The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Yuji Nakajima - One of the best experts on this subject based on the ideXlab platform.

  • rock1 expression is regulated by tgfβ3 and alk2 during valvuloseptal Endocardial Cushion formation
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2008
    Co-Authors: Masahide Sakabe, Toshiyuki Yamagishi, Hirokazu Sakata, Hiroko Matsui, Kazuo Ikeda, Yuji Nakajima
    Abstract:

    During early heart development at the looped heart stage, endothelial cells in the outflow tract and atrioventricular (AV) regions transform into mesenchyme to generate Endocardial Cushion tissue. This Endocardial epithelial–mesenchymal transition (EMT) is regulated by several regulatory pathways, including the transforming growth factor-beta (TGFβ), bone morphogenetic protein (BMP), and Rho-ROCK pathways. Here, we investigated the spatiotemporal expression pattern of ROCK1 mRNA during EMT in chick and examined whether TGFβ or BMP could induce the expression of ROCK1. At the onset of EMT, ROCK1 expression was up-regulated in endothelial/mesenchymal cells. A three-dimensional collagen gel assay was used to examine the mechanisms regulating the expression of ROCK1. In AV endocardium co-cultured with associated myocardium, ROCK1 expression was inhibited by either anti-TGFβ3 antibody, anti-ALK2 antibody or noggin, but not SB431542 (ALK5 inhibitor). In cultured preactivated AV endocardium, TGFβ3 protein induced the expression of ROCK1, but BMP did not. AV endothelial cells that were cultured in medium supplemented with TGFβ3 plus anti-ALK2 antibody failed to express ROCK1. These results suggest that the expression of ROCK1 is up-regulated at the onset of EMT and that signaling mediated by TGFβ3/ALK2 together with BMP is involved in the expression of ROCK1. Anat Rec, 291:845-857, 2008. © 2008 Wiley-Liss, Inc.

  • rho kinases regulate endothelial invasion and migration during valvuloseptal Endocardial Cushion tissue formation
    Developmental Dynamics, 2006
    Co-Authors: Masahide Sakabe, Toshiyuki Yamagishi, Kazuo Ikeda, Kazuki Nakatani, Norifumi Kawada, Kyoko Imanakayoshida, Toshimichi Yoshida, Yuji Nakajima
    Abstract:

    Rho-associated kinase (ROCK) is a downstream effector of small Rho-GTPases, and phosphorylates several substrates to regulate cell functions, including actin cytoskeletal reorganization and cellular motility. Endothelial–mesenchymal transformation (EMT) is a critical event in the formation of valves and septa during cardiogenesis. It has been reported that ROCK plays an important role in the regulation of Endocardial cell differentiation and migration during mouse cardiogenesis (Zhao and Rivkees [2004] Dev. Biol. 275:183–191). Immunohistochemistry showed that, during chick cardiogenesis, ROCK1 and -2 were expressed in the transforming and migrating endothelial/mesenchymal cells in the outflow tract (OT) and atrioventricular (AV) canal regions from which valvuloseptal Endocardial Cushion tissue would later develop. Treatment with Y27632, a specific ROCK inhibitor, of cultured AV explants or AV endothelial monolayers of stage 14-minus heart (preactivated stage for EMT) on three-dimensional collagen gel perturbed the seeding of mesenchymal cells into the gel lattice. In these experiments, Y27632 did not suppress the expression of an early transformation marker, smooth muscle α-actin. Moreover, Y27632 inhibited the mesenchymal invasion in stage 14–18 AV explants, in which endothelial cells had committed to undergo EMT. ML-9, a myosin light chain kinase inhibitor, also inhibited the mesenchymal invasion in cultured AV explants. These results suggest that ROCKs have a critical role in the mesenchymal cell invasion/migration that occurs at the late onset of EMT. Developmental Dynamics 235:94–104, 2006. © 2005 Wiley-Liss, Inc.

  • expression of bone morphogenetic protein 5 gene during chick heart development possible roles in valvuloseptal Endocardial Cushion formation
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2001
    Co-Authors: Toshiyuki Yamagishi, Yuji Nakajima, Katsumi Ando, Shinichiro Nishimatsu, Tsutomu Nohno, Hiroaki Nakamura
    Abstract:

    The bone morphogenetic protein (BMP) family, comprising multifunctional peptide growth factors, regulates many developmental processes in a variety of tissues. We examined the spatiotemporal expression of BMP5 by in situ hybridization in chick embryonic hearts from stages 5 to 33. The BMP5 gene was first expressed in the endoderm underlying the precardiac mesoderm at stages 5 to 8. Thereafter, BMP5 expression was restricted to the myocardium of the atrioventricular (AV) canal and outflow tract (OT) regions, where the valvuloseptal Endocardial Cushion tissue is induced. These results suggest that BMP5 may play important roles not only in myocardial differentiation, but also in the formation and maintenance of Endocardial Cushion tissue. Anat Rec 264:313–316, 2001. © 2001 Wiley-Liss, Inc.

