scholarly journals Artemether Targets Raptor-Induced Actin Polymerization and Suppresses Migration of Fibroblast-like Synoviocytes in Rheumatoid Arthritis

2021 ◽  
Author(s):  
Jian-Da Ma ◽  
Jun Jing ◽  
Jun-Wei Wang ◽  
Xue-Pei Zhang ◽  
Qian-Hua Li ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Rho Gtpases ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Rho Gtpase ◽  
Actin Binding ◽  
Migration And Invasion ◽  
Actin Binding Proteins ◽  
Activation Assay ◽  
Fibroblast Like Synoviocytes

Abstract Background: Fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA) may cause articular damage as a result of its aggressive features including direct adhesion and invasion of surface cartilage in joints. Artemether (ART), one of the artemisinin derivatives with antimalarial properties, showed inhibitory effect on inflammation and destruction of joints in collagen-induced arthritis rats, which might be applied in RA treatment. However, whether ART has effects on the aggressive properties of human RA-FLS remains unexplored. Methods: Synovium was obtained from patients with active RA (n=18) and FLS were isolated in vitro. RA-FLS were subjected to cell migration, invasion assays, live-cell imaging analysis and Rho GTPase activation assay after ART treatment. To identify the therapeutic target of ART, key signaling molecules of PI3K/Akt, AMPK, MAPK, NF-κB and mTOR pathways from RA-FLS were examined by Western Blot after ART treatment. Raptor was knockdown or overexpressed by siRNA or lentivirus transfection to reveal its role on regulating the aggressive properties of RA-FLS.Results: ART treatment significantly suppressed the transwell migration and invasion of synovial FLS from RA patients. Time-lapse microscopy revealed that ART treatment reduced random migration velocity of RA-FLS, as well as the directional persistence. ART also impaired the formation of filopodia and lamellipodia in RA-FLS. Further mechanism investigation showed that ART reduced the protein level of Raptor, a critical component of the mTOR pathway, and its downstream target 4E-BP1. It also inhibited the activation of Rho GTPases and the expression of actin binding proteins, including Profilin 1 and p-Cofilin. Raptor overexpression could reverse the anti-migration and anti-invasion effects of ART on RA-FLS as well as the suppression of Rho GTPases activation and the expression of actin binding proteins. Conclusion: ART can inhibit migration of RA-FLS by blocking Raptor-induced actin polymerization. ART might be a potential agent targeting FLS in RA treatment.

scholarly journals Direct Visualization of Actin Filaments and Actin-Binding Proteins in Neuronal Cells

2020 ◽  
Vol 8 ◽  
Author(s):  
Minkyo Jung ◽  
Doory Kim ◽  
Ji Young Mun
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Light And Electron Microscopy ◽  
Super Resolution ◽  
Actin Binding ◽  
Direct Visualization ◽  
Actin Binding Proteins ◽  
Synapse Plasticity

Actin networks and actin-binding proteins (ABPs) are most abundant in the cytoskeleton of neurons. The function of ABPs in neurons is nucleation of actin polymerization, polymerization or depolymerization regulation, bundling of actin through crosslinking or stabilization, cargo movement along actin filaments, and anchoring of actin to other cellular components. In axons, ABP–actin interaction forms a dynamic, deep actin network, which regulates axon extension, guidance, axon branches, and synaptic structures. In dendrites, actin and ABPs are related to filopodia attenuation, spine formation, and synapse plasticity. ABP phosphorylation or mutation changes ABP–actin binding, which regulates axon or dendritic plasticity. In addition, hyperactive ABPs might also be expressed as aggregates of abnormal proteins in neurodegeneration. Those changes cause many neurological disorders. Here, we will review direct visualization of ABP and actin using various electron microscopy (EM) techniques, super resolution microscopy (SRM), and correlative light and electron microscopy (CLEM) with discussion of important ABPs in neuron.

scholarly journals Mapping the binding site of thymosin β4 on actin by competition with G-actin binding proteins indicates negative co-operativity between binding sites located on opposite subdomains of actin

1997 ◽  
Vol 327 (3) ◽  
pp. 787-793 ◽  
Author(s):  
Edda BALLWEBER ◽  
Ewald HANNAPPEL ◽  
Thomas HUFF ◽  
Hans Georg MANNHERZ
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Ternary Complex ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Critical Concentration ◽  
Dnase I ◽  
Actin Binding ◽  
Thymosin Β4 ◽  
Actin Binding Proteins

