- Email: [email protected]
The type III transforming growth factor beta receptor is required for coronary vessel development
418
ABSTRACTS / Developmental Biology 306 (2007) 411–426
tetralogy of Fallot. Conclusion: The most susceptible period in the rat at the toxicity by FA deficiency induced by MTX was in the 9th and 10th day and at dose of 0.25 and 0.5 mg/kg. The deficiency of FA is a risk factor for develop CHD. The proportion obtained for CHD was 16% and a ratio of 1:5. This study gives a useful model for damage mechanisms experimentation produces for FA deficit. doi:10.1016/j.ydbio.2007.03.645
Program/Abstract # 354 Regulation of the Snail family of transcription factors by the Notch and TGF-β pathways during heart development Kyle S. Niessen, YangXin Fu, Aly Karsan Department of Medical Biophysics, British Columbia Cancer Agency, Vancouver, BC, Canada Experimental Medicine Program, University of British Columbia, Vancouver, BC, Canada Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada The Notch and TGF-β signaling pathways have been shown to play important roles in regulating endothelial-to-mesenchymal transition (EMT). This process is required during cardiac cushion development and generates cells that contribute to the connective tissue of the valves and septa of the adult heart. We show that the Notch pathway, via CSL, directly binds and regulates expression of the Snail2 promoter in endothelial cells. We show that Snail2 is required for Notch mediated EMT, binds to and represses the VE-cadherin promoter, and induces a motile phenotype. While Notch does not directly regulate Snail1 expression, Notch and TGF-β act synergistically to regulate expression of Snail1 in endothelial cells. Additionally we demonstrate that Snail2 is expressed by the mesenchymal cells and a subset of endocardial cells of the atrioventricular canal and outflow tract during cardiac morphogenesis. Our data demonstrate that Snail2-deficient mouse embryos display defects in the initiation of cardiac cushion EMT at E9.5, which can be rescued by exogenous TGF-β2. Snail2-deficiency is compensated for by increased Snail1 expression after E9.5, restoring EMT and allowing cardiac cushion EMT. Collectively our data demonstrate that Notch signaling directly regulates Snail2, but not Snail1, expression and that the combined expression of Snail2 and Snail1 is required for cardiac cushion morphogenesis. doi:10.1016/j.ydbio.2007.03.646
Program/Abstract # 355 Shox2 is required for proper development of the murine cardiac pacemaker Ramon A. Espinoza-Lewis, Ling Yu, Yiping Chen Oral Biol. Dept., The Ohio State Univ., Columbus, OH, USA Cell and Mol. Biol. Dept., Tulane Univ. New Orleans, LA, USA
The heart beat, process by which a steady blood flow is achieved, is regulated by the pacemaker located within the sinus node. Several molecular markers have been used to characterize the sinus node. However, few genes so far described are involved in its differentiation. Targeted mutation in the Short stature homeobox gene 2 (Shox2) leads to cardiac edema and irregular heart beat. Shox2 is expressed in the venous-atrial junction (sinus node) beginning at E8.5, and the pattern remains through embryogenesis. By E10.5 the venous valves of the sinus node are forming and Shox2 expression extends to these regions, also comprising the cardiac pacemaker. Shox2 null mutation showed embryonic lethality around E11.5 and histological analysis demonstrated that it leads to the formation of hypoplastic venous valves, which likely results from a decreased level of cell proliferation. In situ hybridization showed a down-regulation of the pacemaker marker Hcn4, the conduction system marker Tbx3, and the gap junction protein Cx43 in the Shox2 mutant pacemaker region and venous valves. Accordingly, ANF, a direct Tbx3 downstream target is up-regulated. In contrast, the expression of the myogenic differentiation markers, MLC2a, MLC2v, and cTnt is not altered. Our results reveal an expression pattern of Shox2 in the developing heart, restricted to the sinus venosus region, including the pacemaker area. Histological analysis along with that of molecular markers indicates that Shox2 plays a critical role in the development and differentiation of pacemaker cardiomyocytes. Supported by an EIA grant from the AHA. doi:10.1016/j.ydbio.2007.03.647
Program/Abstract # 356 The type III transforming growth factor beta receptor is required for coronary vessel development Joey V. Barnett 1, Leigh A. Compton 1, Dru A. Potash 1, Christopher B. Brown 2 1 Dept. of Pharmacology, Vanderbilt University, Nashville, TN 2 Dept. of Pediatrics, Vanderbilt University, Nashville, TN Transforming Growth Factor Beta (TGFβ) Receptor III (TGFβR3) binds all 3 TGFβ ligands and inhibin with high affinity but lacks the serine/threonine kinase domain found in the Type I and Type II receptors (TGFβR1, TGFβR2). TGFβR3 facilitates signaling via TGFβR1/TGFβR2 but also plays a unique and nonredundant role in TGFβ signaling. 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 E14.5, the time when functional coronary vasculature is required for embryo viability. However, in null mice nascent coronary vessels attach to the aorta, form two coronary ostia, and initiate smooth muscle recruitment by E14. Analysis of earlier developmental stages revealed defects in the epicardium. At E13.5 these defects include an irregular and
