Role of Formins in Actin Assembly: Nucleation and Barbed-End Association

Pruyne, David; Evangelista, Marie; Yang, Chao; Bi, Erfei; Zigmond, Sally H.; Bretscher, Anthony; Boone, Charles

doi:10.1126/science.1072309

Cited by 673 publications

(577 citation statements)

References 30 publications

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“…Formins induce the polymerization of long, parallel actin filament bundles found in filopodia (46,47) that are similar to the dynamic plasma membrane protrusions observed in cells adhered to a 30-kPa Ecad-Fc PA gel (Fig. 2A).…”

Section: Resultsmentioning

confidence: 78%

Changes in E-cadherin rigidity sensing regulate cell adhesion

Collins

Denisin

Pruitt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Mechanical cues are sensed and transduced by cell adhesion complexes to regulate diverse cell behaviors. Extracellular matrix (ECM) rigidity sensing by integrin adhesions has been well studied, but rigidity sensing by cadherins during cell adhesion is largely unexplored. Using mechanically tunable polyacrylamide (PA) gels functionalized with the extracellular domain of E-cadherin (Ecad-Fc), we showed that E-cadherin-dependent epithelial cell adhesion was sensitive to changes in PA gel elastic modulus that produced striking differences in cell morphology, actin organization, and membrane dynamics. Traction force microscopy (TFM) revealed that cells produced the greatest tractions at the cell periphery, where distinct types of actin-based membrane protrusions formed. Cells responded to substrate rigidity by reorganizing the distribution and size of hightraction-stress regions at the cell periphery. Differences in adhesion and protrusion dynamics were mediated by balancing the activities of specific signaling molecules. Cell adhesion to a 30-kPa Ecad-Fc PA gel required Cdc42-and formin-dependent filopodia formation, whereas adhesion to a 60-kPa Ecad-Fc PA gel induced Arp2/3-dependent lamellipodial protrusions. A quantitative 3D cell-cell adhesion assay and live cell imaging of cell-cell contact formation revealed that inhibition of Cdc42, formin, and Arp2/3 activities blocked the initiation, but not the maintenance of established cell-cell adhesions. These results indicate that the same signaling molecules activated by E-cadherin rigidity sensing on PA gels contribute to actin organization and membrane dynamics during cell-cell adhesion. We hypothesize that a transition in the stiffness of E-cadherin homotypic interactions regulates actin and membrane dynamics during initial stages of cellcell adhesion.C ell adhesion is essential for tissue structure and function. Cells use specialized types of adhesions to interact with the surrounding environment, including integrin-based focal adhesions at cell-extracellular matrix (cell-ECM) contacts and cadherin-based adhesions at cell-cell contacts (1). Integrins bind to the ECM and intracellular proteins that link to the actin cytoskeleton and important signaling pathways (2). Similarly, cadherins regulate cellcell recognition and adhesion (3) and, through cytoplasmic adaptor proteins (catenins, vinculin) (4, 5), also link to the actin cytoskeleton and other proteins with signaling and scaffolding functions (6).Initiation of cell-cell adhesion requires significant reorganization of the actin cytoskeleton and is tightly controlled by the activities of actin nucleating proteins and Rho GTPases. Adhesion is initiated when filopodia from opposing cells come into contact with one another (7,8), and this process is regulated by Cdc42 activity (9, 10) and formin-dependent actin polymerization (11)(12)(13)(14). Intermediate stages of cell-cell contact formation involve lateral expansion of the contact by Rac1-induced and Arp2/3-dependent lamellipodial activity (15, 16). Finally, com...

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Section: Resultsmentioning

confidence: 78%

Changes in E-cadherin rigidity sensing regulate cell adhesion

Collins

Denisin

Pruitt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…The first mechanism is mediated by the Arp2/3 complex (Goley and Welch, 2006;Mullins and Pollard, 1999;Welch et al, 1997;Welch and Mullins, 2002) that interacts with the surface of the existing actin filaments to create sites of branching for new actin polymerization and ensure actin assembly into the dendritic network that drives the protrusion of lamellipodia. The second mechanism is mediated by formins (Goode and Eck, 2007;Pruyne et al, 2002;Zigmond, 2004;Zigmond et al, 1998) that drive actin assembly into parallel cross-linked bundles that serve as a structural basis for filopodia.…”

Section: Basic Principles Of Cell Migration Overall Structure Of the mentioning

confidence: 99%

Cell biology of embryonic migration

Kurosaka¹,

Kashina²

2008

Birth Defects Research Pt C

117

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Cell migration is an evolutionarily conserved mechanism that underlies the development and functioning of uni-and multicellular organisms and takes place in normal and pathogenic processes, including various events of embryogenesis, wound healing, immune response, cancer metastases, and angiogenesis. Despite the differences in the cell types that take part in different migratory events, it is believed that all of these migrations occur by similar molecular mechanisms, whose major components have been functionally conserved in evolution and whose perturbation leads to severe developmental defects. These mechanisms involve intricate cytoskeleton-based molecular machines that can sense the environment, respond to signals, and modulate the entire cell behavior. A big question that has concerned the researchers for decades relates to the coordination of cell migration in situ and its relation to the intracellular aspects of the cell migratory mechanisms. Traditionally, this question has been addressed by researchers that considered the intra-and extracellular mechanisms driving migration in separate sets of studies. As more data accumulate researchers are now able to integrate all of the available information and consider the intracellular mechanisms of cell migration in the context of the developing organisms that contain additional levels of complexity provided by extracellular regulation. This review provides a broad summary of the existing and emerging data in the cell and developmental biology fields regarding cell migration during development.

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“…At higher salt concentrations the formin binding to the filament ends is weaker and thus the development of its conformational effect in actin requires more formin. At greater formin concentrations the low affinity binding sites (K D = 3 μM [39]) on the sides of the actin filaments becomes more saturated. The formins attached to the sides of the filaments stabilise the interaction between the neighbouring actin protomers and thus stabilise the structure of the actin filaments too [17,18].…”

Section: Discussionmentioning

confidence: 99%

The effects of formins on the conformation of subdomain 1 in actin filaments

Ujfalusi

Barkó

Hild

et al. 2010

Journal of Photochemistry and Photobiology B: Biology

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In this study we investigated the effects of formins on the conformation of actin filaments by using the method of fluorescence quenching. Actin was labelled with IAEDANS at Cys 374 and the quencher was acrylamide. The results showed that formin binding induced structural changes in the subdomain 1 of actin protomers which were reflected by greater quenching constants (K SV ). Simultaneously the fraction of the fluorophore population accessible for the quencher (α) decreased. These observations suggest that the conformational distribution characteristic for the actin protomers became broader after the binding of formins, for which the structural framework was provided by a more flexible protein matrix in the microenvironment of the label. The effects of formins depended on the formin:actin molar ratio, and also on the ionic strength of the medium. These observations are in agreement with previous results and underline the importance of the intramolecular conformational changes induced by formins in the structure of actin filaments.

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Role of Formins in Actin Assembly: Nucleation and Barbed-End Association

Cited by 673 publications

References 30 publications

Changes in E-cadherin rigidity sensing regulate cell adhesion

Changes in E-cadherin rigidity sensing regulate cell adhesion

Cell biology of embryonic migration

The effects of formins on the conformation of subdomain 1 in actin filaments

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