Crawling from soft to stiff matrix polarizes the cytoskeleton and phosphoregulates myosin-II heavy chain

Raab, Matthew; Swift, Joe; Dingal, P.C. Dave P.; Shah, Palak; Shin, Jae Won; Discher, Dennis E.

doi:10.1083/jcb.201205056

Cited by 259 publications

(334 citation statements)

References 42 publications

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“…1/K, the overall free energy, U, decreases with post stiffness, K p (equation (3.4) and figure 3d ). These predictions agree with the observations that cells prefer to migrate towards stiffer regions on a substrate with a stiffness gradient, which is known as durotaxis [28][29][30]: …”

Section: Cells Tend To Migrate Toward Stiffer Surroundingssupporting

confidence: 82%

A chemo-mechanical free-energy-based approach to model durotaxis and extracellular stiffness-dependent contraction and polarization of cells

Shenoy¹,

Wang²,

Xiao³

2016

Interface Focus.

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We propose a chemo-mechanical model based on stress-dependent recruitment of myosin motors to describe how the contractility, polarization and strain in cells vary with the stiffness of their surroundings and their shape. A contractility tensor, which depends on the distribution of myosin motors, is introduced to describe the chemical free energy of the cell due to myosin recruitment. We explicitly include the contributions to the free energy that arise from mechanosensitive signalling pathways (such as the SFX, Rho-Rock and MLCK pathways) through chemo-mechanical coupling parameters. Taking the variations of the total free energy, which consists of the chemical and mechanical components, in accordance with the second law of thermodynamics provides equations for the temporal evolution of the active stress and the contractility tensor. Following this approach, we are able to recover the well-known Hill relation for active stresses, based on the fundamental principles of irreversible thermodynamics rather than phenomenology. We have numerically implemented our free energy-based approach to model spatial distribution of strain and contractility in (i) cells supported by flexible microposts, (ii) cells on two-dimensional substrates, and (iii) cells in three-dimensional matrices. We demonstrate how the polarization of the cells and the orientation of stress fibres can be deduced from the eigenvalues and eigenvectors of the contractility tensor. Our calculations suggest that the chemical free energy of the cell decreases with the stiffness of the extracellular environment as the cytoskeleton polarizes in response to stress-dependent recruitment of molecular motors. The mechanical energy, which includes the strain energy and motor potential energy, however, increases with stiffness, but the overall energy is lower for cells in stiffer environments. This provides a thermodynamic basis for durotaxis, whereby cells preferentially migrate towards stiffer regions of the extracellular environment. Our models also explain, from an energetic perspective, why the shape of the cells can change in response to stiffness of the surroundings. The effect of the stiffness of the nucleus on its shape and the orientation of the stress fibres is also studied for all the above geometries. Along with making testable predictions, we have estimated the magnitudes of the chemo-mechanical coupling parameters for myofibroblasts based on data reported in the literature.

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Section: Cells Tend To Migrate Toward Stiffer Surroundingssupporting

confidence: 82%

A chemo-mechanical free-energy-based approach to model durotaxis and extracellular stiffness-dependent contraction and polarization of cells

Shenoy¹,

Wang²,

Xiao³

2016

Interface Focus.

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“…Moreover, S1943A and ΔNHT mutants of NMIIA overassemble with altered intracellular localization when expressed in HeLa cells (29), and phosphomimics at phosphoserine sites regulated the assembly and location of NMII rods expressed in mouse embryonic fibroblasts (26), although these mutations did not affect the paracrystal structure of the rods in vitro. Quite recently, it was observed that NMIIA is diffuse and mobile in mesenchymal stem cells crawling on a soft matrix but strongly assembled in oriented stress fibers in cells crawling on a stiff matrix (31). The shift from diffuse to assembled NMIIA correlated with, and apparently was caused by, a decrease in phosphorylation of S1943.…”

Section: Discussionmentioning

confidence: 97%

Regulation of the filament structure and assembly ofAcanthamoebamyosin II by phosphorylation of serines in the heavy-chain nonhelical tailpiece

