We show that cells lacking two Dictyostelium class I phosphatidylinositol (PI) 3′ kinases (PI3K and pi3k1/2-null cells) or wild-type cells treated with the PI3K inhibitor LY294002 are unable to properly polarize, are very defective in the temporal, spatial, and quantitative regulation of chemoattractant-mediated filamentous (F)-actin polymerization, and chemotax very slowly. PI3K is thought to produce membrane lipid-binding sites for localization of PH domain–containing proteins. We demonstrate that in response to chemoattractants three PH domain–containing proteins do not localize to the leading edge in pi3k1/2-null cells, and the translocation is blocked in wild-type cells by LY294002. Cells lacking one of these proteins, phdA-null cells, exhibit defects in the level and kinetics of actin polymerization at the leading edge and have chemotaxis phenotypes that are distinct from those described previously for protein kinase B (PKB) (pkbA)-null cells. Phenotypes of PhdA-dominant interfering mutations suggest that PhdA is an adaptor protein that regulates F-actin localization in response to chemoattractants and links PI3K to the control of F-actin polymerization at the leading edge during pseudopod formation. We suggest that PKB and PhdA lie downstream from PI3K and control different downstream effector pathways that are essential for proper chemotaxis.
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14 May 2001
Article|
May 14 2001
Role of Phosphatidylinositol 3′ Kinase and a Downstream Pleckstrin Homology Domain–Containing Protein in Controlling Chemotaxis inDictyostelium
Satoru Funamoto,
Satoru Funamoto
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
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Kristina Milan,
Kristina Milan
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
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Ruedi Meili,
Ruedi Meili
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
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Richard A. Firtel
Richard A. Firtel
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
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Satoru Funamoto
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
Kristina Milan
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
Ruedi Meili
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
Richard A. Firtel
aSection of Cell and Developmental Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla, California 92093
Abbreviations used in this paper: CRAC, Ca2+ release-activated Ca2+; GFP, green fluorescent protein; PH, pleckstrin homology; PhdA, PH domain–containing protein A; PI, phosphatidylinositol; PI3K, PI 3′-kinase; PI (3,4,5)P3, PI 3,4,5-triphosphate; PI (3,4)P2, PI 3,4-bisphosphate; PKB, protein kinase B.
Received:
November 29 2000
Revision Requested:
March 20 2001
Accepted:
March 29 2001
Online ISSN: 1540-8140
Print ISSN: 0021-9525
© 2001 The Rockefeller University Press
2001
The Rockefeller University Press
J Cell Biol (2001) 153 (4): 795–810.
Article history
Received:
November 29 2000
Revision Requested:
March 20 2001
Accepted:
March 29 2001
Citation
Satoru Funamoto, Kristina Milan, Ruedi Meili, Richard A. Firtel; Role of Phosphatidylinositol 3′ Kinase and a Downstream Pleckstrin Homology Domain–Containing Protein in Controlling Chemotaxis inDictyostelium. J Cell Biol 14 May 2001; 153 (4): 795–810. doi: https://doi.org/10.1083/jcb.153.4.795
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