Association of frabin with specific actin and membrane structures

Kim, Yongman; Ikeda, Wataru; Nakanishi, Hiroyuki; Tanaka, Yohsuke; Takekuni, Kyouji; Itoh, Shinsuke; Monden, Morito; Takai, Yoshimi

doi:10.1046/j.1365-2443.2002.00524.x

Cited by 22 publications

(20 citation statements)

References 19 publications

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“…Mutation of this residue in EEA1 abrogates endosomal localization, indicating that both FGD1 and FGD3 may have reduced affinity for phosphatidylinositol 3-phosphate and endosomes (43). FGD4, or Frabin, appears to have a conventional FYVE domain motif, but endosomal localization of this protein has not been described, perhaps due to the presence of an F-actin binding domain that may predominantly direct the protein to the actin cytoskeleton (44).…”

Section: Discussionmentioning

confidence: 99%

FGD2, a CDC42-specific Exchange Factor Expressed by Antigen-presenting Cells, Localizes to Early Endosomes and Active Membrane Ruffles

Huber¹,

Mårtensson²,

Bokoch

et al. 2008

Journal of Biological Chemistry

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Members of the Fgd (faciogenital dysplasia) gene family encode a group of critical guanine nucleotide exchange factors (GEFs), which, by specifically activating Cdc42, control cytoskeleton-dependent membrane rearrangements. In its first characterization, we find that FGD2 is expressed in antigen-presenting cells, including B lymphocytes, macrophages, and dendritic cells. In the B lymphocyte lineage, FGD2 levels change with developmental stage. In both mature splenic B cells and immature bone marrow B cells, FGD2 expression is suppressed upon activation through the B cell antigen receptor. FGD2 has a complex intracellular localization, with concentrations found in membrane ruffles and early endosomes. Although endosomal localization of FGD2 is dependent on a conserved FYVE domain, its C-terminal pleckstrin homology domain mediates recruitment to membrane ruffles. FGD2 overexpression promotes the activation of Cdc42 and leads to elevated JNK1 activity in a Cdc42-but not Rac1-dependent fashion. These findings are consistent with a role of FGD2 in leukocyte signaling and vesicle trafficking in cells specialized to present antigen in the immune system.

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Section: Discussionmentioning

confidence: 99%

FGD2, a CDC42-specific Exchange Factor Expressed by Antigen-presenting Cells, Localizes to Early Endosomes and Active Membrane Ruffles

Huber¹,

Mårtensson²,

Bokoch

et al. 2008

Journal of Biological Chemistry

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“…The biological function of this membrane association is still unknown, and expression of FGD2 lacking a functional FYVE domain still results in activation of JNK1 (Huber et al, 2008). Interestingly, FGD1 and frabin are both associated with the subcortical actin cytoskeleton (Estrada et al, 2001;Kim et al, 2002), and neither FGD1 nor frabin depends on the FYVE domain for intracellular localization. Nevertheless, the FYVE domain appears to be critical for function for frabin, because under low expression levels frabin constructs lacking this domain are unable to trigger the formation of filopodia (Ono et al, 2000).…”

Section: The Cdc42-specific Exchange Factor Don1 Localizes To Endosomesmentioning

confidence: 99%

Coordination of Cytokinesis and Cell Separation by Endosomal Targeting of a Cdc42-specific Guanine Nucleotide Exchange Factor inUstilago maydis

Schink

Bölker

2009

MBoC

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The small GTPase Cdc42 is a key regulator of cell polarity and cytoskeletal organization in most eukaryotic cells. In Ustilago maydis, Cdc42 and the guanine nucleotide exchange factor (GEF) Don1 regulate cytokinesis and cell separation. Don1 belongs to the FGD1 family of Cdc42-specific GEFs that are characterized by a C-terminal lipid-binding FYVE domain. Although the FGD1/frabin family of Rho-GEFs is evolutionary conserved from fungi to mammals the role of the FYVE domain for its biological function is unknown. Here, we show that the FYVE domain is specific for phosphatidylinositol-3-phosphate (PtdIns(3)P) and targets Don1 to endosomal vesicles. During cytokinesis asymmetric accumulation of Don1-containing vesicles occurs at the site of septation. We could show that FYVE-dependent localization is critical for the function of Don1 at normal expression levels but can be compensated for by overexpression of Don1 lacking a functional FYVE domain. Our results demonstrate that endosomal compartmentalization of a Cdc42-specific exchange factor is involved in the coordination of cytokinesis and cell separation. INTRODUCTIONSmall GTP-binding proteins of the Rho/Rac/Cdc42 family act as molecular switches in various biological processes, such as cytoskeleton reorganization, vesicular trafficking, and cell polarity (Jaffe and Hall, 2005). They cycle between two states: the active GTP-bound state and the inactive GDP-bound state. The switching between these states is regulated by interaction with accessory proteins. GTPaseactivating proteins (GAPs) promote hydrolysis of GTP and thus trigger inactivation of the GTP-binding protein (Bernards and Settleman, 2004). Guanine nucleotide exchange factors (GEFs) catalyze the release of GDP by stabilizing the nucleotide-free transition state (Rossman et al., 2005). This results in exchange of GDP by GTP because the latter nucleotide is much more abundant in the cytoplasm. Most GEFs specific for members of the Rho/Rac/Cdc42 family are characterized by the presence of the catalytic dbl homology (DH) domain and an associated lipid-binding pleckstrin homology (PH) domain (Rossman et al., 2005). Although many different GEFs of the Dbl family are known, only little is known about their spatial and temporal regulation (Erickson and Cerione, 2004). Recent studies indicate that interaction of the PH domain with specific phosphoinositides seems to play a role not only for association to the plasma membrane but also for allosteric regulation of GEF activity (Baumeister et al., 2006). Most members of the Dbl family contain additional domains that contribute to spatial and temporal regulation of GEF signaling. The mammalian Rac1-specific GEF Tiam1 contains a second PH domain located in the N-terminal region (Habets et al., 1994). Members of the FGD1/Frabin family are characterized by a C-terminal FYVE domain (Pasteris et al., 1994;Obaishi et al., 1998). FYVE domains consist of a cysteine-rich Zinc finger region, which mediates endomembrane association by interaction with phosphatidylinositol phos...

