The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Robert J Schwartz - One of the best experts on this subject based on the ideXlab platform.
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whole animal knockout of smooth muscle Alpha Actin does not alter excisional wound healing or the fibroblast to myofibroblast transition
Wound Repair and Regeneration, 2013Co-Authors: James J Tomasek, Robert J Schwartz, Carol J Haaksma, Eric W HowardAbstract:The contractile phenotype and function of myofibroblasts have been proposed to play a critical role in wound closure. It has been hypothesized smooth muscle Alpha-Actin expressed in myofibroblasts is critical for their formation and function. We have used smooth muscle α-Actin-null mice to test this hypothesis. Full-thickness excisional wounds closed at a similar rate in smooth muscle α-Actin -null and wild type mice. In addition, fibroblasts in smooth muscle α-Actin-null granulation tissue when immunostained with a monoclonal antibody that recognizes all muscle Actin isoforms exhibited a myofibroblast-like distribution and a stress fiber-like pattern, demonstrating that these cells acquired the myofibroblast phenotype. Dermal fibroblasts from smooth muscle α-Actin-null and wild type mice formed stress fibers and supermature focal adhesions, and generated similar amounts of contractile force in response to transforming growth factor-β1. Smooth muscle γ-Actin and skeletal muscle Alpha-Actin were expressed in smooth muscle α-Actin-null myofibroblasts, as demonstrated by immunostaining, real-time PCR, and mass spectrometry. These results demonstrate that smooth muscle α-Actin is not necessary for myofibroblast formation and function and for wound closure, and that smooth muscle γ-Actin and skeletal muscle α-Actin may be able to functionally compensate for the lack of smooth muscle α-Actin in myofibroblasts.
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myoepithelial cell contraction and milk ejection are impaired in mammary glands of mice lacking smooth muscle Alpha Actin
Biology of Reproduction, 2011Co-Authors: Carol J Haaksma, Robert J Schwartz, James J TomasekAbstract:Mammary myoepithelial cells are specialized smooth musclelike epithelial cells that express the smooth muscle Actin isoform: smooth muscle Alpha-Actin (ACTA2). These cells contract in response to oxytocin to generate the contractile force required for milk ejection during lactation. It is believed that ACTA2 contributes to myoepithelial contractile force generation; however, this hypothesis has not been directly tested. To evaluate the contribution of ACTA2 to mammary myoepithelial cell contraction, Acta2 null mice were utilized and milk ejection and myoepithelial cell contractile force generation were evaluated. Pups suckling on Acta2 null dams had a significant reduction in weight gain starting immediately postbirth. Cross-fostering demonstrated the lactation defect is with the Acta2 null dams. Carmine alum whole mounts and conventional histology revealed no underlying structural defects in Acta2 null mammary glands that could account for the lactation defect. In addition, myoepithelial cell formation and organization appeared normal in Acta2 null lactating mammary glands as evaluated using an Acta2 promoter-GFP transgene or phalloidin staining to visualize myoepithelial cells. However, mammary myoepithelial cell contraction in response to oxytocin was significantly reduced in isolated Acta2 null lactating mammary glands and in in vivo studies using Acta2 null lactating dams. These results demonstrate that lack of ACTA2 expression impairs mammary myoepithelial cell contraction and milk ejection and suggests that ACTA2 expression in mammary myoepithelial cells has the functional consequence of enhancing contractile force generation required for milk ejection.
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recruitment of the tinman homolog nkx 2 5 by serum response factor activates cardiac Alpha Actin gene transcription
Molecular and Cellular Biology, 1996Co-Authors: Chingyi Chen, Robert J SchwartzAbstract:We recently showed that the cardiogenic homeodomain factor Nkx-2.5 served as a positive Acting accessory factor for serum response factor (SRF) and that together they provided strong transcriptional activation of the cardiac Alpha-Actin promoter, depending upon intact serum response elements (SREs) (C. Y. Chen, J. Croissant, M. Majesky, S. Topouz, T. McQuinn, M. J. Frankovsky, and R. J. Schwartz, Dev. Genet. 19:119-130, 1996). As shown here, Nkx-2.5 and SRF collaborated to activate the endogenous murine cardiac Alpha-Actin gene in 10T1/2 fibroblasts by a mechanism in which SRF recruited Nkx-2.5 to the Alpha-Actin promoter. Activation of a truncated promoter consisting of the proximal Alpha-Actin SRE1 occurred even when Nkx-2.5 DNA-binding activity was blocked by a point mutation in the third helix of its homeodomain. Investigation of protein-protein interactions showed that Nkx-2.5 was bound to SRF in the absence of DNA in soluble protein complexes retrieved from cardiac myocyte nuclei but could also be detected in coassociated binding complexes on the proximal SRE1. Recruitment of Nkx-2.5 to an SRE depended upon SRF DNA-binding activity and was blocked by the dominant negative SRFpm1 mutant, which allowed for dimerization of SRF monomers but prevented DNA binding. Interactive regions shared by Nkx-2.5 and SRF were mapped to N-terminal/helix I and helix II/helix III regions of the Nkx-2.5 homeodomain and to the N-terminal extension of the MADS box. Our study suggests that physical association between Nkx-2.5 and SRF is one way that cardiac specified genes are activated in cardiac cell lineages.
