1
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Huang Y, Yu M, Zheng J. Charge barriers in the kidney elimination of engineered nanoparticles. Proc Natl Acad Sci U S A 2024; 121:e2403131121. [PMID: 38805267 PMCID: PMC11161793 DOI: 10.1073/pnas.2403131121] [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: 02/13/2024] [Accepted: 04/27/2024] [Indexed: 05/30/2024] Open
Abstract
The renal elimination pathway is increasingly harnessed to reduce nonspecific accumulation of engineered nanoparticles within the body and expedite their clinical applications. While the size of nanoparticles is recognized as crucial for their passive filtration through the glomerulus due to its limited pore size, the influence of nanoparticle charge on their transport and interactions within the kidneys remains largely elusive. Herein, we report that the proximal tubule and peritubular capillary, rather than the glomerulus, serve as primary charge barriers to the transport of charged nanoparticles within the kidney. Employing a series of ultrasmall, renal-clearable gold nanoparticles (AuNPs) with precisely engineered surface charge characteristics as multimodal imaging agents, we have tracked their distribution and retention across various kidney components following intravenous administration. Our results reveal that retention in the proximal tubules is governed not by the nanoparticle's zeta-potential, but by direct Coulombic interactions between the positively charged surface ligands of the AuNPs and the negatively charged microvilli of proximal tubules. However, further enhancing these interactions leads to increased binding of the positively charged AuNPs to the peritubular capillaries during the initial phase of elimination, subsequently facilitating their slow passage through the glomeruli and interaction with tubular components in a charge-selective manner. By identifying these two critical charge-dependent barriers in the renal transport of nanoparticles, our findings offer a fundamental insight for the design of renal nanomedicines tailored for selective targeting within the kidney, laying down a foundation for developing targeting renal nanomedicines for future kidney disease management in the clinics.
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Affiliation(s)
- Yingyu Huang
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX75080
| | - Mengxiao Yu
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX75080
| | - Jie Zheng
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX75080
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2
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Yuan X, Zhao X, Wang W, Li C. Mechanosensing by Piezo1 and its implications in the kidney. Acta Physiol (Oxf) 2024; 240:e14152. [PMID: 38682304 DOI: 10.1111/apha.14152] [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: 09/21/2023] [Revised: 03/27/2024] [Accepted: 04/15/2024] [Indexed: 05/01/2024]
Abstract
Piezo1 is an essential mechanosensitive transduction ion channel in mammals. Its unique structure makes it capable of converting mechanical cues into electrical and biological signals, modulating biological and (patho)physiological processes in a wide variety of cells. There is increasing evidence demonstrating that the piezo1 channel plays a vital role in renal physiology and disease conditions. This review summarizes the current evidence on the structure and properties of Piezo1, gating modulation, and pharmacological characteristics, with special focus on the distribution and (patho)physiological significance of Piezo1 in the kidney, which may provide insights into potential treatment targets for renal diseases involving this ion channel.
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Affiliation(s)
- Xi Yuan
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xiaoduo Zhao
- Department of Pathology, The First Affiliated Hospital, Zhejiang University, Hangzhou, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Chunling Li
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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3
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Dalghi MG, DuRie E, Ruiz WG, Clayton DR, Montalbetti N, Mutchler SB, Satlin LM, Kleyman TR, Carattino MD, Shi YS, Apodaca G. Expression and localization of the mechanosensitive/osmosensitive ion channel TMEM63B in the mouse urinary tract. Physiol Rep 2024; 12:e16043. [PMID: 38724885 PMCID: PMC11082094 DOI: 10.14814/phy2.16043] [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: 03/04/2024] [Revised: 04/23/2024] [Accepted: 04/23/2024] [Indexed: 05/12/2024] Open
Abstract
The epithelial cells that line the kidneys and lower urinary tract are exposed to mechanical forces including shear stress and wall tension; however, the mechanosensors that detect and respond to these stimuli remain obscure. Candidates include the OSCA/TMEM63 family of ion channels, which can function as mechanosensors and osmosensors. Using Tmem63bHA-fl/HA-fl reporter mice, we assessed the localization of HA-tagged-TMEM63B within the urinary tract by immunofluorescence coupled with confocal microscopy. In the kidneys, HA-TMEM63B was expressed by proximal tubule epithelial cells, by the intercalated cells of the collecting duct, and by the epithelial cells lining the thick ascending limb of the medulla. In the urinary tract, HA-TMEM63B was expressed by the urothelium lining the renal pelvis, ureters, bladder, and urethra. HA-TMEM63B was also expressed in closely allied organs including the epithelial cells lining the seminal vesicles, vas deferens, and lateral prostate glands of male mice and the vaginal epithelium of female mice. Our studies reveal that TMEM63B is expressed by subsets of kidney and lower urinary tract epithelial cells, which we hypothesize are sites of TMEM63B mechanosensation or osmosensation, or both.
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Affiliation(s)
- Marianela G. Dalghi
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Ella DuRie
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Wily G. Ruiz
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Dennis R. Clayton
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Nicolas Montalbetti
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Stephanie B. Mutchler
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Lisa M. Satlin
- Department of PediatricsIcahn School of Medicine at Mount SinaiNew YorkNew YorkUSA
| | - Thomas R. Kleyman
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Chemical Biology & PharmacologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Marcelo D. Carattino
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| | - Yun Stone Shi
- Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Medical SchoolNanjing UniversityNanjingChina
| | - Gerard Apodaca
- Department of Medicine and George M. O'Brien Pittsburgh Center for Kidney ResearchUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
- Department of Cell BiologyUniversity of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
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4
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Saini S, Rani L, Shukla N, Thakur RS, Patel DK, Ansari MS, Banerjee M, Gautam NK. Hsp27 over expression protect against cadmium induced nephrotoxicity in Drosophila melanogaster. Comp Biochem Physiol C Toxicol Pharmacol 2023; 273:109716. [PMID: 37586579 DOI: 10.1016/j.cbpc.2023.109716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 07/27/2023] [Accepted: 08/13/2023] [Indexed: 08/18/2023]
Abstract
Cadmium (Cd) exposure to the animals including humans is reported as nephrotoxic compounds i.e., disturbing redox status (increase oxidative stress), mitochondrial dysfunction, renal cell death and altered transporters in the renal system. Hsp27 (a small heat shock protein) has been shown as one of the modulators in the renal dysfunction and increased against the Cd induced toxicity. However, no studies are reported on the genetic modulation of stress protein against the Cd-induced nephrotoxicity. The current study aimed to examine the protective role of hsp27 overexpression against the Cd-induced nephrotoxicity using Drosophila melanogaster as an animal model. D. melanogaster renal system includes nephrocytes and Malpighian tubules (MTs) that show the functional similarity with mammalian kidney nephron. Overexpression of the hsp27 was found to reduce the Cd induced oxidative stress, rescue cell death in MTs of Cd exposed D. melanogaster larvae. The rescued GSH level, NADPH level and glucose 6 phosphate dehydrogenase (G6PD) activity were also observed in the MTs of the Cd exposed organism. Function (efflux activity and fluid secretion rate) of the MTs was restored in Cd exposed hsp27 overexpressed larvae. Further, results were confirmed by restored brush border microvilli density and reduced uric acid level. Tissue specific knockdown of hsp27 developed Cd like phenotypes in MTs and the phenotypes enhanced in Cd exposed condition. The present study clearly shows the role of hsp27 overexpression in restoration of the MTs function and protection against the Cd induced renal toxicity.
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Affiliation(s)
- Sanjay Saini
- Department of Urology and Renal Transplantation, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226014, Uttar Pradesh, India; Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), C, Lucknow 226 001, Uttar Pradesh, India; Molecular and Human Genetics Laboratory, Department of Zoology, University of Lucknow, Lucknow 226007, India
| | - Lavi Rani
- Department of Urology and Renal Transplantation, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226014, Uttar Pradesh, India; Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), C, Lucknow 226 001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, Uttar Pradesh, India
| | - Neha Shukla
- Department of Urology and Renal Transplantation, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226014, Uttar Pradesh, India; Embryotoxicology Laboratory, Environmental Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), C, Lucknow 226 001, Uttar Pradesh, India
| | - Ravindra Singh Thakur
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, Uttar Pradesh, India; Analytical Chemistry Laboratory, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow 226001, Uttar Pradesh, India
| | - Devendra Kumar Patel
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, Uttar Pradesh, India; Analytical Chemistry Laboratory, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow 226001, Uttar Pradesh, India
| | - M S Ansari
- Department of Urology and Renal Transplantation, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
| | - Monisha Banerjee
- Molecular and Human Genetics Laboratory, Department of Zoology, University of Lucknow, Lucknow 226007, India
| | - Naveen Kumar Gautam
- Department of Urology and Renal Transplantation, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow 226014, Uttar Pradesh, India.
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5
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Sharkova M, Chow E, Erickson T, Hocking JC. The morphological and functional diversity of apical microvilli. J Anat 2023; 242:327-353. [PMID: 36281951 PMCID: PMC9919547 DOI: 10.1111/joa.13781] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/30/2022] Open
Abstract
Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Erica Chow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Timothy Erickson
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jennifer C Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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6
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Wei Y, Wang K, Xia Q, Li B, Liu L. 3D diversiform dynamic process of microvilli in living cells. Biochem Biophys Res Commun 2022; 635:114-119. [DOI: 10.1016/j.bbrc.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 09/17/2022] [Accepted: 10/01/2022] [Indexed: 11/25/2022]
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7
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Du Z, Yan Q, Shen E, Weinstein AM, Wang T. Regulation of glomerulotubular balance. IV. Implication of aquaporin 1 in flow-dependent proximal tubule transport and cell volume. Am J Physiol Renal Physiol 2022; 323:F642-F653. [PMID: 36108052 PMCID: PMC9705020 DOI: 10.1152/ajprenal.00167.2022] [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: 06/14/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022] Open
Abstract
The water channel aquaporin-1 (AQP1) is the principal water pathway for isotonic water reabsorption in the kidney proximal tubule (PT). We investigated flow-mediated fluid (Jv) and [Formula: see text] ([Formula: see text]) reabsorption in PTs of the mouse kidney by microperfusion in wild-type (WT) and AQP1 knockout (KO) mice. Experiments were simulated in an adaptation of a mathematical model of the rat PT. An increase in perfusion rate from 5 to 20 nL/min increased Jv and [Formula: see text] in PTs of WT mice. AQP1 KO mice significantly decreased Jv at low and high flow rates compared with control. In contrast, [Formula: see text] was not reduced at either low or high flow rates. Cell volume showed no significant difference between WT and AQP1 KO mice. Renal clearance experiments showed significantly higher urine flow in AQP1 KO mice, but there was no significant difference in either Na+ and K+ or [Formula: see text] excretion. Acid-base parameters of blood pH, Pco2, [Formula: see text], and urine pH were the same in both WT and KO mice. In model calculations, tubules whose tight junction (TJ) water permeability (Pf) was that assigned to the rat TJ, showed no difference in Jv between WT and KO, whereas TJ Pf set to 25% of the rat predicted Jv concordant with our observations from AQP1 KO. These results affirm the dominance of AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrate that flow-stimulated [Formula: see text] reabsorption is intact and independent of AQP1. With reference to the model, the findings also suggest that TJ water flux in the PT is less prominent in the mouse than in the rat kidney.NEW & NOTEWORTHY We found an absence of flow-dependent modulation of fluid absorption but no effect on either proximal tubule (PT) [Formula: see text] absorption or acid-base parameters in the aquaporin 1 (AQP1) knockout mouse. We affirmed the dominance of the water channel AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrated that flow-stimulated [Formula: see text] reabsorption is independent of AQP1. With reference to the model, the findings also suggest that tight junctional water flux in the PT is less prominent in the mouse than rat kidney.
