scholarly journals CRP1, a LIM Domain Protein Implicated in Muscle Differentiation, Interacts with α-Actinin

1997 ◽  
Vol 139 (1) ◽  
pp. 157-168 ◽  
Author(s):  
Pascal Pomiès ◽  
Heather A. Louis ◽  
Mary C. Beckerle
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Cytoskeleton ◽  
Indirect Immunofluorescence ◽  
Muscle Cells ◽  
Muscle Differentiation ◽  
Full Length ◽  
Stress Fibers ◽  
Lim Domain

Members of the cysteine-rich protein (CRP) family are LIM domain proteins that have been implicated in muscle differentiation. One strategy for defining the mechanism by which CRPs potentiate myogenesis is to characterize the repertoire of CRP binding partners. In order to identify proteins that interact with CRP1, a prominent protein in fibroblasts and smooth muscle cells, we subjected an avian smooth muscle extract to affinity chromatography on a CRP1 column. A 100-kD protein bound to the CRP1 column and could be eluted with a high salt buffer; Western immunoblot analysis confirmed that the 100-kD protein is α-actinin. We have shown that the CRP1–α-actinin interaction is direct, specific, and saturable in both solution and solid-phase binding assays. The Kd for the CRP1–α-actinin interaction is 1.8 ± 0.3 μM. The results of the in vitro protein binding studies are supported by double-label indirect immunofluorescence experiments that demonstrate a colocalization of CRP1 and α-actinin along the actin stress fibers of CEF and smooth muscle cells. Moreover, we have shown that α-actinin coimmunoprecipitates with CRP1 from a detergent extract of smooth muscle cells. By in vitro domain mapping studies, we have determined that CRP1 associates with the 27-kD actin–binding domain of α-actinin. In reciprocal mapping studies, we showed that α-actinin interacts with CRP1-LIM1, a deletion fragment that contains the NH2-terminal 107 amino acids (aa) of CRP1. To determine whether the α-actinin binding domain of CRP1 would localize to the actin cytoskeleton in living cells, expression constructs encoding epitope-tagged full-length CRP1, CRP1-LIM1(aa 1-107), or CRP1-LIM2 (aa 108-192) were microinjected into cells. By indirect immunofluorescence, we have determined that full-length CRP1 and CRP1-LIM1 localize along the actin stress fibers whereas CRP1-LIM2 fails to associate with the cytoskeleton. Collectively these data demonstrate that the NH2-terminal part of CRP1 that contains the α-actinin–binding site is sufficient to localize CRP1 to the actin cytoskeleton. The association of CRP1 with α-actinin may be critical for its role in muscle differentiation.

scholarly journals Microvascular pericytes contain muscle and nonmuscle actins.

1985 ◽  
Vol 101 (1) ◽  
pp. 43-52 ◽  
Author(s):  
I M Herman ◽  
P A D'Amore
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Fluorescence Microscopy ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Stress Fibers ◽  
Fiber Bundles

We have affinity-fractionated rabbit antiactin immunoglobulins (IgG) into classes that bind preferentially to either muscle or nonmuscle actins. The pools of muscle- and nonmuscle-specific actin antibodies were used in conjunction with fluorescence microscopy to characterize the actin in vascular pericytes, endothelial cells (EC), and smooth muscle cells (SMC) in vitro and in situ. Nonmuscle-specific antiactin IgG stained the stress fibers of cultured EC and pericytes but did not stain the stress fibers of cultured SMC, although the cortical cytoplasm associated with the plasma membrane of SMC did react with nonmuscle-specific antiactin. Whereas the muscle-specific antiactin IgG failed to stain EC stress fibers and only faintly stained their cortical cytoplasm, these antibodies reacted strongly with the fiber bundles of cultured SMC and pericytes. Similar results were obtained in situ. The muscle-specific antiactin reacted strongly with the vascular SMC of arteries and arterioles as well as with the perivascular cells (pericytes) associated with capillaries and post-capillary venules. The non-muscle-specific antiactin stained the endothelium and the pericytes but did not react with SMC. These findings indicate that pericytes in culture and in situ possess both muscle and nonmuscle isoactins and support the hypothesis that the pericyte may represent the capillary and venular correlate of the SMC.

