Clathrin- and caveolin-1-independent endocytosis: entry of simian virus 40 into cells devoid of caveolae.
Simian Virus 40 (SV40) has been shown to enter host cells by caveolar endocytosis followed by transport via caveosomes to the endoplasmic reticulum (ER). Using a caveolin-1 (cav-1)-deficient cell line (human hepatoma 7) and embryonic fibroblasts from a cav-1 knockout mouse, we found that in the absence of caveolae, but also in wild-type embryonic fibroblasts, the virus exploits an alternative, cav-1-independent pathway. Internalization was rapid (t1/2 = 20 min) and cholesterol and tyrosine kinase dependent but independent of clathrin, dynamin II, and ARF6. The viruses were internalized in small, tight-fitting vesicles and transported to membrane-bounded, pH-neutral organelles similar to caveosomes but devoid of cav-1 and -2. The viruses were next transferred by microtubule-dependent vesicular transport to the ER, a step that was required for infectivity. Our results revealed the existence of a virus-activated endocytic pathway from the plasma membrane to the ER that involves neither clathrin nor caveolae and that can be activated also in the presence of cav-1.
Damm
Eva-Maria
EM
Institute of Biochemistry, Swiss Federal Institute of Technology Zürich (ETHZ), CH-8093 Zürich, Switzerland.
Pelkmans
Lucas
L
Kartenbeck
Jürgen
J
Mezzacasa
Anna
A
Kurzchalia
Teymuras
T
Helenius
Ari
A
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000502:physiology; D008841:Actin Cytoskeleton / Q000187:drug effects / Q000502:physiology; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D020126:Brefeldin A / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000235:genetics; D021941:Caveolae / Q000502:physiology*; D051242:Caveolin 1; D051243:Caveolin 2; D022461:Caveolins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000172:deficiency / Q000502:physiology; D002966:Clathrin / Q000502:physiology*; D003902:Detergents / Q000737:chemistry; D034285:Dynamin II / Q000235:genetics / Q000502:physiology; D004622:Embryo, Mammalian / Q000166:cytology; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D018871:Endoplasmic Reticulum, Smooth / Q000737:chemistry / Q000502:physiology; D005347:Fibroblasts / Q000187:drug effects / Q000648:ultrastructure / Q000821:virology; D015870:Gene Expression; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D021962:Membrane Microdomains / Q000737:chemistry / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D015739:Nocodazole / Q000494:pharmacology; D010750:Phosphoproteins / Q000235:genetics; D012672:Semliki forest virus / Q000502:physiology; D013539:Simian virus 40 / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D014168:Transferrin / Q000378:metabolism; D022161:Transport Vesicles / Q000502:physiology / Q000648:ultrastructure; D014404:Tubulin / Q000235:genetics; D033921:Vesicular Transport Proteins
D000089982:ADP-Ribosylation Factor 6; D048868:Adaptor Proteins, Signal Transducing; D000957:Antigens, Viral, Tumor; D019086:Bridged Bicyclo Compounds, Heterocyclic; C495540:CAV1 protein, human; D002135:Calcium-Binding Proteins; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D051243:Caveolin 2; D022461:Caveolins; D002966:Clathrin; D003902:Detergents; C082729:Eps15 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D013844:Thiazoles; D053778:Thiazolidines; D014168:Transferrin; D014404:Tubulin; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; D020126:Brefeldin A; D002784:Cholesterol; D019833:Genistein; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; C000715727:Arf6 protein, mouse; D034285:Dynamin II; D015739:Nocodazole; C037067:latrunculin A