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E M De Robertis - One of the best experts on this subject based on the ideXlab platform.
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Spemann's organizer and the self-regulation of embryonic fields.
Mechanisms of Development, 2009Co-Authors: E M De RobertisAbstract:Embryos and developing organs have the remarkable ability of self-regenerating after experimental manipulations. In the Xenopus blastula half-embryos can regenerate the missing part, producing identical twins. Studies on the molecular nature of Spemann’s organizer have revealed that self-regulation results from the battle between two signaling centers under reciprocal transcriptional control. Long-range communication between the dorsal and ventral sides is mediated by the action of growth factor antagonists ‐ such as the BMP antagonist Chordin ‐ that regulate the flow of BMPs within the embryonic morphogenetic field. BMPs secreted by the dorsal Spemann organizer tissue are released by metalloproteinases of the Tolloid family, which cleave Chordin at a distance of where they were produced. The dorsal center secretes Chordin, Noggin, BMP2 and ADMP. The ventral center of the embryo secretes BMP4, BMP7, Sizzled, Crossveinless-2 and Tolloid-related. Crossveinless-2 binds Chordin/BMP complexes, facilitating their flow towards the ventral side, where BMPs are released by Tolloid allowing peak BMP signaling. Self-regulation occurs because transcription of ventral genes is induced by BMP while transcription of dorsal genes is repressed by BMP signals. This assures that for each action of Spemann’s organizer there is a reaction in the ventral side of the embryo. Because both dorsal and ventral centers express proteins of similar biochemical activities, they can compensate for each other. A novel biochemical pathway of extracellular growth factor signaling regulation has emerged from these studies in Xenopus. This remarkable dorsal‐ventral positional information network has been conserved in evolution and is ancestral to all bilateral animals.
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crossveinless 2 is a bmp feedback inhibitor that binds Chordin bmp to regulate xenopus embryonic patterning
Developmental Cell, 2008Co-Authors: Andrea L Ambrosio, Catherine Coffinier, Hojoon Lee, Vincent F Taelman, Carrie A Metzinger, E M De RobertisAbstract:Summary Vertebrate Crossveinless-2 (CV2) is a secreted protein that can potentiate or antagonize BMP signaling. Through embryological and biochemical experiments we find that: (1) CV2 functions as a BMP4 feedback inhibitor in ventral regions of the Xenopus embryo; (2) CV2 complexes with Twisted gastrulation and BMP4; (3) CV2 is not a substrate for tolloid proteinases; (4) CV2 binds to purified Chordin protein with high affinity (K D in the 1 nM range); (5) CV2 binds even more strongly to Chordin proteolytic fragments resulting from Tolloid digestion or to full-length Chordin/BMP complexes; (6) CV2 depletion causes the Xenopus embryo to become hypersensitive to the anti-BMP effects of Chordin overexpression or tolloid inhibition. We propose that the CV2/Chordin interaction may help coordinate BMP diffusion to the ventral side of the embryo, ensuring that BMPs liberated from Chordin inhibition by tolloid proteolysis cause peak signaling levels.
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expression of siamois and twin in the blastula Chordin noggin signaling center is required for brain formation in xenopus laevis embryos
Mechanisms of Development, 2008Co-Authors: Hideyuki Ishibashi, E M De Robertis, Noriko Matsumura, Hiroshi Hanafusa, Kunihiro Matsumoto, Hiroki KurodaAbstract:The blastula Chordin- and Noggin-expressing (BCNE) center located in the dorsal animal region of the Xenopus blastula embryo contains both prospective anterior neuroectoderm and Spemann organizer precursor cells. Here we show that, contrary to previous reports, the canonical Wnt target homeobox genes, Double knockdown of these genes using antisense morpholinos in Xenopus laevis blocked head formation, reduced the expression of the other BCNE center genes, upregulated Bmp4 expression, and nullified hyperdorsalization by lithium chloride. Moreover, gain- and loss-of-function experiments showed that Siamois and Twin expression is repressed by the vegetal transcription factor VegT. We propose that VegT expression causes maternal beta-Catenin signals to restrict Siamois and Twin expression to the BCNE region. A two-step inhibition of BMP signals by Siamois and Twin-- first by transcriptional repression of Bmp4 and then by activation of the expression of the BMP inhibitors Chordin and Noggin--in the BCNE center is required for head formation.
