scholarly journals A WASp-binding type II phosphatidylinositol 4-kinase required for actin polymerization-driven endosome motility

2005 ◽  
Vol 171 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Fanny S. Chang ◽  
Gil-Soo Han ◽  
George M. Carman ◽  
Kendall J. Blumer
Keyword(s):  
Plasma Membrane ◽  
Actin Filament ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Type Ii ◽  
Activation Domain ◽  
Cargo Protein ◽  
Phosphatidylinositol 4 ◽  
Syndrome Protein ◽  
Binding Type

Endosomes in yeast have been hypothesized to move through the cytoplasm by the momentum gained after actin polymerization has driven endosome abscision from the plasma membrane. Alternatively, after abscission, ongoing actin polymerization on endosomes could power transport. Here, we tested these hypotheses by showing that the Arp2/3 complex activation domain (WCA) of Las17 (Wiskott-Aldrich syndrome protein [WASp] homologue) fused to an endocytic cargo protein (Ste2) rescued endosome motility in las17ΔWCA mutants, and that capping actin filament barbed ends inhibited endosome motility but not endocytic internalization. Motility therefore requires continual actin polymerization on endosomes. We also explored how Las17 is regulated. Endosome motility required the Las17-binding protein Lsb6, a type II phosphatidylinositol 4-kinase. Catalytically inactive Lsb6 interacted with Las17 and promoted endosome motility. Lsb6 therefore is a novel regulator of Las17 that mediates endosome motility independent of phosphatidylinositol 4-phosphate synthesis. Mammalian type II phosphatidylinositol 4-kinases may regulate WASp proteins and endosome motility.

scholarly journals Dia1 and IQGAP1 interact in cell migration and phagocytic cup formation

2007 ◽  
Vol 178 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Dominique T. Brandt ◽  
Sabrina Marion ◽  
Gareth Griffiths ◽  
Takashi Watanabe ◽  
Kozo Kaibuchi ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Filament ◽  
Cell Shape ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Subcellular Location ◽  
Scaffold Protein ◽  
Cellular Location ◽  
Inhibitory Domain ◽  
Migrating Cells

The Diaphanous-related formin Dia1 nucleates actin polymerization, thereby regulating cell shape and motility. Mechanisms that control the cellular location of Dia1 to spatially define actin polymerization are largely unknown. In this study, we identify the cytoskeletal scaffold protein IQGAP1 as a Dia1-binding protein that is necessary for its subcellular location. IQGAP1 interacts with Dia1 through a region within the Diaphanous inhibitory domain after the RhoA-mediated release of Dia1 autoinhibition. Both proteins colocalize at the front of migrating cells but also at the actin-rich phagocytic cup in macrophages. We show that IQGAP1 interaction with Dia1 is required for phagocytosis and phagocytic cup formation. Thus, we identify IQGAP1 as a novel component involved in the regulation of phagocytosis by mediating the localization of the actin filament nucleator Dia1.

scholarly journals Maintenance of Hormone-sensitive Phosphoinositide Pools in the Plasma Membrane Requires Phosphatidylinositol 4-Kinase IIIα

2008 ◽  
Vol 19 (2) ◽  
pp. 711-721 ◽  
Author(s):  
Andras Balla ◽  
Yeun Ju Kim ◽  
Peter Varnai ◽  
Zsofia Szentpetery ◽  
Zachary Knight ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Small Interfering Rna ◽  
Type Ii ◽  
Measurable Effect ◽  
Down Regulation ◽  
Type Iii ◽  
Hormone Sensitive ◽  
Phosphatidylinositol 4 ◽  
Interfering Rna

Type III phosphatidylinositol (PtdIns) 4-kinases (PI4Ks) have been previously shown to support plasma membrane phosphoinositide synthesis during phospholipase C activation and Ca2+ signaling. Here, we use biochemical and imaging tools to monitor phosphoinositide changes in the plasma membrane in combination with pharmacological and genetic approaches to determine which of the type III PI4Ks (α or β) is responsible for supplying phosphoinositides during agonist-induced Ca2+ signaling. Using inhibitors that discriminate between the α- and β-isoforms of type III PI4Ks, PI4KIIIα was found indispensable for the production of phosphatidylinositol 4-phosphate (PtdIns4P), phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], and Ca2+ signaling in angiotensin II (AngII)-stimulated cells. Down-regulation of either the type II or type III PI4K enzymes by small interfering RNA (siRNA) had small but significant effects on basal PtdIns4P and PtdIns(4,5)P2 levels in 32P-labeled cells, but only PI4KIIIα down-regulation caused a slight impairment of PtdIns4P and PtdIns(4,5)P2 resynthesis in AngII-stimulated cells. None of the PI4K siRNA treatments had a measurable effect on AngII-induced Ca2+ signaling. These results indicate that a small fraction of the cellular PI4K activity is sufficient to maintain plasma membrane phosphoinositide pools, and they demonstrate the value of the pharmacological approach in revealing the pivotal role of PI4KIIIα enzyme in maintaining plasma membrane phosphoinositides.

scholarly journals Essential and unique roles of PIP5K-γ and -α in Fcγ receptor-mediated phagocytosis

