51
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Ortmann C, Pickhinke U, Exner S, Ohlig S, Lawrence R, Jboor H, Dreier R, Grobe K. Sonic hedgehog processing and release are regulated by glypican heparan sulfate proteoglycans. J Cell Sci 2015; 128:2374-85. [PMID: 25967551 DOI: 10.1242/jcs.170670] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/05/2015] [Indexed: 12/21/2022] Open
Abstract
All Hedgehog morphogens are released from producing cells, despite being synthesized as N- and C-terminally lipidated molecules, a modification that firmly tethers them to the cell membrane. We have previously shown that proteolytic removal of both lipidated peptides, called shedding, releases bioactive Sonic hedgehog (Shh) morphogens from the surface of transfected Bosc23 cells. Using in vivo knockdown together with in vitro cell culture studies, we now show that glypican heparan sulfate proteoglycans regulate this process, through their heparan sulfate chains, in a cell autonomous manner. Heparan sulfate specifically modifies Shh processing at the cell surface, and purified glycosaminoglycans enhance the proteolytic removal of N- and C-terminal Shh peptides under cell-free conditions. The most likely explanation for these observations is direct Shh processing in the extracellular compartment, suggesting that heparan sulfate acts as a scaffold or activator for Shh ligands and the factors required for their turnover. We also show that purified heparan sulfate isolated from specific cell types and tissues mediates the release of bioactive Shh from pancreatic cancer cells, revealing a previously unknown regulatory role for these versatile molecules in a pathological context.
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Affiliation(s)
- Corinna Ortmann
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Ute Pickhinke
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Sebastian Exner
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Stefanie Ohlig
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Roger Lawrence
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Hamodah Jboor
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany
| | - Rita Dreier
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany Cells-in-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
| | - Kay Grobe
- Institute for Physiological Chemistry and Pathobiochemistry, University of Münster, 48149 Münster, Germany Cells-in-Motion Cluster of Excellence (EXC1003-CiM), University of Münster, 48149 Münster, Germany
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52
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Venero Galanternik M, Kramer KL, Piotrowski T. Heparan Sulfate Proteoglycans Regulate Fgf Signaling and Cell Polarity during Collective Cell Migration. Cell Rep 2015; 10:414-428. [PMID: 25600875 PMCID: PMC4531098 DOI: 10.1016/j.celrep.2014.12.043] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/17/2014] [Accepted: 12/17/2014] [Indexed: 12/21/2022] Open
Abstract
Collective cell migration is a highly regulated morphogenetic movement during embryonic development and cancer invasion that involves the precise orchestration and integration of cell-autonomous mechanisms and environmental signals. Coordinated lateral line primordium migration is controlled by the regulation of chemokine receptors via compartmentalized Wnt/β-catenin and fibroblast growth factor (Fgf) signaling. Analysis of mutations in two exostosin glycosyltransferase genes (extl3 and ext2) revealed that loss of heparan sulfate (HS) chains results in a failure of collective cell migration due to enhanced Fgf ligand diffusion and loss of Fgf signal transduction. Consequently, Wnt/β-catenin signaling is activated ectopically, resulting in the subsequent loss of the chemokine receptor cxcr7b. Disruption of HS proteoglycan (HSPG) function induces extensive, random filopodia formation, demonstrating that HSPGs are involved in maintaining cell polarity in collectively migrating cells. The HSPGs themselves are regulated by the Wnt/β-catenin and Fgf pathways and thus are integral components of the regulatory network that coordinates collective cell migration with organ specification and morphogenesis.
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Affiliation(s)
- Marina Venero Galanternik
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Kenneth L Kramer
- Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, USA
| | - Tatjana Piotrowski
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA.
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53
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Akiyama T, Gibson MC. Morphogen transport: theoretical and experimental controversies. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:99-112. [PMID: 25581550 DOI: 10.1002/wdev.167] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 10/13/2014] [Indexed: 01/09/2023]
Abstract
UNLABELLED According to morphogen gradient theory, extracellular ligands produced from a localized source convey positional information to receiving cells by signaling in a concentration-dependent manner. How do morphogens create concentration gradients to establish positional information in developing tissues? Surprisingly, the answer to this central question remains largely unknown. During development, a relatively small number of morphogens are reiteratively deployed to ensure normal embryogenesis and organogenesis. Thus, the intracellular processing and extracellular transport of morphogens are tightly regulated in a tissue-specific manner. Over the past few decades, diverse experimental and theoretical approaches have led to numerous conflicting models for gradient formation. In this review, we summarize the experimental evidence for each model and discuss potential future directions for studies of morphogen gradients. For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Takuya Akiyama
- Stowers Institute for Medical Research, Kansas City, MO, USA
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54
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Abstract
Recent findings in several organ systems show that cytoneme-mediated signaling transports signaling proteins along cellular extensions and targets cell-to-cell exchanges to synaptic contacts. This mechanism of paracrine signaling may be a general one that is used by many (or all) cell types in many (or all) organs. We briefly review these findings in this perspective. We also describe the properties of several signaling systems that have previously been interpreted to support a passive diffusion mechanism of signaling protein dispersion, but can now be understood in the context of the cytoneme mechanism. Also watch the Video Abstract.
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Affiliation(s)
- Sougata Roy
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Thomas B. Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
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55
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Chang YH, Sun YH. Carrier of Wingless (Cow), a secreted heparan sulfate proteoglycan, promotes extracellular transport of Wingless. PLoS One 2014; 9:e111573. [PMID: 25360738 PMCID: PMC4216105 DOI: 10.1371/journal.pone.0111573] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 09/10/2014] [Indexed: 12/04/2022] Open
Abstract
Morphogens are signaling molecules that regulate growth and patterning during development by forming a gradient and activating different target genes at different concentrations. The extracellular distribution of morphogens is tightly regulated, with the Drosophila morphogen Wingless (Wg) relying on Dally-like (Dlp) and transcytosis for its distribution. However, in the absence of Dlp or endocytic activity, Wg can still move across cells along the apical (Ap) surface. We identified a novel secreted heparan sulfate proteoglycan (HSPG) that binds to Wg and promotes its extracellular distribution by increasing Wg mobility, which was thus named Carrier of Wg (Cow). Cow promotes the Ap transport of Wg, independent of Dlp and endocytosis, and this function addresses a previous gap in the understanding of Wg movement. This is the first example of a diffusible HSPG acting as a carrier to promote the extracellular movement of a morphogen.
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Affiliation(s)
- Yung-Heng Chang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Yi Henry Sun
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- * E-mail:
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56
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Guerrero I, Kornberg TB. Hedgehog and its circuitous journey from producing to target cells. Semin Cell Dev Biol 2014; 33:52-62. [PMID: 24994598 DOI: 10.1016/j.semcdb.2014.06.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/23/2014] [Indexed: 12/12/2022]
Abstract
The hedgehog (Hh) signaling protein has essential roles in the growth, development and regulation of many vertebrate and invertebrate organs. The processes that make Hh and prepare it for release from producing cells and that move it to target cells are both diverse and complex. This article reviews the essential features of these processes and highlights recent work that provides a novel framework to understand how these processes contribute to an integrated pathway.
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Affiliation(s)
- Isabel Guerrero
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain.
| | - Thomas B Kornberg
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA.
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57
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Hamaratoglu F, Affolter M, Pyrowolakis G. Dpp/BMP signaling in flies: from molecules to biology. Semin Cell Dev Biol 2014; 32:128-36. [PMID: 24813173 DOI: 10.1016/j.semcdb.2014.04.036] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/30/2014] [Indexed: 01/08/2023]
Abstract
Decapentaplegic (Dpp), the fly homolog of the secreted mammalian BMP2/4 signaling molecules, is involved in almost all aspects of fly development. Dpp has critical functions at all developmental stages, from patterning of the eggshell to the determination of adult intestinal stem cell identity. Here, we focus on recent findings regarding the transcriptional regulatory logic of the pathway, on a new feedback regulator, Pentagone, and on Dpp's roles in scaling and growth of the Drosophila wing.
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Affiliation(s)
- Fisun Hamaratoglu
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.
| | - Markus Affolter
- Growth & Development, Biozentrum, University of Basel, Basel, Switzerland
| | - George Pyrowolakis
- Institute for Biology I, Albert-Ludwigs-University of Freiburg, Freiburg, Germany; Centre for Biological Signaling Studies (BIOSS), Albert-Ludwigs-University of Freiburg, Freiburg, Germany
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58
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Abstract
Numerous proteins, including cytokines and chemokines, enzymes and enzyme inhibitors, extracellular matrix proteins, and membrane receptors, bind heparin. Although they are traditionally classified as heparin-binding proteins, under normal physiological conditions these proteins actually interact with the heparan sulfate chains of one or more membrane or extracellular proteoglycans. Thus, they are more appropriately classified as heparan sulfate-binding proteins (HSBPs). This review provides an overview of the various modes of interaction between heparan sulfate and HSBPs, emphasizing biochemical and structural insights that improve our understanding of the many biological functions of heparan sulfate.