ABSTRACTS / Developmental Biology 306 (2007) 411–426
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 AV 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. Source: HL67105(JVB), AHA0655129(JVB), and GM07347 (LAC). doi:10.1016/j.ydbio.2007.03.648
Program/Abstract # 357 Analysis of cardiovascular anomalies in the Ts65Dn mouse model for Down syndrome Austin D. Williams, Clara S. Moore Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
419
The most posterior section, the hindgut, forms by invagination of ectoderm, DNA endoreplication and convergent extension. The hindgut is subdivided into the small intestine, large intestine and rectum. The large intestine contains three morphologically and molecularly distinct cell populations. These are described as dorsal, ventral and boundary cells. The presence of guidance cues that lead migrating cells to their points of attachment has been shown in the CNS and somatic muscle systems in Drosophila. Specifically, the ECM protein, Slit, and Roundabout (Robo) family of receptors function in both systems to repel the migrating cells. Slit, Robo and Robo2 are also expressed in the hindgut. At this time in development, the cells of the hindgut have already been determined. Dorsal, ventral and boundary cells are correctly specified in slit loss of function mutants as shown by immunohistochemical stainings using cell-specific markers. Moreover, in slit loss of function mutants, lumen defects as well as defects in overall cell shape are seen using EM and immunohistochemistry. We suggest a novel role for Slit in lumen formation and cell shape regulation in the Drosophila hindgut. doi:10.1016/j.ydbio.2007.03.650
The Ts65Dn mouse is the most-studied murine model for Down syndrome (DS) or trisomy 21. Homology between triplicated murine genes and genes on human chromosome 21 (Hsa21) correlates with the shared anomalies of Ts65Dn mice and DS patients. Congenital heart defects occur in approximately 50 percent of DS individuals and we have worked to characterize cardiovascular anomalies observed in Ts65Dn neonates. Vascular abnormalities were identified in 17 percent of trisomic neonates by examination of gross anatomy. We found right aortic arch with Kommerell's diverticulum, interrupted aortic arch and persistent truncus arteriosis. Intracardiac defects were detected using staining with hemotoxylin and eosin, and Masson's trichrome. We have identified interventricular sepal defects and broad foramen ovale in trisomic neonates. Additionally, immunohistochemistry indicates abnormal muscle composition in the cardiac valves of trisomic neonates. These findings suggest that the gene imbalance in Ts65Dn disrupts crucial pathways in cardiac development. doi:10.1016/j.ydbio.2007.03.649
Program/Abstract # 358 Guidance molecules in organogenesis: Slit signaling in Drosophila hindgut development Nadine H. Soplop, Edgardo Santiago-Martínez, Sunita G. Kramer Pathology Department, University of Medicine and Dentistry of New Jersey at Robert Wood Johnson Medical School, Piscataway, NJ The alimentary canal in the Drosophila embryo is comprised of three regions, the foregut, midgut and hindgut.
Program/Abstract # 359 A non-canonical Wnt pathway mediated by Wnt5a is required for midgut elongation Sara Cervantes 1, Terry P. Yamaguchi 2, Matthias Hebrok 1 1 Diabetes Center, Dept. of Medicine, University of California San Francisco, San Francisco, CA, USA 2 Cancer and Developmental Biology Laboratory, Center for Cancer Research, NCI-Frederick, Frederick, MD, USA Several morphogenetic processes that occur during mouse development involve tissue elongation. At embryonic day 10.5, the midgut area of the gastrointestinal tract starts to elongate along the anterior-posterior axis forming a loop that will herniate outside the abdominal cavity around embryonic day 13.5. The scarcity of knowledge regarding the molecular and cellular basis of this morphogenetic process prompted us to identify the signaling pathways required for midgut elongation. Here, we show that Wnt5a, a non-canonical Wnt ligand, is expressed in the gut at the onset of midgut elongation in a restricted pattern. Mice deficient in Wnt5a show multiple malformations in the gastrointestinal tract including a dramatic shortening of the small intestine. Interestingly, the remaining intestinal tissue does not show any defects in differentiation by embryonic day 18.5. Closer inspection of the phenotype showed that instead of elongating and forming a ventral loop, the midgut forms a bifurcated lumen which grows parallel to the main branch. Additional results indicate that neither the Wnt/Planar Cell Polarity nor Wnt/β-catenin pathways are involved in Wnt5a function during midgut elongation. Our results demonstrate that Wnt5a is required for the elongation of thesmall intestine