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Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Qingshang Yan
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Emma Shen
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College, Cornell University, New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
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8
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Ajay AK. Functional Drug Screening using Kidney Cells On-A-Chip: Advances in Disease Modeling and Development of Biomarkers. KIDNEY360 2022; 3:194-198. [PMID: 35373124 PMCID: PMC8967633 DOI: 10.34067/kid.0007172021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 01/13/2022] [Indexed: 01/12/2023]
Affiliation(s)
- Amrendra K. Ajay
- Division of Renal Medicine, Brigham and Women’s Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
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9
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Claude-Taupin A, Codogno P, Dupont N. Links between autophagy and tissue mechanics. J Cell Sci 2021; 134:271984. [PMID: 34472605 DOI: 10.1242/jcs.258589] [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] [Indexed: 12/12/2022] Open
Abstract
Physical constraints, such as compression, shear stress, stretching and tension, play major roles during development, tissue homeostasis, immune responses and pathologies. Cells and organelles also face mechanical forces during migration and extravasation, and investigations into how mechanical forces are translated into a wide panel of biological responses, including changes in cell morphology, membrane transport, metabolism, energy production and gene expression, is a flourishing field. Recent studies demonstrate the role of macroautophagy in the integration of physical constraints. The aim of this Review is to summarize and discuss our knowledge of the role of macroautophagy in controlling a large panel of cell responses, from morphological and metabolic changes, to inflammation and senescence, for the integration of mechanical forces. Moreover, wherever possible, we also discuss the cell surface molecules and structures that sense mechanical forces upstream of macroautophagy.
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Affiliation(s)
- Aurore Claude-Taupin
- Institut Necker-Enfants Malades (INEM), INSERM U1151, CNRS UMR 8253, Université de Paris, 75015 Paris, France
| | - Patrice Codogno
- Institut Necker-Enfants Malades (INEM), INSERM U1151, CNRS UMR 8253, Université de Paris, 75015 Paris, France
| | - Nicolas Dupont
- Institut Necker-Enfants Malades (INEM), INSERM U1151, CNRS UMR 8253, Université de Paris, 75015 Paris, France
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10
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Du Z, Tian X, Ma M, Somlo S, Weinstein AM, Wang T. Restoration of proximal tubule flow-activated transport prevents cyst growth in polycystic kidney disease. JCI Insight 2021; 6:146041. [PMID: 33886508 PMCID: PMC8262298 DOI: 10.1172/jci.insight.146041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 04/21/2021] [Indexed: 01/11/2023] Open
Abstract
Flow-activated Na+ and HCO3– transport in kidney proximal tubules (PT) underlies relatively constant fractional reabsorption during changes in glomerular filtration rate (GFR) or glomerulotubular balance (GTB). In view of hypothesized connections of epithelial cilia to flow sensing, we examined flow-activated transport in 3 polycystic kidney disease–related mouse models based on inducible conditional KO of Pkd1, Pkd2, and Kif3a. PTs were harvested from mice after gene inactivation but prior to cyst formation, and flow-mediated PT transport was measured. We confirm that higher flow increased both Na+ and HCO3– absorption in control mice, and we observed that this flow effect was preserved in PTs of Pkd1–/– and Kif3a–/–mice. However, flow activation was absent in Pkd2+/– and Pkd2–/– PT. In heterozygous (Pkd2+/–) mice, a dopamine receptor 1 (DA1) antagonist (SCH23390) restored transport flow sensitivity. When given chronically, this same antagonist reduced renal cyst formation in Pkd2–/–, as evidenced by reduced kidney weight, BUN, and the cystic index, when compared with untreated mice. In contrast, SCH23390 did not prevent cyst formation in Pkd1–/– mice. These results indicate that Pkd2 is necessary for normal GTB and that restoration of flow-activated transport by DA1 antagonist can slow renal cyst formation in Pkd2–/– mice.
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Affiliation(s)
| | - Xin Tian
- Department of Internal Medicine (Nephrology), Yale University, New Haven, Connecticut, USA
| | - Ming Ma
- Department of Internal Medicine (Nephrology), Yale University, New Haven, Connecticut, USA
| | - Stefan Somlo
- Department of Internal Medicine (Nephrology), Yale University, New Haven, Connecticut, USA
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York, USA
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11
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Role of Shear Stress on Renal Proximal Tubular Cells for Nephrotoxicity Assays. J Toxicol 2021; 2021:6643324. [PMID: 33976696 PMCID: PMC8084667 DOI: 10.1155/2021/6643324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 03/24/2021] [Indexed: 12/21/2022] Open
Abstract
Drug-induced nephrotoxicity causes huge morbidity and mortality at massive financial cost. The greatest burden of drug-induced acute kidney injury falls on the proximal tubular cells. To maintain their structure and function, renal proximal tubular cells need the shear stress from tubular fluid flow. Diverse techniques to reintroduce shear stress have been studied in a variety of proximal tubular like cell culture models. These studies often have limited replicates because of the huge cost of equipment and do not report all relevant parameters to allow reproduction and comparison of studies between labs. This review codifies the techniques used to reintroduce shear stress, the cell lines utilized, and the biological outcomes reported. Further, we propose a set of interventions to enhance future cell biology understanding of nephrotoxicity using cell culture models.
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12
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Repetti R, Majumder N, De Oliveira KC, Meth J, Yangchen T, Sharma M, Srivastava T, Rohatgi R. Unilateral Nephrectomy Stimulates ERK and Is Associated With Enhanced Na Transport. Front Physiol 2021; 12:583453. [PMID: 33633581 PMCID: PMC7901926 DOI: 10.3389/fphys.2021.583453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/14/2021] [Indexed: 11/13/2022] Open
Abstract
Nephron loss initiates compensatory hemodynamic and cellular effects on the remaining nephrons. Increases in single nephron glomerular filtration rate and tubular flow rate exert higher fluid shear stress (FSS) on tubules. In principal cell (PC) culture models FSS induces ERK, and ERK is implicated in the regulation of transepithelial sodium (Na) transport, as well as, proliferation. Thus, we hypothesize that high tubular flow and FSS mediate ERK activation in the cortical collecting duct (CCD) of solitary kidney which regulates amiloride sensitive Na transport and affects CCD cell number. Immunoblotting of whole kidney protein lysate was performed to determine phospho-ERK (pERK) expression. Next, sham and unilateral nephrectomized mice were stained with anti-pERK antibodies, and dolichos biflorus agglutinin (DBA) to identify PCs with pERK. Murine PCs (mpkCCD) were grown on semi-permeable supports under static, FSS, and FSS with U0126 (a MEK1/2 inhibitor) conditions to measure the effects of FSS and ERK inhibition on amiloride sensitive Na short circuit current (Isc). pERK abundance was greater in kidney lysate of unilateral vs. sham nephrectomies. The total number of cells in CCD and pERK positive PCs increased in nephrectomized mice (9.3 ± 0.4 vs. 6.1 ± 0.2 and 5.1 ± 0.5 vs. 3.6 ± 0.3 cell per CCD nephrectomy vs. sham, respectively, n > 6 per group, p < 0.05). However, Ki67, a marker of proliferation, did not differ by immunoblot or immunohistochemistry in nephrectomy samples at 1 month compared to sham. Next, amiloride sensitive Isc in static mpkCCD cells was 25.3 ± 1.7 μA/cm2 (n = 21), but after exposure to 24 h of FSS the Isc increased to 41.4 ± 2.8 μA/cm2 (n = 22; p < 0.01) and returned to 19.1 ± 2.1 μA/cm2 (n = 18, p < 0.01) upon treatment with U0126. Though FSS did not alter α- or γ-ENaC expression in mpkCCD cells, γ-ENaC was reduced in U0126 treated cells. In conclusion, pERK increases in whole kidney and, specifically, CCD cells after nephrectomy, but pERK was not associated with active proliferation at 1-month post-nephrectomy. In vitro studies suggest high tubular flow induces ERK dependent ENaC Na absorption and may play a critical role in Na balance post-nephrectomy.
