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Chen X, Li S, He L, Wang X, Liang P, Chen W, Bian M, Ren M, Lin J, Liang C, Xu J, Wu Z, Li X, Huang Y, Yu X. Molecular characterization of severin from Clonorchis sinensis excretory/secretory products and its potential anti-apoptotic role in hepatocarcinoma PLC cells. PLoS Negl Trop Dis 2013; 7:e2606. [PMID: 24367717 PMCID: PMC3868641 DOI: 10.1371/journal.pntd.0002606] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 10/28/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Clonorchiasis, caused by the infection of Clonorchis sinensis (C. sinensis), is a kind of neglected tropical disease, but it is highly related to cholangiocarcinoma and hepatocellular carcinoma (HCC). It has been well known that the excretory/secretory products of C. sinensis (CsESPs) play key roles in clonorchiasis associated carcinoma. From genome and transcriptome of C. sinensis, we identified one component of CsESPs, severin (Csseverin), which had three putative gelsolin domains. Its homologues are supposed to play a vital role in apoptosis resistance of tumour cell. METHODOLOGY/PRINCIPAL FINDINGS There was significant similarity in tertiary structures between human gelsolin and Csseverin by bioinformatics analysis. We identified that Csseverin expressed at life stage of adult worm, metacercaria and egg by the method of quantitative real-time PCR and western blotting. Csseverin distributed in vitellarium and intrauterine eggs of adult worm and tegument of metacercaria by immunofluorence assay. We obtained recombinant Csseverin (rCsseverin) and confirmed that rCsseverin could bind with calciumion in circular dichroism spectrum analysis. It was demonstrated that rCsseverin was of the capability of actin binding by gel overlay assay and immunocytochemistry. Both Annexin V/PI assay and mitochondrial membrane potential assay of human hepatocarcinoma cell line PLC showed apoptosis resistance after incubation with different concentrations of rCsseverin. Morphological analysis, apoptosis-associated changes of mitochondrial membrane potential and Annexin V/PI apoptosis assay showed that co-incubation of PLC cells with rCsseverin in vitro led to an inhibition of apoptosis induced by serum-starved for 24 h. CONCLUSIONS/SIGNIFICANCE Collectively, the molecular properties of Csseverin, a molecule of CsESPs, were characterized in our study. rCsseverin could cause obvious apoptotic inhibition in human HCC cell line. Csseverin might exacerbate the process of HCC patients combined with C. sinensis infection.
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Affiliation(s)
- Xueqing Chen
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Shan Li
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Lei He
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Xiaoyun Wang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Pei Liang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Wenjun Chen
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Meng Bian
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Mengyu Ren
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Jinsi Lin
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Chi Liang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Jin Xu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Xuerong Li
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Yan Huang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
| | - Xinbing Yu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, People′s Republic of China
- Key Laboratory of Tropical Diseases Control at Sun Yat-sen University, Ministry of Education, Guangzhou, People′s Republic of China
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Liou YM, Watanabe M, Yumoto M, Ishiwata S. Regulatory mechanism of smooth muscle contraction studied with gelsolin-treated strips of taenia caeci in guinea pig. Am J Physiol Cell Physiol 2009; 296:C1024-33. [DOI: 10.1152/ajpcell.00565.2008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The potential roles of the regulatory proteins actin, tropomyosin (Tm), and caldesmon (CaD), i.e., the components of the thin filament, in smooth muscle have been extensively studied in several types of smooth muscles. However, controversy remains on the putative physiological significance of these proteins. In this study, we intended to determine the functional roles of Tm and CaD in the regulation of smooth muscle contraction by using a reconstitution system of the thin filaments. At appropriate conditions, the thin (actin) filaments within skinned smooth muscle strips of taenia caeci in guinea pigs could be selectively removed by an actin-severing protein, gelsolin, without irreversible damage to the contractile apparatus, and then the thin filaments were reconstituted with purified components of thin filaments, i.e., actin, Tm, and CaD. We found that the structural remodeling of actin filaments or thin filaments was functionally linked to the Ca2+-induced force development and reduction in muscle cross-sectional area (CSA). That is, after the reconstitution of the gelsolin-treated skinned smooth muscle strips with pure actin, the Ca2+-dependent force development was partially restored, but the Ca2+-induced reduction in CSA occurred once. In contrast, the reconstitution with actin, followed by Tm and CaD, restored not only the force generation but also both its Ca2+sensitivity and the reversible Ca2+-dependent reduction in CSA. We confirmed that both removal of the thin filaments by gelsolin treatment and reconstitution of the actin (thin) filaments with Tm and CaD caused no significant changes in the level of myosin regulatory light chain phosphorylation. We thus conclude that Tm and CaD are necessary for the full regulation of smooth muscle contraction in addition to the other regulatory systems, including the myosin-linked one.
