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Tettoni SD, Egri SB, Doxsey DD, Veinotte K, Ouch C, Chang JY, Song K, Xu C, Shen K. Structure of the Schizosaccharomyces pombe Gtr-Lam complex reveals evolutionary divergence of mTORC1-dependent amino acid sensing. Structure 2023; 31:1065-1076.e5. [PMID: 37453417 PMCID: PMC10529327 DOI: 10.1016/j.str.2023.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/14/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023]
Abstract
mTORC1 is a protein kinase complex that controls cellular growth in response to nutrient availability. Amino acid signals are transmitted toward mTORC1 via the Rag/Gtr GTPases and their upstream regulators. An important regulator is LAMTOR, which localizes Rag/Gtr on the lysosomal/vacuole membrane. In human cells, LAMTOR consists of five subunits, but in yeast, only three or four. Currently, it is not known how variation of the subunit stoichiometry may affect its structural organization and biochemical properties. Here, we report a 3.1 Å-resolution structural model of the Gtr-Lam complex in Schizosaccharomyces pombe. We found that SpGtr shares conserved architecture as HsRag, but the intersubunit communication that coordinates nucleotide loading on the two subunits differs. In contrast, SpLam contains distinctive structural features, but its GTP-specific GEF activity toward SpGtr is evolutionarily conserved. Our results revealed unique evolutionary paths of the protein components of the mTORC1 pathway.
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Affiliation(s)
- Steven D Tettoni
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Shawn B Egri
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Dylan D Doxsey
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Kristen Veinotte
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Jeng-Yih Chang
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Kangkang Song
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA; Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
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2
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Tsujimoto K, Takamatsu H, Kumanogoh A. The Ragulator complex: delving its multifunctional impact on metabolism and beyond. Inflamm Regen 2023; 43:28. [PMID: 37173755 PMCID: PMC10175929 DOI: 10.1186/s41232-023-00278-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 05/01/2023] [Indexed: 05/15/2023] Open
Abstract
Our understanding of lysosomes has undergone a significant transformation in recent years, from the view that they are static organelles primarily responsible for the disposal and recycling of cellular waste to their recognition as highly dynamic structures. Current research posits that lysosomes function as a signaling hub that integrates both extracellular and intracellular stimuli, thereby regulating cellular homeostasis. The dysregulation of lysosomal function has been linked to a wide range of diseases. Of note, lysosomes contribute to the activation of mammalian target of rapamycin complex 1 (mTORC1), a key regulator of cellular metabolism. The Ragulator complex, a protein complex anchored on the lysosomal membrane, was initially shown to tether the mTORC1 complex to lysosomes. Recent research has substantially expanded our understanding of the roles of the Ragulator complex in lysosomes, including roles in the regulation of metabolism, inflammation, cell death, cell migration, and the maintenance of homeostasis, via interactions with various proteins. This review summarizes our current knowledge on the diverse functions of the Ragulator complex, highlighting important protein interactions.
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Affiliation(s)
- Kohei Tsujimoto
- Department of Respiratory Medicine and Clinical Immunology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Immunopathology, Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan
| | - Hyota Takamatsu
- Department of Respiratory Medicine and Clinical Immunology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
- Department of Immunopathology, Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan.
| | - Atsushi Kumanogoh
- Department of Respiratory Medicine and Clinical Immunology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Immunopathology, Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan
- Center for Infectious Diseases Education and Research (CiDER), Osaka University, Suita, Osaka, Japan
- Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, Japan
- Japan Agency for Medical Research and Development - Core Research for Evolutional Science and Technology (AMED-CREST), Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS (CAMaD), Osaka University, Osaka, Japan
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3
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Liebscher G, Vujic N, Schreiber R, Heine M, Krebiehl C, Duta-Mare M, Lamberti G, de Smet CH, Hess MW, Eichmann TO, Hölzl S, Scheja L, Heeren J, Kratky D, Huber LA. The lysosomal LAMTOR / Ragulator complex is essential for nutrient homeostasis in brown adipose tissue. Mol Metab 2023; 71:101705. [PMID: 36907508 PMCID: PMC10074977 DOI: 10.1016/j.molmet.2023.101705] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/13/2023] Open
Abstract
