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Knol MGE, Wulfmeyer VC, Müller RU, Rinschen MM. Amino acid metabolism in kidney health and disease. Nat Rev Nephrol 2024:10.1038/s41581-024-00872-8. [PMID: 39198707 DOI: 10.1038/s41581-024-00872-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2024] [Indexed: 09/01/2024]
Abstract
Amino acids form peptides and proteins and are therefore considered the main building blocks of life. The kidney has an important but under-appreciated role in the synthesis, degradation, filtration, reabsorption and excretion of amino acids, acting to retain useful metabolites while excreting potentially harmful and waste products from amino acid metabolism. A complex network of kidney transporters and enzymes guides these processes and moderates the competing concentrations of various metabolites and amino acid products. Kidney amino acid metabolism contributes to gluconeogenesis, nitrogen clearance, acid-base metabolism and provision of fuel for tricarboxylic acid cycle and urea cycle intermediates, and is thus a central hub for homeostasis. Conversely, kidney disease affects the levels and metabolism of a variety of amino acids. Here, we review the metabolic role of the kidney in amino acid metabolism and describe how different diseases of the kidney lead to aberrations in amino acid metabolism. Improved understanding of the metabolic and communication routes that are affected by disease could provide new mechanistic insights into the pathogenesis of kidney diseases and potentially enable targeted dietary or pharmacological interventions.
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Affiliation(s)
- Martine G E Knol
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Internal Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | | | - Roman-Ulrich Müller
- Department II of Internal Medicine and Center for Molecular Medicine, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Markus M Rinschen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
- III Department of Medicine, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark.
- Hamburg Center for Kidney Health, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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2
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Ding Y, Luan ZQ, Mao ZM, Qu Z, Yu F. Association between glomerular mTORC1 activation and crescents formation in lupus nephritis patients. Clin Immunol 2023; 249:109288. [PMID: 36907538 DOI: 10.1016/j.clim.2023.109288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/30/2022] [Accepted: 02/23/2023] [Indexed: 03/13/2023]
Abstract
OBJECTIVE This study aims to explore the association between glomerular mammalian target of rapamycin complex 1 (mTORC1) pathway activation and crescents' degree in lupus nephritis (LN) patients. METHODS A total of 159 biopsy-proven LN patients were enrolled in this retrospective study. The clinical and pathological data of them were collected at the time of renal biopsy. mTORC1 pathway activation was measured by immunohistochemistry, expressed by the mean optical density (MOD) of p-RPS6 (ser235/236), and multiplexed immunofluorescence. The association of mTORC1 pathway activation with clinico-pathological features especially renal crescentic lesions, and the composite outcomes in LN patients was further analyzed. RESULTS mTORC1 pathway activation could be detected in the crescentic lesions and was positively correlated with the percentage of crescents (r = 0.479, P < 0.001) in LN patients. Subgroup analysis showed mTORC1 pathway was more activated in patients with cellular or fibrocellular crescentic lesions (P < 0.001), but not fibrous crescentic lesions (P = 0.270). The optimal cutoff value of the MOD of p-RPS6 (ser235/236) was 0.0111299 for predicting the presence of cellular-fibrocellular crescents in >7.39% of the glomeruli by the receiver operating characteristic curve. Cox regression survival analysis showed that mTORC1 pathway activation was an independent risk factor for the worse outcome (defined by composite endpoints of death, end-stage renal disease and a decrease of >30% in eGFR from baseline). CONCLUSION Activation of mTORC1 pathway was closely associated with the cellular-fibrocellular crescentic lesions and could be a prognostic marker in LN patients.
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Affiliation(s)
- Ying Ding
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing 100034, PR China; Department of Nephrology, Peking University International Hospital, Beijing 102206, PR China; Institute of Nephrology, Peking University, Beijing 100034, PR China; Key laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, PR China; Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing 100034, PR China
| | - Zhong-Qiu Luan
- Department of Nephrology, First Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin 150040, PR China
| | - Zhao-Min Mao
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing 100034, PR China; Institute of Nephrology, Peking University, Beijing 100034, PR China; Key laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, PR China; Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing 100034, PR China
| | - Zhen Qu
- Department of Nephrology, Peking University International Hospital, Beijing 102206, PR China.
| | - Feng Yu
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing 100034, PR China; Department of Nephrology, Peking University International Hospital, Beijing 102206, PR China; Institute of Nephrology, Peking University, Beijing 100034, PR China; Key laboratory of Renal Disease, Ministry of Health of China, Beijing 100034, PR China; Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing 100034, PR China
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3
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Zha D, Wu X. Nutrient sensing, signaling transduction, and autophagy in podocyte injury: implications for kidney disease. J Nephrol 2023; 36:17-29. [PMID: 35704261 DOI: 10.1007/s40620-022-01365-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/05/2022] [Indexed: 02/07/2023]
Abstract
Podocytes are terminally differentiated epithelial cells of the renal glomerular tuft and these highly specialized cells are essential for the integrity of the slit diaphragm. The biological function of podocytes is primarily based on a complex ramified structure that requires sufficient nutrients and a large supply of energy in support of their unique structure and function in the glomeruli. Of note, the dysregulation of nutrient signaling and energy metabolic pathways in podocytes has been associated with a range of kidney diseases i.e., diabetic nephropathy. Therefore, nutrient-related and energy metabolic signaling pathways are critical to maintaining podocyte homeostasis and the pathogenesis of podocyte injury. Recently, a growing body of evidence has indicated that nutrient starvation induces autophagy, which suggests crosstalk between nutritional signaling with the modulation of autophagy for podocytes to adapt to nutrient deprivation. In this review, the current knowledge and advancement in the understanding of nutrient sensing, signaling, and autophagy in the podocyte biology, injury, and pathogenesis of kidney diseases is summarized. Based on the existing findings, the implications and perspective to target these signaling pathways and autophagy in podocytes during the development of novel preventive and therapeutic strategies in patients with podocyte injury-associated kidney diseases are discussed.
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Affiliation(s)
- Dongqing Zha
- Division of Nephrology, Zhongnan Hospital of Wuhan University, 169 Donghu Road, Wuhan, 430070, Hubei, China
| | - Xiaoyan Wu
- Division of Nephrology, Zhongnan Hospital of Wuhan University, 169 Donghu Road, Wuhan, 430070, Hubei, China.
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4
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Venugopalan V, Rehders M, Weber J, Rodermund L, Al-Hashimi A, Bargmann T, Golchert J, Reinecke V, Homuth G, Völker U, Verrey F, Kirstein J, Heuer H, Schweizer U, Braun D, Wirth EK, Brix K. Lack of L-type amino acid transporter 2 in murine thyroid tissue induces autophagy. J Mol Endocrinol 2023; 70:JME-22-0060. [PMID: 36129170 DOI: 10.1530/jme-22-0060] [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: 08/18/2022] [Accepted: 09/21/2022] [Indexed: 01/19/2023]
Abstract
Proteolytic cleavage of thyroglobulin (Tg) for thyroid hormone (TH) liberation is followed by TH release from thyroid follicles into the circulation, enabled by TH transporters. The existence of a functional link between Tg-processing cathepsin proteases and TH transporters has been shown to be independent of the hypothalamus-pituitary-thyroid axis. Thus, lack of cathepsin K, combined with genetic defects in the TH transporters Mct8 and Mct10, that is the Ctsk-/-/Mct8-/y/Mct10-/- genotype, results in persistent Tg proteolysis due to autophagy induction. Because amino acid transport by L-type amino acid transporter 2 (Lat2) has been described to regulate autophagy, we asked whether Lat2 availability is affected in Ctsk-/-/Mct8-/y/Mct10-/- thyroid glands. Our data revealed that while mRNA amounts and subcellular localization of Lat2 remained unaltered in thyroid tissue of Ctsk-/-/Mct8-/y/Mct10-/- mice in comparison to WT controls, the Lat2 protein amounts were significantly reduced. These data suggest a direct link between Lat2 function and autophagy induction in Ctsk-/-/Mct8-/y/Mct10-/- mice. Indeed, thyroid tissue of Lat2-/- mice showed enhanced endo-lysosomal cathepsin activities, increased autophagosome formation, and enhanced autophagic flux. Collectively, these results suggest a mechanistic link between insufficient Lat2 protein function and autophagy induction in the thyroid gland of male mice.
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Affiliation(s)
| | - Maren Rehders
- School of Science, Jacobs University Bremen, Bremen, Germany
| | - Jonas Weber
- School of Science, Jacobs University Bremen, Bremen, Germany
| | - Lisa Rodermund
- School of Science, Jacobs University Bremen, Bremen, Germany
| | - Alaa Al-Hashimi
- School of Science, Jacobs University Bremen, Bremen, Germany
| | - Tonia Bargmann
- School of Science, Jacobs University Bremen, Bremen, Germany
| | - Janine Golchert
- Department of Functional Genomics, University Medicine Greifswald, Interfaculty Institute for Genetics and Functional Genomics, Greifswald, Germany
| | - Vivien Reinecke
- Department of Functional Genomics, University Medicine Greifswald, Interfaculty Institute for Genetics and Functional Genomics, Greifswald, Germany
| | - Georg Homuth
- Department of Functional Genomics, University Medicine Greifswald, Interfaculty Institute for Genetics and Functional Genomics, Greifswald, Germany
| | - Uwe Völker
- Department of Functional Genomics, University Medicine Greifswald, Interfaculty Institute for Genetics and Functional Genomics, Greifswald, Germany
| | - Francois Verrey
- Physiologisches Institut, Universität Zürich, Zürich, Switzerland
| | - Janine Kirstein
- Fachbereich 2 Biologie/Chemie, Faculty of Cell Biology, Universität Bremen, Bremen, Germany
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, Universitätsklinikum Essen, Essen, Germany
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Doreen Braun
- Institut für Biochemie und Molekularbiologie, Medizinische Fakultät, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Eva K Wirth
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Endocrinology and Metabolism, Berlin Institute of Health, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Germany
| | - Klaudia Brix
- School of Science, Jacobs University Bremen, Bremen, Germany
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5
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Hurkmans EGE, Koenderink JB, van den Heuvel JJMW, Versleijen-Jonkers YMH, Hillebrandt-Roeffen MHS, Groothuismink JM, Vos HI, van der Graaf WTA, Flucke U, Muradjan G, Schreuder HWB, Hagleitner MM, Brunner HG, Gelderblom H, Cleton-Jansen AM, Guchelaar HJ, de Bont ESJM, Touw DJ, Nijhoff GJ, Kremer LCM, Caron H, Windsor R, Patiño-García A, González-Neira A, Saletta F, McCowage G, Nagabushan S, Catchpoole D, te Loo DMWM, Coenen MJH. SLC7A8 coding for LAT2 is associated with early disease progression in osteosarcoma and transports doxorubicin. Front Pharmacol 2022; 13:1042989. [PMID: 36438828 PMCID: PMC9681801 DOI: 10.3389/fphar.2022.1042989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Abstract
Background: Despite (neo) adjuvant chemotherapy with cisplatin, doxorubicin and methotrexate, some patients with primary osteosarcoma progress during first-line systemic treatment and have a poor prognosis. In this study, we investigated whether patients with early disease progression (EDP), are characterized by a distinctive pharmacogenetic profile. Methods and Findings: Germline DNA from 287 Dutch high-grade osteosarcoma patients was genotyped using the DMET Plus array (containing 1,936 genetic markers in 231 drug metabolism and transporter genes). Associations between genetic variants and EDP were assessed using logistic regression models and associated variants (p <0.05) were validated in independent cohorts of 146 (Spain and United Kingdom) and 28 patients (Australia). In the association analyses, EDP was significantly associated with an SLC7A8 locus and was independently validated (meta-analysis validation cohorts: OR 0.19 [0.06–0.55], p = 0.002). The functional relevance of the top hits was explored by immunohistochemistry staining and an in vitro transport models. SLC7A8 encodes for the L-type amino acid transporter 2 (LAT2). Transport assays in HEK293 cells overexpressing LAT2 showed that doxorubicin, but not cisplatin and methotrexate, is a substrate for LAT2 (p < 0.0001). Finally, SLC7A8 mRNA expression analysis and LAT2 immunohistochemistry of osteosarcoma tissue showed that the lack of LAT2 expression is a prognostic factor of poor prognosis and reduced overall survival in patients without metastases (p = 0.0099 and p = 0.14, resp.). Conclusion: This study identified a novel locus in SLC7A8 to be associated with EDP in osteosarcoma. Functional studies indicate LAT2-mediates uptake of doxorubicin, which could give new opportunities to personalize treatment of osteosarcoma patients.
