechanical properties and provides a foundation for future work on the relationship of BM mechanics to cell function in renal disease.
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Affiliation(s)
- Gautam Bhave
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
| | - Selene Colon
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Biological Sciences, Tennessee State University, Nashville, Tennessee; and
| | - Nicholas Ferrell
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee;
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40
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Kliewe F, Scharf C, Rogge H, Darm K, Lindenmeyer MT, Amann K, Cohen CD, Endlich K, Endlich N. Studying the role of fascin-1 in mechanically stressed podocytes. Sci Rep 2017; 7:9916. [PMID: 28855604 PMCID: PMC5577297 DOI: 10.1038/s41598-017-10116-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 08/04/2017] [Indexed: 11/09/2022] Open
Abstract
Glomerular hypertension causes glomerulosclerosis via the loss of podocytes, which are challenged by increased mechanical load. We have demonstrated that podocytes are mechanosensitive. However, the response of podocytes to mechanical stretching remains incompletely understood. Here we demonstrate that the actin-bundling protein fascin-1 plays an important role in podocytes that are exposed to mechanical stress. Immunofluorescence staining revealed colocalization of fascin-1 and nephrin in mouse kidney sections. In cultured mouse podocytes fascin-1 was localized along actin fibers and filopodia in stretched and unstretched podocytes. The mRNA and protein levels of fascin-1 were not affected by mechanical stress. By Western blot and 2D-gelelectrophoresis we observed that phospho-fascin-1 was significantly downregulated after mechanical stretching. It is known that phosphorylation at serine 39 (S39) regulates the bundling activity of fascin-1, e.g. required for filopodia formation. Podocytes expressing wild type GFP-fascin-1 and non-phosphorylatable GFP-fascin-1-S39A showed marked filopodia formation, being absent in podocytes expressing phosphomimetic GFP-fascin-1-S39D. Finally, the immunofluorescence signal of phosphorylated fascin-1 was strongly reduced in glomeruli of patients with diabetic nephropathy compared to healthy controls. In summary, mechanical stress dephosphorylates fascin-1 in podocytes in vitro and in vivo thereby fascin-1 may play an important role in the adaptation of podocytes to mechanical forces.
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Affiliation(s)
- Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Christian Scharf
- Department of Ear, Nose and Throat Diseases, University Medicine Greifswald, Greifswald, Germany
| | - Henrik Rogge
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Katrin Darm
- Department of Ear, Nose and Throat Diseases, University Medicine Greifswald, Greifswald, Germany
| | - Maja T Lindenmeyer
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Kerstin Amann
- Department of Nephropathology, University Medicine Erlangen, Erlangen, Germany
| | - Clemens D Cohen
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.
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41
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Affiliation(s)
- Vivette D D'Agati
- Department of Pathology, Renal Pathology Laboratory, Columbia University Medical Center, New York, New York
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42
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Endlich K, Kliewe F, Endlich N. Stressed podocytes-mechanical forces, sensors, signaling and response. Pflugers Arch 2017; 469:937-949. [PMID: 28687864 DOI: 10.1007/s00424-017-2025-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 06/22/2017] [Indexed: 02/07/2023]
Abstract
Increased glomerular capillary pressure (glomerular hypertension) and increased glomerular filtration rate (glomerular hyperfiltration) have been proven to cause glomerulosclerosis in animal models and are likely to be operative in patients. Since podocytes cover the glomerular basement membrane, they are exposed to tensile stress due to circumferential wall tension and to fluid shear stress arising from filtrate flow through the narrow filtration slits and through Bowman's space. In vitro evidence documents that podocytes respond to tensile stress as well as to fluid shear stress. Several proteins are discussed in this review that are expressed in podocytes and could act as mechanosensors converting mechanical force via a conformational change into a biochemical signal. The cation channels P2X4 and TRPC6 were shown to be involved in mechanosignaling in podocytes. P2X4 is activated by stretch-induced ATP release, while TRPC6 might be inherently mechanosensitive. Membrane, slit diaphragm and cell-matrix contact proteins are connected to the sublemmal actin network in podocytes via various linker proteins. Therefore, actin-associated proteins, like the proven mechanosensor filamin, are ideal candidates to sense forces in the podocyte cytoskeleton. Furthermore, podocytes express talin, p130Cas, and fibronectin that are known to undergo a conformational change in response to mechanical force exposing cryptic binding sites. Downstream of mechanosensors, experimental evidence suggests the involvement of MAP kinases, Ca2+ and COX2 in mechanosignaling and an emerging role of YAP/TAZ. In summary, our understanding of mechanotransduction in podocytes is still sketchy, but future progress holds promise to identify targets to alleviate conditions of increased mechanical load.