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Affiliation(s)
- Robert Repetti
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Nomrota Majumder
- School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | | | - Jennifer Meth
- Northport VA Medical Center, Northport, NY, United States
| | - Tenzin Yangchen
- Program in Public Health, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Mukut Sharma
- Kansas City VA Medical Center, Kansas City, MO, United States
| | | | - Rajeev Rohatgi
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
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13
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Kulvichit W, Wen X, Srisawat N, Pisitkun T, Smith A, Palevsky PM, Kellum JA. Urinary ezrin and moesin as novel markers for recovery from acute kidney injury. Nephrol Dial Transplant 2020; 36:938-941. [PMID: 33313829 DOI: 10.1093/ndt/gfaa328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/16/2020] [Indexed: 11/12/2022] Open
Affiliation(s)
- Win Kulvichit
- Department of Critical Care Medicine, Center for Critical Care Nephrology, CRISMA Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Excellence Center for Critical Care Nephrology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.,Faculty of Medicine, Center of Excellence in Systems Biology, Chulalongkorn University, Bangkok, Thailand
| | - Xiaoyan Wen
- Department of Critical Care Medicine, Center for Critical Care Nephrology, CRISMA Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nattachai Srisawat
- Department of Critical Care Medicine, Center for Critical Care Nephrology, CRISMA Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Excellence Center for Critical Care Nephrology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Trairak Pisitkun
- Faculty of Medicine, Center of Excellence in Systems Biology, Chulalongkorn University, Bangkok, Thailand
| | - Ali Smith
- Department of Critical Care Medicine, Center for Critical Care Nephrology, CRISMA Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Paul M Palevsky
- Department of Medicine, Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, PA, USA
| | - John A Kellum
- Department of Critical Care Medicine, Center for Critical Care Nephrology, CRISMA Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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14
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Liu X, Wei Y, Li W, Li B, Liu L. Cytoskeleton induced the changes of microvilli and mechanical properties in living cells by atomic force microscopy. J Cell Physiol 2020; 236:3725-3733. [PMID: 33169846 DOI: 10.1002/jcp.30110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/08/2020] [Accepted: 10/05/2020] [Indexed: 01/05/2023]
Abstract
The cytoskeleton acts as a scaffold for membrane protrusion, such as microvilli. However, the relationship between the characteristics of microvilli and cytoskeleton remains poorly understood under the physiological state. To investigate the role of the cytoskeleton in regulating microvilli and cellular mechanical properties, atomic force microscopy (AFM) was used to detect the dynamic characteristics of microvillus morphology and elastic modulus of living HeLa cells. First, HeLa and MCF-7 cell lines were stained with Fluor-488-phalloidin and microtubules antibody. Then, the microvilli morphology was analyzed by high-resolution images of AFM in situ. Furthermore, changes in elastic modulus were investigated by the force curve of AFM. Fluorescence microscopy and AFM results revealed that destroyed microfilaments led to a smaller microvilli size, whereas the increase in the aggregation and number of microfilaments led to a larger microvilli size. The destruction and aggregation of microfilaments remarkably affected the mechanical properties of HeLa cells. Microtubule-related drugs induced the change of microtubule, but we failed to note significant differences in microvilli morphology and mechanical properties of cells. In summary, our results unraveled the relationship between microfilaments and the structure of microvilli and Young's modulus in living HeLa cells, which would contribute to the further understanding of the physiological function of the cytoskeleton in vivo.
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Affiliation(s)
- Xueyan Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China
| | - Yuhui Wei
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
| | - Bin Li
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Lin Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
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15
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Gualdani R, Seghers F, Yerna X, Schakman O, Tajeddine N, Achouri Y, Tissir F, Devuyst O, Gailly P. Mechanical activation of TRPV4 channels controls albumin reabsorption by proximal tubule cells. Sci Signal 2020; 13:13/653/eabc6967. [DOI: 10.1126/scisignal.abc6967] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Defects in protein reabsorption by the proximal tubule are toxic for epithelial cells in the nephron and may result in nephropathy. In this study, we showed that the ion channel TRPV4 modulated the endocytosis of albumin and low–molecular weight proteins in the proximal tubule. TRPV4 was found at the basolateral side of proximal tubule cells, and its mechanical activation by cell stretching induced Ca2+ entry into the cytosol, which promoted endocytosis. Trpv4−/− mice presented with mild proximal tubule dysfunction under basal conditions. To challenge endocytic function, the permeability of the glomerular filter was altered by systemic delivery of angiotensin II. The proteinuria induced by this treatment was more severe in Trpv4−/− than in Trpv4+/+ mice. Injecting antibodies against the glomerular basement membrane to induce glomerulonephritis is a more pathophysiologically relevant method of impairing glomerular filter permeability. Albuminuria was more severe in mice that lacked TRPV4 specifically in the proximal tubule than in control mice. These results emphasize the importance of TRPV4 in sensing pressure in the proximal tubule in response to variations in the amount of ultrafiltrate and unveil a mechanism that controls protein reabsorption.
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Affiliation(s)
- Roberta Gualdani
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
| | - François Seghers
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
| | - Xavier Yerna
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
| | - Olivier Schakman
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
| | - Nicolas Tajeddine
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
| | - Younès Achouri
- Université catholique de Louvain, de Duve Institute, Transgenic Core Facility, av. Hippocrate 75/B1.75.09, B-1200 Brussels, Belgium
| | - Fadel Tissir
- Université catholique de Louvain, Institute of Neuroscience, Developmental Neurobiology, av. Hippocrate 73/B1.73.16, B-1200 Brussels, Belgium
| | - Olivier Devuyst
- University of Zurich, Institute of Physiology, Winterthurerstr. 190, CH-8057 Zurich, Switzerland
| | - Philippe Gailly
- Université catholique de Louvain, Institute of Neuroscience, Cell Physiology, av. Mounier 53/B1.53.17, B-1200 Brussels, Belgium
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16
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Miceli C, Roccio F, Penalva-Mousset L, Burtin M, Leroy C, Nemazanyy I, Kuperwasser N, Pontoglio M, Friedlander G, Morel E, Terzi F, Codogno P, Dupont N. The primary cilium and lipophagy translate mechanical forces to direct metabolic adaptation of kidney epithelial cells. Nat Cell Biol 2020; 22:1091-1102. [PMID: 32868900 DOI: 10.1038/s41556-020-0566-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 07/28/2020] [Indexed: 12/19/2022]
Abstract
Organs and cells must adapt to shear stress induced by biological fluids, but how fluid flow contributes to the execution of specific cell programs is poorly understood. Here we show that shear stress favours mitochondrial biogenesis and metabolic reprogramming to ensure energy production and cellular adaptation in kidney epithelial cells. Shear stress stimulates lipophagy, contributing to the production of fatty acids that provide mitochondrial substrates to generate ATP through β-oxidation. This flow-induced process is dependent on the primary cilia located on the apical side of epithelial cells. The interplay between fluid flow and lipid metabolism was confirmed in vivo using a unilateral ureteral obstruction mouse model. Finally, primary cilium-dependent lipophagy and mitochondrial biogenesis are required to support energy-consuming cellular processes such as glucose reabsorption, gluconeogenesis and cytoskeletal remodelling. Our findings demonstrate how primary cilia and autophagy are involved in the translation of mechanical forces into metabolic adaptation.
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Affiliation(s)
- Caterina Miceli
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France.,Center for Autophagy Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Federica Roccio
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Lucille Penalva-Mousset
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Martine Burtin
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Christine Leroy
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Ivan Nemazanyy
- Platform for Metabolic Analyses, Structure Fédérative de Recherche Necker, INSERM US24/CNRS UMS 3633, Paris, France
| | - Nicolas Kuperwasser
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Marco Pontoglio
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Gérard Friedlander
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Etienne Morel
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Fabiola Terzi
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France
| | - Patrice Codogno
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France.
| | - Nicolas Dupont
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université de Paris, Paris, France.
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17
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Verschuren EHJ, Castenmiller C, Peters DJM, Arjona FJ, Bindels RJM, Hoenderop JGJ. Sensing of tubular flow and renal electrolyte transport. Nat Rev Nephrol 2020; 16:337-351. [DOI: 10.1038/s41581-020-0259-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2020] [Indexed: 02/06/2023]
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18
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Sateesh J, Guha K, Dutta A, Sengupta P, Srinivasa Rao K. Regenerating re-absorption function of proximal convoluted tubule using microfluidics for kidney-on-chip applications. SN APPLIED SCIENCES 2019. [DOI: 10.1007/s42452-019-1840-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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19
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A systematic investigation of the effect of the fluid shear stress on Caco-2 cells towards the optimization of epithelial organ-on-chip models. Biomaterials 2019; 225:119521. [DOI: 10.1016/j.biomaterials.2019.119521] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 01/01/2023]
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20
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Vriend J, Peters JGP, Nieskens TTG, Škovroňová R, Blaimschein N, Schmidts M, Roepman R, Schirris TJJ, Russel FGM, Masereeuw R, Wilmer MJ. Flow stimulates drug transport in a human kidney proximal tubule-on-a-chip independent of primary cilia. Biochim Biophys Acta Gen Subj 2019; 1864:129433. [PMID: 31520681 DOI: 10.1016/j.bbagen.2019.129433] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Kidney disease modeling and assessment of drug-induced kidney injury can be advanced using three-dimensional (3D) microfluidic models that recapitulate in vivo characteristics. Fluid shear stress (FSS) has been depicted as main modulator improving in vitro physiology in proximal tubule epithelial cells (PTECs). We aimed to elucidate the role of FSS and primary cilia on transport activity and morphology in PTECs. METHODS Human conditionally immortalized PTEC (ciPTEC-parent) was cultured in a microfluidic 3D device, the OrganoPlate, under a physiological peak FSS of 2.0 dyne/cm2 or low peak FSS of 0.5 dyne/cm2. Upon a 9-day exposure to FSS, albumin-FITC uptake, activity of P-glycoprotein (P-gp) and multidrug resistance-associated proteins 2/4 (MRP2/4), cytotoxicity and cell morphology were determined. RESULTS A primary cilium knock-out cell model, ciPTEC-KIF3α-/-, was successfully established via CRISPR-Cas9 genome editing. Under physiological peak FSS, albumin-FITC uptake (p = .04) and P-gp efflux (p = .002) were increased as compared to low FSS. Remarkably, a higher albumin-FITC uptake (p = .03) and similar trends in activity of P-gp and MRP2/4 were observed in ciPTEC-KIF3α-/-. FSS induced cell elongation corresponding with the direction of flow in both cell models, but had no effect on cyclosporine A-induced cytotoxicity. CONCLUSIONS FSS increased albumin uptake, P-gp efflux and cell elongation, but this was not attributed to a mechanosensitive mechanism related to primary cilia in PTECs, but likely to microvilli present at the apical membrane. GENERAL SIGNIFICANCE FSS-induced improvements in biological characteristics and activity in PTECs was not mediated through a primary cilium-related mechanism.
