The Experts below are selected from a list of 70212 Experts worldwide ranked by ideXlab platform
Shoukat Dedhar - One of the best experts on this subject based on the ideXlab platform.
-
integrin linked kinase activity regulates rac and cdc42 mediated Actin Cytoskeleton reorganization via alpha pix
Oncogene, 2005Co-Authors: Nolan R Filipenko, Sarah Attwell, Calvin D. Roskelley, Shoukat DedharAbstract:Cell spreading and migration are regulated in a Rho family GTPase-dependent manner by growth factors and integrin-mediated cell-extracellular matrix (ECM) interactions. The molecular mechanisms involved in the ECM- and growth factor-mediated activation of these small GTPases remain unclear. In the present study, we demonstrate that integrin-linked kinase (ILK), which is a focal adhesion protein activated by both ECM and growth factors, is required for the activation of Rac and Cdc42 in epithelial cells. Ectopic expression of active ILK in mammary epithelial cells induces dramatic reorganization of the Actin Cytoskeleton and promotes rapid cell spreading on fibronectin. These effects are associated with constitutive activation of both Rac and Cdc42, but not Rho. The use of ILK siRNA or small molecule inhibitors to inhibit ILK expression and kinase activity, respectively, results in diminished cell spreading and Actin Cytoskeleton reorganization, concomitant with a reduction in Rac and Cdc42 activation. Studies into the mechanism of ILK-mediated Rac activation suggest an important role for the ILK-beta-parvin interaction and the activity of the Rac/Cdc42-specific guanine nucleotide exchange factor alpha-PIX downstream of ILK. Taken together, these data demonstrate an essential role of ILK kinase activity in Rac- and Cdc42-mediated Actin Cytoskeleton reorganization in epithelial cells, further solidifying a role for ILK in the regulation of cancer cell motility and invasiveness.
-
integrin linked kinase activity regulates rac and cdc42 mediated Actin Cytoskeleton reorganization via alpha pix
Oncogene, 2005Co-Authors: Nolan R Filipenko, Sarah Attwell, Calvin D. Roskelley, Shoukat DedharAbstract:Cell spreading and migration are regulated in a Rho family GTPase-dependent manner by growth factors and integrin-mediated cell–extracellular matrix (ECM) interactions. The molecular mechanisms involved in the ECM- and growth factor-mediated activation of these small GTPases remain unclear. In the present study, we demonstrate that integrin-linked kinase (ILK), which is a focal adhesion protein activated by both ECM and growth factors, is required for the activation of Rac and Cdc42 in epithelial cells. Ectopic expression of active ILK in mammary epithelial cells induces dramatic reorganization of the Actin Cytoskeleton and promotes rapid cell spreading on fibronectin. These effects are associated with constitutive activation of both Rac and Cdc42, but not Rho. The use of ILK siRNA or small molecule inhibitors to inhibit ILK expression and kinase activity, respectively, results in diminished cell spreading and Actin Cytoskeleton reorganization, concomitant with a reduction in Rac and Cdc42 activation. Studies into the mechanism of ILK-mediated Rac activation suggest an important role for the ILK–β-parvin interaction and the activity of the Rac/Cdc42-specific guanine nucleotide exchange factor α-PIX downstream of ILK. Taken together, these data demonstrate an essential role of ILK kinase activity in Rac- and Cdc42-mediated Actin Cytoskeleton reorganization in epithelial cells, further solidifying a role for ILK in the regulation of cancer cell motility and invasiveness.
Taihao Quan - One of the best experts on this subject based on the ideXlab platform.
-
Actin Cytoskeleton assembly regulates collagen production via tgf β type ii receptor in human skin fibroblasts
Journal of Cellular and Molecular Medicine, 2018Co-Authors: Zhaoping Qin, Gary J Fisher, John J Voorhees, Taihao QuanAbstract:The dermal compartment of skin is primarily composed of collagen-rich extracellular matrix (ECM), which is produced by dermal fibroblasts. In Young skin, fibroblasts attach to the ECM through integrins. During ageing, fragmentation of the dermal ECM limits fibroblast attachment. This reduced attachment is associated with decreased collagen production, a major cause of skin thinning and fragility, in the elderly. Fibroblast attachment promotes assembly of the cellular Actin Cytoskeleton, which generates mechanical forces needed for structural support. The mechanism(s) linking reduced assembly of the Actin Cytoskeleton to decreased collagen production remains unclear. Here, we report that disassembly of the Actin Cytoskeleton results in impairment of TGF-β pathway, which controls collagen production, in dermal fibroblasts. Cytoskeleton disassembly rapidly down-regulates TGF-β type II receptor (TβRII) levels. This down-regulation leads to reduced activation of downstream effectors Smad2/Smad3 and CCN2, resulting in decreased collagen production. These responses are fully reversible; restoration of Actin Cytoskeleton assembly up-regulates TβRII, Smad2/Smad3, CCN2 and collagen expression. Finally, Actin Cytoskeleton-dependent reduction of TβRII is mediated by induction of microRNA 21, a potent inhibitor of TβRII protein expression. Our findings reveal a novel mechanism that links Actin Cytoskeleton assembly and collagen expression in dermal fibroblasts. This mechanism likely contributes to loss of TβRII and collagen production, which are observed in aged human skin.
