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Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells

The kidney proximal tubule (PT) elaborates a uniquely high-capacity apical endocytic pathway to retrieve albumin and other proteins that escape the glomerular filtration barrier. Megalin and cubilin/amnionless (CUBAM) receptors engage Dab2 in these cells to mediate clathrin-dependent uptake of filte...

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Autores principales: Rbaibi, Youssef, Long, Kimberly R., Shipman, Katherine E., Ren, Qidong, Baty, Catherine J., Kashlan, Ossama B., Weisz, Ora A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10295476/
https://www.ncbi.nlm.nih.gov/pubmed/37126375
http://dx.doi.org/10.1091/mbc.E22-11-0510
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author Rbaibi, Youssef
Long, Kimberly R.
Shipman, Katherine E.
Ren, Qidong
Baty, Catherine J.
Kashlan, Ossama B.
Weisz, Ora A.
author_facet Rbaibi, Youssef
Long, Kimberly R.
Shipman, Katherine E.
Ren, Qidong
Baty, Catherine J.
Kashlan, Ossama B.
Weisz, Ora A.
author_sort Rbaibi, Youssef
collection PubMed
description The kidney proximal tubule (PT) elaborates a uniquely high-capacity apical endocytic pathway to retrieve albumin and other proteins that escape the glomerular filtration barrier. Megalin and cubilin/amnionless (CUBAM) receptors engage Dab2 in these cells to mediate clathrin-dependent uptake of filtered ligands. Knockout of megalin or Dab2 profoundly inhibits apical endocytosis and is believed to atrophy the endocytic pathway. We generated CRISPR/Cas9 knockout (KO) clones lacking cubilin, megalin, or Dab2 expression in highly differentiated PT cells and determined the impact on albumin internalization and endocytic pathway function. KO of each component had different effects on the concentration dependence of albumin uptake as well its distribution within PT cells. Reduced uptake of a fluid phase marker was also observed, with megalin KO cells having the most dramatic decline. Surprisingly, protein levels and distribution of key endocytic proteins were preserved in KO PT cell lines and in megalin KO mice, despite the reduced endocytic activity. Our data highlight specific functions of megalin, cubilin, and Dab2 in apical endocytosis and demonstrate that these proteins drive endocytic flux without compromising the physical integrity of the apical endocytic pathway. Our studies suggest a novel model to explain how these components coordinate endocytic uptake in PT cells.
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spelling pubmed-102954762023-08-16 Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells Rbaibi, Youssef Long, Kimberly R. Shipman, Katherine E. Ren, Qidong Baty, Catherine J. Kashlan, Ossama B. Weisz, Ora A. Mol Biol Cell Articles The kidney proximal tubule (PT) elaborates a uniquely high-capacity apical endocytic pathway to retrieve albumin and other proteins that escape the glomerular filtration barrier. Megalin and cubilin/amnionless (CUBAM) receptors engage Dab2 in these cells to mediate clathrin-dependent uptake of filtered ligands. Knockout of megalin or Dab2 profoundly inhibits apical endocytosis and is believed to atrophy the endocytic pathway. We generated CRISPR/Cas9 knockout (KO) clones lacking cubilin, megalin, or Dab2 expression in highly differentiated PT cells and determined the impact on albumin internalization and endocytic pathway function. KO of each component had different effects on the concentration dependence of albumin uptake as well its distribution within PT cells. Reduced uptake of a fluid phase marker was also observed, with megalin KO cells having the most dramatic decline. Surprisingly, protein levels and distribution of key endocytic proteins were preserved in KO PT cell lines and in megalin KO mice, despite the reduced endocytic activity. Our data highlight specific functions of megalin, cubilin, and Dab2 in apical endocytosis and demonstrate that these proteins drive endocytic flux without compromising the physical integrity of the apical endocytic pathway. Our studies suggest a novel model to explain how these components coordinate endocytic uptake in PT cells. The American Society for Cell Biology 2023-06-01 /pmc/articles/PMC10295476/ /pubmed/37126375 http://dx.doi.org/10.1091/mbc.E22-11-0510 Text en © 2023 Rbaibi et al. “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology. https://creativecommons.org/licenses/by-nc-sa/4.0/This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 4.0 Unported Creative Commons License.
spellingShingle Articles
Rbaibi, Youssef
Long, Kimberly R.
Shipman, Katherine E.
Ren, Qidong
Baty, Catherine J.
Kashlan, Ossama B.
Weisz, Ora A.
Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title_full Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title_fullStr Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title_full_unstemmed Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title_short Megalin, cubilin, and Dab2 drive endocytic flux in kidney proximal tubule cells
title_sort megalin, cubilin, and dab2 drive endocytic flux in kidney proximal tubule cells
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10295476/
https://www.ncbi.nlm.nih.gov/pubmed/37126375
http://dx.doi.org/10.1091/mbc.E22-11-0510
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