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Affiliation(s)
| | - Jan B. Koenderink
- Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | | | | | | | - Hanneke I. Vos
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Winette T. A. van der Graaf
- Department of Medical Oncology, Radboud University Medical Center, Nijmegen, Netherlands
- Department of Medical Oncology, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Uta Flucke
- Department of Pathology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Grigor Muradjan
- Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | | | - Han G. Brunner
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
| | - Hans Gelderblom
- Department of Medical Oncology, Leiden University Medical Center, Leiden, Netherlands
| | | | - Henk-Jan Guchelaar
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, Netherlands
| | - Eveline S. J. M. de Bont
- Department of Pediatrics, Beatrix Children’s Hospital, University Medical Center Groningen, Groningen, Netherlands
| | - Daan J. Touw
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, Netherlands
| | - G. Jan Nijhoff
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, Netherlands
| | - Leontien C. M. Kremer
- Department of Pediatrics, Amsterdam University Medical Centers, Emma Children’s Hospital, Amsterdam, Netherlands
| | - Huib Caron
- Department of Pediatrics, Amsterdam University Medical Centers, Emma Children’s Hospital, Amsterdam, Netherlands
| | - Rachael Windsor
- Pediatric & Adolescent Division, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Ana Patiño-García
- Department of Pediatrics, Clínica Universidad de Navarra, Solid Tumor Program, CIMA, Pamplona, Spain
| | - Anna González-Neira
- Human Genotyping Unit-CeGen, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Federica Saletta
- Children’s Cancer Research Unit, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - Geoff McCowage
- Cancer Centre for Children, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - Sumanth Nagabushan
- Cancer Centre for Children, The Children’s Hospital at Westmead, Sydney, NSW, Australia
- Discipline of Child and Adolescent Health, University of Sydney, Sydney, NSW, Australia
| | - Daniel Catchpoole
- Children’s Cancer Research Unit, The Children’s Hospital at Westmead, Sydney, NSW, Australia
| | - D. Maroeska W. M. te Loo
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, Nijmegen, Netherlands
| | - Marieke J. H. Coenen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, Netherlands
- *Correspondence: Marieke J. H. Coenen,
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6
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Hada I, Shimizu A, Takematsu H, Nishibori Y, Kimura T, Fukutomi T, Kudo A, Ito-Nitta N, Kiuchi Z, Patrakka J, Mikami N, Leclerc S, Akimoto Y, Hirayama Y, Mori S, Takano T, Yan K. A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2. J Am Soc Nephrol 2022; 33:2008-2025. [PMID: 35985815 PMCID: PMC9678040 DOI: 10.1681/asn.2022010070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 07/25/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The cause of podocyte injury in idiopathic nephrotic syndrome (INS) remains unknown. Although recent evidence points to the role of B cells and autoimmunity, the lack of animal models mediated by autoimmunity limits further research. We aimed to establish a mouse model mimicking human INS by immunizing mice with Crb2, a transmembrane protein expressed at the podocyte foot process. METHODS C3H/HeN mice were immunized with the recombinant extracellular domain of mouse Crb2. Serum anti-Crb2 antibody, urine protein-to-creatinine ratio, and kidney histology were studied. For signaling studies, a Crb2-expressing mouse podocyte line was incubated with anti-Crb2 antibody. RESULTS Serum anti-Crb2 autoantibodies and significant proteinuria were detected 4 weeks after the first immunization. The proteinuria reached nephrotic range at 9-13 weeks and persisted up to 29 weeks. Initial kidney histology resembled minimal change disease in humans, and immunofluorescence staining showed delicate punctate IgG staining in the glomerulus, which colocalized with Crb2 at the podocyte foot process. A subset of mice developed features resembling FSGS after 18 weeks. In glomeruli of immunized mice and in Crb2-expressing podocytes incubated with anti-Crb2 antibody, phosphorylation of ezrin, which connects Crb2 to the cytoskeleton, increased, accompanied by altered Crb2 localization and actin distribution. CONCLUSION The results highlight the causative role of anti-Crb2 autoantibody in podocyte injury in mice. Crb2 immunization could be a useful model to study the immunologic pathogenesis of human INS, and may support the role of autoimmunity against podocyte proteins in INS.
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Affiliation(s)
- Ichiro Hada
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan
| | - Hiromu Takematsu
- Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Yukino Nishibori
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Akihiko Kudo
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Noriko Ito-Nitta
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Zentaro Kiuchi
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden
| | - Naoaki Mikami
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Simon Leclerc
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Yoshihiro Akimoto
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Yoshiaki Hirayama
- Vaccine & Reagent, R&D Department, Denka Co., Ltd, Gosen-City, Japan
| | - Satoka Mori
- Denka Innovation Center, Denka Co., Ltd, Machida, Japan
| | - Tomoko Takano
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
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7
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Dinarvand M, Koch FC, Al Mouiee D, Vuong K, Vijayan A, Tanzim AF, Azad AKM, Penesyan A, Castaño-Rodríguez N, Vafaee F. dRNASb: a systems biology approach to decipher dynamics of host-pathogen interactions using temporal dual RNA-seq data. Microb Genom 2022; 8. [PMID: 36136078 DOI: 10.1099/mgen.0.000862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infection triggers a dynamic cascade of reciprocal events between host and pathogen wherein the host activates complex mechanisms to recognise and kill pathogens while the pathogen often adjusts its virulence and fitness to avoid eradication by the host. The interaction between the pathogen and the host results in large-scale changes in gene expression in both organisms. Dual RNA-seq, the simultaneous detection of host and pathogen transcripts, has become a leading approach to unravelling complex molecular interactions between the host and the pathogen and is particularly informative for intracellular organisms. The amount of in vitro and in vivo dual RNA-seq data is rapidly growing, which demands computational pipelines to effectively analyse such data. In particular, holistic, systems-level, and temporal analyses of dual RNA-seq data are essential to enable further insights into the host-pathogen transcriptional dynamics and potential interactions. Here, we developed an integrative network-driven bioinformatics pipeline, dRNASb, a systems biology-based computational pipeline to analyse temporal transcriptional clusters, incorporate molecular interaction networks (e.g. protein-protein interactions), identify topologically and functionally key transcripts in host and pathogen, and associate host and pathogen temporal transcriptome to decipher potential between-species interactions. The pipeline is applicable to various dual RNA-seq data from different species and experimental conditions. As a case study, we applied dRNASb to analyse temporal dual RNA-seq data of Salmonella-infected human cells, which enabled us to uncover genes contributing to the infection process and their potential functions and to identify putative associations between host and pathogen genes during infection. Overall, dRNASb has the potential to identify key genes involved in bacterial growth or host defence mechanisms for future uses as therapeutic targets.
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Affiliation(s)
- Mojdeh Dinarvand
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Forrest C Koch
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Daniel Al Mouiee
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
- UNSW Data Science Hub, University of New South Wales, Sydney, NSW, Australia
| | - Kaylee Vuong
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Abhishek Vijayan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Afia Fariha Tanzim
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - A K M Azad
- ProCan®, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia
| | - Anahit Penesyan
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, Australia
| | - Natalia Castaño-Rodríguez
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Fatemeh Vafaee
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
- UNSW Data Science Hub, University of New South Wales, Sydney, NSW, Australia
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8
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van der Wolde J, Haruhara K, Puelles VG, Nikolic-Paterson D, Bertram JF, Cullen-McEwen LA. The ability of remaining glomerular podocytes to adapt to the loss of their neighbours decreases with age. Cell Tissue Res 2022; 388:439-451. [PMID: 35290515 PMCID: PMC9035415 DOI: 10.1007/s00441-022-03611-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 03/01/2022] [Indexed: 02/06/2023]
Abstract
Progressive podocyte loss is a feature of healthy ageing. While previous studies have reported age-related changes in podocyte number, density and size and associations with proteinuria and glomerulosclerosis, few studies have examined how the response of remaining podocytes to podocyte depletion changes with age. Mild podocyte depletion was induced in PodCreiDTR mice aged 1, 6, 12 and 18 months via intraperitoneal administration of diphtheria toxin. Control mice received intraperitoneal vehicle. Podometrics, proteinuria and glomerular pathology were assessed, together with podocyte expression of p-rp-S6, a phosphorylation target that represents activity of the mammalian target of rapamycin (mTOR). Podocyte number per glomerulus did not change in control mice in the 18-month time period examined. However, control mice at 18 months had the largest podocytes and the lowest podocyte density. Podocyte depletion at 1, 6 and 12 months resulted in mild albuminuria but no glomerulosclerosis, whereas similar levels of podocyte depletion at 18 months resulted in both albuminuria and glomerulosclerosis. Following podocyte depletion at 6 and 12 months, the number of p-rp-S6 positive podocytes increased significantly, and this was associated with an adaptive increase in podocyte volume. However, at 18 months of age, remaining podocytes were unable to further elevate mTOR expression or undergo hypertrophic adaptation in response to mild podocyte depletion, resulting in marked glomerular pathology. These findings demonstrate the importance of mTORC1-mediated podocyte hypertrophy in both physiological (ageing) and adaptive settings, highlighting a functional limit to podocyte hypertrophy reached under physiological conditions.
