The Roles of Caveolae and Caveolin in Cell Shape, Locomotion, and Stress Fiber Formation

2006 ◽  
pp. 195-204
Author(s):  
Sang Chul Park ◽  
Kyung A. Cho
Keyword(s):  
Cell Shape ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fiber Formation

scholarly journals ARHGAP18, a GTPase-activating protein for RhoA, controls cell shape, spreading, and motility

2011 ◽  
Vol 22 (20) ◽  
pp. 3840-3852 ◽  
Author(s):  
Masao Maeda ◽  
Hitoki Hasegawa ◽  
Toshinori Hyodo ◽  
Satoko Ito ◽  
Eri Asano ◽  
...  
Keyword(s):  
Rho Gtpases ◽  
Cell Shape ◽  
Cell Spreading ◽  
Bound State ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fiber Formation ◽  
Rna Transfection ◽  
And Migration

Rho GTPases are molecular switches that transmit biochemical signals in response to extracellular stimuli to elicit changes in the actin cytoskeleton. Rho GTPases cycle between an active, GTP-bound state and an inactive, GDP-bound state. These states are regulated by two distinct families of proteins—guanine nucleotide exchange factors and GTPase-activating proteins (GAPs). We studied the role of a previously uncharacterized GAP, ARHGAP18 (MacGAP). Overexpression of ARHGAP18 suppressed the activity of RhoA and disrupted stress fiber formation. Conversely, silencing of ARHGAP18 by small interfering RNA transfection–enhanced stress fiber formation and induced rounding of cells. We examined the role of ARHGAP18 in cell spreading and migration. Immunofluorescence analysis revealed that ARHGAP18 was localized to the leading edge during cell spreading and migration. ARHGAP18-knockdown cells showed impaired spreading, premature formation of stress fibers, and sustained activation of RhoA upon cell attachment. In addition, knockdown and overexpression of ARHGAP18 resulted in the inhibition and promotion of cell migration, respectively. Furthermore, ARHGAP18 was required for the polarization of cells for migration. Our results define ARHGAP18 as one of the crucial factors for the regulation of RhoA for the control of cell shape, spreading, and migration.

scholarly journals EpCAM promotes endosomal modulation of the cortical RhoA zone for epithelial organization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cécile Gaston ◽  
Simon De Beco ◽  
Bryant Doss ◽  
Meng Pan ◽  
Estelle Gauquelin ◽  
...  
Keyword(s):  
Cell Shape ◽  
Specific Protein ◽  
Cell Polarization ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Endosomal Trafficking ◽  
Transient Zone ◽  
And Behavior ◽  
Fine Tune

AbstractAt the basis of cell shape and behavior, the organization of actomyosin and its ability to generate forces are widely studied. However, the precise regulation of this contractile network in space and time is unclear. Here, we study the role of the epithelial-specific protein EpCAM, a contractility modulator, in cell shape and motility. We show that EpCAM is required for stress fiber generation and front-rear polarity acquisition at the single cell level. In fact, EpCAM participates in the remodeling of a transient zone of active RhoA at the cortex of spreading epithelial cells. EpCAM and RhoA route together through the Rab35/EHD1 fast recycling pathway. This endosomal pathway spatially organizes GTP-RhoA to fine tune the activity of actomyosin resulting in polarized cell shape and development of intracellular stiffness and traction forces. Impairment of GTP-RhoA endosomal trafficking either by silencing EpCAM or by expressing Rab35/EHD1 mutants prevents proper myosin-II activity, stress fiber formation and ultimately cell polarization. Collectively, this work shows that the coupling between co-trafficking of EpCAM and RhoA, and actomyosin rearrangement is pivotal for cell spreading, and advances our understanding of how biochemical and mechanical properties promote cell plasticity.