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embryonic dorsal ventral signaling secreted frizzled related proteins as inhibitors of tolloid proteinases
Cell, 2006Co-Authors: Hojoon Lee, Bruno Reversade, Andrea L Ambrosio, E M De RobertisAbstract:Here we report an unexpected role for the secreted Frizzled-related protein (sFRP) Sizzled/Ogon as an inhibitor of the extracellular proteolytic reaction that controls BMP signaling during Xenopus gastrulation. Microinjection experiments suggest that the Frizzled domain of Sizzled regulates the activity of Xolloid-related (Xlr), a metalloproteinase that degrades Chordin, through the following molecular pathway: Szl ┤ Xlr ┤ Chd ┤ BMP → P-Smad1 → Szl. In biochemical assays, the Xlr proteinase has similar affinities for its endogenous substrate Chordin and for its competitive inhibitor Sizzled, which is resistant to enzyme digestion. Extracellular levels of Sizzled and Chordin in the gastrula embryo and enzyme reaction constants were all in the 10−8 M range, consistent with a physiological role in the regulation of dorsal-ventral patterning. Sizzled is also a natural inhibitor of BMP1, a Tolloid metalloproteinase of medical interest. Furthermore, mouse sFRP2 inhibited Xlr, suggesting a wider role for this molecular mechanism.
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the role of Chordin bmp signals in mammalian pharyngeal development and digeorge syndrome
Development, 2003Co-Authors: Daniel Bachiller, John Klingensmith, Natalya Shneyder, Uyen Tran, Ryan M Anderson, Janet Rossant, E M De RobertisAbstract:The Chordin/Bmp system provides one of the best examples of extracellular signaling regulation in animal development. We present the phenotype produced by the targeted inactivation of the Chordin gene in mouse. Chordin homozygous mutant mice show, at low penetrance, early lethality and a ventralized gastrulation phenotype. The mutant embryos that survive die perinatally, displaying an extensive array of malformations that encompass most features of DiGeorge and Velo-Cardio-Facial syndromes in humans. Chordin secreted by the mesendoderm is required for the correct expression of Tbx1 and other transcription factors involved in the development of the pharyngeal region. The Chordin mutation provides a mouse model for head and neck congenital malformations that frequently occur in humans and suggests that Chordin/Bmp signaling may participate in their pathogenesis.
Mary C. Mullins - One of the best experts on this subject based on the ideXlab platform.
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proteolytic restriction of Chordin range underlies bmp gradient formation
Cell Reports, 2020Co-Authors: Francesca B Tuazon, Xu Wang, Jonathan Lee Andrade, David M Umulis, Mary C. MullinsAbstract:Summary A fundamental question in developmental biology is how morphogens, such as bone morphogenetic protein (BMP), form precise signaling gradients to impart positional and functional identity to the cells of the early embryo. We combine rigorous mutant analyses with quantitative immunofluorescence to determine that the proteases Bmp1a and Tolloid spatially restrict the BMP antagonist Chordin in dorsoventral (DV) axial patterning of the early zebrafish gastrula. We show that maternally deposited Bmp1a plays an unexpected and non-redundant role in establishing the BMP signaling gradient, while the Bmp1a/Tolloid antagonist Sizzled is surprisingly dispensable. Combining computational modeling and in vivo analyses with an immobile Chordin construct, we demonstrate that long-range Chordin diffusion is not necessary for BMP gradient formation and DV patterning. Our data do not support a counter-gradient of Chordin and instead favor a Chordin sink, established by Bmp1a and Tolloid, as the primary mechanism that drives BMP gradient formation.
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temporal and spatial action of tolloid mini fin and Chordin to pattern tail tissues
Developmental Biology, 2006Co-Authors: Stephanie A Connors, Jennifer A Tucker, Mary C. MullinsAbstract:In vertebrates, a bone morphogenetic protein (BMP) signaling pathway patterns all ventral cell fates along the embryonic axis. BMP activity is positively regulated by Tolloid, a metalloprotease, that can eliminate the activity of the BMP antagonist Chordin. A tolloid mutant in zebrafish, mini fin (mfn), exhibits a specific loss of ventral tail tissues. Here, we investigate the spatial and temporal requirements for Tolloid (Mfn) in dorsoventral patterning of the tail. Through chimeric analyses, we found that Tolloid (Mfn) functions cell non-autonomously in the ventral-most vegetal cells of the gastrula or their derivatives. We generated a tolloid transgene under the control of the inducible hsp70 promoter and demonstrate that tolloid (mfn) is first required at the completion of gastrulation. Although tolloid is expressed during gastrulation and dorsally and ventrally within the tail bud, our results indicate that Tolloid (Mfn) acts specifically in the ventral tail bud during a approximately 4 h period extending from the completion of gastrulation to early somitogenesis stages to regulate BMP signaling. Examination of the temporal requirements of Chordin activity by overexpression of the hsp70-tolloid transgene indicates that Chordin is required both during and after gastrulation for proper patterning of the tail, contrasting Tld's requirement only during post-gastrula stages. We hypothesize that the gastrula role of Chordin in tail patterning is to generate the proper size domains of cells to enter the ventral and dorsal tail bud, whereas post-gastrula Chordin activity patterns the derivatives of the tail bud. Thus, fine modulation of BMP signaling levels through the negative and positive actions of Chordin and Tolloid, respectively, patterns tail tissues.