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Affiliation(s)
- Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany.
- Institut für Anatomie and Zellbiologie, Universitätsmedizin Greifswald, Friedrich-Loeffler-Str. 23c, 17489, Greifswald, Germany.
| | - Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany
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Abstract
In this article, I shall outline some of the most important aspects of the evidentiary basis of the so-called Kriz model for the development of glomerular sclerosis, a model that we continue to modify to this day. In my mind, the most important findings include the fact that podocytes are generally post-mitotic cells, so that loss of a significant number for any cause leads to podocyte insufficiency. Another pivotal finding is that in many experimental models and in human disease, podocytes detach from the GBM as living cells. These facts, together with biomechanical deduction, have led to the ongoing evolution of the original Heidelberg model.
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44
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Reiser J, Lee HW, Gupta V, Altintas MM. A High-Content Screening Technology for Quantitatively Studying Podocyte Dynamics. Adv Chronic Kidney Dis 2017; 24:183-188. [PMID: 28501082 DOI: 10.1053/j.ackd.2017.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Podocytes form the visceral layer of a kidney glomerulus and express a characteristic octopus-like cellular architecture specialized for the ultrafiltration of blood. The cytoskeletal dynamics and structural elasticity of podocytes rely on the self-organization of highly interconnected actin bundles, and the maintenance of these features is important for the intact glomerular filtration. Development of more differentiated podocytes in culture has dramatically increased our understanding of the molecular mechanisms regulating podocyte actin dynamics. Podocytes are damaged in a variety of kidney diseases, and therapies targeting podocytes are being investigated with increasing efforts. Association between podocyte damage and disease severity-or between podocyte recovery and the performance of therapeutic molecules-have been the venues of research for years. In this perspective, more standardized high--content screening has emerged as a powerful tool for visualization and analysis of podocyte morphology. This high-throughput fluorescence microscopy technique is based on an automated image analysis with simultaneous detection of various phenotypes (multiplexing) across multiple phenotypic parameters (multiparametric). Here, we review the principles of high-content screening technology and summarize efforts to carry out small compound screen using podocytes.
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45
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Kriz W, Lemley KV. Mechanical challenges to the glomerular filtration barrier: adaptations and pathway to sclerosis. Pediatr Nephrol 2017; 32:405-417. [PMID: 27008645 DOI: 10.1007/s00467-016-3358-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 11/30/2022]
Abstract
Podocytes are lost as viable cells by detachment from the glomerular basement membrane (GBM), possibly due to factors such as pressure and filtrate flow. Distension of glomerular capillaries in response to increased pressure is limited by the elastic resistance of the GBM. The endothelium and podocytes adapt to changes in GBM area. The slit diaphragm (SD) seems to adjust by shuttling SD components between the SD and the adjacent foot processes (FPs), resulting in changes in SD area that parallel those in perfusion pressure.Filtrate flow tends to drag podocytes towards the urinary orifice by shear forces, which are highest within the filtration slits. The SD represents an atypical adherens junction, mechanically interconnecting the cytoskeleton of opposing FPs and tending to balance the shear forces.If under pathological conditions, increased filtrate flows locally overtax the attachment of FPs, the SDs are replaced by occluding junctions that seal the slits and the attachment of podocytes to the GBM is reinforced by FP effacement. Failure of these temporary adaptive mechanisms results in a steady process of podocyte detachment due to uncontrolled filtrate flows through bare areas of the GBM and, subsequently, the labyrinthine subpodocyte spaces, presenting as pseudocysts. In our view, shear stress due to filtrate flow-not capillary hydrostatic pressure-is the major challenge to the attachment of podocytes to the GBM.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Ludolf-Krehl-Str. 13-17, 68167, Mannheim, Germany.