2009 ◽  
Vol 184 (2) ◽  
pp. 281-296 ◽  
Author(s):  
Yuntao S. Mao ◽  
Masaki Yamaga ◽  
Xiaohui Zhu ◽  
Yongjie Wei ◽  
Hui-Qiao Sun ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Type I ◽  
Dependent Manner ◽  
Fcγ Receptor ◽  
Protein Activation ◽  
Phosphatidylinositol 4 ◽  
Syndrome Protein ◽  
Pharmacological Manipulations

The actin cytoskeleton is dynamically remodeled during Fcγ receptor (FcγR)-mediated phagocytosis in a phosphatidylinositol (4,5)-bisphosphate (PIP2)-dependent manner. We investigated the role of type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) γ and α isoforms, which synthesize PIP2, during phagocytosis. PIP5K-γ−/− bone marrow–derived macrophages (BMM) have a highly polymerized actin cytoskeleton and are defective in attachment to IgG-opsonized particles and FcγR clustering. Delivery of exogenous PIP2 rescued these defects. PIP5K-γ knockout BMM also have more RhoA and less Rac1 activation, and pharmacological manipulations establish that they contribute to the abnormal phenotype. Likewise, depletion of PIP5K-γ by RNA interference inhibits particle attachment. In contrast, PIP5K-α knockout or silencing has no effect on attachment but inhibits ingestion by decreasing Wiskott-Aldrich syndrome protein activation, and hence actin polymerization, in the nascent phagocytic cup. In addition, PIP5K-γ but not PIP5K-α is transiently activated by spleen tyrosine kinase–mediated phosphorylation. We propose that PIP5K-γ acts upstream of Rac/Rho and that the differential regulation of PIP5K-γ and -α allows them to work in tandem to modulate the actin cytoskeleton during the attachment and ingestion phases of phagocytosis.

scholarly journals Type II Phosphatidylinositol 4-Kinase β Is a Cytosolic and Peripheral Membrane Protein That Is Recruited to the Plasma Membrane and Activated by Rac-GTP

2002 ◽  
Vol 277 (48) ◽  
pp. 46586-46593 ◽  
Author(s):  
Yong Jie Wei ◽  
Hui Qiao Sun ◽  
Masaya Yamamoto ◽  
Pawel Wlodarski ◽  
Kaiko Kunii ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Type Ii ◽  
Peripheral Membrane Protein ◽  
Phosphatidylinositol 4

scholarly journals Processive acceleration of actin barbed-end assembly by N-WASP

2014 ◽  
Vol 25 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Nimisha Khanduja ◽  
Jeffrey R. Kuhn
Keyword(s):  
Actin Filament ◽  
Actin Polymerization ◽  
Similar Rate ◽  
Diffusion Limited ◽  
Model Cell ◽  
Filament Bundles ◽  
High Filament ◽  
Basement Layer ◽  
Syndrome Protein ◽  
Assembly Activity

Neuronal Wiskott–Aldrich syndrome protein (N-WASP)–activated actin polymerization drives extension of invadopodia and podosomes into the basement layer. In addition to activating Arp2/3, N-WASP binds actin-filament barbed ends, and both N-WASP and barbed ends are tightly clustered in these invasive structures. We use nanofibers coated with N-WASP WWCA domains as model cell surfaces and single-actin-filament imaging to determine how clustered N-WASP affects Arp2/3-independent barbed-end assembly. Individual barbed ends captured by WWCA domains grow at or below their diffusion-limited assembly rate. At high filament densities, however, overlapping filaments form buckles between their nanofiber tethers and myosin attachment points. These buckles grew ∼3.4-fold faster than the diffusion-limited rate of unattached barbed ends. N-WASP constructs with and without the native polyproline (PP) region show similar rate enhancements in the absence of profilin, but profilin slows barbed-end acceleration from constructs containing the PP region. Increasing Mg2+ to enhance filament bundling increases the frequency of filament buckle formation, consistent with a requirement of accelerated assembly on barbed-end bundling. We propose that this novel N-WASP assembly activity provides an Arp2/3-independent force that drives nascent filament bundles into the basement layer during cell invasion.

scholarly journals Hermansky-Pudlak Syndrome Protein Complexes Associate with Phosphatidylinositol 4-Kinase Type II α in Neuronal and Non-neuronal Cells

2008 ◽  
Vol 284 (3) ◽  
pp. 1790-1802 ◽  
Author(s):  
Gloria Salazar ◽  
Stephanie Zlatic ◽  
Branch Craige ◽  
Andrew A. Peden ◽  
Jan Pohl ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Neuronal Cells ◽  
Type Ii ◽  
Hermansky Pudlak Syndrome ◽  
Phosphatidylinositol 4 ◽  
Syndrome Protein

TF1, the bacteriophage SPO1-encoded type II DNA-binding protein, is essential for viral multiplication.

1988 ◽  
Vol 62 (9) ◽  
pp. 3455-3462 ◽  
Author(s):  
M H Sayre ◽  
E P Geiduschek
Keyword(s):  
Dna Binding ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Type Ii ◽  
Viral Multiplication
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