FH3, A Domain Found in Formins, Targets the Fission Yeast Formin Fus1 to the Projection Tip During Conjugation

Petersen, Janni; Nielsen, Olaf; Egel, Richard; Hagan, Iain

doi:10.1083/jcb.141.5.1217

Cited by 157 publications

(163 citation statements)

References 59 publications

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Section: Introductionmentioning

confidence: 99%

“…The FH1 region is a proline-rich stretch that recruits profilin, an actin-monomer binding protein essential for formin function in vivo , to participate in FH2-mediated nucleation in vitro (Sagot et al, 2002b;Kovar et al, 2003;Pring et al, 2003). Other regions present in Bni1p and Bnr1p are a regulatory NH 2 -terminal rho-GTPase-binding domain that subjects many formins to rho-dependent activation (Kohno et al, 1996;Evangelista et al, 1997;Imamura et al, 1997;Dong et al, 2003), and an FH3 motif that helps localize formins within the cell (Petersen et al, 1998).With loss of formin function, actin cables disassemble in 2 min, and a cytokinetic ring is unable to assemble, but actin patches remain intact Sagot et al, 2002a;Tolliday et al, 2002). Other actin nucleators, particularly the Arp2/3 complex, play no apparent role in cable or cytokinetic ring assembly in budding yeast (Winter et al, 1999;Evangelista et al, 2002;Tolliday et al, 2002), suggesting the formins might be in vivo nucleators for these actin filaments.…”

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confidence: 99%

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Stable and Dynamic Axes of Polarity Use Distinct Formin Isoforms in Budding Yeast

Pruyne

Gao

et al. 2004

MBoC

151

208

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Bud growth in yeast is guided by myosin-driven delivery of secretory vesicles from the mother cell to the bud. We find transport occurs along two sets of actin cables assembled by two formin isoforms. The Bnr1p formin assembles cables that radiate from the bud neck into the mother, providing a stable mother-bud axis. These cables also depend on septins at the neck and are required for efficient transport from the mother to the bud. The Bni1p formin assembles cables that line the bud cortex and target vesicles to varying locations in the bud. Loss of these cables results in morphological defects as vesicles accumulate at the neck. Assembly of these cables depends on continued polarized secretion, suggesting vesicular transport provides a positive feedback signal for Bni1p activation, possibly by rho-proteins. By coupling different formin isoforms to unique cortical landmarks, yeast uses common cytoskeletal elements to maintain stable and dynamic axes in the same cell. INTRODUCTIONProper cell polarization requires a balance between dynamism and stability. Persistent systems, such as the apical and basolateral domains of epithelial cells, show a higher stability than flexible systems, such as cells undergoing chemotaxis. However, both types can use similar cytoskeletal components, so an important task in understanding the control of polarity is to identify features that influence persistence, and how those features integrate with the core cytoskeletal machinery providing the physical expression of polarity.The process of bud growth of the yeast Saccharomyces cerevisiae provides a model for examining the control of polarity (for reviews, see Bretscher, 2003;Chang and Peter, 2003). Secretory organelles, such as the Golgi and endoplasmic reticulum, are distributed throughout the bud and mother cell, whereas post-Golgi secretory vesicles concentrate at discrete growth sites at the cell cortex. These vesicles are guided to these sites along what are essentially two axes of polarity: a stable axis directing traffic from the mother into the bud, and a dynamic axis that fine-tunes delivery from the bud neck to specific regions in the bud, sending vesicles first to the small bud tip, then to the entire bud surface, and finally back toward the neck during mother/daughter separation. On delivery to these locations, post-Golgi vesicles fuse with the cell surface to promote localized cell expansion.Two class-V myosins, with heavy chains encoded by MYO2 (Johnston et al., 1991) and MYO4 (Haarer et al., 1994), propel cellular components, including vesicles, organelles, mRNAs, and microtubules, from the mother into the bud during growth and organelle segregation. The myosins move along cables of actin filaments that radiate throughout the cell in arrays oriented toward growth sites (Adams and Pringle, 1984;Kilmartin and Adams, 1984).Assembly of these cables depends on two formin homologues, Bni1p and Bnr1p (Evangelista et al., 2002;Sagot et al., 2002a), members of a family of cytoskeletal regulatory proteins defined by conserved fo...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Stable and Dynamic Axes of Polarity Use Distinct Formin Isoforms in Budding Yeast

Pruyne

Gao

et al. 2004

MBoC

151

208

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“…In Schizosaccharomyces pombe, three formins exist which are also involved in cell polarity and cytokinesis. The protein SpCdc12p is involved in cytokinesis (Chang et al, 1997;Kovar et al, 2003), SpFus1p in cell fusion (Petersen et al, 1998b) and SpFor3p in cell polarity control via regulation of the actin and microtubule network (Feierbach and Chang, 2001;Nakano et al, 2002). The only formin family member described so far in a filamentous fungus is the SepA protein of Aspergillus nidulans.…”

