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Bao L, Fu L, Su Y, Chen Z, Peng Z, Sun L, Gonzalez FJ, Wu C, Zhang H, Shi B, Shi YB. Amino acid transporter SLC7A5 regulates cell proliferation and secretary cell differentiation and distribution in the mouse intestine. Int J Biol Sci 2024; 20:2187-2201. [PMID: 38617535 PMCID: PMC11008275 DOI: 10.7150/ijbs.94297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 02/16/2024] [Indexed: 04/16/2024] Open
Abstract
The intestine is critical for not only processing nutrients but also protecting the organism from the environment. These functions are mainly carried out by the epithelium, which is constantly being self-renewed. Many genes and pathways can influence intestinal epithelial cell proliferation. Among them is mTORC1, whose activation increases cell proliferation. Here, we report the first intestinal epithelial cell (IEC)-specific knockout (ΔIEC) of an amino acid transporter capable of activating mTORC1. We show that the transporter, SLC7A5, is highly expressed in mouse intestinal crypt and Slc7a5ΔIEC reduces mTORC1 signaling. Surprisingly, adult Slc7a5ΔIEC intestinal crypts have increased cell proliferation but reduced mature Paneth cells. Goblet cells, the other major secretory cell type in the small intestine, are increased in the crypts but reduced in the villi. Analyses with scRNA-seq and electron microscopy have revealed dedifferentiation of Paneth cells in Slc7a5ΔIEC mice, leading to markedly reduced secretory granules with little effect on Paneth cell number. Thus, SLC7A5 likely regulates secretory cell differentiation to affect stem cell niche and indirectly regulate cell proliferation.
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Affiliation(s)
- Lingyu Bao
- Section on Molecular Morphogenesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, MD, USA
- Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine. No.277, Yanta West Road, Xi'an, Shaanxi, 710061, P.R. China
| | - Liezhen Fu
- Section on Molecular Morphogenesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, MD, USA
| | - Yijun Su
- Laboratory of High Resolution Optical Imaging and Advanced Imaging and Microscopy Resource, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
- Janelia Research Campus, Howard Hughes Medical Institute (HHMI), Ashburn, VA, USA
| | - Zuojia Chen
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhaoyi Peng
- Section on Molecular Morphogenesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, MD, USA
- Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine. No.277, Yanta West Road, Xi'an, Shaanxi, 710061, P.R. China
| | - Lulu Sun
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Frank J. Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chuan Wu
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongen Zhang
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Bingyin Shi
- Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine. No.277, Yanta West Road, Xi'an, Shaanxi, 710061, P.R. China
| | - Yun-Bo Shi
- Section on Molecular Morphogenesis, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, MD, USA
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2
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Ng D, Pawling J, Dennis JW. Gene purging and the evolution of Neoave metabolism and longevity. J Biol Chem 2023; 299:105409. [PMID: 37918802 PMCID: PMC10722388 DOI: 10.1016/j.jbc.2023.105409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/19/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023] Open
Abstract
Maintenance of the proteasome requires oxidative phosphorylation (ATP) and mitigation of oxidative damage, in an increasingly dysfunctional relationship with aging. SLC3A2 plays a role on both sides of this dichotomy as an adaptor to SLC7A5, a transporter of branched-chain amino acids (BCAA: Leu, Ile, Val), and to SLC7A11, a cystine importer supplying cysteine to the synthesis of the antioxidant glutathione. Endurance in mammalian muscle depends in part on oxidation of BCAA; however, elevated serum levels are associated with insulin resistance and shortened lifespans. Intriguingly, the evolution of modern birds (Neoaves) has entailed the purging of genes including SLC3A2, SLC7A5, -7, -8, -10, and SLC1A4, -5, largely removing BCAA exchangers and their interacting Na+/Gln symporters in pursuit of improved energetics. Additional gene purging included mitochondrial BCAA aminotransferase (BCAT2), pointing to reduced oxidation of BCAA and increased hepatic conversion to triglycerides and glucose. Fat deposits are anhydrous and highly reduced, maximizing the fuel/weight ratio for prolonged flight, but fat accumulation in muscle cells of aging humans contributes to inflammation and senescence. Duplications of the bidirectional α-ketoacid transporters SLC16A3, SLC16A7, the cystine transporters SLC7A9, SLC7A11, and N-glycan branching enzymes MGAT4B, MGAT4C in Neoaves suggests a shift to the transport of deaminated essential amino acid, and stronger mitigation of oxidative stress supported by the galectin lattice. We suggest that Alfred Lotka's theory of natural selection as a maximum power organizer (PNAS 8:151,1922) made an unusually large contribution to Neoave evolution. Further molecular analysis of Neoaves may reveal novel rewiring with applications for human health and longevity.
