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Chandler CM, McDougal OM. Medicinal history of North American Veratrum.. PHYTOCHEMISTRY REVIEWS : PROCEEDINGS OF THE PHYTOCHEMICAL SOCIETY OF EUROPE 2014; 13:671-694. [PMID: 25379034 PMCID: PMC4217314 DOI: 10.1007/s11101-013-9328-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plants belonging to the genus Veratrum have been used throughout history for their medicinal properties. During the nineteenth and twentieth centuries, phytochemical investigations revealed a host of steroidal alkaloids in Veratrum species, some of which are potent bioactives. This review discusses Veratrum species that grow in North America with a focus on the medicinal history of these plants and the steroidal alkaloids they contain. While significant reviews have been devoted to singularly describing the plant species within the genus Veratrum (botany), the staggering breadth of alkaloids isolated from these and related plants (phytochemistry), and the intricacies of how the various alkaloids act on their biological targets (physiology and biochemistry), this review will straddle the margins of the aforementioned disciplines in an attempt to provide a unified, coherent picture of the Veratrum plants of North America and the medicinal uses of their bioactive steroidal alkaloids.
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Affiliation(s)
- Christopher M. Chandler
- Department of Chemistry and Biochemistry, Boise State, University, 1910 University Drive, Boise, ID 83725-1520, USA
| | - Owen M. McDougal
- Department of Chemistry and Biochemistry, Boise State, University, 1910 University Drive, Boise, ID 83725-1520, USA
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152
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Alfaro AC, Roberts B, Kwong L, Bijlsma MF, Roelink H. Ptch2 mediates the Shh response in Ptch1-/- cells. Development 2014; 141:3331-9. [PMID: 25085974 DOI: 10.1242/dev.110056] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Hedgehog (Hh) signaling response is regulated by the interaction of three key components that include the sonic hedgehog (Shh) ligand, its receptor patched 1 (Ptch1) and the pathway activator smoothened (Smo). Under the prevailing model of Shh pathway activation, the binding of Shh to Ptch1 (the key Shh receptor) results in the release of Ptch1-mediated inhibition of Smo, leading to Smo activation and subsequent cell-autonomous activation of the Shh response. Consistent with this model, Ptch1(-/-) cells show a strong upregulation of the Shh response. Our finding that this response can be inhibited by the Shh-blocking antibody 5E1 indicates that the Shh response in Ptch1(-/-) cells remains ligand dependent. Furthermore, we find that Shh induces a strong response in Ptch1(-/-);Shh(-/-) cells, and that Ptch1(-/-) fibroblasts retain their ability to migrate towards Shh, demonstrating that Ptch1(-/-) cells remain sensitive to Shh. Expression of a dominant-negative Ptch1 mutant in the developing chick neural tube had no effect on Shh-mediated patterning, but expression of a dominant-negative form of patched 2 (Ptch2) caused an activation of the Shh response. This indicates that, at early developmental stages, Ptch2 functions to suppress Shh signaling. We found that Ptch1(-/-);Ptch2(-/-) cells cannot further activate the Shh response, demonstrating that Ptch2 mediates the response to Shh in the absence of Ptch1.
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Affiliation(s)
- Astrid C Alfaro
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Brock Roberts
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Lina Kwong
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Maarten F Bijlsma
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
| | - Henk Roelink
- Department of Molecular and Cell Biology, 16 Barker Hall, 3204, University of California, Berkeley, CA 94720, USA
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153
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Saita S, Shirane M, Ishitani T, Shimizu N, Nakayama KI. Role of the ANKMY2-FKBP38 axis in regulation of the Sonic hedgehog (Shh) signaling pathway. J Biol Chem 2014; 289:25639-54. [PMID: 25077969 DOI: 10.1074/jbc.m114.558635] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sonic hedgehog (Shh) is a secreted morphogen that controls the patterning and growth of various tissues in the developing vertebrate embryo, including the central nervous system. Ablation of the FK506-binding protein 38 (FKBP38) gene results in activation of the Shh signaling pathway in mouse embryos, but the molecular mechanism by which FKBP38 suppresses Shh signaling has remained unclear. With the use of a proteomics approach, we have now identified ANKMY2, a protein with three ankyrin repeats and a MYND (myeloid, Nervy, and DEAF-1)-type Zn(2+) finger domain, as a molecule that interacts with FKBP38. Co-immunoprecipitation analysis confirmed that endogenous FKBP38 and ANKMY2 interact in the mouse brain. Depletion or overexpression of ANKMY2 resulted in down- and up-regulation of Shh signaling, respectively, in mouse embryonic fibroblasts. Furthermore, combined depletion of both FKBP38 and ANKMY2 attenuated Shh signaling in these cells, suggesting that ANKMY2 acts downstream of FKBP38 to activate the Shh signaling pathway. Targeting of the zebrafish ortholog of mouse Ankmy2 (ankmy2a) in fish embryos with an antisense morpholino oligonucleotide conferred a phenotype reflecting loss of function of the Shh pathway, suggesting that the regulation of Shh signaling by ANKMY2 is conserved between mammals and fish. Our findings thus indicate that the FKBP38-ANKMY2 axis plays a key role in regulation of Shh signaling in vivo.