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regulation of skeletal Alpha Actin promoter in young chickens during hypertrophy caused by stretch overload
American Journal of Physiology-cell Physiology, 1995Co-Authors: James A Carson, Robert J Schwartz, Frank W Booth, M E Coleman, Craig S StumpAbstract:Anterior latissimus dorsi (ALD) muscles of 3-wk-old male chickens were injected with plasmids containing various lengths of the chicken skeletal Alpha-Actin promoter (ranging from -2,090 to -77 rel...
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transforming growth factor beta response elements of the skeletal Alpha Actin gene combinatorial action of serum response factor yy1 and the sv40 enhancer binding protein tef 1
Journal of Biological Chemistry, 1994Co-Authors: W R Maclellan, Robert J Schwartz, Michael D. SchneiderAbstract:Abstract Skeletal Alpha-Actin (SkA) is representative of the cardiac genes that are expressed at high levels in embryonic myocardium, down-regulated after birth, and reactivated by trophic signals including type beta-transforming growth factors (TGF beta). To investigate the molecular basis for cardiac-restricted and TGF beta-induced SkA transcription, we have undertaken a mutational analysis of the SkA promoter in ventricular myocytes, with emphasis on the role of three nominal serum response elements. Serum response factor (SRF) and the bifunctional factor YY1 are the predominant cardiac proteins contActing the proximal SRE (SRE1). Mutations of SRE1 that prevent recognition by SRF and YY1, or SRF alone, virtually abolish SkA transcription in both TGF beta- and vehicle-treated cells; mutation of distal SREs was ineffective. A mutation which selectively abrogates YY1 binding increases both basal and TGF beta-dependent expression, substantiating the predicted role of YY1 as an inhibitor of SRF effects. However, efficient SkA transcription requires combinatorial action of SRE1 with consensus sites for Sp1 and the SV40 enhancer-binding protein, TEF-1. As isolated motifs, either SRE1- or TEF-1-binding sites function as TGF beta response elements. Induction of the SkA promoter by TGF beta required SRF and TEF-1 in concert, unlike other pathways for TGF beta-dependent gene expression.
James A Carson - One of the best experts on this subject based on the ideXlab platform.
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SRF and TEF-1 control of chicken skeletal Alpha-Actin gene during slow-muscle hypertrophy.
The American journal of physiology, 1996Co-Authors: James A Carson, R J Schwartz, F W BoothAbstract:The purpose of this study was to delineate the Alpha-Actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of the anterior latissimus dorsi (ALD) muscle of young chickens by weighting one wing. Minimal promoter constructs were evaluated by direct injection into the ALD, which demonstrated that both serum response element 1 (SRE1) and the transcriptional enhancer factor 1 (TEF-1) elements were sufficient for increased expression during stretch overload. A mutated SRE1 prevented expression in both basal and stretched ALD muscles, whereas a mutated TEF-1 element reduced Actin promoter function in both control and stretched muscles. The serum response factor (SRF)-SRE1 binding complex demonstrated faster migration in mobility shift assays from day 3-and day 6-stretched ALD nuclear extracts relative to their control. TEF-1 binding was qualitatively increased in stretched extracts at day 3 but not day 6 of stretch overload. Skeletal Alpha-Actin mRNA accumulated from day 3 to day 6 of stretch overload. These data demonstrate that SRE1 is necessary and sufficient for stretch-overload responsiveness from the skeletal Alpha-Actin promoter and that the SRF-SRE1 binding complex migrates faster in stretched nuclear extracts of hypertrophied relative to control extracts from intact ALD muscles of chickens.