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tolloid gets sizzled competing with Chordin
Developmental Cell, 2006Co-Authors: Mary C. MullinsAbstract:The enigma of Sizzled, a secreted Frizzled-related protein, has been resolved in a recent study from the De Robertis lab (Lee et al., 2006 [in the January 13 issue of Cell]). Sizzled, although homologous to other Wnt antagonists, does not function as such, nor does it function within a Wnt signaling pathway. Remarkably it functions as an antagonist of BMP signaling, competing with Chordin for binding to its inhibitor a Tolloid-related metalloprotease. This competition protects Chordin from cleavage, thus allowing it to bind and limit BMP signaling.
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Modulation of BMP activity in dorsal-ventral pattern formation by the Chordin and ogon antagonists.
Developmental Biology, 2002Co-Authors: Daniel S. Wagner, Mary C. MullinsAbstract:Abstract We analyzed the interactions between mutations in antagonistic BMP pathway signaling components to examine the roles that the antagonists play in regulating BMP signaling activity. The dorsalized mutants swirl/bmp2b , snailhouse/bmp7 , lost-a-fin/alk8 , and mini fin/tolloid were each analyzed in double mutant combinations with the ventralized mutants Chordino/Chordin and ogon, whose molecular nature is not known. Similar to the BMP antagonist Chordino , we found that the BMP ligand mutants swirl/bmp2b and snailhouse/bmp7 are also epistatic to the putative BMP pathway antagonist, ogon, excluding a class of intracellular antagonists as candidates for ogon . In ogon ; mini fin double mutants, we observed a mutual suppression of the ogon and mini fin mutant phenotypes, frequently to a wild type phenotype. Thus, the Tolloid/Mini fin metalloprotease that normally cleaves and inhibits Chordin activity is dispensable, when Ogon antagonism is reduced. These results suggest that Ogon encodes a Tolloid and Chordin-independent antagonistic function. By analyzing genes whose expression is very sensitive to BMP signaling levels, we found that the absence of Ogon or Chordin antagonism did not increase the BMP activity remaining in swirl/bmp2b or hypomorphic snailhouse/bmp7 mutants. These results, together with other studies, suggest that additional molecules or mechanisms are essential in generating the presumptive gastrula BMP activity gradient that patterns the dorsal–ventral axis. Lastly we observed a striking increased penetrance of the swirl/bmp2b dominant dorsalized phenotype, when Chordin function is also absent. Loss of the BMP antagonist Chordin is expected to increase BMP signaling levels in a swirl heterozygote, but instead we observed an apparent decrease in BMP signaling levels and a loss of ventral tail tissue. As has been proposed for the fly orthologue of Chordin , short gastrulation , our paradoxical results can be explained by a model whereby Chordin both antagonizes and promotes BMP activity.
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the role of tolloid mini fin in dorsoventral pattern formation of the zebrafish embryo
Development, 1999Co-Authors: Stephanie A Connors, Jamie Trout, Marc Ekker, Mary C. MullinsAbstract:A highly conserved TGF-b signaling pathway is involved in the establishment of the dorsoventral axis of the vertebrate embryo. Specifically, Bone Morphogenetic Proteins (Bmps) pattern ventral tissues of the embryo while inhibitors of Bmps, such as Chordin, Noggin and Follistatin, are implicated in dorsal mesodermal and neural development. We investigated the role of Tolloid, a metalloprotease that can cleave Chordin and increase Bmp activity, in patterning the dorsoventral axis of the zebrafish embryo. Injection of tolloid mRNA into six dorsalized mutants rescued only one of these mutants, mini fin. Through chromosomal mapping, linkage and cDNA sequence analysis of several mini fin alleles, we demonstrate that mini fin encodes the tolloid gene. Characterization of the mini fin mutant phenotype reveals that Mini fin/Tolloid activity is required for patterning ventral tissues of the tail: the ventral fin, and the ventroposterior somites and vasculature. Gene expression studies show that mfn mutants exhibit reduced expression of ventrally restricted markers at the end of gastrulation, suggesting that the loss of ventral tail tissues is caused by a dorsalization occurring at the end of gastrulation. Based on the mini fin mutant phenotype and the expression of tolloid, we propose that Mini fin/Tolloid modifes the Bmp activity gradient at the end of gastrulation, when the ventralmost marginal cells of the embryo are in close proximity to the dorsal Chordin-expressing cells. At this time, unimpeded Chordin may diffuse to the most ventral marginal regions and inhibit high Bmp activity levels. In the presence of Mini fin/Tolloid, however, Chordin activity would be negatively modulated through proteolytic cleavage, thereby increasing Bmp signaling activity. This extracellular mechanism is amplified by an autoregulatory loop for bmp gene expression.