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Affiliation(s)
- James van der Wolde
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - Kotaro Haruhara
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
- Division of Nephrology and Hypertension, Jikei University School of Medicine, Tokyo, Japan
| | - Victor G Puelles
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia
- Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - David Nikolic-Paterson
- Departments of Nephrology and Medicine, Monash Health and Monash University, Clayton, Vic, Australia
| | - John F Bertram
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
| | - Luise A Cullen-McEwen
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
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9
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Hagen CM, Roth E, Graf TR, Verrey F, Graf R, Gupta A, Pellegrini G, Poncet N, Camargo SMR. Loss of LAT1 sex-dependently delays recovery after caerulein-induced acute pancreatitis. World J Gastroenterol 2022; 28:1024-1054. [PMID: 35431492 PMCID: PMC8968515 DOI: 10.3748/wjg.v28.i10.1024] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/08/2021] [Accepted: 01/26/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The expression of amino acid transporters is known to vary during acute pancreatitis (AP) except for LAT1 (slc7a5), the expression of which remains stable. LAT1 supports cell growth by importing leucine and thereby stimulates mammalian target of rapamycin (mTOR) activity, a phenomenon often observed in cancer cells. The mechanisms by which LAT1 influences physiological and pathophysiological processes and affects disease progression in the pancreas are not yet known.
AIM To evaluate the role of LAT1 in the development of and recovery from AP.
METHODS AP was induced with caerulein (cae) injections in female and male mice expressing LAT1 or after its knockout (LAT1 Cre/LoxP). The development of the initial AP injury and its recovery were followed for seven days after cae injections by daily measuring body weight, assessing microscopical tissue architecture, mRNA and protein expression, protein synthesis, and enzyme activity levels, as well as by testing the recruitment of immune cells by FACS and ELISA.
RESULTS The initial injury, evaluated by measurements of plasma amylase, lipase, and trypsin activity, as well as the gene expression of dedifferentiation markers, did not differ between the groups. However, early metabolic adaptations that support regeneration at later stages were blunted in LAT1 knockout mice. Especially in females, we observed less mTOR reactivation and dysfunctional autophagy. The later regeneration phase was clearly delayed in female LAT1 knockout mice, which did not regain normal expression of the pancreas-specific differentiation markers recombining binding protein suppressor of hairless-like protein (rbpjl) and basic helix-loop-helix family member A15 (mist1). Amylase mRNA and protein levels remained lower, and, strikingly, female LAT1 knockout mice presented signs of fibrosis lasting until day seven. In contrast, pancreas morphology had returned to normal in wild-type littermates.
CONCLUSION LAT1 supports the regeneration of acinar cells after AP. Female mice lacking LAT1 exhibited more pronounced alterations than male mice, indicating a sexual dimorphism of amino acid metabolism.
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Affiliation(s)
- Cristina M Hagen
- Institute of Physiology, University of Zurich, Zurich 8057, ZH, Switzerland
| | - Eva Roth
- Institute of Physiology, University of Zurich, Zurich 8057, ZH, Switzerland
| | - Theresia Reding Graf
- Swiss Hepato-Pancreato-Biliary Center, Department of Visceral and Transplantation Surgery, Zurich University Hospital, Zurich 8091, ZH, Switzerland
| | - François Verrey
- Institute of Physiology, University of Zurich, Zurich 8057, ZH, Switzerland
| | - Rolf Graf
- Swiss Hepato-Pancreato-Biliary Center, Department of Visceral and Transplantation Surgery, Zurich University Hospital, Zurich 8091, ZH, Switzerland
| | - Anurag Gupta
- Swiss Hepato-Pancreato-Biliary Center, Department of Visceral and Transplantation Surgery, Zurich University Hospital, Zurich 8091, ZH, Switzerland
| | - Giovanni Pellegrini
- Institute of Veterinary Pathology, University of Zurich, Zurich 8057, ZH, Switzerland
| | - Nadège Poncet
- Institute of Physiology, University of Zurich, Zurich 8057, ZH, Switzerland
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10
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Li ZH, Guo XY, Quan XY, Yang C, Liu ZJ, Su HY, An N, Liu HF. The Role of Parietal Epithelial Cells in the Pathogenesis of Podocytopathy. Front Physiol 2022; 13:832772. [PMID: 35360248 PMCID: PMC8963495 DOI: 10.3389/fphys.2022.832772] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/07/2022] [Indexed: 02/05/2023] Open
Abstract
Podocytopathy is the most common feature of glomerular disorder characterized by podocyte injury- or dysfunction-induced excessive proteinuria, which ultimately develops into glomerulosclerosis and results in persistent loss of renal function. Due to the lack of self-renewal ability of podocytes, mild podocyte depletion triggers replacement and repair processes mostly driven by stem cells or resident parietal epithelial cells (PECs). In contrast, when podocyte recovery fails, activated PECs contribute to the establishment of glomerular lesions. Increasing evidence suggests that PECs, more than just bystanders, have a crucial role in various podocytopathies, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, diabetic nephropathy, IgA nephropathy, and lupus podocytopathy. In this review, we attempt to dissect the diverse role of PECs in the pathogenesis of podocytopathy based on currently available information.
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11
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Ni L, Yuan C, Wu X. The recruitment mechanisms and potential therapeutic targets of podocytes from parietal epithelial cells. J Transl Med 2021; 19:441. [PMID: 34674704 PMCID: PMC8529729 DOI: 10.1186/s12967-021-03101-z] [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: 07/01/2021] [Accepted: 10/01/2021] [Indexed: 01/02/2023] Open
Abstract
Podocytes are differentiated postmitotic cells which cannot be replaced after podocyte injury. The mechanism of podocyte repopulation after injury has aroused wide concern. Parietal epithelial cells (PECs) are heterogeneous and only a specific subpopulation of PECs has the capacity to replace podocytes. Major progress has been achieved in recent years regarding the role and function of a subset of PECs which could transdifferentiate toward podocytes. Additionally, several factors, such as Notch, Wnt/ß-catenin, Wilms’ tumor-1, miR-193a and growth arrest-specific protein 1, have been shown to be involved in these processes. Finally, PECs serve as a potential therapeutic target in the conditions of podocyte loss. In this review, we discuss the latest observations and concepts about the recruitment of podocytes from PECs in glomerular diseases as well as newly identified mechanisms and the most recent treatments for this process.
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Affiliation(s)
- Lihua Ni
- Department of Nephrology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, People's Republic of China
| | - Cheng Yuan
- Department of Gynecological Oncology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, People's Republic of China.
| | - Xiaoyan Wu
- Department of Nephrology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, People's Republic of China.
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12
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Kantipudi S, Fotiadis D. Yeast Cell-Based Transport Assay for the Functional Characterization of Human 4F2hc-LAT1 and -LAT2, and LAT1 and LAT2 Substrates and Inhibitors. Front Mol Biosci 2021; 8:676854. [PMID: 34124158 PMCID: PMC8193492 DOI: 10.3389/fmolb.2021.676854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 05/06/2021] [Indexed: 01/04/2023] Open
Abstract
In mammalian cells, the L-type amino acid transporters (LATs) LAT1 (SLC7A5) and LAT2 (SLC7A8) form heterodimeric amino acid transporters (HATs) with the ancillary protein 4F2hc and are involved in the cellular uptake of specific amino acids. The HAT 4F2hc-LAT1 is found upregulated in various cancer cell types, while 4F2hc-LAT2 is a transporter for non-cancer cells. Preclinical studies have highlighted that 4F2hc-LAT1 plays an important role in tumor progression representing a valid anticancer target. Consequently, current research is focusing on the development of potent and specific human 4F2hc-LAT1 inhibitors. On the other hand, 4F2hc-LAT2 is emerging as target of other diseases, thus also gaining clinical interest. To determine affinity and specificity of substrates and inhibitors for 4F2hc-LAT1 or 4F2hc-LAT2, robust transport cell assays are indispensable. We have optimized and validated a transport assay using cells of the methylotrophic yeast Pichia pastoris stably overexpressing the human HATs 4F2hc-LAT1 or -LAT2, and the LATs LAT1 or LAT2 alone. The radioligand [3H]L-leucine was used as reporter and the substrates L-leucine, triiodothyronine (T3) and thyroxine (T4) as well as the inhibitors BCH and JPH203 (KYT-0353) for assay validation. Obtained half-maximal inhibitory concentrations also provided new insights, e.g., into the LAT specificity of the potent inhibitor JPH203 and on the potency of the thyroid hormones T3 and T4 to inhibit transport through human 4F2hc-LAT2. The LAT1 and LAT2 assays are of particular interest to determine possible implications and influences of 4F2hc in ligand binding and transport. In summary, the presented assays are valuable for characterization of ligands, e.g., towards 4F2hc-LAT1 specificity, and can also be applied for compound screening. Finally, our established approach and assay would also be applicable to other HATs and LATs of interest.
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Affiliation(s)
- Satish Kantipudi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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13
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Fairweather SJ, Shah N, Brӧer S. Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 21:13-127. [PMID: 33052588 DOI: 10.1007/5584_2020_584] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H+ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost β uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b0,+AT-rBAT and the SLC6 family heteromer B0AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.
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Affiliation(s)
- Stephen J Fairweather
- Research School of Biology, Australian National University, Canberra, ACT, Australia. .,Resarch School of Chemistry, Australian National University, Canberra, ACT, Australia.
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Stefan Brӧer
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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14
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Vadlakonda L, Indracanti M, Kalangi SK, Gayatri BM, Naidu NG, Reddy ABM. The Role of Pi, Glutamine and the Essential Amino Acids in Modulating the Metabolism in Diabetes and Cancer. J Diabetes Metab Disord 2020; 19:1731-1775. [PMID: 33520860 DOI: 10.1007/s40200-020-00566-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 06/04/2020] [Indexed: 02/07/2023]
Abstract
Purpose Re-examine the current metabolic models. Methods Review of literature and gene networks. Results Insulin activates Pi uptake, glutamine metabolism to stabilise lipid membranes. Tissue turnover maintains the metabolic health. Current model of intermediary metabolism (IM) suggests glucose is the source of energy, and anaplerotic entry of fatty acids and amino acids into mitochondria increases the oxidative capacity of the TCA cycle to produce the energy (ATP). The reduced cofactors, NADH and FADH2, have different roles in regulating the oxidation of nutrients, membrane potentials and biosynthesis. Trans-hydrogenation of NADH to NADPH activates the biosynthesis. FADH2 sustains the membrane potential during the cell transformations. Glycolytic enzymes assume the non-canonical moonlighting functions, enter the nucleus to remodel the genetic programmes to affect the tissue turnover for efficient use of nutrients. Glycosylation of the CD98 (4F2HC) stabilises the nutrient transporters and regulates the entry of cysteine, glutamine and BCAA into the cells. A reciprocal relationship between the leucine and glutamine entry into cells regulates the cholesterol and fatty acid synthesis and homeostasis in cells. Insulin promotes the Pi transport from the blood to tissues, activates the mitochondrial respiratory activity, and glutamine metabolism, which activates the synthesis of cholesterol and the de novo fatty acids for reorganising and stabilising the lipid membranes for nutrient transport and signal transduction in response to fluctuations in the microenvironmental cues. Fatty acids provide the lipid metabolites, activate the second messengers and protein kinases. Insulin resistance suppresses the lipid raft formation and the mitotic slippage activates the fibrosis and slow death pathways.