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srf and tef 1 control of chicken skeletal Alpha Actin gene during slow muscle hypertrophy
American Journal of Physiology-cell Physiology, 1996Co-Authors: James A Carson, R J Schwartz, Frank W BoothAbstract:The purpose of this study was to delineate the Alpha-Actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of th...
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regulation of skeletal Alpha Actin promoter in young chickens during hypertrophy caused by stretch overload
American Journal of Physiology-cell Physiology, 1995Co-Authors: James A Carson, Robert J Schwartz, Frank W Booth, M E Coleman, Craig S StumpAbstract:Anterior latissimus dorsi (ALD) muscles of 3-wk-old male chickens were injected with plasmids containing various lengths of the chicken skeletal Alpha-Actin promoter (ranging from -2,090 to -77 rel...
Frank W Booth - One of the best experts on this subject based on the ideXlab platform.
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srf and tef 1 control of chicken skeletal Alpha Actin gene during slow muscle hypertrophy
American Journal of Physiology-cell Physiology, 1996Co-Authors: James A Carson, R J Schwartz, Frank W BoothAbstract:The purpose of this study was to delineate the Alpha-Actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of th...
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regulation of skeletal Alpha Actin promoter in young chickens during hypertrophy caused by stretch overload
American Journal of Physiology-cell Physiology, 1995Co-Authors: James A Carson, Robert J Schwartz, Frank W Booth, M E Coleman, Craig S StumpAbstract:Anterior latissimus dorsi (ALD) muscles of 3-wk-old male chickens were injected with plasmids containing various lengths of the chicken skeletal Alpha-Actin promoter (ranging from -2,090 to -77 rel...
Michael D. Schneider - One of the best experts on this subject based on the ideXlab platform.
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transforming growth factor beta response elements of the skeletal Alpha Actin gene combinatorial action of serum response factor yy1 and the sv40 enhancer binding protein tef 1
Journal of Biological Chemistry, 1994Co-Authors: W R Maclellan, Robert J Schwartz, Michael D. SchneiderAbstract:Abstract Skeletal Alpha-Actin (SkA) is representative of the cardiac genes that are expressed at high levels in embryonic myocardium, down-regulated after birth, and reactivated by trophic signals including type beta-transforming growth factors (TGF beta). To investigate the molecular basis for cardiac-restricted and TGF beta-induced SkA transcription, we have undertaken a mutational analysis of the SkA promoter in ventricular myocytes, with emphasis on the role of three nominal serum response elements. Serum response factor (SRF) and the bifunctional factor YY1 are the predominant cardiac proteins contActing the proximal SRE (SRE1). Mutations of SRE1 that prevent recognition by SRF and YY1, or SRF alone, virtually abolish SkA transcription in both TGF beta- and vehicle-treated cells; mutation of distal SREs was ineffective. A mutation which selectively abrogates YY1 binding increases both basal and TGF beta-dependent expression, substantiating the predicted role of YY1 as an inhibitor of SRF effects. However, efficient SkA transcription requires combinatorial action of SRE1 with consensus sites for Sp1 and the SV40 enhancer-binding protein, TEF-1. As isolated motifs, either SRE1- or TEF-1-binding sites function as TGF beta response elements. Induction of the SkA promoter by TGF beta required SRF and TEF-1 in concert, unlike other pathways for TGF beta-dependent gene expression.
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The vascular smooth muscle Alpha-Actin gene is reactivated during cardiac hypertrophy provoked by load.
Journal of Clinical Investigation, 1991Co-Authors: F. M. Black, Robert J Schwartz, S E Packer, Thomas G. Parker, Lloyd H. Michael, Robert Roberts, Michael D. SchneiderAbstract:Abstract Cardiac hypertrophy triggered by mechanical load possesses features in common with growth factor signal transduction. A hemodynamic load provokes rapid expression of the growth factor-inducible nuclear oncogene, c-fos, and certain peptide growth factors specifically stimulate the "fetal" cardiac genes associated with hypertrophy, even in the absence of load. These include the gene encoding vascular smooth muscle Alpha-Actin, the earliest Alpha-Actin expressed during cardiac myogenesis; however, it is not known whether reactivation of the smooth muscle Alpha-Actin gene occurs in ventricular hypertrophy. We therefore investigated myocardial expression of the smooth muscle Alpha-Actin gene after hemodynamic overload. Smooth muscle Alpha-Actin mRNA was discernible 24 h after coarctation and was persistently expressed for up to 30 d. In hypertrophied hearts, the prevalence of smooth muscle Alpha-Actin gene induction was 0.909, versus 0.545 for skeletal muscle Alpha-Actin (P less than 0.05). Ventricular mass after 2 d or more of aortic constriction was more highly correlated with smooth muscle Alpha-Actin gene activation (r = 0.852; P = 0.0001) than with skeletal muscle Alpha-Actin (r = 0.532; P = 0.009); P less than 0.0005 for the difference in the correlation coefficients. Thus, smooth muscle Alpha-Actin is a molecular marker of the presence and extent of pressure-overload hypertrophy, whose correlation with cardiac growth at least equals that of skeletal Alpha-Actin. Induction of smooth muscle Alpha-Actin was delayed and sustained after aortic constriction, whereas the nuclear oncogenes c-jun and junB were expressed rapidly and transiently, providing potential dimerization partners for transcriptional control by c-fos.