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Affiliation(s)
- Jelle Vriend
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Janny G P Peters
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tom T G Nieskens
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Renata Škovroňová
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Nina Blaimschein
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Miriam Schmidts
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Center for Pediatrics and Adolescent Medicine, University Hospital Freiburg, Freiburg University Faculty of Medicine, Freiburg, Germany
| | - Ronald Roepman
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tom J J Schirris
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Centre for Systems Biology and Bioenergetics, Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, The Netherlands
| | - Frans G M Russel
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands; Centre for Systems Biology and Bioenergetics, Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, The Netherlands
| | - Rosalinde Masereeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands
| | - Martijn J Wilmer
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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21
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Starvation effect on the morphology of microvilli in HeLa cells. Biochem Biophys Res Commun 2019; 514:1238-1243. [DOI: 10.1016/j.bbrc.2019.05.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 05/09/2019] [Indexed: 01/03/2023]
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22
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Layton AT, Layton HE. A computational model of epithelial solute and water transport along a human nephron. PLoS Comput Biol 2019; 15:e1006108. [PMID: 30802242 PMCID: PMC6405173 DOI: 10.1371/journal.pcbi.1006108] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 03/07/2019] [Accepted: 03/26/2018] [Indexed: 01/08/2023] Open
Abstract
We have developed the first computational model of solute and water transport from Bowman space to the papillary tip of the nephron of a human kidney. The nephron is represented as a tubule lined by a layer of epithelial cells, with apical and basolateral transporters that vary according to cell type. The model is formulated for steady state, and consists of a large system of coupled ordinary differential equations and algebraic equations. Model solution describes luminal fluid flow, hydrostatic pressure, luminal fluid solute concentrations, cytosolic solute concentrations, epithelial membrane potential, and transcellular and paracellular fluxes. We found that if we assume that the transporter density and permeabilities are taken to be the same between the human and rat nephrons (with the exception of a glucose transporter along the proximal tubule and the H+-pump along the collecting duct), the model yields segmental deliveries and urinary excretion of volume and key solutes that are consistent with human data. The model predicted that the human nephron exhibits glomerulotubular balance, such that proximal tubular Na+ reabsorption varies proportionally to the single-nephron glomerular filtration rate. To simulate the action of a novel diabetic treatment, we inhibited the Na+-glucose cotransporter 2 (SGLT2) along the proximal convoluted tubule. Simulation results predicted that the segment’s Na+ reabsorption decreased significantly, resulting in natriuresis and osmotic diuresis. In addition to its well-known function of waste removal from the body, the kidney is also responsible for the critical regulation of the body’s salt, potassium, acid content, and blood pressure. The kidneys perform these life-sustaining task by filtering and returning to blood stream about 200 quarts of blood every 24 hours. What isn’t returned to blood stream is excreted as urine. The production of urine involves highly complex steps of secretion and reabsorption. To study these processes without employing invasive experimental procedures, we developed the first computational model of the human nephron (which is the functional unit of a kidney). The model contains detailed representation of the transport processes that take place in the epithelial cells that form the walls of the nephron. Using that model, we conducted simulations to predict how much filtered solutes and and water is transported along each individual and functionally distinct nephron segment. We conducted these simulations under normal physiological conditions, and under pharmacological conditions. The nephron model can be used as an essential component in an integrated model of kidney function in humans.
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Affiliation(s)
- Anita T. Layton
- Department of Mathematics, Duke University, Durham, North Carolina, United States of America
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
- Departments of Applied Mathematics and Biology, School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
- * E-mail:
| | - Harold E. Layton
- Department of Mathematics, Duke University, Durham, North Carolina, United States of America
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23
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Hepatocyte CYP2B6 Can Be Expressed in Cell Culture Systems by Exerting Physiological Levels of Shear: Implications for ADME Testing. J Toxicol 2017; 2017:1907952. [PMID: 29081796 PMCID: PMC5610861 DOI: 10.1155/2017/1907952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 07/27/2017] [Accepted: 08/07/2017] [Indexed: 11/18/2022] Open
Abstract
Cytochrome 2B6 (CYP2B6) has substantial clinical effects on morbidity and mortality and its effects on drug metabolism should be part of hepatotoxicity screening. Examples of CYP2B6's impacts include its linkage to mortality during cyclophosphamide therapy and its role in determining hepatotoxicity and CNS toxicity during efavirenz therapy for HIV infection. CYP2B6 is key to metabolism of many common drugs from opioids to antidepressants, anesthetics, and anticonvulsants. But CYP2B6 has been extremely difficult to express in cell culture, and as a result, it has been largely deemphasized in preclinical toxicity studies. It has now been shown that CYP2B6 expression can be supported for extended periods of time using suspension culture techniques that exert physiological levels of shear. New understanding of CYP2B6 has identified five clinically significant genetic polymorphisms that have a high incidence in many populations and that convey a substantial dynamic range of activity. We propose that, with the use of culture devices exerting physiological shear levels, CYP2B6 dependent drug testing, including definition of polymorphisms and application of specific inhibitors, should be a standard part of preclinical absorption, distribution, metabolism, and excretion (ADME) testing.
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24
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Bhattacharyya S, Jean-Alphonse FG, Raghavan V, McGarvey JC, Rbaibi Y, Vilardaga JP, Carattino MD, Weisz OA. Cdc42 activation couples fluid shear stress to apical endocytosis in proximal tubule cells. Physiol Rep 2017; 5:5/19/e13460. [PMID: 29038362 PMCID: PMC5641940 DOI: 10.14814/phy2.13460] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 08/30/2017] [Accepted: 09/04/2017] [Indexed: 11/24/2022] Open
Abstract
Cells lining the kidney proximal tubule (PT) respond to acute changes in glomerular filtration rate and the accompanying fluid shear stress (FSS) to regulate reabsorption of ions, glucose, and other filtered molecules and maintain glomerulotubular balance. Recently, we discovered that exposure of PT cells to FSS also stimulates an increase in apical endocytic capacity (Raghavan et al. PNAS, 111:8506–8511, 2014). We found that FSS triggered an increase in intracellular Ca2+ concentration ([Ca2+]i) that required release of extracellular ATP and the presence of primary cilia. In this study, we elucidate steps downstream of the increase in [Ca2+]i that link FSS‐induced calcium increase to increased apical endocytic capacity. Using an intramolecular FRET probe, we show that activation of Cdc42 is a necessary step in the FSS‐stimulated apical endocytosis cascade. Cdc42 activation requires the primary cilia and the FSS‐mediated increase in [Ca2+]i. Moreover, Cdc42 activity and FSS‐stimulated endocytosis are coordinately modulated by activators and inhibitors of calmodulin. Together, these data suggest a mechanism by which PT cell exposure to FSS is translated into enhanced endocytic uptake of filtered molecules.
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Affiliation(s)
- Sohinee Bhattacharyya
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Frédéric G Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Venkatesan Raghavan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jennifer C McGarvey
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Marcelo D Carattino
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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25
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Long KR, Shipman KE, Rbaibi Y, Menshikova EV, Ritov VB, Eshbach ML, Jiang Y, Jackson EK, Baty CJ, Weisz OA. Proximal tubule apical endocytosis is modulated by fluid shear stress via an mTOR-dependent pathway. Mol Biol Cell 2017; 28:2508-2517. [PMID: 28720662 PMCID: PMC5597323 DOI: 10.1091/mbc.e17-04-0211] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/07/2017] [Accepted: 07/13/2017] [Indexed: 12/02/2022] Open
Abstract
Kidney proximal tubule cells cultured under shear stress become remarkably well differentiated and endocytic capacity is rapidly tuned in response to acute changes in shear stress. The results have implications for understanding how proximal tubule function is regulated acutely by daily variations in glomerular filtration rate. Cells lining the proximal tubule (PT) have unique membrane specializations that are required to maintain the high-capacity ion transport and endocytic functions of this nephron segment. PT cells in vivo acutely regulate ion transport in response to changes in glomerular filtration rate (GFR) to maintain glomerulotubular balance. PT cells in culture up-regulate endocytic capacity in response to acute changes in fluid shear stress (FSS); however, it is not known whether GFR modulates PT endocytosis to enable maximally efficient uptake of filtered proteins in vivo. Here, we show that cells cultured under continuous FSS develop an expanded apical endocytic pathway and increased endocytic capacity and lysosomal biogenesis. Furthermore, endocytic capacity in fully differentiated cells is rapidly modulated by changes in FSS. PT cells exposed to continuous FSS also acquired an extensive brush border and basolateral membrane invaginations resembling those observed in vivo. Culture under suboptimal levels of FSS led to intermediate phenotypes, suggesting a threshold effect. Cells exposed to FSS expressed higher levels of key proteins necessary for PT function, including ion transporters, receptors, and membrane-trafficking machinery, and increased adenine nucleotide levels. Inhibition of the mechanistic target of rapamycin (mTOR) using rapamycin prevented the increase in cellular energy levels, lysosomal biogenesis, and endocytic uptake, suggesting that these represent a coordinated differentiation program. In contrast, rapamycin did not prevent the FSS-induced increase in Na+/K+-ATPase levels. Our data suggest that rapid tuning of the endocytic response by changes in FSS may contribute to glomerulotubular balance in vivo. Moreover, FSS provides an essential stimulus in the differentiation of PT cells via separate pathways that up-regulate endocytosis and ion transport capacity. Variations in FSS may also contribute to the maturation of PT cells during kidney development and during repair after kidney injury.
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Affiliation(s)
- Kimberly R Long
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Katherine E Shipman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Elizabeth V Menshikova
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Vladimir B Ritov
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Megan L Eshbach
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Catherine J Baty
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
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Christoffersson J, van Noort D, Mandenius CF. Developing organ-on-a-chip concepts using bio-mechatronic design methodology. Biofabrication 2017; 9:025023. [PMID: 28485301 DOI: 10.1088/1758-5090/aa71ca] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mechatronic design is an engineering methodology for conceiving, configuring and optimising the design of a technical device or product to the needs and requirements of the final user. In this article, we show how the basic principles of this methodology can be exploited for in vitro cell cultures-often referred to as organ-on-a-chip devices. Due to the key role of the biological cells, we have introduced the term bio-mechatronic design, to highlight the complexity of designing a system that should integrate biology, mechanics and electronics in the same device structure. The strength of the mechatronic design is to match the needs of the potential users to a systematic evaluation of overall functional design alternative. It may be especially attractive for organs-on-chips where biological constituents such as cells and tissues in 3D settings and in a fluidic environment should be compared, screened and selected. Through this approach, design solutions ranked to customer needs are generated according to specified criteria, thereby defining the key constraints of the fabrication. As an example, the bio-mechatronic methodology is applied to a liver-on-a-chip based on information extrapolated from previous theoretical and experimental knowledge. It is concluded that the methodology can generate new fabrication solutions for devices, as well as efficient guidelines for refining the design and fabrication of many of today's organ-on-a-chip devices.