OBJECTIVE In brown adipose tissue (iBAT), the balance between lipid/glucose uptake and lipolysis is tightly regulated by insulin signaling. Downstream of the insulin receptor, PDK1 and mTORC2 phosphorylate AKT, which activates glucose uptake and lysosomal mTORC1 signaling. The latter requires the late endosomal/lysosomal adaptor and MAPK and mTOR activator (LAMTOR/Ragulator) complex, which serves to translate the nutrient status of the cell to the respective kinase. However, the role of LAMTOR in metabolically active iBAT has been elusive. METHODS Using an AdipoqCRE-transgenic mouse line, we deleted LAMTOR2 (and thereby the entire LAMTOR complex) in adipose tissue (LT2 AKO). To examine the metabolic consequences, we performed metabolic and biochemical studies in iBAT isolated from mice housed at different temperatures (30 °C, room temperature and 5 °C), after insulin treatment, or in fasted and refed condition. For mechanistic studies, mouse embryonic fibroblasts (MEFs) lacking LAMTOR 2 were analyzed. RESULTS Deletion of the LAMTOR complex in mouse adipocytes resulted in insulin-independent AKT hyperphosphorylation in iBAT, causing increased glucose and fatty acid uptake, which led to massively enlarged lipid droplets. As LAMTOR2 was essential for the upregulation of de novo lipogenesis, LAMTOR2 deficiency triggered exogenous glucose storage as glycogen in iBAT. These effects are cell autonomous, since AKT hyperphosphorylation was abrogated by PI3K inhibition or by deletion of the mTORC2 component Rictor in LAMTOR2-deficient MEFs. CONCLUSIONS We identified a homeostatic circuit for the maintenance of iBAT metabolism that links the LAMTOR-mTORC1 pathway to PI3K-mTORC2-AKT signaling downstream of the insulin receptor.
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Affiliation(s)
- Gudrun Liebscher
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Nemanja Vujic
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstr. 6, 8010 Graz, Austria
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | - Markus Heine
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Caroline Krebiehl
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Madalina Duta-Mare
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstr. 6, 8010 Graz, Austria
| | - Giorgia Lamberti
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Cedric H de Smet
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Michael W Hess
- Institute of Histology and Embryology, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria
| | - Thomas O Eichmann
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | - Sarah Hölzl
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Dagmar Kratky
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstr. 6, 8010 Graz, Austria; BioTechMed-Graz, Mozartgasse 12, 8010 Graz, Austria
| | - Lukas A Huber
- Division of Cell Biology, Biocenter, Medical University Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
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4
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Abstract
Lysosomes are key cellular catabolic centers that also perform fundamental metabolic, signaling and quality control functions. Lysosomes are not static and they respond dynamically to intra‐ and extracellular stimuli triggering changes in organelle numbers, size and position. Such physical changes have a strong impact on lysosomal activity ultimately influencing cellular homeostasis. In this review, we summarize the current knowledge on lysosomal size regulation, on its physiological role(s) and association to several disease conditions.
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Affiliation(s)
- Mariana E G de Araujo
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Gudrun Liebscher
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael W Hess
- Institute of Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Lukas A Huber
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Austrian Drug Screening Institute, ADSI, Innsbruck, Austria
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5
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Yordanov TE, Hipolito VEB, Liebscher G, Vogel GF, Stasyk T, Herrmann C, Geley S, Teis D, Botelho RJ, Hess MW, Huber LA. Biogenesis of lysosome-related organelles complex-1 (BORC) regulates late endosomal/lysosomal size through PIKfyve-dependent phosphatidylinositol-3,5-bisphosphate. Traffic 2019; 20:674-696. [PMID: 31314175 PMCID: PMC6771566 DOI: 10.1111/tra.12679] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 07/15/2019] [Indexed: 01/02/2023]
Abstract
Mechanisms that control lysosomal function are essential for cellular homeostasis. Lysosomes adapt in size and number to cellular needs but little is known about the underlying molecular mechanism. We demonstrate that the late endosomal/lysosomal multimeric BLOC-1-related complex (BORC) regulates the size of these organelles via PIKfyve-dependent phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2 ] production. Deletion of the core BORC component Diaskedin led to increased levels of PI(3,5)P2 , suggesting activation of PIKfyve, and resulted in enhanced lysosomal reformation and subsequent reduction in lysosomal size. This process required AMP-activated protein kinase (AMPK), a known PIKfyve activator, and was additionally dependent on the late endosomal/lysosomal adaptor, mitogen-activated protein kinases and mechanistic target of rapamycin activator (LAMTOR/Ragulator) complex. Consistently, in response to glucose limitation, AMPK activated PIKfyve, which induced lysosomal reformation with increased baseline autophagy and was coupled to a decrease in lysosomal size. These adaptations of the late endosomal/lysosomal system reversed under glucose replete growth conditions. In summary, our results demonstrate that BORC regulates lysosomal reformation and size in response to glucose availability.
