Calponin repeats regulate actin filament stability and formation of podosomes in smooth muscle cells.
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TLDR
It is shown that actin fibers decorated with h1 CaP remain stable, whereas SM22 alpha-decorated actin bundles undergo rapid reorganization into podosomes within 30 min of PDBu exposure, which provides evidence for the existence of two functionally distinct actin filament populations.Abstract:
Phorbol ester induces actin cytoskeleton rearrangements in cultured vascular smooth muscle cells. Calponin and SM22 alpha are major components of differentiated smooth muscle and potential regulators of actin cytoskeleton interactions. Here we show that actin fibers decorated with h1 CaP remain stable, whereas SM22 alpha-decorated actin bundles undergo rapid reorganization into podosomes within 30 min of PDBu exposure. Ectopic expression of GFP alpha-actinin had no effect on the stability of the actin cytoskeleton and alpha-actinin was transported rapidly into PDBu-induced podosomes. Our results demonstrate the involvement of CaP and SM22 alpha in coordinating the balance between stabilization and dynamics of the actin cytoskeleton in mammalian smooth muscle. We provide evidence for the existence of two functionally distinct actin filament populations and introduce a molecular mechanism for the stabilization of the actin cytoskeleton by the unique actin-binding interface formed by calponin family-specific CLIK23 repeats.read more
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Podosomes: adhesion hot-spots of invasive cells.
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Functional plasticity of CH domains
TL;DR: Analysis of the actopaxin/parvin protein family suggests the existence of novel (type 4 and type 5) CH domain families which require special attention, as they appear to be a good example for how CH domains may function as scaffolds for other functional motifs of different properties.
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Tropomyosin inhibits ADF/cofilin-dependent actin filament dynamics.
Shoichiro Ono,Kanako Ono +1 more
TL;DR: Results suggest that tropomyosin is a physiological inhibitor of ADF/cofilin-dependent actin dynamics, and is implicated in stabilization of actin cytoskeleton.
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Smooth muscle specific expression of calponin
TL;DR: A differentiation‐linked increase in calponin expression in embryonic chick gizzard is demonstrated using a monoclonal antibody specific for avian calp onin, suggested as a potentially useful index of smooth muscle differentiation.
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An atomic model of actin filaments cross-linked by fimbrin and its implications for bundle assembly and function.
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