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Walker C, Talawalla T, Toth R, Ambekar A, Rea K, Chamian O, Fan F, Berezowska S, Rottenberg S, Madabhushi A, Maillard M, Barisoni L, Horlings HM, Janowczyk A. PatchSorter: a high throughput deep learning digital pathology tool for object labeling. NPJ Digit Med 2024; 7:164. [PMID: 38902336 PMCID: PMC11190251 DOI: 10.1038/s41746-024-01150-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 05/31/2024] [Indexed: 06/22/2024] Open
Abstract
The discovery of patterns associated with diagnosis, prognosis, and therapy response in digital pathology images often requires intractable labeling of large quantities of histological objects. Here we release an open-source labeling tool, PatchSorter, which integrates deep learning with an intuitive web interface. Using >100,000 objects, we demonstrate a >7x improvement in labels per second over unaided labeling, with minimal impact on labeling accuracy, thus enabling high-throughput labeling of large datasets.
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Affiliation(s)
- Cédric Walker
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Tasneem Talawalla
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Robert Toth
- Toth Technology LLC, Toth Technology LLC, New Brunswick, NJ, USA
| | - Akhil Ambekar
- Department of Pathology, Division of AI & Computational Pathology, Duke University, Durham, NC, USA
- AI Health, Duke University, Durham, NC, USA
| | - Kien Rea
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Oswin Chamian
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Fan Fan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Sabina Berezowska
- Institute of Pathology, Lausanne University Hospital, Lausanne, Switzerland
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Bern Center for Precision Medicine, University of Bern, Bern, Switzerland
| | - Anant Madabhushi
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
- Atlanta Veterans Medical Center, Atlanta, GA, USA
| | - Marie Maillard
- Institute of Pathology, Lausanne University Hospital, Lausanne, Switzerland
| | - Laura Barisoni
- Department of Pathology, Division of AI & Computational Pathology, Duke University, Durham, NC, USA
- Department of Medicine, Division of Nephrology, Duke University, Durham, NC, USA
| | - Hugo Mark Horlings
- Department of Pathology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Andrew Janowczyk
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA.
- Department of Oncology, Division of Precision Oncology, Geneva University Hospitals, Geneva, Switzerland.
- Department of Diagnostics, Division of Clinical Pathology, Geneva University Hospitals, Geneva, Switzerland.
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2
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Rodrigues MC, Oliveira LBF, Vieira MAR, Caruso-Neves C, Peruchetti DB. Receptor-mediated endocytosis in kidney cells during physiological and pathological conditions. CURRENT TOPICS IN MEMBRANES 2024; 93:1-25. [PMID: 39181576 DOI: 10.1016/bs.ctm.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Mammalian cell membranes are very dynamic where they respond to several environmental stimuli by rearranging the membrane composition by basic biological processes, including endocytosis. In this context, receptor-mediated endocytosis, either clathrin-dependent or caveolae-dependent, is involved in different physiological and pathological conditions. In the last years, an important amount of evidence has been reported that kidney function involves the modulation of different types of endocytosis, including renal protein handling. In addition, the dysfunction of the endocytic machinery is involved with the development of proteinuria as well as glomerular and tubular injuries observed in kidney diseases associated with hypertension, diabetes, and others. In this present review, we will discuss the mechanisms underlying the receptor-mediated endocytosis in different glomerular cells and proximal tubule epithelial cells as well as their modulation by different factors during physiological and pathological conditions. These findings could help to expand the current understanding regarding renal protein handling as well as identify possible new therapeutic targets to halt the progression of kidney disease.
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Affiliation(s)
- Mariana C Rodrigues
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Laura B F Oliveira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Maria Aparecida R Vieira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Celso Caruso-Neves
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Rio de Janeiro Innovation Network in Nanosystems for Health-NanoSAUDE/FAPERJ, Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Medicina Regenerativa, INCT-Regenera, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCTI, Rio de Janeiro, RJ, Brazil
| | - Diogo B Peruchetti
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil; Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica, INCT-NANOBiofar, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCTI, Belo Horizonte, MG, Brazil.
