Inactivation of Two Dictyostelium discoideum Genes, DdPIK1 and DdPIK2, Encoding Proteins Related to Mammalian Phosphatidylinositide 3-kinases, Results in Defects in Endocytosis, Lysosome to Postlysosome Transport, and Actin Cytoskeleton Organization

Buczynski, Greg; Grove, Bryon; Nomura, Anson M.; Kleve, Maurice G.; Bush, John; Firtel, Richard A.; Cardelli, James A.

doi:10.1083/jcb.136.6.1271

Cited by 98 publications

(82 citation statements)

References 71 publications

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“…It is possible that the translocation is too transient to be visualized. Alternatively, in shk1 null cells, the phagocytosis defect may be an indirect effect of alterations in the actin cytoskeleton and its reorganization in shk1 null cells and may not be directly regulated by PI3K (Buczynski et al 1997).…”

Section: Phagocytosis Is Abnormal In Shk1 Null Cellsmentioning

confidence: 99%

An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway

Moniakis

Funamoto²,

Fukuzawa³

et al. 2001

Genes Dev.

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SHK1 is a novel dual-specificity kinase that contains an SH2 domain in its C-terminal region. We demonstrate that SHK1 is required for proper chemotaxis and phagocytosis. Mutant shk1 null cells lack polarity, move very slowly, and exhibit an elevated and temporally extended chemoattractant-mediated activation of the kinase Akt/PKB. GFP fusions of the PH domain of Akt/PKB or the PH-domain-containing protein CRAC, which become transiently associated with the plasma membrane after a global stimulation with a chemoattractant, remain associated with the plasma membrane for an extended period of time in shk1 null cells. These results suggest that SHK1 is a negative regulator of the PI3K (phosphatidylinositol-3 kinase) pathway. Furthermore, when a chemoattractant gradient is applied to a wild-type cell, these PH-domaincontaining proteins and the F-actin-binding protein coronin localize to its leading edge, but in an shk1 null cell they become randomly associated with the plasma membrane and cortex, irrespective of the direction of the chemoattractant gradient, suggesting that SHK1 is required for the proper spatiotemporal control of F-actin levels in chemotaxing cells. Consistent with such functions, SHK1 is localized at the plasma membrane/ cortex, and we show that its SH2 domain is required for this localization and the proper function of SHK1.

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Section: Phagocytosis Is Abnormal In Shk1 Null Cellsmentioning

confidence: 99%

An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway

Moniakis

Funamoto²,

Fukuzawa³

et al. 2001

Genes Dev.

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“…Null mutants lacking both DdPIK1 and DdPIK2 are severely deficient in chemotaxis and macropinosome formation, two processes involving plasma-membrane-driven actin polymerization. These phenotypes can be reproduced by treating wild-type cells with 0.2 µM wortmannin or 20 µM LY294002 (Buczynski et al, 1997;Rupper et al, 2001;Zhou et al, 1995). We therefore used these drugs to test the implication of PI3K activity in SFICM.…”

Section: Journal Of Cell Science 116 (21)mentioning

confidence: 99%

Shear flow-induced motility ofDictyostelium discoideumcells on solid substrate

Décavé

Rieu

Dalous

et al. 2003

Journal of Cell Science

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Application of a mild hydrodynamic shear stress to Dicytostelium discoideum cells, unable to detach cells passively from the substrate, triggers a cellular response consisting of steady membrane peeling at the rear edge of the cell and periodic cell contact extensions at its front edge. Both processes require an active actin cytoskeleton. The cell movement induced by the hydrodynamic forces is very similar to amoeboid cell motion during chemotaxis, as for its kinematic parameters and for the involvement of phosphatidylinositol(3,4,5)-trisphosphate internal gradient to maintain cell polarity. Inhibition of phosphoinositide 3-kinases by LY294002 randomizes the orientation of cell movement with respect to the flow without modifying cell speed. Two independent signaling pathways are, therefore, induced in D. discoideum in response to external forces. The first increases the frequency of pseudopodium extension, whereas the second redirects the actin cytoskeleton polymerization machinery to the edge opposite to the stressed side of the cell. Movies available online