Regulation of Osteoblast-Like Cell Behaviors on Hydroxyapatite by Electrical Polarization

2007 ◽  
Vol 361-363 ◽  
pp. 1055-1058 ◽  
Author(s):  
Miho Nakamura ◽  
Akiko Nagai ◽  
Natalie Ohashi ◽  
Yumi Tanaka ◽  
Yasutaka Sekijima ◽  
...  
Keyword(s):  
Cell Movement ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Wound Healing Assay ◽  
Cell Behaviors ◽  
Stress Fiber Formation ◽  
Cytoskeleton Reorganization ◽  
Osteoblast Adhesion ◽  
As Stress

The osteoblast adhesion to the substrates are recognized to play a fundamental role in osteoconduction process. The purpose of this study was to evaluate the in vitro behavior of osteoblasts cultured on polarized hydroxyapatite (HA), having the enhanced osteobonding abilities. Osteoblast-like cells were seeded onto the polarized HA and investigated the adhesion and motility. The polarization had no effects on the percentage of the number of the spreaded cells against all the adhered cells, but had significant effects on the elongation of adhered cells from fluorescent observation and on the cell motility showed by the wound healing assay. The charges induced on the HA surface accelerated the cytoskeleton reorganization of the adhered cells cultured on HA specimens. The acceleration was emerged as the cells shape, actin filament pattern such as stress fiber formation, and the prolongation of the cell movement distances.

scholarly journals Novel Roles for α3β1 Integrin as a Regulator of Cytoskeletal Assembly and as a Trans-dominant Inhibitor of Integrin Receptor Function in Mouse Keratinocytes

1998 ◽  
Vol 142 (5) ◽  
pp. 1357-1369 ◽  
Author(s):  
Kairbaan M. Hodivala-Dilke ◽  
C. Michael DiPersio ◽  
Jordan A. Kreidberg ◽  
Richard O. Hynes
Keyword(s):  
Stress Fiber ◽  
Fiber Formation ◽  
The Other ◽  
Collagen Type Iv ◽  
Focal Contact ◽  
Actin Organization ◽  
Α3β1 Integrin ◽  
Stress Fiber Formation ◽  
Associated Proteins ◽  
Mouse Keratinocytes

Previously we found that α3β1 integrin–deficient neonatal mice develop micro-blisters at the epidermal–dermal junction. These micro-blisters were associated with poor basement membrane organization. In the present study we have investigated the effect of α3β1-deficiency on other keratinocyte integrins, actin-associated proteins and F-actin organization. We show that the absence of α3β1 results in an increase in stress fiber formation in keratinocytes grown in culture and at the basal face of the basal keratinocytes of α3-null epidermis. Moreover, we see a higher concentration of actin-associated proteins such as vinculin, talin, and α-actinin at focal contact sites in the α3-deficient keratinocytes. These changes in focal contact composition were not due to a change in steady-state levels of these proteins, but rather to reorganization due to α3β1 deficiency. Apart from the loss of α3β1 there is no change in expression of the other integrins expressed by the α3-null keratinocytes. However, in functional assays, α3β1 deficiency allows an increase in fibronectin and collagen type IV receptor activities. Thus, our findings provide evidence for a role of α3β1 in regulating stress fiber formation and as a trans-dominant inhibitor of the functions of the other integrins in mouse keratinocytes. These results have potential implications for the regulation of keratinocyte adhesion and migration during wound healing.

scholarly journals Delayed stress fiber formation mediates pulmonary myofibroblast differentiation in response to TGF-β

2011 ◽  
Vol 301 (5) ◽  
pp. L656-L666 ◽  
Author(s):  
Nathan Sandbo ◽  
Andrew Lau ◽  
Jacob Kach ◽  
Caitlyn Ngam ◽  
Douglas Yau ◽  
...  
Keyword(s):  
Rho Kinase ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Nuclear Accumulation ◽  
Myofibroblast Differentiation ◽  
Latrunculin B ◽  
Stress Fiber Formation ◽  
Actin Expression ◽  
Actin Stress Fibers