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3
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Satarug S, Vesey DA, Gobe GC, Phelps KR. The pathogenesis of albuminuria in cadmium nephropathy. Curr Res Toxicol 2023; 6:100140. [PMID: 38116328 PMCID: PMC10726218 DOI: 10.1016/j.crtox.2023.100140] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/16/2023] [Accepted: 11/30/2023] [Indexed: 12/21/2023] Open
Abstract
Background Urinary cadmium excretion (ECd) rises with renal tissue content of the metal. Whereas glomerulopathies are sometimes associated with massive albuminuria, tubular accumulation of Cd typically causes modest albuminuria. Since β2-microglobulinuria (Eβ2M) is an established marker of proximal tubular dysfunction, we hypothesized that a comparison of albuminuria (Ealb) to Eβ2M in Cd-exposed subjects would provide evidence of similar mishandling of both proteins. Methods To depict excretion rates per functional nephron, ECd, Ealb, and Eβ2M were normalized to creatinine clearance (Ccr), a surrogate for the glomerular filtration rate (GFR). Estimation of GFR itself (eGFR) was accomplished with CKD-EPI formulas (2009). Linear and logistic regression analyses were performed to relate Ealb/Ccr, Eβ2M/Ccr, and eGFR to several independent variables. Simple linear regressions of eGFR, Ealb/Ccr, and Eβ2M/Ccr on ECd/Ccr were examined before and after adjustment of dependent variables for age. All regressions were performed after log-transformation of ratios and standardization of all variables. Increments in Ealb/Ccr and Eβ2M/Ccr and decrements in eGFR were quantified through four quartiles of ECd/Ccr. Results As age or ECd/Ccr rose, Ealb/Ccr and Eβ2M/Ccr also rose, and eGFR fell. In linear regressions, slopes relating Ealb/Ccr and Eβ2M/Ccr to ECd/Ccr were similar. After adjustment of dependent variables for age, coefficients of determination (R2) for all regressions rose by a multiple, and slopes approached unity. Ealb/Ccr and Eβ2M/Ccr were similarly associated with each other. Mean Ealb/Ccr and Eβ2M/Ccr rose and mean eGFR fell in stepwise fashion through quartiles of ECd/Ccr. Whereas Eβ2M/Ccr did not vary with blood pressure, Ealb/Ccr rose in association with hypertension in two of the four quartiles. Conclusions Our data indicate that Cd in renal tissue affected tubular reabsorption of albumin and β2M similarly in a large cohort of exposed subjects. The results suggest that Cd reduced receptor-mediated endocytosis and subsequent lysosomal degradation of each protein by a shared mechanism.
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Affiliation(s)
- Soisungwan Satarug
- Centre for Kidney Disease Research, Translational Research Institute, Brisbane, Australia
| | - David A. Vesey
- Centre for Kidney Disease Research, Translational Research Institute, Brisbane, Australia
- Department of Kidney and Transplant Services, Princess Alexandra Hospital, Brisbane, Australia
| | - Glenda C. Gobe
- Centre for Kidney Disease Research, Translational Research Institute, Brisbane, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia
- NHMRC Centre of Research Excellence for CKD QLD, UQ Health Sciences, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Kenneth R. Phelps
- Stratton Veterans Affairs Medical Center and Albany Medical College, Albany, NY, USA
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4
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Thévenod F, Herbrechter R, Schlabs C, Pethe A, Lee WK, Wolff NA, Roussa E. Role of the SLC22A17/lipocalin-2 receptor in renal endocytosis of proteins/metalloproteins: a focus on iron- and cadmium-binding proteins. Am J Physiol Renal Physiol 2023; 325:F564-F577. [PMID: 37589051 DOI: 10.1152/ajprenal.00020.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/15/2023] [Accepted: 08/15/2023] [Indexed: 08/18/2023] Open
Abstract