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Affiliation(s)
| | - Meera Indracanti
- Institute of Biotechnology, University of Gondar, Gondar, Ethiopia
| | - Suresh K Kalangi
- Amity Stem Cell Institute, Amity University Haryana, Amity Education Valley Pachgaon, Manesar, Gurugram, HR 122413 India
| | - B Meher Gayatri
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
| | - Navya G Naidu
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
| | - Aramati B M Reddy
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
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15
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Hamatani H, Eng DG, Hiromura K, Pippin JW, Shankland SJ. CD44 impacts glomerular parietal epithelial cell changes in the aged mouse kidney. Physiol Rep 2020; 8:e14487. [PMID: 32597007 PMCID: PMC7322268 DOI: 10.14814/phy2.14487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 05/17/2020] [Indexed: 02/06/2023] Open
Abstract
CD44 contributes to the activation of glomerular parietal epithelial cells (PECs). Although CD44 expression is higher in PECs of healthy aged mice, the biological role of CD44 in PECs in this context remains unclear. Accordingly, young (4 months) and aged (24 months) CD44-/- mice were compared to age-matched CD44+/+ mice, both aged in a nonstressed environment. Parietal epithelial cell densities were similar in both young and aged CD44+/+ and CD44-/- mice. Phosphorylated ERK 1/2 (pERK) was higher in aged CD44+/+ mice. Vimentin and α-SMA, markers of changes to the epithelial cell phenotype, were present in PECs in aged CD44+/+ mice, but absent in aged CD44-/- mice in both outer cortical (OC) and juxtamedullary (JM) glomeruli. Because age-related glomerular hypertrophy was lower in CD44-/- mice, mTOR activation was assessed by phospho-S6 ribosomal protein (pS6RP) staining. Parietal epithelial cells and glomerular tuft staining for pS6RP was lower in aged CD44-/- mice compared to aged CD44+/+ mice. Podocyte density was higher in aged CD44-/- mice in both OC and JM glomeruli. These changes were accompanied by segmental and global glomerulosclerosis in aged CD44+/+ mice, but absent in aged CD44-/- mice. These results show that the increase in CD44 in PECs in aged kidneys contributes to several changes to the glomerulus during healthy aging in mice, and may involve ERK and mTOR activation.
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Affiliation(s)
- Hiroko Hamatani
- Division of NephrologyUniversity of Washington School of MedicineSeattleWAUSA
- Department of Nephrology and RheumatologyGunma University Graduate School of MedicineMaebashiJapan
| | - Diana G. Eng
- Division of NephrologyUniversity of Washington School of MedicineSeattleWAUSA
| | - Keiju Hiromura
- Department of Nephrology and RheumatologyGunma University Graduate School of MedicineMaebashiJapan
| | - Jeffrey W. Pippin
- Division of NephrologyUniversity of Washington School of MedicineSeattleWAUSA
| | - Stuart J. Shankland
- Division of NephrologyUniversity of Washington School of MedicineSeattleWAUSA
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16
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Inhibition of mTOR delayed but could not prevent experimental collapsing focal segmental glomerulosclerosis. Sci Rep 2020; 10:8580. [PMID: 32444668 PMCID: PMC7244565 DOI: 10.1038/s41598-020-65352-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 04/30/2020] [Indexed: 02/06/2023] Open
Abstract
Anti-Thy1.1 transgenic mice develop glomerular lesions that mimic collapsing focal segmental glomerulosclerosis (FSGS) in humans with collapse of the glomerular tuft and marked hyperplasia of the parietal epithelial cells (PECs). Immunostaining of phosphor-S6 ribosomal protein (pS6RP) revealed high mTOR activity in PECs of the FSGS lesions of these mice. In this study we questioned whether the mTOR inhibitor rapamycin (sirolimus) could attenuate the development and progression of glomerulosclerotic lesions in the anti-Thy1.1 transgenic mice. We observed reduced mTOR signalling and proliferation in human parietal epithelial cells after rapamycin treatment. Experiments with anti-Thy1.1. mice showed that early treatment with sirolimus reduced the development of glomerular lesions and glomerular cell proliferation at day 4. Levels of albuminuria, podocyte injury and podocyte number were similar in the sirolimus and vehicle treated groups. The initial beneficial effects of sirolimus treatment were not observed at day 7. Late sirolimus treatment did not reduce albuminuria or the progression of glomerulosclerosis. Taken together, rapamycin attenuated PEC proliferation and the formation of early FSGS lesions in experimental FSGS and reduced human PEC proliferation in vitro. However, the initial inhibition of PEC proliferation did not translate into a decline of albuminuria nor in a sustained reduction in sclerotic lesions.
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17
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Amino acid transportation, sensing and signal transduction in the mammary gland: key molecular signalling pathways in the regulation of milk synthesis. Nutr Res Rev 2020; 33:287-297. [DOI: 10.1017/s0954422420000074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AbstractThe mammary gland, a unique exocrine organ, is responsible for milk synthesis in mammals. Neonatal growth and health are predominantly determined by quality and quantity of milk production. Amino acids are crucial maternal nutrients that are the building blocks for milk protein and are potential energy sources for neonates. Recent advances made regarding the mammary gland further demonstrate that some functional amino acids also regulate milk protein and fat synthesis through distinct intracellular and extracellular pathways. In the present study, we discuss recent advances in the role of amino acids (especially branched-chain amino acids, methionine, arginine and lysine) in the regulation of milk synthesis. The present review also addresses the crucial questions of how amino acids are transported, sensed and transduced in the mammary gland.
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18
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Scalise M, Pochini L, Galluccio M, Console L, Indiveri C. Glutamine transporters as pharmacological targets: From function to drug design. Asian J Pharm Sci 2020; 15:207-219. [PMID: 32373200 PMCID: PMC7193454 DOI: 10.1016/j.ajps.2020.02.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/18/2020] [Accepted: 02/29/2020] [Indexed: 12/17/2022] Open
Abstract
Among the different targets of administered drugs, there are membrane transporters that play also a role in drug delivery and disposition. Moreover, drug-transporter interactions are responsible for off-target effects of drugs underlying their toxicity. The improvement of the drug design process is subjected to the identification of those membrane transporters mostly relevant for drug absorption, delivery and side effect production. A peculiar group of proteins with great relevance to pharmacology is constituted by the membrane transporters responsible for managing glutamine traffic in different body districts. The interest around glutamine metabolism lies in its physio-pathological role; glutamine is considered a conditionally essential amino acid because highly proliferative cells have an increased request of glutamine that cannot be satisfied only by endogenous synthesis. Then, glutamine transporters provide cells with this special nutrient. Among the glutamine transporters, SLC1A5, SLC6A14, SLC6A19, SLC7A5, SLC7A8 and some members of SLC38 family are the best characterized, so far, in both physiological and pathological conditions. Few 3D structures have been solved by CryoEM; other structural data on these transporters have been obtained by computational analysis. Interactions with drugs have been described for several transporters of this group. For some of them, the studies are at an advanced stage, for others, the studies are still in nuce and novel biochemical findings open intriguing perspectives.
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Affiliation(s)
- Mariafrancesca Scalise
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende (CS) 87036, Italy
| | - Lorena Pochini
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende (CS) 87036, Italy
| | - Michele Galluccio
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende (CS) 87036, Italy
| | - Lara Console
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende (CS) 87036, Italy
| | - Cesare Indiveri
- Department of DiBEST (Biologia, Ecologia e Scienze della Terra), University of Calabria, Arcavacata di Rende (CS) 87036, Italy
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19
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Puelles VG, van der Wolde JW, Wanner N, Scheppach MW, Cullen-McEwen LA, Bork T, Lindenmeyer MT, Gernhold L, Wong MN, Braun F, Cohen CD, Kett MM, Kuppe C, Kramann R, Saritas T, van Roeyen CR, Moeller MJ, Tribolet L, Rebello R, Sun YB, Li J, Müller-Newen G, Hughson MD, Hoy WE, Person F, Wiech T, Ricardo SD, Kerr PG, Denton KM, Furic L, Huber TB, Nikolic-Paterson DJ, Bertram JF. mTOR-mediated podocyte hypertrophy regulates glomerular integrity in mice and humans. JCI Insight 2019; 4:99271. [PMID: 31534053 DOI: 10.1172/jci.insight.99271] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 08/08/2019] [Indexed: 02/06/2023] Open
Abstract
The cellular origins of glomerulosclerosis involve activation of parietal epithelial cells (PECs) and progressive podocyte depletion. While mammalian target of rapamycin-mediated (mTOR-mediated) podocyte hypertrophy is recognized as an important signaling pathway in the context of glomerular disease, the role of podocyte hypertrophy as a compensatory mechanism preventing PEC activation and glomerulosclerosis remains poorly understood. In this study, we show that glomerular mTOR and PEC activation-related genes were both upregulated and intercorrelated in biopsies from patients with focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, suggesting both compensatory and pathological roles. Advanced morphometric analyses in murine and human tissues identified podocyte hypertrophy as a compensatory mechanism aiming to regulate glomerular functional integrity in response to somatic growth, podocyte depletion, and even glomerulosclerosis - all of this in the absence of detectable podocyte regeneration. In mice, pharmacological inhibition of mTOR signaling during acute podocyte loss impaired hypertrophy of remaining podocytes, resulting in unexpected albuminuria, PEC activation, and glomerulosclerosis. Exacerbated and persistent podocyte hypertrophy enabled a vicious cycle of podocyte loss and PEC activation, suggesting a limit to its beneficial effects. In summary, our data highlight a critical protective role of mTOR-mediated podocyte hypertrophy following podocyte loss in order to preserve glomerular integrity, preventing PEC activation and glomerulosclerosis.