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Affiliation(s)
- Deanna Ng
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Judy Pawling
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - James W Dennis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto Ontario, Canada.
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3
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Xia P, Dubrovska A. CD98 heavy chain as a prognostic biomarker and target for cancer treatment. Front Oncol 2023; 13:1251100. [PMID: 37823053 PMCID: PMC10562705 DOI: 10.3389/fonc.2023.1251100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 08/29/2023] [Indexed: 10/13/2023] Open
Abstract
The SLC3A2 gene encodes for a cell-surface transmembrane protein CD98hc (4F2). CD98hc serves as a chaperone for LAT1 (SLC7A5), LAT2 (SLC7A8), y+LAT1 (SLC7A7), y+LAT2 (SLC7A6), xCT (SLC7A11) and Asc1 (SLC7A10) providing their recruitment to the plasma membrane. Together with the light subunits, it constitutes heterodimeric transmembrane amino acid transporters. CD98hc interacts with other surface molecules, such as extracellular matrix metalloproteinase inducer CD147 (EMMPRIN) and adhesion receptors integrins, and regulates glucose uptake. In this way, CD98hc connects the signaling pathways sustaining cell proliferation and migration, biosynthesis and antioxidant defense, energy production, and stem cell properties. This multifaceted role makes CD98hc one of the critical regulators of tumor growth, therapy resistance, and metastases. Indeed, the high expression levels of CD98hc were confirmed in various tumor tissues, including head and neck squamous cell carcinoma, glioblastoma, colon adenocarcinoma, pancreatic ductal adenocarcinoma, and others. A high expression of CD98hc has been linked to clinical prognosis and response to chemo- and radiotherapy in several types of cancer. In this mini-review, we discuss the physiological functions of CD98hc, its role in regulating tumor stemness, metastases, and therapy resistance, and the clinical significance of CD98hc as a tumor marker and therapeutic target.
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Affiliation(s)
- Pu Xia
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Anna Dubrovska
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology-OncoRay, Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden and German Cancer Research Center (DKFZ), Heidelberg, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden: German Cancer Research Center (DKFZ), Heidelberg, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany
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4
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Canup BSB, Song H, Laroui H. Role of CD98 in liver disease. Ann Hepatol 2021; 19:602-607. [PMID: 32057700 DOI: 10.1016/j.aohep.2019.11.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 02/08/2023]
Abstract
CD98 is a multifunctional glycoprotein that is involved in various biological processes such as amino acid transport, cell adhesion, diffusion, adhesion, and proliferation. The role of CD98 in liver disease has not thoroughly been examined and is limited reports in the literature. Among these reports, direct association for CD98 in nonalcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC) have been reported. Our lab has reported that targeting CD98 in high fat diet mice reduced steatosis and inflammation in NAFLD. Other reports associate CD98 in HCC due in part to the role of CD98 in activating integrin signaling. Herein, we present CD98 staining on liver biopsies from NAFLD, chronic active hepatitis, cirrhosis, and 3 stages of HCC to demonstrate the upregulation of CD98 expression throughout liver disease progression. In addition, we analyze current literature to elucidate roles and potential roles of CD98 with each stage of liver disease.
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Affiliation(s)
- Brandon S B Canup
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA, USA
| | - Heliang Song
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA, USA
| | - Hamed Laroui
- Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA, USA; Department of Biology, Center for Diagnostics and Therapeutics, Georgia State University, 145 Piedmont Ave SE, Atlanta, GA, USA.