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Affiliation(s)
- Ding Xu
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California 92093; ,
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59
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Wei KH, Liu IH. Heparan sulfate glycosaminoglycans modulate migration and survival in zebrafish primordial germ cells. Theriogenology 2014; 81:1275-85.e1-2. [PMID: 24629592 DOI: 10.1016/j.theriogenology.2014.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 01/09/2014] [Accepted: 02/06/2014] [Indexed: 11/17/2022]
Abstract
Early in embryonic development, primordial germ cells (PGCs) are specified and migrate from the site of their origin to where the gonad develops, following a specific route. Heparan sulfate glycosaminoglycans (HS-GAGs) are ubiquitous in extracellular matrix and the cell surface and have long been speculated to play a role during the migration of PGCs. In line with this speculation, whole-mount immunohistochemistry revealed the existence of HS-GAGs in the vicinity of migrating PGCs in early zebrafish embryos. To examine the roles of HS-GAGs during PGC migration, zebrafish heparanase 1 (hpse1), which degrades HS-GAGs, was cloned and overexpressed specifically in PGCs. The guidance signal for the migration of PGCs was disrupted with the overexpression of hpse1, as cluster formation and marginal localization at the blastoderm were significantly perturbed at 6 hours postfertilization. Furthermore, the number of PGCs was significantly decreased with the lack of vicinal HS-GAGs, as observed in the whole-mount in situ hybridization and quantitative PCR of the PGC marker gene vasa. Terminal deoxynucleotidyl transferase dUTP nick-end labeling indicated significantly increased apoptosis in PGCs overexpressing hpse1, suggesting that HS-GAGs contribute to the maintenance of PGC survival. In conclusion, HS-GAGs play multifaceted roles in PGCs during migration and are required both for guidance signals and multiplication of PGCs.
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Affiliation(s)
- Ke-Hsuan Wei
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - I-Hsuan Liu
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan; Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan.
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60
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Constam DB. Regulation of TGFβ and related signals by precursor processing. Semin Cell Dev Biol 2014; 32:85-97. [PMID: 24508081 DOI: 10.1016/j.semcdb.2014.01.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 01/29/2014] [Indexed: 10/25/2022]
Abstract
Secreted cytokines of the TGFβ family are found in all multicellular organisms and implicated in regulating fundamental cell behaviors such as proliferation, differentiation, migration and survival. Signal transduction involves complexes of specific type I and II receptor kinases that induce the nuclear translocation of Smad transcription factors to regulate target genes. Ligands of the BMP and Nodal subgroups act at a distance to specify distinct cell fates in a concentration-dependent manner. These signaling gradients are shaped by multiple factors, including proteases of the proprotein convertase (PC) family that hydrolyze one or several peptide bonds between an N-terminal prodomain and the C-terminal domain that forms the mature ligand. This review summarizes information on the proteolytic processing of TGFβ and related precursors, and its spatiotemporal regulation by PCs during development and various diseases, including cancer. Available evidence suggests that the unmasking of receptor binding epitopes of TGFβ is only one (and in some cases a non-essential) function of precursor processing. Future studies should consider the impact of proteolytic maturation on protein localization, trafficking and turnover in cells and in the extracellular space.
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Affiliation(s)
- Daniel B Constam
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Bâtiment SV ISREC, Station 19, CH-1015 Lausanne, Switzerland.
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61
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Bischoff M, Gradilla AC, Seijo I, Andrés G, Rodríguez-Navas C, González-Méndez L, Guerrero I. Cytonemes are required for the establishment of a normal Hedgehog morphogen gradient in Drosophila epithelia. Nat Cell Biol 2013; 15:1269-81. [PMID: 24121526 PMCID: PMC3840581 DOI: 10.1038/ncb2856] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 08/29/2013] [Indexed: 12/13/2022]
Abstract
Hedgehog (Hh) signalling is important in development, stem cell biology and disease. In a variety of tissues, Hh acts as a morphogen to regulate growth and cell fate specification. Several hypotheses have been proposed to explain morphogen movement, one of which is transport along filopodia-like protrusions called cytonemes. Here, we analyse the mechanism underlying Hh movement in the wing disc and the abdominal epidermis of Drosophila melanogaster. We show that, in both epithelia, cells generate cytonemes in regions of Hh signalling. These protrusions are actin-based and span several cell diameters. Various Hh signalling components localize to cytonemes, as well as to punctate structures that move along cytonemes and are probably exovesicles. Using in vivo imaging, we show that cytonemes are dynamic structures and that Hh gradient establishment correlates with cytoneme formation in space and time. Indeed, mutant conditions that affect cytoneme formation reduce both cytoneme length and Hh gradient length. Our results suggest that cytoneme-mediated Hh transport is the mechanistic basis for Hh gradient formation.
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Affiliation(s)
- Marcus Bischoff
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Ana-Citlali Gradilla
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
| | - Irene Seijo
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
| | - Germán Andrés
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
| | - Carmen Rodríguez-Navas
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
| | - Laura González-Méndez
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
| | - Isabel Guerrero
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
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62
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Nadanaka S, Kitagawa H. EXTL2 controls liver regeneration and aortic calcification through xylose kinase-dependent regulation of glycosaminoglycan biosynthesis. Matrix Biol 2013; 35:18-24. [PMID: 24176719 DOI: 10.1016/j.matbio.2013.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/16/2013] [Accepted: 10/16/2013] [Indexed: 10/26/2022]
Abstract
The gene products of two members of the EXT gene family, EXT1 and EXT2, function together as a polymerase in the biosynthesis of heparan sulfate. EXTL2, one of the three EXT-like genes in the human genome that are homologous to EXT1 and EXT2, encodes an N-acetylhexosaminyltransferase. However, both the role of EXTL2 in glycosaminoglycan (GAG) biosynthesis and the biological significance of EXTL2 remain unclear. Interestingly, EXTL2 can transfer a GlcNAc residue to the tetrasaccharide linkage region when this region is phosphorylated by a xylose kinase 1 (FAM20B) and thereby terminate chain elongation. Production of GAGs was significantly higher in EXTL2-knockout mice than in wild-type mice. EXTL2-knockout mice are viable and apparently healthy during development and after birth. Therefore, EXTL2-knockout mice were analyzed following the experimental induction of two separate pathological conditions. Carbon tetrachloride (CCl4) was used to induce liver failure, and 5/6th nephrectomy in combination with a high-phosphate diet was used to induce chronic kidney disease (CKD). Under conditions of CCl4-induced liver failure, hepatocyte proliferation following CCl4 treatment was lower in EXTL2-knockout mice than in wild-type mice; consequently, liver regeneration was impaired in EXTL2-knockout mice. This reduction in hepatocyte proliferation resulted partially because EXTL2-knockout mice experienced less hepatocyte-growth-factor-mediated signaling than did wild-type mice. Under conditions of induced CKD, matrix mineralization in vascular smooth muscle cells (VSMCs) in aortic rings of EXTL2-knockout mice was enhanced relative to that in wild-type mice. Altered biosynthesis of GAGs in EXTL2-knockout mice affected bone-morphogenetic-protein signaling, and consequently enhanced the differentiation of VSMCs into osteoblasts. Taken together, these results indicated that the EXTL2-dependent mechanism that regulates GAG biosynthesis is important for the maintenance of tissue homeostasis under pathological conditions, that is, lack of EXTL2 causes GAG overproduction and structural changes of GAGs associated with pathological processes.
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Affiliation(s)
- Satomi Nadanaka
- Department of Biochemistry, Kobe Pharmaceutical University, Higashinada-ku, Kobe 658-8558, Japan
| | - Hiroshi Kitagawa
- Department of Biochemistry, Kobe Pharmaceutical University, Higashinada-ku, Kobe 658-8558, Japan.
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63
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The exostosin family: proteins with many functions. Matrix Biol 2013; 35:25-33. [PMID: 24128412 DOI: 10.1016/j.matbio.2013.10.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 12/13/2022]
Abstract
Heparan sulfates are complex sulfated molecules found in abundance at cell surfaces and in the extracellular matrix. They bind to and influence the activity of a variety of molecules like growth factors, proteases and morphogens and are thus involved in various cell-cell and cell-matrix interactions. The mammalian EXT proteins have glycosyltransferase activities relevant for HS chain polymerization, however their exact role in this process is still confusing. In this review, we summarize current knowledge about the biochemical activities and some proposed functions of the members of the EXT protein family and their roles in human disease.
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64
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Yamamoto S, Nakase H, Matsuura M, Honzawa Y, Matsumura K, Uza N, Yamaguchi Y, Mizoguchi E, Chiba T. Heparan sulfate on intestinal epithelial cells plays a critical role in intestinal crypt homeostasis via Wnt/β-catenin signaling. Am J Physiol Gastrointest Liver Physiol 2013; 305:G241-9. [PMID: 23744737 PMCID: PMC3742857 DOI: 10.1152/ajpgi.00480.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Heparan sulfate (HS), a constituent of HS proteoglycans (HSPGs), is a linear polysaccharide present on the cell surface. HSPGs modulate functions of several growth factors and signaling molecules. We examined whether small intestinal epithelial HS plays some roles in crypt homeostasis using intestinal epithelium cell (IEC)-specific HS-deficient C57Bl/6 mice. Survival rate after total body irradiation was significantly reduced in HS-deficient mice due to profound intestinal injury. HS-deficient IECs exhibited Wnt/β-catenin pathway disruption, decreased levels of β-catenin nuclear localization, and reduced expression of Wnt target genes, including Lgr5 during crypt regeneration. Moreover, epithelial HS increased Wnt binding affinity of IECs, promoted phosphorylation of Wnt coreceptor LRP6, and enhanced Wnt/β-catenin signaling following ex vivo stimulation with Wnt3a, whereas activation of canonical Wnt signaling following direct inhibition of glycogen synthase kinase-3β by lithium chloride was similar between HS-deficient and wild-type mice. Thus HS influences the binding affinity of IECs to Wnt, thereby promoting activation of canonical Wnt signaling and facilitating regeneration of small intestinal crypts after epithelial injury.
