[Excitation-contraction coupling in skeletal, cardiac and smooth muscles. Changes of vascular smooth muscle in arterial hypertension].
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Animals↗
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Results for “Muscle, Smooth”
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[Spasmolytic effect of piperiodlate on the excised smooth muscles. especially on uterine smooth muscles under the influence of sex hormones].
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Acetylcholine↗
[Study of receptors of the digestive smooth muscle: value of isolated smooth muscle cells].
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Humans↗
Alterations in the expression of the beta-cytoplasmic and the gamma-smooth muscle actins in hypertrophied urinary bladder smooth muscle.
The obstruction of the bladder outlet induces a marked increase in bladder mass, and this is accompanied by reduced contractility of bladder smooth muscle and alteration in the cellular architecture. In this study, we show that the composition of various isoforms of actin, a major component of the contractile apparatus and the cytoskeletal structure of smooth muscle, is altered in response to the obstruction-induced bladder hypertrophy. Northern blot analysis of the total RNA isolated from hypertrophied urinary bladder muscle, using a cDNA probe specific for smooth muscle gamma-actin, shows over 200% increase in the gamma-actin mRNA. However, the estimate of the amount of actin from the 2D gel reveals only a 16% increase in gamma-actin, since the 2D gel electrophoresis does not distinguish gamma-smooth muscle actin from gamma-cytoplasmic actin. The bladder smooth muscle alpha-actin and the smooth muscle alpha-actin mRNA are not altered in response to the hypertrophy. The obstructed bladder also reveals a decrease in the beta-cytoplasmic actin (37%) and a concomitant diminution in the beta-cytoplasmic actin mRNA (29%). Hence, the composition of the actin isoforms in bladder smooth muscle is altered in response to the obstruction-induced hypertrophy. This alteration of the actin isoforms is observed at both the protein and mRNA levels.
Actins↗
Comparison of beta-adrenoceptors in single smooth muscle cells and in isolated smooth muscle preparations from the guinea-pig taenia caecum.
Single smooth muscle cells were prepared from guinea-pig taenia caecum. To study the beta-adrenoceptors in the single cells, we observed mechanical responses of the single cells to beta-adrenergic drugs and also tested the binding of a [3H]-labelled drug to the single cells. The single cells showed a graded relaxing response to isoprenaline. The concentration-response curve was shifted in a parallel fashion by propranolol, indicating a competitive antagonism. The pA2 value of propranolol was in agreement with that estimated using the intact tissue. The dissociation constant of [3H]-dihydroalprenolol was similar to the value estimated in the microsomal fractions. The apparent dissociation constants of isoprenaline and propranolol estimated from inhibition of the specific binding of [3H]-dihydroalprenolol to the single cells were also in agreement with the values in the microsomal fractions. The results suggest that there is no change in the beta-adrenoceptor mechanism in single smooth muscle cells by isolating the cells.
Animals↗
Mitochondria as a feature of smooth muscle differentiation: a study of 70 smooth muscle tumors.
We report that the presence of numerous mitochondria is an ultrastructural feature of smooth muscle neoplasms which is diagnostically useful as a marker for smooth muscle differentiation. The number of mitochondria, as well as the usual features of smooth muscle differentiation, were studied in 70 smooth muscle neoplasms from a variety of body sites. The tumors were sub-classified according to the number of mitochondria (in the majority of the tumor cells) as sparse, moderate, abundant or packed. Thirty-one percent of the leiomyomas had sparse mitochondria and 69% had a moderate number of mitochondria. Seven percent of the leiomyoblastomas contained a moderate number of mitochondria, 33% contained abundant mitochondria and 60% were packed with mitochondria. Twelve percent of the leiomyosarcomas showed sparse mitochondria, 67% showed a moderate number of mitochondria, and 21% had abundant mitochondria. For the above tumor types, the cells with abundant and packed mitochondria contained few or no visible filaments, and these cells were often round or polygonal. By contrast, adjacent spindle cells often contained numerous filaments including dense bodies. The recognition of mitochondria as a feature of smooth muscle differentiation is diagnostically useful in tumor samples showing numerous mitochondria and a paucity of filaments and dense bodies.
Biomarkers, Tumor↗
Correlation between the distribution of smooth muscle or non muscle myosins and alpha-smooth muscle actin in normal and pathological soft tissues.
