Actin isoforms in the parasitic nematodeHaemonchus contortus

We have shown previously that two cytoplasmic actin isoforms play different roles in neoplastic cell transformation. Namely, β-cytoplasmic actin acts as a tumor suppressor, whereas γ-cytoplasmic actin enhances malignant features of tumor cells. The distinct participation of each cytoplasmic actin in the cell cycle driving was also observed. The goal of this study was to describe the diverse roles of cytoplasmic actins in the progression of chromosomal instability of MDA-MB-231 basal-like human carcinoma cell line. We performed traditional methods of chromosome visualization, as well as 3D-IF microscopy and western blotting for CENP-A detection/quantification, to investigate chromosome morphology. Downregulation of cytoplasmic actin isoforms alters the phenotype and karyotype of MDA-MB-231 breast cancer cells. Moreover, β-actin depletion leads to the progression of chromosomal instability with endoreduplication and aneuploidy increase. On the contrary, γ-actin downregulation results not only in reduced percentage of mitotic carcinoma cells, but leads to chromosome stability, reduced polyploidy, and aneuploidy.

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Phalloidin Binding and Rheological Differences among Actin Isoforms†

Biochemistry ◽

10.1021/bi961326g ◽

1996 ◽

Vol 35 (45) ◽

pp. 14062-14069 ◽

Cited By ~ 40

Author(s):

P. G. Allen ◽

C. B. Shuster ◽

J. Käs ◽

C. Chaponnier ◽

P. A. Janmey ◽

...

Keyword(s):

Actin Isoforms

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ADP-ribosylation of actin isoforms by Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1990.tb19448.x ◽

1990 ◽

Vol 194 (1) ◽

pp. 237-241 ◽

Cited By ~ 58

Author(s):

Stefan MAUSS ◽

Christine CHAPONNIER ◽

Ingo JUST ◽

Klaus AKTORIES ◽

Giulio GABBIANI

Keyword(s):

Clostridium Perfringens ◽

Clostridium Botulinum ◽

Actin Isoforms ◽

Adp Ribosylation ◽

Clostridium Botulinum C2 Toxin ◽

Clostridium Perfringens Iota Toxin ◽

C2 Toxin

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Abstract P485: Loss Of Acta2 In Cardiac Fibroblasts Does Not Prevent The Myofibroblast Differentiation Or Affect The Cardiac Repair After Myocardial Infarction

Circulation Research ◽

10.1161/res.129.suppl_1.p485 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Yuxia Li ◽

Chaoyang Li ◽

Qianglin Liu ◽

Leshan Wang ◽

Adam X Bao ◽

...

Keyword(s):

Myocardial Infarction ◽

Cardiac Fibroblasts ◽

Cardiac Repair ◽

Fiber Formation ◽

Stress Fibers ◽

Myofibroblast Differentiation ◽

Filamentous Actin ◽

Actin Isoforms ◽

Cytoplasmic Actin ◽

Cardiac Myofibroblasts

In response to myocardial infarction (MI), quiescent cardiac fibroblasts differentiate into myofibroblasts mediating tissue repair in the infarcted area. One of the most widely accepted markers of myofibroblast differentiation is the expression of Acta2 which encodes smooth muscle alpha-actin (SMαA) that is assembled into stress fibers. However, the requirement of Acta2 / SMαA in the myofibroblast differentiation of cardiac fibroblasts and its role in post-MI cardiac repair remained largely unknown. To answer these questions, we generated a tamoxifen-inducible cardiac fibroblast-specific Acta2 knockout mouse line. Surprisingly, mice that lacked Acta2 in cardiac fibroblasts had a normal survival rate after MI. Moreover, Acta2 deletion did not affect the function or overall histology of infarcted hearts. No difference was detected in the proliferation, migration, or contractility between WT and Acta2 -null cardiac myofibroblasts. It was identified that Acta2 -null cardiac myofibroblasts had a normal total filamentous actin level and total actin level. Acta2 deletion caused a unique compensatory increase in the transcription level of Actg2 and an increase in the protein level of sarcomeric actin isoform(s). In addition, the specific muscle actin isoforms that were upregulated in Acta2 -null cardiac myofibroblasts varied between individual cells. Moreover, the formation of stress fibers by cytoplasmic actin isoforms, especially the cytoplasmic gamma-actin, was enhanced in Acta2 -null cardiac myofibroblasts despite their unchanged RNA and protein expression. In conclusion, the deletion of Acta2 does not prevent the myofibroblast differentiation of cardiac fibroblasts or affect the post-MI cardiac repair, and the increased expression and stress fiber formation of non-SMαA actin isoforms and the functional redundancy between actin isoforms are able to compensate for the loss of Acta2 in cardiac myofibroblasts.

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Divergent Impact of Actin Isoforms on Division of Epithelial Cells

Biochemistry (Moscow) ◽

10.1134/s0006297920090072 ◽

2020 ◽

Vol 85 (9) ◽

pp. 1072-1081

Author(s):

G. S. Shagieva ◽

I. B. Alieva ◽

C. Chaponnier ◽

V. B. Dugina

Keyword(s):

Epithelial Cells ◽

Actin Isoforms

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Cardiac and Skeletal Actin Substrates Uniquely Tune Cardiac Myosin Strain-Dependent Mechanics

10.1101/348920 ◽

2018 ◽

Cited By ~ 1

Author(s):

Yihua Wang ◽

Katalin Ajtai ◽

Thomas P. Burghardt

Keyword(s):

Resistive Load ◽

Step Size ◽

Actin Isoforms ◽

Cardiac Actin ◽

N Terminus ◽

Human Adults ◽

Force Velocity ◽

Strain Dependent

ABSTRACTNative cardiac ventricular myosin (βmys) translates actin under load by transducing ATP free energy into mechanical work on actin during muscle contraction. Unitary βmys translation of actin is the myosin step-size. In vitro and in vivo βmys regulates contractile force and velocity by remixing 3 different step-sizes with stepping frequencies autonomously adapted to workload. Cardiac and skeletal actin isoforms have a specific 1:4 stoichiometry in normal adult human ventriculum. Human adults with inheritable hypertrophic cardiomyopathy (HCM) up-regulate skeletal actin in ventriculum suggesting that increasing skeletal/cardiac actin stoichiometry also adapts myosin force-velocity to respond to the muscle’s inability to meet demand.Nanometer scale displacement of quantum dot (Qdot) labeled actin under resistive load when impelled by βmys measures single myosin force-velocity in vitro in the Qdot assay. Unitary displacement classification constraints introduced here better separates myosin based signal from background upgrading step-size spatial resolution to the sub-nanometer range. Single βmys force-velocity for skeletal vs cardiac actin substrates was compared using the Qdot assay.Two competing myosin strain-sensitive mechanisms regulate step-size choices dividing mechanical characteristics into low- and high-force regimes. The actin isoforms alter myosin strain-sensitive regulation such that onset of the high-force regime, where a short step-size is a large or major contributor, is offset to higher loads by a unique cardiac ELC N-terminus/cardiac-actin contact at Glu6/Ser358. It modifies βmys force-velocity by stabilizing the ELC N-terminus/cardiac-actin association. Uneven onset of the high-force regime for skeletal vs cardiac actin dynamically changes force-velocity characteristics as skeletal/cardiac actin fractional content increases in diseased muscle.

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