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Affiliation(s)
- Shuji Yamamoto
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto; ,2Japan Society for the Promotion of Science, Tokyo, Japan;
| | - Hiroshi Nakase
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
| | - Minoru Matsuura
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
| | - Yusuke Honzawa
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
| | - Kayoko Matsumura
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
| | - Norimitsu Uza
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
| | - Yu Yamaguchi
- 3Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California;
| | - Emiko Mizoguchi
- 4Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Tsutomu Chiba
- 1Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto;
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65
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Chang WL, Chang CW, Chang YY, Sung HH, Lin MD, Chang SC, Chen CH, Huang CW, Tung KS, Chou TB. The Drosophila GOLPH3 homolog regulates the biosynthesis of heparan sulfate proteoglycans by modulating the retrograde trafficking of exostosins. Development 2013; 140:2798-807. [DOI: 10.1242/dev.087171] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The exostosin (EXT) genes encode glycosyltransferases required for glycosaminoglycan chain polymerization in the biosynthesis of heparan sulfate proteoglycans (HSPGs). Mutations in the tumor suppressor genes EXT1 and EXT2 disturb HSPG biosynthesis and cause multiple osteochondroma (MO). How EXT1 and EXT2 traffic within the Golgi complex is not clear. Here, we show that Rotini (Rti), the Drosophila GOLPH3, regulates the retrograde trafficking of EXTs. A reduction in Rti shifts the steady-state distribution of EXTs to the trans-Golgi. These accumulated EXTs tend to be degraded and their re-entrance towards the route for polymerizing GAG chains is disengaged. Conversely, EXTs are mislocalized towards the transitional endoplasmic reticulum/cis-Golgi when Rti is overexpressed. Both loss of function and overexpression of rti result in incomplete HSPGs and perturb Hedgehog signaling. Consistent with Drosophila, GOLPH3 modulates the dynamic retention and protein stability of EXT1/2 in mammalian species. Our data demonstrate that GOLPH3 modulates the activities of EXTs, thus implicating a putative role for GOLPH3 in the formation of MO.
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Affiliation(s)
- Wei-Ling Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Che-Wei Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Yu-Yun Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Hsin-Ho Sung
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Ming-Der Lin
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Shu-Chuan Chang
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Chung-Hao Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Chia-Wei Huang
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Kuei-Shu Tung
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
| | - Tze-Bin Chou
- Institute of Molecular and Cellular Biology, National Taiwan University, No.1 Sec.4 Roosevelt Road, Taipei, 10617, Taiwan
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66
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Gradilla AC, Guerrero I. Hedgehog on the move: a precise spatial control of Hedgehog dispersion shapes the gradient. Curr Opin Genet Dev 2013; 23:363-73. [PMID: 23747033 DOI: 10.1016/j.gde.2013.04.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 01/28/2023]
Abstract
Hedgehog (Hh) as morphogen directs cell differentiation during development activating various target genes in a concentration dependent manner. The mechanisms that permit controlled Hh dispersion and gradient formation remain controversial. New research in the Drosophila wing disc epithelium has revealed a crucial role of Hh recycling for its release and transportation from source cells. Lipid modifications on Hh mediate key interactions with different elements of the pathway, which balance the retention and release of the molecule through the basolateral side of the epithelium, allowing its tight spatial control. Dispersion of Hh is also determined by its hydrophobic nature, and the mechanisms that include membrane-tethered transport of Hh are increasingly proposed.
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Affiliation(s)
- Ana-Citlali Gradilla
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
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67
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Sekine SU, Haraguchi S, Chao K, Kato T, Luo L, Miura M, Chihara T. Meigo governs dendrite targeting specificity by modulating ephrin level and N-glycosylation. Nat Neurosci 2013; 16:683-91. [PMID: 23624514 DOI: 10.1038/nn.3389] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/01/2013] [Indexed: 11/09/2022]
Abstract
Neural circuit assembly requires precise dendrite and axon targeting. We identified an evolutionarily conserved endoplasmic reticulum (ER) protein, Meigo, from a mosaic genetic screen in Drosophila melanogaster. Meigo was cell-autonomously required in olfactory receptor neurons and projection neurons to target their axons and dendrites to the lateral antennal lobe and to refine projection neuron dendrites into individual glomeruli. Loss of Meigo induced an unfolded protein response and reduced the amount of neuronal cell surface proteins, including Ephrin. Ephrin overexpression specifically suppressed the projection neuron dendrite refinement defect present in meigo mutant flies, and ephrin knockdown caused a similar projection neuron dendrite refinement defect. Meigo positively regulated the level of Ephrin N-glycosylation, which was required for its optimal function in vivo. Thus, Meigo, an ER-resident protein, governs neuronal targeting specificity by regulating ER folding capacity and protein N-glycosylation. Furthermore, Ephrin appears to be an important substrate that mediates Meigo's function in refinement of glomerular targeting.
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Affiliation(s)
- Sayaka U Sekine
- Department of Genetics, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
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68
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Abstract
The graded distribution of morphogens underlies many of the tissue patterns that form during development. How morphogens disperse from a localized source and how gradients in the target tissue form has been under debate for decades. Recent imaging studies and biophysical measurements have provided evidence for various morphogen transport models ranging from passive mechanisms, such as free or hindered extracellular diffusion, to cell-based dispersal by transcytosis or cytonemes. Here, we analyze these transport models using the morphogens Nodal, fibroblast growth factor and Decapentaplegic as case studies. We propose that most of the available data support the idea that morphogen gradients form by diffusion that is hindered by tortuosity and binding to extracellular molecules.
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Affiliation(s)
- Patrick Müller
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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69
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Abstract
The canonical Wnt/β-catenin pathway is an ancient and evolutionarily conserved signaling pathway that is required for the proper development of all metazoans, from the basal demosponge Amphimedon queenslandica to humans. Misregulation of Wnt signaling is implicated in many human diseases, making this pathway an intense area of research in industry as well as academia. In this review, we explore our current understanding of the molecular steps involved in the transduction of a Wnt signal. We will focus on how the critical Wnt pathway component, β-catenin, is in a "futile cycle" of constant synthesis and degradation and how this cycle is disrupted upon pathway activation. We describe the role of the Wnt pathway in major human cancers and in the control of stem cell self-renewal in the developing organism and in adults. Finally, we describe well-accepted criteria that have been proposed as evidence for the involvement of a molecule in regulating the canonical Wnt pathway.
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Affiliation(s)
- Kenyi Saito-Diaz
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232-8240, USA
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70
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Hayashi Y, Sexton TR, Dejima K, Perry DW, Takemura M, Kobayashi S, Nakato H, Harrison DA. Glypicans regulate JAK/STAT signaling and distribution of the Unpaired morphogen. Development 2013; 139:4162-71. [PMID: 23093424 DOI: 10.1242/dev.078055] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In Drosophila, ligands of the Unpaired (Upd) family activate the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway. The JAK/STAT pathway controls many developmental events, including multiple functions in the ovary. These include an early role in the germarium for specification of stalk cells and a later role in the vitellarium to pattern the follicular epithelium surrounding each cyst. In this latter role, graded JAK/STAT activation specifies three distinct anterior follicular cell fates, suggesting that Upd is a morphogen in this system. Consistent with the JAK/STAT activation pattern in the vitellarium, Upd forms a concentration gradient on the apical surface of the follicular epithelium with a peak at its source, the polar cells. Like many morphogens, signaling and distribution of Upd are regulated by the heparan sulfate proteoglycans (HSPGs) Dally and Dally-like. Mutations in these glypican genes and in heparan sulfate biosynthetic genes result in disruption of JAK/STAT signaling, loss or abnormal formation of the stalk and significant reduction in the accumulation of extracellular Upd. Conversely, forced expression of Dally causes ectopic accumulation of Upd in follicular cells. Furthermore, biochemical studies reveal that Upd and Dally bind each other on the surface of the cell membrane. Our findings demonstrate that Drosophila glypicans regulate formation of the follicular gradient of the Upd morphogen, Upd. Furthermore, we establish the follicular epithelium as a new model for morphogen signaling in complex organ development.
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Affiliation(s)
- Yoshiki Hayashi
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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71
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Zhang Y, You J, Ren W, Lin X. Drosophila glypicans Dally and Dally-like are essential regulators for JAK/STAT signaling and Unpaired distribution in eye development. Dev Biol 2013; 375:23-32. [PMID: 23313126 DOI: 10.1016/j.ydbio.2012.12.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 12/22/2012] [Accepted: 12/31/2012] [Indexed: 11/19/2022]
Abstract
The highly conserved janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is a well-known signaling system that is involved in many biological processes. In Drosophila, this signaling cascade is activated by ligands of the Unpaired (Upd) family. Therefore, the regulation of Upd distribution is one of the key issues in controlling the JAK/STAT signaling activity and function. Heparan sulfate proteoglycans (HSPGs) are macromolecules that regulate the distribution of many ligand proteins including Wingless, Hedgehog and Decapentaplegic (Dpp). Here we show that during Drosophila eye development, HSPGs are also required in normal Upd distribution and JAK/STAT signaling activity. Loss of HSPG biosynthesis enzyme Brother of tout-velu (Botv), Sulfateless (Sfl), or glypicans Division abnormally delayed (Dally) and Dally-like protein (Dlp) led to reduced levels of extracellular Upd and reduction in JAK/STAT signaling activity. Overexpression of dally resulted in the accumulation of Upd and up-regulation of the signaling activity. Luciferase assay also showed that Dally promotes JAK/STAT signaling activity, and is dependent on its heparin sulfate chains. These data suggest that Dally and Dlp are essential for Upd distribution and JAK/STAT signaling activity.
