A novel phosphatidylinositol 4,5-bisphosphate-binding domain targeting the Phg2 kinase to the membrane in Dictyostelium cells

Blanc, Cédric; Charette, Steve J.; Cherix, Nathalie; Lefkir, Yaya; Cosson, Pierre; Letourneur, François

doi:10.1016/j.ejcb.2005.09.014

Cited by 15 publications

(11 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5D), in agreement with previous studies indicating that acidification of macropinosomes is initiated approximately 1 minute after closure of macropinosomes, when CRAC-GFP is no longer associated with the macropinosome (Blanc et al, 2005;Maniak, 2003). Together, these results indicate that the pattern of membrane proteins found in newly formed macropinosomes was identical to that seen in newly formed phagosomes.…”

Section: Similar Sorting Patterns In Phagosomes and Macropinosomessupporting

confidence: 81%

“…In Dictyostelium, macropinocytic cups and macropinosomes form constantly, and they can be revealed by the recruitment of CRAC-GFP. Live analysis of macropinocytosis revealed that the CRAC-GFP-positive vacuoles in Dictyostelium cells correspond to newly formed macropinosomes (<1 minute) (Blanc et al, 2005). Since newly formed macropinosomes can be identified in this manner, their membrane composition can be analyzed by immunofluorescence.…”

Section: Similar Sorting Patterns In Phagosomes and Macropinosomesmentioning

confidence: 99%

“…For live microscopy, wild-type cells expressing CRAC-GFP were attached to a glass coverslip for 3 hours in low-fluorescence medium as already described (Blanc et al, 2005). They were then observed using a confocal microscope equipped with a dual-disc micro-lens scanner (QLC100 Confocal Scanner, Visitron Systems, Puchheim, Germany).…”

Section: Cells and Reagentsmentioning

confidence: 99%

See 2 more Smart Citations

Selective membrane exclusion in phagocytic and macropinocytic cups

Mercanti

Charette

Bennett

et al. 2006

Journal of Cell Science

Self Cite

View full text Add to dashboard Cite

Specialized eukaryotic cells can ingest large particles and sequester them within membrane-delimited phagosomes. Many studies have described the delivery of lysosomal proteins to the phagosome, but little is known about membrane sorting during the early stages of phagosome formation. Here we used Dictyostelium discoideum amoebae to analyze the membrane composition of newly formed phagosomes. The membrane delimiting the closing phagocytic cup was essentially derived from the plasma membrane, but a subgroup of proteins was specifically excluded. Interestingly the same phenomenon was observed during the formation of macropinosomes, suggesting that the same sorting mechanisms are at play during phagocytosis and macropinocytosis. Analysis of mutant strains revealed that clathrin-associated adaptor complexes AP-1, -2 and -3 were not necessary for this selective exclusion and, accordingly, ultrastructural analysis revealed no evidence for vesicular transport around phagocytic cups. Our results suggest the existence of a new, as yet uncharacterized, sorting mechanism in phagocytic and macropinocytic cups

show abstract

Section: Similar Sorting Patterns In Phagosomes and Macropinosomessupporting

confidence: 81%

Section: Similar Sorting Patterns In Phagosomes and Macropinosomesmentioning

confidence: 99%

See 1 more Smart Citation

Selective membrane exclusion in phagocytic and macropinocytic cups

Mercanti

Charette

Bennett

et al. 2006

Journal of Cell Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…Phg2 also contains a serine/threonine-specific kinase and prolinerich repeats and plays an important role in substrate adhesion, cellular adhesion, phagocytosis, actin cytoskeleton reorganization, and motility (19). Recently Blánc et al (46) identified a new inositol 4,5-diphosphate binding domain that is essential and sufficient for the membrane localization of Phg2 and that this membrane localization is necessary for proper functioning of the protein. This inositol 4,5-diphosphate binding domain comprises amino acids 81-193, distal from the RA and kinase domains.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the GbpD-activated Rap1 Pathway Regulating Adhesion and Cell Polarity in Dictyostelium discoideum

