Stressing the limits of focal adhesion mechanosensitivity

Oakes, Patrick W.; Gardel, Margaret L.

doi:10.1016/j.ceb.2014.06.003

Cited by 124 publications

(116 citation statements)

References 72 publications

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“…This is mediated by an increase in integrin clustering and in the size and number of integrin-based focal adhesions (Califano and Reinhart-King, 2010;van Geemen et al, 2014). Integrins sense the stiffness of the underlying substrate and translate mechanical forces into endothelial signaling to induce F-actin remodeling and myosin-based contraction (Oakes and Gardel, 2014;Roca-Cusachs et al, 2012;Ross et al, 2013). Human ECs on stiff matrices show increased numbers of focal adhesions and F-actin stress fibers, similar to what was observed in rigid human arteries (van Geemen et al, 2014).…”

Section: Mechanotransduction In Ecs Substrate Stiffness Controls Endomentioning

confidence: 87%

Cell-stiffness-induced mechanosignaling – a key driver of leukocyte transendothelial migration

Schaefer

Hordijk

2015

Journal of Cell Science

103

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The breaching of cellular and structural barriers by migrating cells is a driving factor in development, inflammation and tumor cell metastasis. One of the most extensively studied examples is the extravasation of activated leukocytes across the vascular endothelium, the inner lining of blood vessels. Each step of this leukocyte transendothelial migration (TEM) process is regulated by distinct endothelial adhesion receptors such as the intercellular adhesion molecule 1 (ICAM1). Adherent leukocytes exert force on these receptors, which sense mechanical cues and transform them into localized mechanosignaling in endothelial cells. In turn, the function of the mechanoreceptors is controlled by the stiffness of the endothelial cells and of the underlying substrate representing a positive-feedback loop. In this Commentary, we focus on the mechanotransduction in leukocytes and endothelial cells, which is induced in response to variations in substrate stiffness. Recent studies have described the first key proteins involved in these mechanosensitive events, allowing us to identify common regulatory mechanisms in both cell types. Finally, we discuss how endothelial cell stiffness controls the individual steps in the leukocyte TEM process. We identify endothelial cell stiffness as an important component, in addition to locally presented chemokines and adhesion receptors, which guides leukocytes to sites that permit TEM.

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Section: Mechanotransduction In Ecs Substrate Stiffness Controls Endomentioning

confidence: 87%

Cell-stiffness-induced mechanosignaling – a key driver of leukocyte transendothelial migration

Schaefer

Hordijk

2015

Journal of Cell Science

103

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“…Collectively, the integration of such counterforces across numerous integrin-talin-actin modules in a given FA may then give rise to a membrane-parallel cortical tension. That is, the stress fiber may exert force on both the FA and the surrounding cortical cytoskeleton-the latter could be considered analogous to friction, a common parameter in biophysical models of FAs (14,49).…”