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Layton AT, Edwards A, Vallon V. Adaptive changes in GFR, tubular morphology, and transport in subtotal nephrectomized kidneys: modeling and analysis. Am J Physiol Renal Physiol 2017; 313:F199-F209. [PMID: 28331059 DOI: 10.1152/ajprenal.00018.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/07/2017] [Accepted: 03/15/2017] [Indexed: 11/22/2022] Open
Abstract
Removal of renal mass stimulates anatomical and functional adaptations in the surviving nephrons, including elevations in single-nephron glomerular filtration rate (SNGFR) and tubular hypertrophy. A goal of this study is to assess the extent to which the concomitant increases in filtered load and tubular transport capacity preserve homeostasis of water and salt. To accomplish that goal, we developed computational models to simulate solute transport and metabolism along nephron populations in a uninephrectomized (UNX) rat and a 5/6-nephrectomized (5/6-NX) rat. Model simulations indicate that nephrectomy-induced SNGFR increase and tubular hypertrophy go a long way to normalize excretion, but alone are insufficient to fully maintain salt balance. We then identified increases in the protein density of Na+-K+-ATPase, Na+-K+-2Cl- cotransporter, Na+-Cl- cotransporter, and epithelial Na+ channel, such that the UNX and 5/6-NX models predict urine flow and urinary Na+ and K+ excretions that are similar to sham levels. The models predict that, in the UNX and 5/6-NX kidneys, fractional water and salt reabsorption is similar to sham along the initial nephron segments (i.e., from the proximal tubule to the distal convoluted tubule), with a need to further reduce Na+ reabsorption and increase K+ secretion primarily along the connecting tubules and collecting ducts to achieve balance. Additionally, the models predict that, given the substantially elevated filtered and thus transport load among each of the surviving nephrons, oxygen consumption per nephron segment in a UNX or 5/6-NX kidney increases substantially. But due to the reduced nephron population, whole animal renal oxygen consumption is lower. The efficiency of tubular Na+ transport in the UNX and 5/6-NX kidneys is predicted to be similar to sham.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina;
| | - Aurélie Edwards
- Centre National de la Recherche Scientifique, ERL 8228, Paris, France.,Department of Bioengineering, Boston University, Boston, Massachusetts
| | - Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego, La Jolla, California; and.,San Diego Veterans Affairs Healthcare System, San Diego, California
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Wang T, Weinbaum S, Weinstein AM. Regulation of glomerulotubular balance: flow-activated proximal tubule function. Pflugers Arch 2017; 469:643-654. [PMID: 28271233 DOI: 10.1007/s00424-017-1960-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 12/23/2022]
Abstract
The purpose of this review is to summarize our knowledge and understanding of the physiological importance and the mechanisms underlying flow-activated proximal tubule transport. Since the earliest micropuncture studies of mammalian proximal tubule, it has been recognized that tubular flow is an important regulator of sodium, potassium, and acid-base transport in the kidney. Increased fluid flow stimulates Na+ and HCO3- absorption in the proximal tubule via stimulation of Na/H-exchanger isoform 3 (NHE3) and H+-ATPase. In the proximal tubule, brush border microvilli are the major flow sensors, which experience changes in hydrodynamic drag and bending moment as luminal flow velocity changes and which transmit the force of altered flow to cytoskeletal structures within the cell. The signal to NHE3 depends upon the integrity of the actin cytoskeleton; the signal to the H+-ATPase depends upon microtubules. We have demonstrated that alterations in fluid drag impact tubule function by modulating ion transporter availability within the brush border membrane of the proximal tubule. Beyond that, there is evidence that transporter activity within the peritubular membrane is also modulated by luminal flow. Secondary messengers that regulate the flow-mediated tubule function have also been delineated. Dopamine blunts the responsiveness of proximal tubule transporters to changes in luminal flow velocity, while a DA1 antagonist increases flow sensitivity of solute reabsorption. IP3 receptor-mediated intracellular Ca2+ signaling is critical to transduction of microvillus drag. In this review, we summarize our findings of the regulatory mechanism of flow-mediated Na+ and HCO3- transport in the proximal tubule and review available information about flow sensing and regulatory mechanism of glomerulotubular balance.
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Affiliation(s)
- Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA.
| | - Sheldon Weinbaum
- Department of Biomedical Engineering, City College of New York, CUNY, New York, NY, USA
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY, USA
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Layton AT, Vallon V, Edwards A. A computational model for simulating solute transport and oxygen consumption along the nephrons. Am J Physiol Renal Physiol 2016; 311:F1378-F1390. [PMID: 27707705 DOI: 10.1152/ajprenal.00293.2016] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022] Open
Abstract
The goal of this study was to investigate water and solute transport, with a focus on sodium transport (TNa) and metabolism along individual nephron segments under differing physiological and pathophysiological conditions. To accomplish this goal, we developed a computational model of solute transport and oxygen consumption (QO2 ) along different nephron populations of a rat kidney. The model represents detailed epithelial and paracellular transport processes along both the superficial and juxtamedullary nephrons, with the loop of Henle of each model nephron extending to differing depths of the inner medulla. We used the model to assess how changes in TNa may alter QO2 in different nephron segments and how shifting the TNa sites alters overall kidney QO2 Under baseline conditions, the model predicted a whole kidney TNa/QO2 , which denotes the number of moles of Na+ reabsorbed per moles of O2 consumed, of ∼15, with TNa efficiency predicted to be significantly greater in cortical nephron segments than in medullary segments. The TNa/QO2 ratio was generally similar among the superficial and juxtamedullary nephron segments, except for the proximal tubule, where TNa/QO2 was ∼20% higher in superficial nephrons, due to the larger luminal flow along the juxtamedullary proximal tubules and the resulting higher, flow-induced transcellular transport. Moreover, the model predicted that an increase in single-nephron glomerular filtration rate does not significantly affect TNa/QO2 in the proximal tubules but generally increases TNa/QO2 along downstream segments. The latter result can be attributed to the generally higher luminal [Na+], which raises paracellular TNa Consequently, vulnerable medullary segments, such as the S3 segment and medullary thick ascending limb, may be relatively protected from flow-induced increases in QO2 under pathophysiological conditions.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina;
| | - Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego, La Jolla, California, and San Diego Veterans Affairs Healthcare System, San Diego, California
| | - Aurélie Edwards
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
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30
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Autophagy transduces physical constraints into biological responses. Int J Biochem Cell Biol 2016; 79:419-426. [PMID: 27566364 DOI: 10.1016/j.biocel.2016.08.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 12/15/2022]
Abstract
Autophagy is a fundamental cell biological process that controls the quality and quantity of the eukaryotic cytoplasm. Dysfunctional autophagy, when defective or excessive, has been linked to human pathologies ranging from neurodegenerative and infectious diseases to cancer and inflammatory diseases. Autophagy takes place at basal levels in all eukaryotic cells. The process is stimulated during metabolic, genotoxic, infectious, and hypoxic stress conditions and acts an adaptive mechanism essential for cell survival. Recent data demonstrate that changes in the mechanical cellular environment influence cell fate through the modulation of the autophagic pathway. Mechanical stimuli, such as applied forces, combine with biochemical signals to control development and physiological functions of different organs and can also contribute to the progression of various human diseases. Here we review recent findings regarding the regulation of autophagy upon three types of mechanical stress, compression, shear stress, and stretching, and discuss the potential implications of mechanical stress-induced autophagy in physiology and physiopathology.
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Abstract
PURPOSE OF REVIEW The proximal tubule plays a critical role in the reabsorption of ions, solutes and low molecular weight proteins from the glomerular filtrate. Although the proximal tubule has long been known to acutely modulate ion reabsorption in response to changes in flow rates of the glomerular filtrate, it has only recently been discovered that proximal tubule cells can similarly adjust endocytic capacity in response to flow. This review synthesizes our current understanding of mechanosensitive regulation of endocytic capacity in proximal tubule epithelia and highlights areas of opportunity for future investigations. RECENT FINDINGS Recent studies have reported that the endocytic capacity of proximal tubule cells is dramatically increased upon exposure to flow and the accompanying fluid shear stress. Modulation of this pathway is dependent on increases in intracellular calcium initiated by bending of the primary cilium, and also requires purinergic receptor activation that is mediated by release of extracellular ATP. This article summarizes what is currently known about the signaling cascade that transduces changes in flow into alterations in endocytosis. We discuss the implications of this newly described regulatory pathway with respect to our understanding of protein retrieval by the kidney under normal conditions, and in diseases that present with low molecular weight proteinuria. SUMMARY Primary cilia act as mechanotransducers that modulate apical endocytic capacity in proximal tubule cells in response to changes in fluid shear stress.
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Schillers H, Medalsy I, Hu S, Slade AL, Shaw JE. PeakForce Tapping resolves individual microvilli on living cells. J Mol Recognit 2016; 29:95-101. [PMID: 26414320 PMCID: PMC5054848 DOI: 10.1002/jmr.2510] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 12/18/2022]
Abstract
Microvilli are a common structure found on epithelial cells that increase the apical surface thus enhancing the transmembrane transport capacity and also serve as one of the cell's mechanosensors. These structures are composed of microfilaments and cytoplasm, covered by plasma membrane. Epithelial cell function is usually coupled to the density of microvilli and its individual size illustrated by diseases, in which microvilli degradation causes malabsorption and diarrhea. Atomic force microscopy (AFM) has been widely used to study the topography and morphology of living cells. Visualizing soft and flexible structures such as microvilli on the apical surface of a live cell has been very challenging because the native microvilli structures are displaced and deformed by the interaction with the probe. PeakForce Tapping® is an AFM imaging mode, which allows reducing tip-sample interactions in time (microseconds) and controlling force in the low pico-Newton range. Data acquisition of this mode was optimized by using a newly developed PeakForce QNM-Live Cell probe, having a short cantilever with a 17-µm-long tip that minimizes hydrodynamic effects between the cantilever and the sample surface. In this paper, we have demonstrated for the first time the visualization of the microvilli on living kidney cells with AFM using PeakForce Tapping. The structures observed display a force dependence representing either the whole microvilli or just the tips of the microvilli layer. Together, PeakForce Tapping allows force control in the low pico-Newton range and enables the visualization of very soft and flexible structures on living cells under physiological conditions.