  • mechanisms involved in valvuloseptal Endocardial Cushion formation in early cardiogenesis roles of transforming growth factor tgf β and bone morphogenetic protein bmp
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2000
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Shigeru Hokari, Hiroaki Nakamura
    Abstract:

    Endothelial-mesenchymal transformation (EMT) is a critical event in the generation of the Endocardial Cushion, the primordia of the valves and septa of the adult heart. This embryonic phenomenon occurs in the outflow tract (OT) and atrioventricular (AV) canal of the embryonic heart in a spatiotemporally restricted manner, and is initiated by putative myocardially derived inductive signals (adherons) which are transferred to the endocardium across the cardiac jelly. Abnormal development of Endocardial Cushion tissue is linked to many congenital heart diseases. At the onset of EMT in chick cardiogenesis, transforming growth factor (TGFβ)-3 is expressed in transforming endothelial and invading mesenchymal cells, while bone morphogenetic protein (BMP)-2 is expressed in the subjacent myocardium. Three-dimensional collagen gel culture experiments of the AV endocardium show that 1) myocardially derived inductive signals upregulate the expression of AV endothelial TGFβ3 at the onset of EMT, 2) TGFβ3 needs to be expressed by these endothelial cells to trigger the initial phenotypic changes of EMT, and 3) myocardial BMP2 acts synergistically with TGFβ3 in the initiation of EMT. Anat Rec 258:119–127, 2000. © 2000 Wiley-Liss, Inc.

  • expression of smooth muscle alpha actin in mesenchymal cells during formation of avian Endocardial Cushion tissue a role for transforming growth factor β3
    Developmental Dynamics, 1997
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Vladimir Mironov, Hiroaki Nakamura, Rachel R Markwald
    Abstract:

    During early cardiac morphogenesis, outflow tract (OT) and atrio-ventricular (AV) endothelial cells differentiate into mesenchymal cells, which have characteristics of smooth muscle-like myofibroblasts, and which form Endocardial Cushion tissue, the primordia of valves, and septa in the adult heart. During this embryonic event, transforming growth factor β3 (TGFβ3) is an essential element in the progression of endothelial-transformation into mesenchyme. TGFβs are known to be a potent inducer for mesodermal differentiation and a promoter for differentiation of endothelial cells into smooth muscle-like cells. Using a monoclonal antibody against smooth muscle-specific alpha-actin (SMA), we examined the immunohistochemical staining of this form of actin in avian Endocardial Cushion tissue formation. To determine whether TGFβ3 initiates the expression of SMA, the pre-migratory AV endothelial monolayer was cultured with or without chicken recombinant TGFβ3 and the expression of SMA was examined immunochemically. Migrating mesenchymal cells expressed SMA beneath the cell surface membrane. These cells showed a reduction of endothelial specific marker antigen, QH1. Stationary endothelial cells did not express SMA. The deposition of SMA in the mesenchymal tissue persisted until the end of the fetal period. Pre-migratory endothelial cells cultured in complete medium (CM199) that contained TGFβ3 expressed SMA, whereas cells cultured in CM199 alone did not. At the onset of the endothelial-mesenchymal transformation, migrating mesenchymal cells express SMA and the expression of this form of actin is upregulated by TGFβ3. The induction of the expression of SMA by TGFβ3 is one of the initial events in the cytoskeletal reorganization in endothelial cells which separate from one another during the initial phenotypic change associated with the endothelial-mesenchymal transformation. Dev. Dyn. 209:296–309, 1997. © 1997 Wiley-Liss, Inc.

Roger R. Markwald - One of the best experts on this subject based on the ideXlab platform.

  • the cspg2 gene disrupted in the hdf mutant is required for right cardiac chamber and Endocardial Cushion formation
    Developmental Biology, 1998
    Co-Authors: Corey H Mjaatvedt, Debi Turner, Hideshi Yamamura, Anthony A Capehart, Roger R. Markwald
    Abstract:

