Receptor-mediated internalization promotes increased endosome size and number in a RAB4- and RAB5-dependent manner

Eur J Cell Biol. 2023 Sep;102(3):151339. doi: 10.1016/j.ejcb.2023.151339. Epub 2023 Jul 6.

Abstract

Despite their significance in receptor-mediated internalization and continued signal transduction in cells, early/sorting endosomes (EE/SE) remain incompletely characterized, with many outstanding questions that surround the dynamics of their size and number. While several studies have reported increases in EE/SE size and number resulting from endocytic events, few studies have addressed such dynamics in a methodological and quantitative manner. Herein we apply quantitative fluorescence microscopy to measure the size and number of EE/SE upon internalization of two different ligands: transferrin and epidermal growth factor. Additionally, we used siRNA knock-down to determine the involvement of 5 different endosomal RAB proteins (RAB4, RAB5, RAB8A, RAB10 and RAB11A) in EE/SE dynamics. Our study provides new information on the dynamics of endosomes during endocytosis, an important reference for researchers studying receptor-mediated internalization and endocytic events.

Keywords: Endosome number; Endosome size; Internalization; RAB10; RAB11A; RAB4; RAB5; RAB8A.

MeSH terms

  • Cell Line, Tumor
  • Endocytosis / physiology
  • Endosomes / metabolism
  • Humans
  • Protein Transport / physiology
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism
  • rab4 GTP-Binding Proteins* / genetics
  • rab4 GTP-Binding Proteins* / metabolism
  • rab5 GTP-Binding Proteins* / genetics
  • rab5 GTP-Binding Proteins* / metabolism

Substances

  • rab GTP-Binding Proteins
  • rab4 GTP-Binding Proteins
  • rab5 GTP-Binding Proteins