Efficient uptake of Yersinia pseudotuberculosis via integrin receptors involves a Rac1-Arp 2/3 pathway that bypasses N-WASP function.
Efficient uptake of Yersinia pseudotuberculosis into cultured mammalian cells is the result of high-affinity binding of invasin to beta1 chain integrins. We demonstrate here that uptake requires Rac1 and Arp 2/3 function. Bacterial uptake was stimulated by GTPgammaS, but was inhibited in mammalian cells transfected with the interfering Rac1-N17 derivative. Rac1 was found to be activated in response to integrin engagement by invasin, whereas Rac1 and Arp 2/3 were found to be intensely localized around phagosomes bearing bacteria, indicating a specific role for Rac1 signalling from the nascent phagosome to downstream effectors. To determine whether the Arp 2/3 complex was a component of this proposed pathway, cells overproducing various derivatives of Scar1/WAVE1, an Arp 2/3-binding protein, were analysed. Sequestration of Arp 2/3 away from the phagocytic cup as a result of Scar1/WAVE1 overproduction dramatically inhibited uptake. To determine whether signalling from Rac1 to Arp 2/3 occurred via N-WASP, uptake was analysed in a cell line lacking expression of WASP and N-WASP. Uptake was unaffected by the absence of these proteins, indicating that beta1 integrin signalling from Rac1 to Arp 2/3 can occur in the absence of N-WASP function.
Alrutz
M A
MA
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue M and V 409, Boston, MA 02111, USA.
Srivastava
A
A
Wong
K W
KW
D'Souza-Schorey
C
C
Tang
M
M
Ch'Ng
L E
LE
Snapper
S B
SB
Isberg
R R
RR
D016475:3T3 Cells; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism; D018829:Adhesins, Bacterial; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D019556:COS Cells; D002460:Cell Line; D002463:Cell Membrane Permeability; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins; D004338:Drug Combinations; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009821:Oils; D010588:Phagosomes / Q000382:microbiology; D010636:Phenols; D011956:Receptors, Cell Surface / Q000378:metabolism*; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D015011:Yersinia pseudotuberculosis / Q000472:pathogenicity*; D015012:Yersinia pseudotuberculosis Infections / Q000382:microbiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
C495926:ACTR2 protein, human; C495928:ACTR3 protein, human; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; C495927:Actr2 protein, mouse; C495929:Actr3 protein, mouse; D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; D004338:Drug Combinations; D019012:Integrin beta1; D009419:Nerve Tissue Proteins; D009821:Oils; C027222:P & S Liquid; D010636:Phenols; D011956:Receptors, Cell Surface; C495771:WASL protein, human; C495772:Wasl protein, mouse; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C053476:invasin, Yersinia; D020830:rac1 GTP-Binding Protein