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Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells

The iron-binding protein lactoferrin and the cell-penetrating peptides derived from its sequence utilise endocytosis to enter different cell types. The full-length protein has been extensively investigated as a potential therapeutic against a range of pathogenic bacteria, fungi, and viruses, includi...

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Autores principales: Sayers, Edward John, Palmer, Iwan, Hope, Lucy, Hope, Paul, Watson, Peter, Jones, Arwyn Tomos
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9032238/
https://www.ncbi.nlm.nih.gov/pubmed/35456688
http://dx.doi.org/10.3390/pharmaceutics14040855
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author Sayers, Edward John
Palmer, Iwan
Hope, Lucy
Hope, Paul
Watson, Peter
Jones, Arwyn Tomos
author_facet Sayers, Edward John
Palmer, Iwan
Hope, Lucy
Hope, Paul
Watson, Peter
Jones, Arwyn Tomos
author_sort Sayers, Edward John
collection PubMed
description The iron-binding protein lactoferrin and the cell-penetrating peptides derived from its sequence utilise endocytosis to enter different cell types. The full-length protein has been extensively investigated as a potential therapeutic against a range of pathogenic bacteria, fungi, and viruses, including SARS-CoV-2. As a respiratory antiviral agent, several activity mechanisms have been demonstrated for lactoferrin, at the extracellular and plasma membrane levels, but as a protein that enters cells it may also have intracellular antiviral activity. Characterisation of lactoferrin’s binding, endocytic traffic to lysosomes, or recycling endosomes for exocytosis is lacking, especially in lung cell models. Here, we use confocal microscopy, flow cytometry, and degradation assays to evaluate binding, internalisation, endocytic trafficking, and the intracellular fate of bovine lactoferrin in human lung A549 cells. In comparative studies with endocytic probes transferrin and dextran, we show that lactoferrin binds to negative charges on the cell surface and actively enters cells via fluid-phase endocytosis, in a receptor-independent manner. Once inside the cell, we show that it is trafficked to lysosomes where it undergoes degradation within two hours. These findings provide opportunities for investigating both lactoferrin and derived cell-penetrating peptides activities of targeting intracellular pathogens.
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spelling pubmed-90322382022-04-23 Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells Sayers, Edward John Palmer, Iwan Hope, Lucy Hope, Paul Watson, Peter Jones, Arwyn Tomos Pharmaceutics Article The iron-binding protein lactoferrin and the cell-penetrating peptides derived from its sequence utilise endocytosis to enter different cell types. The full-length protein has been extensively investigated as a potential therapeutic against a range of pathogenic bacteria, fungi, and viruses, including SARS-CoV-2. As a respiratory antiviral agent, several activity mechanisms have been demonstrated for lactoferrin, at the extracellular and plasma membrane levels, but as a protein that enters cells it may also have intracellular antiviral activity. Characterisation of lactoferrin’s binding, endocytic traffic to lysosomes, or recycling endosomes for exocytosis is lacking, especially in lung cell models. Here, we use confocal microscopy, flow cytometry, and degradation assays to evaluate binding, internalisation, endocytic trafficking, and the intracellular fate of bovine lactoferrin in human lung A549 cells. In comparative studies with endocytic probes transferrin and dextran, we show that lactoferrin binds to negative charges on the cell surface and actively enters cells via fluid-phase endocytosis, in a receptor-independent manner. Once inside the cell, we show that it is trafficked to lysosomes where it undergoes degradation within two hours. These findings provide opportunities for investigating both lactoferrin and derived cell-penetrating peptides activities of targeting intracellular pathogens. MDPI 2022-04-13 /pmc/articles/PMC9032238/ /pubmed/35456688 http://dx.doi.org/10.3390/pharmaceutics14040855 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sayers, Edward John
Palmer, Iwan
Hope, Lucy
Hope, Paul
Watson, Peter
Jones, Arwyn Tomos
Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title_full Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title_fullStr Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title_full_unstemmed Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title_short Fluid-Phase Endocytosis and Lysosomal Degradation of Bovine Lactoferrin in Lung Cells
title_sort fluid-phase endocytosis and lysosomal degradation of bovine lactoferrin in lung cells
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9032238/
https://www.ncbi.nlm.nih.gov/pubmed/35456688
http://dx.doi.org/10.3390/pharmaceutics14040855
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