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Affiliation(s)
- Yan Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Science, Beijing 100101, China
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72
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Bilioni A, Sánchez-Hernández D, Callejo A, Gradilla AC, Ibáñez C, Mollica E, Carmen Rodríguez-Navas M, Simon E, Guerrero I. Balancing Hedgehog, a retention and release equilibrium given by Dally, Ihog, Boi and shifted/DmWif. Dev Biol 2012; 376:198-212. [PMID: 23276604 DOI: 10.1016/j.ydbio.2012.12.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 11/12/2012] [Accepted: 12/13/2012] [Indexed: 10/27/2022]
Abstract
Hedgehog can signal both at a short and long-range, and acts as a morphogen during development in various systems. We studied the mechanisms of Hh release and spread using the Drosophila wing imaginal disc as a model system for polarized epithelium. We analyzed the cooperative role of the glypican Dally, the extracellular factor Shifted (Shf, also known as DmWif), and the Immunoglobulin-like (Ig-like) and Fibronectin III (FNNIII) domain-containing transmembrane proteins, Interference hedgehog (Ihog) and its related protein Brother of Ihog (Boi), in the stability, release and spread of Hh. We show that Dally and Boi are required to prevent apical dispersion of Hh; they also aid Hh recycling for its release along the basolateral part of the epithelium to form a long-range gradient. Shf/DmWif on the other hand facilitates Hh movement restrained by Ihog, Boi and Dally, establishing equilibrium between membrane attachment and release of Hh. Furthermore, this protein complex is part of thin filopodia-like structures or cytonemes, suggesting that the interaction between Dally, Ihog, Boi and Shf/DmWif is required for cytoneme-mediated Hh distribution during gradient formation.
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Affiliation(s)
- Aphrodite Bilioni
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), C/Nicolas Cabrera 1, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain
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73
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The extracellular matrix proteoglycan perlecan facilitates transmembrane semaphorin-mediated repulsive guidance. Genes Dev 2012; 26:2222-35. [PMID: 23028146 DOI: 10.1101/gad.193136.112] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Drosophila transmembrane semaphorin-1a (Sema-1a) is a repulsive guidance cue that uses the Plexin A (PlexA) receptor during neural development. Sema-1a is required in axons to facilitate motor axon defasciculation at guidance choice points. We found that mutations in the trol gene strongly suppress Sema-1a-mediated repulsive axon guidance. trol encodes the phylogenetically conserved secreted heparan sulfate proteoglycan (HSPG) perlecan, a component of the extracellular matrix. Motor axon guidance defects in perlecan mutants resemble those observed in Sema-1a- and PlexA-null mutant embryos, and perlecan mutants genetically interact with PlexA and Sema-1a. Perlecan protein is found in both the CNS and the periphery, with higher expression levels in close proximity to motor axon trajectories and pathway choice points. Restoring perlecan to mutant motor neurons rescues perlecan axon guidance defects. Perlecan augments the reduction in phospho-focal adhesion kinase (phospho-FAK) levels that result from treating insect cells in vitro with Sema-1a, and genetic interactions among integrin, Sema-1a, and FAK in vivo support an antagonistic relationship between Sema-1a and integrin signaling. Therefore, perlecan is required for Sema-1a-PlexA-mediated repulsive guidance, revealing roles for extracellular matrix proteoglycans in modulating transmembrane guidance cue signaling during neural development.
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74
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Structural basis of heparan sulfate-specific degradation by heparinase III. Protein Cell 2012; 3:950-61. [PMID: 23011846 PMCID: PMC4875378 DOI: 10.1007/s13238-012-2056-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 06/17/2012] [Indexed: 01/07/2023] Open
Abstract
Heparinase III (HepIII) is a 73-kDa polysaccharide lyase (PL) that degrades the heparan sulfate (HS) polysaccharides at sulfate-rare regions, which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system. It functions in cleaving metazoan heparan sulfate (HS) and providing carbon, nitrogen and sulfate sources for host microorganisms. It has long been used to deduce the structure of HS and heparin motifs; however, the structure of its own is unknown. Here we report the crystal structure of the HepIII from Bacteroides thetaiotaomicron at a resolution of 1.6 Å. The overall architecture of HepIII belongs to the (α/α)₅ toroid subclass with an N-terminal toroid-like domain and a C-terminal β-sandwich domain. Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains. A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation. Asn260 and His464 neutralize the carboxylic group, whereas Tyr314 serves both as a general base in C-5 proton abstraction, and a general acid in a proton donation to reconstitute the terminal hydroxyl group, respectively. The structure of HepIII and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides.
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75
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Avanesov A, Blair SS. The Drosophila WIF1 homolog Shifted maintains glypican-independent Hedgehog signaling and interacts with the Hedgehog co-receptors Ihog and Boi. Development 2012; 140:107-16. [PMID: 23154411 DOI: 10.1242/dev.078444] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hedgehog (Hh) family proteins are secreted signaling ligands whose short- and long-range activities transform cellular fates in multiple contexts in organisms ranging from metazoans to humans. In the developing Drosophila wing, extracellular Hh binds to cell-bound glypican heparan sulfate proteoglycans (HSPGs) and the secreted protein Shifted (Shf), a member of Wnt inhibitory factor 1 (WIF1) family. The glypicans and Shf are required for long-range Hh movement and signaling; it has been proposed that Shf promotes long-range Hh signaling by reinforcing binding between Hh and the glypicans, and that much or all of glypican function in Hh signaling requires Shf. However, we will show here that Shf maintains short-range Hh signaling in the wing via a mechanism that does not require the presence of or binding to the Drosophila glypicans Dally and Dally-like protein. Conversely, we demonstrate interactions between Hh and the glypicans that are maintained, and even strengthened, in the absence of Shf. We present evidence that Shf binds to the CDO/BOC family Hh co-receptors Interference hedgehog (Ihog) and Brother of Ihog, suggesting that Shf regulates short-range Hh signaling through interactions with the receptor complex. In support of a functional interaction between Ihog and members of the Shf/WIF1 family, we show that Ihog can increase the Wnt-inhibitory activity of vertebrate WIF1; this result raises the possibility of interactions between WIF1 and vertebrate CDO/BOC family members.
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Affiliation(s)
- Andrei Avanesov
- Department of Zoology, University of Wisconsin, Madison, WI 53706, USA
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76
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Abstract
30 years after the identification of WNTs, their signal transduction has become increasingly complex, with the discovery of more than 15 receptors and co-receptors in seven protein families. The recent discovery of three receptor classes for the R-spondin family of WNT agonists further adds to this complexity. What emerges is an intricate network of receptors that form higher-order ligand-receptor complexes routing downstream signalling. These are regulated both extracellularly by agonists such as R-spondin and intracellularly by post-translational modifications such as phosphorylation, proteolytic processing and endocytosis.
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Affiliation(s)
- Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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77
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Ohlig S, Pickhinke U, Sirko S, Bandari S, Hoffmann D, Dreier R, Farshi P, Götz M, Grobe K. An emerging role of Sonic hedgehog shedding as a modulator of heparan sulfate interactions. J Biol Chem 2012; 287:43708-19. [PMID: 23118222 DOI: 10.1074/jbc.m112.356667] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Major developmental morphogens of the Hedgehog (Hh) family act at short range and long range to direct cell fate decisions in vertebrate and invertebrate tissues. To this end, Hhs are released from local sources and act at a distance on target cells that express the Hh receptor Patched. However, morphogen secretion and spreading are not passive processes because all Hhs are synthesized as dually (N- and C-terminal) lipidated proteins that firmly tether to the surface of producing cells. On the cell surface, Hhs associate with each other and with heparan sulfate (HS) proteoglycans. This raises the question of how Hh solubilization and spreading is achieved. We recently discovered that Sonic hedgehog (Shh) is solubilized by proteolytic processing (shedding) of lipidated peptide termini in vitro. Because unprocessed N termini block Patched receptor binding sites in the cluster, we further suggested that their proteolytic removal is required for simultaneous Shh activation. In this work we confirm inactivity of unprocessed protein clusters and demonstrate restored biological Shh function upon distortion or removal of N-terminal amino acids and peptides. We further show that N-terminal Shh processing targets and inactivates the HS binding Cardin-Weintraub (CW) motif, resulting in soluble Shh clusters with their HS binding capacities strongly reduced. This may explain the ability of Shh to diffuse through the HS-containing extracellular matrix, whereas other HS-binding proteins are quickly immobilized. Our in vitro findings are supported by the presence of CW-processed Shh in murine brain samples, providing the first in vivo evidence for Shh shedding and subsequent solubilization of N-terminal-truncated proteins.