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, CA, USA
- Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
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46
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Hyperfiltration-associated biomechanical forces in glomerular injury and response: Potential role for eicosanoids. Prostaglandins Other Lipid Mediat 2017; 132:59-68. [PMID: 28108282 DOI: 10.1016/j.prostaglandins.2017.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 12/22/2016] [Accepted: 01/10/2017] [Indexed: 12/29/2022]
Abstract
Hyperfiltration is a well-known risk factor in progressive loss of renal function in chronic kidney disease (CKD) secondary to various diseases. A reduced number of functional nephrons due to congenital or acquired cause(s) results in hyperfiltration in the remnant kidney. Hyperfiltration-associated increase in biomechanical forces, namely pressure-induced tensile stress and fluid flow-induced shear stress (FFSS) determine cellular injury and response. We believe the current treatment of CKD yields limited success because it largely attenuates pressure-induced tensile stress changes but not the effect of FFSS on podocytes. Studies on glomerular podocytes, tubular epithelial cells and bone osteocytes provide evidence for a significant role of COX-2 generated PGE2 and its receptors in response to tensile stress and FFSS. Preliminary observations show increased urinary PGE2 in children born with a solitary kidney. FFSS-induced COX2-PGE2-EP2 signaling provides an opportunity to identify targets and, for developing novel agents to complement currently available treatment.
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47
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Miller RT. Mechanical properties of basement membrane in health and disease. Matrix Biol 2017; 57-58:366-373. [DOI: 10.1016/j.matbio.2016.07.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/05/2016] [Accepted: 07/07/2016] [Indexed: 01/06/2023]
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48
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Embry AE, Mohammadi H, Niu X, Liu L, Moe B, Miller-Little WA, Lu CY, Bruggeman LA, McCulloch CA, Janmey PA, Miller RT. Biochemical and Cellular Determinants of Renal Glomerular Elasticity. PLoS One 2016; 11:e0167924. [PMID: 27942003 PMCID: PMC5152842 DOI: 10.1371/journal.pone.0167924] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/22/2016] [Indexed: 12/22/2022] Open
Abstract
The elastic properties of renal glomeruli and their capillaries permit them to maintain structural integrity in the presence of variable hemodynamic forces. Measured by micro-indentation, glomeruli have an elastic modulus (E, Young's modulus) of 2.1 kPa, and estimates from glomerular perfusion studies suggest that the E of glomeruli is between 2 and 4 kPa. F-actin depolymerization by latrunculin, inhibition of acto-myosin contractility by blebbistatin, reduction in ATP synthesis, and reduction of the affinity of adhesion proteins by EDTA reduced the glomerular E to 1.26, 1.7, 1.5, and 1.43 kPa, respectively. Actin filament stabilization with jasplakinolide and increasing integrin affinity with Mg2+ increased E to 2.65 and 2.87 kPa, respectively. Alterations in glomerular E are reflected in commensurate changes in F/G actin ratios. Disruption of vimentin intermediate filaments by withaferin A reduced E to 0.92 kPa. The E of decellularized glomeruli was 0.74 kPa, indicating that cellular components of glomeruli have dominant effects on their elasticity. The E of glomerular basement membranes measured by magnetic bead displacement was 2.4 kPa. Podocytes and mesangial cells grown on substrates with E values between 3 and 5 kPa had actin fibers and focal adhesions resembling those of podocytes in vivo. Renal ischemia and ischemia-reperfusion reduced the E of glomeruli to 1.58 kPa. These results show that the E of glomeruli is between 2 and 4 kPa. E of the GBM, 2.4 kPa, is consistent with this value, and is supported by the behavior of podocytes and mesangial cells grown on variable stiffness matrices. The podocyte cytoskeleton contributes the major component to the overall E of glomeruli, and a normal E requires ATP synthesis. The reduction in glomerular E following ischemia and in other diseases indicates that reduced glomerular E is a common feature of many forms of glomerular injury and indicative of an abnormal podocyte cytoskeleton.