Alexander D Bershadsky - One of the best experts on this subject based on the ideXlab platform.
-
cellular chirality arising from the self organization of the Actin Cytoskeleton
Nature Cell Biology, 2015Co-Authors: Tom Shemesh, Visalatchi Thiagarajan, Rizal F Hariadi, Karen L Anderson, Christopher Page, Niels Volkmann, Dorit Hanein, Sivaraj Sivaramakrishnan, Michael M Kozlov, Alexander D BershadskyAbstract:Bershadsky and colleagues show that cells confined to circular adhesive patterns exhibit defined and dynamic self-assembly of their Actin Cytoskeleton into a chiral pattern with defined handedness, potentially informing left–right cell asymmetry.
-
caldesmon effects on the Actin Cytoskeleton and cell adhesion in cultured htm cells
Experimental Eye Research, 2006Co-Authors: Inna Grosheva, Jason L Vittitow, Polina Goichberg, Bann T Gabelt, Paul L Kaufman, T Borras, Benjamin Geiger, Alexander D BershadskyAbstract:Caldesmon is a multifunctional ubiquitous regulator of the Actin Cytoskeleton, which can affect both actomyosin contractility and Actin polymerization. Previous studies showed that caldesmon over-expression in cultured fibroblasts produces effects that resemble those of chemical inhibitors of cellular contractility. Since these inhibitors (H-7, Y-27632, etc.) have been shown to lower intraocular pressure and increase outflow facility from the anterior chamber of the eye, we proposed that caldesmon might be used for gene therapy of glaucoma. In the present study we examined the effects of expression of adenovirus-delivered rat non-muscle caldesmon fused with green fluorescent protein (AdCaldGFP) on the Actin Cytoskeleton and matrix adhesions in cultured human trabecular meshwork (HTM) cells. In addition, we assessed the effect of caldesmon on the stability of cell–cell junctions in kidney epithelial MDCK cells. Cultured HTM cells demonstrate a well-developed Actin Cytoskeleton, comprising mainly arrays of parallel actomyosin bundles (stress fibers). Lamellipodial protrusions containing dense Actin networks are also observed. Cell– matrix adhesions are dominated by focal adhesions (FAs) associated with the ends of the stress fibers, focal complexes in lamellipodia, and fibrillar adhesions in the central part of the spread cells. Treatment of HTM cells with AdCaldGFP resulted in dose-dependent morphological changes within 24–48 hr post-infection. Cells expressing moderate levels of caldesmon exhibited straight bundles containing Actin and myosin II, which were considerably shorter than those in control cells. Short filament bundles in caldesmon over-expressing cells formed arrays consisting of triangular Actin structures with small vinculin-positive FAs at their vertices. In addition, the fraction of cells displaying large lamellipodia increased. About 40– 50% of the population of caldesmon-expressing cells demonstrated high levels of GFP–caldesmon expression and severe changes in the Actin Cytoskeleton, manifested by the disappearance of stress fibers and the formation of curved Actin- and myosin-containing bundles. These bundles formed together a dynamic network consisting of pulsating loops filling the entire cytoplasm. Addition of thapsigargin, which increases intracellular Ca CC concentration, resulted in a straightening of the curved bundles. Another type of novel Actin structures induced by caldesmon over-expression were highly dynamic circular waves that propagated over the affected cells with a velocity about 10 mm min. In cells with disrupted stress fibers, vinculin-containing FAs and tensin-rich fibrillar adhesions had also essentially vanished. However, phosphotyrosine-positive focal complexes were still prominent throughout the lamellipodia of these cells. Over-expression of caldesmon in MDCK cells reduced, in a dose dependent manner, the beta-catenin content at cell–cell adherens junctions and in some cases led to physical disruption of adherens junctions. Thus, caldesmon overexpression induces unique reorganization of the Actin Cytoskeleton in affected cells, accompanied by disruption of focal and fibrillar cell–matrix adhesions, and destabilization of cell–cell adherens junctions. Inducing such changes in the contractility and Actin Cytoskeleton of HTM cells in glaucomatous eyes in vivo could produce a therapeutically useful increase in outflow facility.
Zhaoping Qin - One of the best experts on this subject based on the ideXlab platform.