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Affiliation(s)
- Hermann Schillers
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, Münster, 48149, Germany
| | - Izhar Medalsy
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - Shuiqing Hu
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - Andrea L Slade
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
| | - James E Shaw
- Bruker Nano Surfaces Division, 112 Robin Hill Rd, Santa Barbara, CA, 93117, USA
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Du Z, Duan Y, Yan Q, Weinbaum S, Weinstein AM, Wang T. Flow-activated proximal tubule function underlies glomerulotubular balance. THE KITASATO MEDICAL JOURNAL 2016; 46:105-117. [PMID: 31105444 PMCID: PMC6519745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Flow-modulated salt and water transport in proximal tubules has been recognized for more than four decades. Recent work has made major progress in defining the underlying cellular mechanisms. First, we demonstrated that perfusion-absorption balance is present in the isolated perfused proximal tubule of the mouse kidney, and thus is independent of neuronal control and systemic hormonal regulation. In proximal tubule, higher axial flow rates stimulate sodium and bicarbonate absorption by increased apical membrane Na+/H+-transporter and H-ATPase activity. It is also evident that fluid shear stress stimulates Na+/H+ exchanger isoform 3 (NHE3) exocytosis and trafficking to the apical membrane of the proximal tubule cells. Second, experimental data and modeling calculations provide strong evidence that brush border microvilli function as flow sensors in the proximal tubule. Flow-induced changes of proximal tubule absorption depend on the changes of torque (bending moment) on the microvilli, and that an intact actin cytoskeleton is required to transduce signals from the brush border to cell and alter transport activity, NHE3 expression and trafficking. Third, the increased NHE3 exocytosis by dopamine blockers enhanced tubule sensitivity to torque, and the IP3 receptor-mediated intracellular Ca2+ signaling is a critical step in transduction of fluid drag on microvillus drag tips in modulating Na+ and HCO3 - transport. Finally, in all of our experimental studies, flow-dependent transport in mouse tubules was achieved with virtually no change in tubule cell volume. Our model calculations suggest that this observation is strong evidence for proportional luminal and peritubular effects of flow on transporter density.
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Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT
| | - Yi Duan
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, NY
| | - QingShang Yan
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT
| | - Sheldon Weinbaum
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, NY
| | - Alan M. Weinstein
- Department of Biomedical Engineering, City College of New York, of the City University of New York, NY
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT
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34
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Fluid shear triggers microvilli formation via mechanosensitive activation of TRPV6. Nat Commun 2015; 6:8871. [PMID: 26563429 PMCID: PMC4660203 DOI: 10.1038/ncomms9871] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/12/2015] [Indexed: 12/15/2022] Open
Abstract
Microvilli are cellular membrane protrusions present on differentiated epithelial cells, which can sense and interact with the surrounding fluid environment. Biochemical and genetic approaches have identified a set of factors involved in microvilli formation; however, the underlying extrinsic regulatory mechanism of microvilli formation remains largely unknown. Here we demonstrate that fluid shear stress (FSS), an external mechanical cue, serves as a trigger for microvilli formation in human placental trophoblastic cells. We further reveal that the transient receptor potential, vanilloid family type-6 (TRPV6) calcium ion channel plays a critical role in flow-induced Ca2+ influx and microvilli formation. TRPV6 regulates phosphorylation of Ezrin via a Ca2+-dependent phosphorylation of Akt; this molecular event is necessary for microvillar localization of Ezrin in response to FSS. Our findings provide molecular insight into the microvilli-mediated mechanoresponsive cellular functions, such as epithelial absorption, signal perception and mechanotransduction. Microvilli on epithelial cells can sense the surrounding fluid environment, but the regulatory mechanism behind their formation is mostly unknown. Here Miura et al. show that fluid shear stress serves as a trigger for microvilli formation via activation of the calcium ion channel TRPV6.
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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36
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Abstract
The kidney filters vast quantities of Na at the glomerulus but excretes a very small fraction of this Na in the final urine. Although almost every nephron segment participates in the reabsorption of Na in the normal kidney, the proximal segments (from the glomerulus to the macula densa) and the distal segments (past the macula densa) play different roles. The proximal tubule and the thick ascending limb of the loop of Henle interact with the filtration apparatus to deliver Na to the distal nephron at a rather constant rate. This involves regulation of both filtration and reabsorption through the processes of glomerulotubular balance and tubuloglomerular feedback. The more distal segments, including the distal convoluted tubule (DCT), connecting tubule, and collecting duct, regulate Na reabsorption to match the excretion with dietary intake. The relative amounts of Na reabsorbed in the DCT, which mainly reabsorbs NaCl, and by more downstream segments that exchange Na for K are variable, allowing the simultaneous regulation of both Na and K excretion.
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Affiliation(s)
- Lawrence G Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York; and
| | - Jürgen Schnermann
- Kidney Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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37
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Weinstein AM. A mathematical model of rat proximal tubule and loop of Henle. Am J Physiol Renal Physiol 2015; 308:F1076-97. [PMID: 25694479 DOI: 10.1152/ajprenal.00504.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 02/10/2015] [Indexed: 01/11/2023] Open
Abstract
Proximal tubule and loop of Henle function are coupled, with proximal transport determining loop fluid composition, and loop transport modulating glomerular filtration via tubuloglomerular feedback (TGF). To examine this interaction, we begin with published models of the superficial rat proximal convoluted tubule (PCT; including flow-dependent transport in a compliant tubule), and the rat thick ascending Henle limb (AHL). Transport parameters for this PCT are scaled down to represent the proximal straight tubule (PST), which is connected to the thick AHL via a short descending limb. Transport parameters for superficial PCT and PST are scaled up for a juxtamedullary nephron, and connected to AHL via outer and inner medullary descending limbs, and inner medullary thin AHL. Medullary interstitial solute concentrations are specified. End-AHL hydrostatic pressure is determined by distal nephron flow resistance, and the TGF signal is represented as a linear function of end-AHL cytosolic Cl concentration. These two distal conditions required iterative solution of the model. Model calculations capture inner medullary countercurrent flux of urea, and also suggest the presence of an outer medullary countercurrent flux of ammonia, with reabsorption in AHL and secretion in PST. For a realistically strong TGF signal, there is the expected homeostatic impact on distal flows, and in addition, a homeostatic effect on proximal tubule pressure. The model glycosuria threshold is compatible with rat data, and predicted glucose excretion with selective 1Na(+):1glucose cotransporter (SGLT2) inhibition comports with observations in the mouse. Model calculations suggest that enhanced proximal tubule Na(+) reabsorption during hyperglycemia is sufficient to activate TGF and contribute to diabetic hyperfiltration.
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Affiliation(s)
- Alan M Weinstein
- Department of Physiology and Biophysics, Department of Medicine, Weill Medical College of Cornell University, New York, New York
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38
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Du Z, Weinbaum S, Weinstein AM, Wang T. Regulation of glomerulotubular balance. III. Implication of cytosolic calcium in flow-dependent proximal tubule transport. Am J Physiol Renal Physiol 2015; 308:F839-47. [PMID: 25651568 DOI: 10.1152/ajprenal.00601.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/25/2015] [Indexed: 11/22/2022] Open
Abstract
In the proximal tubule, axial flow (drag on brush-border microvilli) stimulates Na(+) and HCO3 (-) reabsorption by modulating both Na/H exchanger 3 (NHE3) and H-ATPase activity, a process critical to glomerulotubular balance. We have also demonstrated that blocking the angiotensin II receptor decreases baseline transport, but preserves the flow effect; dopamine leaves baseline fluxes intact, but abrogates the flow effect. In the current work, we provide evidence implicating cytosolic calcium in flow-dependent transport. Mouse proximal tubules were microperfused in vitro at perfusion rates of 5 and 20 nl/min, and reabsorption of fluid (Jv) and HCO3 (-) (JHCO3) were measured. We examined the effect of high luminal Ca(2+) (5 mM), 0 mM Ca(2+), the Ca(2+) chelator BAPTA-AM, the inositol 1,4,5-trisphosphate (IP3) receptor antagonist 2-aminoethoxydiphenyl borate (2-APB), and the Ca-ATPase inhibitor thapsigargin. In control tubules, increasing perfusion rate from 5 to 20 nl/min increased Jv by 62% and JHCO3 by 104%. With respect to Na(+) reabsorption, high luminal Ca(2+) decreased transport at low flow, but preserved the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect; thapsigargin decreased baseline flow, leaving the flow effect intact. With respect to HCO3 (-) reabsorption, high luminal Ca(2+) decreased transport at low flow and mildly diminished the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect. These data implicate IP3 receptor-mediated intracellular Ca(2+) signaling as a critical step in transduction of microvillous drag to modulate Na(+) and HCO3 (-) transport.
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Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Sheldon Weinbaum
- Department of Biomedical Engineering, City College of New York, CUNY, New York, New York; and
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut;
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Brasen JC, Burford JL, McDonough AA, Holstein-Rathlou NH, Peti-Peterdi J. Local pH domains regulate NHE3-mediated Na⁺ reabsorption in the renal proximal tubule. Am J Physiol Renal Physiol 2014; 307:F1249-62. [PMID: 25298526 DOI: 10.1152/ajprenal.00174.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The proximal tubule Na(+)/H(+) exchanger 3 (NHE3), located in the apical dense microvilli (brush border), plays a major role in the reabsorption of NaCl and water in the renal proximal tubule. In response to a rise in blood pressure NHE3 redistributes in the plane of the plasma membrane to the base of the brush border, where NHE3 activity is reduced. This NHE3 redistribution is assumed to provoke pressure natriuresis; however, it is unclear how NHE3 redistribution per se reduces NHE3 activity. To investigate if the distribution of NHE3 in the brush border can change the reabsorption rate, we constructed a spatiotemporal mathematical model of NHE3-mediated Na(+) reabsorption across a proximal tubule cell and compared the model results with in vivo experiments in rats. The model predicts that when NHE3 is localized exclusively at the base of the brush border, it creates local pH microdomains that reduce NHE3 activity by >30%. We tested the model's prediction experimentally: the rat kidney cortex was loaded with the pH-sensitive fluorescent dye BCECF, and cells of the proximal tubule were imaged in vivo using confocal fluorescence microscopy before and after an increase of blood pressure by ∼50 mmHg. The experimental results supported the model by demonstrating that a rise of blood pressure induces the development of pH microdomains near the bottom of the brush border. These local changes in pH reduce NHE3 activity, which may explain the pressure natriuresis response to NHE3 redistribution.