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Affiliation(s)
- Stefanie Ohlig
- Institute for Physiological Chemistry and Pathobiochemistry, University Hospital Münster, Waldeyerstrasse 15, D-48149 Münster, Germany
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78
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Araujo H, Fontenele MR, da Fonseca RN. Position matters: variability in the spatial pattern of BMP modulators generates functional diversity. Genesis 2012; 49:698-718. [PMID: 21671348 DOI: 10.1002/dvg.20778] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone morphogenetic proteins (BMPs) perform a variety of functions during development. Considering a single BMP, what enables its multiple roles in tissues of varied sizes and shapes? What regulates the spatial distribution and activity patterns of the BMP in these different developmental contexts? Some BMP functions require controlling spread of the BMP morphogen, while others require formation of localized, high concentration peaks of BMP activity. Here we review work in Drosophila that describes spatial regulation of the BMP encoded by decapentaplegic (dpp) in different developmental contexts. We concentrate on extracellular modulation of BMP function and discuss the mechanisms that generate concentrated peaks of Dpp activity, subdivide territories of different activity levels or regulate spread of the Dpp morphogen from a point source. We compare these findings with data from vertebrates and non-model organisms to discuss how changes in the regulation of Dpp distribution by extracellular modulators may lead to variability in dpp function in different species.
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Affiliation(s)
- Helena Araujo
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, RJ, Brazil.
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79
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Abstract
Wnt proteins comprise a major family of signaling molecules that orchestrate and influence a myriad of cell biological and developmental processes. Although our understanding of the role of Wnt signaling in regulating development and affecting disease, such as cancer, has been ever increasing, the study of the Wnt proteins themselves has been painstaking and slow moving. Despite advances in the biochemical characterization of Wnt proteins, many mysteries remain unsolved. In contrast to other developmental signaling molecules, such as fibroblast growth factors (FGF), transforming growth factors (TGFβ), and Sonic hedgehog (Shh), Wnt proteins have not conformed to many standard methods of protein production, such as bacterial overexpression, and analysis, such as ligand-receptor binding assays. The reasons for their recalcitrant nature are likely a consequence of the complex set of posttranslational modifications involving several highly specialized and poorly characterized processing enzymes. With the recent description of the first Wnt protein structure, the time is ripe to uncover and possibly resolve many of the remaining issues surrounding Wnt proteins and their interactions. Here we describe the process of maturation of Wnt from its initial translation to its eventual release from a cell and interactions in the extracellular environment.
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Affiliation(s)
- Karl Willert
- Department of Cellular and Molecular Medicine, University of California, San Diego, California 92093, USA.
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80
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Queiroz KCS, Spek CA, Peppelenbosch MP. Targeting Hedgehog signaling and understanding refractory response to treatment with Hedgehog pathway inhibitors. Drug Resist Updat 2012; 15:211-22. [PMID: 22910179 DOI: 10.1016/j.drup.2012.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 12/01/2022]
Abstract
Hedgehog (Hh) signaling is a principal component of the morphogenetic code best known to direct pattern formation during embryogenesis. The Hh pathway remains active in adulthood however where it guides tissue regeneration and remodeling and Hh production in the niche plays an important role in maintaining stem cell compartment size. Deregulated Hh signaling activity is associated, depending on the context, with both cancer initiation and progression. Interestingly, the Hh pathway is remarkably druggable, raising hopes that inhibition of the pathway could support anticancer therapy. Indeed, a large body of preclinical data supports such an action, but promising clinical data are still limited to basal cell carcinoma (BSC) and medulloblastoma. Nevertheless cancer resistance against Hh targeting has already emerged as a major problem. Here we shall review the current situation with respect to targeting the Hh pathway in cancer in general and in chemotolerance in particular with a focus on the problems associated with the emergence of tumors resistant to treatment with inhibitors targeting the Hh receptor Smoothened (SMO).
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Affiliation(s)
- Karla C S Queiroz
- Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
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81
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Chen J, Honeyager SM, Schleede J, Avanesov A, Laughon A, Blair SS. Crossveinless d is a vitellogenin-like lipoprotein that binds BMPs and HSPGs, and is required for normal BMP signaling in the Drosophila wing. Development 2012; 139:2170-6. [PMID: 22573617 DOI: 10.1242/dev.073817] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The sensitivity of the posterior crossvein in the pupal wing of Drosophila to reductions in the levels and range of BMP signaling has been used to isolate and characterize novel regulators of this pathway. We show here that crossveinless d (cv-d) mutations, which disrupt BMP signaling during the development of the posterior crossvein, mutate a lipoprotein that is similar to the vitellogenins that comprise the major constituents of yolk in animal embryos. Cv-d is made in the liver-like fat body and other tissues, and can diffuse into the pupal wing via the hemolymph. Cv-d binds to the BMPs Dpp and Gbb through its Vg domain, and to heparan sulfate proteoglycans, which are well-known for their role in BMP movement and accumulation in the wing. Cv-d acts over a long range in vivo, and does not have BMP co-receptor-like activity in vitro. We suggest that, instead, it affects the range of BMP movement in the pupal wing, probably as part of a lipid-BMP-lipoprotein complex, similar to the role proposed for the apolipophorin lipid transport proteins in Hedgehog and Wnt movement.
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Affiliation(s)
- Jun Chen
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA
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82
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Zhou S, Lo WC, Suhalim JL, Digman MA, Gratton E, Nie Q, Lander AD. Free extracellular diffusion creates the Dpp morphogen gradient of the Drosophila wing disc. Curr Biol 2012; 22:668-75. [PMID: 22445299 DOI: 10.1016/j.cub.2012.02.065] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 01/09/2012] [Accepted: 02/28/2012] [Indexed: 12/27/2022]
Abstract
BACKGROUND How morphogen gradients form has long been a subject of controversy. The strongest support for the view that morphogens do not simply spread by free diffusion has come from a variety of studies of the Decapentaplegic (Dpp) gradient of the Drosophila larval wing disc. RESULTS In the present study, we initially show how the failure, in such studies, to consider the coupling of transport to receptor-mediated uptake and degradation has led to estimates of transport rates that are orders of magnitude too low, lending unwarranted support to a variety of hypothetical mechanisms, such as "planar transcytosis" and "restricted extracellular diffusion." Using several independent dynamic methods, we obtain data that are inconsistent with such models and show directly that Dpp transport occurs by simple, rapid diffusion in the extracellular space. We discuss the implications of these findings for other morphogen systems in which complex transport mechanisms have been proposed. CONCLUSIONS We believe that these findings resolve a major, longstanding question about morphogen gradient formation and provide a solid framework for interpreting experimental observations of morphogen gradient dynamics.
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Affiliation(s)
- Shaohua Zhou
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
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83
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Kikuchi A, Yamamoto H, Sato A, Matsumoto S. New insights into the mechanism of Wnt signaling pathway activation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 291:21-71. [PMID: 22017973 DOI: 10.1016/b978-0-12-386035-4.00002-1] [Citation(s) in RCA: 203] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Wnts compromise a large family of secreted, hydrophobic glycoproteins that control a variety of developmental and adult processes in all metazoan organisms. Recent advances in the Wnt-signal studies have revealed that distinct Wnts activate multiple intracellular cascades that regulate cellular proliferation, differentiation, migration, and polarity. Although the mechanism by which Wnts regulate different pathways selectively remains to be clarified, evidence has accumulated that in addition to the formation of ligand-receptor pairs, phosphorylation of receptors, receptor-mediated endocytosis, acidification, and the presence of cofactors, such as heparan sulfate proteoglycans, are also involved in the activation of specific Wnt pathways. Here, we review the mechanism of activation in Wnt signaling initiated on the cell-surface membrane. In addition, the mechanisms for fine-tuning by cross talk between Wnt and other signaling are also discussed.
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Affiliation(s)
- Akira Kikuchi
- Department of Biochemistry, Graduate School of Medicine, Osaka University, Osaka, Japan
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84
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The role of glypicans in Wnt inhibitory factor-1 activity and the structural basis of Wif1's effects on Wnt and Hedgehog signaling. PLoS Genet 2012; 8:e1002503. [PMID: 22383891 PMCID: PMC3285576 DOI: 10.1371/journal.pgen.1002503] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 12/11/2011] [Indexed: 01/03/2023] Open
Abstract
Proper assignment of cellular fates relies on correct interpretation of Wnt and Hedgehog (Hh) signals. Members of the Wnt Inhibitory Factor-1 (WIF1) family are secreted modulators of these extracellular signaling pathways. Vertebrate WIF1 binds Wnts and inhibits their signaling, but its Drosophila melanogaster ortholog Shifted (Shf) binds Hh and extends the range of Hh activity in the developing D. melanogaster wing. Shf activity is thought to depend on reinforcing interactions between Hh and glypican HSPGs. Using zebrafish embryos and the heterologous system provided by D. melanogaster wing, we report on the contribution of glypican HSPGs to the Wnt-inhibiting activity of zebrafish Wif1 and on the protein domains responsible for the differences in Wif1 and Shf specificity. We show that Wif1 strengthens interactions between Wnt and glypicans, modulating the biphasic action of glypicans towards Wnt inhibition; conversely, glypicans and the glypican-binding “EGF-like” domains of Wif1 are required for Wif1's full Wnt-inhibiting activity. Chimeric constructs between Wif1 and Shf were used to investigate their specificities for Wnt and Hh signaling. Full Wnt inhibition required the “WIF” domain of Wif1, and the HSPG-binding EGF-like domains of either Wif1 or Shf. Full promotion of Hh signaling requires both the EGF-like domains of Shf and the WIF domains of either Wif1 or Shf. That the Wif1 WIF domain can increase the Hh promoting activity of Shf's EGF domains suggests it is capable of interacting with Hh. In fact, full-length Wif1 affected distribution and signaling of Hh in D. melanogaster, albeit weakly, suggesting a possible role for Wif1 as a modulator of vertebrate Hh signaling. In developing organisms, cells choose between alternative fates in order to make appropriately patterned tissues, and misregulation of those choices can underlie both developmental defects and cancers. Cells often make these decisions because of signals received from neighboring cells, such as those mediated by the secreted signaling proteins of the Wnt and Hedgehog (Hh) families. While signaling can be regulated by the levels of signaling or receptor proteins expressed by cells, another level of control is exerted by proteins that bind signaling proteins outside of cells and either inhibit or promote the signaling process. In the fruitfly Drosophilamelanogaster, the secreted Shifted protein has been shown to bind Hh and to increase Hh signaling, likely by reinforcing interactions between Hh and cell surface proteins of the glypican family. We provide evidence that the vertebrate homolog of Shifted, Wnt Inhibitory Factor-1 (Wif1), inhibits Wnt activity by a similar mechanism, reinforcing interactions between Wnts and glypicans in a manner that sequesters Wnts from their receptors. We also examine the structural basis for the specificities of Wif1 and Shifted for Wnt and Hh signaling, respectively, and provide evidence that Wif1, although a potent inhibitor of Wnt activity, influences D. melanogaster Hh signaling.