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Affiliation(s)
| | | | - Tohru Ishitani
- Division of Cell Regulation Systems, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Nobuyuki Shimizu
- Division of Cell Regulation Systems, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
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154
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He P, Staufenbiel M, Li R, Shen Y. Deficiency of patched 1-induced Gli1 signal transduction results in astrogenesis in Swedish mutated APP transgenic mice. Hum Mol Genet 2014; 23:6512-27. [PMID: 25027328 DOI: 10.1093/hmg/ddu370] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Normally, sonic hedgehog (Shh) signaling induces high levels of Patched 1 (Ptc1) and its associated transcription factor Gli1 with genesis of specific neuronal progeny. But their roles in the neural stem cells (NSCs), including glial precursor cells (GPCs), of Alzheimer's disease (AD) are unclear. Here, we show that Ptc1 and Gli1 are significantly deficits in the hippocampus of an aged AD transgenic mouse mode, whereas these two molecules are highly elevated at young ages. Our similar findings in autopsied AD brains validate the discovery in AD mouse models. To examine whether Aβ peptides, which are a main component of the amyloid plaques in AD brains, affected Ptc1-Gli1 signaling, we treated GPCs with Aβ peptides, we found that high dose of Aβ1-42 but not Aβ1-40 significantly decreased Ptc1-Gli1, while Shh itself was elevated in hippocampal NSCs/GPCs. Furthermore, we found that deficits of Ptc1-Gli1 signaling induced NSCs/GPCs into asymmetric division, which results in an increase in the number of dividing cells including transit-amplifying cells and neuroblasts. These precursor cells commit to apoptosis-like death under the toxic conditions. By this way, adult neural precursor cell pool is exhausted and defective neurogenesis happens in AD brains. Our findings suggest that Ptc1-Gli1 signaling deregulation resulting abnormal loss of GPCs may contribute to a cognition decline in AD brains. The novel findings elucidate a new molecular mechanism of adult NSCs/GPCs on neurogenesis and demonstrate a regulatory role for Ptc1-Gli1 in adult neural circuit integrity of the brain.
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Affiliation(s)
- Ping He
- Center for Advanced Therapeutic Strategies for Brain Disorders and
| | | | - Rena Li
- Center for Hormone Advanced Science and Education, The Roskamp Institute, Sarasota, FL 34243, USA,
| | - Yong Shen
- Center for Advanced Therapeutic Strategies for Brain Disorders and, Department of Neurology, University of Florida College of Medicine, Gainesville FL32610, USA
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155
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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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156
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Lopez-Rios J, Duchesne A, Speziale D, Andrey G, Peterson KA, Germann P, Ünal E, Liu J, Floriot S, Barbey S, Gallard Y, Müller-Gerbl M, Courtney AD, Klopp C, Rodriguez S, Ivanek R, Beisel C, Wicking C, Iber D, Robert B, McMahon AP, Duboule D, Zeller R. Attenuated sensing of SHH by Ptch1 underlies evolution of bovine limbs. Nature 2014; 511:46-51. [DOI: 10.1038/nature13289] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/27/2014] [Indexed: 11/09/2022]
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157
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Ejsmont RK, Hassan BA. The Little Fly that Could: Wizardry and Artistry of Drosophila Genomics. Genes (Basel) 2014; 5:385-414. [PMID: 24827974 PMCID: PMC4094939 DOI: 10.3390/genes5020385] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/16/2014] [Accepted: 04/21/2014] [Indexed: 12/30/2022] Open
Abstract
For more than 100 years now, the fruit fly Drosophila melanogaster has been at the forefront of our endeavors to unlock the secrets of the genome. From the pioneering studies of chromosomes and heredity by Morgan and his colleagues, to the generation of fly models for human disease, Drosophila research has been at the forefront of genetics and genomics. We present a broad overview of some of the most powerful genomics tools that keep Drosophila research at the cutting edge of modern biomedical research.
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Affiliation(s)
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, 3000 Leuven, Belgium.
