The diaphanous-related formin DAAM1 collaborates with the Rho GTPases RhoA and Cdc42, CIP4 and Src in regulating cell morphogenesis and actin dynamics

Ludwig Institute for Cancer Research, Biomedical Center, Uppsala University, Box 595, S-751 24 Uppsala, Sweden.
Experimental Cell Research (Impact Factor: 3.25). 08/2006; 312(12):2180-94. DOI: 10.1016/j.yexcr.2006.03.013
Source: PubMed


Binding partners for the Cdc42 effector CIP4 were identified by the yeast two-hybrid system, as well as by testing potential CIP4-binding proteins in coimmunoprecipitation experiments. One of the CIP4-binding proteins, DAAM1, was characterised in more detail. DAAM1 is a ubiquitously expressed member of the mammalian diaphanous-related formins, which include proteins such as mDia1 and mDia2. DAAM1 was shown to bind to the SH3 domain of CIP4 in vivo. Ectopically expressed DAAM1 localised in dotted pattern at the dorsal side of transfected cells and the protein was accumulated in the proximity to the microtubule organising centre. Moreover, ectopic expression of DAAM1 induced a marked alteration of the cell morphology, seen as rounding up of the cells, the formation of branched protrusions as well as a reduction of stress-fibres in the transfected cells. Coimmunoprecipitation experiments demonstrated that DAAM1 bound to RhoA and Cdc42 in a GTP-dependent manner. Moreover, DAAM1 was found to interact and collaborate with the non-receptor tyrosine kinase Src in the formation of branched protrusions. Taken together, our data indicate that DAAM1 communicates with Rho GTPases, CIP4 and Src in the regulation of the signalling pathways that co-ordinate the dynamics of the actin filament system.

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    • "To our knowledge, this is the first functional evidence supporting the participation of the actin cytoskeleton in nuclear-centrosomal interaction, and is in line with our hypothesis, suggesting that CIP4 presence at the centrosome is necessary for disengaging the centrosome from the nucleus by allowing actin remodeling. On this regard, CIP4 interacts with DAAM1, which is a formin belonging to the diaphanous family (Aspenström et al., 2006). Interestingly, DAAM1 localizes to the acto-myosin fibers in the centrosomal area, and participates in centrosome reorientation during the acquisition of the migratory polarity (Ang et al., 2010). "
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    ABSTRACT: The acquisition of a migratory phenotype is central in processes as diverse as embryo differentiation and tumor metastasis. An early event in this phenomenon is the generation of a nucleus-centrosome-Golgi back to front axis. AKAP350 is a Golgi/centrosome scaffold protein involved in microtubule nucleation. AKAP350 interacts with CIP4, a cdc42 effector that regulates actin dynamics. The present study aimed to characterize the participation of centrosomal AKAP350 in the acquisition of migratory polarity, and the involvement of CIP4 in the pathway. The decrease in total or in centrosomal AKAP350 led to decreased formation of the nucleus-centrosome-Golgi axis and defective cell migration. CIP4 localized at the centrosome. That was enhanced in migratory cells, but inhibited in cells with decreased centrosomal AKAP350. The interference with CIP4 expression or with CIP4/AKAP350 interaction also led to defective cell polarization. Centrosome positioning, but not nuclear movement was affected by loss of CIP4 or AKAP350 function. Our results support a model where AKAP350 recruits CIP4 to the centrosome, providing a centrosomal scaffold to integrate microtubule and actin dynamics, thus enabling centrosome polarization, and ensuring cell migration directionality. © 2015. Published by The Company of Biologists Ltd.
    Journal of Cell Science 07/2015; 128(17). DOI:10.1242/jcs.170878 · 5.43 Impact Factor
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    • "Proteins containing the conserved F-BAR domain, an extended version of the membrane-binding BAR domain (Heath and Insall, 2008; Roberts-Galbraith and Gould, 2010) may also contribute to interaction-mediated membrane localization of formins (albeit also here the localization may work in both directions, as F-BAR proteins are involved in large multiprotein complexes including RHO GTPases as well). Yeast and mammalian formin interactors such as FBP1/FBP17/Rapostlin (Wakita et al., 2011), FNBP1L/Toca (Huett et al., 2009) or CIP4 (Aspenström et al., 2006) all share a common architecture with an N-terminal F-BAR domain and C-terminal SH3 domain, with a coiled coil motif in between (Roberts-Galbraith and Gould, 2010). A mammalian homolog of CIP4, a prototype protein of this family originally identified as a Cdc42 (RHO GTPase) effector, interacts with the DAAM1 formin via its SH3 domain, raising thus the possibility that other SH3-containing proteins may bind formins as well (Aspenström et al., 2006). "
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    ABSTRACT: Formins are evolutionarily conserved eukaryotic proteins participating in actin and microtubule organization. Land plants have three formin clades, with only two - Class I and II - present in angiosperms. Class I formins are often transmembrane proteins, residing at the plasmalemma and anchoring the cortical cytoskeleton across the membrane to the cell wall, while Class II formins possess a PTEN-related membrane-binding domain. Lower plant Class III and non-plant formins usually contain domains predicted to bind RHO GTPases that are membrane-associated. Thus, some kind of membrane anchorage appears to be a common formin feature. Direct interactions between various non-plant formins and integral or peripheral membrane proteins have indeed been reported, with varying mechanisms and biological implications. Besides of summarizing new data on Class I and Class II formin-membrane relationships, this review surveys such "non-classical" formin-membrane interactions and examines which, if any, of them may be evolutionarily conserved and operating also in plants. FYVE, SH3 and BAR domain-containing proteins emerge as possible candidates for such conserved membrane-associated formin partners.
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    • "F-BAR proteins are involved in coupling actin dynamics with the membrane (Heath and Insall, 2008; Robertson et al., 2009; Aspenström, 2010; Fricke et al., 2010). Interestingly, members of the Cip4 subfamily of F-BAR proteins in mammals such as Cip4 and FBP17 have been originally identified as Formin-binding proteins (Chan et al., 1996; Aspenström et al., 2006). We have recently found that Cip4, the only member of the Cip4 subfamily in Drosophila, integrates membrane and actin dynamics through WASP and SCAR/WAVE proteins (Fricke et al., 2009). "
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