    Abstract The heart defect (hdf) mouse is a recessive lethal that arose from a transgene insertional mutation on chromosome 13. Embryos homozygous for the transgene diein uteroby embryonic day 10.5 postcoitus and exhibit specific defects along the anterior–posterior cardiac axis. The future right ventricle and conus/truncus of the single heart tube fail to form and the Endocardial Cushions in the atrioventricular and conus/truncus regions are absent. Because thehdfmouse mutation provided the opportunity to identify a gene required for Endocardial Cushion formation and for specification or maintenance of the anterior most segments of the heart, we initiated studies to further characterize the phenotype, clone the insertion site, and identify the gene disrupted. Chromosome mapping studies first identified the gene,Cspg2(versican), as a candidatehdfgene. In addition, an antibody recognizing a glycosaminoglycan epitope on versican was found to be positive by immunohistochemistry in the extracellular matrix of normal wild-type embryonic hearts, but absent in homozygous hearts. Expression analysis of theCspg2gene showed that the 6/8, 6/9, and 7/9Cspg2exon boundaries were present in mRNA of normal wild-type embryonic hearts but absent in the homozygous mutant embryos. DNA sequence flanking the transgene was used to isolate from a normal mouse library overlapping genomic DNA segments that span the transgene insertion site. The contiguous genomic DNA segment was found to contain exon 7 of theCspg2in a position 3′ to the transgene insertion site. These four separate lines of evidence support the hypothesis thatCspg2is the gene disrupted by the transgene insertion in thehdfmouse line. The findings of this study and our previous studies of thehdfinsertional mutant mouse have shown that normal expression of theCspg2gene is required for the successful development of the Endocardial Cushion swellings and the embryonic heart segments that give rise to the right ventricle and conus/truncus in the outlet of the looped heart.

  • identification of an autocrine signaling pathway that amplifies induction of Endocardial Cushion tissue in the avian heart
    Cells Tissues Organs, 1998
    Co-Authors: Ann F. Ramsdell, Yukiko Sugi, Ricardo A Morenorodriguez, M M Wienecke, Debi Turner, Corey H Mjaatvedt, Roger R. Markwald
    Abstract:

    Endocardial Cushion tissue is formed by an epithelial-mesenchymal transformation of Endocardial cells, a process which results from an inductive interaction between the myocardium and endocardium with

  • Induction of Endocardial Cushion tissue in the avian heart is regulated, in part, by TGFβ-3-mediated autocrine signaling
    Developmental biology, 1997
    Co-Authors: Ann F. Ramsdell, Roger R. Markwald
    Abstract:

    Abstract Valvuloseptal morphogenesis of the primitive heart tube into a four-chambered organ requires the formation of Endocardial Cushion tissue. The latter is the outcome of an inductive interaction in which Endocardial (endothelial) cells are induced to transform into mesenchyme by paracrine signals secreted by the adjacent myocardium. In this study, we propose that transforming endothelial/mesenchymal cells themselves secrete a factor—TGFβ-3—that functions in an autocrine mode to promote/sustain mesenchyme formation and possibly in a paracrine manner to amplify the original (myocardial) inductive event. Cushion mesenchyme-conditioned medium, previously demonstrated to be an endogenous source of autocrine, migration-promoting factors, was found in the present study to contain TGFβ-3, as detected by immunoblot analysis. Immunoneutralization of TGFβ-3 in preparations of Cushion mesenchyme-conditioned medium resulted in a failure of treated target Endocardial cells to migrate as mesenchyme, whereas inclusion of a control antibody did not inhibit the migration-promoting activity of the conditioned medium. Similar to treatment with the conditioned medium, direct addition of TGFβ-3 to target Endocardial cells also elicited invasive migration but only in cultures which had been activated in vivo by inductive interaction with the myocardium prior to treatment. Selective inhibition of TGFβ-3-mediated autocrine signaling in continuous cocultures of endocardium plus myocardium resulted in Endocardial cells which did not migrate, even though they had expressed early markers associated with Endocardial cell activation (e.g., α-smooth muscle actin, ES/130, and TGFβ-3). Collectively, these results suggest that (i) two signaling pathways, myocardial and Endocardial, are required to start and complete epithelial–mesenchymal transformation in Cushion-forming regions of the heart and (ii) the Endocardial pathway signals through iteration of TGFβ-3 and is not functionally redundant to the myocardial pathway.

  • expression of smooth muscle alpha actin in mesenchymal cells during formation of avian Endocardial Cushion tissue a role for transforming growth factor β3
    Developmental Dynamics, 1997
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Vladimir Mironov, Hiroaki Nakamura, Roger R. Markwald
    Abstract:

    During early cardiac morphogenesis, outflow tract (OT) and atrio-ventricular (AV) endothelial cells differentiate into mesenchymal cells, which have characteristics of smooth muscle-like myofibroblasts, and which form Endocardial Cushion tissue, the primordia of valves, and septa in the adult heart. During this embryonic event, transforming growth factor beta3 (TGF beta3) is an essential element in the progression of endothelial-transformation into mesenchyme. TGF beta(s) are known to be a potent inducer for mesodermal differentiation and a promoter for differentiation of endothelial cells into smooth muscle-like cells. Using a monoclonal antibody against smooth muscle-specific alpha-actin (SMA), we examined the immunohistochemical staining of this form of actin in avian Endocardial Cushion tissue formation. To determine whether TGF beta3 initiates the expression of SMA, the pre-migratory AV endothelial monolayer was cultured with or without chicken recombinant TGF beta3 and the expression of SMA was examined immunochemically. Migrating mesenchymal cells expressed SMA beneath the cell surface membrane. These cells showed a reduction of endothelial specific marker antigen, QH1. Stationary endothelial cells did not express SMA. The deposition of SMA in the mesenchymal tissue persisted until the end of the fetal period. Pre-migratory endothelial cells cultured in complete medium (CM199) that contained TGF beta3 expressed SMA, whereas cells cultured in CM199 alone did not. At the onset of the endothelial-mesenchymal transformation, migrating mesenchymal cells express SMA and the expression of this form of actin is upregulated by TGF beta3. The induction of the expression of SMA by TGF beta3 is one of the initial events in the cytoskeletal reorganization in endothelial cells which separate from one another during the initial phenotypic change associated with the endothelial-mesenchymal transformation.

Hiroaki Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • roles of tgfβ and bmp during valvulo septal Endocardial Cushion formation
    Anatomical Science International, 2009
    Co-Authors: Toshiyuki Yamagishi, Katsumi Ando, Hiroaki Nakamura
    Abstract:

    The primordia of valves and the atrioventricular septum arise from Endocardial Cushion tissue that is formed in the outflow tract (OFT) and in the atrioventricular (AV) regions during cardiogenesis. Abnormal development of the Endocardial Cushion results in various congenital heart diseases. Endocardial epithelial–mesenchymal transformation (EMT) is a critical process in Cushion tissue formation and is regulated by many factors, such as growth factors, intercellular signaling molecules, transcription factors, and extracellular matrices. A signal that is produced by the myocardium of the AV and OFT regions and transferred to the adjacent endocardium across the extracellular matrix mediates EMT. Studies in vitro and genetic analyses have shown that transforming growth factor β and bone morphogenetic protein play central roles in the regulation of EMT during Cushion tissue formation.

  • expression of bone morphogenetic protein 5 gene during chick heart development possible roles in valvuloseptal Endocardial Cushion formation
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2001
    Co-Authors: Toshiyuki Yamagishi, Yuji Nakajima, Katsumi Ando, Shinichiro Nishimatsu, Tsutomu Nohno, Hiroaki Nakamura
    Abstract:

    The bone morphogenetic protein (BMP) family, comprising multifunctional peptide growth factors, regulates many developmental processes in a variety of tissues. We examined the spatiotemporal expression of BMP5 by in situ hybridization in chick embryonic hearts from stages 5 to 33. The BMP5 gene was first expressed in the endoderm underlying the precardiac mesoderm at stages 5 to 8. Thereafter, BMP5 expression was restricted to the myocardium of the atrioventricular (AV) canal and outflow tract (OT) regions, where the valvuloseptal Endocardial Cushion tissue is induced. These results suggest that BMP5 may play important roles not only in myocardial differentiation, but also in the formation and maintenance of Endocardial Cushion tissue. Anat Rec 264:313–316, 2001. © 2001 Wiley-Liss, Inc.

  • mechanisms involved in valvuloseptal Endocardial Cushion formation in early cardiogenesis roles of transforming growth factor tgf β and bone morphogenetic protein bmp
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2000
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Shigeru Hokari, Hiroaki Nakamura
    Abstract:

    Endothelial-mesenchymal transformation (EMT) is a critical event in the generation of the Endocardial Cushion, the primordia of the valves and septa of the adult heart. This embryonic phenomenon occurs in the outflow tract (OT) and atrioventricular (AV) canal of the embryonic heart in a spatiotemporally restricted manner, and is initiated by putative myocardially derived inductive signals (adherons) which are transferred to the endocardium across the cardiac jelly. Abnormal development of Endocardial Cushion tissue is linked to many congenital heart diseases. At the onset of EMT in chick cardiogenesis, transforming growth factor (TGFβ)-3 is expressed in transforming endothelial and invading mesenchymal cells, while bone morphogenetic protein (BMP)-2 is expressed in the subjacent myocardium. Three-dimensional collagen gel culture experiments of the AV endocardium show that 1) myocardially derived inductive signals upregulate the expression of AV endothelial TGFβ3 at the onset of EMT, 2) TGFβ3 needs to be expressed by these endothelial cells to trigger the initial phenotypic changes of EMT, and 3) myocardial BMP2 acts synergistically with TGFβ3 in the initiation of EMT. Anat Rec 258:119–127, 2000. © 2000 Wiley-Liss, Inc.