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5
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Zhang J, Xu Y, Li D, Fu L, Zhang X, Bao Y, Zheng L. Review of the Correlation of LAT1 With Diseases: Mechanism and Treatment. Front Chem 2020; 8:564809. [PMID: 33195053 PMCID: PMC7606929 DOI: 10.3389/fchem.2020.564809] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/17/2020] [Indexed: 12/17/2022] Open
Abstract
LAT1 is a member of the system L transporter family. The main role of the LAT1 is to transport specific amino acids through cell membranes to provide nutrients to cells and participate in several metabolic pathways. It also contributes to the transport of hormones and some drugs, which are essential for the development and treatment of some diseases. In recent years, many studies have shown that LAT1 is related to cancer, obesity, diabetes, and other diseases. However, the specific mechanism underlying the influence of LAT1 on such conditions remains unclear. Through the increasing number of studies on LAT1, we have obtained a preliminary understanding on the function of LAT1 in diseases. These studies also provide a theoretical basis for finding treatments for LAT1-related diseases, such as cancer. This review summarizes the function and mechanism of LAT1 in different diseases and the treatment of LAT1-related diseases. It also provides support for the development of novel and reliable disease treatments.
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Affiliation(s)
- Jingshun Zhang
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Ying Xu
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Dandan Li
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Lulu Fu
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Xueying Zhang
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Yigang Bao
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
| | - Lianwen Zheng
- Reproductive Medical Center, Department of Obstetrics and Gynecology, The Second Hospital of Jilin University, Changchun, China
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6
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Xu J, Jiang C, Cai Y, Guo Y, Wang X, Zhang J, Xu J, Xu K, Zhu W, Wang S, Zhang F, Geng M, Han Y, Ning Q, Xu P, Meng L, Lu S. Intervening upregulated SLC7A5 could mitigate inflammatory mediator by mTOR-P70S6K signal in rheumatoid arthritis synoviocytes. Arthritis Res Ther 2020; 22:200. [PMID: 32867828 PMCID: PMC7457370 DOI: 10.1186/s13075-020-02296-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 08/19/2020] [Indexed: 12/12/2022] Open
Abstract
Objective The disruption of metabolic events and changes to nutrient and oxygen availability due to sustained inflammation in RA increases the demand of bioenergetic and biosynthetic processes within the damaged tissue. The current study aimed to understand the molecular mechanisms of SLC7A5 (amino acid transporter) in synoviocytes of RA patients. Methods Synovial tissues were obtained from OA and RA patients. Fibroblast-like synoviocytes (FLS) were isolated, and SLC7A5 expression was examined by using RT-qPCR, immunofluorescence, and Western blotting. RNAi and antibody blocking treatments were used to knockdown SLC7A5 expression or to block its transporter activities. mTOR activity assay and MMP expression levels were monitored in RA FLS under amino acid deprivation or nutrient-rich conditions. Results RA FLS displayed significantly upregulated expression of SLC7A5 compared to OA FLS. Cytokine IL-1β was found to play a crucial role in upregulating SLC7A5 expression via the NF-κB pathway. Intervening SLC7A5 expression with RNAi or blocking its function by monoclonal antibody ameliorated MMP3 and MMP13 protein expression. Conversely, upregulation of SLC7A5 or tryptophan supplementation enhanced mTOR-P70S6K signals which promoted the protein translation of MMP3 and MMP13 in RA FLS. Conclusion Activated NF-κB pathway upregulates SLC7A5, which enhances the mTOR-P70S6K activity and MMP3 and MMP13 expression in RA FLS.
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Affiliation(s)
- Jing Xu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Congshan Jiang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Yongsong Cai
- Department of Joint Surgery, Xi'an Hong Hui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Yuanxu Guo
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Xipeng Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Jiaxiang Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Jiawen Xu
- Department of Joint Surgery, Xi'an Hong Hui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Ke Xu
- Department of Joint Surgery, Xi'an Hong Hui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Wenhua Zhu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Si Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Fujun Zhang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Manman Geng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Yan Han
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Qilan Ning
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Peng Xu
- Department of Joint Surgery, Xi'an Hong Hui Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Liesu Meng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Shemin Lu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China. .,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China.
