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Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion

Macropinocytosis, the internalization of extracellular fluid and material by plasma membrane ruffles, is critical for antigen presentation, cell metabolism, and signaling. Macropinosomes mature through homotypic and heterotypic fusion with endosomes and ultimately merge with lysosomes. The molecular...

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Detalles Bibliográficos
Autores principales: Dolat, Lee, Spiliotis, Elias T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004444/
https://www.ncbi.nlm.nih.gov/pubmed/27551056
http://dx.doi.org/10.1083/jcb.201603030
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author Dolat, Lee
Spiliotis, Elias T.
author_facet Dolat, Lee
Spiliotis, Elias T.
author_sort Dolat, Lee
collection PubMed
description Macropinocytosis, the internalization of extracellular fluid and material by plasma membrane ruffles, is critical for antigen presentation, cell metabolism, and signaling. Macropinosomes mature through homotypic and heterotypic fusion with endosomes and ultimately merge with lysosomes. The molecular underpinnings of this clathrin-independent endocytic pathway are largely unknown. Here, we show that the filamentous septin GTPases associate preferentially with maturing macropinosomes in a phosphatidylinositol 3,5-bisphosphate–dependent manner and localize to their contact/fusion sites with macropinosomes/endosomes. Septin knockdown results in large clusters of docked macropinosomes, which persist longer and exhibit fewer fusion events. Septin depletion and overexpression down-regulates and enhances, respectively, the delivery of fluid-phase cargo to lysosomes, without affecting Rab5 and Rab7 recruitment to macropinosomes/endosomes. In vitro reconstitution assays show that fusion of macropinosomes/endosomes is abrogated by septin immunodepletion and function-blocking antibodies and is induced by recombinant septins in the absence of cytosol and polymerized actin. Thus, septins regulate fluid-phase cargo traffic to lysosomes by promoting macropinosome maturation and fusion with endosomes/lysosomes.
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spelling pubmed-50044442017-02-28 Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion Dolat, Lee Spiliotis, Elias T. J Cell Biol Research Articles Macropinocytosis, the internalization of extracellular fluid and material by plasma membrane ruffles, is critical for antigen presentation, cell metabolism, and signaling. Macropinosomes mature through homotypic and heterotypic fusion with endosomes and ultimately merge with lysosomes. The molecular underpinnings of this clathrin-independent endocytic pathway are largely unknown. Here, we show that the filamentous septin GTPases associate preferentially with maturing macropinosomes in a phosphatidylinositol 3,5-bisphosphate–dependent manner and localize to their contact/fusion sites with macropinosomes/endosomes. Septin knockdown results in large clusters of docked macropinosomes, which persist longer and exhibit fewer fusion events. Septin depletion and overexpression down-regulates and enhances, respectively, the delivery of fluid-phase cargo to lysosomes, without affecting Rab5 and Rab7 recruitment to macropinosomes/endosomes. In vitro reconstitution assays show that fusion of macropinosomes/endosomes is abrogated by septin immunodepletion and function-blocking antibodies and is induced by recombinant septins in the absence of cytosol and polymerized actin. Thus, septins regulate fluid-phase cargo traffic to lysosomes by promoting macropinosome maturation and fusion with endosomes/lysosomes. The Rockefeller University Press 2016-08-29 /pmc/articles/PMC5004444/ /pubmed/27551056 http://dx.doi.org/10.1083/jcb.201603030 Text en © 2016 Dolat and Spiliotis This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Research Articles
Dolat, Lee
Spiliotis, Elias T.
Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title_full Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title_fullStr Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title_full_unstemmed Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title_short Septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
title_sort septins promote macropinosome maturation and traffic to the lysosome by facilitating membrane fusion
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004444/
https://www.ncbi.nlm.nih.gov/pubmed/27551056
http://dx.doi.org/10.1083/jcb.201603030
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