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Jennes I, Zuntini M, Mees K, Palagani A, Pedrini E, De Cock G, Fransen E, Vanden Berghe W, Sangiorgi L, Wuyts W. Identification and functional characterization of the human EXT1 promoter region. Gene 2011; 492:148-59. [PMID: 22037484 DOI: 10.1016/j.gene.2011.10.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 10/02/2011] [Accepted: 10/11/2011] [Indexed: 01/02/2023]
Abstract
BACKGROUND Mutations in Exostosin-1 (EXT1) or Exostosin-2 (EXT2) cause the autosomal dominant disorder multiple osteochondromas (MO). This disease is mainly characterized by the appearance of multiple cartilage-capped protuberances arising from children's metaphyses and is known to display clinical inter- and intrafamilial variations. EXT1 and EXT2 are both tumor suppressor genes encoding proteins that function as glycosyltransferases, catalyzing the biosynthesis of heparan sulfate. At present, however, very little is known about the regulation of these genes. Two of the most intriguing questions concerning the pathogenesis of MO are how disruption of a ubiquitously expressed gene causes this cartilage-specific disease and how the clinical intrafamilial variation can be explained. Since mutations in the EXT1 gene are responsible for ~65% of the MO families with known causal mutation, our aim was to isolate and characterize the EXT1 promoter region to elucidate the transcriptional regulation of this tumor suppressor gene. METHODS In the present study, luciferase reporter gene assays were used to experimentally confirm the in silico predicted EXT1 core promoter region. Subsequently, we evaluated the effect of single nucleotide polymorphisms (SNP's) on EXT1 promoter activity and transcription factor binding using luciferase assays, electrophoretic mobility shift assays (EMSA), and enzyme-linked immunosorbent assays (ELISA). Finally, a genotype-phenotype study was performed with the aim to identify one or more genetic modifiers influencing the clinical expression of MO. RESULTS Transient transfection of HEK293 cells with a series of luciferase reporter constructs mapped the EXT1 core promoter at approximately -917 bp upstream of the EXT1 start codon, within a 123 bp region. This region is conserved in mammals and located within a CpG-island containing a CAAT- and a GT-box. A polymorphic G/C-SNP at -1158 bp (rs34016643) was demonstrated to be located in a USF1 transcription factor binding site, which is lost with the presence of the C-allele resulting in a ~56% increase in EXT1 promoter activity. A genotype-phenotype study was suggestive for association of the C-allele with shorter stature, but also with a smaller number of osteochondromas. CONCLUSIONS We provide for the first time insight into the molecular regulation of EXT1. Although a larger patient population will be necessary for statistical significance, our data suggest the polymorphism rs34016643, in close proximity of the EXT1 promoter, to be a potential regulatory SNP, which could be a primary modifier that might explain part of the clinical variation observed in MO patients.
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Affiliation(s)
- Ivy Jennes
- Department of Medical Genetics, University of Antwerp, and Antwerp University Hospital, Edegem, Belgium
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86
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Kawamori H, Tai M, Sato M, Yasugi T, Tabata T. Fat/Hippo pathway regulates the progress of neural differentiation signaling in the Drosophila optic lobe. Dev Growth Differ 2011; 53:653-67. [PMID: 21671914 DOI: 10.1111/j.1440-169x.2011.01279.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A large number of neural and glial cell species differentiate from neuronal precursor cells during nervous system development. Two types of Drosophila optic lobe neurons, lamina and medulla neurons, are derived from the neuroepithelial (NE) cells of the outer optic anlagen. During larval development, epidermal growth factor receptor (EGFR)/Ras signaling sweeps the NE field from the medial edge and drives medulla neuroblast (NB) formation. This signal drives the transient expression of a proneural gene, lethal of scute, and we refer to its signal array as the "proneural wave," as it is the marker of the EGFR/Ras signaling front. In this study, we show that the atypical cadherin Fat and the downstream Hippo pathways regulate the transduction of EGFR/Ras signaling along the NE field and, thus, ensure the progress of NB differentiation. Fat/Hippo pathway mutation also disrupts the pattern formation of the medulla structure, which is associated with the regulation of neurogenesis. A candidate for the Fat ligand, Dachsous is expressed in the posterior optic lobe, and its mutation was observed to cause a similar phenotype as fat mutation, although in a regionally restricted manner. We also show that Dachsous functions as the ligand in this pathway and genetically interacts with Fat in the optic lobe. These findings provide new insights into the function of the Fat/Hippo pathway, which regulates the ordered progression of neurogenesis in the complex nervous system.
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Affiliation(s)
- Haruhiko Kawamori
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku Tokyo 113-0032, Japan
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87
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Mii Y, Taira M. Secreted Wnt "inhibitors" are not just inhibitors: regulation of extracellular Wnt by secreted Frizzled-related proteins. Dev Growth Differ 2011; 53:911-23. [PMID: 21995331 DOI: 10.1111/j.1440-169x.2011.01299.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Gradient formation and signaling ranges of secreted proteins are crucial problems to understand how morphogens work for positional information and patterning in animal development. Yet, extracellular behaviors of secreted signaling molecules remain unexplored compared to their downstream pathways inside the cell. Recent advances in bioimaging make it possible to directly visualize morphogen molecules, and this simple strategy has, at least partly, succeeded in uncovering molecular behaviors of morphogens, such as Wnt (wingless-type MMTV integration site family member) and BMP (bone morphogenetic protein) as well as secreted Wnt binding proteins, sFRPs (secreted Frizzled-related proteins), in embryonic tissues. Here, we review the regulation of Wnt signaling by sFRPs, focusing on extracellular regulation of Wnt ligands in comparison with other morphogens. We also discuss evolutionary aspects with comprehensive syntenic and phylogenetic information about vertebrate sfrp genes. We newly annotated several sfrp genes including sfrp2-like 1 (sfrp2l1) in frogs and fishes and crescent in mammals.
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Affiliation(s)
- Yusuke Mii
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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88
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Shimokawa K, Kimura-Yoshida C, Nagai N, Mukai K, Matsubara K, Watanabe H, Matsuda Y, Mochida K, Matsuo I. Cell surface heparan sulfate chains regulate local reception of FGF signaling in the mouse embryo. Dev Cell 2011; 21:257-72. [PMID: 21839920 DOI: 10.1016/j.devcel.2011.06.027] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 04/11/2011] [Accepted: 06/24/2011] [Indexed: 11/24/2022]
Abstract
Heparan sulfate (HS) proteoglycans modulate the activity of multiple growth factors on the cell surface and extracellular matrix. However, it remains unclear how the HS chains control the movement and reception of growth factors into targeted receiving cells during mammalian morphogenetic processes. Here, we found that HS-deficient Ext2 null mutant mouse embryos fail to respond to fibroblast growth factor (FGF) signaling. Marker expression analyses revealed that cell surface-tethered HS chains are crucial for local retention of FGF4 and FGF8 ligands in the extraembryonic ectoderm. Fine chimeric studies with single-cell resolution and expression studies with specific inhibitors for HS movement demonstrated that proteolytic cleavage of HS chains can spread FGF signaling to adjacent cells within a short distance. Together, the results show that spatiotemporal expression of cell surface-tethered HS chains regulate the local reception of FGF-signaling activity during mammalian embryogenesis.
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Affiliation(s)
- Kayo Shimokawa
- Department of Molecular Embryology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan
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89
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Abstract
Extracellular signaling molecules have crucial roles in development and homeostasis, and their incorrect deployment can lead to developmental defects and disease states. Signaling molecules are released from sending cells, travel to target cells, and act over length scales of several orders of magnitude, from morphogen-mediated patterning of small developmental fields to hormonal signaling throughout the organism. We discuss how signals are modified and assembled for transport, which routes they take to reach their targets, and how their range is affected by mobility and stability.