scholarly journals Human Full-Length Osteoprotegerin Induces the Proliferation of Rodent Vascular Smooth Muscle Cells both in vitro and in vivo

2010 ◽  
Vol 47 (3) ◽  
pp. 252-261 ◽  
Author(s):  
Riccardo Candido ◽  
Barbara Toffoli ◽  
Federica Corallini ◽  
Stella Bernardi ◽  
Davide Zella ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Full Length

Live dynamics of GFP-calponin: isoform-specific modulation of the actin cytoskeleton and autoregulation by C-terminal sequences

2000 ◽  
Vol 113 (21) ◽  
pp. 3725-3736 ◽  
Author(s):  
C. Danninger ◽  
M. Gimona
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Muscle Cells ◽  
Protein Kinase Inhibitors

The calponin family of F-actin-, tropomyosin- and calmodulin-binding proteins currently comprises three genetic variants. Their functional roles implicated from in vitro studies include the regulation of actomyosin interactions in smooth muscle cells (h1 calponin), cytoskeletal organisation in non-muscle cells (h2 calponin) and the control of neurite outgrowth (acidic calponin). We have now investigated the effects of calponin (CaP) isoforms and their C-terminal deletion mutants on the actin cytoskeleton by time lapse video microscopy of GFP fusion proteins in living smooth muscle cells and fibroblasts. It is shown that h1 CaP associates with the actin stress fibers in the more central part of the cell, whereas h2 CaP localizes to the ends of stress fibres and in the motile lamellipodial protrusions of spreading cells. Cells expressing h2 CaP spread more efficiently than those expressing h1 CaP and expression of GFP h1 CaP resulted in reduced cell motility in wound healing experiments. Notably, expression of GFP h1 CaP, but not GFP h2 CaP, conferred increased resistance of the actin cytoskeleton to the actin polymerization antagonists cytochalasin B and latrunculin B, as well as to the protein kinase inhibitors H7-dihydrochloride and rho-kinase inhibitor Y-27632. These data point towards a dual role of CaP in the stabilization and regulation of the actin cytoskeleton in vivo. Deletion studies further identify an autoregulatory role for the unique C-terminal tail sequences in the respective CaP isoforms.

scholarly journals Direct association of calponin with specific domains of PKC-α

2008 ◽  
Vol 295 (6) ◽  
pp. G1246-G1254 ◽  
Author(s):  
Sita Somara ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Binding Assay ◽  
Active Form ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Full Length ◽  
Direct Association

Calponin contributes to the regulation of smooth muscle contraction through its interaction with F-actin and inhibition of the actin-activated Mg-ATPase activity of phosphorylated myosin. Previous studies have shown that the contractile agonist acetylcholine induced a direct association of translocated calponin and PKC-α in the membrane. In the present study, we have determined the domain of PKC-α involved in direct association with calponin. In vitro binding assay was carried out by incubating glutathione S-transferase-calponin aa 92-229 with His-tagged proteins of individual domains and different combinations of domains of PKC-α. Calponin was found to bind directly to the full-length PKC-α. Calponin bound to C2 and C4 domains but not to C1 and C3 domains of PKC-α. When incubated with proteins of different combination of domains, calponin bound to C2-C3, C3-C4, and C2-C3-C4 but not to C1-C2 or C1-C2-C3. To determine whether these in vitro bindings mimic the in vivo associations, and in vivo binding assay was performed by transfecting colonic smooth muscle cells with His-tagged proteins of individual domains and different combinations of domains of PKC-α. Coimmunoprecipitation of calponin with His-tagged truncated forms of PKC-α showed that C1-C2, C1-C2-C3, C2-C3, and C3-C4 did not associate with calponin. Calponin associated only with full-length PKC-α and with C2-C3-C4 in cells in the resting state, and this association increased upon stimulation with acetylcholine. These data suggest that calponin bound to fragments that may mimic the active form of PKC-α and that the functional association of PKC-α with calponin requires both C2 and C4 domains during contraction of colonic smooth muscle cells.