Eddy M. De Robertis - One of the best experts on this subject based on the ideXlab platform.
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Dorsal-Ventral patterning: Crescent is a dorsally secreted Frizzled-related protein that competitively inhibits Tolloid proteases
Developmental Biology, 2011Co-Authors: Diego Ploper, Eddy M. De RobertisAbstract:In Xenopus, dorsal–ventral (D–V) patterning can self-regulate after embryo bisection. This is mediated by an extracellular network of proteins secreted by the dorsal and ventral centers of the gastrula. Different proteins of similar activity can be secreted at these two poles, but under opposite transcriptional control. Here we show that Crescent, a dorsal protein, can compensate for the loss of Sizzled, a ventral protein. Crescent is a secreted Frizzled-Related Protein (sFRP) known to regulate Wnt8 and Wnt11 activity. We now find that Crescent also regulates the BMP pathway. Crescent expression was increased by the BMP antagonist Chordin and repressed by BMP4, while the opposite was true for Sizzled. Crescent knock-down increased the expression of BMP target genes, and synergized with Sizzled morpholinos. Thus, Crescent loss-of-function is compensated by increased expression of its ventral counterpart Sizzled. Crescent overexpression dorsalized whole embryos but not ventral half-embryos, indicating that Crescent requires a dorsal component to exert its anti-BMP activity. Crescent protein lost its dorsalizing activity in Chordin-depleted embryos. When co-injected, Crescent and Chordin proteins greatly synergized in the dorsalization of Xenopus embryos. The molecular mechanism of these phenotypes is explained by the ability of Crescent to inhibit Tolloid metalloproteinases, which normally degrade Chordin. Enzyme kinetic studies showed that Crescent was a competitive inhibitor of Tolloid activity, which bound to Tolloid/BMP1 with a KD of 11 nM. In sum, Crescent is a new component of the D–V pathway, which functions as the dorsal counterpart of Sizzled, through the regulation of Chordinases of the Tolloid family.
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Depletion of Bmp2, Bmp4, Bmp7 and Spemann organizer signals induces massive brain formation in Xenopus embryos - eScholarship
2005Co-Authors: Bruno Reversade, Hiroki Kuroda, Hojoon Lee, Ashley Mays, Eddy M. De RobertisAbstract:To address the patterning function of the Bmp2, Bmp4 and Bmp7 growth factors, we designed antisense morpholino oligomers (MO) that block their activity in Xenopus laevis. Bmp4 knockdown was sufficient to rescue the ventralizing effects caused by loss of Chordin activity. Double Bmp4 and Bmp7 knockdown inhibited tail development. Triple Bmp2/Bmp4/Bmp7 depletion further compromised trunk development but did not eliminate dorsoventral patterning. Unexpectedly, we found that blocking Spemann organizer formation by UV treatment or beta-Catenin depletion caused BMP inhibition to have much more potent effects, abolishing all ventral development and resulting in embryos having radial central nervous system (CNS) structures. Surprisingly, dorsal signaling molecules such as Chordin, Noggin, Xnr6 and Cerberus were not re-expressed in these embryos. We conclude that BMP inhibition is sufficient for neural induction in vivo, and that in the absence of ventral BMPs, Spemann organizer signals are not required for brain formation.
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Depletion of Bmp2, Bmp4, Bmp7 and Spemann organizer signals induces massive brain formation in Xenopus embryos
Development, 2005Co-Authors: Bruno Reversade, Hiroki Kuroda, Hojoon Lee, Ashley Mays, Eddy M. De RobertisAbstract:To address the patterning function of the Bmp2, Bmp4 and Bmp7 growth factors, we designed antisense morpholino oligomers (MO) that block their activity in Xenopus laevis. Bmp4 knockdown was sufficient to rescue the ventralizing effects caused by loss of Chordin activity. Double Bmp4 and Bmp7 knockdown inhibited tail development. Triple Bmp2/Bmp4/Bmp7 depletion further compromised trunk development but did not eliminate dorsoventral patterning. Unexpectedly, we found that blocking Spemann organizer formation by UV treatment or beta-Catenin depletion caused BMP inhibition to have much more potent effects, abolishing all ventral development and resulting in embryos having radial central nervous system (CNS) structures. Surprisingly, dorsal signaling molecules such as Chordin, Noggin, Xnr6 and Cerberus were not re-expressed in these embryos. We conclude that BMP inhibition is sufficient for neural induction in vivo, and that in the absence of ventral BMPs, Spemann organizer signals are not required for brain formation.