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158
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Roberg-Larsen H, Strand MF, Krauss S, Wilson SR. Metabolites in vertebrate Hedgehog signaling. Biochem Biophys Res Commun 2014; 446:669-74. [DOI: 10.1016/j.bbrc.2014.01.087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 01/18/2014] [Indexed: 12/26/2022]
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159
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Hinterseher U, Wunderlich A, Roth S, Ramaswamy A, Bartsch DK, Hauptmann S, Greene BH, Fendrich V, Hoffmann S. Expression of hedgehog signalling pathway in anaplastic thyroid cancer. Endocrine 2014; 45:439-47. [PMID: 23860623 DOI: 10.1007/s12020-013-0015-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 07/04/2013] [Indexed: 12/26/2022]
Abstract
The purpose of this work is to study the activation of the hedgehog signalling pathway is associated with tumour progression in various types of cancer, hence the development of specific antagonists raises hope for new therapeutic strategies. Therefore, the expression of hedgehog pathway components in anaplastic thyroid cancer (ATC) and effects of the hedgehog inhibitor Cyclopamine on ATC cells were investigated in this study. Expression of the ligand Sonic Hedgehog (SHh), the transmembrane protein Smoothened (Smo), the receptor Patched (Ptc) and the target gene Gli-1 was evaluated in two ATC cell lines (Hth 74, C643) by RT-PCR and in tumour specimens by immunohistochemistry. The corresponding gene products were examined by western blotting analysis. After treatment with different concentrations of Cyclopamine the time-dependent course of cell viability in ATC cell lines was evaluated by MTT assay. SHh, Smo, Ptc and Gli were clearly expressed on mRNA and protein levels in both cell lines and in tumour samples (41 %SHh, 65 %Smo, 65 %Ptc and 65 %Gli). Treatment with Cyclopamine showed a time- and dose-dependent inhibition of cell numbers with IC50 values between 1 and 4 μM in both cell lines, comparable to other types of cancer. In conclusion, we believe that the hedgehog pathway is expressed in anaplastic thyroid carcinoma specimens and proliferation of ATC cell lines can be influenced by the Hh inhibitor Cyclopamine. Aberrant activation of this pathway might be involved in the aggressive biology of anaplastic cancer and further evaluation regarding a possible clinical impact of pathway inhibition is warranted.
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Affiliation(s)
- Ulrike Hinterseher
- Department of Visceral, Thoracic- and Vascular Surgery, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany
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160
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161
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Hedgehog signaling downregulates suppressor of fused through the HIB/SPOP-Crn axis in Drosophila. Cell Res 2014; 24:595-609. [PMID: 24603360 DOI: 10.1038/cr.2014.29] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 11/30/2013] [Accepted: 01/20/2014] [Indexed: 02/07/2023] Open
Abstract
Hedgehog (Hh) signaling plays vital roles in animal development and tissue homeostasis, and its misregulation causes congenital diseases and several types of cancer. Suppressor of Fused (Su(fu)) is a conserved inhibitory component of the Hh signaling pathway, but how it is regulated remains poorly understood. Here we demonstrate that in Drosophila Hh signaling promotes downregulation of Su(fu) through its target protein HIB (Hh-induced BTB protein). Interestingly, although HIB-mediated downregulation of Su(fu) depends on the E3 ubiquitin ligase Cul3, HIB does not directly regulate Su(fu) protein stability. Through an RNAi-based candidate gene screen, we identify the spliceosome factor Crooked neck (Crn) as a regulator of Su(fu) level. Epistasis analysis indicates that HIB downregulates Su(fu) through Crn. Furthermore, we provide evidence that HIB retains Crn in the nucleus, leading to reduced Su(fu) protein level. Finally, we show that SPOP, the mammalian homologue of HIB, can substitute HIB to downregulate Su(fu) level in Drosophila. Our study suggests that Hh regulates both Ci and Su(fu) levels through its target HIB, thus uncovering a novel feedback mechanism that regulates Hh signal transduction. The dual function of HIB may provide a buffering mechanism to fine-tune Hh pathway activity.
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162
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Sherpa T, Lankford T, McGinn TE, Hunter SS, Frey RA, Sun C, Ryan M, Robison BD, Stenkamp DL. Retinal regeneration is facilitated by the presence of surviving neurons. Dev Neurobiol 2014; 74:851-76. [PMID: 24488694 DOI: 10.1002/dneu.22167] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/27/2014] [Accepted: 01/27/2014] [Indexed: 12/22/2022]
Abstract
Teleost fish regenerate their retinas after damage, in contrast to mammals. In zebrafish subjected to an extensive ouabain-induced lesion that destroys all neurons and spares Müller glia, functional recovery and restoration of normal optic nerve head (ONH) diameter take place at 100 days postinjury. Subsequently, regenerated retinas overproduce cells in the retinal ganglion cell (RGC) layer, and the ONH becomes enlarged. Here, we test the hypothesis that a selective injury, which spares photoreceptors and Müller glia, results in faster functional recovery and fewer long-term histological abnormalities. Following this selective retinal damage, recovery of visual function required 60 days, consistent with this hypothesis. In contrast to extensively damaged retinas, selectively damaged retinas showed fewer histological errors and did not overproduce neurons. Extensively damaged retinas had RGC axons that were delayed in pathfinding to the ONH, and showed misrouted axons within the ONH, suggesting that delayed functional recovery following an extensive lesion is related to defects in RGC axons exiting the eye and/or reaching their central targets. The atoh7, fgf8a, Sonic hedgehog (shha), and netrin-1 genes were differentially expressed, and the distribution of hedgehog protein was disrupted after extensive damage as compared with selective damage. Confirming a role for Shh signaling in supporting rapid regeneration, shha(t4) +/- zebrafish showed delayed functional recovery after selective damage. We suggest that surviving retinal neurons provide structural/molecular information to regenerating neurons, and that this patterning mechanism regulates factors such as Shh. These factors in turn control neuronal number, retinal lamination, and RGC axon pathfinding during retinal regeneration.
