期刊
JOURNAL OF EXPERIMENTAL MEDICINE
卷 198, 期 4, 页码 603-614出版社
ROCKEFELLER UNIV PRESS
DOI: 10.1084/jem.20021363
关键词
integrin; Rac1; Arf6; PIP5K; Yersinia uptake
资金
- NIAID NIH HHS [R37 AI023538, R37 AI23538] Funding Source: Medline
- NIDDK NIH HHS [P30DK34928, P30 DK034928] Funding Source: Medline
Efficient entry of the bacterium Yersinia pseudotuberculosis into mammalian cells requires the binding of the bacterial invasin protein to beta1 integrin receptors and the activation of the small GTPase Rac1. We report here that this Rac1-dependent pathway involves recruitment of phosphoinositol-4-phosphate-5-kinase (PIP5K) to form phosphoinositol-4,5-bisphosphate (PIP2) at the phagocytic cup. Reducing the concentration of PIP2 in the target cell by using a membrane-targeted PIP2-specific phosphatase lowered bacterial uptake proportionately. PIP2 formation is regulated by Arf6. An Arf6 derivative defective for nucleotide binding (Arf6N122I) interfered with uptake and decreased the level of PIP2 around extracellular bacteria bound to host cells. This reduction in PIP2, occurred in spite of fact that PIP5K appeared to be recruited efficiently to the site of bacterial binding, indicating a role for Arf6 in activation of the kinase. The elimination of the Rac1-GTP-bound form from the cell by the introduction of the Y. pseudotuberculosis YopE RhoGAP protein could be bypassed by the overproduction of either PIP5K or Arf6, although the degree of bypass was greater for Arf6 transfectants. These results indicate that both Arf6 and PIP5K are involved in integrin-dependent uptake, and that Arf6 participates in both activation of PIP5K as well as in other events associated with bacterial uptake.
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