Section: Introductionmentioning

confidence: 99%

From Function to Shape: A Novel Role of a Formin in Morphogenesis of the FungusAshbya gossypii

Schmitz

Kaufmann

Köhli

et al. 2006

MBoC

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Morphogenesis of filamentous ascomycetes includes continuously elongating hyphae, frequently emerging lateral branches, and, under certain circumstances, symmetrically dividing hyphal tips. We identified the formin AgBni1p of the model fungus Ashbya gossypii as an essential factor in these processes. AgBni1p is an essential protein apparently lacking functional overlaps with the two additional A. gossypii formins that are nonessential. Agbni1 null mutants fail to develop hyphae and instead expand to potato-shaped giant cells, which lack actin cables and thus tip-directed transport of secretory vesicles. Consistent with the essential role in hyphal development, AgBni1p locates to tips, but not to septa. The presence of a diaphanous autoregulatory domain (DAD) indicates that the activation of AgBni1p depends on Rho-type GTPases. Deletion of this domain, which should render AgBni1p constitutively active, completely changes the branching pattern of young hyphae. New axes of polarity are no longer established subapically (lateral branching) but by symmetric divisions of hyphal tips (tip splitting). In wild-type hyphae, tip splitting is induced much later and only at much higher elongation speed. When GTP-locked Rho-type GTPases were tested, only the young hyphae with mutated AgCdc42p split at their tips, similar to the DAD deletion mutant. Two-hybrid experiments confirmed that AgBni1p interacts with GTP-bound AgCdc42p. These data suggest a pathway for transforming one axis into two new axes of polar growth, in which an increased activation of AgBni1p by a pulse of activated AgCdc42p stimulates additional actin cable formation and tip-directed vesicle transport, thus enlarging and ultimately splitting the polarity site.

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“…Formin has a proline-rich domain and a 130-amino acid region that have been named FH1 and FH2 domains, respectively (24). A third region, the FH3 domain, is an amino-terminal domain that is the least conserved FH domain among formin family members (25). Diaphanous-related formin homology proteins such as mDia1, mDia2, and yeast Bni1p contain all three FH (24) as well as an amino terminus GTPase binding domain (RhoA binding domain) (20) and a carboxyl terminus interaction domain termed Dia autoregulatory domain (DAD domain) (26).…”

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confidence: 99%

PKD2 Interacts and Co-localizes with mDia1 to Mitotic Spindles of Dividing Cells

Rundle

Gorbsky

Tsiokas

2004

Journal of Biological Chemistry

110

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Mutations in pkd2 result in the type 2 form of autosomal dominant polycystic kidney disease, which accounts for ϳ15% of all cases of the disease. PKD2, the protein product of pkd2, belongs to the transient receptor potential superfamily of cation channels, and it can function as a mechanosensitive channel in the primary cilium of kidney cells, an intracellular Ca 2؉ release channel in the endoplasmic reticulum, and/or a nonselective cation channel in the plasma membrane. We have identified mDia1/Drf1 (mammalian Diaphanous or Diaphanous-related formin 1 protein) as a PKD2-interacting protein by yeast two-hybrid screen. mDia1 is a member of the RhoA GTPase-binding formin homology protein family that participates in cytoskeletal organization, cytokinesis, and signal transduction. We show that mDia1 and PKD2 interact in native and in transfected cells, and binding is mediated by the cytoplasmic C terminus of PKD2 binding to the mDia1 N terminus. The interaction is more prevalent in dividing cells in which endogenous PKD2 and mDia1 co-localize to the mitotic spindles. RNA interference experiments reveal that endogenous mDia1 knockdown in HeLa cells results in the loss of PKD2 from mitotic spindles and alters intracellular Ca 2؉ release. Our results suggest that mDia1 facilitates the movement of PKD2 to a centralized position during cell division and has a positive effect on intracellular Ca 2؉ release during mitosis. This may be important to ensure equal segregation of PKD2 to the daughter cell to maintain a necessary level of channel activity. Alternatively, PKD2 channel activity may be important in the cell division process or in cell fate decisions after division.

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FH3, A Domain Found in Formins, Targets the Fission Yeast Formin Fus1 to the Projection Tip During Conjugation

Cited by 157 publications

References 59 publications

Stable and Dynamic Axes of Polarity Use Distinct Formin Isoforms in Budding Yeast

Stable and Dynamic Axes of Polarity Use Distinct Formin Isoforms in Budding Yeast

From Function to Shape: A Novel Role of a Formin in Morphogenesis of the FungusAshbya gossypii

PKD2 Interacts and Co-localizes with mDia1 to Mitotic Spindles of Dividing Cells

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