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Affiliation(s)
- Patrick Müller
- Department of Molecular and Cellular Biology, Harvard Stem Cell Institute, Broad Institute, Center for Brain Science, FAS Center for Systems Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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90
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Abstract
Morphogens are long-range signaling molecules that pattern developing tissues in a concentration-dependent manner. The graded activity of morphogens within tissues exposes cells to different signal levels and leads to region-specific transcriptional responses and cell fates. In its simplest incarnation, a morphogen signal forms a gradient by diffusion from a local source and clearance in surrounding tissues. Responding cells often transduce morphogen levels in a linear fashion, which results in the graded activation of transcriptional effectors. The concentration-dependent expression of morphogen target genes is achieved by their different binding affinities for transcriptional effectors as well as inputs from other transcriptional regulators. Morphogen distribution and interpretation are the result of complex interactions between the morphogen and responding tissues. The response to a morphogen is dependent not simply on morphogen concentration but also on the duration of morphogen exposure and the state of the target cells. In this review, we describe the morphogen concept and discuss the mechanisms that underlie the generation, modulation, and interpretation of morphogen gradients.
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Affiliation(s)
- Katherine W Rogers
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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91
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Malinauskas T, Aricescu AR, Lu W, Siebold C, Jones EY. Modular mechanism of Wnt signaling inhibition by Wnt inhibitory factor 1. Nat Struct Mol Biol 2011; 18:886-93. [PMID: 21743455 DOI: 10.1038/nsmb.2081] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 05/06/2011] [Indexed: 01/12/2023]
Abstract
Wnt morphogens control embryonic development and homeostasis in adult tissues. In vertebrates the N-terminal WIF domain (WIF-1(WD)) of Wnt inhibitory factor 1 (WIF-1) binds Wnt ligands. Our crystal structure of WIF-1(WD) reveals a previously unidentified binding site for phospholipid; two acyl chains extend deep into the domain, and the head group is exposed to the surface. Biophysical and cellular assays indicate that there is a WIF-1(WD) Wnt-binding surface proximal to the lipid head group but also implicate the five epidermal growth factor (EGF)-like domains (EGFs I-V) in Wnt binding. The six-domain WIF-1 crystal structure shows that EGFs I-V are wrapped back, interfacing with WIF-1(WD) at EGF III. EGFs II-V contain a heparan sulfate proteoglycan (HSPG)-binding site, consistent with conserved positively charged residues on EGF IV. This combination of HSPG- and Wnt-binding properties suggests a modular model for the localization of WIF-1 and for signal inhibition within morphogen gradients.
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Affiliation(s)
- Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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92
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Su Y, Ospina JK, Zhang J, Michelson AP, Schoen AM, Zhu AJ. Sequential phosphorylation of smoothened transduces graded hedgehog signaling. Sci Signal 2011; 4:ra43. [PMID: 21730325 PMCID: PMC3526344 DOI: 10.1126/scisignal.2001747] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The correct interpretation of a gradient of the morphogen Hedgehog (Hh) during development requires phosphorylation of the Hh signaling activator Smoothened (Smo); however, the molecular mechanism by which Smo transduces graded Hh signaling is not well understood. We show that regulation of the phosphorylation status of Smo by distinct phosphatases at specific phosphorylated residues creates differential thresholds of Hh signaling. Phosphorylation of Smo was initiated by adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) and further enhanced by casein kinase I (CKI). We found that protein phosphatase 1 (PP1) directly dephosphorylated PKA-phosphorylated Smo to reduce signaling mediated by intermediate concentrations of Hh, whereas PP2A specifically dephosphorylated PKA-primed, CKI-phosphorylated Smo to restrict signaling by high concentrations of Hh. We also established a functional link between sequentially phosphorylated Smo species and graded Hh activity. Thus, we propose a sequential phosphorylation model in which precise interpretation of morphogen concentration can be achieved upon versatile phosphatase-mediated regulation of the phosphorylation status of an essential activator in developmental signaling.
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Affiliation(s)
| | | | | | - Andrew P. Michelson
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Adam M. Schoen
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Alan Jian Zhu
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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Glycosaminoglycan binding facilitates entry of a bacterial pathogen into central nervous systems. PLoS Pathog 2011; 7:e1002082. [PMID: 21731486 PMCID: PMC3121876 DOI: 10.1371/journal.ppat.1002082] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 04/11/2011] [Indexed: 11/26/2022] Open
Abstract
Certain microbes invade brain microvascular endothelial cells (BMECs) to breach the blood-brain barrier (BBB) and establish central nervous system (CNS) infection. Here we use the leading meningitis pathogen group B Streptococcus (GBS) together with insect and mammalian infection models to probe a potential role of glycosaminoglycan (GAG) interactions in the pathogenesis of CNS entry. Site-directed mutagenesis of a GAG-binding domain of the surface GBS alpha C protein impeded GBS penetration of the Drosophila BBB in vivo and diminished GBS adherence to and invasion of human BMECs in vitro. Conversely, genetic impairment of GAG expression in flies or mice reduced GBS dissemination into the brain. These complementary approaches identify a role for bacterial-GAG interactions in the pathogenesis of CNS infection. Our results also highlight how the simpler yet genetically conserved Drosophila GAG pathways can provide a model organism to screen candidate molecules that can interrupt pathogen-GAG interactions for future therapeutic applications. Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of meningitis in human newborn infants. The bacterial and host factors that allow this pathogen to cross the blood-brain barrier (BBB) and cause central nervous system (CNS) infection are not well understood. Here we demonstrate that GBS expresses a specific protein on its surface that can bind to sugar molecules known as glycosaminoglycans (GAGs) on the surface of brain capillary cells, initiating infection of the BBB. Fruit flies or mice genetically engineered to have reduced GAGs showed decreased dissemination of GBS into the brain tissues following experimental infection. Our results identify a role for bacterial-GAG interactions in the pathogenesis of newborn meningitis and highlight how the simpler yet genetically conserved fruit fly GAG biosynthetic pathways make the fruit fly a good model organism to screen candidate molecules that can interrupt pathogen-GAG interactions for future therapeutic applications.
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94
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Dispatched mediates Hedgehog basolateral release to form the long-range morphogenetic gradient in the Drosophila wing disk epithelium. Proc Natl Acad Sci U S A 2011; 108:12591-8. [PMID: 21690386 DOI: 10.1073/pnas.1106881108] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hedgehog (Hh) moves from the producing cells to regulate the growth and development of distant cells in a variety of tissues. Here, we have investigated the mechanism of Hh release from the producing cells to form a morphogenetic gradient in the Drosophila wing imaginal disk epithelium. We describe that Hh reaches both apical and basolateral plasma membranes, but the apical Hh is subsequently internalized in the producing cells and routed to the basolateral surface, where Hh is released to form a long-range gradient. Functional analysis of the 12-transmembrane protein Dispatched, the glypican Dally-like (Dlp) protein, and the Ig-like and FNNIII domains of protein Interference Hh (Ihog) revealed that Dispatched could be involved in the regulation of vesicular trafficking necessary for basolateral release of Hh, Dlp, and Ihog. We also show that Dlp is needed in Hh-producing cells to allow for Hh release and that Ihog, which has been previously described as an Hh coreceptor, anchors Hh to the basolateral part of the disk epithelium.
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95
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The Wnt5/planar cell polarity pathway regulates axonal development of the Drosophila mushroom body neuron. J Neurosci 2011; 31:4944-54. [PMID: 21451033 DOI: 10.1523/jneurosci.0154-11.2011] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Axonal development is a fundamental process for circuit formation in the nervous system and is dependent on many cellular events, including axon initiation, elongation, guidance, and branching. The molecular mechanisms underlying these events have been well studied, especially for axon guidance. In the presence of a guidance cue, the polarization of a growth cone precedes the turning response, which is one example of the diverse forms of cell polarity. Planar cell polarity (PCP) is another example of cell polarity. Although some PCP genes are required for axonal tract formation in vertebrates, it remains elusive whether these genes participate in a common PCP pathway concertedly. Here, we show that essential PCP signaling components, encoded by frizzled (fz), strabismus (stbm), flamingo (fmi), and dishevelled (dsh), are cooperatively required for axonal targeting and branching of the Drosophila mushroom body (MB) neurons. A detailed analysis of these mutants revealed that these components were required for the correct targeting and bifurcation of axons. In addition, we suggest that Wnt5 functions as a ligand in the PCP pathway in this process. Wnt5 mutants showed similar phenotypes to PCP mutants at the single-cell level and genetically interacted with PCP genes. Wnt5 was broadly expressed in the developing brain. We propose that Wnt5 and the PCP pathway concertedly regulate axonal development of the MB.
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96
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Shah MM, Sakurai H, Gallegos TF, Sweeney DE, Bush KT, Esko JD, Nigam SK. Growth factor-dependent branching of the ureteric bud is modulated by selective 6-O sulfation of heparan sulfate. Dev Biol 2011; 356:19-27. [PMID: 21600196 DOI: 10.1016/j.ydbio.2011.05.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 11/24/2022]
Abstract
Heparan sulfate proteoglycans (HSPGs) are found in the basement membrane and at the cell-surface where they modulate the binding and activity of a variety of growth factors and other molecules. Most of the functions of HSPGs are mediated by the variable sulfated glycosaminoglycan (GAG) chains attached to a core protein. Sulfation of the GAG chain is key as evidenced by the renal agenesis phenotype in mice deficient in the HS biosynthetic enzyme, heparan sulfate 2-O sulfotransferase (Hs2st; an enzyme which catalyzes the 2-O-sulfation of uronic acids in heparan sulfate). We have recently demonstrated that this phenotype is likely due to a defect in induction of the metanephric mesenchyme (MM), which along with the ureteric bud (UB), is responsible for the mutually inductive interactions in the developing kidney (Shah et al., 2010). Here, we sought to elucidate the role of variable HS sulfation in UB branching morphogenesis, particularly the role of 6-O sulfation. Endogenous HS was localized along the length of the UB suggesting a role in limiting growth factors and other molecules to specific regions of the UB. Treatment of cultures of whole embryonic kidney with variably desulfated heparin compounds indicated a requirement of 6O-sulfation in the growth and branching of the UB. In support of this notion, branching morphogenesis of the isolated UB was found to be more sensitive to the HS 6-O sulfation modification when compared to the 2-O sulfation modification. In addition, a variety of known UB branching morphogens (i.e., pleiotrophin, heregulin, FGF1 and GDNF) were found to have a higher affinity for 6-O sulfated heparin providing additional support for the notion that this HS modification is important for robust UB branching morphogenesis. Taken together with earlier studies, these findings suggest a general mechanism for spatio-temporal HS regulation of growth factor activity along the branching UB and in the developing MM and support the view that specific growth factor-HSPG interactions establish morphogen gradients and function as developmental switches during the stages of epithelial organogenesis (Shah et al., 2004).