ABSTRACTS / Developmental Biology 306 (2007) 411–426
tetralogy of Fallot. Conclusion: The most susceptible period in the rat at the toxicity by FA deficiency induced by MTX was in the 9th and 10th day and at dose of 0.25 and 0.5 mg/kg. The deficiency of FA is a risk factor for develop CHD. The proportion obtained for CHD was 16% and a ratio of 1:5. This study gives a useful model for damage mechanisms experimentation produces for FA deficit. doi:10.1016/j.ydbio.2007.03.645
Program/Abstract # 354 Regulation of the Snail family of transcription factors by the Notch and TGF-β pathways during heart development Kyle S. Niessen, YangXin Fu, Aly Karsan Department of Medical Biophysics, British Columbia Cancer Agency, Vancouver, BC, Canada Experimental Medicine Program, University of British Columbia, Vancouver, BC, Canada Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada The Notch and TGF-β signaling pathways have been shown to play important roles in regulating endothelial-to-mesenchymal transition (EMT). This process is required during cardiac cushion development and generates cells that contribute to the connective tissue of the valves and septa of the adult heart. We show that the Notch pathway, via CSL, directly binds and regulates expression of the Snail2 promoter in endothelial cells. We show that Snail2 is required for Notch mediated EMT, binds to and represses the VE-cadherin promoter, and induces a motile phenotype. While Notch does not directly regulate Snail1 expression, Notch and TGF-β act synergistically to regulate expression of Snail1 in endothelial cells. Additionally we demonstrate that Snail2 is expressed by the mesenchymal cells and a subset of endocardial cells of the atrioventricular canal and outflow tract during cardiac morphogenesis. Our data demonstrate that Snail2-deficient mouse embryos display defects in the initiation of cardiac cushion EMT at E9.5, which can be rescued by exogenous TGF-β2. Snail2-deficiency is compensated for by increased Snail1 expression after E9.5, restoring EMT and allowing cardiac cushion EMT. Collectively our data demonstrate that Notch signaling directly regulates Snail2, but not Snail1, expression and that the combined expression of Snail2 and Snail1 is required for cardiac cushion morphogenesis. doi:10.1016/j.ydbio.2007.03.646
Program/Abstract # 355 Shox2 is required for proper development of the murine cardiac pacemaker Ramon A. Espinoza-Lewis, Ling Yu, Yiping Chen Oral Biol. Dept., The Ohio State Univ., Columbus, OH, USA Cell and Mol. Biol. Dept., Tulane Univ. New Orleans, LA, USA
The heart beat, process by which a steady blood flow is achieved, is regulated by the pacemaker located within the sinus node. Several molecular markers have been used to characterize the sinus node. However, few genes so far described are involved in its differentiation. Targeted mutation in the Short stature homeobox gene 2 (Shox2) leads to cardiac edema and irregular heart beat. Shox2 is expressed in the venous-atrial junction (sinus node) beginning at E8.5, and the pattern remains through embryogenesis. By E10.5 the venous valves of the sinus node are forming and Shox2 expression extends to these regions, also comprising the cardiac pacemaker. Shox2 null mutation showed embryonic lethality around E11.5 and histological analysis demonstrated that it leads to the formation of hypoplastic venous valves, which likely results from a decreased level of cell proliferation. In situ hybridization showed a down-regulation of the pacemaker marker Hcn4, the conduction system marker Tbx3, and the gap junction protein Cx43 in the Shox2 mutant pacemaker region and venous valves. Accordingly, ANF, a direct Tbx3 downstream target is up-regulated. In contrast, the expression of the myogenic differentiation markers, MLC2a, MLC2v, and cTnt is not altered. Our results reveal an expression pattern of Shox2 in the developing heart, restricted to the sinus venosus region, including the pacemaker area. Histological analysis along with that of molecular markers indicates that Shox2 plays a critical role in the development and differentiation of pacemaker cardiomyocytes. Supported by an EIA grant from the AHA. doi:10.1016/j.ydbio.2007.03.647
Program/Abstract # 356 The type III transforming growth factor beta receptor is required for coronary vessel development Joey V. Barnett 1, Leigh A. Compton 1, Dru A. Potash 1, Christopher B. Brown 2 1 Dept. of Pharmacology, Vanderbilt University, Nashville, TN 2 Dept. of Pediatrics, Vanderbilt University, Nashville, TN Transforming Growth Factor Beta (TGFβ) Receptor III (TGFβR3) binds all 3 TGFβ ligands and inhibin with high affinity but lacks the serine/threonine kinase domain found in the Type I and Type II receptors (TGFβR1, TGFβR2). TGFβR3 facilitates signaling via TGFβR1/TGFβR2 but also plays a unique and nonredundant role in TGFβ signaling. 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 E14.5, the time when functional coronary vasculature is required for embryo viability. However, in null mice nascent coronary vessels attach to the aorta, form two coronary ostia, and initiate smooth muscle recruitment by E14. Analysis of earlier developmental stages revealed defects in the epicardium. At E13.5 these defects include an irregular and