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Gerthoffer WT, Gunst SJ. Invited review: focal adhesion and small heat shock proteins in the regulation of actin remodeling and contractility in smooth muscle. J Appl Physiol (1985) 2001; 91:963-72. [PMID: 11457815 DOI: 10.1152/jappl.2001.91.2.963] [Citation(s) in RCA: 230] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Smooth muscle cells are able to adapt rapidly to chemical and mechanical signals impinging on the cell surface. It has been suggested that dynamic changes in the actin cytoskeleton contribute to the processes of contractile activation and mechanical adaptation in smooth muscle. In this review, evidence for functionally important changes in actin polymerization during smooth muscle contraction is summarized. The functions and regulation of proteins associated with "focal adhesion complexes" (membrane-associated dense plaques) in differentiated smooth muscle, including integrins, focal adhesion kinase (FAK), c-Src, paxillin, and the 27-kDa small heat shock protein (HSP27) are described. Integrins in smooth muscles are key elements of mechanotransduction pathways that communicate with and are regulated by focal adhesion proteins that include FAK, c-Src, and paxillin as well as proteins known to mediate cytoskeletal remodeling. Evidence that functions of FAK and c-Src protein kinases are closely intertwined is discussed as well as evidence that focal adhesion proteins mediate key signal transduction events that regulate actin remodeling and contraction. HSP27 is reviewed as a potentially significant effector protein that may regulate actin dynamics and cross-bridge function in response to activation of p21-activated kinase and the p38 mitogen-activated protein kinase signaling pathway by signaling pathways linked to integrin proteins. These signaling pathways are only part of a large number of yet to be defined pathways that mediate acute adaptive responses of the cytoskeleton in smooth muscle to environmental stimuli.
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Affiliation(s)
- W T Gerthoffer
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada 89557-9946, USA.
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Jones KA, Perkins WJ, Lorenz RR, Prakash YS, Sieck GC, Warner DO. F-actin stabilization increases tension cost during contraction of permeabilized airway smooth muscle in dogs. J Physiol 1999; 519 Pt 2:527-38. [PMID: 10457068 PMCID: PMC2269509 DOI: 10.1111/j.1469-7793.1999.0527m.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
1. Dynamic actin reorganization involving actin polymerization and depolymerization may play an important functional role in smooth muscle. 2. This study tested the hypothesis that F-actin stabilization by phalloidin increases tension cost (i.e. ATP hydrolysis rate per unit of isometric force) during Ca2+-induced activation of Triton X-100-permeabilized canine tracheal smooth muscle. 3. Adenosine 5'-triphosphate (ATP) hydrolysis rate was quantified using an enzyme-coupled NADH fluorometric technique, regulatory myosin light chain (rMLC) phosphorylation was measured by Western blot analysis, and maximum unloaded shortening velocity (Vmax) was estimated by interpolation of the force-velocity relationship to zero load during isotonic loading. 4. Maximal activation with 10 microM free Ca2+ induced sustained increases in isometric force, stiffness, and rMLC phosphorylation. However, the increase in ATP hydrolysis rate initially reached peak values, but then declined to steady-state levels above that of the unstimulated muscle. Thus, tension cost decreased throughout steady-state isometric force. 5. Following incubation of permeabilized strips with 50 microM phalloidin for 1 h, the increases in isometric force and stiffness were not sustained despite a sustained increase in rMLC phosphorylation. Also, after an initial decline, tension cost increased throughout activation. Phalloidin had no effect on Vmax during steady-state isometric force or on rMLC phosphorylation. 6. These findings suggest that dynamic reorganization of actin is necessary for optimal energy utilization during contraction of permeabilized airway smooth muscle.
