Article abstract
Nature Cell Biology 3, 473 - 483 (2001)
Published online: 18 April 2001 | doi:10.1038/35074539
Caveolar endocytosis of simian virus 40 reveals a new two-step vesicular-transport pathway to the ER
Lucas Pelkmans1, Jürgen Kartenbeck2 & Ari Helenius1
Abstract
Simian virus 40 (SV40) is unusual among animal viruses in that it enters cells through caveolae, and the internalized virus accumulates in a smooth endoplasmic reticulum (ER) compartment. Using video-enhanced, dual-colour, live fluorescence microscopy, we show the uptake of individual virus particles in CV-1 cells. After associating with caveolae, SV40 leaves the plasma membrane in small, caveolin-1-containing vesicles. It then enters larger, peripheral organelles with a non-acidic pH. Although rich in caveolin-1, these organelles do not contain markers for endosomes, lysosomes, ER or Golgi, nor do they acquire ligands of clathrin-coated vesicle endocytosis. After several hours in these organelles, SV40 is sorted into tubular, caveolin-free membrane vesicles that move rapidly along microtubules, and is deposited in perinuclear, syntaxin 17-positive, smooth ER organelles. The microtubule-disrupting agent nocodazole inhibits formation and transport of these tubular carriers, and blocks viral infection. Our results demonstrate the existence of a two-step transport pathway from plasma-membrane caveolae, through an intermediate organelle (termed the caveosome), to the ER. This pathway bypasses endosomes and the Golgi complex, and is part of the productive infectious route used by SV40.
- Institute of Biochemistry, Swiss Federal Institute of Technology, Universitaetstrasse 16, CH-8092 Zürich, Switzerland
- German Cancer Research Center (DKFZ) Heidelberg, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
Correspondence to: Ari Helenius1 e-mail: ari.helenius@bc.biol.ethz.ch