  • expression of smooth muscle alpha actin in mesenchymal cells during formation of avian Endocardial Cushion tissue a role for transforming growth factor β3
    Developmental Dynamics, 1997
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Vladimir Mironov, Hiroaki Nakamura, Rachel R Markwald
    Abstract:

    During early cardiac morphogenesis, outflow tract (OT) and atrio-ventricular (AV) endothelial cells differentiate into mesenchymal cells, which have characteristics of smooth muscle-like myofibroblasts, and which form Endocardial Cushion tissue, the primordia of valves, and septa in the adult heart. During this embryonic event, transforming growth factor β3 (TGFβ3) is an essential element in the progression of endothelial-transformation into mesenchyme. TGFβs are known to be a potent inducer for mesodermal differentiation and a promoter for differentiation of endothelial cells into smooth muscle-like cells. Using a monoclonal antibody against smooth muscle-specific alpha-actin (SMA), we examined the immunohistochemical staining of this form of actin in avian Endocardial Cushion tissue formation. To determine whether TGFβ3 initiates the expression of SMA, the pre-migratory AV endothelial monolayer was cultured with or without chicken recombinant TGFβ3 and the expression of SMA was examined immunochemically. Migrating mesenchymal cells expressed SMA beneath the cell surface membrane. These cells showed a reduction of endothelial specific marker antigen, QH1. Stationary endothelial cells did not express SMA. The deposition of SMA in the mesenchymal tissue persisted until the end of the fetal period. Pre-migratory endothelial cells cultured in complete medium (CM199) that contained TGFβ3 expressed SMA, whereas cells cultured in CM199 alone did not. At the onset of the endothelial-mesenchymal transformation, migrating mesenchymal cells express SMA and the expression of this form of actin is upregulated by TGFβ3. The induction of the expression of SMA by TGFβ3 is one of the initial events in the cytoskeletal reorganization in endothelial cells which separate from one another during the initial phenotypic change associated with the endothelial-mesenchymal transformation. Dev. Dyn. 209:296–309, 1997. © 1997 Wiley-Liss, Inc.

  • expression of smooth muscle alpha actin in mesenchymal cells during formation of avian Endocardial Cushion tissue a role for transforming growth factor β3
    Developmental Dynamics, 1997
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Vladimir Mironov, Hiroaki Nakamura, Roger R. Markwald
    Abstract:

    During early cardiac morphogenesis, outflow tract (OT) and atrio-ventricular (AV) endothelial cells differentiate into mesenchymal cells, which have characteristics of smooth muscle-like myofibroblasts, and which form Endocardial Cushion tissue, the primordia of valves, and septa in the adult heart. During this embryonic event, transforming growth factor beta3 (TGF beta3) is an essential element in the progression of endothelial-transformation into mesenchyme. TGF beta(s) are known to be a potent inducer for mesodermal differentiation and a promoter for differentiation of endothelial cells into smooth muscle-like cells. Using a monoclonal antibody against smooth muscle-specific alpha-actin (SMA), we examined the immunohistochemical staining of this form of actin in avian Endocardial Cushion tissue formation. To determine whether TGF beta3 initiates the expression of SMA, the pre-migratory AV endothelial monolayer was cultured with or without chicken recombinant TGF beta3 and the expression of SMA was examined immunochemically. Migrating mesenchymal cells expressed SMA beneath the cell surface membrane. These cells showed a reduction of endothelial specific marker antigen, QH1. Stationary endothelial cells did not express SMA. The deposition of SMA in the mesenchymal tissue persisted until the end of the fetal period. Pre-migratory endothelial cells cultured in complete medium (CM199) that contained TGF beta3 expressed SMA, whereas cells cultured in CM199 alone did not. At the onset of the endothelial-mesenchymal transformation, migrating mesenchymal cells express SMA and the expression of this form of actin is upregulated by TGF beta3. The induction of the expression of SMA by TGF beta3 is one of the initial events in the cytoskeletal reorganization in endothelial cells which separate from one another during the initial phenotypic change associated with the endothelial-mesenchymal transformation.

Toshiyuki Yamagishi - One of the best experts on this subject based on the ideXlab platform.