The transmembrane protein SLC22A17 [or the neutrophil gelatinase-associated lipocalin/lipocalin-2 (LCN2)/24p3 receptor] is an atypical member of the SLC22 family of organic anion and cation transporters: it does not carry typical substrates of SLC22 transporters but mediates receptor-mediated endocytosis (RME) of LCN2. One important task of the kidney is the prevention of urinary loss of proteins filtered by the glomerulus by bulk reabsorption of multiple ligands via megalin:cubilin:amnionless-mediated endocytosis in the proximal tubule (PT). Accordingly, overflow, glomerular, or PT damage, as in Fanconi syndrome, results in proteinuria. Strikingly, up to 20% of filtered proteins escape the PT under physiological conditions and are reabsorbed by the distal nephron. The renal distal tubule and collecting duct express SLC22A17, which mediates RME of filtered proteins that evade the PT but with limited capacity to prevent proteinuria under pathological conditions. The kidney also prevents excretion of filtered essential and nonessential transition metals, such as iron or cadmium, respectively, that are largely bound to proteins with high affinity, e.g., LCN2, transferrin, or metallothionein, or low affinity, e.g., microglobulins or albumin. Hence, increased uptake of transition metals may cause nephrotoxicity. Here, we assess the literature on SLC22A17 structure, topology, tissue distribution, regulation, and assumed functions, emphasizing renal SLC22A17, which has relevance for physiology, pathology, and nephrotoxicity due to the accumulation of proteins complexed with transition metals, e.g., cadmium or iron. Other putative renal functions of SLC22A17, such as its contribution to osmotic stress adaptation, protection against urinary tract infection, or renal carcinogenesis, are discussed.
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Affiliation(s)
- Frank Thévenod
- Institute for Physiology, Pathophysiology and Toxicology, Center for Biomedical Education and Research, Witten/Herdecke University, Witten, Germany
- Physiology and Pathophysiology of Cells and Membranes, Medical School OWL, Bielefeld University, Bielefeld, Germany
| | - Robin Herbrechter
- Institute for Physiology, Pathophysiology and Toxicology, Center for Biomedical Education and Research, Witten/Herdecke University, Witten, Germany
| | - Carolin Schlabs
- Institute for Physiology, Pathophysiology and Toxicology, Center for Biomedical Education and Research, Witten/Herdecke University, Witten, Germany
| | - Abhishek Pethe
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Wing-Kee Lee
- Physiology and Pathophysiology of Cells and Membranes, Medical School OWL, Bielefeld University, Bielefeld, Germany
| | - Natascha A Wolff
- Institute for Physiology, Pathophysiology and Toxicology, Center for Biomedical Education and Research, Witten/Herdecke University, Witten, Germany
| | - Eleni Roussa
- Department of Molecular Embryology, Faculty of Medicine, Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg im Breisgau, Germany
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5
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Chen M, Gu X. Emerging roles of proximal tubular endocytosis in renal fibrosis. Front Cell Dev Biol 2023; 11:1235716. [PMID: 37799275 PMCID: PMC10547866 DOI: 10.3389/fcell.2023.1235716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/11/2023] [Indexed: 10/07/2023] Open
Abstract
Endocytosis is a crucial component of many pathological conditions. The proximal tubules are responsible for reabsorbing the majority of filtered water and glucose, as well as all the proteins filtered through the glomerular barrier via endocytosis, indicating an essential role in kidney diseases. Genetic mutations or acquired insults could affect the proximal tubule endocytosis processes, by disturbing or overstressing the endolysosomal system and subsequently activating different pathways, orchestrating renal fibrosis. This paper will review recent studies on proximal tubular endocytosis affected by other diseases and factors. Endocytosis plays a vital role in the development of renal fibrosis, and renal fibrosis could also, in turn, affect tubular endocytosis.