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Affiliation(s)
- Tshering Sherpa
- Department of Biological Sciences, University of Idaho, Moscow, Idaho; Department of Biological Sciences, Graduate Program in Neuroscience, University of Idaho, Moscow, Idaho
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163
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Hartl TA, Scott MP. Wing tips: The wing disc as a platform for studying Hedgehog signaling. Methods 2014; 68:199-206. [PMID: 24556557 DOI: 10.1016/j.ymeth.2014.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 02/03/2014] [Accepted: 02/06/2014] [Indexed: 12/26/2022] Open
Abstract
Hedgehog (Hh) signal transduction is necessary for the development of most mammalian tissues and can go awry and cause birth defects or cancer. Hh signaling was initially described in Drosophila, and much of what we know today about mammalian Hh signaling was directly guided by discoveries in the fly. Indeed, Hh signaling is a wonderful example of the use of non-vertebrate model organisms to make basic discoveries that lead to new disease treatment. The first pharmaceutical to treat hyperactive Hh signaling in Basal Cell Carcinoma was released in 2012, approximately 30 years after the isolation of Hh mutants in Drosophila. The study of Hh signaling has been greatly facilitated by the imaginal wing disc, a tissue with terrific experimental advantages. Studies using the wing disc have led to an understanding of Hh ligand processing, packaging into particles for transmission, secretion, reception, signal transduction, target gene activation, and tissue patterning. Here we describe the imaginal wing disc, how Hh patterns this tissue, and provide methods to use wing discs to study Hh signaling in Drosophila. The tools and approaches we highlight form the cornerstone of research efforts in many laboratories that use Drosophila to study Hh signaling, and are essential for ongoing discoveries.
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Affiliation(s)
- Tom A Hartl
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Matthew P Scott
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA.
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164
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Saito A, Kanemoto S, Zhang Y, Asada R, Hino K, Imaizumi K. Chondrocyte Proliferation Regulated by Secreted Luminal Domain of ER Stress Transducer BBF2H7/CREB3L2. Mol Cell 2014; 53:127-39. [DOI: 10.1016/j.molcel.2013.11.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/16/2013] [Accepted: 11/08/2013] [Indexed: 01/22/2023]
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165
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Nachtergaele S, Whalen DM, Mydock LK, Zhao Z, Malinauskas T, Krishnan K, Ingham PW, Covey DF, Siebold C, Rohatgi R. Structure and function of the Smoothened extracellular domain in vertebrate Hedgehog signaling. eLife 2013; 2:e01340. [PMID: 24171105 PMCID: PMC3809587 DOI: 10.7554/elife.01340] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/26/2013] [Indexed: 12/14/2022] Open
Abstract
The Hedgehog (Hh) signal is transduced across the membrane by the heptahelical protein Smoothened (Smo), a developmental regulator, oncoprotein and drug target in oncology. We present the 2.3 Å crystal structure of the extracellular cysteine rich domain (CRD) of vertebrate Smo and show that it binds to oxysterols, endogenous lipids that activate Hh signaling. The oxysterol-binding groove in the Smo CRD is analogous to that used by Frizzled 8 to bind to the palmitoleyl group of Wnt ligands and to similar pockets used by other Frizzled-like CRDs to bind hydrophobic ligands. The CRD is required for signaling in response to native Hh ligands, showing that it is an important regulatory module for Smo activation. Indeed, targeting of the Smo CRD by oxysterol-inspired small molecules can block signaling by all known classes of Hh activators and by clinically relevant Smo mutants. DOI:http://dx.doi.org/10.7554/eLife.01340.001.
