Trafficking of the microdomain scaffolding protein reggie-1/flotillin-2

Eur J Cell Biol. 2008 Apr;87(4):211-26. doi: 10.1016/j.ejcb.2007.12.001. Epub 2008 Jan 30.

Abstract

The reggie/flotillin proteins oligomerize and associate into clusters which form scaffolds for membrane microdomains. Besides their localization at the plasma membrane, the reggies/flotillins reside at various intracellular compartments; however, the trafficking pathways used by reggie-1/flotillin-2 remain unclear. Here, we show that trafficking of reggie-1/flotillin-2 is BFA sensitive and that deletion mutants of reggie-1/flotillin-2 accumulate in the Golgi complex in HeLa, Jurkat and PC12 cells, suggesting Golgi-dependent trafficking of reggie-1/flotillin-2. Using total internal reflection fluorescence microscopy, we observed fast cycling of reggie-1/flotillin-2-positive vesicles at the plasma membrane, which engaged in transient interactions with the plasma membrane only. Reggie-1/flotillin-2 cycling was independent of clathrin, but was inhibited by cholesterol depletion and microtubule disruption. Cycling of reggie-1/flotillin-2 was negatively correlated with cell-cell contact formation but was stimulated by serum, epidermal growth factor and by cholesterol loading mediated by low density lipoproteins. However, reggie-1/flotillin-2 was neither involved in endocytosis of the epidermal growth factor itself nor in endocytosis of GPI-GFPs or the GPI-anchored cellular prion protein (PrP(c)). Reggie-2/flotillin-1 and stomatin-1 also exhibited cycling at the plasma membrane similar to reggie-1/flotillin-2, but these vesicles and microdomains only partially co-localized with reggie-2/flotillin-1. Thus, regulated vesicular cycling might be a general feature of SPFH protein-dependent trafficking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cholesterol / metabolism
  • Endocytosis
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / ultrastructure
  • HeLa Cells
  • Humans
  • Jurkat Cells
  • Membrane Microdomains / chemistry
  • Membrane Microdomains / metabolism*
  • Membrane Microdomains / ultrastructure
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Microtubules / metabolism
  • Mutation
  • Nerve Tissue Proteins
  • PC12 Cells
  • Prions / metabolism
  • Protein Structure, Tertiary
  • Protein Transport
  • Rats

Substances

  • Membrane Proteins
  • Nerve Tissue Proteins
  • Prions
  • STOML1 protein, human
  • flotillins
  • Cholesterol