The β-thymosins are small monomeric (G-)actin-binding proteins of 5 kDa that are supposed to act intracellularly as actin-sequestering factors stabilizing the cytoplasmic monomeric pool of actin. The binding region of thymosin β4 was determined by analysing the binding of thymosin β4 to actin complexed with DNase I, gelsolin or gelsolin segment 1. Binding was analysed by determining the increase in the critical concentration of actin polymerization by native gel electrophoresis or chemical cross-linking. The formation of a ternary complex including thymosin β4 should indicate that the actin-binding proteins attach to different sites on actin. Competition would be indicative of binding to identical or overlapping sites on actin or of a negative co-operative linkage between the two binding sites. Competition of thymosin β4 for actin binding was observed in the presence of intact gelsolin or the N-terminal gelsolin fragment, segment 1, indicating that thymosin β4 binds to a site close to or identical with the gelsolin segment 1-binding site. The ternary complex of actin-DNase I-thymosin β4 was obtained only when using the chemically cross-linked actin-thymosin β4 complex, indicating that thymosin β4 is dissociated by the binding of DNase I to actin. It is suggested that the dissociation of thymosin β4 by DNase I binding to actin is caused by negative co-operativity between their spatially separated binding sites on actin. A similar negative co-operativity was observed between DNase I and gelsolin segment 1 binding to actin. The results therefore indicate that the respective binding sites for DNase I and segment 1 on subdomains 1 and 2 of actin are linked in a negative co-operative manner.

scholarly journals Involvement of Actin and Actin-Binding Proteins in Carcinogenesis

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2245 ◽  
Author(s):  
Magdalena Izdebska ◽  
Wioletta Zielińska ◽  
Marta Hałas-Wiśniewska ◽  
Alina Grzanka
Keyword(s):  
Cancer Cells ◽  
Binding Proteins ◽  
Initial Step ◽  
Actin Binding ◽  
Migration And Invasion ◽  
Filamin A ◽  
Actin Binding Proteins ◽  
Promote Cell Proliferation ◽  
Cellular Processes ◽  
Associated Proteins

The actin cytoskeleton plays a crucial role in many cellular processes while its reorganization is important in maintaining cell homeostasis. However, in the case of cancer cells, actin and ABPs (actin-binding proteins) are involved in all stages of carcinogenesis. Literature has reported that ABPs such as SATB1 (special AT-rich binding protein 1), WASP (Wiskott-Aldrich syndrome protein), nesprin, and villin take part in the initial step of carcinogenesis by regulating oncogene expression. Additionally, changes in actin localization promote cell proliferation by inhibiting apoptosis (SATB1). In turn, migration and invasion of cancer cells are based on the formation of actin-rich protrusions (Arp2/3 complex, filamin A, fascin, α-actinin, and cofilin). Importantly, more and more scientists suggest that microfilaments together with the associated proteins mediate tumor vascularization. Hence, the presented article aims to summarize literature reports in the context of the potential role of actin and ABPs in all steps of carcinogenesis.

What is in a filopodium? Starfish versus hedgehogs

2004 ◽  
Vol 32 (6) ◽  
pp. 1115-1117 ◽  
Author(s):  
S. Passey ◽  
S. Pellegrin ◽  
H. Mellor
Keyword(s):  
Rho Gtpases ◽  
Binding Proteins ◽  
Cell Types ◽  
General Term ◽  
Actin Binding ◽  
Signalling Pathways ◽  
Actin Binding Proteins ◽  
Different Types

Many cell types can generate thin actin-based protrusive structures, which are often classified under the general term of ‘filopodia’. However, a range of filopodia-like structures exists that differ both morphologically and functionally. In this brief review, we discuss the different types of filopodial structures, together with the actin-binding proteins and signalling pathways involved in their formation. Specifically, we highlight the differences between the filopodial extensions induced by the Rho GTPases Cdc42 and Rif.

scholarly journals The actin regulator profilin 1 is functionally associated with the mammalian centrosome

2020 ◽  
Vol 4 (1) ◽  
pp. e202000655
Author(s):  
Michaela Nejedlá ◽  
Anastasiya Klebanovych ◽  
Vadym Sulimenko ◽  
Tetyana Sulimenko ◽  
Eduarda Dráberová ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Binding Proteins ◽  
Actin Binding ◽  
Cell Periphery ◽  
Microtubule Nucleation ◽  
Microtubule Organization ◽  
Actin Binding Proteins ◽  
Cell Edge ◽  
It Impacts ◽  
Microtubule Growth

Profilin 1 is a crucial actin regulator, interacting with monomeric actin and several actin-binding proteins controlling actin polymerization. Recently, it has become evident that this profilin isoform associates with microtubules via formins and interferes with microtubule elongation at the cell periphery. Recruitment of microtubule-associated profilin upon extensive actin polymerizations, for example, at the cell edge, enhances microtubule growth, indicating that profilin contributes to the coordination of actin and microtubule organization. Here, we provide further evidence for the profilin-microtubule connection by demonstrating that it also functions in centrosomes where it impacts on microtubule nucleation.

Actin-binding proteins sensitively mediate actin bundle stiffness

2006 ◽  
Vol 39 ◽  
pp. S240
Author(s):  
M. Bathe ◽  
M. Claessens ◽  
E. Frey ◽  
A. Bausch
Keyword(s):  
Binding Proteins ◽  
Actin Binding ◽  
Actin Binding Proteins ◽  
Actin Bundle
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