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Affiliation(s)
- Jens Christian Brasen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark; and
| | - James L Burford
- Departments of Physiology and Biophysics and Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California; and
| | - Alicia A McDonough
- Department of Cell and Neurobiology, University of Southern California, Los Angeles, California
| | | | - Janos Peti-Peterdi
- Departments of Physiology and Biophysics and Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California; and
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40
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Pohl M, Shan Q, Petsch T, Styp-Rekowska B, Matthey P, Bleich M, Bachmann S, Theilig F. Short-term functional adaptation of aquaporin-1 surface expression in the proximal tubule, a component of glomerulotubular balance. J Am Soc Nephrol 2014; 26:1269-78. [PMID: 25270072 DOI: 10.1681/asn.2014020148] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/22/2014] [Indexed: 11/03/2022] Open
Abstract
Transepithelial water flow across the renal proximal tubule is mediated predominantly by aquaporin-1 (AQP1). Along this nephron segment, luminal delivery and transepithelial reabsorption are directly coupled, a phenomenon called glomerulotubular balance. We hypothesized that the surface expression of AQP1 is regulated by fluid shear stress, contributing to this effect. Consistent with this finding, we found that the abundance of AQP1 in brush border apical and basolateral membranes was augmented >2-fold by increasing luminal perfusion rates in isolated, microperfused proximal tubules for 15 minutes. Mouse kidneys with diminished endocytosis caused by a conditional deletion of megalin or the chloride channel ClC-5 had constitutively enhanced AQP1 abundance in the proximal tubule brush border membrane. In AQP1-transfected, cultured proximal tubule cells, fluid shear stress or the addition of cyclic nucleotides enhanced AQP1 surface expression and concomitantly diminished its ubiquitination. These effects were also associated with an elevated osmotic water permeability. In sum, we have shown that luminal surface expression of AQP1 in the proximal tubule brush border membrane is regulated in response to flow. Cellular trafficking, endocytosis, an intact endosomal compartment, and controlled protein stability are the likely prerequisites for AQP1 activation by enhanced tubular fluid shear stress, serving to maintain glomerulotubular balance.
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Affiliation(s)
- Marcus Pohl
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany
| | - Qixian Shan
- Institute of Physiology, Kiel University, Kiel, Germany
| | - Thomas Petsch
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany
| | | | - Patricia Matthey
- Institute of Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Markus Bleich
- Institute of Physiology, Kiel University, Kiel, Germany
| | | | - Franziska Theilig
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany; Institute of Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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41
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Shear stress-dependent regulation of apical endocytosis in renal proximal tubule cells mediated by primary cilia. Proc Natl Acad Sci U S A 2014; 111:8506-11. [PMID: 24912170 DOI: 10.1073/pnas.1402195111] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The kidney has an extraordinary ability to maintain stable fractional solute and fluid reabsorption over a wide range of glomerular filtration rates (GFRs). Internalization of filtered low molecular weight proteins, vitamins, hormones, and other small molecules is mediated by the proximal tubule (PT) multiligand receptors megalin and cubilin. Changes in GFR and the accompanying fluid shear stress (FSS) modulate acute changes in PT ion transport thought to be mediated by microvillar bending. We found that FSS also affects apical endocytosis in PT cells. Exposure of immortalized PT cell lines to physiologically relevant levels of FSS led to dramatically increased internalization of the megalin-cubilin ligand albumin as well as the fluid phase marker dextran. FSS-stimulated apical endocytosis was initiated between 15 and 30 min postinduction of FSS, occurred via a clathrin- and dynamin-dependent pathway, and was rapidly reversed upon removing the FSS. Exposure to FSS also caused a rapid elevation in intracellular Ca(2+) [Ca(2+)]i, which was not observed in deciliated cells, upon treatment with BAPTA-AM, or upon inclusion of apyrase in the perfusion medium. Strikingly, deciliation, BAPTA-AM, and apyrase also blocked the flow-dependent increase in endocytosis. Moreover, addition of ATP bypassed the need for FSS in enhancing endocytic capacity. Our studies suggest that increased [Ca(2+)]i and purinergic signaling in response to FSS-dependent ciliary bending triggers a rapid and reversible increase in apical endocytosis that contributes to the efficient retrieval of filtered proteins in the PT.
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Jang KJ, Mehr AP, Hamilton GA, McPartlin LA, Chung S, Suh KY, Ingber DE. Human kidney proximal tubule-on-a-chip for drug transport and nephrotoxicity assessment. Integr Biol (Camb) 2014; 5:1119-29. [PMID: 23644926 DOI: 10.1039/c3ib40049b] [Citation(s) in RCA: 516] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Kidney toxicity is one of the most frequent adverse events reported during drug development. The lack of accurate predictive cell culture models and the unreliability of animal studies have created a need for better approaches to recapitulate kidney function in vitro. Here, we describe a microfluidic device lined by living human kidney epithelial cells exposed to fluidic flow that mimics key functions of the human kidney proximal tubule. Primary kidney epithelial cells isolated from human proximal tubule are cultured on the upper surface of an extracellular matrix-coated, porous, polyester membrane that splits the main channel of the device into two adjacent channels, thereby creating an apical 'luminal' channel and a basal 'interstitial' space. Exposure of the epithelial monolayer to an apical fluid shear stress (0.2 dyne cm(-2)) that mimics that found in living kidney tubules results in enhanced epithelial cell polarization and primary cilia formation compared to traditional Transwell culture systems. The cells also exhibited significantly greater albumin transport, glucose reabsorption, and brush border alkaline phosphatase activity. Importantly, cisplatin toxicity and Pgp efflux transporter activity measured on-chip more closely mimic the in vivo responses than results obtained with cells maintained under conventional culture conditions. While past studies have analyzed kidney tubular cells cultured under flow conditions in vitro, this is the first report of a toxicity study using primary human kidney proximal tubular epithelial cells in a microfluidic 'organ-on-a-chip' microdevice. The in vivo-like pathophysiology observed in this system suggests that it might serve as a useful tool for evaluating human-relevant renal toxicity in preclinical safety studies.
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Affiliation(s)
- Kyung-Jin Jang
- Wyss Institute for Biologically Inspired Engineering at Harvard University, CLSB Bldg. 5th floor, 3 Blackfan Circle, Boston, MA 02115, USA.
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Grabias BM, Konstantopoulos K. The physical basis of renal fibrosis: effects of altered hydrodynamic forces on kidney homeostasis. Am J Physiol Renal Physiol 2013; 306:F473-85. [PMID: 24352503 DOI: 10.1152/ajprenal.00503.2013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Healthy kidneys are continuously exposed to an array of physical forces as they filter the blood: shear stress along the inner lumen of the tubules, distension of the tubular walls in response to changing fluid pressures, and bending moments along both the cilia and microvilli of individual epithelial cells that comprise the tubules. Dysregulation of kidney homeostasis via underlying medical conditions such as hypertension, diabetes, or glomerulonephritis fundamentally elevates the magnitudes of each principle force in the kidney and leads to fibrotic scarring and eventual loss of organ function. The purpose of this review is to summarize the progress made characterizing the response of kidney cells to pathological levels of mechanical stimuli. In particular, we examine important, mechanically responsive signaling cascades and explore fundamental changes in renal cell homeostasis after cyclic strain or fluid shear stress exposure. Elucidating the effects of these disease-related mechanical imbalances on endogenous signaling events in kidney cells presents a unique opportunity to better understand the fibrotic process.
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Affiliation(s)
- Bryan M Grabias
- Dept. of Chemical and Biomolecular Engineering, The Johns Hopkins Univ., New Engineering Bldg. 114, 3400 N. Charles St., Baltimore, MD 21218.
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44
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Tobar A, Ori Y, Benchetrit S, Milo G, Herman-Edelstein M, Zingerman B, Lev N, Gafter U, Chagnac A. Proximal tubular hypertrophy and enlarged glomerular and proximal tubular urinary space in obese subjects with proteinuria. PLoS One 2013; 8:e75547. [PMID: 24086563 PMCID: PMC3783420 DOI: 10.1371/journal.pone.0075547] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/19/2013] [Indexed: 12/29/2022] Open
Abstract
Background Obesity is associated with glomerular hyperfiltration, increased proximal tubular sodium reabsorption, glomerular enlargement and renal hypertrophy. A single experimental study reported an increased glomerular urinary space in obese dogs. Whether proximal tubular volume is increased in obese subjects and whether their glomerular and tubular urinary spaces are enlarged is unknown. Objective To determine whether proximal tubules and glomerular and tubular urinary space are enlarged in obese subjects with proteinuria and glomerular hyperfiltration. Methods Kidney biopsies from 11 non-diabetic obese with proteinuria and 14 non-diabetic lean patients with a creatinine clearance above 50 ml/min and with mild or no interstitial fibrosis were retrospectively analyzed using morphometric methods. The cross-sectional area of the proximal tubular epithelium and lumen, the volume of the glomerular tuft and of Bowman’s space and the nuclei number per tubular profile were estimated. Results Creatinine clearance was higher in the obese than in the lean group (P=0.03). Proteinuria was similarly increased in both groups. Compared to the lean group, the obese group displayed a 104% higher glomerular tuft volume (P=0.001), a 94% higher Bowman’s space volume (P=0.003), a 33% higher cross-sectional area of the proximal tubular epithelium (P=0.02) and a 54% higher cross-sectional area of the proximal tubular lumen (P=0.01). The nuclei number per proximal tubular profile was similar in both groups, suggesting that the increase in tubular volume is due to hypertrophy and not to hyperplasia. Conclusions Obesity-related glomerular hyperfiltration is associated with proximal tubular epithelial hypertrophy and increased glomerular and tubular urinary space volume in subjects with proteinuria. The expanded glomerular and urinary space is probably a direct consequence of glomerular hyperfiltration. These effects may be involved in the pathogenesis of obesity-related renal disease.
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Affiliation(s)
- Ana Tobar
- Department of Pathology, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yaacov Ori
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sydney Benchetrit
- Department of Nephrology, Meir Medical Center, Kfar Saba, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Gai Milo
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Boris Zingerman
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Netta Lev
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Uzi Gafter
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Avry Chagnac
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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Gonzalez J, Essig M, Klein J, Caubet C, Dissard R, Bascands JL, Schanstra JP, Buffin-Meyer B. [Renal urinary shear stress: a novel actor in nephropathies]. Med Sci (Paris) 2013; 29:279-85. [PMID: 23544382 DOI: 10.1051/medsci/2013293014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The role of fluid shear stress is well established in vascular pathophysiology. However, urinary shear stress now also appears as a key mechanism in the regulation of renal function. In addition, there is a growing body of evidence showing that modified urinary shear stress is involved in the development of nephropathies. Therefore we review here the state-of-the-art on the pathophysiological roles of urinary shear stress.