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Affiliation(s)
- Min Chen
- Department of Nephrology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xiangchen Gu
- Department of Nephrology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Medicine, Shanghai Hospital of Civil Aviation Administration of China, Shanghai, China
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6
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Wagner MC, Sandoval RM, Yadav SPS, Campos SB, Rhodes GJ, Phillips CL, Molitoris BA. Lrpap1 (RAP) Inhibits Proximal Tubule Clathrin Mediated and Clathrin Independent Endocytosis, Ameliorating Renal Aminoglycoside Nephrotoxicity. KIDNEY360 2023; 4:591-605. [PMID: 36848531 PMCID: PMC10278819 DOI: 10.34067/kid.0000000000000094] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 01/31/2023] [Indexed: 03/01/2023]
Abstract
Key Points Proximal tubule endocytosis of toxins often leads to nephrotoxicity. Inhibition of endocytosis with receptor-associated protein may serve as a clinical approach to reduce or eliminate kidney damage from a potential nephrotoxin. Background Proximal tubules (PTs) are exposed to many exogenous and endogenous nephrotoxins that pass through the glomerular filter. This includes many small molecules, such as aminoglycoside and myeloma light chains. These filtered molecules are rapidly endocytosed by the PTs and lead to nephrotoxicity. Methods To investigate whether inhibition of PT uptake of filtered toxins can reduce toxicity, we evaluated the ability of Lrpap1 or receptor-associated protein (RAP) to prevent PT endocytosis. Munich Wistar Frömter rats were used since both glomerular filtration and PT uptake can be visualized and quantified. The injury model chosen was the well-established gentamicin-induced toxicity, which leads to significant reductions in GFR and serum creatinine increases. CKD was induced with a right uninephrectomy and left 40-minute pedicle clamp. Rats had 8 weeks to recover and to stabilize GFR and proteinuria. Multiphoton microscopy was used to evaluate endocytosis in vivo and serum creatinine, and 24-hour creatinine clearances were used to evaluate kidney functional changes. Results Studies showed that preadministration of RAP significantly inhibited both albumin and dextran endocytosis in outer cortical PTs. Importantly, this inhibition was found to be rapidly reversible with time. RAP was also found to be an excellent inhibitor of PT gentamicin endocytosis. Finally, gentamicin administration for 6 days resulted in significant elevation of serum creatinine in vehicle-treated rats, but not in those receiving daily infusion of RAP before gentamicin. Conclusions This study provides a model for the potential use of RAP to prevent, in a reversible manner, PT endocytosis of potential nephrotoxins, thus protecting the kidney from damage.
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Affiliation(s)
- Mark C Wagner
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
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Kozyraki R, Verroust P, Cases O. Cubilin, the intrinsic factor-vitamin B12 receptor. VITAMINS AND HORMONES 2022; 119:65-119. [PMID: 35337634 DOI: 10.1016/bs.vh.2022.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cubilin (CUBN), the intrinsic factor-vitamin B12 receptor is a large endocytic protein involved in various physiological functions: vitamin B12 uptake in the gut; reabsorption of albumin and maturation of vitamin D in the kidney; nutrient delivery during embryonic development. Cubilin is an atypical receptor, peripherally associated to the plasma membrane. The transmembrane proteins amnionless (AMN) and Lrp2/Megalin are the currently known molecular partners contributing to plasma membrane transport and internalization of Cubilin. The role of Cubilin/Amn complex in the handling of vitamin B12 in health and disease has extensively been studied and so is the role of the Cubilin-Lrp2 tandem in renal pathophysiology. Accumulating evidence strongly supports a role of Cubilin in some developmental defects including impaired closure of the neural tube. Are these defects primarily caused by the dysfunction of a specific Cubilin ligand or are they secondary to impaired vitamin B12 or protein uptake? We will present the established Cubilin functions, discuss the developmental data and provide an overview of the emerging implications of Cubilin in the field of cardiovascular disease and cancer pathogenesis.