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“…Beyond the FYVE domain, there are no functional or structural similarities among these proteins, and they each have been hypothesized to fulfill distinct cellular functions (13,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30).…”

mentioning

confidence: 99%

Structural Basis for Endosomal Targeting by FYVE Domains

Hayakawa

Hayes²,

Lawe

et al. 2004

Journal of Biological Chemistry

104

116

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The FYVE domain is a conserved protein motif characterized by its ability to bind with high affinity and specificity to phosphatidylinositol 3-phosphate (PI(3)P), a phosphoinositide highly enriched in early endosomes. The PI(3)P polar head group contacts specific amino acid residues that are conserved among FYVE domains. Despite full conservation of these residues, the ability of different FYVE domains to bind to endosomes in cells is highly variable. Here we show that the endosomal localization in intact cells absolutely requires structural features intrinsic to the FYVE domain in addition to the PI(3)P binding pocket. These features are involved in FYVE domain dimerization and in interaction with the membrane bilayer. These interactions, which are determined by non-conserved residues, are likely to be essential for the temporal and spatial control of protein associations at the membrane-cytosol interface within the endocytic pathway.The FYVE domain is a double zinc finger named after the first four proteins found to contain this motif (Fab1, YotB, Vac1p, and EEA1) (1). FYVE domains bind with high specificity to phosphatidylinositol 3-phosphate (PI(3)P) 1 (2-5), which is highly enriched in early endosomes (3). Crystallographic and NMR analyses of isolated FYVE domains and crystallographic analysis of the homodimeric C terminus of EEA1 (6 -10) have revealed that six residues from the FYVE domain directly contact the Ins(1,3)P 2 group. These residues are localized within three conserved signature motifs, the WXXD, R(R/K)H-HCR, and RVC motifs.Although FYVE domains bind PI(3)P efficiently in vitro, when expressed in cells, isolated FYVE domains often fail to localize to endosomes (11)(12)(13)(14). Observations such as these have suggested that the ability of FYVE domains to localize to early endosomes may be determined by structural features distinct from those directly involved in PI(3)P binding (10). However, there is very little sequence conservation among FYVE domains in regions that do not directly contact the Ins(1,3)P 2 group. Thus, the molecular basis for the differing ability of FYVE domains to localize to endosomes remains unknown.To resolve this question, we have systematically analyzed the cellular localization of a series of isolated FYVE domains from the mammalian proteins EEA1, Hrs, SARA, FGD1, and frabin. Beyond the FYVE domain, there are no functional or structural similarities among these proteins, and they each have been hypothesized to fulfill distinct cellular functions (13,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30).With the exception of one residue in the FYVE domain of FGD1, all these FYVE domains contain the specific residues that directly contact PI(3)P, and all bind to PI(3)P in vitro. However, as shown here, the ability of these domains to interact with endosomes when expressed in intact cells varies greatly. A comparative analysis of the structural features within these FYVE domains that correlate with in vivo endosome binding reveals a crucial role for two variable...

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Association of frabin with specific actin and membrane structures

Cited by 22 publications

References 19 publications

FGD2, a CDC42-specific Exchange Factor Expressed by Antigen-presenting Cells, Localizes to Early Endosomes and Active Membrane Ruffles

FGD2, a CDC42-specific Exchange Factor Expressed by Antigen-presenting Cells, Localizes to Early Endosomes and Active Membrane Ruffles

Coordination of Cytokinesis and Cell Separation by Endosomal Targeting of a Cdc42-specific Guanine Nucleotide Exchange Factor inUstilago maydis

Structural Basis for Endosomal Targeting by FYVE Domains

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