-
Actin Cytoskeleton assembly regulates collagen production via tgf β type ii receptor in human skin fibroblasts
Journal of Cellular and Molecular Medicine, 2018Co-Authors: Zhaoping Qin, Gary J Fisher, John J Voorhees, Taihao QuanAbstract:The dermal compartment of skin is primarily composed of collagen-rich extracellular matrix (ECM), which is produced by dermal fibroblasts. In Young skin, fibroblasts attach to the ECM through integrins. During ageing, fragmentation of the dermal ECM limits fibroblast attachment. This reduced attachment is associated with decreased collagen production, a major cause of skin thinning and fragility, in the elderly. Fibroblast attachment promotes assembly of the cellular Actin Cytoskeleton, which generates mechanical forces needed for structural support. The mechanism(s) linking reduced assembly of the Actin Cytoskeleton to decreased collagen production remains unclear. Here, we report that disassembly of the Actin Cytoskeleton results in impairment of TGF-β pathway, which controls collagen production, in dermal fibroblasts. Cytoskeleton disassembly rapidly down-regulates TGF-β type II receptor (TβRII) levels. This down-regulation leads to reduced activation of downstream effectors Smad2/Smad3 and CCN2, resulting in decreased collagen production. These responses are fully reversible; restoration of Actin Cytoskeleton assembly up-regulates TβRII, Smad2/Smad3, CCN2 and collagen expression. Finally, Actin Cytoskeleton-dependent reduction of TβRII is mediated by induction of microRNA 21, a potent inhibitor of TβRII protein expression. Our findings reveal a novel mechanism that links Actin Cytoskeleton assembly and collagen expression in dermal fibroblasts. This mechanism likely contributes to loss of TβRII and collagen production, which are observed in aged human skin.
Dora B. Krimer - One of the best experts on this subject based on the ideXlab platform.
-
crispr cas9 mediated deletion of the wiskott aldrich syndrome locus causes Actin Cytoskeleton disorganization in murine erythroleukemia cells
PeerJ, 2019Co-Authors: Vanessa Fernandezcalleja, Jorge B. Schvartzman, Maria Jose Fernandeznestosa, Pablo E Hernandez, Dora B. KrimerAbstract:Wiskott-Aldrich syndrome (WAS) is a recessive X-linked inmmunodeficiency caused by loss-of-function mutations in the gene encoding the WAS protein (WASp). WASp plays an important role in the polymerization of the Actin Cytoskeleton in hematopoietic cells through activation of the Arp2/3 complex. In a previous study, we found that Actin Cytoskeleton proteins, including WASp, were silenced in murine erythroleukemia cells defective in differentiation. Here, we designed a CRISPR/Cas9 strategy to delete a 9.5-kb genomic region encompassing the Was gene in the X chromosome of murine erythroleukemia (MEL) cells. We show that Was-deficient MEL cells have a poor organization of the Actin Cytoskeleton that can be recovered by restoring Was expression. We found that whereas the total amount of Actin protein was similar between wild-type and Was knockout MEL cells, the latter exhibited an altered ratio of monomeric G-Actin to polymeric F-Actin. We also demonstrate that Was overexpression can mediate the activation of Bruton's tyrosine kinase. Overall, these findings support the role of WASp as a key regulator of F-Actin in erythroid cells.
-
CRISPR/Cas9-mediated deletion of the Wiskott-Aldrich syndrome locus causes Actin Cytoskeleton disorganization in murine erythroleukemia cells
PeerJ Inc., 2019Co-Authors: Vanessa Fernández-calleja, María-josé Fernández-nestosa, Pablo Hernández, Jorge B. Schvartzman, Dora B. KrimerAbstract:Wiskott-Aldrich syndrome (WAS) is a recessive X-linked inmmunodeficiency caused by loss-of-function mutations in the gene encoding the WAS protein (WASp). WASp plays an important role in the polymerization of the Actin Cytoskeleton in hematopoietic cells through activation of the Arp2/3 complex. In a previous study, we found that Actin Cytoskeleton proteins, including WASp, were silenced in murine erythroleukemia cells defective in differentiation. Here, we designed a CRISPR/Cas9 strategy to delete a 9.5-kb genomic region encompassing the Was gene in the X chromosome of murine erythroleukemia (MEL) cells. We show that Was-deficient MEL cells have a poor organization of the Actin Cytoskeleton that can be recovered by restoring Was expression. We found that whereas the total amount of Actin protein was similar between wild-type and Was knockout MEL cells, the latter exhibited an altered ratio of monomeric G-Actin to polymeric F-Actin. We also demonstrate that Was overexpression can mediate the activation of Bruton’s tyrosine kinase. Overall, these findings support the role of WASp as a key regulator of F-Actin in erythroid cells