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Affiliation(s)
- K A Jones
- Departments of Anesthesiology, and Physiology and Biophysics, Mayo Clinic and Mayo Foundation, Rochester, MN 55905, USA.
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Taggart MJ, Wray S. Hypoxia and smooth muscle function: key regulatory events during metabolic stress. J Physiol 1998; 509 ( Pt 2):315-25. [PMID: 9575282 PMCID: PMC2230985 DOI: 10.1111/j.1469-7793.1998.315bn.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/1998] [Accepted: 03/31/1998] [Indexed: 11/28/2022] Open
Abstract
Hypoxia rapidly reduces force in many smooth muscles and we review recent data that shed light on the mechanisms involved. As many regulated cellular processes are integrated to co-ordinate smooth muscle contractility, the processes responsible for decreased force output with altered metabolism are also likely to be many, acting in concert, rather than the actions of one altered parameter. Nevertheless the aim of this study is to elucidate the hierarchical series of events that contribute to reduced smooth muscle force production during altered metabolism. We conclude that in many phasic smooth muscles the decrease in force can be attributed to impaired electro-mechanical coupling whereby the Ca2+ transient is reduced. A direct effect of hypoxia on the Ca2+ channel may be of key importance. In tonic vascular smooth muscles KATP channels may also play a role in the integrated functional responses to hypoxia. There are also many examples of force being reduced, in tonically activated preparations, without a fall in steady-state Ca2+; indeed it usually increases. We examine the roles of altered [ATP], pH, myosin phosphorylation, inorganic phosphate and proteolytic activity on the [Ca2+]-force relationship during hypoxia. We find no defining force-inhibitory role for any one factor acting alone, and suggest that force most probably falls as a result of the combination of myriad factors.
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Affiliation(s)
- M J Taggart
- Physiology Department, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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Wright GL, Battistella-Patterson AS. Involvement of the cytoskeleton in calcium-dependent stress relaxation of rat aortic smooth muscle. J Muscle Res Cell Motil 1998; 19:405-14. [PMID: 9635283 DOI: 10.1023/a:1005301821628] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Rat aortic smooth muscle exhibits a remarkable capacity for stress relaxation, the release of tension following tissue stretch. Stress relaxation was markedly enhanced in contracted aortic rings compared with unstimulated tissue. The magnitude of stress relaxation in contracted aortic rings correlated well with the passive tension imposed on the tissue by stretching, but showed little relationship to changes in tissue length or to the level of tension developed in response to agonist stimulation prior to stretch. The enhancement of stress relaxation in precontracted tissue was not affected by intimal rubbing or treatment with L-NAME. By comparison, the removal of extracellular calcium markedly attenuated stress relaxation. In addition, the use of cytochalasin B to block actin polymerization inhibited stress relaxation, whereas colchicine, a drug used to cause microtubule disassembly, had no effect on the phenomenon. The results indicate that the enhanced stress relaxation in contracted tissue is a calcium-dependent process and is not due to passive tissue elastic properties. We suggest that stress relaxation may not involve cross-bridge formation but could be explained by the remodelling of a portion of the tension-bearing actin cytoskeleton.
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Affiliation(s)
- G L Wright
- Department of Physiology, Marshall University School of Medicine, Huntington, WV 25704, USA
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Abstract
Gelsolin, an actin-binding and severing protein present in many mammalian cells, was characterized in human testis. Although abundant in testicular extracts, gelsolin was not detected in purified spermatogenic cells by immunoblot analysis. Immunofluorescence studies of testis sections showed that gelsolin has two main localizations: peritubular cells and the seminiferous epithelium. In peritubular cells, gelsolin was present together with alpha-SM actin, in agreement with the myoid cell characteristics of these cells. In a large proportion of the tubules, gelsolin was found mainly, together with actin, in the apical part of the seminiferous epithelium. This localization of gelsolin also was observed in seminiferous tubules with a partial or complete absence of germinal cells, which evokes a presence of gelsolin at the apex of Sertoli cells. However, in normal testis, a complex pattern of gelsolin labeling was also present, mostly in the apical third of the epithelium, around cells or groups of cells, mainly spermatids, and, less frequently, in various other localizations from the apical to the basal part of the seminiferous epithelium. Taken together, these observations suggest that gelsolin may play different functions in the seminiferous epithelium: (1) regulation of the dynamic alterations of the actin cytoskeleton in the apical cytoplasm of Sertoli cells, and (2) modification of actin filaments assemblies in specific structures at germ cell-Sertoli cell contacts. Thereby, the actin-modulating properties of gelsolin are probably involved in reorganization of the seminiferous epithelium related to germ cell differentiation.