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7
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Poncet N, Halley PA, Lipina C, Gierliński M, Dady A, Singer GA, Febrer M, Shi Y, Yamaguchi TP, Taylor PM, Storey KG. Wnt regulates amino acid transporter Slc7a5 and so constrains the integrated stress response in mouse embryos. EMBO Rep 2020; 21:e48469. [PMID: 31789450 PMCID: PMC6944906 DOI: 10.15252/embr.201948469] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 10/18/2019] [Accepted: 10/25/2019] [Indexed: 12/29/2022] Open
Abstract
Amino acids are essential for cellular metabolism, and it is important to understand how nutrient supply is coordinated with changing energy requirements during embryogenesis. Here, we show that the amino acid transporter Slc7a5/Lat1 is highly expressed in tissues undergoing morphogenesis and that Slc7a5-null mouse embryos have profound neural and limb bud outgrowth defects. Slc7a5-null neural tissue exhibited aberrant mTORC1 activity and cell proliferation; transcriptomics, protein phosphorylation and apoptosis analyses further indicated induction of the integrated stress response as a potential cause of observed defects. The pattern of stress response gene expression induced in Slc7a5-null embryos was also detected at low level in wild-type embryos and identified stress vulnerability specifically in tissues undergoing morphogenesis. The Slc7a5-null phenotype is reminiscent of Wnt pathway mutants, and we show that Wnt/β-catenin loss inhibits Slc7a5 expression and induces this stress response. Wnt signalling therefore normally supports the metabolic demands of morphogenesis and constrains cellular stress. Moreover, operation in the embryo of the integrated stress response, which is triggered by pathogen-mediated as well as metabolic stress, may provide a mechanistic explanation for a range of developmental defects.
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Affiliation(s)
- Nadège Poncet
- Division of Cell & Developmental BiologySchool of Life SciencesUniversity of DundeeDundeeUK
- Present address:
Institute of PhysiologyUniversity of ZürichZürichSwitzerland
| | - Pamela A Halley
- Division of Cell & Developmental BiologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Christopher Lipina
- Division of Cell Signalling and ImmunologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Marek Gierliński
- Division of Computational BiologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Alwyn Dady
- Division of Cell & Developmental BiologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Gail A Singer
- Division of Cell & Developmental BiologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Melanie Febrer
- Sequencing FacilitySchool of Life SciencesUniversity of DundeeDundeeUK
- Present address:
Illumina CanadaVictoriaBCCanada
| | - Yun‐Bo Shi
- Section on Molecular MorphogenesisNICHD, NIHBethesdaMDUSA
| | - Terry P Yamaguchi
- Cancer and Developmental Biology LaboratoryCenter for Cancer ResearchNational Cancer Institute‐Frederick, NIHFrederickMDUSA
| | - Peter M Taylor
- Division of Cell Signalling and ImmunologySchool of Life SciencesUniversity of DundeeDundeeUK
| | - Kate G Storey
- Division of Cell & Developmental BiologySchool of Life SciencesUniversity of DundeeDundeeUK
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8
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Poncet N, Mitchell FE, Ibrahim AFM, McGuire VA, English G, Arthur JSC, Shi YB, Taylor PM. The catalytic subunit of the system L1 amino acid transporter (slc7a5) facilitates nutrient signalling in mouse skeletal muscle. PLoS One 2014; 9:e89547. [PMID: 24586861 PMCID: PMC3935884 DOI: 10.1371/journal.pone.0089547] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/22/2014] [Indexed: 01/13/2023] Open
Abstract
The System L1-type amino acid transporter mediates transport of large neutral amino acids (LNAA) in many mammalian cell-types. LNAA such as leucine are required for full activation of the mTOR-S6K signalling pathway promoting protein synthesis and cell growth. The SLC7A5 (LAT1) catalytic subunit of high-affinity System L1 functions as a glycoprotein-associated heterodimer with the multifunctional protein SLC3A2 (CD98). We generated a floxed Slc7a5 mouse strain which, when crossed with mice expressing Cre driven by a global promoter, produced Slc7a5 heterozygous knockout (Slc7a5+/−) animals with no overt phenotype, although homozygous global knockout of Slc7a5 was embryonically lethal. Muscle-specific (MCK Cre-mediated) Slc7a5 knockout (MS-Slc7a5-KO) mice were used to study the role of intracellular LNAA delivery by the SLC7A5 transporter for mTOR-S6K pathway activation in skeletal muscle. Activation of muscle mTOR-S6K (Thr389 phosphorylation) in vivo by intraperitoneal leucine injection was blunted in homozygous MS-Slc7a5-KO mice relative to wild-type animals. Dietary intake and growth rate were similar for MS-Slc7a5-KO mice and wild-type littermates fed for 10 weeks (to age 120 days) with diets containing 10%, 20% or 30% of protein. In MS-Slc7a5-KO mice, Leu and Ile concentrations in gastrocnemius muscle were reduced by ∼40% as dietary protein content was reduced from 30 to 10%. These changes were associated with >50% decrease in S6K Thr389 phosphorylation in muscles from MS-Slc7a5-KO mice, indicating reduced mTOR-S6K pathway activation, despite no significant differences in lean tissue mass between groups on the same diet. MS-Slc7a5-KO mice on 30% protein diet exhibited mild insulin resistance (e.g. reduced glucose clearance, larger gonadal adipose depots) relative to control animals. Thus, SLC7A5 modulates LNAA-dependent muscle mTOR-S6K signalling in mice, although it appears non-essential (or is sufficiently compensated by e.g. SLC7A8 (LAT2)) for maintenance of normal muscle mass.