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MESH Headings
- Animals
- Binding Sites
- Crystallography, X-Ray
- Embryo, Nonmammalian
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Developmental
- Hedgehog Proteins/chemistry
- Hedgehog Proteins/genetics
- Hedgehog Proteins/metabolism
- Ligands
- Mice
- Models, Molecular
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- Smoothened Receptor
- Sterols/chemistry
- Structure-Activity Relationship
- Zebrafish/genetics
- Zebrafish/growth & development
- Zebrafish/metabolism
- Zebrafish Proteins/antagonists & inhibitors
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Sigrid Nachtergaele
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Daniel M Whalen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Laurel K Mydock
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Zhonghua Zhao
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Philip W Ingham
- A*STAR Institute of Molecular and Cell Biology, Singapore, Singapore
- Lee Kong Chian School of Medicine, Imperial College London/Nanyang Technological University, Singapore, Singapore
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Rajat Rohatgi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
- Department of Medicine, Stanford University School of Medicine, Stanford, United States
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166
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PTCH1 gene mutations in Keratocystic odontogenic tumors: a study of 43 Chinese patients and a systematic review. PLoS One 2013; 8:e77305. [PMID: 24204797 PMCID: PMC3804548 DOI: 10.1371/journal.pone.0077305] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 09/04/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The keratocystic odontogenic tumor (KCOT) is a locally aggressive cystic jaw lesion that occurs sporadically or in association with nevoid basal cell carcinoma syndrome (NBCCS). PTCH1, the gene responsible for NBCCS, may play an important role in sporadic KCOTs. In this study, we analyzed and compared the distribution pattern of PTCH1 mutations in patients with sporadic and NBCCS-associated KCOTs. METHODS We detected PTCH1 mutations in 14 patients with NBCCS-associated KCOTs and 29 patients with sporadic KCOTs by direct sequencing. In addition, five electronic databases were searched for studies detecting PTCH1 mutations in individuals with NBCCS-associated or sporadic KCOTs, published between January 1996 and June 2013 in English language. RESULTS We identified 15 mutations in 11 cases with NBCCS-associated KCOTs and 19 mutations in 13 cases with sporadic KCOTs. In addition, a total of 204 PTCH1 mutations (187 mutations from 210 cases with NBCCS-associated and 17 mutations from 57 cases with sporadic KCOTs) were compiled from 78 published papers. CONCLUSIONS Our study indicates that mutations in transmembrane 2 (TM2) are closely related to the development of sporadic KCOTs. Moreover, for the early diagnosis of NBCCS, a genetic analysis of the PTCH1 gene should be included in the new diagnostic criteria.
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167
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Schwend T, Jin Z, Jiang K, Mitchell BJ, Jia J, Yang J. Stabilization of speckle-type POZ protein (Spop) by Daz interacting protein 1 (Dzip1) is essential for Gli turnover and the proper output of Hedgehog signaling. J Biol Chem 2013; 288:32809-32820. [PMID: 24072710 DOI: 10.1074/jbc.m113.512962] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Hedgehog (Hh) pathway is essential for embryonic development and adult tissue homeostasis. The Gli/Cubitus interruptus (Ci) family of transcription factors acts at the downstream end of the pathway to mediate Hh signaling. Both Hh-dependent and -independent Gli regulatory mechanisms are important for the output of Hh signaling. Daz interacting protein 1 (Dzip1) has bipartite positive and negative functions in the Hh pathway. The positive Hh regulatory function appears to be attributed to a requirement for Dzip1 during ciliogenesis. The mechanism by which Dzip1 inhibits Hh signaling, however, remains largely unclear. We recently found that Dzip1 is required for Gli turnover, which may account for its inhibitory function in Hh signaling. Here, we report that Dzip1 regulates Gli/Ci turnover by preventing degradation of speckle-type POZ protein (Spop), a protein that promotes proteasome-dependent turnover of Gli proteins. We provide evidence that Dzip1 regulates the stability of Spop independent of its function in ciliogenesis. Partial knockdown of Dzip1 to levels insufficient for perturbing ciliogenesis, sensitized Xenopus embryos to Hh signaling, leading to phenotypes that resemble activation of Hh signaling. Importantly, overexpression of Spop was able to restore proper Gli protein turnover and rescue phenotypes in Dzip1-depleted embryos. Consistently, depletion of Dzip1 in Drosophila S2 cells destabilized Hh-induced BTB protein (HIB), the Drosophila homolog of Spop, and increased the level of Ci. Thus, Dzip1-dependent stabilization of Spop/HIB is evolutionarily conserved and essential for proper regulation of Gli/Ci proteins in the Hh pathway.
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Affiliation(s)
- Tyler Schwend
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802
| | - Zhigang Jin
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802
| | - Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536-0509
| | - Brian J Mitchell
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536-0509
| | - Jing Yang
- From the Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802,.