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Affiliation(s)
- Renata Kozyraki
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France.
| | - Pierre Verroust
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
| | - Olivier Cases
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, Université de Paris, Paris, France
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8
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Weisz OA. Endocytic adaptation to functional demand by the kidney proximal tubule. J Physiol 2021; 599:3437-3446. [PMID: 34036593 DOI: 10.1113/jp281599] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/06/2021] [Indexed: 12/28/2022] Open
Abstract
The kidney proximal tubule (PT) efficiently recovers the low level of albumin and other proteins that normally escape the glomerular filtration barrier. Two large receptors, megalin and cubilin/amnionless (CUBAM), bind to and efficiently retrieve these predominantly low molecular-weight proteins via clathrin-mediated endocytosis. Studies in cell culture models suggest that PT cells may sense changes in shear stress to modulate recovery of filtered proteins in response to normal variations in filtration rate. Impairments in PT endocytic function lead to the excretion of filtered proteins into the urine (tubular proteinuria). Remarkably, when the glomerular filtration barrier is breached, the PT is able to recover excess albumin with a capacity that is orders of magnitude higher than normal. What mediates this excess capacity for albumin uptake under nephrotic conditions, and why doesn't it compensate to prevent tubular proteinuria? Here we propose an integrated new working model to describe the PT recovery of filtered proteins under normal and nephrotic states. We hypothesize that uptake via the fluid phase provides excess capacity to recover high concentrations of filtered proteins under nephrotic conditions. Further, concentration of tubular fluid along the tubule axis will enhance the efficiency of uptake in more distal regions of the PT. By contrast to cells where fluid phase and receptor-mediated uptake are independent pathways, expression of megalin is required to maintain apical endocytic pathway integrity and is essential for both uptake mechanisms. This model accounts for both the high-affinity and the high-capacity responses to filtration load in physiological and pathological states.
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Affiliation(s)
- Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
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9
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The proximal tubule, protein uptake, and the riddle of the segments. Kidney Int 2021; 99:803-805. [PMID: 33745544 DOI: 10.1016/j.kint.2020.12.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 01/14/2023]
Abstract
The proximal tubule is divided anatomically into 3 distinct segments-S1 to S3-on the basis of differences in cellular ultrastructure, but the functional processes that define and shape these remain elusive. In a new study, Christensen used 3-dimensional nephron reconstruction, electron microscopy, and antibody staining to precisely map protein uptake to the structure of the proximal tubule. They reported striking axial patterns in endocytosis along the segments, which showed substantial plasticity in disease states.
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10
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Zhang C, Chen Y, Sun S, Zhang Y, Wang L, Luo Z, Liu M, Dong L, Dong N, Wu Q. A conserved LDL-receptor motif regulates corin and CD320 membrane targeting in polarized renal epithelial cells. eLife 2020; 9:56059. [PMID: 33136001 PMCID: PMC7605860 DOI: 10.7554/elife.56059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 10/19/2020] [Indexed: 12/27/2022] Open
Abstract
Selective protein distribution on distinct plasma membranes is important for epithelial cell function. To date, how proteins are directed to specific epithelial cell surface is not fully understood. Here we report a conserved DSSDE motif in LDL-receptor (LDLR) modules of corin (a transmembrane serine protease) and CD320 (a receptor for vitamin B12 uptake), which regulates apical membrane targeting in renal epithelial cells. Altering this motif prevents specific apical corin and CD320 expression in polarized Madin-Darby canine kidney (MDCK) cells. Mechanistic studies indicate that this DSSDE motif participates in a Rab11a-dependent mechanism that specifies apical sorting. In MDCK cells, inhibition of Rab11a, but not Rab11b, expression leads to corin and CD320 expression on both apical and basolateral membranes. Together, our results reveal a novel molecular recognition mechanism that regulates LDLR module-containing proteins in their specific apical expression in polarized renal epithelial cells.