  • roles of tgfβ and bmp during valvulo septal Endocardial Cushion formation
    Anatomical Science International, 2009
    Co-Authors: Toshiyuki Yamagishi, Katsumi Ando, Hiroaki Nakamura
    Abstract:

    The primordia of valves and the atrioventricular septum arise from Endocardial Cushion tissue that is formed in the outflow tract (OFT) and in the atrioventricular (AV) regions during cardiogenesis. Abnormal development of the Endocardial Cushion results in various congenital heart diseases. Endocardial epithelial–mesenchymal transformation (EMT) is a critical process in Cushion tissue formation and is regulated by many factors, such as growth factors, intercellular signaling molecules, transcription factors, and extracellular matrices. A signal that is produced by the myocardium of the AV and OFT regions and transferred to the adjacent endocardium across the extracellular matrix mediates EMT. Studies in vitro and genetic analyses have shown that transforming growth factor β and bone morphogenetic protein play central roles in the regulation of EMT during Cushion tissue formation.

  • rock1 expression is regulated by tgfβ3 and alk2 during valvuloseptal Endocardial Cushion formation
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2008
    Co-Authors: Masahide Sakabe, Toshiyuki Yamagishi, Hirokazu Sakata, Hiroko Matsui, Kazuo Ikeda, Yuji Nakajima
    Abstract:

    During early heart development at the looped heart stage, endothelial cells in the outflow tract and atrioventricular (AV) regions transform into mesenchyme to generate Endocardial Cushion tissue. This Endocardial epithelial–mesenchymal transition (EMT) is regulated by several regulatory pathways, including the transforming growth factor-beta (TGFβ), bone morphogenetic protein (BMP), and Rho-ROCK pathways. Here, we investigated the spatiotemporal expression pattern of ROCK1 mRNA during EMT in chick and examined whether TGFβ or BMP could induce the expression of ROCK1. At the onset of EMT, ROCK1 expression was up-regulated in endothelial/mesenchymal cells. A three-dimensional collagen gel assay was used to examine the mechanisms regulating the expression of ROCK1. In AV endocardium co-cultured with associated myocardium, ROCK1 expression was inhibited by either anti-TGFβ3 antibody, anti-ALK2 antibody or noggin, but not SB431542 (ALK5 inhibitor). In cultured preactivated AV endocardium, TGFβ3 protein induced the expression of ROCK1, but BMP did not. AV endothelial cells that were cultured in medium supplemented with TGFβ3 plus anti-ALK2 antibody failed to express ROCK1. These results suggest that the expression of ROCK1 is up-regulated at the onset of EMT and that signaling mediated by TGFβ3/ALK2 together with BMP is involved in the expression of ROCK1. Anat Rec, 291:845-857, 2008. © 2008 Wiley-Liss, Inc.

  • rho kinases regulate endothelial invasion and migration during valvuloseptal Endocardial Cushion tissue formation
    Developmental Dynamics, 2006
    Co-Authors: Masahide Sakabe, Toshiyuki Yamagishi, Kazuo Ikeda, Kazuki Nakatani, Norifumi Kawada, Kyoko Imanakayoshida, Toshimichi Yoshida, Yuji Nakajima
    Abstract:

    Rho-associated kinase (ROCK) is a downstream effector of small Rho-GTPases, and phosphorylates several substrates to regulate cell functions, including actin cytoskeletal reorganization and cellular motility. Endothelial–mesenchymal transformation (EMT) is a critical event in the formation of valves and septa during cardiogenesis. It has been reported that ROCK plays an important role in the regulation of Endocardial cell differentiation and migration during mouse cardiogenesis (Zhao and Rivkees [2004] Dev. Biol. 275:183–191). Immunohistochemistry showed that, during chick cardiogenesis, ROCK1 and -2 were expressed in the transforming and migrating endothelial/mesenchymal cells in the outflow tract (OT) and atrioventricular (AV) canal regions from which valvuloseptal Endocardial Cushion tissue would later develop. Treatment with Y27632, a specific ROCK inhibitor, of cultured AV explants or AV endothelial monolayers of stage 14-minus heart (preactivated stage for EMT) on three-dimensional collagen gel perturbed the seeding of mesenchymal cells into the gel lattice. In these experiments, Y27632 did not suppress the expression of an early transformation marker, smooth muscle α-actin. Moreover, Y27632 inhibited the mesenchymal invasion in stage 14–18 AV explants, in which endothelial cells had committed to undergo EMT. ML-9, a myosin light chain kinase inhibitor, also inhibited the mesenchymal invasion in cultured AV explants. These results suggest that ROCKs have a critical role in the mesenchymal cell invasion/migration that occurs at the late onset of EMT. Developmental Dynamics 235:94–104, 2006. © 2005 Wiley-Liss, Inc.

