Calponin binds G‐actin and F‐actin with similar affinity

Ferjani, Imen; Fattoum, Abdellatif; Maciver, Sutherland K.; Manaï, Mohamed; Benyamin, Yves; Roustan, Claude

doi:10.1016/j.febslet.2006.07.065

Cited by 8 publications

(3 citation statements)

References 29 publications

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“…This reduction is larger than that previously observed with basic calponin and rabbit skeletal muscle actin (34), likely due to differences in protein concentrations. Although similar calponin/actin ratios were used, the higher protein concentrations used in this work would lead to more complete decoration of the actin filaments due to the concentration-dependent binding rate of calponin, consistent with previously reported dissociation constants of actin-calponin (50,51). However, it is also possible that the larger decrease in persistence length could arise from differences between actin isoforms.…”

Section: Discussionsupporting

confidence: 84%

“…for calponin and actin (51), the chosen molar ratios correspond to 80-90% decoration in both bulk and singlefilament experiments, with the higher molar ratio in the single-filament studies offsetting the lower overall protein concentration. This observed reduction in single-filament persistence length matches the prediction from bulk rheology, suggesting that the reduced persistence length is sufficient to explain the increases in g max and g crit within the framework of the previously proposed affine network model (30,33,52).…”

Section: Discussionmentioning

confidence: 99%

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Mechanism of Calponin Stabilization of Cross-Linked Actin Networks

Jensen

Morris

Gallant

et al. 2014

Biophysical Journal

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The actin-binding protein calponin has been previously implicated in actin cytoskeletal regulation and is thought to act as an actin stabilizer, but the mechanism of its function is poorly understood. To investigate this underlying physical mechanism, we studied an in vitro model system of cross-linked actin using bulk rheology. Networks with basic calponin exhibited a delayed onset of strain stiffening (10.0% without calponin, 14.9% with calponin) and were able to withstand a higher maximal strain before failing (35% without calponin, 56% with calponin). Using fluorescence microscopy to study the mechanics of single actin filaments, we found that calponin increased the flexibility of actin filaments, evident as a decrease in persistence length from 17.6 μm without to 7.7 μm with calponin. Our data are consistent with current models of affine strain behavior in semiflexible polymer networks, and suggest that calponin stabilization of actin networks can be explained purely by changes in single-filament mechanics. We propose a model in which calponin stabilizes actin networks against shear through a reduction of persistence length of individual filaments.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Mechanism of Calponin Stabilization of Cross-Linked Actin Networks

Jensen

Morris

Gallant

et al. 2014

Biophysical Journal

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“…Calponins are components of the smooth muscle thin filament that are suggested to regulate interactions between actin and myosin II. [ 8 ]…”

Section: Introductionmentioning

confidence: 99%

Evaluation of myofibroblasts in oral squamous cell carcinoma using H1 calponin: An immunohistochemical study

Ganesan

Nirmal²,

Nassar³

et al. 2015

J Oral Maxillofac Pathol

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Background:Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral mucosa. Stromal myofibroblasts play an important role in tumor invasion and metastasis, due to its ability to modify the extracellular matrix. The purpose of this study was to evaluate and compare the presence of myofibroblasts in normal mucosa, early invasive carcinoma and different grades of OSCC.Materials and Methods:The study included the archival tissues of 18 OSCC of well, moderate and poorly differentiated grades, three early invasive carcinomas and five normal mucosa. Myofibroblasts were identified by immunohistochemical detection of h1 calponin.Results:The percentage and intensity of h1 calponin were examined and positive immunostaining was observed in the myofibroblasts of all SCCs and early invasive carcinomas; however, these cells did not stain in the normal epithelium specimens. The presence of myofibroblasts was significantly higher in invasive pattern of OSCCs compared to normal mucosa cases (P < 0.070). A significant difference was not observed between the different grades of OSCC (P ≤ 0.812).Conclusion:These findings show the presence of myofibroblasts in OSCC but not in normal mucosa, suggesting that the genetically altered epithelium (carcinomatous epithelium) may have an inductive effect on the adjacent stroma to produce myofibroblasts. Also transdifferentiation of myofibroblasts is induced somewhere in the invasive stage of SCC irrespective of the epithelial cell differentiation.

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