The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Joey V Barnett - One of the best experts on this subject based on the ideXlab platform.
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BMP2 signals loss of epithelial character in epicardial cells but requires the Type III TGFβ receptor to promote invasion
Cellular Signalling, 2012Co-Authors: Cynthia R. Hill, Nora S. Sanchez, Julian A. Arrieta, Anita F. Austin, Charles C Hong, Christopher B. Brown, Joey V BarnettAbstract:Coronary Vessel development depends on a subpopulation of epicardial cells that undergo epithelial to mesenchymal transformation (EMT) and invade the subepicardial space and myocardium. These cells form the smooth muscle of the Vessels and fibroblasts, but the mechanisms that regulate these processes are poorly understood. Mice lacking the Type III Transforming Growth Factor β Receptor (TGFβR3) die by E14.5 due to failed Coronary Vessel development accompanied by reduced epicardial cell invasion. BMP2 signals via TGFβR3 emphasizing the importance of determining the relative contributions of the canonical BMP signaling pathway and TGFβR3-dependent signaling to BMP2 responsiveness. Here we examined the role of TGFβR3 in BMP2 signaling in epicardial cells. Whereas TGFβ induced loss of epithelial character and smooth muscle differentiation, BMP2 induced an ALK3-dependent loss of epithelial character and modestly inhibited TGFβ-stimulated differentiation. Tgfbr3−/− cells respond to BMP2 indicating that TGFβR3 is not required. However, Tgfbr3−/− cells show decreased invasion in response to BMP2 and overexpression of TGFβR3 in Tgfbr3−/− cells rescued invasion. Invasion was dependent on ALK5, ALK2, ALK3, and Smad4. Expression of TGFβR3 lacking the 3 C-terminal amino acids required to interact with the scaffolding protein GIPC (GAIP-interacting protein, C terminus) did not rescue. Knockdown of GIPC in Tgfbr3+/+ or Tgfbr3−/− cells rescued with TGFβR3 decreased BMP2-stimulated invasion confirming a requirement for TGFβR3/GIPC interaction. Our results reveal the relative roles of TGFβR3-dependent and TGFβR3-independent signaling in the actions of BMP2 on epicardial cell behavior and demonstrate the critical role of TGFβR3 in mediating BMP2-stimulated invasion.
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TGFβ and BMP-2 regulate epicardial cell invasion via TGFβR3 activation of the Par6/Smurf1/RhoA pathway
Cellular Signalling, 2011Co-Authors: Nora S. Sanchez, Joey V BarnettAbstract:Coronary Vessel development requires transfer of mesothelial cells to the heart surface to form the epicardium where some cells subsequently undergo epithelial–mesenchymal transformation (EMT) and invade the subepicardial matrix. Tgfbr3−/− mice die due to failed Coronary Vessel formation associated with decreased epicardial cell invasion but the mediators downstream of TGFβR3 are not well described. TGFβR3-dependent endocardial EMT stimulated by either TGFβ2 or BMP-2 requires activation of the Par6/Smurf1/RhoA 1pathway where Activin Receptor Like Kinase (ALK5) signals Par6 to act downstream of TGFβ to recruit Smurf1 to target RhoA for degradation to regulate apical-basal polarity and tight junction dissolution. Here we asked if this pathway was operant in epicardial cells and if TGFβR3 was required to access this pathway. Targeting of ALK5 in Tgfbr3+/+ cells inhibited loss of epithelial character and invasion. Overexpression of wild-type (wt) Par6, but not dominant negative (dn) Par6, induced EMT and invasion while targeting Par6 by siRNA inhibited EMT and invasion. Overexpression of Smurf1 and dnRhoA induced loss of epithelial character and invasion. Targeting of Smurf1 by siRNA or overexpression of constitutively active (ca) RhoA inhibited EMT and invasion. In Tgfbr3−/− epicardial cells which have a decreased ability to invade collagen gels in response to TGFβ2, overexpression of wtPar6, Smurf1, or dnRhoA had a diminished ability to induce invasion. Overexpression of TGFβR3 in Tgfbr3−/− cells, followed by siRNA targeting of Par6 or Smurf1, diminished the ability of TGFβR3 to rescue invasion demonstrating that the Par6/Smurf1/RhoA pathway is activated downstream of TGFβR3 in epicardial cells.