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Differential regulation of skeletal Alpha-Actin transcription in cardiac muscle by two fibroblast growth factors.
Proceedings of the National Academy of Sciences of the United States of America, 1990Co-Authors: Thomas G. Parker, Robert J Schwartz, Lau Chow, Michael D. SchneiderAbstract:Abstract In cardiac muscle, acidic and basic fibroblast growth factors (aFGF and bFGF) regulate at least five genes in common (including Alpha and beta myosin heavy chains, atrial natriuretic factor, and the sarcoplasmic reticulum calcium ATPase), provoking a generalized "fetal" phenotype similar to events in pressure-overload hypertrophy; however, aFGF and bFGF differentially control the striated Alpha-Actins. bFGF stimulates and aFGF inhibits skeletal Alpha-Actin transcripts associated with the embryonic heart, whereas cardiac Alpha-Actin mRNA is inhibited by aFGF but not bFGF. To elucidate mechanisms for these selective and discordant actions of aFGF and bFGF on cardiac muscle, chicken skeletal and cardiac Alpha-Actin promoter-driven reporter genes were introduced into neonatal rat cardiac myocytes by electroporation. Skeletal Alpha-Actin transcription was selectively stimulated by bFGF, whereas the cardiac Alpha-Actin promoter was unaffected. In contrast, aFGF suppressed both transfected Alpha-Actin genes. The differential regulation of skeletal Alpha-Actin transcription was equivalent with either purified or recombinant FGFs and was observed with 5' flanking sequences from either nucleotide -202 or -2000 to nucleotide -11. Positive and negative modulation of Alpha-Actin transcription by growth factors corresponded accurately to the endogenous genes in all permutations studied. These investigations provide a model for reciprocal control of gene transcription by aFGF vs. bFGF.
R J Schwartz - One of the best experts on this subject based on the ideXlab platform.
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Decreased expression of smooth muscle Alpha-Actin results in decreased contractile function of the mouse bladder.
The Journal of urology, 2020Co-Authors: R A Zimmerman, R J Schwartz, J J Tomasek, J Mcrae, C J Haaksma, R L Cowan, A N Jones, B P KroppAbstract:Smooth muscle Alpha-Actin (SMAlphaA) is an important Actin isoform for functional contractility in the mouse bladder. Alterations in the expression of SMAlphaA have been associated with a variety of bladder pathological conditions. Recently, a SMAlphaA-null mouse was generated and differences in vascular tone and contractility were observed between wild-type and SMAlphaA-null mice suggesting alterations in function of vascular smooth muscle. We used SMAlphaA-null mice to explore the hypothesis that SMAlphaA is necessary for normal bladder function. Reverse transcriptase polymerase chain reaction, Western blotting and immunohistochemical staining were used to confirm the absence of SMAlphaA transcript and protein in the bladder of SMAlphaA-null mice. In vitro bladder contractility compared between bladder rings harvested from wild-type and SMAlphaA-null mice was determined by force measurement following electrical field stimulation (EFS), and exposure to chemical agonists and antagonists including KCl, carbachol, atropine and tetrodotoxin. Resulting force generation profiles for each tissue and agent were analyzed. There was no detectable SMAlphaA transcript and protein expression in the bladder of SMAlphaA-null mice. Nine wild-type and 9 SMAlphaA-null mice were used in the contractility study. Bladders from SMAlphaA-null mice generated significantly less force than wild-type mice in response to EFS after KCl. Similarly, bladders from SMAlphaA-null mice generated less force than wild-type mice in response to pretreatment EFS, and EFS after carbachol and atropine, although the difference was not significant. Surprisingly, the bladders in SMAlphaA-null mice appeared to function normally and showed no gross or histological abnormalities. SMAlphaA appears to be necessary for the bladder to be able to generate normal levels of contractile force. No functional deficits were observed in the bladders of these animals but no stress was placed on these bladders. To our knowledge this study represents the first report to demonstrate the importance of expression of SMAlphaA in force generation in the bladder.
