Mechanosensitive myosin II but not cofilin primarily contributes to cyclic cell stretch-induced selective disassembly of actin stress fibers

2021 ◽  
Author(s):  
Wenjing Huang ◽  
Tsubasa S. Matsui ◽  
Takumi Saito ◽  
Masahiro Kuragano ◽  
Masayuki Takahashi ◽  
...  
Keyword(s):  
Cellular Response ◽  
Early Stage ◽  
Myosin Ii ◽  
Cyclic Stretch ◽  
Stress Fibers ◽  
Lim Kinase ◽  
Lim Kinase 1 ◽  
Chronic Activation ◽  
Selective Disassembly ◽  
Actin Stress Fibers

Cells adapt to applied cyclic stretch (CS) to circumvent chronic activation of proinflammatory signaling. Currently, the molecular mechanism of the selective disassembly of actin stress fibers (SFs) in the stretch direction, which occurs at the early stage of the cellular response to CS, remains controversial. Here we suggest that the mechanosensitive behavior of myosin II, a major cross-linker of SFs, primarily contributes to the directional disassembly of the actomyosin complex SFs in bovine vascular smooth muscle cells and human U2OS osteosarcoma cells. First, we identified that CS with a shortening phase that exceeds in speed the inherent contractile rate of individual SFs leads to the disassembly. To understand the biological basis, we investigated the effect of expressing myosin regulatory light chain mutants and found that SFs with less actomyosin activities disassemble more promptly upon CS. We consequently created a minimal mathematical model that recapitulates the salient features of the direction-selective and threshold-triggered disassembly of SFs to show that disassembly or, more specifically, unbundling of the actomyosin bundle SFs is enhanced with sufficiently fast cell shortening. We further demonstrated that similar disassembly of SFs is inducible in the presence of an active LIM-kinase-1 mutant that deactivates cofilin, suggesting that cofilin is dispensable as opposed to a previously proposed mechanism.

Mechanically Optimized Orientation of Intracellular Stress Fibers Under Cyclic Stretch

2000 ◽  
Author(s):  
Hiroshi Yamada ◽  
Tohru Takemasa ◽  
Takami Yamaguchi
Keyword(s):  
Endothelial Cell ◽  
Continuum Mechanics ◽  
Cellular Response ◽  
Length Change ◽  
Mechanical Stimulus ◽  
Stress Fiber ◽  
Cyclic Stretch ◽  
Stress Fibers ◽  
Biological Phenomenon ◽  
The Continuum

Abstract To elucidate the orientation of stress fibers in a cultured endothelial cell under cyclic stretch, we hypothesized that a stress fiber aligns so as to minimize the summation of its length change under cyclic stretch, and that there is a limit in the sensitivity of cellular response to the mechanical stimulus. Results from numerical simulations based on the continuum mechanics describe the experimental observations under uniaxial stretch well. They give us an insight to the biological phenomenon of the orientation in stress fibers under biaxial stretch from the viewpoint of mechanical engineering.

Rho-kinase regulates myosin II activation in MDCK cells during recovery after ATP depletion

2001 ◽  
Vol 281 (5) ◽  
pp. F810-F818 ◽  
Author(s):  
Timothy A. Sutton ◽  
Henry E. Mang ◽  
Simon J. Atkinson
Keyword(s):  
Epithelial Cells ◽  
Actin Cytoskeleton ◽  
Mdck Cells ◽  
Myosin Ii ◽  
Atp Depletion ◽  
Stress Fibers ◽  
Tubular Epithelial Cells ◽  
Renal Tubular Epithelial Cells ◽  
Renal Tubular ◽  
Actin Stress Fibers

Alterations in the actin cytoskeleton of renal tubular epithelial cells during periods of ischemic injury and recovery have important consequences for normal cell and kidney function. Myosin II has been demonstrated to be an important effector in organizing basal actin structures in some cell types. ATP depletion in vitro has been demonstrated to recapitulate alterations of the actin cytoskeleton in renal tubular epithelial cells observed during renal ischemia in vivo. We utilized this reversible cell culture model of ischemia to examine the correlation of the activation state and cellular distribution of myosin II with disruption of actin stress fibers in Madin-Darby canine kidney (MDCK) cells during ATP depletion and recovery from ATP depletion. We found that myosin II inactivation occurs rapidly and precedes dissociation of myosin II from actin stress fibers during ATP depletion. Myosin II activation temporally correlates with colocalization of myosin II to reorganizing stress fibers during recovery from ATP depletion. Furthermore, myosin activation and actin stress fiber formation were found to be Rho-associated Ser/Thr protein kinase dependent during recovery from ATP depletion.