ABSTRACTS / Developmental Biology 306 (2007) 411–426
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 AV 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. Source: HL67105(JVB), AHA0655129(JVB), and GM07347 (LAC). doi:10.1016/j.ydbio.2007.03.648
Program/Abstract # 357 Analysis of cardiovascular anomalies in the Ts65Dn mouse model for Down syndrome Austin D. Williams, Clara S. Moore Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
419
The most posterior section, the hindgut, forms by invagination of ectoderm, DNA endoreplication and convergent extension. The hindgut is subdivided into the small intestine, large intestine and rectum. The large intestine contains three morphologically and molecularly distinct cell populations. These are described as dorsal, ventral and boundary cells. The presence of guidance cues that lead migrating cells to their points of attachment has been shown in the CNS and somatic muscle systems in Drosophila. Specifically, the ECM protein, Slit, and Roundabout (Robo) family of receptors function in both systems to repel the migrating cells. Slit, Robo and Robo2 are also expressed in the hindgut. At this time in development, the cells of the hindgut have already been determined. Dorsal, ventral and boundary cells are correctly specified in slit loss of function mutants as shown by immunohistochemical stainings using cell-specific markers. Moreover, in slit loss of function mutants, lumen defects as well as defects in overall cell shape are seen using EM and immunohistochemistry. We suggest a novel role for Slit in lumen formation and cell shape regulation in the Drosophila hindgut. doi:10.1016/j.ydbio.2007.03.650
The Ts65Dn mouse is the most-studied murine model for Down syndrome (DS) or trisomy 21. Homology between triplicated murine genes and genes on human chromosome 21 (Hsa21) correlates with the shared anomalies of Ts65Dn mice and DS patients. Congenital heart defects occur in approximately 50 percent of DS individuals and we have worked to characterize cardiovascular anomalies observed in Ts65Dn neonates. Vascular abnormalities were identified in 17 percent of trisomic neonates by examination of gross anatomy. We found right aortic arch with Kommerell's diverticulum, interrupted aortic arch and persistent truncus arteriosis. Intracardiac defects were detected using staining with hemotoxylin and eosin, and Masson's trichrome. We have identified interventricular sepal defects and broad foramen ovale in trisomic neonates. Additionally, immunohistochemistry indicates abnormal muscle composition in the cardiac valves of trisomic neonates. These findings suggest that the gene imbalance in Ts65Dn disrupts crucial pathways in cardiac development. doi:10.1016/j.ydbio.2007.03.649
Program/Abstract # 358 Guidance molecules in organogenesis: Slit signaling in Drosophila hindgut development Nadine H. Soplop, Edgardo Santiago-Martínez, Sunita G. Kramer Pathology Department, University of Medicine and Dentistry of New Jersey at Robert Wood Johnson Medical School, Piscataway, NJ The alimentary canal in the Drosophila embryo is comprised of three regions, the foregut, midgut and hindgut.
Program/Abstract # 359 A non-canonical Wnt pathway mediated by Wnt5a is required for midgut elongation Sara Cervantes 1, Terry P. Yamaguchi 2, Matthias Hebrok 1 1 Diabetes Center, Dept. of Medicine, University of California San Francisco, San Francisco, CA, USA 2 Cancer and Developmental Biology Laboratory, Center for Cancer Research, NCI-Frederick, Frederick, MD, USA Several morphogenetic processes that occur during mouse development involve tissue elongation. At embryonic day 10.5, the midgut area of the gastrointestinal tract starts to elongate along the anterior-posterior axis forming a loop that will herniate outside the abdominal cavity around embryonic day 13.5. The scarcity of knowledge regarding the molecular and cellular basis of this morphogenetic process prompted us to identify the signaling pathways required for midgut elongation. Here, we show that Wnt5a, a non-canonical Wnt ligand, is expressed in the gut at the onset of midgut elongation in a restricted pattern. Mice deficient in Wnt5a show multiple malformations in the gastrointestinal tract including a dramatic shortening of the small intestine. Interestingly, the remaining intestinal tissue does not show any defects in differentiation by embryonic day 18.5. Closer inspection of the phenotype showed that instead of elongating and forming a ventral loop, the midgut forms a bifurcated lumen which grows parallel to the main branch. Additional results indicate that neither the Wnt/Planar Cell Polarity nor Wnt/β-catenin pathways are involved in Wnt5a function during midgut elongation. Our results demonstrate that Wnt5a is required for the elongation of thesmall intestine