Section: Discussionmentioning

confidence: 99%

Talin determines the nanoscale architecture of focal adhesions

Liu

Wang

Goh

et al. 2015

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

180

169

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Insight into how molecular machines perform their biological functions depends on knowledge of the spatial organization of the components, their connectivity, geometry, and organizational hierarchy. However, these parameters are difficult to determine in multicomponent assemblies such as integrin-based focal adhesions (FAs). We have previously applied 3D superresolution fluorescence microscopy to probe the spatial organization of major FA components, observing a nanoscale stratification of proteins between integrins and the actin cytoskeleton. Here we combine superresolution imaging techniques with a protein engineering approach to investigate how such nanoscale architecture arises. We demonstrate that talin plays a key structural role in regulating the nanoscale architecture of FAs, akin to a molecular ruler. Talin diagonally spans the FA core, with its N terminus at the membrane and C terminus demarcating the FA/stress fiber interface. In contrast, vinculin is found to be dispensable for specification of FA nanoscale architecture. Recombinant analogs of talin with modified lengths recapitulated its polarized orientation but altered the FA/stress fiber interface in a linear manner, consistent with its modular structure, and implicating the integrin-talin-actin complex as the primary mechanical linkage in FAs. Talin was found to be ∼97 nm in length and oriented at ∼15°relative to the plasma membrane. Our results identify talin as the primary determinant of FA nanoscale organization and suggest how multiple cellular forces may be integrated at adhesion sites.superresolution microscopy | focal adhesions | talin | mechanobiology | nanoscale architecture C ell adhesion to the ECM is a highly coordinated process that involves ECM-specific recognition by integrin transmembrane receptors, and their aggregation with numerous cytoplasmic proteins into dense supramolecular complexes called focal adhesions (FAs) (1). Actin stress fibers terminate at FAs where actomyosin contractility is transmitted to the ECM, generating traction (2-5). Mechanical tension impinging on each FA is implicated in key steps including the elongation, reinforcement, and maintenance of the FA structures (6). FA mechanotransduction is a major aspect of cellular microenvironment sensing with wide-ranging consequences in physiological and pathological processes (7-10). However, molecular-scale spatial parameters that specify FA nanoscale organization have been difficult to access experimentally. Nevertheless, these are essential to understand how mechanosensitivity arises within such complex molecular machines (11-15).Previously 3D superresolution fluorescence microscopy has unveiled the nanoscale organization of major FA components, whereby a core region of ∼30 nm interposes between the integrin and the actin cytoskeleton along the vertical (z) axis (16). The FA core consists of a membrane-proximal layer that contains signaling proteins such as FAK (focal adhesion kinase) and paxillin, an intermediate zone that contains force-transduction proteins s...

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“…The generation of traction forces by cells is essential for motility and requires cytoskeleton coupling to matrix adhesion sites (Oakes and Gardel, 2014). The impact of β-PIX KD on FAs, cytoskeleton organization and MLC activation led us to investigate whether these changes result in modulation of the traction forces exerted by cells on their substrate.…”

Section: Traction Force Magnitude Is Increased In β-Pix Kd Hacat Cellsmentioning

confidence: 99%

“…During development and wound healing of epithelial tissues, cell-matrix adhesions and the cytoskeleton cooperatively function to regulate the traction forces of the cells on their substrate (Oakes and Gardel, 2014). These traction forces are needed for individual as well as groups of cells to migrate over the wound bed.…”

Section: Introductionmentioning

confidence: 99%

Loss of β-PIX inhibits focal adhesion disassembly and promotes keratinocyte motility via myosin light chain activation

Hiroyasu

Stimac

Hopkinson

et al. 2017

Journal of Cell Science

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During healing of the skin, the cytoskeleton of keratinocytes and their matrix adhesions, including focal adhesions (FAs), undergo reorganization. These changes are coordinated by small GTPases and their regulators, including the guanine nucleotide exchange factor β-PIX (also known as ARHGEF7). In fibroblasts, β-PIX activates small GTPases, thereby enhancing migration. In keratinocytes in vitro, β-PIX localizes to FAs. To study β-PIX functions, we generated β-PIX knockdown keratinocytes. During wound closure of β-PIX knockdown cell monolayers, disassembly of FAs is impaired, and their number and size are increased. In addition, in the β-PIX knockdown cells, phosphorylated myosin light chain (MLC; also known as MYL2) is present not only in the leading edge of cells at the wound front, but also in the cells following the front, while p21-activated kinase 2 (PAK2), a regulator of MLC kinase (MYLK), is mislocalized. Inhibition or depletion of MYLK restores FA distribution in β-PIX knockdown cells. Traction forces generated by β-PIX knockdown cells are increased relative to those in control cells, a result consistent with an unexpected enhancement in the migration of single β-PIX knockdown cells and monolayers of such cells. We propose that targeting β-PIX might be a means of promoting epithelialization of wounds in vivo.

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Stressing the limits of focal adhesion mechanosensitivity

Cited by 124 publications

References 72 publications

Cell-stiffness-induced mechanosignaling – a key driver of leukocyte transendothelial migration

Cell-stiffness-induced mechanosignaling – a key driver of leukocyte transendothelial migration

Talin determines the nanoscale architecture of focal adhesions

Loss of β-PIX inhibits focal adhesion disassembly and promotes keratinocyte motility via myosin light chain activation

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