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Affiliation(s)
- Addie E. Embry
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - Hamid Mohammadi
- Center for Matrix Biology, University of Toronto, Toronto, Ontario, Canada
| | - Xinying Niu
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - Liping Liu
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - Borren Moe
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - William A. Miller-Little
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - Christopher Y. Lu
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
| | - Leslie A. Bruggeman
- Nephrology, MetroHealth Medical Center, Case-Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Paul A. Janmey
- Physiology and Biophysics, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - R. Tyler Miller
- Nephrology and Medicine, U.T. Southwestern Medical School, Dallas, Texas, United States of America
- Medicine, Dallas VAMC, Dallas, Texas, United States of America
- * E-mail:
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Nair M, le Roux CW, Docherty NG. Mechanisms underpinning remission of albuminuria following bariatric surgery. Curr Opin Endocrinol Diabetes Obes 2016; 23:366-72. [PMID: 27584009 DOI: 10.1097/med.0000000000000279] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW Albuminuria is a biomarker of renal injury commonly used to monitor progression of diabetic kidney disease. The appearance of excess albumin in the urine reflects alterations in the structure and permeability of the glomerular filtration barrier. The present article summarizes the clinical evidence base for remission of albuminuria after bariatric surgery. It furthermore focuses on how beneficial impacts on glomerular podocyte structure and function may explain this phenomenon. RECENT FINDINGS A coherent clinical evidence base is emerging demonstrating remission of albuminuria following bariatric surgery in patients with obesity and diabetes. The impaired metabolic milieu in diabetic kidney disease drives podocyte dedifferentiation and death through glucotoxic, lipotoxic proinflammatory, and pressure-related stress. Improvements in these parameters after surgery correlate with improvements in albuminuria and preclinical studies provide mechanistic data that support the existence of cause-effect relationship. SUMMARY The benefits of bariatric surgery extend beyond weight loss in diabetes to encompass beneficial effects on diabetic renal injury. Attenuation of the toxic metabolic milieu that the podocyte is exposed to postbariatric surgery suggests that the restitution of podocyte health is a key cellular event underpinning remission of albuminuria.
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Affiliation(s)
- Meera Nair
- aDiabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin, Dublin, IrelandbDepartment of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, SwedencInvestigative Science, Imperial College London, London, UK
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Zhou M, Zhang X, Wen X, Wu T, Wang W, Yang M, Wang J, Fang M, Lin B, Lin H. Development of a Functional Glomerulus at the Organ Level on a Chip to Mimic Hypertensive Nephropathy. Sci Rep 2016; 6:31771. [PMID: 27558173 PMCID: PMC4997336 DOI: 10.1038/srep31771] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/26/2016] [Indexed: 01/15/2023] Open
Abstract
Glomerular hypertension is an important factor exacerbating glomerular diseases to end-stage renal diseases because, ultimately, it results in glomerular sclerosis (especially in hypertensive and diabetic nephropathy). The precise mechanism of glomerular sclerosis caused by glomerular hypertension is unclear, due partly to the absence of suitable in vitro or in vivo models capable of mimicking and regulating the complex mechanical forces and/or organ-level disease processes. We developed a “glomerulus-on-a-chip” (GC) microfluidic device. This device reconstitutes the glomerulus with organ-level glomerular functions to create a disease model-on-a chip that mimics hypertensive nephropathy in humans. It comprises two channels lined by closely opposed layers of glomerular endothelial cells and podocytes that experience fluid flow of physiological conditions to mimic the glomerular microenvironment in vivo. Our results revealed that glomerular mechanical forces have a crucial role in cellular cytoskeletal rearrangement as well as the damage to cells and their junctions that leads to increased glomerular leakage observed in hypertensive nephropathy. Results also showed that the GC could readily and flexibly meet the demands of a renal-disease model. The GC could provide drug screening and toxicology testing, and create potential new personalized and accurate therapeutic platforms for glomerular disease.
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Affiliation(s)
- Mengying Zhou
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Xulang Zhang
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023, China
| | - Xinyu Wen
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Taihua Wu
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Weidong Wang
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Mingzhou Yang
- Department of Urology, Dalian Friendship Hospital, No. 8 Sanba Square, Dalian, 116001, China
| | - Jing Wang
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Ming Fang
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
| | - Bingcheng Lin
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023, China
| | - Hongli Lin
- Department of Nephrology, The First Affiliated Hospital of Dalian Medical University, Key Laboratory of Kidney Disease of Liaoning Province, The Center for the Transformation Medicine of Kidney Disease of Liaoning Province, No. 222 Zhongshan Road, Dalian 116011, China
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