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Teubner A, Sobek-Klocke I, Hinssen H, Eichenlaub-Ritter U. Distribution of gelsolin in mouse ovary. Cell Tissue Res 1994; 276:535-44. [PMID: 8062342 DOI: 10.1007/bf00343950] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The distribution of gelsolin, a calcium-dependent actin-modulating protein, and the expression of the corresponding gene, have been characterized with respect to morphogenetic processes in mouse ovary. Substantial amounts of gelsolin have been detected in the ovary and uterus of the mouse by immunoblot analysis. The similar relative ratio of mRNA of alpha-smooth muscle actin (alpha-SM actin) and gelsolin in the two organs suggests that expression of these two genes is coordinated at the transcriptional level. Immunofluorescence has demonstrated gelsolin predominantly in three types of cells in the ovary: (1) cells of the theca externa and stroma, (2) endothelial cells lining blood vessels, and (3) cells of the superficial epithelium of ovary. In the smooth-muscle-like cells of the theca externa, gelsolin appears tightly associated with the microfilamentous cytoskeleton, which is also rich in alpha-SM actin. The presence of gelsolin in myoid cells suggests that this protein, possibly by modulation of the activity of the actomyosin ATPase, plays a critical role in contractile and morphogenetic processes, e.g., during growth and maturation of the follicle or during ovulation. In cells of the endothelium, intracellular gelsolin is associated with the F-actin cytoskeleton around the nucleus. The circumferential belt lining the lateral cell membranes in cells of the superficial epithelium at the ovarian surface is also rich in gelsolin. Our observations indicate that the function of gelsolin as a calcium- and phospholipid-dependent modulator of actin assemblies is pivotal for the regulation of the dynamic alterations of the actin cytoskeleton in the superficial epithelium when cells become attenuated and retract their microvilli during growth of the follicle.
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Affiliation(s)
- A Teubner
- Lehrstuhl für Mikrobiologie/Gentechnologie, Fakultät für Biologie, Universität Bielefeld, Germany
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Watanabe M, Takemori S, Yagi N. X-ray diffraction study on mammalian visceral smooth muscles in resting and activated states. J Muscle Res Cell Motil 1993; 14:469-75. [PMID: 8300843 DOI: 10.1007/bf00297209] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Structural changes of guinea pig taenia coli and rat anococcygeus muscle during contraction were studied by X-ray diffraction. The diffraction pattern of the taenia coli showed the 14.4-nm myosin reflection, the 5.9-nm actin layer-line and a diffuse equatorial peak at 1/11.4 nm-1. On application of carbachol, the muscle contracted and the intensity of the 14.4-nm reflection showed a concentration-dependent decrease: the maximum decrease was 24% at 2 x 10(-5) M. Such an intensity decrease was not observed in K-contracture (154 mM). The intensity of the 5.9-nm actin layer-line did not change appreciably on activation. The equatorial peak became broader during contraction. The 14.4-nm myosin reflection of the anococcygeus muscle was weak. Its intensity increased by 106% during contraction induced by 2 x 10(-5) M phenylephrine and by 75% during K-contracture. These results suggest that the number of myosin filaments may increase during contraction of rat anococcygeus muscle but not guinea pig taenia coli.