Active FHOD1 promotes the formation of functional actin stress fibers

2019 ◽  
Vol 476 (20) ◽  
pp. 2953-2963 ◽  
Author(s):  
Xuemeng Shi ◽  
Shuangshuang Zhao ◽  
Jinping Cai ◽  
Gary Wong ◽  
Yaming Jiu
Keyword(s):  
Myosin Ii ◽  
Critical Role ◽  
Active Form ◽  
Focal Adhesions ◽  
Stress Fibers ◽  
Cell Periphery ◽  
Physiological Relevance ◽  
Human Osteosarcoma Cells ◽  
And Migration ◽  
Actin Stress Fibers

Abstract The formin FHOD1 acts as a nucleating, capping and bundling protein of actin filaments. In cells, release from the C-terminal diaphanous autoregulatory domain (DAD) of FHOD1 stimulates the protein into the active form. However, the cellular physiological relevance of active form FHOD1 and the phenotypic regulation by FHOD1 depletion are not completely understood. Here, we show that in contrast with the cytosolic diffused expression of auto-inhibited FHOD1, active FHOD1 by C-terminal truncation was recruited into all three types of actin stress fibers in human osteosarcoma cells. Notably, the recruited active FHOD1 was more incorporated with myosin II than α-actinin, and associated with both naïve and mature focal adhesions. Active FHOD1 displayed faster turnover than actin molecules on ventral stress fibers. Moreover, we witnessed the emergence of active FHOD1 from the cell periphery, which subsequently moved centripetally together with transverse arcs. Furthermore, FHOD1 knockdown resulted in defective maturation of actomyosin bundles and subsequently longer non-contractile dorsal stress fibers, whereas the turnover of both actin and myosin II were maintained normally. Importantly, the loss of FHOD1 led to slower actin centripetal flow, resulting in abnormal cell spreading and migration defects. Taken together, these results reveal a critical role of FHOD1 in temporal- and spatial- control of the morphology and dynamics of functional actin stress fibers during variable cell behavior.

scholarly journals Mechanical force mobilizes zyxin from focal adhesions to actin filaments and regulates cytoskeletal reinforcement

2005 ◽  
Vol 171 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Masaaki Yoshigi ◽  
Laura M. Hoffman ◽  
Christopher C. Jensen ◽  
H. Joseph Yost ◽  
Mary C. Beckerle
Keyword(s):  
Shear Stress ◽  
Mechanical Stress ◽  
Actin Filaments ◽  
Focal Adhesions ◽  
Cyclic Stretch ◽  
Stress Fibers ◽  
Focal Adhesion Proteins ◽  
Cytoskeletal Responses ◽  
Actin Stress Fibers

Organs and tissues adapt to acute or chronic mechanical stress by remodeling their actin cytoskeletons. Cells that are stimulated by cyclic stretch or shear stress in vitro undergo bimodal cytoskeletal responses that include rapid reinforcement and gradual reorientation of actin stress fibers; however, the mechanism by which cells respond to mechanical cues has been obscure. We report that the application of either unidirectional cyclic stretch or shear stress to cells results in robust mobilization of zyxin from focal adhesions to actin filaments, whereas many other focal adhesion proteins and zyxin family members remain at focal adhesions. Mechanical stress also induces the rapid zyxin-dependent mobilization of vasodilator-stimulated phosphoprotein from focal adhesions to actin filaments. Thickening of actin stress fibers reflects a cellular adaptation to mechanical stress; this cytoskeletal reinforcement coincides with zyxin mobilization and is abrogated in zyxin-null cells. Our findings identify zyxin as a mechanosensitive protein and provide mechanistic insight into how cells respond to mechanical cues.