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Affiliation(s)
- Mita M Shah
- Department of Medicine (Division of Nephrology and Hypertension), University of California, San Diego, La Jolla, California 92093, USA
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97
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Ma G, Yu J, Xiao Y, Chan D, Gao B, Hu J, He Y, Guo S, Zhou J, Zhang L, Gao L, Zhang W, Kang Y, Cheah KSE, Feng G, Guo X, Wang Y, Zhou CZ, He L. Indian hedgehog mutations causing brachydactyly type A1 impair Hedgehog signal transduction at multiple levels. Cell Res 2011; 21:1343-57. [PMID: 21537345 DOI: 10.1038/cr.2011.76] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Brachydactyly type A1 (BDA1), the first recorded Mendelian autosomal dominant disorder in humans, is characterized by a shortening or absence of the middle phalanges. Heterozygous missense mutations in the Indian Hedgehog (IHH) gene have been identified as a cause of BDA1; however, the biochemical consequences of these mutations are unclear. In this paper, we analyzed three BDA1 mutations (E95K, D100E, and E131K) in the N-terminal fragment of Indian Hedgehog (IhhN). Structural analysis showed that the E95K mutation changes a negatively charged area to a positively charged area in a calcium-binding groove, and that the D100E mutation changes the local tertiary structure. Furthermore, we showed that the E95K and D100E mutations led to a temperature-sensitive and calcium-dependent instability of IhhN, which might contribute to an enhanced intracellular degradation of the mutant proteins via the lysosome. Notably, all three mutations affected Hh binding to the receptor Patched1 (PTC1), reducing its capacity to induce cellular differentiation. We propose that these are common features of the mutations that cause BDA1, affecting the Hh tertiary structure, intracellular fate, binding to the receptor/partners, and binding to extracellular components. The combination of these features alters signaling capacity and range, but the impact is likely to be variable and mutation-dependent. The potential variation in the signaling range is characterized by an enhanced interaction with heparan sulfate for IHH with the E95K mutation, but not the E131K mutation. Taken together, our results suggest that these IHH mutations affect Hh signaling at multiple levels, causing abnormal bone development and abnormal digit formation.
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Affiliation(s)
- Gang Ma
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030, China
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Zak BM, Schuksz M, Koyama E, Mundy C, Wells DE, Yamaguchi Y, Pacifici M, Esko JD. Compound heterozygous loss of Ext1 and Ext2 is sufficient for formation of multiple exostoses in mouse ribs and long bones. Bone 2011; 48:979-87. [PMID: 21310272 PMCID: PMC3335264 DOI: 10.1016/j.bone.2011.02.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 01/29/2011] [Accepted: 02/01/2011] [Indexed: 12/27/2022]
Abstract
Multiple Hereditary Exostoses (MHE) syndrome is caused by haploinsufficiency in Golgi-associated heparan sulfate polymerases EXT1 or EXT2 and is characterized by formation of exostoses next to growing long bones and other skeletal elements. Recent mouse studies have indicated that formation of stereotypic exostoses requires a complete loss of Ext expression, suggesting that a similar local loss of EXT function may underlie exostosis formation in patients. To further test this possibility and gain greater insights into pathogenic mechanisms, we created heterozygous Ext1(+/-) and compound Ext1(+/-)/Ext2(+/-) mice. Like Ext2(+/-) mice described previously (Stickens et al. Development 132:5055), Ext1(+/-) mice displayed rib-associated exostosis-like outgrowths only. However, compound heterozygous mice had nearly twice as many outgrowths and, more importantly, displayed stereotypic growth plate-like exostoses along their long bones. Ext1(+/-)Ext2(+/-) exostoses contained very low levels of immuno-detectable heparan sulfate, and Ext1(+/-)Ext2(+/-) chondrocytes, endothelial cells and fibroblasts in vitro produced shortened heparan sulfate chains compared to controls and responded less vigorously to exogenous factors such as FGF-18. We also found that rib outgrowths formed in Ext1(f/+)Col2Cre and Ext1(f/+)Dermo1Cre mice, suggesting that ectopic skeletal tissue can be induced by conditional Ext ablation in local chondrogenic and/or perichondrial cells. The study indicates that formation of stereotypic exostoses requires a significant, but not complete, loss of Ext expression and that exostosis incidence and phenotype are intimately sensitive to, and inversely related to, Ext expression. The data also indicate that the nature and organization of ectopic tissue may be influenced by site-specific anatomical cues and mechanisms.
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Affiliation(s)
- Beverly M Zak
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA.
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Zuntini M, Salvatore M, Pedrini E, Parra A, Sgariglia F, Magrelli A, Taruscio D, Sangiorgi L. MicroRNA profiling of multiple osteochondromas: identification of disease-specific and normal cartilage signatures. Clin Genet 2011; 78:507-16. [PMID: 20662852 DOI: 10.1111/j.1399-0004.2010.01490.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Multiple osteochondroma (MO) is a rare skeletal disease characterized by the formation of multiple benign cartilage-capped bone tumors; in 1-5% of patients, a malignant transformation into peripheral chondrosarcoma may occur. This disorder is characterized by a large spectrum of germline mutations scattered along EXT1/EXT2 genes, the presence of a significant percentage of patients without alterations in EXT genes, and a large phenotypic variability. The molecular basis of MO genetic and clinical heterogeneity, including the causes underlying malignant transformation, is currently unknown. This leads to the lack of appropriate diagnostic/prognostic markers as well as of therapeutic options. Recently, specific microRNAs (miRNAs) were reported to be involved in chondrogenesis and inflammatory cartilage diseases. We therefore hypothesized a role for microRNAs in cartilaginous tumors and investigated microRNA expression in osteochondroma and normal cartilage tissues to evaluate whether they could affect osteochondromas onset and/or clinical manifestations. Our results indicate that miRNAs differentially expressed in MO samples may hamper the molecular signaling responsible for normal differentiation of chondrocytes, contributing to pathogenesis and clinical outcome. Although further studies are needed to validate our observations and to identify targets of miRNAs, this is the first study reporting on miRNA expression in growth plate and its comparison with pathological conditions.
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Affiliation(s)
- M Zuntini
- Department of Medical Genetics and Skeletal Rare Diseases, Rizzoli Orthopaedic Institute, 40136 Bologna, Italy
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Nadanaka S, Kinouchi H, Taniguchi-Morita K, Tamura JI, Kitagawa H. Down-regulation of chondroitin 4-O-sulfotransferase-1 by Wnt signaling triggers diffusion of Wnt-3a. J Biol Chem 2011; 286:4199-208. [PMID: 21123170 PMCID: PMC3039320 DOI: 10.1074/jbc.m110.155093] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 10/28/2010] [Indexed: 11/06/2022] Open
Abstract
During metazoan development, Wnt molecules are secreted from Wnt-producing cells, diffuse to target cells, and determine cell fates; therefore, Wnt secretion is tightly regulated. However, the molecular mechanisms controlling Wnt diffusion are not fully elucidated. The specific chondroitin sulfate (CS) structure synthesized by chondroitin-4-O-sulfotransferase-1 (C4ST-1) binds to Wnt-3a with high affinity (Nadanaka, S., Ishida, M., Ikegami, M., and Kitagawa, H. (2008) J. Biol. Chem. 283, 27333-27343). In this study we tested whether Wnt signaling regulates sulfation patterns of cell-associated CS chains by suppressing expression of C4ST-1 to trigger release of Wnt molecules from Wnt-producing cells. C4ST-1 expression was dramatically reduced in L cells that stably expressed Wnt-3a (L-Wnt-3a cells) and had CS with low affinity for Wnt-3a. Forced expression of C4ST-1 in L-Wnt-3a cells inhibited diffusion of Wnt-3a due to structural alterations in CS chains mediated by C4ST-1. Furthermore, sustained Wnt signaling negatively regulated C4ST-1 expression in a cell-autonomous and non-cell autonomous fashion. These results demonstrated that C4ST-1 is a key downstream target of Wnt signaling that regulates Wnt diffusion from Wnt-producing cells.
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Affiliation(s)
- Satomi Nadanaka
- From the Department of Biochemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan and
| | - Hiroki Kinouchi
- From the Department of Biochemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan and
| | - Kayo Taniguchi-Morita
- the Department of Regional Environment, Faculty of Regional Sciences, Tottori University, Tottori 680-8551, Japan
| | - Jun-ichi Tamura
- the Department of Regional Environment, Faculty of Regional Sciences, Tottori University, Tottori 680-8551, Japan
| | - Hiroshi Kitagawa
- From the Department of Biochemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan and
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