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Affiliation(s)
- Nadège Poncet
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Fiona E. Mitchell
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
- Section on Molecular Morphogenesis, Program in Cellular Regulation and Metabolism (PCRM), NICHD, NIH, Bethesda, Maryland, United States of America
| | - Adel F. M. Ibrahim
- Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Victoria A. McGuire
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Grant English
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - J. Simon C Arthur
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Yun-Bo Shi
- Section on Molecular Morphogenesis, Program in Cellular Regulation and Metabolism (PCRM), NICHD, NIH, Bethesda, Maryland, United States of America
- * E-mail: (Y-BS); (PMT)
| | - Peter M. Taylor
- Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee, United Kingdom
- * E-mail: (Y-BS); (PMT)
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9
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Sinclair LV, Rolf J, Emslie E, Shi YB, Taylor PM, Cantrell DA. Control of amino-acid transport by antigen receptors coordinates the metabolic reprogramming essential for T cell differentiation. Nat Immunol 2013; 14:500-8. [PMID: 23525088 PMCID: PMC3672957 DOI: 10.1038/ni.2556] [Citation(s) in RCA: 648] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 01/24/2013] [Indexed: 12/13/2022]
Abstract
T lymphocytes must regulate nutrient uptake to meet the metabolic demands of an immune response. Here we show that the intracellular supply of large neutral amino acids (LNAAs) in T cells was regulated by pathogens and the T cell antigen receptor (TCR). T cells responded to antigen by upregulating expression of many amino-acid transporters, but a single System L ('leucine-preferring system') transporter, Slc7a5, mediated uptake of LNAAs in activated T cells. Slc7a5-null T cells were unable to metabolically reprogram in response to antigen and did not undergo clonal expansion or effector differentiation. The metabolic catastrophe caused by loss of Slc7a5 reflected the requirement for sustained uptake of the LNAA leucine for activation of the serine-threonine kinase complex mTORC1 and for expression of the transcription factor c-Myc. Control of expression of the System L transporter by pathogens is thus a critical metabolic checkpoint for T cells.
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Affiliation(s)
- Linda V Sinclair
- Division of Cell Signalling and Immunology, University of Dundee, Dundee, UK
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Intestinal epithelial CD98 directly modulates the innate host response to enteric bacterial pathogens. Infect Immun 2013; 81:923-34. [PMID: 23297381 DOI: 10.1128/iai.01388-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
CD98 is a type II transmembrane glycoprotein whose expression increases in intestinal epithelial cells (IECs) during intestinal inflammation. Enteropathogenic Escherichia coli (EPEC) is a food-borne human pathogen that attaches to IECs and injects effector proteins directly into the host cells, thus provoking an inflammatory response. In the present study, we investigated CD98 and EPEC interactions in vitro and ex vivo and examined FVB wild-type (WT) and villin-CD98 transgenic mice overexpressing human CD98 in IECs (hCD98 Tg mice) and infected with Citrobacter rodentium as an in vivo model. In vivo studies indicated that CD98 overexpression, localized to the apical domain of colonic cells, increased the attachment of C. rodentium in mouse colons and resulted in increased expression of proinflammatory markers and decreased expression of anti-inflammatory markers. The proliferative markers Ki-67 and cyclin D1 were significantly increased in the colonic tissue of C. rodentium-infected hCD98 Tg mice compared to that of WT mice. Ex vivo studies correlate with the in vivo data. Small interfering RNA (siRNA) studies with Caco2-BBE cells showed a decrease in adherence of EPEC to Caco2 cells in which CD98 expression was knocked down. In vitro surface plasmon resonance (SPR) experiments showed direct binding between recombinant hCD98 and EPEC/C. rodentium proteins. We also demonstrated that the partial extracellular loop of hCD98 was sufficient for direct binding to EPEC/C. rodentium. These findings demonstrate the importance of the extracellular loop of CD98 in the innate host defense response to intestinal infection by attaching and effacing (A/E) pathogens.