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Du Z, Wan L, Yan Q, Weinbaum S, Weinstein AM, Wang T. Regulation of glomerulotubular balance: II: impact of angiotensin II on flow-dependent transport. Am J Physiol Renal Physiol 2012; 303:F1507-16. [PMID: 22952281 DOI: 10.1152/ajprenal.00277.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Underlying glomerulotubular balance (GTB) is the impact of axial flow to regulate Na(+) and HCO(3)(-) transport by modulating Na(+)-H(+) exchanger 3 (NHE3) and H-ATPase activity. It is not known whether the cascade of events following a change in flow relies on local angiotensin (ANG II) generation or receptor availability. Mouse tubules were microperfused in vitro at flows of 5 and 20 nl/min, and net fluid (J(v)) and HCO(3)(-) (J(HCO3)) absorption and cell height were measured. Na(+) (J(Na)) and Cl(-) (J(Cl)) absorption and changes in microvillous torque were estimated. Raising flow increased Na(+) and HCO(3)(-) reabsorption but did not change either Cl(-) transport or cell volume. Losartan reduced absolute Na(+) and HCO(3)(-) absorption at both low and high flows but did not affect fractional flow-stimulated transport. Compared with controls, in AT(1a) knockout (KO) mouse tubules, 53% of flow-stimulated Na(+) absorption was abolished, but flow-stimulated HCO(3)(-) absorption was retained at similar levels. The remaining flow-stimulated J(HCO3) was eliminated by the H-ATPase inhibitor bafilomycin. Inhibition of the AT(2) receptor by PD123319 increased both J(Na) and J(HCO3) but did not affect flow-mediated fractional changes. NHE3 expression at the protein level was reduced in AT(1a) KO mice kidneys. We conclude that 1) although the AT(1a) receptor is necessary for flow to impact NHE3, the effect on H(+)-ATPase is independent of AT(1a); 2) the small flow-mediated changes in cell volume suggest a coordinate flow effect on both luminal and basolateral transporters; and 3) there is no evidence of flow-dependent Cl(-) transport, and thus no evidence for convective paracellular Cl(-) transport in mouse tubules.
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Affiliation(s)
- Zhaopeng Du
- Dept. of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520-8026, USA
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47
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Du Z, Yan Q, Wan L, Weinbaum S, Weinstein AM, Wang T. Regulation of glomerulotubular balance. I. Impact of dopamine on flow-dependent transport. Am J Physiol Renal Physiol 2012; 303:F386-95. [PMID: 22552936 DOI: 10.1152/ajprenal.00531.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In response to volume expansion, locally generated dopamine decreases proximal tubule reabsorption by reducing both Na/H-exchanger 3 (NHE3) and Na-K-ATPase activity. We have previously demonstrated that mouse proximal tubules in vitro respond to changes in luminal flow with proportional changes in Na(+) and HCO(3)(-) reabsorption and have suggested that this observation underlies glomerulotubular balance. In the present work, we investigate the impact of dopamine on the sensitivity of reabsorptive fluxes to changes in luminal flow. Mouse proximal tubules were microperfused in vitro at low and high flow rates, and volume and HCO(3)(-) reabsorption (J(v) and J(HCO3)) were measured, while Na(+) and Cl(-) reabsorption (J(Na) and J(Cl)) were estimated. Raising luminal flow increased J(v), J(Na), and J(HCO3) but did not change J(Cl). Luminal dopamine did not change J(v), J(Na), and J(HCO3) at low flow rates but completely abolished the increments of Na(+) absorption by flow and partially inhibited the flow-stimulated HCO(3)(-) absorption. The remaining flow-stimulated HCO(3)(-) absorption was completely abolished by bafilomycin. The DA1 receptor blocker SCH23390 and the PKA inhibitor H89 blocked the effect of exogenous dopamine and produced a two to threefold increase in the sensitivity of proximal Na(+) reabsorption to luminal flow rate. Under the variety of perfusion conditions, changes in cell volume were small and did not always parallel changes in Na(+) transport. We conclude that 1) dopamine inhibits flow-stimulated NHE3 activity by activation of the DA1 receptor via a PKA-mediated mechanism; 2) dopamine has no effect on flow-stimulated H-ATPase activity; 3) there is no evidence of flow stimulation of Cl(-) reabsorption; and 4) the impact of dopamine is a coordinated modulation of both luminal and peritubular Na(+) transporters.
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Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520-8026, USA
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Gutiérrez-Praena D, Jos A, Pichardo S, Moyano R, Blanco A, Monterde JG, Cameán AM. Time-dependent histopathological changes induced in Tilapia (Oreochromis niloticus) after acute exposure to pure cylindrospermopsin by oral and intraperitoneal route. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2012; 76:102-13. [PMID: 22019311 DOI: 10.1016/j.ecoenv.2011.10.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 09/30/2011] [Accepted: 10/06/2011] [Indexed: 05/11/2023]
Abstract
Although fish and aquatic organisms can be in contact with the cyanotoxin cylindrospermopsin (CYN), toxicological studies are practically nonexistent. CYN has a late and progressive acute toxicity in rodents, but no data have been reported in fish. In this work, tilapia (Oreochromis niloticus) were exposed for the first time to an acute dose of CYN (200 μg/kg fish) by intraperitoneal (i.p.) injection, and the effects were compared with the oral route (gavage). In both cases, fish were sacrificed after 24 h or 5 days of the toxin administration. CYN induced multiorganic damage, being the liver and kidney the main targets of toxicity. The histological findings were more pronounced after i.p. administration (in the liver, kidney, heart, gills) with the exception of the gastrointestinal tract. The time of sacrifice influenced the degree of histological damage in all organs studied, and was more severe after 5 d in comparison to 24 h. Moreover, CYN induced an increase in the average nuclear diameter of hepatocytes in the liver, and decreased cross sections of proximal and distal convoluted tubules in the kidney. The changes in these parameters were also more severe by i.p. route, and with the time of sacrifice, supporting the histopathological results obtained in these organs. Thus, both parameters could be useful for quantifying the extent of the damage in fish after CYN exposure.
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Affiliation(s)
- Daniel Gutiérrez-Praena
- Area of Toxicology, Faculty of Pharmacy, University of Seville, Profesor García González 2, 41012 Seville, Spain
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Liu W, Pastor-Soler NM, Schreck C, Zavilowitz B, Kleyman TR, Satlin LM. Luminal flow modulates H+-ATPase activity in the cortical collecting duct (CCD). Am J Physiol Renal Physiol 2012; 302:F205-15. [PMID: 21957178 PMCID: PMC3251342 DOI: 10.1152/ajprenal.00179.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 09/20/2011] [Indexed: 11/22/2022] Open
Abstract
Epithelial Na(+) channel (ENaC)-mediated Na(+) absorption and BK channel-mediated K(+) secretion in the cortical collecting duct (CCD) are modulated by flow, the latter requiring an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)), microtubule integrity, and exocytic insertion of preformed channels into the apical membrane. As axial flow modulates HCO(3)(-) reabsorption in the proximal tubule due to changes in both luminal Na(+)/H(+) exchanger 3 and H(+)-ATPase activity (Du Z, Yan Q, Duan Y, Weinbaum S, Weinstein AM, Wang T. Am J Physiol Renal Physiol 290: F289-F296, 2006), we sought to test the hypothesis that flow also regulates H(+)-ATPase activity in the CCD. H(+)-ATPase activity was assayed in individually identified cells in microperfused CCDs isolated from New Zealand White rabbits, loaded with the pH-sensitive dye BCECF, and then subjected to an acute intracellular acid load (NH(4)Cl prepulse technique). H(+)-ATPase activity was defined as the initial rate of bafilomycin-inhibitable cell pH (pH(i)) recovery in the absence of luminal K(+), bilateral Na(+), and CO(2)/HCO(3)(-), from a nadir pH of ∼6.2. We found that 1) an increase in luminal flow rate from ∼1 to 5 nl·min(-1)·mm(-1) stimulated H(+)-ATPase activity, 2) flow-stimulated H(+) pumping was Ca(2+) dependent and required microtubule integrity, and 3) basal and flow-stimulated pH(i) recovery was detected in cells that labeled with the apical principal cell marker rhodamine Dolichos biflorus agglutinin as well as cells that did not. We conclude that luminal flow modulates H(+)-ATPase activity in the rabbit CCD and that H(+)-ATPases therein are present in both principal and intercalated cells.
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Affiliation(s)
- Wen Liu
- Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1198, New York, NY 10029, USA
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Weinbaum S, Duan Y, Thi MM, You L. An Integrative Review of Mechanotransduction in Endothelial, Epithelial (Renal) and Dendritic Cells (Osteocytes). Cell Mol Bioeng 2011; 4:510-537. [PMID: 23976901 DOI: 10.1007/s12195-011-0179-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In this review we will examine from a biomechanical and ultrastructural viewpoint how the cytoskeletal specialization of three basic cell types, endothelial cells (ECs), epithelial cells (renal tubule) and dendritic cells (osteocytes), enables the mechano-sensing of fluid flow in both their native in vivo environment and in culture, and the downstream signaling that is initiated at the molecular level in response to fluid flow. These cellular responses will be discussed in terms of basic mysteries and paradoxes encountered by each cell type. In ECs fluid shear stress (FSS) is nearly entirely attenuated by the endothelial glycocalyx that covers their apical membrane and yet FSS is communicated to both intracellular and junctional molecular components in activating a wide variety of signaling pathways. The same is true in proximal tubule (PT) cells where a dense brush border of microvilli covers the apical surface and the flow at the apical membrane is negligible. A four decade old unexplained mystery is the ability of PT epithelia to reliably reabsorb 60% of the flow entering the tubule regardless of the glomerular filtration rate. In the cortical collecting duct (CCD) the flow rates are so low that a special sensing apparatus, a primary cilia is needed to detect very small variations in tubular flow. In bone it has been a century old mystery as to how osteocytes embedded in a stiff mineralized tissue are able to sense miniscule whole tissue strains that are far smaller than the cellular level strains required to activate osteocytes in vitro.
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Affiliation(s)
- Sheldon Weinbaum
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY 10031, USA
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