The distribution of smooth muscle (SM) and non muscle myosins was compared with that of alpha-SM actin in various normal and pathological tissues and in cultured cells by means of indirect immunofluorescence using a monoclonal antibody specific for alpha-SM actin [anti-alpha sm-1, Skalli et al., 1986b] and two polyclonal antibodies raised against bovine aortic myosin (ABAM) and human platelet myosin (AHPM), respectively. In normal tissues ABAM stained vascular and parenchymal smooth muscle cells (SMC), myoepithelial cells and myoid cells of the testis in a pattern similar to that reported by other authors with antisera raised against non vascular SM myosin. Cells stained with ABAM were always positive for anti-alpha sm-1. In human and experimental atheromatous plaques, most cells were positive for AHPM; a variable proportion was also stained for ABAM plus anti-alpha sm-1. Myofibroblasts from rat granulation tissue, Dupuytren's nodule and stroma from breast carcinoma were constantly positive for AHPM and negative for ABAM; however, myofibroblasts from Dupuytren's nodule and breast carcinoma were anti-alpha sm-1 positive. Early primary cultures of rat aortic SMC were positive for ABAM and anti-alpha sm-1 and became negative for ABAM and positive for AHPM after a few days in culture. They remained positive for AHPM and anti-alpha sm-1 after passages; the staining of AHPM and anti-alpha sm-1 appeared to be colocalized along the same stress fibers. These results may be relevant for the understanding of SMC function and adaptation, and show that in non malignant SMC proliferation, alpha-SM actin represents a more general marker of SM origin than SM myosin.
Actins↗
Energy turnover and mechanical properties of smooth muscle. With observations on vascular smooth muscle structure and function in the hypertensive rat.
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Adenosine Triphosphate↗
c-Myc gene single-strand binding protein-1, MSSP-1, suppresses transcription of alpha-smooth muscle actin gene in chicken visceral smooth muscle cells.
The expression of alpha-smooth muscle actin is coordinately regulated by positive and negative cis- elements in the promoter region. Although cis -elements and trans -acting factors involved in the positive regulation of the alpha-smooth muscle (alpha-SM) actin gene have been well characterized, details of negative regulation remain unclear. In functional analyses using cultured gizzard smooth muscle cells, we identified a sequence ranging from -238 to -219 in the promoter region as a novel negative element. Mutation and deletion analyses further revealed that a sequence, TATCTTA (-228 to -222), is essential for negative regulation. Gel shift assay and Southwestern blotting indicated that a nuclear protein factor specifically interacts with single- or double-strand DNA including this sequence, and the protein factor displays a highly potent binding to the sense strand DNA. cDNA cloning and gel shift analysis using anti-MSSP-1 antibodies revealed that this protein factor is a chicken homolog of human MSSP-1 (c- myc gene single-strand binding protein-1). In fact, overexpression of MSSP-1 in cultured smooth muscle cells suppresses the promoter activity. These results suggest a novel function of MSSP-1 regarding the transcriptional regulation of alpha-sm actin gene.
Actins↗
Expression of gamma -sarcoglycan in smooth muscle and its interaction with the smooth muscle sarcoglycan-sarcospan complex.
The sarcoglycan complex in striated muscle is a heterotetrameric unit integrally associated with sarcospan in the dystrophin-glycoprotein complex. The sarcoglycans, alpha, beta, gamma, and delta, are mutually dependent with regard to their localization at the sarcolemma, and mutations in any of the sarcoglycan genes lead to limb-girdle muscular dystrophies type 2C-2F. In smooth muscle beta- and delta-sarcoglycans are associated with epsilon-sarcoglycan, a glycoprotein homologous to alpha-sarcoglycan. Here, we demonstrate that gamma-sarcoglycan is also a component of the sarcoglycan complex in the smooth muscle. First, we show the presence of gamma-sarcoglycan in a number of smooth muscle-containing organs, and we verify the existence of identical transcripts in skeletal and smooth muscle. The specificity of the expression of gamma-sarcoglycan in smooth muscle was confirmed by analysis of smooth muscle cells in culture. Next, we provide evidence for the association of gamma-sarcoglycan with the sarcoglycan-sarcospan complex by biochemical analysis and comparison among animal models for muscular dystrophy. Moreover, we find disruption of the sarcoglycan complex in the vascular smooth muscle of a patient with gamma-sarcoglycanopathy. Taken together, our results prove that the sarcoglycan complex in vascular and visceral smooth muscle consists of epsilon-, beta-, gamma-, and delta-sarcoglycans and is associated with sarcospan.
Amino Acid Sequence↗
Heparin interactions with cultured human vascular endothelial and smooth muscle cells: incidence on vascular smooth muscle cell proliferation.