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168
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Liu HX, Ermilov A, Grachtchouk M, Li L, Gumucio DL, Dlugosz AA, Mistretta CM. Multiple Shh signaling centers participate in fungiform papilla and taste bud formation and maintenance. Dev Biol 2013; 382:82-97. [PMID: 23916850 DOI: 10.1016/j.ydbio.2013.07.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 07/24/2013] [Accepted: 07/26/2013] [Indexed: 11/17/2022]
Abstract
The adult fungiform taste papilla is a complex of specialized cell types residing in the stratified squamous tongue epithelium. This unique sensory organ includes taste buds, papilla epithelium and lateral walls that extend into underlying connective tissue to surround a core of lamina propria cells. Fungiform papillae must contain long-lived, sustaining or stem cells and short-lived, maintaining or transit amplifying cells that support the papilla and specialized taste buds. Shh signaling has established roles in supporting fungiform induction, development and patterning. However, for a full understanding of how Shh transduced signals act in tongue, papilla and taste bud formation and maintenance, it is necessary to know where and when the Shh ligand and pathway components are positioned. We used immunostaining, in situ hybridization and mouse reporter strains for Shh, Ptch1, Gli1 and Gli2-expression and proliferation markers to identify cells that participate in hedgehog signaling. Whereas there is a progressive restriction in location of Shh ligand-expressing cells, from placode and apical papilla cells to taste bud cells only, a surrounding population of Ptch1 and Gli1 responding cells is maintained in signaling centers throughout papilla and taste bud development and differentiation. The Shh signaling targets are in regions of active cell proliferation. Using genetic-inducible lineage tracing for Gli1-expression, we found that Shh-responding cells contribute not only to maintenance of filiform and fungiform papillae, but also to taste buds. A requirement for normal Shh signaling in fungiform papilla, taste bud and filiform papilla maintenance was shown by Gli2 constitutive activation. We identified proliferation niches where Shh signaling is active and suggest that epithelial and mesenchymal compartments harbor potential stem and/or progenitor cell zones. In all, we report a set of hedgehog signaling centers that regulate development and maintenance of taste organs, the fungiform papilla and taste bud, and surrounding lingual cells. Shh signaling has roles in forming and maintaining fungiform papillae and taste buds, most likely via stage-specific autocrine and/or paracrine mechanisms, and by engaging epithelial/mesenchymal interactions.
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Affiliation(s)
- Hong Xiang Liu
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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169
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Witt RM, Hecht ML, Pazyra-Murphy MF, Cohen SM, Noti C, van Kuppevelt TH, Fuller M, Chan JA, Hopwood JJ, Seeberger PH, Segal RA. Heparan sulfate proteoglycans containing a glypican 5 core and 2-O-sulfo-iduronic acid function as Sonic Hedgehog co-receptors to promote proliferation. J Biol Chem 2013; 288:26275-26288. [PMID: 23867465 DOI: 10.1074/jbc.m112.438937] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sonic Hedgehog (Shh) signaling is crucial for growth, cell fate determination, and axonal guidance in the developing nervous system. Although the receptors Patched (Ptch1) and Smoothened (Smo) are required for Shh signaling, a number of distinct co-receptors contribute to these critical responses to Shh. Several membrane-embedded proteins such as Boc, Cdo, and Gas1 bind Shh and promote signaling. In addition, heparan sulfate proteoglycans (HSPGs) have also been implicated in the initiation of Shh responses. However, the attributes of HSPGs that function as co-receptors for Shh have not yet been defined. Here, we identify HSPGs containing a glypican 5 core protein and 2-O-sulfo-iduronic acid residues at the nonreducing ends of the glycans as co-receptors for Shh. These HSPG co-receptors are expressed by cerebellar granule cell precursors and promote Shh binding and signaling. At the subcellular level, these HSPG co-receptors are located adjacent to the primary cilia that act as Shh signaling organelles. Thus, Shh binds to HSPG co-receptors containing a glypican 5 core and 2-O-sulfo-iduronic acid to promote neural precursor proliferation.
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Affiliation(s)
- Rochelle M Witt
- From the Dana Farber Cancer Institute, Boston, Massachusetts 02215,; the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02215
| | - Marie-Lyn Hecht
- the Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1,14476 Potsdam, Germany,; the Federal Institute of Technology (ETH) Zürich, Wolfgang-Pauli-Str.10, CH-8093 Zürich, Switzerland
| | - Maria F Pazyra-Murphy
- From the Dana Farber Cancer Institute, Boston, Massachusetts 02215,; the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02215
| | - Samuel M Cohen
- From the Dana Farber Cancer Institute, Boston, Massachusetts 02215,; the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02215
| | - Christian Noti
- the Federal Institute of Technology (ETH) Zürich, Wolfgang-Pauli-Str.10, CH-8093 Zürich, Switzerland
| | - Toin H van Kuppevelt
- the Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University, Nijmegen Medical Centre, P. O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Maria Fuller
- the Lysosomal Diseases Research Unit, SA Pathology at Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia
| | - Jennifer A Chan
- the Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada, and
| | - John J Hopwood
- the Lysosomal Diseases Research Unit, SA Pathology at Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia
| | - Peter H Seeberger
- the Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1,14476 Potsdam, Germany,; the Institute of Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany.
| | - Rosalind A Segal
- From the Dana Farber Cancer Institute, Boston, Massachusetts 02215,; the Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02215,.
