scholarly journals Automatic Actin Filament Quantification and Cell Shape Modeling of Osteoblasts on Charged Ti Surfaces

2021 ◽  
Vol 11 (12) ◽  
pp. 5689
Author(s):  
Martina Gruening ◽  
Jonathan E. Dawson ◽  
Christian Voelkner ◽  
Sven Neuber ◽  
Katja Fricke ◽  
...  
Keyword(s):  
Actin Filament ◽  
Cell Shape ◽  
Adhesion Forces ◽  
Surface Charges ◽  
Cellular Functions ◽  
Ion Conductance ◽  
Cortical Tension ◽  
Scanning Ion Conductance Microscopy ◽  
Charged Surfaces ◽  
The Impact

Surface charges at the cell–biomaterial interface are known to determine cellular functions. Previous findings on cell signaling indicate that osteoblastic cells favor certain moderately positive surface charges, whereas highly positive charges are not tolerated. In this study, we aimed to gain deeper insights into the influence exerted by surface charges on the actin cytoskeleton and the cell shape. We analyzed surfaces with a negative, moderately positive, and highly positive zeta (ζ) potential: titanium (Ti), Ti with plasma polymerized allylamine (PPAAm), and Ti with a polydiallyldimethylammonium chloride (PDADMA) multilayer, respectively. We used the software FilaQuant for automatic actin filament quantification of osteoblastic MG-63s, analyzed the cell edge height with scanning ion conductance microscopy (SICM), and described the cellular shape via a mathematical vertex model. A significant enhancement of actin filament formation was achieved on moderately positive (+7 mV) compared with negative ζ-potentials (−87 mV). A hampered cell spreading was reflected in a diminished actin filament number and length on highly positively charged surfaces (+50 mV). Mathematical simulations suggested that in these cells, cortical tension forces dominate the cell–substrate adhesion forces. Our findings present new insights into the impact of surface charges on the overall cell shape and even intracellular structures.

Simultaneous mapping of nanoscale topography and surface potential of charged surfaces by scanning ion conductance microscopy

Nanoscale ◽  
2020 ◽  
Vol 12 (40) ◽  
pp. 20737-20748
Author(s):  
Feng Chen ◽  
Namuna Panday ◽  
Xiaoshuang Li ◽  
Tao Ma ◽  
Jing Guo ◽  
...  
Keyword(s):  
Surface Potential ◽  
Ion Conductance ◽  
Physiological Conditions ◽  
Scanning Ion Conductance Microscopy ◽  
Charged Surfaces ◽  
Nanoscale Topography

Simultaneous mapping of nanoscale topography and surface potential of soft, rough and heterogeneously charged surfaces under physiological conditions.

scholarly journals Cell stiffness and ROS level alterations in living neurons mediated by β-amyloid oligomers measured by scanning ion-conductance microscopy.

2021 ◽  
Vol 27 (S1) ◽  
pp. 500-502
Author(s):  
Oleg Suchalko ◽  
Roman Timoshenko ◽  
Alexander Vaneev ◽  
Vasilii Kolmogorov ◽  
Nikita Savin ◽  
...  
Keyword(s):  
Cell Stiffness ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Amyloid Oligomers ◽  
Β Amyloid ◽  
Living Neurons

scholarly journals Nanoscale Cell Membrane Fluctuations Measured by Scanning Ion Conductance Microscopy

2013 ◽  
Vol 104 (2) ◽  
pp. 317a
Author(s):  
Yusuke Mizutani ◽  
Zen Ishikura ◽  
Myung-Hoon Choi ◽  
Sang-Joon Cho ◽  
Takaharu Okajima
Keyword(s):  
Cell Membrane ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Membrane Fluctuations

scholarly journals Actin cytoskeleton deregulation confers midostaurin resistance in FLT3-mutant acute myeloid leukemia

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Andoni Garitano-Trojaola ◽  
Ana Sancho ◽  
Ralph Götz ◽  
Patrick Eiring ◽  
Susanne Walz ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Actin Cytoskeleton ◽  
Myeloid Leukemia ◽  
Actin Polymerization ◽  
Cell Stiffness ◽  
Adhesion Forces ◽  
Frequent Mutations ◽  
New Perspective ◽  
The Impact ◽  
Acute Myeloid

AbstractThe presence of FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) is one of the most frequent mutations in acute myeloid leukemia (AML) and is associated with an unfavorable prognosis. FLT3 inhibitors, such as midostaurin, are used clinically but fail to entirely eradicate FLT3-ITD + AML. This study introduces a new perspective and highlights the impact of RAC1-dependent actin cytoskeleton remodeling on resistance to midostaurin in AML. RAC1 hyperactivation leads resistance via hyperphosphorylation of the positive regulator of actin polymerization N-WASP and antiapoptotic BCL-2. RAC1/N-WASP, through ARP2/3 complex activation, increases the number of actin filaments, cell stiffness and adhesion forces to mesenchymal stromal cells (MSCs) being identified as a biomarker of resistance. Midostaurin resistance can be overcome by a combination of midostaruin, the BCL-2 inhibitor venetoclax and the RAC1 inhibitor Eht1864 in midostaurin-resistant AML cell lines and primary samples, providing the first evidence of a potential new treatment approach to eradicate FLT3-ITD + AML.