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FUKUMOTO S, HANAZONO K, KOMATSU T, IWANO H, KADOSAWA T, UCHIDE T. L-Type Amino Acid Transporter 1 (LAT1) Expression in Canine Mammary Gland Tumors. J Vet Med Sci 2013; 75:431-7. [DOI: 10.1292/jvms.12-0356] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Shinya FUKUMOTO
- Veterinary Internal Medicine, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
| | - Kiwamu HANAZONO
- Veterinary Internal Medicine, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
| | - Takahiro KOMATSU
- Veterinary Oncology, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
| | - Hidetomo IWANO
- Veterinary Biochemistry, Department of Basic Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
| | - Tsuyoshi KADOSAWA
- Veterinary Oncology, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
| | - Tsuyoshi UCHIDE
- Veterinary Internal Medicine, Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
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CD98 increases renal epithelial cell proliferation by activating MAPKs. PLoS One 2012; 7:e40026. [PMID: 22768207 PMCID: PMC3386947 DOI: 10.1371/journal.pone.0040026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 05/31/2012] [Indexed: 12/22/2022] Open
Abstract
CD98 heavy chain (CD98hc) is a multifunctional transmembrane spanning scaffolding protein whose extracellular domain binds with light chain amino acid transporters (Lats) to form the heterodimeric amino acid transporters (HATs). It also interacts with β1 and β3 integrins by its transmembrane and cytoplasmic domains. This interaction is proposed to be the mechanism whereby CD98 mediates cell survival and growth via currently undefined signaling pathways. In this study, we determined whether the critical function of CD98-dependent amino acid transport also plays a role in cell proliferation and defined the signaling pathways that mediate CD98-dependent proliferation of murine renal inner medullary collecting duct (IMCD) cells. We demonstrate that downregulating CD98hc expression resulted in IMCD cell death. Utilizing overexpression studies of CD98hc mutants that either lacked a cytoplasmic tail or were unable to bind to Lats we showed that CD98 increases serum-dependent cell proliferation by a mechanism that requires the CD98hc cytoplasmic tail. We further demonstrated that CD98-dependent amino acid transport increased renal tubular epithelial cell proliferation by a mechanism that does not require the CD98hc cytoplasmic tail. Both these mechanisms of increased renal tubular epithelial cell proliferation are mediated by Erk and p38 MAPK signaling. Although increased amino transport markedly activated mTor signaling, this pathway did not alter cell proliferation. Thus, these studies demonstrate that in IMCD cells, the cytoplasmic and extracellular domains of CD98hc regulate cell proliferation by distinct mechanisms that are mediated by common MAPK signaling pathways.
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Homeostatic and innate immune responses: role of the transmembrane glycoprotein CD98. Cell Mol Life Sci 2012; 69:3015-26. [PMID: 22460579 DOI: 10.1007/s00018-012-0963-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2011] [Revised: 02/14/2012] [Accepted: 03/12/2012] [Indexed: 12/11/2022]
Abstract
The transmembrane glycoprotein CD98 is a potential regulator of multiple functions, including integrin signaling and amino acid transport. Abnormal expression or function of CD98 and disruption of the interactions between CD98 and its binding partners result in defects in cell homeostasis and immune responses. Indeed, expression of CD98 has been correlated with diseases such as inflammation and tumor metastasis. Modulation of CD98 expression and/or function therefore represents a promising therapeutic strategy for the treatment and prevention of such pathologies. Herein, we review the role of CD98 with focus on its functional importance in homeostasis and immune responses, which could help to better understand the pathogenesis of CD98-associated diseases.
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