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Affiliation(s)
- Victor G Puelles
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia.,Department of Nephrology, Monash Health, Melbourne, Australia.,Center for Inflammatory Diseases, Monash University, Melbourne, Australia.,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - James W van der Wolde
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Nicola Wanner
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Luise A Cullen-McEwen
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Tillmann Bork
- Renal Division, University Medical Center Freiburg, Freiburg, Germany
| | - Maja T Lindenmeyer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lukas Gernhold
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Milagros N Wong
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabian Braun
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Clemens D Cohen
- Nephrological Center Medical Clinic and Polyclinic IV, University of Munich, Munich, Germany
| | - Michelle M Kett
- Cardiovascular Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | | | | | | | | | | | - Leon Tribolet
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Richard Rebello
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Yu By Sun
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Jinhua Li
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Gerhard Müller-Newen
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Aachen, Germany
| | - Michael D Hughson
- Department of Pathology, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Wendy E Hoy
- Centre for Chronic Disease, The University of Queensland, Brisbane, Queensland, Australia
| | - Fermin Person
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Wiech
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sharon D Ricardo
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Peter G Kerr
- Department of Nephrology, Monash Health, Melbourne, Australia.,Center for Inflammatory Diseases, Monash University, Melbourne, Australia
| | - Kate M Denton
- Cardiovascular Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Luc Furic
- Prostate Cancer Translational Research Laboratory, Peter MacCallum Cancer Centre.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Australia.,Cancer Program, Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - David J Nikolic-Paterson
- Department of Nephrology, Monash Health, Melbourne, Australia.,Center for Inflammatory Diseases, Monash University, Melbourne, Australia
| | - John F Bertram
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia
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20
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Yamada D, Kawabe K, Tosa I, Tsukamoto S, Nakazato R, Kou M, Fujikawa K, Nakamura S, Ono M, Oohashi T, Kaneko M, Go S, Hinoi E, Yoneda Y, Takarada T. Inhibition of the glutamine transporter SNAT1 confers neuroprotection in mice by modulating the mTOR-autophagy system. Commun Biol 2019; 2:346. [PMID: 31552299 PMCID: PMC6751179 DOI: 10.1038/s42003-019-0582-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 08/19/2019] [Indexed: 01/31/2023] Open
Abstract
The pathophysiological role of mammalian target of rapamycin complex 1 (mTORC1) in neurodegenerative diseases is established, but possible therapeutic targets responsible for its activation in neurons must be explored. Here we identified solute carrier family 38a member 1 (SNAT1, Slc38a1) as a positive regulator of mTORC1 in neurons. Slc38a1flox/flox and Synapsin I-Cre mice were crossed to generate mutant mice in which Slc38a1 was selectively deleted in neurons. Measurement of 2,3,5-triphenyltetrazolium chloride (TTC) or the MAP2-negative area in a mouse model of middle cerebral artery occlusion (MCAO) revealed that Slc38a1 deficiency decreased infarct size. We found a transient increase in the phosphorylation of p70S6k1 (pp70S6k1) and a suppressive effect of rapamycin on infarct size in MCAO mice. Autophagy inhibitors completely mitigated the suppressive effect of SNAT1 deficiency on neuronal cell death under in vitro stroke culture conditions. These results demonstrate that SNAT1 promoted ischemic brain damage via mTOR-autophagy system.
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Affiliation(s)
- Daisuke Yamada
- Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Kenji Kawabe
- Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Ikue Tosa
- Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Shunpei Tsukamoto
- Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Ryota Nakazato
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Miki Kou
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Koichi Fujikawa
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Saki Nakamura
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Mitsuaki Ono
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Toshitaka Oohashi
- Department of Molecular Biology and Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
| | - Mari Kaneko
- Laboratory for Animal Resource Development Unit and Genetic Engineering Team, RIKEN Center for Life Science Technologies, 2-2-3 Minatojima Minami, Chuou-ku, Kobe, Hyogo 650-0047 Japan
| | - Shioi Go
- Laboratory for Animal Resource Development Unit and Genetic Engineering Team, RIKEN Center for Life Science Technologies, 2-2-3 Minatojima Minami, Chuou-ku, Kobe, Hyogo 650-0047 Japan
| | - Eiichi Hinoi
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Yukio Yoneda
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192 Japan
| | - Takeshi Takarada
- Department of Regenerative Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558 Japan
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Association of crumbs homolog-2 with mTORC1 in developing podocyte. PLoS One 2018; 13:e0202400. [PMID: 30125302 PMCID: PMC6101391 DOI: 10.1371/journal.pone.0202400] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 08/02/2018] [Indexed: 02/06/2023] Open
Abstract
The evidence that gene mutations in the polarity determinant Crumbs homologs-2 (CRB2) cause congenital nephrotic syndrome suggests the functional importance of this gene product in podocyte development. Because another isoform, CRB3, was reported to repress the mechanistic/mammalian target of the rapamycin complex 1 (mTORC1) pathway, we examined the role of CRB2 function in developing podocytes in relation to mTORC1. In HEK-293 and MDCK cells constitutively expressing CRB2, we found that the protein localized to the apicolateral side of the cell plasma membrane and that this plasma membrane assembly required N-glycosylation. Confocal microscopy of the neonate mouse kidney revealed that both the tyrosine-phosphorylated form and non-phosphorylated form of CRB2 commence at the S-shaped body stage at the apicolateral side of podocyte precursor cells and move to foot processes in a capillary tuft pattern. The pattern of phosphorylated mTOR in developing podocytes was similar to that of CRB2 tyrosine phosphorylation. Additionally, the lack of a tyrosine phosphorylation site on CRB2 led to the reduced sensitivity of mTORC1 activation in response to energy starvation. CRB2 may play an important role in the mechanistic pathway of developing podocytes through tyrosine phosphorylation by associating with mTORC1 activation.
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Cellular and molecular mechanisms of kidney fibrosis. Mol Aspects Med 2018; 65:16-36. [PMID: 29909119 DOI: 10.1016/j.mam.2018.06.002] [Citation(s) in RCA: 280] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/12/2018] [Indexed: 12/14/2022]
Abstract
Renal fibrosis is the final pathological process common to any ongoing, chronic kidney injury or maladaptive repair. It is considered as the underlying pathological process of chronic kidney disease (CKD), which affects more than 10% of world population and for which treatment options are limited. Renal fibrosis is defined by excessive deposition of extracellular matrix, which disrupts and replaces the functional parenchyma that leads to organ failure. Kidney's histological structure can be divided into three main compartments, all of which can be affected by fibrosis, specifically termed glomerulosclerosis in glomeruli, interstitial fibrosis in tubulointerstitium and arteriosclerosis and perivascular fibrosis in vasculature. In this review, we summarized the different appearance, cellular origin and major emerging processes and mediators of fibrosis in each compartment. We also depicted and discussed the challenges in translation of anti-fibrotic treatment to clinical practice and discuss possible solutions and future directions.
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Takagi H, Nishibori Y, Katayama K, Katada T, Takahashi S, Kiuchi Z, Takahashi SI, Kamei H, Kawakami H, Akimoto Y, Kudo A, Asanuma K, Takematsu H, Yan K. USP40 gene knockdown disrupts glomerular permeability in zebrafish. Am J Physiol Renal Physiol 2017; 312:F702-F715. [DOI: 10.1152/ajprenal.00197.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 11/22/2022] Open
Abstract
Unbiased transcriptome profiling and functional genomics approaches have identified ubiquitin-specific protease 40 (USP40) as a highly specific glomerular transcript. This gene product remains uncharacterized, and its biological function is completely unknown. Here, we showed that mouse and rat glomeruli exhibit specific expression of the USP40 protein, which migrated at 150 kDa and was exclusively localized in the podocyte cytoplasm of the adult kidney. Double-labeling immunofluorescence staining and confocal microscopy analysis of fetal and neonate kidney samples revealed that USP40 was also expressed in the vasculature, including in glomerular endothelial cells at the premature stage. USP40 in cultured glomerular endothelial cells and podocytes was specifically localized to the intermediate filament protein nestin. In glomerular endothelial cells, immunoprecipitation confirmed actual protein-protein binding of USP40 with nestin, and USP40-small-interfering RNA transfection revealed significant reduction of nestin. In a rat model of minimal-change nephrotic syndrome, USP40 expression was apparently reduced, which was also associated with the reduction of nestin. Zebrafish morphants lacking Usp40 exhibited disorganized glomeruli with the reduction of the cell junction in the endothelium and foot process effacement in the podocytes. Permeability studies in these zebrafish morphants demonstrated a disruption of the selective glomerular permeability filter. These data indicate that USP40/Usp40 is a novel protein that might play a crucial role in glomerulogenesis and the glomerular integrity after birth through the modulation of intermediate filament protein homeostasis.
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Affiliation(s)
- Hisashi Takagi
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Yukino Nishibori
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Kan Katayama
- Division of Matrix Biology, Department of Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Tomohisa Katada
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Shohei Takahashi
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Zentaro Kiuchi
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Shin-Ichiro Takahashi
- Laboratory of Cell Regulation, Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hiroyasu Kamei
- Laboratory of Cell Regulation, Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Hayato Kawakami
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Yoshihiro Akimoto
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Akihiko Kudo
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Katsuhiko Asanuma
- Medical Innovation Center, TMK Project, Kyoto University Graduate School of Medicine, Kyoto, Japan; and
| | - Hiromu Takematsu
- Laboratory of Biochemistry, Human Health Science, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
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Abstract
In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman's capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and podocytes have a common mesenchymal origin and are the result of divergent differentiation during embryogenesis. Podocytes and PTECs are highly differentiated cells with well-established functions pertaining to the maintenance of the filtration barrier and transport, respectively. For PECs, no specific function other than a structural one has been known until recently. Possible important functions for PECs in the fate of the glomerulus in glomerular disease have now become apparent: (1) PECs may be involved in the replacement of lost podocytes; (2) PECs form the basis of extracapillary proliferative lesions and subsequent sclerosis in glomerular disease. In addition to the acknowledgement that PECs are crucial in glomerular disease, knowledge has been gained regarding the molecular processes driving the phenotypic changes and behavior of PECs. Understanding these molecular processes is important for the development of specific therapeutic approaches aimed at either stimulation of the regenerative function of PECs or inhibition of the pro-sclerotic action of PECs. In this review, we discuss recent advances pertaining to the role of PECs in glomerular regeneration and disease and address the major molecular processes involved.
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Roles of mTOR complexes in the kidney: implications for renal disease and transplantation. Nat Rev Nephrol 2016; 12:587-609. [PMID: 27477490 DOI: 10.1038/nrneph.2016.108] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses.
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McNicholas BA, Eng DG, Lichtnekert J, Rabinowitz PS, Pippin JW, Shankland SJ. Reducing mTOR augments parietal epithelial cell density in a model of acute podocyte depletion and in aged kidneys. Am J Physiol Renal Physiol 2016; 311:F626-39. [PMID: 27440779 PMCID: PMC5142165 DOI: 10.1152/ajprenal.00196.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 07/12/2016] [Indexed: 02/06/2023] Open
Abstract
Parietal epithelial cell (PEC) response to glomerular injury may underlie a common pathway driving fibrogenesis following podocyte loss that typifies several glomerular disorders. Although the mammalian target of rapamycin (mTOR) pathway is important in cell homeostasis, little is known of the biological role or impact of reducing mTOR activity on PEC response following podocyte depletion, nor in the aging kidney. The purpose of these studies was to determine the impact on PECs of reducing mTOR activity following abrupt experimental depletion in podocyte number, as well as in a model of chronic podocyte loss and sclerosis associated with aging. Podocyte depletion was induced by an anti-podocyte antibody and rapamycin started at day 5 until death at day 14 Reducing mTOR did not lead to a greater reduction in podocyte density, despite greater glomerulosclerosis. However, mTOR inhibition lead to an increase in PEC density and PEC-derived crescent formation. Additionally, markers of epithelial-to-mesenchymal transition (platelet-derived growth factor receptor-β, α-smooth muscle actin, Notch-3) and PEC activation (CD44, collagen IV) were further increased by mTOR reduction. Aged mice treated with rapamycin for 1, 2, and 10 wk before death at 26.5 mo (≈75-yr-old human age) had increased the number of glomeruli with a crescentic appearance. mTOR inhibition at either a high or low level lead to changes in PEC phenotype, indicating PEC morphology is sensitive to changes mediated by global mTOR inhibition.
