The novel RacE-binding protein GflB sharpens Ras activity at the leading edge of migrating cells

Senoo, Hiroshi; Cai, Huaqing; Wang, Yu; Sesaki, Hiromi; Iijima, Miho

doi:10.1091/mbc.e15-11-0796

Cited by 15 publications

(28 citation statements)

References 63 publications

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“…S2E, Movie 13) and became mono-nucleated. In contrast, gflB-KO cells formed multinucleated cells and scarcely grew in suspension culture, similar to myosin II-KO cells (Senoo et al, 2016). This similarity of phenotype suggests that GflB is involved in cellular processes regulated by myosin II.…”

Section: Failure Of Cytokinesis At Abscission In Gflb-ko and Gfp-gflbmentioning

confidence: 81%

“…The GEF-like protein B (GflB) of D. discoideum is a recently identified Rap1GEF involved in chemotaxis (Liu et al, 2016;Senoo et al, 2016). During chemotaxis, GflB acts as an effector of Gα2 subunits: active Gα2 releases an auto-inhibition of GflB and in turn GflB exerts GEF activity towards Rap1 (Liu et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…During chemotaxis, GflB acts as an effector of Gα2 subunits: active Gα2 releases an auto-inhibition of GflB and in turn GflB exerts GEF activity towards Rap1 (Liu et al, 2016). In addition to the RasGEF domains (RasGEFN and RasGEFC), GflB also has an N-terminal lipid-binding and inactive Rho GAP domains that can interact with several Rac GTPases, including Rac1, RacB, RacE and RacL, regardless of its activation status (Liu et al, 2016;Senoo et al, 2016). These domains may contribute to the correct localization of GflB.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The F-actin-binding RapGEF GflB is required for efficient macropinocytosis in Dictyostelium

Inaba

Yoda

Adachi

2017

Journal of Cell Science

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Macropinocytosis involves the uptake of large volumes of fluid, which is regulated by various small GTPases. The protein GflB is a guanine nucleotide exchange factor (GEF) of Rap1, and is involved in chemotaxis. Here, we studied the role of GflB in macropinocytosis, phagocytosis and cytokinesis. In plate culture of vegetative cells, compared with the parental strain AX2,-knockout (KO) cells were flatter and more polarized, whereas GflB-overproducing cells were rounder. The -KO cells exhibited impaired crown formation and retraction, particularly retraction, resulting in more crowns (macropinocytic cups) per cell and longer crown lifetimes. Accordingly,-KO cells showed defects in macropinocytosis and also in phagocytosis and cytokinesis. F-actin levels were elevated in -KO cells. GflB localized to the actin cortex most prominently at crowns and phagocytic cups. The villin headpiece domain (VHP)-like N-terminal domain of GflB directly interacted with F-actin Furthermore, a domain enriched in basic amino acids interacted with specific membrane cortex structures such as the cleavage furrow. In conclusion, GflB acts as a key local regulator of actin-driven membrane protrusion possibly by modulating Rap1 signaling pathways.

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Section: Failure Of Cytokinesis At Abscission In Gflb-ko and Gfp-gflbmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The F-actin-binding RapGEF GflB is required for efficient macropinocytosis in Dictyostelium

Inaba

Yoda

Adachi

2017

Journal of Cell Science

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“…We next quantitated Ras activation in wild-type and gflB À cells using pull-down assays with GST-Raf1-RBD or GST-Byr2 as bait, and Ras activation was imaged in vivo with a Raf1-RBD-GFP marker as described previously (Kortholt et al, 2011). GST-Raf1-RBD preferentially binds RasG and RasB, while GST-Byr2 binds strongest to RasC (Kae et al, 2004;Zhang et al, 2008). Wild-type cells exhibit a low basal level of Ras-GTP, which rises rapidly in response to global chemoattractant stimulation with a peak at $5 s and then returns quickly to basal levels ( Figures 2E and 2F).…”

Section: Gflb -Cells Exhibit Decreased Rap1 and Increased Ras Activationmentioning

confidence: 99%

A Gα-Stimulated RapGEF Is a Receptor-Proximal Regulator of Dictyostelium Chemotaxis

et al. 2016

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Chemotaxis, or directional movement toward extracellular chemical gradients, is an important property of cells that is mediated through G-protein-coupled receptors (GPCRs). Although many chemotaxis pathways downstream of Gβγ have been identified, few Gα effectors are known. Gα effectors are of particular importance because they allow the cell to distinguish signals downstream of distinct chemoattractant GPCRs. Here we identify GflB, a Gα2 binding partner that directly couples the Dictyostelium cyclic AMP GPCR to Rap1. GflB localizes to the leading edge and functions as a Gα-stimulated, Rap1-specific guanine nucleotide exchange factor required to balance Ras and Rap signaling. The kinetics of GflB translocation are fine-tuned by GSK-3 phosphorylation. Cells lacking GflB display impaired Rap1/Ras signaling and actin and myosin dynamics, resulting in defective chemotaxis. Our observations demonstrate that GflB is an essential upstream regulator of chemoattractant-mediated cell polarity and cytoskeletal reorganization functioning to directly link Gα activation to monomeric G-protein signaling.

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“…From a molecular point of view, the amoebas' locomotion is controlled by complex metabolic networks, which operate as non-linear systems with dynamics far from equilibrium 16 . These biochemical networks involve an intricate interplay of multiple components of the cell migration machinery, including the actin cytoskeleton, ion channels, transporters, regulatory proteins such as the Arp2/3 complex or the ADF/cofilin family proteins 17,18 . As a consequence of the efficient self-regulatory activity of the metabolic networks, each amoeba seems to be endowed with the ability to orientate its movement toward specific goals in the external environment, thereby developing efficient foraging strategies even in conditions of sparse resources when there is limited or no information as to where food is located.…”

Section: Discussionmentioning

confidence: 99%

Long-term memory in the migration movements of enucleatedAmoeba proteus

Bringas

Malaina

Pérez-Samartı́n

et al. 2017

Preprint

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How motile, free unicellular organisms maximize the rate at which they encounter resources and develop optimal search strategies remains largely unknown. In fact, cell foraging is a very complex activity in which unicellular organisms integrate a diversity of external cues and develop efficient systemic movements to localize nourishment. These foraging strategies are critical when cells face conditions of scarce resources or they don't possess information on where food is located. Here, in order to determine whether nuclear activity is directly involved in cell migration, we placed single, well-isolated, enucleated and non-enucleated starved Amoeba proteus on nutrient-free petri dishes, and we then analyzed their trajectories of movement using non-linear dynamic tools. We found that despite being enucleated, the systemic responses of the protoplasm exhibited typical biological behaviors, moving with apparent normality, creeping along the substrate, developing pseudopodia and gobbling up prey. Our quantitative studies show that both the non-enucleated and enucleated amoebas display a similar migration structure, characterized by super-diffusivity, non-trivial long-term correlations and move-step fluctuations with scale invariant properties. In conclusion, the nuclear activity does not seem to directly control the systemic cellular movements involved in locating sparse resources.

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The novel RacE-binding protein GflB sharpens Ras activity at the leading edge of migrating cells

Cited by 15 publications

References 63 publications

The F-actin-binding RapGEF GflB is required for efficient macropinocytosis in Dictyostelium

The F-actin-binding RapGEF GflB is required for efficient macropinocytosis in Dictyostelium

A Gα-Stimulated RapGEF Is a Receptor-Proximal Regulator of Dictyostelium Chemotaxis

Long-term memory in the migration movements of enucleatedAmoeba proteus

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