Cofilin mediates ATP depletion-induced endothelial cell actin alterations

2006 ◽  
Vol 290 (6) ◽  
pp. F1398-F1407 ◽  
Author(s):  
Maria V. Suurna ◽  
Sharon L. Ashworth ◽  
Melanie Hosford ◽  
Ruben M. Sandoval ◽  
Sarah E. Wean ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Actin Cytoskeleton ◽  
Fluorescent Protein ◽  
Cell Damage ◽  
Fluorescent Imaging ◽  
Atp Depletion ◽  
Stress Fibers ◽  
Cortical Actin ◽  
Lim Kinase ◽  
Actin Stress Fibers

Ischemia and sepsis lead to endothelial cell damage, resulting in compromised microvascular flow in many organs. Much remains to be determined regarding the intracellular structural events that lead to endothelial cell dysfunction. To investigate potential actin cytoskeletal-related mechanisms, ATP depletion was induced in mouse pancreatic microvascular endothelial cells (MS1). Fluorescent imaging and biochemical studies demonstrated a rapid and progressive increase in F-actin along with a decrease in G-actin at 60 min. Confocal microscopic analysis showed ATP depletion resulted in destruction of actin stress fibers and accumulation of F-actin aggregates. We hypothesized these actin alterations were secondary to dephosphorylation/activation of actin-depolymerizing factor (ADF)/cofilin proteins. Cofilin, the predominant isoform expressed in MS1 cells, was rapidly dephosphorylated/activated during ATP depletion. To directly investigate the role of cofilin activation on the actin cytoskeleton during ischemia, MS1 cells were infected with adenoviruses containing the cDNAs for wild-type Xenopus laevis ADF/cofilin green fluorescent protein [XAC(wt)-GFP], GFP, and the constitutively active and inactive isoforms XAC(S3A)-GFP and XAC(S3E)-GFP. The rate and extent of cortical actin destruction and actin aggregate formation were increased in ATP-depleted XAC(wt)-GFP- and XAC(S3A)-GFP-expressing cells, whereas increased actin stress fibers were observed in XAC(S3E)-GFP-expressing cells. To investigate the upstream signaling pathway of ADF/cofilin, LIM kinase 1-GFP (LIMK1-GFP) was expressed in MS1 cells. Cells expressing LIMK1-GFP protein had higher levels of phosphorylated ADF/cofilin, increased stress fibers, and delayed F-actin cytoskeleton destruction during ATP depletion. These results strongly support the importance of cofilin regulation in ischemia-induced endothelial cell actin cytoskeleton alterations leading to cell damage and microvascular dysfunction.

scholarly journals Stretch-induced actin remodeling requires targeting of zyxin to stress fibers and recruitment of actin regulators

2012 ◽  
Vol 23 (10) ◽  
pp. 1846-1859 ◽  
Author(s):  
Laura M. Hoffman ◽  
Christopher C. Jensen ◽  
Aashi Chaturvedi ◽  
Masaaki Yoshigi ◽  
Mary C. Beckerle
Keyword(s):  
Mechanical Stimulation ◽  
Binding Capacity ◽  
Rho Kinase ◽  
Stress Fiber ◽  
Cyclic Stretch ◽  
Mitogen Activated Protein Kinase ◽  
Stress Fibers ◽  
Actin Remodeling ◽  
Mitogen Activated Protein ◽  
Actin Stress Fibers

Reinforcement of actin stress fibers in response to mechanical stimulation depends on a posttranslational mechanism that requires the LIM protein zyxin. The C-terminal LIM region of zyxin directs the force-sensitive accumulation of zyxin on actin stress fibers. The N-terminal region of zyxin promotes actin reinforcement even when Rho kinase is inhibited. The mechanosensitive integrin effector p130Cas binds zyxin but is not required for mitogen-activated protein kinase–dependent zyxin phosphorylation or stress fiber remodeling in cells exposed to uniaxial cyclic stretch. α-Actinin and Ena/VASP proteins bind to the stress fiber reinforcement domain of zyxin. Mutation of their docking sites reveals that zyxin is required for recruitment of both groups of proteins to regions of stress fiber remodeling. Zyxin-null cells reconstituted with zyxin variants that lack either α-actinin or Ena/VASP-binding capacity display compromised response to mechanical stimulation. Our findings define a bipartite mechanism for stretch-induced actin remodeling that involves mechanosensitive targeting of zyxin to actin stress fibers and localized recruitment of actin regulatory machinery.