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The cytoplasmic domain of TGFβR3 through its interaction with the scaffolding protein, GIPC, directs epicardial cell behavior
Developmental Biology, 2011Co-Authors: Nora S. Sanchez, Cynthia R. Hill, Anita F. Austin, Jonathan H Soslow, Evisabel A. Craig, Christopher B. Brown, Todd D Camenisch, Andras Czirok, Joey V BarnettAbstract:Abstract The epicardium is a major contributor of the cells that are required for the formation of Coronary Vessels. Mice lacking both copies of the gene encoding the Type III Transforming Growth Factor β Receptor (TGFβR3) fail to form the Coronary vasculature, but the molecular mechanism by which TGFβR3 signals Coronary Vessel formation is unknown. We used intact embryos and epicardial cells from E11.5 mouse embryos to reveal the mechanisms by which TGFβR3 signals and regulates epicardial cell behavior. Analysis of E13.5 embryos reveals a lower rate of epicardial cell proliferation and decreased epicardially derived cell invasion in Tgfbr3 −/− hearts. Tgfbr3 −/− epicardial cells in vitro show decreased proliferation and decreased invasion in response to TGFβ1 and TGFβ2. Unexpectedly, loss of TGFβR3 also decreases responsiveness to two other important regulators of epicardial cell behavior, FGF2 and HMW-HA. Restoring full length TGFβR3 in Tgfbr3 −/− cells rescued deficits in invasion in vitro in response TGFβ1 and TGFβ2 as well as FGF2 and HMW-HA. Expression of TGFβR3 missing the 3 C-terminal amino acids that are required to interact with the scaffolding protein GIPC1 did not rescue any of the deficits. Overexpression of GIPC1 alone in Tgfbr3 −/− cells did not rescue invasion whereas knockdown of GIPC1 in Tgfbr3 +/+ cells decreased invasion in response to TGFβ2, FGF2, and HMW-HA. We conclude that TGFβR3 interaction with GIPC1 is critical for regulating invasion and growth factor responsiveness in epicardial cells and that dysregulation of epicardial cell proliferation and invasion contributes to failed Coronary Vessel development in Tgfbr3 −/− mice.
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Coronary Vessel Development Is Dependent on the Type III Transforming Growth Factor β Receptor
Circulation Research, 2007Co-Authors: Leigh A. Compton, Dru A. Potash, Christopher B. Brown, Joey V BarnettAbstract:Transforming growth factor (TGF) receptor III (TGFR3), or -glycan, binds all 3 TGF ligands and inhibin with high affinity but lacks the serine/threonine kinase domain found in the type I and type II receptors (TGFR1, TGFR2). TGFR3 facilitates signaling via TGFR1/TGFR2 but also has been suggested to play a unique and nonredundant role in TGF signaling. Targeted deletion of Tgfbr3 revealed a requirement for Tgfbr3 during development of the Coronary Vessels. Coronary vasculogenesis is significantly impaired in null mice, with few Vessels evident and numerous, persistent blood islands found throughout the epicardium. Tgfbr3-null mice die at embryonic day 14.5, the time when functional Coronary vasculature is required for embryo viability. However, in null mice nascent Coronary Vessels attach to the aorta, form 2 Coronary ostia, and initiate smooth muscle recruitment by embryonic day 14. Analysis of earlier developmental stages revealed defects in the epicardium. At embryonic day 13.5, these defects include an irregular and hypercellular epicardium with abundant subepicardial mesenchyme and a thin compact zone myocardium. Tgfbr3-null mice also displayed other defects in Coronary development, including dysmorphic and distended Vessels along the atrioventricular groove and subepicardial hemorrhage. In null mice, Vessels throughout the yolk sac and embryo form and recruit smooth muscle in a pattern indistinguishable from heterozygous or wild-type littermates. These data demonstrate a requirement for Tgfbr3 during Coronary Vessel development that is essential for embryonic viability. (Circ Res. 2007;101:784-791.)