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Affiliation(s)
| | - Diana G Eng
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | - Julia Lichtnekert
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | | | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | - Stuart J Shankland
- Division of Nephrology, University of Washington, Seattle, Washington; and
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Zhao Y, Wang L, Pan J. The role of L-type amino acid transporter 1 in human tumors. Intractable Rare Dis Res 2015; 4:165-9. [PMID: 26668776 PMCID: PMC4660857 DOI: 10.5582/irdr.2015.01024] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/14/2015] [Accepted: 08/18/2015] [Indexed: 12/17/2022] Open
Abstract
L-type amino acid transporter 1 (LAT1) is an L-type amino acid transporter and transports large neutral amino acids such as leucine, isoleucine, valine, phenylalanine, tyrosine, tryptophan, methionine, and histidine. LAT1 was found to be highly expressed especially in human cancer tissues, and up-regulated LAT1 can lead to dysfunction in human tumor cells. These findings suggest that LAT1 plays an important role in human tumors. This review provides an overview of the current understanding of LAT1 expression and its clinical significance and function in tumors.
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Affiliation(s)
- Yu Zhao
- University of Ji'nan Shandong Academy of Medical Science School of Medicine and Life Science, Ji'nan, China
- Shandong Medicinal Biotechnology Center, Ji'nan, China
| | - Lin Wang
- University of Ji'nan Shandong Academy of Medical Science School of Medicine and Life Science, Ji'nan, China
- Shandong Medicinal Biotechnology Center, Ji'nan, China
| | - Jihong Pan
- University of Ji'nan Shandong Academy of Medical Science School of Medicine and Life Science, Ji'nan, China
- Shandong Medicinal Biotechnology Center, Ji'nan, China
- Key Laboratory for Rare Diseases of Shandong Province, Ji'nan, China
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New insights into glomerular parietal epithelial cell activation and its signaling pathways in glomerular diseases. BIOMED RESEARCH INTERNATIONAL 2015; 2015:318935. [PMID: 25866774 PMCID: PMC4383425 DOI: 10.1155/2015/318935] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/28/2014] [Accepted: 09/01/2014] [Indexed: 12/26/2022]
Abstract
The glomerular parietal epithelial cells (PECs) have aroused an increasing attention recently. The proliferation of PECs is the main feature of crescentic glomerulonephritis; besides that, in the past decade, PEC activation has been identified in several types of noninflammatory glomerulonephropathies, such as focal segmental glomerulosclerosis, diabetic glomerulopathy, and membranous nephropathy. The pathogenesis of PEC activation is poorly understood; however, a few studies delicately elucidate the potential mechanisms and signaling pathways implicated in these processes. In this review we will focus on the latest observations and concepts about PEC activation in glomerular diseases and the newest identified signaling pathways in PEC activation.
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Grahammer F, Wanner N, Huber TB. mTOR controls kidney epithelia in health and disease. Nephrol Dial Transplant 2014; 29 Suppl 1:i9-i18. [PMID: 24493874 DOI: 10.1093/ndt/gft491] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Renal epithelial function is the cornerstone of key excretory processes performed by our kidneys. Most of these tasks need to be tightly controlled to keep our internal environment in balance. Recently, the mTOR signalling network emerged as a key pathway controlling renal epithelial cells from the glomerular tuft along the entire nephron. Both mTOR complexes, mTORC1 and mTORC2, regulate such diverse processes as glomerular filtration and the fine tuning of tubular electrolyte balance. Most importantly, dysregulation of mTOR signalling contributes to prevalent kidney diseases like diabetic nephropathy and cystic kidney disease. The following review shall summarize our current knowledge of the renal epithelial mTOR signalling system under physiological and pathophysiological conditions.
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Affiliation(s)
- Florian Grahammer
- Renal Division, Department of Medicine, University of Freiburg, Freiburg, Germany
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30
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Glomerular parietal epithelial cells in kidney physiology, pathology, and repair. Curr Opin Nephrol Hypertens 2014; 22:302-9. [PMID: 23518463 DOI: 10.1097/mnh.0b013e32835fefd4] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW We have summarized recently published glomerular parietal epithelial cell (PEC) research, focusing on their roles in glomerular development and physiology, and in certain glomerular diseases. The rationale is that PECs have been largely ignored until the recent availability of cell lineage tracing studies, human and murine PEC culture systems, and potential therapeutic interventions of PECs. RECENT FINDINGS Several new paradigms involving PECs have emerged demonstrating their significant contribution to glomerular physiology and numerous glomerular diseases. A subset of PECs serving as podocyte progenitors have been identified in normal human glomeruli. They provide a source for podocytes in adolescent mice, and their numbers increase in states of podocyte depletion. PEC progenitor number is increased by retinoids and angiotensin-converting enzyme inhibition. However, dysregulated growth of PEC progenitors leads to pseudo-crescent and crescent formation. In focal segmental glomerulosclerosis, considered a podocyte disease, activated PECs increase extracellular matrix production, which leads to synechial attachment and, when they move to the glomerular tuft, to segmental glomerulosclerosis. Finally, PECs might be adversely affected in proteinuric states by undergoing apoptosis. SUMMARY PECs play a critical role in glomerular repair through their progenitor function, but under certain circumstances paradoxically contribute to deterioration by augmenting scarring and crescent formation.
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Smeets B, Huber TB. Sestrin 2: a regulator of the glomerular parietal epithelial cell phenotype. Am J Physiol Renal Physiol 2014; 307:F798-9. [PMID: 25143460 DOI: 10.1152/ajprenal.00435.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Bart Smeets
- Department of Internal Medicine II, Nephrology and Clinical Immunology, RWTH Aachen University Hospital, Aachen, Germany;
| | - Tobias B Huber
- Renal Division, University Medical Center Freiburg, Freiburg, Germany; and BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University, Freiburg, Germany
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Pochini L, Scalise M, Galluccio M, Indiveri C. Membrane transporters for the special amino acid glutamine: structure/function relationships and relevance to human health. Front Chem 2014; 2:61. [PMID: 25157349 PMCID: PMC4127817 DOI: 10.3389/fchem.2014.00061] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/16/2014] [Indexed: 12/26/2022] Open
Abstract
Glutamine together with glucose is essential for body's homeostasis. It is the most abundant amino acid and is involved in many biosynthetic, regulatory and energy production processes. Several membrane transporters which differ in transport modes, ensure glutamine homeostasis by coordinating its absorption, reabsorption and delivery to tissues. These transporters belong to different protein families, are redundant and ubiquitous. Their classification, originally based on functional properties, has recently been associated with the SLC nomenclature. Function of glutamine transporters is studied in cells over-expressing the transporters or, more recently in proteoliposomes harboring the proteins extracted from animal tissues or over-expressed in microorganisms. The role of the glutamine transporters is linked to their transport modes and coupling with Na+ and H+. Most transporters share specificity for other neutral or cationic amino acids. Na+-dependent co-transporters efficiently accumulate glutamine while antiporters regulate the pools of glutamine and other amino acids. The most acknowledged glutamine transporters belong to the SLC1, 6, 7, and 38 families. The members involved in the homeostasis are the co-transporters B0AT1 and the SNAT members 1, 2, 3, 5, and 7; the antiporters ASCT2, LAT1 and 2. The last two are associated to the ancillary CD98 protein. Some information on regulation of the glutamine transporters exist, which, however, need to be deepened. No information at all is available on structures, besides some homology models obtained using similar bacterial transporters as templates. Some models of rat and human glutamine transporters highlight very similar structures between the orthologs. Moreover the presence of glycosylation and/or phosphorylation sites located at the extracellular or intracellular faces has been predicted. ASCT2 and LAT1 are over-expressed in several cancers, thus representing potential targets for pharmacological intervention.
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Affiliation(s)
- Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
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Succar L, Lai-Kwon J, Nikolic-Paterson DJ, Rangan GK. Induction monotherapy with sirolimus has selected beneficial effects on glomerular and tubulointersititial injury in nephrotoxic serum nephritis. Int J Nephrol Renovasc Dis 2014; 7:303-13. [PMID: 25071375 PMCID: PMC4111659 DOI: 10.2147/ijnrd.s64202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The study aimed to test the hypothesis that therapeutic treatment with a mammalian target of rapamycin complex 1 inhibitor reduces renal cell proliferation and attenuates glomerular and tubulointerstitial injury in the early phase of nephrotoxic serum nephritis (NSN) in rats. Methods Male Wistar-Kyoto rats received a single tail-vein injection of sheep anti-rat glomerular basement membrane serum (day 0) and were treated with vehicle or sirolimus (0.25 mg/kg/day by subcutaneous injection) from day 1 until day 14. Results Treatment with sirolimus attenuated kidney enlargement by 41% (P<0.05), improved endogenous creatinine clearance by 50% (P<0.05), and reduced glomerular and tubulointerstitial cell proliferation by 53% and 70%, respectively, (P<0.05 compared to vehicle) in rats with NSN. In glomeruli, sirolimus reduced segmental fibrinoid necrosis by 69%, autologous rat immunoglobulin G deposition, glomerular capillary tuft enlargement, and periglomerular myofibroblast (α-smooth muscle actin-positive cells) accumulation (all P<0.05) but did not significantly affect glomerular crescent formation (P=0.15), macrophage accumulation (P=0.25), or the progression of proteinuria. In contrast, sirolimus preserved tubulointerstitial structure and attenuated all markers of injury (interstitial ED-1- and α-smooth muscle actin-positive cells and tubular vimentin expression; all P<0.05). By immunohistochemistry and Western blot analysis, sirolimus reduced the glomerular and tubulointerstitial expression of phosphorylated (Ser 235/236) S6-ribosomal protein (P<0.05). Conclusion Induction monotherapy with sirolimus suppressed target of rapamycin complex 1 activation, renal cell proliferation, and injury during the early stages of rodent NSN, but the degree of histological protection was more consistent in the tubulointerstitium than the glomerular compartment.
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Affiliation(s)
- Lena Succar
- Centre for Transplant and Renal Research, Westmead Millennium Institute, University of Sydney, Westmead Hospital, Sydney, NSW, Australia
| | - Julia Lai-Kwon
- Centre for Transplant and Renal Research, Westmead Millennium Institute, University of Sydney, Westmead Hospital, Sydney, NSW, Australia
| | - David J Nikolic-Paterson
- Department of Nephrology and Monash University Department of Medicine, Monash Medical Centre, Clayton, VIC, Australia
| | - Gopala K Rangan
- Centre for Transplant and Renal Research, Westmead Millennium Institute, University of Sydney, Westmead Hospital, Sydney, NSW, Australia
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Hamatani H, Hiromura K, Sakairi T, Takahashi S, Watanabe M, Maeshima A, Ohse T, Pippin JW, Shankland SJ, Nojima Y. Expression of a novel stress-inducible protein, sestrin 2, in rat glomerular parietal epithelial cells. Am J Physiol Renal Physiol 2014; 307:F708-17. [PMID: 25056347 DOI: 10.1152/ajprenal.00625.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sestrin 2, initially identified as a p53 target protein, accumulates in cells exposed to stress and inhibits mammalian target of rapamycin (mTOR) signaling. In normal rat kidneys, sestrin 2 was selectively expressed in parietal epithelial cells (PECs), identified by the marker protein gene product 9.5. In adriamycin nephropathy, sestrin 2 expression decreased in PECs on day 14, together with increased expression of phosphorylated S6 ribosomal protein (P-S6RP), a downstream target of mTOR. Sestrin 2 expression was markedly decreased on day 42, coinciding with glomerulosclerosis and severe periglomerular fibrosis. In puromycin aminonucleoside nephropathy, decreased sestrin 2 expression, increased P-S6RP expression, and periglomerular fibrosis were observed on day 9, when massive proteinuria developed. These changes were transient and nearly normalized by day 28. In crescentic glomerulonephritis, sestrin 2 expression was not detected in cellular crescents, whereas P-S6RP increased. In conditionally immortalized cultured PECs, the forced downregulation of sestrin 2 by short hairpin RNA resulted in increased expression of P-S6RP and increased apoptosis. These data suggest that sestrin 2 is involved in PEC homeostasis by regulating the activity of mTOR. In addition, sestrin 2 could be a novel marker of PECs, and decreased expression of sestrin 2 might be a marker of PEC injury.