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Chordin Is Required for the Spemann Organizer Transplantation Phenomenon in Xenopus Embryos
Developmental Cell, 2003Co-Authors: Michael Oelgeschläger, Hiroki Kuroda, Bruno Reversade, Eddy M. De RobertisAbstract:We analyzed the Chordin requirement in Xenopus development. Targeting of both Chordin Xenopus laevis pseudoalleles with morpholino antisense oligomers (Chd-MO) markedly decreased Chordin production. Embryos developed with moderately reduced dorsoanterior structures and expanded ventroposterior tissues, phenocopying the zebrafish Chordino mutant. A strong requirement for Chordin in dorsal development was revealed by experimental manipulations. First, dorsalization by lithium chloride treatment was completely blocked by Chd-MO. Second, Chd-MO inhibited elongation and muscle differentiation in Activin-treated animal caps. Third, Chd-MO completely blocked the induction of the central nervous system (CNS), somites, and notochord by organizer tissue transplanted to the ventral side of host embryos. Unexpectedly, transplantations into the dorsal side revealed a cell-autonomous requirement of Chordin for neural plate differentiation.
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An evolutionarily conserved system that regulates dorsal-ventral patterning via the BMP, Chordin, Tolloid and Twisted gastrulation proteins
The International Journal of Developmental Biology, 2001Co-Authors: Eddy M. De Robertis, Edgar M. Pera, Jose Garcia-abreu, Juan Larraín, Michael Oelgeschläger, Catherine CoffinierAbstract:*Address correspondence to: Eddy M. De Robertis. Howard Hughes Medical Institute & Dept. of Biological Chemistry, University of California, Los Angeles, CA, USA. e-mail: derobert@hhmi.ucla.edu Dorsal-ventral patterning in vertebrate and Drosophila embryos is controlled by a system of interacting secreting proteins that include BMP, Chordin, Xolloid, Tolloid and Twisted gastrulation. Chordin, the molecule that generates the pattern, is a BMP antagonist that contains four cysteine rich (CR) domains that bind to BMP, blocking its binding to the receptor. Tolloid/Xolloid encodes a metalloproteinase that cleaves Chordin at two sites, restoring the ability of BMP to signal. Twisted gastrulation has two distinct and sequential activities in BMP signaling. First, Tsg makes Chordin a better BMP antagonist by forming a ternary complex that prevents binding of BMP to its cognate receptor. Second, after cleavage of Chordin by Xolloid, Tsg competes the residual activity of Chordin fragments and facilitates their degradation. This molecular pathway, in which Xolloid switches the activity of Tsg from a BMP antagonist to a pro-BMP signal once all endogenous full-length Chordin is degraded, helps explain how sharp borders between embryonic territories are generated during development.
Daniel S. Greenspan - One of the best experts on this subject based on the ideXlab platform.
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zebrafish Chordin like and Chordin are functionally redundant in regulating patterning of the dorsoventral axis
Developmental Biology, 2010Co-Authors: Amanda M Branam, Guy G Hoffman, Francisco Pelegri, Daniel S. GreenspanAbstract:Abstract Chordin is the prototype of a group of cysteine-rich domain-containing proteins that bind and modulate signaling of various TGFβ-like ligands. Chordin-like 1 and 2 (CHL1 and 2) are two members of this group that have been described in human, mouse, and chick. However, in vivo roles for CHL1 and 2 in early development are unknown due to lack of loss-of-function analysis. Here we identify and characterize zebrafish, Danio rerio, CHL (Chl). The chl gene is on a region of chromosome 21 syntenic with the area of murine chromosome 7 bearing the CHL2 gene. Inability to identify a separate zebrafish gene corresponding to the mammalian CHL1 gene suggests that Chl may serve roles in zebrafish distributed between CHL1 and CHL2 in other species. Chl is a maternal factor that is also zygotically expressed later in development and has spatiotemporal expression patterns that differ from but overlap those of zebrafish Chordin (Chd), suggesting differences but also possible overlap in developmental roles of the two proteins. Chl, like Chd, dorsalizes embryos upon overexpression and is cleaved by BMP1, which antagonizes this activity. Loss-of-function experiments demonstrate that Chl serves as a BMP antagonist with functions that overlap and are redundant with those of Chd in forming the dorsoventral axis.
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secreted frizzled related protein 2 is a procollagen c proteinase enhancer with a role in fibrosis associated with myocardial infarction
Nature Cell Biology, 2009Co-Authors: Koichi S. Kobayashi, David Wilkes, Thomas Grieskamp, Chikaomi Yamada, Guorui Huang, Gaoxiang Ge, Craig T. Basson, Andreas Kispert, Yue Zhang, Daniel S. GreenspanAbstract:Secreted frizzled-related proteins (sFRPs) were reported to antagonise Chordin processing by Sizzled, a tolloid-like metalloproteinase in Xenopus and zebrafish. Surprisingly, mammalian sFRP2 enhances the activity of tolloid-like metalloproteinases on procollagen C to modulate fibrosis associated with cardiac injury.