The binding, internalization, and metabolism of [3H]-heparin by human umbilical vein endothelial cells (HUVEC) and human umbilical arterial smooth muscle cells (HUASMC) have been characterized using size-exclusion HPLC. Incubation of HUVEC with [3H]-heparin demonstrated selective binding of high-molecular-weight (MW) components (MW = 21 kd), which was followed by rapid, temperature-dependent internalization. Over the next 3 hours, this internalized [3H]-heparin was degraded to low-MW fragments (MW = 0.9 kd). Primary cultures of HUASMC selectively bound extremely high-MW components (MW = 40 kd) and also smaller components whose MW (0.9 kd) corresponded to that of the heparin metabolite(s) formed by HUVEC. Subcultured HUASMC bound only the 40-kd components. Internalization of heparin by smooth muscle cells (SMC) was significantly slower than that determined for HUVEC, and even after 4 hours there was no evidence of the heparin being metabolized. However, when incubating primary rabbit aortic SMC with purified low-MW heparin fragment(s) produced in culture by HUVEC, a significantly lower proliferative response of these cells (IC50 = 18.4 micrograms/ml) was obtained. Virtually no effect was observed with subcultured SMC in the range of the tested concentrations (0-20 micrograms/ml). These fragments were 10- to 15-fold more effective in inhibiting primary SMC growth than was standard heparin. Furthermore, heparin fractions in the same range of molecular weights, purified either after nitrous acid or heparinase depolymerization of standard heparin, showed no activity on primary SMC growth, thus indicating a high degree of selectivity of the heparin metabolite(s) produced by HUVEC in culture.
Carrier Proteins↗
alpha-smooth-muscle actin and microvascular precursor smooth-muscle cells in pulmonary hypertension.
Little is known of the molecular basis of smooth-muscle cell development in the microvessels of the adult lung in pulmonary hypertension (PH). Using quantitative and immunogold electron microscopy techniques we report the development of microvascular precursor smooth-muscle cells (PSMCs) expressing alpha-smooth-muscle actin (alphaSMA), a first marker of smooth-muscle cell differentiation, in rats with hyperoxic PH. Increase in the frequency of distal (alveolar wall) vessels with alphaSMA cells preceded (Pchi2 < 0.02, Day 4) the increase in proximal (alveolar duct) vessels (Pchi2 < 0.02, Day 14). The smallest vessel with cells expressing alphaSMA (< 50 micrometer in diameter) increased most with time (Pchi2 < 0.001). Immunopositive PSMCs were rare in normal lung and frequent in hyperoxia. Well-developed filament arrays decorated with alphaSMA were detected in intermediate cells early in hyperoxia (Day 4). Similar filament networks were detected later in fibroblasts recruited to vessel walls (Days 7 to 14). By Day 28, cells derived from fibroblasts formed several layers in the vessel wall and expressed dense alphaSMA filament arrays, in either a central domain or mesh. Thus, intermediate cells are the source of cells expressing alphaSMA early in the microvessels in hyperoxic pulmonary hypertension and fibroblasts of cells in the late stage-the time of intense neomuscularization of the microvessels.
Actins↗
Molecular cloning of a novel phosphorylation-dependent inhibitory protein of protein phosphatase-1 (CPI17) in smooth muscle: its specific localization in smooth muscle.
The cDNA encoding a phosphorylation-dependent inhibitory protein of protein phosphatase-1 (PP1) was isolated from a porcine aorta library. The coding region represented the complete amino acid sequence of this protein comprised of a novel 147-residue polypeptide, which we termed CPI17, a 17-kDa PKC-potentiated inhibitory protein of PP1. As well as the native CPI17 from porcine aorta, the recombinant protein completely suppressed the PP1 activity (IC50 = 0.18 nM) by the stoichiometric thiophosphorylation. The CPI17 mRNA is expressed in smooth muscle tissues such as aorta and bladder, whereas little expression was observed in heart, skeletal muscle, and non-muscle tissues. These results suggest a specific regulatory mechanism of the PP1 activity through CPI17 in smooth muscle.
Amino Acid Sequence↗
Adenovirus-mediated transfer of the smooth muscle cell calponin gene inhibits proliferation of smooth muscle cells and fibroblasts.
Smooth muscle cell calponin (h1 or basic isoform) is an actin-binding protein that inhibits actomyosin MgATPase activity and is abundantly expressed in differentiated smooth muscle. Western blots showed bovine tracheal (BT) smooth muscle cells in culture expressed only 2 +/- 1% (n = 8) of the amount of calponin in tissues, while NIH-3T3 fibroblasts expressed none. We tested the hypothesis that introduction of calponin to cultured BT and 3T3 cells would inhibit cytoskeletal activities associated with cell proliferation. To achieve high-efficiency expression, an adenovirus encoding the CMV-calponin construct (Adv-CaP) was generated by homologous recombination in 293 cells. With greater than 90% of BT and 3T3 cells infected with Adv-CaP, calponin expression (32 and 11 microg/mg total protein, respectively) was similar to that in smooth muscle tissues (51 microg/mg). Cells were infected with Adv-CaP for 48 h, replated at low density and proliferation rates were assessed by cell density and [3H]thymidine incorporation. Cell growth and DNA synthesis by Adv-CaP-infected cells were inhibited to one-third control values for both BT and 3T3 cells. Expressed calponin was localized primarily on stress fibers in both cell types. Calponin may act at the cytoskeletal level to retard signaling pathways that normally lead to tight coupling between cell shape and DNA synthesis.