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Affiliation(s)
- Hiroko Hamatani
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Keiju Hiromura
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan;
| | - Toru Sakairi
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Satoshi Takahashi
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Mitsuharu Watanabe
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akito Maeshima
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takamoto Ohse
- Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Tokyo, Japan; and
| | - Jeffery W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington
| | | | - Yoshihisa Nojima
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Mao J, Zeng Z, Xu Z, Li J, Jiang L, Fang Y, Xu X, Hu Z, He W, Yang J, Dai C. Mammalian target of rapamycin complex 1 activation in podocytes promotes cellular crescent formation. Am J Physiol Renal Physiol 2014; 307:F1023-32. [PMID: 24990893 DOI: 10.1152/ajprenal.00018.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Podocytes play a key role in the formation of cellular crescents in experimental and human diseases. However, the underlying mechanisms for podocytes in promoting crescent formation need further investigation. Here, we demonstrated that mammalian target of rapamycin complex 1 (mTORC1) signaling was remarkably activated and hypoxia-inducible factor (HIF) 1α expression was largely induced in cellular crescents from patients with crescentic glomerular diseases. Specific deletion of Tsc1 in podocytes led to mTORC1 activation in podocytes and kidney dysfunction in mice. Interestingly, 33 of 36 knockouts developed cellular or mixed cellular and fibrous crescents at 7 wk of age (14.19±3.86% of total glomeruli in knockouts vs. 0% in control littermates, n=12-36, P=0.04). All of the seven knockouts developed crescents at 12 wk of age (30.92±11.961% of total glomeruli in knockouts vs. 0% in control littermates, n=4-7, P=0.002). Most notably, bridging cells between the glomerular tuft and the parietal basement membrane as well as the cellular crescents were immunostaining positive for WT1, p-S6, HIF1α, and Cxcr4. Furthermore, continuously administrating rapamycin starting at 7 wk of age for 5 wk abolished crescents as well as the induction of p-S6, HIF1α, and Cxcr4 in the glomeruli from the knockouts. Together, it is concluded that mTORC1 activation in podocytes promotes cellular crescent formation, and targeting this signaling may shed new light on the treatment of patients with crescentic glomerular diseases.
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Affiliation(s)
- Junhua Mao
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Zhifeng Zeng
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Zhuo Xu
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Jiangzhong Li
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Lei Jiang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Yi Fang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Xianlin Xu
- Department of Urology, 1st People's Hospital of Changzhou, Changzhou, China; and
| | - Zhangxue Hu
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
| | - Weichun He
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Junwei Yang
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Chunsun Dai
- Center for Kidney Disease, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China; State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing, China;
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Yanagisawa N, Hana K, Nakada N, Ichinoe M, Koizumi W, Endou H, Okayasu I, Murakumo Y. High expression of L-type amino acid transporter 1 as a prognostic marker in bile duct adenocarcinomas. Cancer Med 2014; 3:1246-55. [PMID: 24890221 PMCID: PMC4302674 DOI: 10.1002/cam4.272] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 04/02/2014] [Accepted: 04/20/2014] [Indexed: 12/21/2022] Open
Abstract
Oncocytic L-type amino acid transporter (LAT) 1 may be a prognostic indicator and target of new molecular therapeutic agents against malignancies. To investigate whether LAT1 expression influence the outcomes of patients with bile duct cancer, the expression of LAT1, LAT2, CD98, and Ki-67 was investigated immunohistochemically in 134 surgically resected bile duct adenocarcinomas, including 84 distal extrahepatic bile duct adenocarcinomas, 21 hilar cholangiocarcinomas, 15 intrahepatic cholangiocarcinomas, and 14 ampullary adenocarcinomas. LAT1 expression was weakly correlated with CD98 expression and Ki-67 labeling index (LI). Kaplan–Meier analysis showed a significant difference in prognosis between patients with bile duct adenocarcinomas having LAT1-high and -low scores, whereas LAT2 and CD98 expression and Ki-67 LI were not predictive of poor prognosis. Prognosis tended to be worse in patients having tumors with LAT1-high/LAT2-low than LAT1-low/LAT2-high scores (P = 0.0686). Multivariable analyses revealed that LAT1 expression, surgical margin, pT stage were independent prognostic factors. In conclusion, aberrant overexpression of LAT1 in bile duct adenocarcinoma predicts poor prognosis, suggesting that LAT1 may be a potential target of anticancer therapy.
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Affiliation(s)
- Nobuyuki Yanagisawa
- Department of Pathology, Kitasato University School of Medicine, Kanagawa, 252-0374, Japan; Department of Pathology of Biological Responses, Kitasato University Graduate School of Medical Science, Kanagawa, 252-0374, Japan
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Shankland SJ, Smeets B, Pippin JW, Moeller MJ. The emergence of the glomerular parietal epithelial cell. Nat Rev Nephrol 2014; 10:158-73. [PMID: 24468766 DOI: 10.1038/nrneph.2014.1] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glomerular diseases are the leading causes of chronic and end-stage kidney disease. In the 1980s and 1990s, attention was focused on the biology and role of glomerular endothelial and mesangial cells. For the past two decades, seminal discoveries have been made in podocyte biology in health and disease. More recently, the glomerular parietal epithelial cell (PEC)-the fourth resident glomerular cell type-has been under active study, leading to a better understanding and definition of how these cells behave normally, and their potential roles in glomerular disease. Accordingly, this Review will focus on our current knowledge of PECs, in both health and disease. We discuss model systems to study PECs, how PECs might contribute to glomerulosclerosis, crescent and pseudocrescent formation and how PECs handle filtered albumin. These events have consequences on PEC structure and function, and PECs have potential roles as stem or progenitor cells for podocytes in glomerular regeneration, which will also be described.
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Affiliation(s)
- Stuart J Shankland
- Division of Nephrology, University of Washington, 1959 North East Pacific Avenue, Box 356521, Room BB1269, Seattle, WA 98195-6521, USA
| | - Bart Smeets
- Nephrology and Clinical Immunology, University Hospital of the RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, 1959 North East Pacific Avenue, Box 356521, Room BB1269, Seattle, WA 98195-6521, USA
| | - Marcus J Moeller
- Nephrology and Clinical Immunology, University Hospital of the RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
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Increased expression of system large amino acid transporter (LAT)-1 mRNA is associated with invasive potential and unfavorable prognosis of human clear cell renal cell carcinoma. BMC Cancer 2013; 13:509. [PMID: 24168110 PMCID: PMC3832879 DOI: 10.1186/1471-2407-13-509] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 10/28/2013] [Indexed: 12/22/2022] Open
Abstract
Background The system L amino acid transporter (LAT) has an important role in the transport of various amino acids, and there have been reports about the relation of this system to cancer. Although LATs are highly expressed in the kidneys, little is known about their influence on human renal cancer. Methods To clarify the role of LATs in human clear cell renal cell carcinoma (RCC), we investigated the expression of mRNAs for LAT1, LAT2, LAT3, LAT4, and 4F2hc in clear cell RCC tissues. The mRNAs of these five genes were analyzed by the real-time reverse transcription polymerase chain reaction in matched sets of tumor and non-tumor tissues obtained at operation from 82 Japanese patients with clear cell RCC. We also measured phosphorylated S6 ribosomal protein (Ser-235/236) proteins levels in 18 paired tumor and non-tumor tissues of the patients by Western blotting. Results Expression of LAT1 mRNA was significantly increased in tumor tissue compared with non-tumor tissue, while expression of LAT2 and LAT3 mRNAs was reduced. There was no difference in the expression of LAT4 and 4F2hc mRNAs between tumor and non-tumor tissues. Increased expression of LAT1 mRNA was associated with less differentiated tumors, local invasion, microscopic vascular invasion, and metastasis. Kaplan-Meier survival analysis showed that a higher serum LAT1 mRNA level was associated with a shorter overall survival time. Phosphorylated S6 ribosomal protein levels were associated with metastatic potential. LAT1 mRNA levels positively correlated with phosphorylated S6 ribosomal protein proteins levels in primary tumors. Conclusions These findings suggest that LAT1 mRNA is related to the invasive and progressive potential of clear cell RCC.
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The SLC3 and SLC7 families of amino acid transporters. Mol Aspects Med 2013; 34:139-58. [PMID: 23506863 DOI: 10.1016/j.mam.2012.10.007] [Citation(s) in RCA: 467] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/15/2012] [Indexed: 01/18/2023]
Abstract
Amino acids are necessary for all living cells and organisms. Specialized transporters mediate the transfer of amino acids across plasma membranes. Malfunction of these proteins can affect whole-body homoeostasis giving raise to diverse human diseases. Here, we review the main features of the SLC3 and SLC7 families of amino acid transporters. The SLC7 family is divided into two subfamilies, the cationic amino acid transporters (CATs), and the L-type amino acid transporters (LATs). The latter are the light or catalytic subunits of the heteromeric amino acid transporters (HATs), which are associated by a disulfide bridge with the heavy subunits 4F2hc or rBAT. These two subunits are glycoproteins and form the SLC3 family. Most CAT subfamily members were functionally characterized and shown to function as facilitated diffusers mediating the entry and efflux of cationic amino acids. In certain cells, CATs play an important role in the delivery of L-arginine for the synthesis of nitric oxide. HATs are mostly exchangers with a broad spectrum of substrates and are crucial in renal and intestinal re-absorption and cell redox balance. Furthermore, the role of the HAT 4F2hc/LAT1 in tumor growth and the application of LAT1 inhibitors and PET tracers for reduction of tumor progression and imaging of tumors are discussed. Finally, we describe the link between specific mutations in HATs and the primary inherited aminoacidurias, cystinuria and lysinuric protein intolerance.