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cell surface heparan sulfate proteoglycans potentiate Chordin antagonism of bone morphogenetic protein signaling and are necessary for cellular uptake of Chordin
Journal of Biological Chemistry, 2004Co-Authors: Reema Jasuja, William N Pappano, Benjamin L Allen, Alan C Rapraeger, Daniel S. GreenspanAbstract:Signaling by bone morphogenetic proteins (BMPs) plays a central role in early embryonic patterning, organogenesis, and homeostasis in a broad range of species. Chordin, an extracellular antagonist of BMP signaling, is thought to readily diffuse in tissues, thus forming gradients of BMP inhibition that result in reciprocal gradients of BMP signaling. The latter determine cell fates along the embryonic dorsoventral axis. The secreted protein Twisted Gastrulation (TSG) is thought to help shape BMP signaling gradients by acting as a cofactor that enhances Chordin inhibition of BMP signaling. Here, we demonstrate that mammalian Chordin binds heparin with an affinity similar to that of factors known to functionally interact with heparan sulfate proteoglycans (HSPGs) in tissues. We further demonstrate that Chordin binding in mouse embryonic tissues was dependent upon its interaction with cell-surface HSPGs and that Chordin bound to cell-surface HSPGs (e.g. syndecans), but not to basement membranes containing the HSPG perlecan. Surprisingly, mammalian TSG did not bind heparin unless prebound to Chordin and/or BMP-4, although Drosophila TSG has been reported to bind heparin on its own. Results are also presented that indicate that Chordin-HSPG interactions strongly potentiate the antagonism of BMP signaling by Chordin and are necessary for the retention and uptake of Chordin by cells. These data and others regarding Chordin diffusion have implications for the paradigm of how Chordin is thought to regulate BMP signaling in the extracellular space and how gradients of BMP signaling are formed.
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homologues of twisted gastrulation are extracellular cofactors in antagonism of bmp signalling
Nature, 2001Co-Authors: Ian C Scott, William N Pappano, Ira L Blitz, Sarah A Maas, Daniel S. GreenspanAbstract:Twisted gastrulation (TSG) is involved in specifying the dorsal-most cell fate in Drosophila embryos1, but its mechanism of action is poorly understood. TSG has been proposed to modify the action of Short gastrulation (SOG), thereby increasing signalling by the bone morphogenetic protein (BMP) Decapentaplegic. SOG, an inhibitor of BMP signalling, is in turn inactivated by the protease Tolloid2,3. Here we identify Tsg gene products from human, mouse, Xenopus, zebrafish and chick. Expression patterns in mouse and Xenopus embryos are consistent with in vivo interactions between Tsg, BMPs and the vertebrate SOG orthologue, Chordin. We show that Tsg binds both the vertebrate Decapentaplegic orthologue BMP4 and Chordin, and that these interactions have multiple effects. Tsg increases Chordin's binding of BMP4, potentiates Chordin's ability to induce secondary axes in Xenopus embryos, and enhances Chordin cleavage by vertebrate tolloid-related proteases at a site poorly used in Tsg's absence; also, the presence of Tsg enhances the secondary axis-inducing activity of two products of Chordin cleavage. We conclude that Tsg acts as a cofactor in Chordin's antagonism of BMP signalling.
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spatiotemporal expression patterns of mammalian Chordin during postgastrulation embryogenesis and in postnatal brain
Developmental Dynamics, 2000Co-Authors: Ian C Scott, Barry M Steiglitz, Timothy G Clark, William N Pappano, Daniel S. GreenspanAbstract:Chordin is an antagonist of TGFβ-like bone morphogenetic proteins (BMPs) that plays roles in dorsoventral axis formation and in induction, maintenance and/or differentiation of neural tissue in early vertebrate embryogenesis. In contrast, little is known concerning possible roles for Chordin at later stages of vertebrate development and in the adult. To provide insights into possible postgastrulation roles for Chordin, we report the spatiotemporal expression patterns of Chordin in 8.5- to 15.5-dpc mouse embryos and in the postnatal mouse brain. Expression of Chordin in the primordia of most major organs from 10.5 dpc, including the brain, lung, heart, liver, kidney, thymus, and gut, suggests multiple functions for Chordin in organogenesis, potentially by means of interactions with TGFβ-like BMPs. The relatively high levels of Chordin expression in condensing and differentiating cartilage elements from 11.5 dpc indicates a generalized role for Chordin throughout embryonic skeletogenesis. In the postnatal mouse brain, we demonstrate that Chordin is coexpressed with other components of the TGFβ-like BMP signalling pathway in the cerebellum and hippocampus, sites of high synaptic plasticity, suggesting a role for Chordin in this process. Dev Den;217:449–456. © 2000 Wiley-Liss, Inc.