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Coronary Vessel DevelopmentThe Epicardium Delivers
Trends in cardiovascular medicine, 2004Co-Authors: Harold E. Olivey, Leigh A. Compton, Joey V BarnettAbstract:Coronary artery disease accounts for 54% of all cardiovascular disease in the United States. Understanding how Coronary Vessels develop is likely to uncover novel drug targets and therapeutic strategies that will be useful in directing the repair or remodeling of Coronary Vessels in adults. Recent insights have identified the importance of cells derived from the proepicardium and epicardium in the formation of Coronary Vessels. This article reviews the basic steps in Coronary Vessel development, the molecules implicated in these steps, and the pressing questions awaiting answers.
Erik L. Ritman - One of the best experts on this subject based on the ideXlab platform.
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impact of Coronary vasa vasorum functional structure on Coronary Vessel wall perfusion distribution
American Journal of Physiology-heart and Circulatory Physiology, 2003Co-Authors: Mario Gössl, Nasser M. Malyar, Michael Rosol, Patricia E. Beighley, Erik L. RitmanAbstract:NonCoronary vasa vasorum have been described as networks of microVessels in the wall of arteries and veins. However, we have shown, using microcomputerized tomography (micro-CT) imaging methods, th...
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Impact of Coronary vasa vasorum functional structure on Coronary Vessel wall perfusion distribution
American journal of physiology. Heart and circulatory physiology, 2003Co-Authors: Mario Gössl, Nasser M. Malyar, Michael Rosol, Patricia E. Beighley, Erik L. RitmanAbstract:NonCoronary vasa vasorum have been described as networks of microVessels in the wall of arteries and veins. However, we have shown, using microcomputerized tomography (micro-CT) imaging methods, that porcine Coronary vasa vasorum have a tree-like branching structure similar to the vasculature in general. In this study, we elucidate functional aspects of Coronary vasa vasorum perfusion territories. Three pig hearts were injected with radiopaque Microfil via the Coronary sinus to fill the left anterior descending Coronary arteries (LADs) retrogradely at atmospheric pressure. In three other hearts, LADs were injected antegradely at 100-mmHg pressure via the left main carotid artery. Additionally, six LADs were injected in vivo with a suspension of 100- or 300-microm-diameter microspheres before harvesting of the hearts and injection of the LADs with Microfil. All harvested LADs were scanned intact with micro-CT (20 microm cubic voxels). The spatial density of vasa vasorum (no. of vasa/mm2) was measured in 20-microm-thick cross sections (at 0.4-mm intervals). Retrogradely injected LADs showed high and uniformly distributed vasa vasorum densities in the adventitia (means +/- SE; 5.38 +/- 0.09 vs. 3.58 +/- 0.1 vasa/mm2 in antegradely prepared LADs; P < 0.001). Antegradely prepared LADs showed patchy distributed, low-vasa-vasorum-density territories especially on the myocardial side of the Coronary artery wall (epicardial density: 4.29 +/- 0.13 vasa/mm2 vs. myocardial density: 2.80 +/- 0.1 vasa/mm2, P < 0.001). Microembolization reduced vasa vasorum densities significantly (100-mum-diameter microspheres: 3.26 +/- 0.07 vasa/mm2, P < 0.05; 300-microm-diameter microspheres: 2.66 +/- 0.07 vasa/mm2, P < 0.001 vs. antegrade controls) and increased the size of low-vasa-vasorum-density territories. We conclude that Coronary vasa vasorum are functional endarteries not connected via a plexus. This characteristic may have a significant impact on the spatial distribution of perfusion and drainage of the Coronary Vessel wall.
Mario Gössl - One of the best experts on this subject based on the ideXlab platform.