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Imasawa T, Rossignol R. Podocyte energy metabolism and glomerular diseases. Int J Biochem Cell Biol 2013; 45:2109-18. [PMID: 23806869 DOI: 10.1016/j.biocel.2013.06.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 06/10/2013] [Accepted: 06/14/2013] [Indexed: 11/16/2022]
Abstract
Mitochondria are crucial organelles that produce and deliver adenosine triphosphate (ATP), by which all cellular processes are driven. Although the mechanisms that control mitochondrial biogenesis, function and dynamics are complex process and vary among different cell types, recent studies provided many new discoveries in this field. Podocyte injury is a crucial step in the development of a large number of glomerular diseases. Glomerular podocytes are unique cells with complex foot processes that cover the outer layer of the glomerular basement membrane, and are the principle cells composing filtration barriers of glomerular capillaries. Little is known on the modalities and the regulation of podocyte's energetics as well as the type of energy substrate primarily used for their activity, recent studies revealed that dysfunction of energy transduction in podocytes may underlie the podocyte injury associated with numerous glomerular diseases. We herein review and discuss the importance of a fine regulation of energy metabolism in podocytes for maintaining their cellular structure and related kidney function. In the future, understanding these mechanisms will open up new areas of treatment for glomerular diseases.
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Rozen-Zvi B, Hayashida T, Hubchak SC, Hanna C, Platanias LC, Schnaper HW. TGF-β/Smad3 activates mammalian target of rapamycin complex-1 to promote collagen production by increasing HIF-1α expression. Am J Physiol Renal Physiol 2013; 305:F485-94. [PMID: 23761672 DOI: 10.1152/ajprenal.00215.2013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Transforming growth factor (TGF)-β is a major mediator of kidney fibrosis. In the past decade it was recognized that, besides canonical Smad signaling, many other signaling pathways participate in the process of TGF-β-induced fibrogenesis. One such pathway involves mammalian target of rapamycin complex (mTORC)1. We recently reported that the hypoxia-inducible factor (HIF)-1 is essential for TGF-β-induced collagen expression regardless of ambient oxygen tension. A modulator of HIF expression other than oxygen tension is mTORC1. We therefore sought to evaluate a possible role for mTORC1 activity in TGF-β-induced fibrogenesis. mTORC1 activity was increased in human mesangial cells treated with TGF-β in a TGF-β receptor-dependent manner. Short hairpin (sh)RNA to Smad3 decreased, while overexpression of Smad3 increased, the mTORC1 activity, suggesting that TGF-β stimulation of mTORC1 also requires Smad3. Pretreatment with rapamycin or shRNA for a regulatory molecule of mTORC1, Raptor, reduced TGF-β-induced COL1A2-luc activity and collagen I protein expression. mTORC1 inhibition also prevented the TGF-β-stimulated increase in both hypoxia-responsive element (HRE) activity and HIF-1α protein expression, while activation of mTORC1 by active Rheb increased basal but not TGF-β-induced HRE activity. shRNA to Smad3 reduced HRE activity, while overexpression of Smad3 increased HIF-1α protein expression and activity in an mTORC1-dependent manner. Lastly, overexpression of HIF-1α bypassed the inhibitory effect of mTORC1 blockade on collagen expression. These results suggest that Smad3/mTORC1 interaction to promote HIF-1 expression is a key step in normoxic kidney fibrogenesis.
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Atypical deletion in Williams-Beuren syndrome critical region detected by MLPA in a patient with supravalvular aortic stenosis and learning difficulty. J Genet Genomics 2012; 39:571-4. [PMID: 23089367 DOI: 10.1016/j.jgg.2012.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 06/23/2012] [Accepted: 07/09/2012] [Indexed: 12/25/2022]
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Khunweeraphong N, Nagamori S, Wiriyasermkul P, Nishinaka Y, Wongthai P, Ohgaki R, Tanaka H, Tominaga H, Sakurai H, Kanai Y. Establishment of stable cell lines with high expression of heterodimers of human 4F2hc and human amino acid transporter LAT1 or LAT2 and delineation of their differential interaction with α-alkyl moieties. J Pharmacol Sci 2012; 119:368-80. [PMID: 22850614 PMCID: PMC7128428 DOI: 10.1254/jphs.12124fp] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
System L is a major transport system for cellular uptake of neutral amino acids. Among system L transporters, L-type amino acid transporter 1 (LAT1) is responsible for the nutrient uptake in cancer cells, whereas L-type amino acid transporter 2 (LAT2) is a transporter for non-cancer cells. In this study, we have established HEK293 cell lines stably expressing high levels of human LAT1 and LAT2 forming heterodimers with native human 4F2hc of the cells. We have found that l-[14C]alanine is an appropriate substrate to examine the function of LAT2, whereas l-[14C]leucine is used for LAT1. By using l-[14C]alanine on LAT2, we have for the first time directly evaluated the function of human LAT2 expressed in mammalian cells and obtained its reliable kinetics. Using α-alkyl amino acids including α-methyl-alanine and α-ethyl-l-alanine, we have demonstrated that α-alkyl groups interfere with the interaction with LAT2. These cell lines with higher practical advantages would be useful for screening and analyzing compounds to develop LAT1-specific drugs that can be used for cancer diagnosis and therapeutics. The strategy that we took to establish the cell lines would also be applicable to the other heterodimeric transporters with important therapeutic implications.
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Affiliation(s)
- Narakorn Khunweeraphong
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Japan
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Understanding the mechanisms of proteinuria: therapeutic implications. Int J Nephrol 2012; 2012:546039. [PMID: 22844592 PMCID: PMC3398673 DOI: 10.1155/2012/546039] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/30/2012] [Indexed: 12/18/2022] Open
Abstract
A large body of evidence indicates that proteinuria is a strong predictor of morbidity, a cause of inflammation, oxidative stress and progression of chronic kidney disease, and development of cardiovascular disease. The processes that lead to proteinuria are complex and involve factors such as glomerular hemodynamic, tubular absorption, and diffusion gradients. Alterations in various different molecular pathways and interactions may lead to the identical clinical end points of proteinuria and chronic kidney disease. Glomerular diseases include a wide range of immune and nonimmune insults that may target and thus damage some components of the glomerular filtration barrier. In many of these conditions, the renal visceral epithelial cell (podocyte) responds to injury along defined pathways, which may explain the resultant clinical and histological changes. The recent discovery of the molecular components of the slit diaphragm, specialized structure of podocyte-podocyte interaction, has been a major breakthrough in understanding the crucial role of the epithelial layer of the glomerular barrier and the pathogenesis of proteinuria. This paper provides an overview and update on the structure and function of the glomerular filtration barrier and the pathogenesis of proteinuria, highlighting the role of the podocyte in this setting. In addition, current antiproteinuric therapeutic approaches are briefly commented.
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Abundance of amino acid transporters involved in mTORC1 activation in skeletal muscle of neonatal pigs is developmentally regulated. Amino Acids 2012; 45:523-30. [PMID: 22643846 DOI: 10.1007/s00726-012-1326-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 05/15/2012] [Indexed: 01/22/2023]
Abstract
Previously we demonstrated that the insulin- and amino acid-induced activation of the mammalian target of rapamycin complex 1 (mTORC1) is developmentally regulated in neonatal pigs. Recent studies have indicated that members of the System A transporter (SNAT2), the System N transporter (SNAT3), the System L transporters (LAT1 and LAT2), and the proton-assisted amino acid transporters (PAT1 and PAT2) have crucial roles in the activation of mTORC1 and that the abundance of amino acid transporters is positively correlated with their activation. This study aimed to determine the effect of the post-prandial rise in insulin and amino acids on the abundance or activation of SNAT2, SNAT3, LAT1, LAT2, PAT1, and PAT2 and whether the response is modified by development. Overnight fasted 6- and 26-day-old pigs were infused for 2 h with saline (Control) or with insulin or amino acids to achieve fed levels while amino acids or insulin, respectively, as well as glucose were maintained at fasting levels. The abundance of SNAT2, SNAT3, LAT1, LAT2, PAT1, and PAT2 was higher in muscle of 6- compared with 26-day-old pigs. The abundance of the PAT2-mTOR complex was greater in 6- than in 26-day-old pigs, consistent with the higher activation of mTORC1. Neither insulin nor amino acids altered amino acid transporter or PAT2-mTOR complex abundance. In conclusion, the amino acid transporters, SNAT 2/3, LAT 1/2, and PAT1/2, likely have important roles in the enhanced amino acid-induced activation of mTORC1 in skeletal muscle of the neonate.
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Yan K, Ito N, Nakajo A, Kurayama R, Fukuhara D, Nishibori Y, Kudo A, Akimoto Y, Takenaka H. The struggle for energy in podocytes leads to nephrotic syndrome. Cell Cycle 2012; 11:1504-11. [PMID: 22433955 DOI: 10.4161/cc.19825] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Podocytes are terminally differentiated post-mitotic cells similar to neurons, and their damage leads to nephrotic syndrome, which is characterized by massive proteinuria associated with generalized edema. A recent functional genetic approach has identified the pathological relevance of several mutated proteins in glomerular podocytes to the mechanism of proteinuria in hereditary nephrotic syndrome. In contrast, the pathophysiology of acquired primary nephrotic syndrome, including minimal change disease, is still largely unknown. We recently demonstrated the possible linkage of an energy-consuming process in glomerular podocytes to the mechanism of proteinuria. Puromycin aminonucleoside nephrosis, a rat model of minimal change disease, revealed the activation of the unfolded protein response (UPR) in glomerular podocytes to be a cause of proteinuria. The pretreatment of puromycin aminonucleoside rat podocytes and cultured podocytes with the mammalian target of rapamycin (mTOR) inhibitor everolimus further revealed that mTOR complex 1 consumed energy, which was followed by UPR activation. In this paper, we will review nutritional transporters to summarize the energy uptake process in podocytes and review the involvement of the UPR in the pathogenesis of glomerular diseases. We will also present additional data that reveal how mTOR complex 1 acts upstream of the UPR. Finally, we will discuss the potential significance of targeting the energy metabolism of podocytes to develop new therapeutic interventions for acquired nephrotic syndrome.
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Affiliation(s)
- Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan.
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mTORC1 activation triggers the unfolded protein response in podocytes and leads to nephrotic syndrome. J Transl Med 2011; 91:1584-95. [PMID: 21876538 DOI: 10.1038/labinvest.2011.135] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Although podocyte damage is known to be responsible for the development of minimal-change disease (MCD), the underlying mechanism remains to be elucidated. Previously, using a rat MCD model, we showed that endoplasmic reticulum (ER) stress in the podocytes was associated with the heavy proteinuric state and another group reported that a mammalian target of rapamycin complex 1 (mTORC1) inhibitor protected against proteinuria. In this study, which utilized a rat MCD model, a combination of immunohistochemistry, dual immunofluorescence and confocal microscopy, western blot analysis, and quantitative real-time RT-PCR revealed co-activation of the unfolded protein response (UPR), which was induced by ER stress, and mTORC1 in glomerular podocytes before the onset of proteinuria and downregulation of nephrin at the post-translational level at the onset of proteinuria. Podocyte culture experiments revealed that mTORC1 activation preceded the UPR that was associated with a marked decrease in the energy charge. The mTORC1 inhibitor everolimus completely inhibited proteinuria through a reduction in both mTORC1 and UPR activity and preserved nephrin expression in the glomerular podocytes. In conclusion, mTORC1 activation may perturb the regulatory system of energy metabolism primarily by promoting energy consumption and inducing the UPR, which underlie proteinuria in MCD.
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