Matthias Hammerschmidt - One of the best experts on this subject based on the ideXlab platform.
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binding between crossveinless 2 and Chordin von willebrand factor type c domains promotes bmp signaling by blocking Chordin activity
PLOS ONE, 2010Co-Authors: Jinli Zhang, Lucy Patterson, Liyan Qiu, Daria Graziussi, Walter Sebald, Matthias HammerschmidtAbstract:Background Crossveinless-2 (CV2) is an extracellular BMP modulator protein of the Chordin family, which can either enhance or inhibit BMP activity. CV2 binds to BMP2 via subdomain 1 of the first of its five N-terminal von Willebrand factor type C domains (VWC1). Previous studies showed that this BMP binding is required for the anti-, but not for the pro-BMP effect of CV2. More recently, it was shown that CV2 can also bind to the BMP inhibitor Chordin. However, it remained unclear which domains mediate this binding, and whether it accounts for an anti- or pro-BMP effect. Principal Findings Here we report that a composite interface of CV2 consisting of subdomain 2 of VWC1 and of VWC2-4, which are dispensable for BMP binding, binds to the VWC2 domain of Chordin. Functional data obtained in zebrafish embryos indicate that this binding of Chordin is required for CV2's pro-BMP effect, which actually is an anti-Chordin effect and, at least to a large extent, independent of Tolloid-mediated Chordin degradation. We further demonstrate that CV2 mutant versions that per se are incapable of BMP binding can attenuate the Chordin/BMP interaction. Conclusions We have physically dissected the anti- and pro-BMP effects of CV2. Its anti-BMP effect is obtained by binding to BMP via subdomain1 of the VWC1 domain, a binding that occurs in competition with Chordin. In contrast, its pro-BMP effect is achieved by direct binding to Chordin via subdomain 2 of VWC1 and VWC2-4. This binding seems to induce conformational changes within the Chordin protein that weaken Chordin's affinity to BMP. We propose that in ternary Chordin-CV2-BMP complexes, both BMP and Chordin are directly associated with CV2, whereas Chordin is pushed away from BMP, ensuring that BMPs can be more easily delivered to their receptors.
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crystal structure analysis reveals how the Chordin family member crossveinless 2 blocks bmp 2 receptor binding
Developmental Cell, 2008Co-Authors: Jinli Zhang, Matthias Hammerschmidt, Lucy Patterson, Walter Sebald, Alexander Kotzsch, Stella E Weidauer, Thomas D MuellerAbstract:Summary Crossveinless 2 (CV-2) is an extracellular BMP modulator protein belonging to the Chordin family. During development it is expressed at sites of high BMP signaling and like Chordin CV-2 can either enhance or inhibit BMP activity. CV-2 binds to BMP-2 via its N-terminal Von Willebrand factor type C (VWC) domain 1. Here we report the structure of the complex between CV-2 VWC1 and BMP-2. The tripartite VWC1 binds BMP-2 only through a short N-terminal segment, called clip, and subdomain (SD) 1. Mutational analysis establishes that the clip segment and SD1 together create high-affinity BMP-2 binding. All four receptor-binding sites of BMP-2 are blocked in the complex, demonstrating that VWC1 acts as competitive inhibitor for all receptor types. In vivo experiments reveal that the BMP-enhancing (pro-BMP) activity of CV-2 is independent of BMP-2 binding by VWC1, showing that pro- and anti-BMP activities are structurally separated in CV-2.
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asymmetric expression of the bmp antagonists Chordin and gremlin in the sea anemone nematostella vectensis implications for the evolution of axial patterning
Developmental Biology, 2006Co-Authors: Fabian Rentzsch, Michael Saina, Roman Anton, Matthias Hammerschmidt, Thomas W Holstein, Ulrich TechnauAbstract:The evolutionary origin of the anterior-posterior and the dorsoventral body axes of Bilateria is a long-standing question. It is unclear how the main body axis of Cnidaria, the sister group to the Bilateria, is related to the two body axes of Bilateria. The conserved antagonism between two secreted factors, BMP2/4 (Dpp in Drosophila) and its antagonist Chordin (Short gastrulation in Drosophila) is a crucial component in the establishment of the dorsoventral body axis of Bilateria and could therefore provide important insight into the evolutionary origin of bilaterian axes. Here, we cloned and characterized two BMP ligands, dpp and GDF5-like as well as two secreted antagonists, Chordin and gremlin, from the basal cnidarian Nematostella vectensis. Injection experiments in zebrafish show that the ventralizing activity of NvDpp mRNA is counteracted by NvGremlin and NvChordin, suggesting that Gremlin and Chordin proteins can function as endogenous antagonists of NvDpp. Expression analysis during embryonic and larval development of Nematostella reveals asymmetric expression of all four genes along both the oral-aboral body axis and along an axis perpendicular to this one, the directive axis. Unexpectedly, NvDpp and NvChordin show complex and overlapping expression on the same side of the embryo, whereas NvGDF5-like and NvGremlin are both expressed on the opposite side. Yet, the two pairs of ligands and antagonists only partially overlap, suggesting complex gradients of BMP activity along the directive axis but also along the oral-aboral axis. We conclude that a molecular interaction between BMP-like molecules and their secreted antagonists was already employed in the common ancestor of Cnidaria and Bilateria to create axial asymmetries, but that there is no simple relationship between the oral-aboral body axis of Nematostella and one particular body axis of Bilateria.