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prevention of vasa vasorum neovascularization attenuates early neointima formation in experimental hypercholesterolemia
Basic Research in Cardiology, 2009Co-Authors: Mario Gössl, Jorg Herrmann, Hui Tang, Daniele Versari, Offer Galili, Dallit Mannheim, Vincent S Rajkumar, Lilach O Lerman, Amir LermanAbstract:Vasa vasorum (VV) neovascularization is a key feature of early atherosclerosis and adds substantial endothelial exchange-surface to the Coronary Vessel wall. Thus, it is conceivable that VV neovascularization favors the entry of pro-inflammatory and pro-atherosclerotic blood components into the Coronary Vessel wall. We sought to investigate the effects of Thalidomide (Th), a potent anti-angiogenic drug on vasa vasorum (VV) neovascularization, Vessel wall inflammation, and neointima formation in early experimental atherosclerosis. Female domestic swine, 3 months old, were fed normal (N, n = 12) or high-cholesterol diet (HC, n = 12) for 3 months. In each group six pigs were randomized to 200 mg Thalidomide daily for the diet period (N + Th, HC + Th). LADs were scanned with micro-CT (20 μm cubic voxel size) to determine VV spatial density (#/mm²). Fresh-frozen Coronary tissue was used for western blotting (VEGF, TNF-α, LOX-1, Iκβα and Gro-α) and electrophoretic mobility shift assay (EMSA, NFκβ). Treatment with Thalidomide preserved VV spatial density [2.7 ± 0.3 (N), 6.4 ± 0.7 (HC), 3.5 ± 0.8 (HC + Th); p = ns HC + Th vs. N] and inhibited the expression of VEGF, TNF-α and LOX-1, but not NFκβ activity in the Coronary Vessel wall. Immunofluorescence analyses revealed co-localization of vWF but not SMA and NFκβ, TNF-α as well as VEGF in HC and HC + Th coronaries. Intima-media thickness was significantly inhibited in HC + Th compared to HC. Serum levels of hs-CRP and TNF-α did not differ among the groups. Our study supports a role of VV neovascularization in the development of and a therapeutic potential for anti-angiogenic intervention in early atherosclerosis.
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impact of Coronary vasa vasorum functional structure on Coronary Vessel wall perfusion distribution
American Journal of Physiology-heart and Circulatory Physiology, 2003Co-Authors: Mario Gössl, Nasser M. Malyar, Michael Rosol, Patricia E. Beighley, Erik L. RitmanAbstract:NonCoronary vasa vasorum have been described as networks of microVessels in the wall of arteries and veins. However, we have shown, using microcomputerized tomography (micro-CT) imaging methods, th...
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Impact of Coronary vasa vasorum functional structure on Coronary Vessel wall perfusion distribution
American journal of physiology. Heart and circulatory physiology, 2003Co-Authors: Mario Gössl, Nasser M. Malyar, Michael Rosol, Patricia E. Beighley, Erik L. RitmanAbstract:NonCoronary vasa vasorum have been described as networks of microVessels in the wall of arteries and veins. However, we have shown, using microcomputerized tomography (micro-CT) imaging methods, that porcine Coronary vasa vasorum have a tree-like branching structure similar to the vasculature in general. In this study, we elucidate functional aspects of Coronary vasa vasorum perfusion territories. Three pig hearts were injected with radiopaque Microfil via the Coronary sinus to fill the left anterior descending Coronary arteries (LADs) retrogradely at atmospheric pressure. In three other hearts, LADs were injected antegradely at 100-mmHg pressure via the left main carotid artery. Additionally, six LADs were injected in vivo with a suspension of 100- or 300-microm-diameter microspheres before harvesting of the hearts and injection of the LADs with Microfil. All harvested LADs were scanned intact with micro-CT (20 microm cubic voxels). The spatial density of vasa vasorum (no. of vasa/mm2) was measured in 20-microm-thick cross sections (at 0.4-mm intervals). Retrogradely injected LADs showed high and uniformly distributed vasa vasorum densities in the adventitia (means +/- SE; 5.38 +/- 0.09 vs. 3.58 +/- 0.1 vasa/mm2 in antegradely prepared LADs; P < 0.001). Antegradely prepared LADs showed patchy distributed, low-vasa-vasorum-density territories especially on the myocardial side of the Coronary artery wall (epicardial density: 4.29 +/- 0.13 vasa/mm2 vs. myocardial density: 2.80 +/- 0.1 vasa/mm2, P < 0.001). Microembolization reduced vasa vasorum densities significantly (100-mum-diameter microspheres: 3.26 +/- 0.07 vasa/mm2, P < 0.05; 300-microm-diameter microspheres: 2.66 +/- 0.07 vasa/mm2, P < 0.001 vs. antegrade controls) and increased the size of low-vasa-vasorum-density territories. We conclude that Coronary vasa vasorum are functional endarteries not connected via a plexus. This characteristic may have a significant impact on the spatial distribution of perfusion and drainage of the Coronary Vessel wall.
René M. Botnar - One of the best experts on this subject based on the ideXlab platform.