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SRF and TEF-1 control of chicken skeletal Alpha-Actin gene during slow-muscle hypertrophy.
The American journal of physiology, 1996Co-Authors: James A Carson, R J Schwartz, F W BoothAbstract:The purpose of this study was to delineate the Alpha-Actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of the anterior latissimus dorsi (ALD) muscle of young chickens by weighting one wing. Minimal promoter constructs were evaluated by direct injection into the ALD, which demonstrated that both serum response element 1 (SRE1) and the transcriptional enhancer factor 1 (TEF-1) elements were sufficient for increased expression during stretch overload. A mutated SRE1 prevented expression in both basal and stretched ALD muscles, whereas a mutated TEF-1 element reduced Actin promoter function in both control and stretched muscles. The serum response factor (SRF)-SRE1 binding complex demonstrated faster migration in mobility shift assays from day 3-and day 6-stretched ALD nuclear extracts relative to their control. TEF-1 binding was qualitatively increased in stretched extracts at day 3 but not day 6 of stretch overload. Skeletal Alpha-Actin mRNA accumulated from day 3 to day 6 of stretch overload. These data demonstrate that SRE1 is necessary and sufficient for stretch-overload responsiveness from the skeletal Alpha-Actin promoter and that the SRF-SRE1 binding complex migrates faster in stretched nuclear extracts of hypertrophied relative to control extracts from intact ALD muscles of chickens.
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srf and tef 1 control of chicken skeletal Alpha Actin gene during slow muscle hypertrophy
American Journal of Physiology-cell Physiology, 1996Co-Authors: James A Carson, R J Schwartz, Frank W BoothAbstract:The purpose of this study was to delineate the Alpha-Actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of th...
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Regulation of skeletal Alpha-Actin promoter in young chickens during hypertrophy caused by stretch overload.
The American journal of physiology, 1995Co-Authors: J A Carson, F W Booth, R J Schwartz, M E Coleman, Craig S StumpAbstract:Anterior latissimus dorsi (ALD) muscles of 3-wk-old male chickens were injected with plasmids containing various lengths of the chicken skeletal Alpha-Actin promoter (ranging from -2,090 to -77 relative to the transcription start site) driving luciferase. Hypertrophy of the left ALD muscle was induced by attaching a weight (11% of body wt) to the left wing of each chicken, with the unweighted contralateral wing serving the control. Six days of stretch overload significantly increased muscle mass 110%. Luciferase activity from the -2,090 Actin-luciferase chimeric gene increased 127% compared with the contralateral control ALD muscle. Luciferase activities driven by the -424, -202, and -99 Actin promoters were 179, 134, and 378% higher, respectively, in the stretched ALD muscle than in the contralateral control ALD muscle. Luciferase activity from the -77 deletion construct was not different between stretched and control muscles. These data indicate that the gene region responding to stretch is downstream of -99 and imply, but do not conclusively prove, that the region between -99 and -77, which contains serum response element 1, contributes to the stretch-induced increase in skeletal Alpha-Actin promoter activity in the ALD muscle.
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Phased cis-Acting promoter elements interact at short distances to direct avian skeletal Alpha-Actin gene transcription.
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Lau Chow, M.e. Hogan, R J SchwartzAbstract:Abstract Recently, site-directed mutagenesis uncovered four positive cis-Acting elements in the 5' promoter region of the chicken skeletal Alpha-Actin gene that directs myogenic tissue-restricted expression. In this study, interactions between the four promoter sites were examined by means of a series of insertion mutations that increased the linker region between adjacent elements by roughly half or complete DNA helical turns. Unexpectedly, transcriptional activity for all three sets of linker mutants, as assayed with a chloramphenicol acetyltransferase reporter gene, was found to vary in a fashion resembling a damped sinusoid with a period of roughly 10 base pairs, where the sinusoidal maxima appeared when length was increased by half-integral number of helix turns. We present a model which states that in the undistorted wild-type 5' flanking sequence, linker domains position each of the four promoter sites on the helix face opposite that of its immediate neighbors; when any of the three linkers is increased by approximately a half-integral number of helix turns, pairs of neighboring promoter sites are brought into alignment. We propose that this is the required orientation for inducing skeletal muscle-specific promoter activity, achieved in the wild-type promoter as a result of protein-induced torsional deformation.