Myofibroblast differentiation induced by transforming growth factor-β (TGF-β) and characterized by de novo expression of smooth muscle (SM)-specific proteins is a key process in wound healing and in the pathogenesis of fibrosis. We have previously shown that TGF-β-induced expression and activation of serum response factor (SRF) is required for this process. In this study, we examined the signaling mechanism for SRF activation by TGF-β as it relates to pulmonary myofibroblast differentiation. TGF-β stimulated a profound, but delayed (18–24 h), activation of Rho kinase and formation of actin stress fibers, which paralleled SM α-actin expression. The translational inhibitor cycloheximide blocked these processes without affecting Smad-dependent gene transcription. Inhibition of Rho kinase by Y-27632 or depolymerization of actin by latrunculin B resulted in inhibition TGF-β-induced SRF activation and SM α-actin expression, having no effect on Smad signaling. Conversely, stabilization of actin stress fibers by jasplakinolide was sufficient to drive these processes in the absence of TGF-β. TGF-β promoted a delayed nuclear accumulation of the SRF coactivator megakaryoblastic leukemia-1 (MKL1)/myocardin-related transcription factor-A, which was inhibited by latrunculin B. Furthermore, TGF-β also induced MKL1 expression, which was inhibited by latrunculin B, by SRF inhibitor CCG-1423, or by SRF knockdown. Together, these data suggest a triphasic model for myofibroblast differentiation in response to TGF-β that involves 1) initial Smad-dependent expression of intermediate signaling molecules driving Rho activation and stress fiber formation, 2) nuclear accumulation of MKL1 and activation of SRF as a result of actin polymerization, and 3) SRF-dependent expression of MKL1, driving further myofibroblast differentiation.

Endothelial cytoskeletal reorganization in response to PAR1 stimulation is mediated by membrane rafts but not caveolae

2007 ◽  
Vol 293 (1) ◽  
pp. H366-H375 ◽  
Author(s):  
MaryEllen Carlile-Klusacek ◽  
Victor Rizzo
Keyword(s):  
Endothelial Cells ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Signaling Cascade ◽  
Membrane Rafts ◽  
Actin Stress Fiber ◽  
Caveolin 1 ◽  
Stress Fiber Formation ◽  
Mlc Phosphorylation ◽  
Actin Stress Fiber Formation

The vasoactive protease thrombin is a known activator of the protease-activated receptor-1 (PAR1) via cleavage of its NH2 terminus. PAR1 activation stimulates the RhoA/Rho kinase signaling cascade, leading to myosin light chain (MLC) phosphorylation, actin stress fiber formation, and changes in endothelial monolayer integrity. Previous studies suggest that some elements of this signaling pathway are localized to caveolin-containing cholesterol-rich membrane domains. Here we show that PAR1 and key components of the PAR-associated signaling cascade localize to membrane rafts and caveolae in bovine aortic endothelial cells (BAEC). To investigate the functional significance of this localization, BAEC were pretreated with filipin (5 μg/ml, 5 min) to ablate lipid rafts before thrombin (100 nM) or PAR agonist stimulation. We found that diphosphorylation of MLC and the actin stress fiber formation normally induced by PAR activation were attenuated after lipid raft disruption. To target caveolae specifically, we used a small interferring RNA approach to knockdown caveolin-1 expression. Thrombin-induced MLC phosphorylation and stress fiber formation were not altered in caveolin-1-depleted cells, suggesting that lipid rafts, but not necessarily caveolae, modulate thrombin-activated signaling pathways leading to alteration of the actin cytoskeleton in endothelial cells.

scholarly journals Impact of Pigment Dispersion on Trabecular Meshwork Cells

2018 ◽  
Author(s):  
Chao Wang ◽  
Yalong Dang ◽  
Ralitsa Loewen ◽  
Susannah Waxman ◽  
Priyal Shah ◽  
...  
Keyword(s):  
Trabecular Meshwork ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Signaling Cascades ◽  
Pigment Dispersion ◽  
Pigmentary Glaucoma ◽  
Trabecular Meshwork Cells ◽  
Stress Fiber Formation ◽  
Ab Interno Trabeculectomy ◽  
And Migration