Kortholt

Rehmann

Kae

et al. 2006

Journal of Biological Chemistry

View full text Add to dashboard Cite

The regulation of cell polarity plays an important role in chemotaxis. GbpD, a putative nucleotide exchange factor for small G-proteins of the Ras family, has been implicated in adhesion, cell polarity, and chemotaxis in Dictyostelium. Cells overexpressing GbpD are flat, exhibit strongly increased cell-substrate attachment, and extend many bifurcated and lateral pseudopodia. These cells overexpressing GbpD are severely impaired in chemotaxis, most likely due to the induction of many protrusions rather than an enhanced adhesion. The GbpD-overexpression phenotype is similar to that of cells overexpressing Rap1. Here we demonstrate that GbpD activates Rap1 both in vivo and in vitro but not any of the five other characterized Ras proteins. In a screen for Rap1 effectors, we overexpressed GbpD in several mutants defective in adhesion or cell polarity and identified Phg2 as Rap1 effector necessary for adhesion, but not cell polarity. Phg2, a serine/threonine-specific kinase, directly interacts with Rap1 via its Ras association domain.

show abstract

“…An actin coat is required for phagosome and macropinosome formation, and is immediately disassembled upon internalization of the vesicle (Insall et al, 2001;Maniak et al, 1995;Peracino et al, 1998). Actin depolymerization correlates with the disappearance of PtdIns(4,5)P 2 from the closing phagosome or macropinosome, which might be due to the activity of enzymes such as PLC, PI3K or the OCRL1 homolog Dd5P4 phosphatase (Blanc et al, 2005;Bozzaro et al, 2008;Dormann et al, 2004;Loovers et al, 2007). The impaired uptake of Legionella upon inactivation of PLC or PI3K can be fully explained with the regulatory activity of these enzymes on actin depolymerization.…”

Section: Actin Assembly Is Required For Legionella Uptake But Not Fomentioning

confidence: 99%

Phosphoinositides differentially regulate bacterial uptake and Nramp1-induced resistance toLegionellainfection inDictyostelium

Peracino

Balest

Bozzaro

2010

Journal of Cell Science

View full text Add to dashboard Cite

SummaryMembrane phosphatidylinositides recruit cytosolic proteins to regulate phagocytosis, macropinocytosis and endolysosomal vesicle maturation. Here, we describe effects of inactivation of PI3K, PTEN or PLC on Escherichia coli and Legionella pneumophila uptake by the professional phagocyte Dictyostelium discoideum. We show that L. pneumophila is engulfed by macropinocytosis, a process that is partially sensitive to PI3K inactivation, unlike phagocytosis of E. coli. Both processes are blocked by PLC inhibition. Whereas E. coli is rapidly digested, Legionella proliferates intracellularly. Proliferation is blocked by constitutively expressing Nramp1, an endolysosomal iron transporter that confers resistance against invasive bacteria. Inactivation of PI3K, but not PTEN or PLC, enhances Legionella infection and suppresses the protective effect of Nramp1 overexpression. PI3K activity is restricted to early infection and is not mediated by effects on the actin cytoskeleton; rather L. pneumophila, in contrast to E. coli, subverts phosphoinositide-sensitive fusion of Legionella-containing macropinosomes with acidic vesicles, without affecting Nramp1 recruitment. A model is presented to explain how Legionella escapes fusion with acidic vesicles and Nramp1-induced resistance to pathogens.

show abstract

A novel phosphatidylinositol 4,5-bisphosphate-binding domain targeting the Phg2 kinase to the membrane in Dictyostelium cells

Cited by 15 publications

References 40 publications

Selective membrane exclusion in phagocytic and macropinocytic cups

Selective membrane exclusion in phagocytic and macropinocytic cups

Characterization of the GbpD-activated Rap1 Pathway Regulating Adhesion and Cell Polarity in Dictyostelium discoideum

Phosphoinositides differentially regulate bacterial uptake and Nramp1-induced resistance toLegionellainfection inDictyostelium

Contact Info

Product

Resources

About