scholarly journals Anomalous Laterally Stressed Kinetically Trapped DNA Surface Conformations

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Valery V. Prokhorov ◽  
Nikolay A. Barinov ◽  
Kirill A. Prusakov ◽  
Evgeniy V. Dubrovin ◽  
Maxim D. Frank-Kamenetskii ◽  
...  
Keyword(s):  
Electrostatic Interaction ◽  
Mechanical Response ◽  
Persistence Length ◽  
Strong Impact ◽  
List Type ◽  
Surface Charges ◽  
Monomolecular Films ◽  
Chain Approximation ◽  
The Impact ◽  
Positively Charged

Highlights DNA kinking is inevitable for the highly anisotropic 1D–1D electrostatic interaction with the one-dimensionally periodically charged surface. The double helical structure of the DNA kinetically trapped on positively charged monomolecular films comprising the lamellar templates is strongly laterally stressed and extremely perturbed at the nanometer scale. The DNA kinetic trapping is not a smooth 3D—> 2D conformational flattening but is a complex nonlinear in-plane mechanical response (bending, tensile and unzipping) driven by the physics beyond the scope of the applicability of the linear worm-like chain approximation. Abstract Up to now, the DNA molecule adsorbed on a surface was believed to always preserve its native structure. This belief implies a negligible contribution of lateral surface forces during and after DNA adsorption although their impact has never been elucidated. High-resolution atomic force microscopy was used to observe that stiff DNA molecules kinetically trapped on monomolecular films comprising one-dimensional periodically charged lamellar templates as a single layer or as a sublayer are oversaturated by sharp discontinuous kinks and can also be locally melted and supercoiled. We argue that kink/anti-kink pairs are induced by an overcritical lateral bending stress (> 30 pNnm) inevitable for the highly anisotropic 1D-1D electrostatic interaction of DNA and underlying rows of positive surface charges. In addition, the unexpected kink-inducing mechanical instability in the shape of the template-directed DNA confined between the positively charged lamellar sides is observed indicating the strong impact of helicity. The previously reported anomalously low values of the persistence length of the surface-adsorbed DNA are explained by the impact of the surface-induced low-scale bending. The sites of the local melting and supercoiling are convincingly introduced as other lateral stress-induced structural DNA anomalies by establishing a link with DNA high-force mechanics. The results open up the study in the completely unexplored area of the principally anomalous kinetically trapped DNA surface conformations in which the DNA local mechanical response to the surface-induced spatially modulated lateral electrostatic stress is essentially nonlinear. The underlying rich and complex in-plane nonlinear physics acts at the nanoscale beyond the scope of applicability of the worm-like chain approximation.

scholarly journals A novel role for WAVE1 in controlling actin network growth rate and architecture

2015 ◽  
Vol 26 (3) ◽  
pp. 495-505 ◽  
Author(s):  
Meredith O. Sweeney ◽  
Agnieszka Collins ◽  
Shae B. Padrick ◽  
Bruce L. Goode
Keyword(s):  
Actin Filament ◽  
Specific Activity ◽  
Inhibitory Effect ◽  
Actin Network ◽  
Inhibitory Effects ◽  
Cellular Functions ◽  
Network Growth ◽  
Assembly Kinetics ◽  
Filament Networks ◽  
First Time

Branched actin filament networks in cells are assembled through the combined activities of Arp2/3 complex and different WASP/WAVE proteins. Here we used TIRF and electron microscopy to directly compare for the first time the assembly kinetics and architectures of actin filament networks produced by Arp2/3 complex and dimerized VCA regions of WAVE1, WAVE2, or N-WASP. WAVE1 produced strikingly different networks from WAVE2 or N-WASP, which comprised unexpectedly short filaments. Further analysis showed that the WAVE1-specific activity stemmed from an inhibitory effect on filament elongation both in the presence and absence of Arp2/3 complex, which was observed even at low stoichiometries of WAVE1 to actin monomers, precluding an effect from monomer sequestration. Using a series of VCA chimeras, we mapped the elongation inhibitory effects of WAVE1 to its WH2 (“V”) domain. Further, mutating a single conserved lysine residue potently disrupted WAVE1's inhibitory effects. Taken together, our results show that WAVE1 has unique activities independent of Arp2/3 complex that can govern both the growth rates and architectures of actin filament networks. Such activities may underlie previously observed differences between the cellular functions of WAVE1 and WAVE2.

scholarly journals Frabin, a Novel FGD1-related Actin Filament-binding Protein Capable of Changing Cell Shape and Activating c-Jun N-terminal Kinase

1998 ◽  
Vol 273 (30) ◽  
pp. 18697-18700 ◽  
Author(s):  
Hiroshi Obaishi ◽  
Hiroyuki Nakanishi ◽  
Kenji Mandai ◽  
Keiko Satoh ◽  
Ayako Satoh ◽  
...  
Keyword(s):  
Actin Filament ◽  
Cell Shape ◽  
Binding Protein
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