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“…Pi3k1/2-null cells are affected with respect to pinocytosis (19), suggesting a role for PI(3,4,5)P 3 in this process. The inhibitors of phospholipase C, an enzyme converting PI(4,5)P 2 into Ins(1,4,5)P 3 and diacylglycerol, reduce the rate of phagocytosis (20,21).…”

mentioning

confidence: 99%

A Diverse Family of Inositol 5-Phosphatases Playing a Role in Growth and Development in Dictyostelium discoideum

Loovers

Veenstra

Snippe

et al. 2003

Journal of Biological Chemistry

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Inositol phosphate-containing molecules play an important role in a broad range of cellular processes. Inositol 5-phosphatases participate in the regulation of these signaling molecules. We have identified four inositol 5-phosphatases in Dictyostelium discoideum, Dd5P1-4, showing a high diversity in domain composition. Dd5P1 possesses only a inositol 5-phosphatase catalytic domain. An unique domain composition is present in Dd5P2 containing a RCC1-like domain. RCC1 has a seven-bladed propeller structure and interacts with Gproteins. Dd5P3 and Dd5P4 have a domain composition similar to human Synaptojanin with a SacI domain and OCRL with a RhoGAP domain, respectively. We have expressed the catalytic domains and show that these inositol 5-phosphatases have different substrate preferences. Single and double gene inactivation suggest a functional redundancy for Dd5P1, Dd5P2, and Dd5P3. Inactivation of the gene coding for Dd5P4 leads to defects in growth and development. These defects are restored by the expression of the complete protein but not by the 5-phosphatase catalytic domain.Inositol phosphates play a role in a variety of eukaryotic cellular processes, including chemotaxis and membrane trafficking. They are regulated by a number of enzymes. The group of phosphatidylinositol 3-kinases (PI3K) 1 phosphorylates the lipid substrates PI, PI(4)P, and PI(4,5)P 2 at the 3-position of the inositol ring (1). The lipid product PI(3,4,5)P 3 has been strongly implicated to be important in chemotaxis in neutrophils and fibroblasts (2, 3). PTEN, identified as a tumor suppressor gene (4), reverses the action of PI3K by dephosphorylation of PI(3,4,5)P 3 and PI(3,4)P 2 at the 3-position (5). Another group of enzymes, the inositol 5-phosphatases, can remove the phosphate group at the 5-position of the inositol ring (6 -8). The importance of inositol 5-phosphatase activity in PI(3,4,5)P 3 regulation is demonstrated by SHIP1. In stimulated B-cells, SHIP1 accounts for the major phosphatase activity toward PI(3,4,5)P 3 , and inactivation of SHIP1 leads to an increased and prolonged PI(3,4,5)P 3 production (9). Other inositol 5-phosphatases have been shown to play important roles in a number of cellular processes. Mutations in the inositol 5-phosphatase OCRL are responsible for Lowe syndrome in human (10), and deletion of the presynaptic inositol 5-phosphatase Synaptojanin leads to neurological abnormalities and early death of mice (11).In the social amoeba, Dictyostelium discoideum chemotaxis toward folic acid and cAMP is an essential strategy for survival (12). Several observations suggest that phosphatidylinositol phosphates mediate chemotaxis and, in particular, the localization of the signal inside D. discoideum cells. The PH domains of a number of proteins involved in chemotaxis, including CRAC, Akt/PKB, and PhdA, have been shown to transiently localize at the leading edge of cells moving in a chemotactic gradient (13-15). As these PH domains bind to PI(3,4,5)P 3 and PI(3,4)P 2, an asymmetric lipid distribution is implicated by...

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Inactivation of Two Dictyostelium discoideum Genes, DdPIK1 and DdPIK2, Encoding Proteins Related to Mammalian Phosphatidylinositide 3-kinases, Results in Defects in Endocytosis, Lysosome to Postlysosome Transport, and Actin Cytoskeleton Organization

Cited by 98 publications

References 71 publications

An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway

An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway

Shear flow-induced motility ofDictyostelium discoideumcells on solid substrate

A Diverse Family of Inositol 5-Phosphatases Playing a Role in Growth and Development in Dictyostelium discoideum

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