Liu

Hong

Shu

et al. 2012

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

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Acanthamoeba myosin II (AMII) has two heavy chains ending in a 27-residue nonhelical tailpiece and two pairs of light chains. In a companion article, we show that five, and only five, serine residues can be phosphorylated both in vitro and in vivo: Ser639 in surface loop 2 of the motor domain and serines 1489, 1494, 1499, and 1504 in the nonhelical tailpiece of the heavy chains. In that paper, we show that phosphorylation of Ser639 down-regulates the actin-activated MgATPase activity of AMII and that phosphorylation of the serines in the nonhelical tailpiece has no effect on enzymatic activity. Here we show that bipolar tetrameric, hexameric, and octameric minifilaments of AMII with the nonhelical tailpiece serines either phosphorylated or mutated to glutamate have longer bare zones and more tightly clustered heads than minifilaments of unphosphorylated AMII, irrespective of the phosphorylation state of Ser639. Although antiparallel dimers of phosphorylated and unphosphorylated myosins are indistinguishable, phosphorylation inhibits dimerization and filament assembly. Therefore, the different structures of tetramers, hexamers, and octamers of phosphorylated and unphosphorylated AMII must be caused by differences in the longitudinal stagger of phosphorylated and unphosphorylated bipolar dimers and tetramers. Thus, although the actin-activated MgATPase activity of AMII is regulated by phosphorylation of Ser639 in loop 2 of the motor domain, the structure of AMII minifilaments is regulated by phosphorylation of one or more of four serines in the nonhelical tailpiece of the heavy chain.A s summarized in the accompanying paper (1), Acanthamoeba myosin II (AMII) is a typical class II myosin with two heavy chains and two pairs of light chains (2, 3). The coiled-coil helical tails of the heavy chains terminate with a 27-residue nonhelical tailpiece, 1483PSSRGGSTRGASARGASVRAGSARAEE1509, which has a pattern of four contiguous repeats of XXSXR (4). Previous work had shown that phosphorylation of two or more of these serines (residues 1489, 1494, 1499, and 1504) correlates with, and was assumed to be responsible for, inactivation of AMII's actin-activated MgATPase activity (5, 6). Also, it had been concluded that only filamentous AMII has actin-activated MgATPase activity (7, 8), and it was inferred that the ATPase activity is regulated by a change in the conformation of the bipolar minifilaments (9-11). However, detailed studies by the Pollard laboratory found no significant differences in either the polymerization properties or electron microscopic images of minifilaments of phosphorylated and dephosphorylated myosins (12-16).The earlier studies were carried out with purified endogenous myosin. To avoid possible complications in enzymatic and structural studies caused by the partial phosphorylation of purified endogenous myosin and incomplete dephosphorylation by phosphatase, we initiated studies on the enzymatic activity and structure of expressed recombinant wild-type, truncated, and mutant myosins before and after phos...

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“…This so-called durotaxis enables cells to migrate from soft to rigid matrix. In mesenchymal stem cells a polarization of the cytoskeleton facilitated by myosin-II heavy chain is responsible for this mechanosensitive migration [48].…”

Section: Cells and Mechanotransductionmentioning

confidence: 99%

Cell-material interaction

Rychly

Nebe

2013

BioNanoMaterials

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Abstract:The interaction of cells with material surfaces is of fundamental relevance and contributes to the clinical success of implants. Cells sense their physico-chemical environment resulting in focal adhesion reorganization, spatio-temporal localization and activation of integrin dependent signalling proteins as well as phenotypic changes, e.g., of the actin cytoskeleton. The technology of designing instructive biomaterials involves chemical modifications by grafting of chemical groups, adhesion ligands and growth factors. Physical modifications of the materials are created by structuring the surfaces stochastically and geometrically and by modifications of the material stiffness. Insights into the mechanism at the interface that are involved in the regulation of cells such as stem cells, osteoblasts and chondrocytes by materials will advance the development of innovative biomaterials in regenerative medicine.

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Crawling from soft to stiff matrix polarizes the cytoskeleton and phosphoregulates myosin-II heavy chain

Abstract: Cytoskeletal polarization occurs in response to mechanosensing of a transition from soft to stiff matrix during migration and promotes dephosphorylation of myosin-IIA, rearward localization of myosin-IIB, and durotaxis.

Cited by 259 publications

References 42 publications

A chemo-mechanical free-energy-based approach to model durotaxis and extracellular stiffness-dependent contraction and polarization of cells

A chemo-mechanical free-energy-based approach to model durotaxis and extracellular stiffness-dependent contraction and polarization of cells

Regulation of the filament structure and assembly ofAcanthamoebamyosin II by phosphorylation of serines in the heavy-chain nonhelical tailpiece

Cell-material interaction

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