  • expression of bone morphogenetic protein 5 gene during chick heart development possible roles in valvuloseptal Endocardial Cushion formation
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2001
    Co-Authors: Toshiyuki Yamagishi, Yuji Nakajima, Katsumi Ando, Shinichiro Nishimatsu, Tsutomu Nohno, Hiroaki Nakamura
    Abstract:

    The bone morphogenetic protein (BMP) family, comprising multifunctional peptide growth factors, regulates many developmental processes in a variety of tissues. We examined the spatiotemporal expression of BMP5 by in situ hybridization in chick embryonic hearts from stages 5 to 33. The BMP5 gene was first expressed in the endoderm underlying the precardiac mesoderm at stages 5 to 8. Thereafter, BMP5 expression was restricted to the myocardium of the atrioventricular (AV) canal and outflow tract (OT) regions, where the valvuloseptal Endocardial Cushion tissue is induced. These results suggest that BMP5 may play important roles not only in myocardial differentiation, but also in the formation and maintenance of Endocardial Cushion tissue. Anat Rec 264:313–316, 2001. © 2001 Wiley-Liss, Inc.

  • mechanisms involved in valvuloseptal Endocardial Cushion formation in early cardiogenesis roles of transforming growth factor tgf β and bone morphogenetic protein bmp
    Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2000
    Co-Authors: Yuji Nakajima, Toshiyuki Yamagishi, Shigeru Hokari, Hiroaki Nakamura
    Abstract:

    Endothelial-mesenchymal transformation (EMT) is a critical event in the generation of the Endocardial Cushion, the primordia of the valves and septa of the adult heart. This embryonic phenomenon occurs in the outflow tract (OT) and atrioventricular (AV) canal of the embryonic heart in a spatiotemporally restricted manner, and is initiated by putative myocardially derived inductive signals (adherons) which are transferred to the endocardium across the cardiac jelly. Abnormal development of Endocardial Cushion tissue is linked to many congenital heart diseases. At the onset of EMT in chick cardiogenesis, transforming growth factor (TGFβ)-3 is expressed in transforming endothelial and invading mesenchymal cells, while bone morphogenetic protein (BMP)-2 is expressed in the subjacent myocardium. Three-dimensional collagen gel culture experiments of the AV endocardium show that 1) myocardially derived inductive signals upregulate the expression of AV endothelial TGFβ3 at the onset of EMT, 2) TGFβ3 needs to be expressed by these endothelial cells to trigger the initial phenotypic changes of EMT, and 3) myocardial BMP2 acts synergistically with TGFβ3 in the initiation of EMT. Anat Rec 258:119–127, 2000. © 2000 Wiley-Liss, Inc.

Todd D Camenisch - One of the best experts on this subject based on the ideXlab platform.

  • mekk3 initiates transforming growth factor β2 dependent epithelial to mesenchymal transition during Endocardial Cushion morphogenesis
    Circulation Research, 2008
    Co-Authors: Mark V Stevens, Derrick Broka, Patti Parker, Elisa Rogowitz, Richard R Vaillancourt, Todd D Camenisch
    Abstract:

    Congenital heart defects occur at a rate of 5% and are the most prevalent birth defects. A better understanding of the complex signaling networks regulating heart development is necessary to improve repair strategies for congenital heart defects. The mitogen-activated protein 3 kinase (MEKK3) is important to early embryogenesis, but developmental processes affected by MEKK3 during heart morphogenesis have not been fully examined. We identify MEKK3 as a critical signaling molecule during Endocardial Cushion development. We report the detection of MEKK3 transcripts to embryonic hearts before, during, and after cardiac Cushion cells have executed epithelial-to-mesenchymal transition (EMT). MEKK3 is observed to Endocardial cells of the cardiac Cushions with a diminishing gradient of expression into the Cushions. These observations suggest that MEKK3 may function during production of Cushion mesenchyme as required for valvular development and septation of the heart. We used a kinase inactive form of MEKK3 (MEKK3 KI ) in an in vitro assay that recapitulates in vivo EMT and show that MEKK3 KI attenuates mesenchyme formation. Conversely, constitutively active MEKK3 (ca-MEKK3) triggers mesenchyme production in ventricular endocardium, a tissue that does not normally undergo EMT. MEKK3-driven mesenchyme production is further substantiated by increased expression of EMT-relevant genes, including TGFβ 2 , Has2, and periostin. Furthermore, we show that MEKK3 stimulates EMT via a TGFβ 2 -dependent mechanism. Thus, the activity of MEKK3 is sufficient for developmental EMT in the heart. This knowledge provides a basis to understand how MEKK3 integrates signaling cascades activating Endocardial Cushion EMT.