Purpose: To investigate the effect of pigment dispersion on trabecular meshwork (TM) cells. Methods: Porcine TM cells from ab interno trabeculectomy specimens were exposed to pigment dispersion, then analyzed for changes in morphology, immunostaining, and ultrastructure. Their abilities to phagocytose, migrate, and contract were quantified. An expression microarray, using 23,937 probes, and a pathway analysis were performed. Results: TM cells readily phagocytosed pigment granules. Pigment induced stress fiber formation (pigment (P): 60.1 ± 0.3%, n = 10, control (C): 38.4 ± 2.5%, n = 11, P < 0.001) and contraction at 24 hours onward (P < 0.01). Phagocytosis declined (P: 68.7 ± 1.3%, C: 37.0 ± 1.1%, n = 3, P < 0.001) and migration was reduced after 6 hours (P: 28.0.1 ± 2.3, n = 12, C: 40.6 ± 3.3, n = 13, P < 0.01). Microarray analysis revealed that Rho, IGF-1, and TGFβ signaling cascades were central to these responses. Conclusions: TM cell exposure to pigment dispersion resulted in reduced phagocytosis and migration, as well as increased stress fiber formation and cell contraction. The Rho signaling pathway played a central and early role, suggesting that its inhibitors could be used as a specific intervention in treatment of pigmentary glaucoma.

Regulation of the RhoA pathway in human endothelial cell spreading on type IV collagen: role of calcium influx

1999 ◽  
Vol 112 (19) ◽  
pp. 3205-3213 ◽  
Author(s):  
L. Masiero ◽  
K.A. Lapidos ◽  
I. Ambudkar ◽  
E.C. Kohn
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Focal Adhesion ◽  
Type Iv Collagen ◽  
Cell Spreading ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Type Iv ◽  
Stress Fiber Formation

We have shown that nonvoltage-operated Ca(2+) entry regulates human umbilical vein endothelial cell adhesion, migration, and proliferation on type IV collagen. We now demonstrate a requirement for Ca(2+) influx for activation of the RhoA pathway during endothelial cell spreading on type IV collagen. Reorganization of actin into stress fibers was complete when the cells where fully spread at 90 minutes. No actin organization into stress fibers was seen in endothelial cells plated on type I collagen, indicating a permissive effect of type IV collagen. CAI, a blocker of nonvoltage-operated Ca(2+) channels, prevented development of stress fiber formation in endothelial cells on type IV collagen. This permissive effect was augmented by Ca(2+) influx, as stimulated by 0. 5 microM thapsigargin or 0.1 microM ionomycin, yielding faster development of actin stress fibers. Ca(2+) influx and actin rearrangement in response to thapsigargin and ionomycin were abrogated by CAI. Activated, membrane-bound RhoA is a substrate for C3 exoenzyme which ADP-ribosylates and inactivates RhoA, preventing actin stress fiber formation. Pretreatment of endothelial cells with C3 exoenzyme prevented basal and thapsigargin-augmented stress fiber formation. While regulation of Ca(2+) influx did not alter RhoA translocation, it reduced in vitro ADP-ribosylation of RhoA (P(2)<0. 05), suggesting Ca(2+) influx is needed for RhoA activation during spreading on type IV collagen; no Ca(2+) regulated change in RhoA was seen in HUVECs spreading on type I collagen matrix. Blockade of Ca(2+) influx of HUVEC spread on type IV collagen also reduced tyrosine phosphorylation of p190Rho-GAP and blocked thapsigargin-enhanced binding of p190Rho-GAP to focal adhesion kinase. Thus, Ca(2+) influx is necessary for RhoA activation and for linkage of the RhoA/stress fiber cascade to the focal adhesion/focal adhesion kinase pathway during human umbilical vein endothelial cell spreading on type IV collagen.

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