3T3 Cells↗
Age dependence of smooth muscle myosin expression by cultured rat aortic smooth muscle cells.
Vascular smooth muscle cells (SMC) in vivo are highly heterogeneous phenotypically, particularly during development and in the adult during periods of remodeling. Much remains to be learned, however, regarding regulation of the SMC phenotype at the gene level. Here, we studied smooth muscle myosin heavy chain (SMMHC) expression at the transcriptional and mRNA levels in SMC cultured from newborn, adult, and old animals, which express different patterns of differentiation markers. We also examined regulation of SMMHC gene expression by TGF-beta, a cytokine known to be involved in the differentiation process. The activity of SMMHC promoter constructs, the expression of which is smooth-muscle-specific, was greatest in SMC from newborn animals and least in cells from old animals. Thus, differences in the degree of differentiation of SMC from these three sources may at least in part be due to transcriptional events. SMC from the three animal sources each contained mRNAs for the SM-1A and SM-2A tail but not those for the SM-1B and SM-2B head isoforms. Total SMMHC mRNA levels reflected similar differences as found at the transcriptional level. SM-2A mRNA as a proportion of total SMMHC mRNA was greatest in SMC from newborn animals, consistent with their higher degree of differentiation. TGF-beta up-regulated both transcription and mRNA levels but did not change the proportions of SMMHC mRNAs. Though the levels of transcriptional activity and mRNA were widely different in untreated cells, the degree of TGF-beta stimulation was approximately the same in all cases.
Age Factors↗
A variant derived from rabbit aortic smooth muscle: phenotype modulation and restoration of smooth muscle characteristics in cells in culture.
We examined the relationship between growth arrest of smooth muscle cells and structural changes in microfilament bundles, and also that between the structural changes and the actions of contractile agonist using a multipassagable variant cell line (SM-3) derived from rabbit aortic smooth muscle cells. The content of smooth muscle type alpha-actin increased with density-dependent growth arrest of the SM-3 cells, but was attenuated in the logarithmically growing cultures. As assessed cytochemically, the growth-arrested cells contained longitudinally oriented bundles of actin-containing microfilament and myosin-based filaments visualized with rhodamine-phalloidin and antibody against myosin light chain 20, respectively, whereas both actin- and myosin-containing structures in logarithmically growing cells showed slight, shortened, or diffused patterns. Electron microscopic examination of the growth-arrested cells revealed that the cells contained numerous and conspicuous microfilament bundles associated with many compact electron-dense bodies. In addition, pinocytotic vesicles were often found near the plasma membrane in the growth-arrested cells. SM-3 cells in the growth-arrested phase responded to prostaglandin F2 alpha (3-30 microM) and rat endothelin (0.1-1.0 microM) with a reversible contractile response, in association with monophosphorylation and/or diphosphorylation of the myosin light chain 20. However, the influence of the contractile agonists was greatly reduced during logarithmic growth. These results suggest that in the SM-3 cells in the growth-arrested phase, there is a restoration of the contractile architecture and the myosin light chain phosphorylation system. Thus, this SM-3 cell line is expected to serve as a useful model for examining biochemical and physiological phenomena of smooth muscle.
Actins↗
Alpha-smooth muscle actin, a differentiation marker of smooth muscle cells, is present in microfilamentous bundles of pericytes.
alpha-Smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle cells (SMC) and present in high amounts in vascular SMC, was demonstrated in the cytoplasm of pericytes of various rat and human organs by means of immunocytochemistry at the electron microscopic level. In SMC and pericytes, alpha-sm actin was localized in microfilament bundles, strengthening the assumption that it is the functional isoform in these cell types and supporting the assumption that pericytes exert contractile functions.
Actin Cytoskeleton↗
The smooth muscle cell. III. Elastin synthesis in arterial smooth muscle cell culture.
Primate arterial smooth muscle cells and skin fibroblasts were examined for their ability to synthesize elastin in culture. In the presence of the lathyrogen beta-aminopropionitrile, the smooth muscle cells incorporate [3H]lysine into a lysyl oxidase substrate that was present in the medium and associated with the cell layer. A component having a mol wt of 72,000 and an electrophoretic mobility similar to that of authentic tropoelastin was isolated from the labeled smooth muscle cells by coacervation and fractionation with organic solvents. In the absence of beta-aminopropionitrile, long-term cultures of smooth muscle cells incorporated [14C]lysine into desmosine and isodesmosine, the cross-link amino acids unique to elastin. In contrast, no desmosine formation occurred in the fibroblast cultures. These characteristics demonstrate that arterial smooth muscle cells are capable of synthesizing both soluble and cross-lined elastin in culture.
Aminopropionitrile↗