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highly efficient nonrigid motion corrected 3d whole heart Coronary Vessel wall imaging
Magnetic Resonance in Medicine, 2017Co-Authors: Gastao Cruz, René M. Botnar, David Atkinson, Markus Henningsson, Claudia PrietoAbstract:PURPOSE: To develop a respiratory motion correction framework to accelerate free-breathing three-dimensional (3D) whole-heart Coronary lumen and Coronary Vessel wall MRI. METHODS: We developed a 3D flow-independent approach for Vessel wall imaging based on the subtraction of data with and without T2-preparation prepulses acquired interleaved with image navigators. The proposed method corrects both datasets to the same respiratory position using beat-to-beat translation and bin-to-bin nonrigid corrections, producing coregistered, motion-corrected Coronary lumen and Coronary Vessel wall images. The proposed method was studied in 10 healthy subjects and was compared with beat-to-beat translational correction (TC) and no motion correction for the left and right Coronary arteries. Additionally, the Coronary lumen images were compared with a 6-mm diaphragmatic navigator gated and tracked scan. RESULTS: No significant differences (P > 0.01) were found between the proposed method and the gated and tracked scan for Coronary lumen, despite an average improvement in scan efficiency to 96% from 59%. Significant differences (P < 0.01) were found in right Coronary artery Vessel wall thickness, right Coronary artery Vessel wall sharpness, and Vessel wall visual score between the proposed method and TC. CONCLUSION: The feasibility of a highly efficient motion correction framework for simultaneous whole-heart Coronary lumen and Vessel wall has been demonstrated.
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Detection of Coronary plaques using MR Coronary Vessel wall imaging: validation of findings with intravascular ultrasound
European radiology, 2012Co-Authors: S.c. Gerretsen, Alfons G. H. Kessels, Patty J. Nelemans, Jouke Dijkstra, Johan H. C. Reiber, Rob J. Van Der Geest, Marcus Katoh, Johannes Waltenberger, Jos M. A. Van Engelshoven, René M. BotnarAbstract:Objectives Compared with X-ray Coronary angiography (CAG), magnetic resonance imaging of the Coronary Vessel wall (MR-CVW) may provide more information about plaque burden and Coronary remodelling. We compared MR-CVW with intravascular ultrasound (IVUS), the standard of reference for Coronary Vessel wall imaging, with regard to plaque detection and wall thickness measurements.
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MRI of Coronary Vessel walls using radial k-space sampling and steady-state free precession imaging.
American Journal of Roentgenology, 2006Co-Authors: Marcus Katoh, Matthias Stuber, Elmar Spuentrup, Arno Buecker, Tobias Schaeffter, Rolf W Günther, René M. BotnarAbstract:OBJECTIVE. The objective of our study was to investigate the impact of radial k-space sampling and steady-state free precession (SSFP) imaging on image quality in MRI of Coronary Vessel walls.SUBJECTS AND METHODS. Eleven subjects were examined on a 1.5-T MR system using three high-resolution navigator-gated and cardiac-triggered 3D black blood sequences (cartesian gradient-echo [GRE], radial GRE, and radial SSFP) with identical spatial resolution (0.9 × 0.9 × 2.4 mm3). The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), Vessel wall sharpness, and motion artifacts were analyzed.RESULTS. The mean SNR and CNR of the Coronary Vessel wall were improved using radial imaging and were best using radial k-space sampling combined with SSFP imaging. Vessel border definition was similar for all three sequences. Radial k-space sampling was found to be less sensitive to motion. Consistently good image quality was seen with the radial GRE sequence.CONCLUSION. Radial k-space sampling in MRI of Coronary Vessel...
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MRI of Coronary Vessel walls using radial k-space sampling and steady-state free precession imaging.