  • elevated glucose inhibits vegf a mediated Endocardial Cushion formation modulation by pecam 1 and mmp 2
    Journal of Cell Biology, 2003
    Co-Authors: Josephine Enciso, Todd D Camenisch, Dita Gratzinger, Sandra Canosa, Emese Pinter, Joseph A Madri
    Abstract:

    Atrioventricular (AV) septal defects resulting from aberrant Endocardial Cushion (EC) formation are observed at increased rates in infants of diabetic mothers. EC formation occurs via an epithelial-mesenchymal transformation (EMT), involving transformation of Endocardial cells into mesenchymal cells, migration, and invasion into extracellular matrix. Here, we report that elevated glucose inhibits EMT by reducing myocardial vascular endothelial growth factor A (VEGF-A). This effect is reversed with exogenous recombinant mouse VEGF-A165, whereas addition of soluble VEGF receptor-1 blocks EMT. We show that disruption of EMT is associated with persistence of platelet endothelial cell adhesion molecule-1 (PECAM-1) and decreased matrix metalloproteinase-2 (MMP-2) expression. These findings correlate with retention of a nontransformed Endocardial sheet and lack of invasion. The MMP inhibitor GM6001 blocks invasion, whereas explants from PECAM-1 deficient mice exhibit MMP-2 induction and normal EMT in high glucose. PECAM-1–negative endothelial cells are highly motile and express more MMP-2 than do PECAM-1–positive endothelial cells. During EMT, loss of PECAM-1 similarly promotes single cell motility and MMP-2 expression. Our findings suggest that high glucose-induced inhibition of AV Cushion morphogenesis results from decreased myocardial VEGF-A expression and is, in part, mediated by persistent Endocardial cell PECAM-1 expression and failure to up-regulate MMP-2 expression.

  • temporal and distinct tgfβ ligand requirements during mouse and avian Endocardial Cushion morphogenesis
    Developmental Biology, 2002
    Co-Authors: Todd D Camenisch, Daniel G M Molin, Anthony D Person, Raymond B Runyan, Adriana Gittenbergerde C Groot, John A Mcdonald, Scott E Klewer
    Abstract:

    The formation of Endocardial Cushions in the atrioventricular (AV) canal of the rudimentary heart requires epithelial-to-mesenchymal cell transformation (EMT). This is a complex developmental process regulated by multiple extracellular signals and transduction pathways. A collagen gel assay, long used to examine Endocardial Cushion development in avian models, is now being employed to investigate genetically engineered mouse models with abnormal heart morphogenesis. In this study, we determine interspecies variations for avian and mouse cultured Endocardial Cushion explants. Considering these observed morphologic differences, we also define the temporal requirements for TGFbeta2 and TGFbeta3 during mouse Endocardial Cushion morphogenesis. TGFbeta2 and TGFbeta3 blocking antibodies inhibit endothelial cell activation and transformation, respectively, in avian explants. In contrast, neutralizing TGFbeta2 inhibits cell transformation in the mouse, while TGFbeta3 antibodies have no effect on activation or transformation events. This functional requirement for TGFbeta2 is concomitant with expression of TGFbeta2, but not TGFbeta3, within mouse Endocardial Cushions at a time coincident with transformation. Thus, both TGFbeta2 and TGFbeta3 appear necessary for the full morphogenetic program of EMT in the chick, but only TGFbeta2 is expressed and obligatory for mammalian Endocardial Cushion cell transformation.

  • a novel role for vegf in Endocardial Cushion formation and its potential contribution to congenital heart defects
    Development, 2001
    Co-Authors: Yuval Dor, Todd D Camenisch, Ahuva Itin, Glenn I Fishman, J A Mcdonald, Peter Carmeliet, Eli Keshet
    Abstract:

    Normal cardiovascular development is exquisitely dependent on the correct dosage of the angiogenic growth factor and vascular morphogen vascular endothelial growth factor (VEGF). However, cardiac expression of VEGF is also robustly augmented during hypoxic insults, potentially mediating the well-established teratogenic effects of hypoxia on heart development. We report that during normal heart morphogenesis VEGF is specifically upregulated in the atrioventricular (AV) field of the heart tube soon after the onset of Endocardial Cushion formation (i.e. the endocardium-derived structures that build the heart septa and valves). To model hypoxia-dependent induction of VEGF in vivo, we conditionally induced VEGF expression in the myocardium using a tetracycline-regulated transgenic system. Premature induction of myocardial VEGF in E9.5 embryos to levels comparable with those induced by hypoxia prevented formation of Endocardial Cushions. When added to explanted embryonic AV tissue, VEGF fully inhibited Endocardial-to-mesenchymal transformation. Transformation was also abrogated in AV explants subjected to experimental hypoxia but fully restored in the presence of an inhibitory soluble VEGF receptor 1 chimeric protein. Together, these results suggest a novel developmental role for VEGF as a negative regulator of Endocardial-to-mesenchymal transformation that underlies the formation of Endocardial Cushions. Moreover, ischemia-induced VEGF may be the molecular link between hypoxia and congenital defects in heart septation.