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Affiliation(s)
- Teodor E. Yordanov
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Victoria E. B. Hipolito
- Department of Chemistry and Biology and the Graduate Program in Molecular ScienceRyerson UniversityTorontoOntarioCanada
| | - Gudrun Liebscher
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Georg F. Vogel
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
- Department of Pediatrics IMedical University of InnsbruckInnsbruckAustria
| | - Taras Stasyk
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Caroline Herrmann
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Stephan Geley
- Division of Molecular Pathophysiology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - David Teis
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
| | - Roberto J. Botelho
- Department of Chemistry and Biology and the Graduate Program in Molecular ScienceRyerson UniversityTorontoOntarioCanada
| | - Michael W. Hess
- Division of Histology and EmbryologyMedical University of InnsbruckInnsbruckAustria
| | - Lukas A. Huber
- Division of Cell Biology, BiocenterMedical University of InnsbruckInnsbruckAustria
- Austrian Drug Screening Institute, ADSIInnsbruckAustria
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6
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Lamberti G, De Smet CH, Angelova M, Kremser L, Taub N, Herrmann C, Hess MW, Rainer J, Tancevski I, Schweigreiter R, Kofler R, Schmiedinger T, Vietor I, Trajanoski Z, Ejsing CS, Lindner HH, Huber LA, Stasyk T. LAMTOR/Ragulator regulates lipid metabolism in macrophages and foam cell differentiation. FEBS Lett 2019; 594:31-42. [PMID: 31423582 PMCID: PMC7003824 DOI: 10.1002/1873-3468.13579] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 07/30/2019] [Accepted: 07/31/2019] [Indexed: 11/08/2022]
Abstract
Late endosomal/lysosomal adaptor and MAPK and mTOR activator (LAMTOR/Ragulator) is a scaffold protein complex that anchors and regulates multiprotein signaling units on late endosomes/lysosomes. To identify LAMTOR‐modulated endolysosomal proteins, primary macrophages were derived from bone marrow of conditional knockout mice carrying a specific deletion of LAMTOR2 in the monocyte/macrophage cell lineage. Affymetrix‐based transcriptomic analysis and quantitative iTRAQ‐based organelle proteomic analysis of endosomes derived from macrophages were performed. Further analyses showed that LAMTOR could be a novel regulator of foam cell differentiation. The lipid droplet formation phenotype observed in macrophages was additionally confirmed in MEFs, where lipidomic analysis identified cholesterol esters as specifically downregulated in LAMTOR2 knockout cells. The data obtained indicate a function of LAMTOR2 in lipid metabolism.
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Affiliation(s)
- Giorgia Lamberti
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
| | - Cedric H De Smet
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
| | - Mihaela Angelova
- Division of Bioinformatics, Biocenter, Medical University of Innsbruck, Austria
| | - Leopold Kremser
- Division of Clinical Biochemistry, Biocenter, Medical University of Innsbruck, Austria
| | - Nicole Taub
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
| | - Caroline Herrmann
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
| | - Michael W Hess
- Division of Histology and Embryology, Medical University of Innsbruck, Austria
| | - Johannes Rainer
- Division of Molecular Pathophysiology, Biocenter, Medical University of Innsbruck, Austria
| | - Ivan Tancevski
- Department of Internal Medicine, Medical University of Innsbruck, Austria
| | | | - Reinhard Kofler
- Division of Molecular Pathophysiology, Biocenter, Medical University of Innsbruck, Austria
| | - Thomas Schmiedinger
- Department of Therapeutic Radiology and Oncology, Medical University of Innsbruck, Austria
| | - Ilja Vietor
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
| | - Zlatko Trajanoski
- Division of Bioinformatics, Biocenter, Medical University of Innsbruck, Austria
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
| | - Herbert H Lindner
- Division of Clinical Biochemistry, Biocenter, Medical University of Innsbruck, Austria
| | - Lukas A Huber
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria.,Austrian Drug Screening Institute, ADSI, Innsbruck, Austria
| | - Taras Stasyk
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Austria
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7
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Rasheed N, Lima TB, Mercaldi GF, Nascimento AFZ, Silva ALS, Righetto GL, Bar-Peled L, Shen K, Sabatini DM, Gozzo FC, Aparicio R, Smetana JHC. C7orf59/ LAMTOR4 phosphorylation and structural flexibility modulate Ragulator assembly. FEBS Open Bio 2019; 9:1589-1602. [PMID: 31314152 PMCID: PMC6722880 DOI: 10.1002/2211-5463.12700] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/28/2019] [Accepted: 07/15/2019] [Indexed: 01/09/2023] Open
Abstract