AJR. American journal of roentgenology, 2006Co-Authors: Marcus Katoh, Matthias Stuber, Elmar Spuentrup, Arno Buecker, Tobias Schaeffter, Rolf W Günther, René M. BotnarAbstract:The objective of our study was to investigate the impact of radial k-space sampling and steady-state free precession (SSFP) imaging on image quality in MRI of Coronary Vessel walls. Eleven subjects were examined on a 1.5-T MR system using three high-resolution navigator-gated and cardiac-triggered 3D black blood sequences (cartesian gradient-echo [GRE], radial GRE, and radial SSFP) with identical spatial resolution (0.9 x 0.9 x 2.4 mm3). The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), Vessel wall sharpness, and motion artifacts were analyzed. The mean SNR and CNR of the Coronary Vessel wall were improved using radial imaging and were best using radial k-space sampling combined with SSFP imaging. Vessel border definition was similar for all three sequences. Radial k-space sampling was found to be less sensitive to motion. Consistently good image quality was seen with the radial GRE sequence. Radial k-space sampling in MRI of Coronary Vessel walls resulted in fewer motion artifacts and improved SNR and CNR. The use of SSFP imaging, however, did not result in improved Coronary Vessel wall visualization.
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MR Coronary Vessel wall imaging: comparison between radial and spiral k-space sampling.
Journal of magnetic resonance imaging : JMRI, 2006Co-Authors: Marcus Katoh, Warren J Manning, Elmar Spuentrup, Arno Buecker, Rolf W Günther, René M. BotnarAbstract:PURPOSE: To compare radial and spiral k-space sampling in navigator-gated ECG-triggered three-dimensional (3D) Coronary Vessel wall imaging. MATERIALS AND METHODS: The right Coronary artery (RCA) Vessel walls of eight healthy subjects were imaged using a modified double-inversion prepulse in concert with radial and spiral data acquisition. For data analysis, two investigators blinded to the sequence parameters subjectively assessed image quality in terms of artifacts and Vessel wall visualization. Objective measures of the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and Vessel wall definition were also determined. RESULTS: Radial k-space sampling demonstrated fewer artifacts and led to improved visualization of the Coronary Vessel wall compared to spiral imaging (P< 0.05). This finding was also reflected in a better Vessel wall definition using radial data acquisition (P< 0.05). SNR and CNR were found to be higher when spiral k-space sampling was used (n.s.). CONCLUSION: Radial k-space sampling in concert with free-breathing navigator-gated cardiac-triggered MRI of the Coronary Vessel wall resulted in fewer motion artifacts and improved Vessel wall definition compared to spiral k-space sampling. The proposed approach therefore appears to be preferable.
Nora S. Sanchez - One of the best experts on this subject based on the ideXlab platform.
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BMP2 signals loss of epithelial character in epicardial cells but requires the Type III TGFβ receptor to promote invasion
Cellular Signalling, 2012Co-Authors: Cynthia R. Hill, Nora S. Sanchez, Julian A. Arrieta, Anita F. Austin, Charles C Hong, Christopher B. Brown, Joey V BarnettAbstract:Coronary Vessel development depends on a subpopulation of epicardial cells that undergo epithelial to mesenchymal transformation (EMT) and invade the subepicardial space and myocardium. These cells form the smooth muscle of the Vessels and fibroblasts, but the mechanisms that regulate these processes are poorly understood. Mice lacking the Type III Transforming Growth Factor β Receptor (TGFβR3) die by E14.5 due to failed Coronary Vessel development accompanied by reduced epicardial cell invasion. BMP2 signals via TGFβR3 emphasizing the importance of determining the relative contributions of the canonical BMP signaling pathway and TGFβR3-dependent signaling to BMP2 responsiveness. Here we examined the role of TGFβR3 in BMP2 signaling in epicardial cells. Whereas TGFβ induced loss of epithelial character and smooth muscle differentiation, BMP2 induced an ALK3-dependent loss of epithelial character and modestly inhibited TGFβ-stimulated differentiation. Tgfbr3−/− cells respond to BMP2 indicating that TGFβR3 is not required. However, Tgfbr3−/− cells show decreased invasion in response to BMP2 and overexpression of TGFβR3 in Tgfbr3−/− cells rescued invasion. Invasion was dependent on ALK5, ALK2, ALK3, and Smad4. Expression of TGFβR3 lacking the 3 C-terminal amino acids required to interact with the scaffolding protein GIPC (GAIP-interacting protein, C terminus) did not rescue. Knockdown of GIPC in Tgfbr3+/+ or Tgfbr3−/− cells rescued with TGFβR3 decreased BMP2-stimulated invasion confirming a requirement for TGFβR3/GIPC interaction. Our results reveal the relative roles of TGFβR3-dependent and TGFβR3-independent signaling in the actions of BMP2 on epicardial cell behavior and demonstrate the critical role of TGFβR3 in mediating BMP2-stimulated invasion.