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Affiliation(s)
- M Watanabe
- Department of Physiology, Jikei University School of Medicine, Tokyo, Japan
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Gailly P, Gillis JM, Capony JP. Influence of Ca-activated brevin on the mechanical properties of skinned smooth muscle. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1993; 332:205-10; discussion 210-2. [PMID: 8109334 DOI: 10.1007/978-1-4615-2872-2_19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Solutions of purified brevin were applied to skinned thin bundles or isolated fibres of smooth muscle. This produced a sharp drop of isometric tension, an effect due to the severing effect of brevin on actin filaments, partially depleted from tropomyosin in skinned preparations. On skinned single fibres, brevin accelerates the speed of unloaded shortening. As no effect was detected on the myofibrillar ATPase turnover rate, brevin was thought to affect the viscosity of the cytoplasm. This was confirmed by analysis of the cytoplasm stiffness which decreased in the presence of brevin. It is proposed that Ca-activated brevin acts on actin-filamin gels, set in parallel to the contractile apparatus.
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Affiliation(s)
- P Gailly
- Department of Physiology, University of Louvain, Bruxelles, Belgium
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Boels PJ, Pfitzer G. Relaxant effect of phalloidin on Triton-skinned microvascular and other smooth muscle preparations. J Muscle Res Cell Motil 1992; 13:71-80. [PMID: 1313442 DOI: 10.1007/bf01738430] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Guinea pig mesenteric microarteries (diameter 60-100 microns), the main branch of the mesenteric artery and taenia coli were skinned with 1% Triton X-100 for 4 h at 4 degrees C. Microarteries, mounted for circumferential force measurement, developed maximal active force in response to elevation of the free Ca2+ (pCa = 4.52, in EGTA buffer) in the presence of ATP (7.5 mM) and calmodulin (0.1-0.3 microM). In these preparations, addition of phalloidin (1-100 microM) slowly (greater than 1 h) relaxed submaximal contractions (pCa greater than 4.52) in a dose-dependent manner. Relaxation was irreversible as, after phalloidin wash-out, subsequent active force to pCa = 4.52 was also reduced. By contrast, phalloidin preincubation and wash-out under relaxed conditions (pCa greater than 8) only reduced subsequent force to pCa = 4.52 on prolonged stimulation. The extent of phalloidin-induced relaxation was not dependent on free Ca2+ between pCa 6.40 and 4.52. Phalloidin-induced relaxation did not occur during rigor contractions (i.e. absence of ATP and Ca2+). These mechanical effects of phalloidin were accompanied by a decreased leak of actin out of the skinned preparations and by the prevention of guanidine extraction of actin from these preparations. Phalloidin did not inhibit the myosin light chain kinase or phosphatase activity isolated from these preparations. In addition, the relaxant effects were also noted in taenia coli and the main branch of the mesenteric artery but not in skinned porcine ventricular heart muscle. These experiments suggest the possible participation of actin filament dynamics on the maintenance of active force in Triton-skinned smooth muscle.
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MESH Headings
- Animals
- Colon/drug effects
- Colon/enzymology
- Colon/physiology
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Guinea Pigs
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/enzymology
- Mesenteric Arteries/physiology
- Microcirculation/physiology
- Muscle Relaxation/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/enzymology
- Muscle, Smooth/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/physiology
- Myosin-Light-Chain Kinase/metabolism
- Octoxynol
- Phalloidine/pharmacology
- Phosphoric Monoester Hydrolases/metabolism
- Polyethylene Glycols
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Affiliation(s)
- P J Boels
- II. Physiologisches Institut, Universität Heidelberg, Germany
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12
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Gailly P, Gillis JM, Capony JP. Complex stiffness of smooth muscle cytoplasm in the presence of Ca-activated brevin. J Muscle Res Cell Motil 1991; 12:333-9. [PMID: 1834694 DOI: 10.1007/bf01738588] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Brevin, an F-actin severing protein, regulates actin gel-sol transformation in a Ca(2+)-dependent way. Here, we tested its effect on the stiffness of the cytoplasm of skinned smooth muscle, in the absence of actin-myosin interaction (inhibited myosin ATPase). Complex stiffness was measured by imposing sinusoidal stretches and releases at different frequencies (1-50 Hz). In the presence of Ca-activated brevin, the stiffness decreased by about 30%, at all frequencies, from its initial values in Ca-free, relaxing solution. This decrease reflected a fall in both elasticity and viscosity of the cytoplasm. We propose that brevin specifically operates on an actin network in parallel with the contractile apparatus, e.g. on the actin-filamin gel.
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Affiliation(s)
- P Gailly
- Département de Physiologie, Université Catholique de Louvain, Bruxelles, Belgium
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