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Affiliation(s)
- Ce Zhang
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China
| | - Yue Chen
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China
| | - Shijin Sun
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China.,MOH Key Laboratory of Thrombosis and Hemostasis, Jiangsu Institute of Hematology, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Yikai Zhang
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China.,MOH Key Laboratory of Thrombosis and Hemostasis, Jiangsu Institute of Hematology, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Lina Wang
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China
| | - Zhipu Luo
- Institute of Molecular Enzymology, Soochow University, Suzhou, China
| | - Meng Liu
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China
| | - Liang Dong
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China
| | - Ningzheng Dong
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China.,MOH Key Laboratory of Thrombosis and Hemostasis, Jiangsu Institute of Hematology, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Qingyu Wu
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Prevention, Soochow University, Suzhou, China.,Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
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11
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Ranjit S, Lanzanò L, Libby AE, Gratton E, Levi M. Advances in fluorescence microscopy techniques to study kidney function. Nat Rev Nephrol 2020; 17:128-144. [PMID: 32948857 DOI: 10.1038/s41581-020-00337-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Fluorescence microscopy, in particular immunofluorescence microscopy, has been used extensively for the assessment of kidney function and pathology for both research and diagnostic purposes. The development of confocal microscopy in the 1950s enabled imaging of live cells and intravital imaging of the kidney; however, confocal microscopy is limited by its maximal spatial resolution and depth. More recent advances in fluorescence microscopy techniques have enabled increasingly detailed assessment of kidney structure and provided extraordinary insights into kidney function. For example, nanoscale precise imaging by rapid beam oscillation (nSPIRO) is a super-resolution microscopy technique that was originally developed for functional imaging of kidney microvilli and enables detection of dynamic physiological events in the kidney. A variety of techniques such as fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS) and Förster resonance energy transfer (FRET) enable assessment of interaction between proteins. The emergence of other super-resolution techniques, including super-resolution stimulated emission depletion (STED), photoactivated localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM) and structured illumination microscopy (SIM), has enabled functional imaging of cellular and subcellular organelles at ≤50 nm resolution. The deep imaging via emission recovery (DIVER) detector allows deep, label-free and high-sensitivity imaging of second harmonics, enabling assessment of processes such as fibrosis, whereas fluorescence lifetime imaging microscopy (FLIM) enables assessment of metabolic processes.
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Affiliation(s)
- Suman Ranjit
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA. .,Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Luca Lanzanò
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy.,Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy
| | - Andrew E Libby
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA.
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12
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Ren Q, Weyer K, Rbaibi Y, Long KR, Tan RJ, Nielsen R, Christensen EI, Baty CJ, Kashlan OB, Weisz OA. Distinct functions of megalin and cubilin receptors in recovery of normal and nephrotic levels of filtered albumin. Am J Physiol Renal Physiol 2020; 318:F1284-F1294. [PMID: 32200668 DOI: 10.1152/ajprenal.00030.2020] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Proximal tubule (PT) cells express a single saturable albumin-binding site whose affinity matches the estimated tubular concentration of albumin; however, albumin uptake capacity is greatly increased under nephrotic conditions. Deciphering the individual contributions of megalin and cubilin to the uptake of normal and nephrotic levels of albumin is impossible in vivo, as knockout of megalin in mice globally disrupts PT endocytic uptake. We quantified concentration-dependent albumin uptake in an optimized opossum kidney cell culture model and fit the kinetic profiles to identify albumin-binding affinities and uptake capacities. Mathematical deconvolution fit best to a three-component model that included saturable high- and low-affinity uptake sites for albumin and underlying nonsaturable uptake consistent with passive uptake of albumin in the fluid phase. Knockdown of cubilin or its chaperone amnionless selectively reduced the binding capacity of the high-affinity site, whereas knockdown of megalin impacted the low-affinity site. Knockdown of disabled-2 decreased the capacities of both binding sites. Additionally, knockdown of megalin or disabled-2 profoundly inhibited the uptake of a fluid phase marker, with cubilin knockdown having a more modest effect. We propose a novel model for albumin retrieval along the PT in which cubilin and megalin receptors have different functions in recovering filtered albumin in proximal tubule cells. Cubilin binding to albumin is tuned to capture normally filtered levels of the protein. In contrast, megalin binding to albumin is of lower affinity, and its expression is also essential for enabling the recovery of high concentrations of albumin in the fluid phase.
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Affiliation(s)
- Qidong Ren
- School of Medicine, Tsinghua University, Beijing, China.,Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Kathrin Weyer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Kimberly R Long
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Roderick J Tan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Catherine J Baty
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ossama B Kashlan
- 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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