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follistatin and noggin are excluded from the zebrafish organizer
Developmental Biology, 1998Co-Authors: Hermann Bauer, Andrea Meier, Marc Hild, Scott E Stachel, Aris N Economides, Dennis J Hazelett, Richard M Harland, Matthias HammerschmidtAbstract:Abstract The patterning activity of the Spemann organizer in early amphibian embryos has been characterized by a number of organizer-specific secreted proteins including Chordin, Noggin, and Follistatin, which all share the same inductive properties. They can neuralize ectoderm and dorsalize ventral mesoderm by blocking the ventralizing signals Bmp2 and Bmp4. In the zebrafish, null mutations in theChordingene, namedChordino, lead to a severe reduction of organizer activity, indicating that Chordino is an essential, but not the only, inductive signal generated by the zebrafish organizer. A second gene required for zebrafish organizer function ismercedes, but the molecular nature of its product is not known as yet. To investigate whether and how Follistatin and Noggin are involved in dorsoventral (D-V) patterning of the zebrafish embryo, we have now isolated and characterized their zebrafish homologues. Overexpression studies demonstrate that both proteins have the same dorsalizing properties as theirXenopushomologues. However, unlike theXenopusgenes, zebrafishfollistatinandnogginare not expressed in the organizer region, nor are they linked to themercedesmutation. Expression of both genes starts at midgastrula stages. While no patternednogginexpression was detectable byin situhybridization during gastrulation stages, later expression is confined to presumptive cartilage cells in the branchial arches and the neurocranium and to proximal regions of the pectoral fin buds.follistatintranscripts in gastrulating embryos are confined to anterior paraxial regions, which give rise to head mesoderm and the first five somites. The dorsolateral extent of this expression domain is regulated by Bmp2b, Chordino, and Follistatin itself. In addition, transient expression was observed in a subset of cells in the posterior notochord anlage. Later,follistatinis expressed in brain, eyes, and somites. Comparison of the spatiotemporal expression pattern offollistatinandnogginwith those ofbmp2bandbmp4and overexpression studies suggest that Noggin and Follistatin may function as Bmp antagonists in later processes of zebrafish development, including late phases of D-V patterning, to refine the early pattern set up by the interaction of Chordino and Bmp2/4. It thus appears that many, but not all, aspects of early dorsoventral patterning are shared among different vertebrate species.
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the molecular nature of zebrafish swirl bmp2 function is essential during early dorsoventral patterning
Development, 1997Co-Authors: Y Kishimoto, Matthias Hammerschmidt, K H Lee, Leonard I Zon, Stefan SchultemerkerAbstract:Early dorsoventral pattern formation in vertebrate embryos is regulated by opposing activities of ventralizing bone morphogenetic proteins (BMPs) and dorsal-specific BMP antagonists such as Chordin, Noggin and Follistatin. Specific defects in early dorsoventral patterning have been recently found in a number of zebrafish mutants, which exhibit either a ventralized or dorsalized phenotype. One of these, the ventralized mutant Chordino (originally called dino) is caused by a mutation in the zebrafish Chordin homologue and interacts genetically with the dorsalized mutant swirl. In swirl mutant embryos, dorsal structures such as notochord and somites are expanded while ventral structures such as blood and nephros are missing. Here we demonstrate that the swirl phenotype is caused by mutations in the zebrafish bmp2 gene (zbmp2). While injection of mRNAs encoded by the mutant alleles has no ventralizing effect, injection of wild-type zbmp2 mRNA leads to a complete rescue of the swirl mutant phenotype. Fertile adult mutant fish were obtained, showing that development after gastrulation is not dependent on zbmp2 function. In addition zBMP2 has no maternal role in mesoderm induction. Our analysis shows that swirl/BMP2, unlike mouse BMP2 but like mouse BMP4, is required for early dorsoventral patterning of the zebrafish embryo.