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TGFβ and BMP-2 regulate epicardial cell invasion via TGFβR3 activation of the Par6/Smurf1/RhoA pathway
Cellular Signalling, 2011Co-Authors: Nora S. Sanchez, Joey V BarnettAbstract:Coronary Vessel development requires transfer of mesothelial cells to the heart surface to form the epicardium where some cells subsequently undergo epithelial–mesenchymal transformation (EMT) and invade the subepicardial matrix. Tgfbr3−/− mice die due to failed Coronary Vessel formation associated with decreased epicardial cell invasion but the mediators downstream of TGFβR3 are not well described. TGFβR3-dependent endocardial EMT stimulated by either TGFβ2 or BMP-2 requires activation of the Par6/Smurf1/RhoA 1pathway where Activin Receptor Like Kinase (ALK5) signals Par6 to act downstream of TGFβ to recruit Smurf1 to target RhoA for degradation to regulate apical-basal polarity and tight junction dissolution. Here we asked if this pathway was operant in epicardial cells and if TGFβR3 was required to access this pathway. Targeting of ALK5 in Tgfbr3+/+ cells inhibited loss of epithelial character and invasion. Overexpression of wild-type (wt) Par6, but not dominant negative (dn) Par6, induced EMT and invasion while targeting Par6 by siRNA inhibited EMT and invasion. Overexpression of Smurf1 and dnRhoA induced loss of epithelial character and invasion. Targeting of Smurf1 by siRNA or overexpression of constitutively active (ca) RhoA inhibited EMT and invasion. In Tgfbr3−/− epicardial cells which have a decreased ability to invade collagen gels in response to TGFβ2, overexpression of wtPar6, Smurf1, or dnRhoA had a diminished ability to induce invasion. Overexpression of TGFβR3 in Tgfbr3−/− cells, followed by siRNA targeting of Par6 or Smurf1, diminished the ability of TGFβR3 to rescue invasion demonstrating that the Par6/Smurf1/RhoA pathway is activated downstream of TGFβR3 in epicardial cells.
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The cytoplasmic domain of TGFβR3 through its interaction with the scaffolding protein, GIPC, directs epicardial cell behavior
Developmental Biology, 2011Co-Authors: Nora S. Sanchez, Cynthia R. Hill, Anita F. Austin, Jonathan H Soslow, Evisabel A. Craig, Christopher B. Brown, Todd D Camenisch, Andras Czirok, Joey V BarnettAbstract:Abstract The epicardium is a major contributor of the cells that are required for the formation of Coronary Vessels. Mice lacking both copies of the gene encoding the Type III Transforming Growth Factor β Receptor (TGFβR3) fail to form the Coronary vasculature, but the molecular mechanism by which TGFβR3 signals Coronary Vessel formation is unknown. We used intact embryos and epicardial cells from E11.5 mouse embryos to reveal the mechanisms by which TGFβR3 signals and regulates epicardial cell behavior. Analysis of E13.5 embryos reveals a lower rate of epicardial cell proliferation and decreased epicardially derived cell invasion in Tgfbr3 −/− hearts. Tgfbr3 −/− epicardial cells in vitro show decreased proliferation and decreased invasion in response to TGFβ1 and TGFβ2. Unexpectedly, loss of TGFβR3 also decreases responsiveness to two other important regulators of epicardial cell behavior, FGF2 and HMW-HA. Restoring full length TGFβR3 in Tgfbr3 −/− cells rescued deficits in invasion in vitro in response TGFβ1 and TGFβ2 as well as FGF2 and HMW-HA. Expression of TGFβR3 missing the 3 C-terminal amino acids that are required to interact with the scaffolding protein GIPC1 did not rescue any of the deficits. Overexpression of GIPC1 alone in Tgfbr3 −/− cells did not rescue invasion whereas knockdown of GIPC1 in Tgfbr3 +/+ cells decreased invasion in response to TGFβ2, FGF2, and HMW-HA. We conclude that TGFβR3 interaction with GIPC1 is critical for regulating invasion and growth factor responsiveness in epicardial cells and that dysregulation of epicardial cell proliferation and invasion contributes to failed Coronary Vessel development in Tgfbr3 −/− mice.