Ragulator is a pentamer composed of p18, MP1, p14, C7orf59, and hepatitis B virus X‐interacting protein (HBXIP; LAMTOR 1—5) which acts as a lysosomal scaffold of the Rag GTPases in the amino acid sensitive branch of TORC1 signaling. Here, we present the crystal structure of human HBXIP‐C7orf59 dimer (LAMTOR 4/5) at 2.9 Å and identify a phosphorylation site on C7orf59 which modulates its interaction with p18. Additionally, we demonstrate the requirement of HBXIP‐C7orf59 to stabilize p18 and allow further binding of MP1‐p14. The structure of the dimer revealed an unfolded N terminus in C7orf59 (residues 1–15) which was shown to be essential for p18 binding. Full‐length p18 does not interact stably with MP1‐p14 in the absence of HBXIP‐C7orf59, but deletion of p18 residues 108–161 rescues MP1‐p14 binding. C7orf59 was phosphorylated by protein kinase A (PKA) in vitro and mutation of the conserved Ser67 residue to aspartate prevented phosphorylation and negatively affected the C7orf59 interaction with p18 both in cell culture and in vitro. C7orf59 Ser67 was phosphorylated in human embryonic kidney 293T cells. PKA activation with forskolin induced dissociation of p18 from C7orf59, which was prevented by the PKA inhibitor H‐89. Our results highlight the essential role of HBXIP‐C7orf59 dimer as a nucleator of pentameric Ragulator and support a sequential model of Ragulator assembly in which HBXIP‐C7orf59 binds and stabilizes p18 which allows subsequent binding of MP1‐p14.
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Affiliation(s)
- Nadia Rasheed
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.,Institute of Biology, University of Campinas, Brazil
| | - Tatiani B Lima
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.,Institute of Chemistry, University of Campinas, Brazil
| | - Gustavo F Mercaldi
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Andrey F Z Nascimento
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Ana L S Silva
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Germanna L Righetto
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
| | - Liron Bar-Peled
- The Massachusetts General Hospital Cancer Center, Boston, MA, USA
| | - Kuang Shen
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Howard Hughes Medical Institute, Cambridge, MA, USA.,Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA, USA
| | - David M Sabatini
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Whitehead Institute for Biomedical Research, Cambridge, MA, USA.,Howard Hughes Medical Institute, Cambridge, MA, USA.,Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Fabio C Gozzo
- Institute of Chemistry, University of Campinas, Brazil
| | | | - Juliana H C Smetana
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil
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8
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Chichger H, Braza J, Duong H, Stark M, Harrington EO. Neovascularization in the pulmonary endothelium is regulated by the endosome: Rab4-mediated trafficking and p18-dependent signaling. Am J Physiol Lung Cell Mol Physiol 2015; 309:L700-9. [PMID: 26254426 DOI: 10.1152/ajplung.00235.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 08/04/2015] [Indexed: 11/22/2022] Open
Abstract
Neovascularization, the formation of new blood vessels, requires multiple processes including vascular leak, migration, and adhesion. Endosomal proteins, such as Rabs, regulate trafficking of key signaling proteins involved in neovascularization. The novel endosome protein, p18, enhances vascular endothelial (VE)-cadherin recycling from early endosome to cell junction to improve pulmonary endothelial barrier function. Since endothelial barrier integrity is vital in neovascularization, we sought to elucidate the role for endosome proteins p18 and Rab4, Rab7, and Rab9 in the process of vessel formation within the pulmonary vasculature. Overexpression of wild-type p18 (p18(wt)), but not the nonendosomal-binding mutant (p18(N39)), significantly increased lung microvascular endothelial cell migration, adhesion, and both in vitro and in vivo tube formation. Chemical inhibition of mTOR or p38 attenuated the proneovascularization role of p18(wt). Similar to the effect of p18(wt), overexpression of prorecycling wild-type (Rab4(WT)) and endosome-anchored (Rab4(Q67L)) Rab4 enhanced neovascularization processes, whereas molecular inhibition of Rab4, by using the nonendosomal-binding mutant (Rab4(S22N)) attenuated VEGF-induced neovascularization. Unlike p18, Rab4-induced neovascularization was independent of mTOR or p38 inhibition but was dependent on p18 expression. This study shows for the first time that neovascularization within the pulmonary vasculature is dependent on the prorecycling endocytic proteins Rab4 and p18.
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Affiliation(s)
- Havovi Chichger
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, and Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
| | - Julie Braza
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, and Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
| | - Huetran Duong
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, and Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
| | - Myranda Stark
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, and Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
| | - Elizabeth O Harrington
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, and Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island
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