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170
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Lim CB, Prêle CM, Cheah HM, Cheng YY, Klebe S, Reid G, Watkins DN, Baltic S, Thompson PJ, Mutsaers SE. Mutational analysis of hedgehog signaling pathway genes in human malignant mesothelioma. PLoS One 2013; 8:e66685. [PMID: 23826113 PMCID: PMC3691204 DOI: 10.1371/journal.pone.0066685] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 05/08/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The Hedgehog (HH) signaling pathway is critical for embryonic development and adult homeostasis. Recent studies have identified regulatory roles for this pathway in certain cancers with mutations in the HH pathway genes. The extent to which mutations of the HH pathway genes are involved in the pathogenesis of malignant mesothelioma (MMe) is unknown. METHODOLOGY/PRINCIPAL FINDINGS Real-time PCR analysis of HH pathway genes PTCH1, GLI1 and GLI2 were performed on 7 human MMe cell lines. Exon sequencing of 13 HH pathway genes was also performed in cell lines and human MMe tumors. In silico programs were used to predict the likelihood that an amino-acid substitution would have a functional effect. GLI1, GLI2 and PTCH1 were highly expressed in MMe cells, indicative of active HH signaling. PTCH1, SMO and SUFU mutations were found in 2 of 11 MMe cell lines examined. A non-synonymous missense SUFU mutation (p.T411M) was identified in LO68 cells. In silico characterization of the SUFU mutant suggested that the p.T411M mutation might alter protein function. However, we were unable to demonstrate any functional effect of this mutation on Gli activity. Deletion of exons of the PTCH1 gene was found in JU77 cells, resulting in loss of one of two extracellular loops implicated in HH ligand binding and the intracellular C-terminal domain. A 3-bp insertion (69_70insCTG) in SMO, predicting an additional leucine residue in the signal peptide segment of SMO protein was also identified in LO68 cells and a MMe tumour. CONCLUSIONS/SIGNIFICANCE We identified the first novel mutations in PTCH1, SUFU and SMO associated with MMe. Although HH pathway mutations are relatively rare in MMe, these data suggest a possible role for dysfunctional HH pathway in the pathogenesis of a subgroup of MMe and help rationalize the exploration of HH pathway inhibitors for MMe therapy.
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Affiliation(s)
- Chuan Bian Lim
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
| | - Cecilia M. Prêle
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology and Western Australian Institute for Medical Research, University of Western Australia, Crawley, WA, Australia
| | - Hui Min Cheah
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
| | - Yuen Yee Cheng
- Asbestos Diseases Research Institute (ADRI), University of Sydney, Sydney, NSW, Australia
| | - Sonja Klebe
- Department of Anatomical Pathology, SA Pathology and Flinders University, Flinders Medical Centre, Adelaide, Australia
| | - Glen Reid
- Asbestos Diseases Research Institute (ADRI), University of Sydney, Sydney, NSW, Australia
| | - D. Neil Watkins
- Centre for Cancer Research, Monash Institute for Medical Research, Monash University, Melbourne, Victoria, Australia
| | - Svetlana Baltic
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
| | - Philip J. Thompson
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
| | - Steven E. Mutsaers
- Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Department of Medicine, School of Medicine and Pharmacology, University of Western Australia, Crawley, WA, Australia
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology and Western Australian Institute for Medical Research, University of Western Australia, Crawley, WA, Australia
- * E-mail:
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171
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Wang C, Wu H, Katritch V, Han GW, Huang XP, Liu W, Siu FY, Roth BL, Cherezov V, Stevens RC. Structure of the human smoothened receptor bound to an antitumour agent. Nature 2013; 497:338-43. [PMID: 23636324 DOI: 10.1038/nature12167] [Citation(s) in RCA: 366] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 04/12/2013] [Indexed: 12/15/2022]
Abstract
The smoothened (SMO) receptor, a key signal transducer in the hedgehog signalling pathway, is responsible for the maintenance of normal embryonic development and is implicated in carcinogenesis. It is classified as a class frizzled (class F) G-protein-coupled receptor (GPCR), although the canonical hedgehog signalling pathway involves the GLI transcription factors and the sequence similarity with class A GPCRs is less than 10%. Here we report the crystal structure of the transmembrane domain of the human SMO receptor bound to the small-molecule antagonist LY2940680 at 2.5 Å resolution. Although the SMO receptor shares the seven-transmembrane helical fold, most of the conserved motifs for class A GPCRs are absent, and the structure reveals an unusually complex arrangement of long extracellular loops stabilized by four disulphide bonds. The ligand binds at the extracellular end of the seven-transmembrane-helix bundle and forms extensive contacts with the loops.