Epicardial Cells of Human Adults Can Undergo an Epithelial-to-Mesenchymal Transition and Obtain Characteristics of Smooth Muscle Cells In Vitro

Stem Cells ◽  
2007 ◽  
Vol 25 (2) ◽  
pp. 271-278 ◽  
Author(s):  
John van Tuyn ◽  
Douwe E. Atsma ◽  
Elizabeth M. Winter ◽  
Ietje van der Velde-van Dijke ◽  
Daniel A. Pijnappels ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Epithelial To Mesenchymal Transition ◽  
Muscle Cells ◽  
Mesenchymal Transition ◽  
Epicardial Cells ◽  
Human Adults

Characterization and confocal imaging of calponin in gastrointestinal smooth muscle

1993 ◽  
Vol 265 (5) ◽  
pp. C1371-C1378 ◽  
Author(s):  
M. P. Walsh ◽  
J. D. Carmichael ◽  
G. J. Kargacin
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Thin Filament ◽  
Muscle Cells ◽  
Biochemical Properties ◽  
Confocal Imaging ◽  
Isolated Cells ◽  
Independent Manner

Calponin isolated from chicken gizzard smooth muscle binds in vitro to actin in a Ca(2+)-independent manner and thereby inhibits the actin-activated Mg(2+)-adenosinetriphosphatase of smooth muscle myosin. This inhibition is relieved when calponin is phosphorylated by protein kinase C or Ca2+/calmodulin-dependent protein kinase II, suggesting that calponin is involved in thin filament-associated regulation of smooth muscle contraction. To further examine this possibility, calponin was isolated from toad stomach smooth muscle, characterized biochemically, and localized in intact isolated cells. Toad stomach calponin had the same basic biochemical properties as calponin from other sources. Confocal immunofluorescence microscopy revealed that calponin in intact smooth muscle cells was localized to long filamentous structures that were colabeled by antibodies to actin or tropomyosin. Preservation of the basic biochemical properties of calponin from species to species suggests that these properties are relevant for its in vivo function. Its colocalization with actin and tropomyosin indicates that calponin is associated with the thin filament in intact smooth muscle cells.

Light and dark smooth muscle cells in estrogen-stimulated rat myometrium

1976 ◽  
Vol 54 (6) ◽  
pp. 822-833 ◽  
Author(s):  
R. E. Garfield ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Volume Control ◽  
Control Mechanisms ◽  
Dark Cells ◽  
Light Cells

Smooth muscle cells of different densities to transmission of electrons (termed light and dark cells) were found in rat myometrium examined in the electron microscope following fixation by immersion in glutaraldehyde. Light cells accounted for about 4% of the total population of cells. No light cells were found in tissues fixed in situ by intraarterial perfusion with glutaraldehyde. In addition to staining differences, light cells were distinguished from most dark cells by differences in nuclear, mitochondrial, endoplasmic reticular, and surface structures. The relative number of light and dark cells after in vitro fixation was not changed in tissues relaxed with adrenaline or contracted with oxytocin. Mechanical injury resulted in increased numbers of light cells. Similarly, chemical injury with metabolic inhibitors resulted in ATP depletion, followed by increased numbers of light cells and gain in water content. We concluded that light cells were produced by mechanical or metabolic damage, leading to loss of volume control mechanisms, swelling, and leakage of protein. Light cells found after fixation in vitro in numerous prior studies represent cells damaged during isolation, and not a physiological variant among smooth muscle cells.

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