scholarly journals B-Raf Acts via the ROCKII/LIMK/Cofilin Pathway To Maintain Actin Stress Fibers in Fibroblasts

2004 ◽  
Vol 24 (13) ◽  
pp. 5937-5952 ◽  
Author(s):  
Catrin A. Pritchard ◽  
Louise Hayes ◽  
Leszek Wojnowski ◽  
Andreas Zimmer ◽  
Richard M. Marais ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Myosin Light Chain ◽  
Fold Increase ◽  
Stress Fibers ◽  
Embryonic Fibroblasts ◽  
Lim Kinase ◽  
Catalytically Active ◽  
High Level ◽  
Actin Stress Fibers

ABSTRACT Recent data have shown that the BRAF gene is mutated at a high frequency in human malignancies. We have analyzed the migratory characteristics of B-raf−/− mouse embryonic fibroblasts (MEFs) and compared these with the organization of the actin cytoskeleton and the activity of signaling pathways that are known to influence this organization. Disruption of B-raf significantly reduced the levels of phospho-ERK1/2 and, surprisingly, induced an ≈1.5-fold increase in cell migration. Consistent with these findings, the high level of actin stress fibers normally present in MEFs was considerably reduced following disruption of B-raf, and the F-actin content of B-raf−/− cells was less than half that of B-raf+/+ cells. Phosphorylation of the myosin light chain on Thr18/Ser19 residues was not reduced in B-raf−/− cells. Rather, reduced ROCKII expression and attenuated phosphorylation of ADF/cofilin on serine 3 occurred. Normal stress fiber and phosphocofilin levels were restored by the expression of human B-Raf and catalytically active MEK and by the overexpression of LIM kinase (LIMK). These results have important implications for the role of the B-Raf/ERK signaling pathway in regulating cell motility in normal and malignant cells. They suggest that B-Raf is involved in invasiveness by regulating the proper assembly of actin stress fibers and contractility through a ROCKII/LIMK/cofilin signaling pathway.

scholarly journals Mechanoadaptive organization of stress fiber subtypes in epithelial cells under cyclic stretches and stretch release

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Amir Roshanzadeh ◽  
Tham Thi Nguyen ◽  
Khoa Dang Nguyen ◽  
Dong-Su Kim ◽  
Bong-Kee Lee ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
High Stability ◽  
Myosin Ii ◽  
Mechanical Stretch ◽  
Stress Fiber ◽  
Cyclic Stretch ◽  
Stress Fibers ◽  
Strain Magnitude ◽  
Additional Formation ◽  
Strain Dependent

Abstract Cyclic stretch applied to cells induces the reorganization of stress fibers. However, the correlation between the reorganization of stress fiber subtypes and strain-dependent responses of the cytoplasm and nucleus has remained unclear. Here, we investigated the dynamic involvement of stress fiber subtypes in the orientation and elongation of cyclically stretched epithelial cells. We applied uniaxial cyclic stretches at 5%, 10%, and 15% strains to cells followed by the release of the mechanical stretch. Dorsal, transverse arcs, and peripheral stress fibers were mainly involved in the cytoplasm responses whereas perinuclear cap fibers were associated with the reorientation and elongation of the nucleus. Dorsal stress fibers and transverse arcs rapidly responded within 15 min regardless of the strain magnitude to facilitate the subsequent changes in the orientation and elongation of the cytoplasm. The cyclic stretches induced the additional formation of perinuclear cap fibers and their increased number was almost maintained with a slight decline after 2-h-long stretch release. The slow formation and high stability of perinuclear cap fibers were linked to the slow reorientation kinetics and partial morphology recovery of nucleus in the presence or absence of cyclic stretches. The reorganization of stress fiber subtypes occurred in accordance with the reversible distribution of myosin II. These findings allowed us to propose a model for stretch-induced responses of the cytoplasm and nucleus in epithelial cells based on different mechanoadaptive properties of stress fiber subtypes.

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