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Affiliation(s)
- Chong Wang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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172
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Kang HC, Wakabayashi Y, Jen KY, Mao JH, Zoumpourlis V, Rosario RD, Balmain A. Ptch1 overexpression drives skin carcinogenesis and developmental defects in K14Ptch(FVB) mice. J Invest Dermatol 2013; 133:1311-20. [PMID: 23223138 PMCID: PMC3610826 DOI: 10.1038/jid.2012.419] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ptch1 is a key regulator of embryonic development, acting through the sonic hedgehog (SHH) signaling pathway. Ptch1 is best known as a tumor suppressor, as germline or somatic mutations in Ptch1 lead to the formation of skin basal cell carcinomas. Here we show that Ptch1 also acts as a lineage-dependent oncogene, as overexpression of Ptch1 in adult skin in K14Ptch(FVB) transgenic mice synergizes with chemically induced Hras mutations to promote squamous carcinoma development. These effects were not because of aberrant activation of SHH signaling by the K14Ptch(FVB) transgene, as developmental defects in the highest expressing transgenic lines were consistent with the inhibition of this pathway. Carcinomas from K14Ptch(FVB) transgenic mice had only a small number of nonproliferative Ptch1 transgene-positive cells, suggesting that the Ptch1 transgene is not required for tumor maintenance, but may have a critical role in cell-fate determination at the initiation stage.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/adverse effects
- Animals
- Carcinoma, Squamous Cell/chemically induced
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/physiopathology
- Disease Models, Animal
- Fetal Development/genetics
- Fetal Development/physiology
- Gene Expression Regulation, Neoplastic/physiology
- Hedgehog Proteins/genetics
- Hedgehog Proteins/metabolism
- Keratin-14/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mutation
- Patched Receptors
- Patched-1 Receptor
- Proto-Oncogene Proteins p21(ras)/genetics
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Signal Transduction/genetics
- Signal Transduction/physiology
- Skin Neoplasms/chemically induced
- Skin Neoplasms/metabolism
- Skin Neoplasms/physiopathology
- Transgenes
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Affiliation(s)
- Hio Chung Kang
- Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Yuichi Wakabayashi
- Division of Experimental Animal Research, Chiba Cancer Center Research Institute, Nitonamachi Chuouku Chiba-city, Chiba-prefecture, Japan
| | - Kuang-Yu Jen
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Jian-Hua Mao
- Life Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA
| | - Vassilis Zoumpourlis
- National Hellenic Research Foundation, Institute of Biology, Medicinal Chemistry & Biotechnology, Athens, Greece
| | - Reyno Del Rosario
- Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Allan Balmain
- Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
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173
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Specialized filopodia direct long-range transport of SHH during vertebrate tissue patterning. Nature 2013; 497:628-32. [PMID: 23624372 PMCID: PMC4197975 DOI: 10.1038/nature12157] [Citation(s) in RCA: 277] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 04/08/2013] [Indexed: 12/20/2022]
Abstract
The ability of signaling proteins to traverse tissues containing tightly packed cells is of fundamental importance for cell specification and tissue development, however, how this is achieved at a cellular level remains poorly understood1. For over a century, the vertebrate limb bud has served as a paradigm to study cell signaling during embryonic development2. Here we optimize single cell real-time imaging to delineate the cellular mechanisms for how signaling proteins, such as Sonic Hedgehog (Shh), that possess membrane-bound covalent lipid modifications transverse long distances within the limb bud in vivo. By directly imaging Shh ligand production under native regulatory control, our findings show that Shh is unexpectedly produced in the form of a particle that remains associated with the cell via long cytoplasmic extensions that span several cell diameters. We show that these cellular extensions are a specialized class of actin-based filopodia with novel cytoskeletal features that have not been previously described. Strikingly, particles containing Shh traffic along these extensions with a net anterograde movement within the field of Shh cell signaling. We further show that in Shh responding cells specific subsets of Shh co-receptors, including Cdo and Boc, actively distribute and co-localize in specific micro-domains within filopodial extensions, far from the cell body. Stabilized interactions are formed between filopodia containing Shh ligand and those containing co-receptors over a long-range. These results suggest that contact-mediated release propagated by specialized filopodia contributes to the delivery of Shh at a distance. Together, these studies identify an important mode of communication between cells that significantly extends our understanding of ligand movement and reception during vertebrate tissue patterning.
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174
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Expression of SHH signaling molecules in the developing human primary dentition. BMC DEVELOPMENTAL BIOLOGY 2013; 13:11. [PMID: 23566240 PMCID: PMC3639830 DOI: 10.1186/1471-213x-13-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 04/04/2013] [Indexed: 11/10/2022]
Abstract
Background Our current knowledge on tooth development derives primarily from studies in mice. Very little is known about gene expression and function during human odontogenesis. Sonic Hedgehog (SHH) signaling has been demonstrated to play crucial roles in the development of multiple organs in mice, including the tooth. However, if SHH signaling molecules are expressed and function in the developing human embryonic tooth remain unknown. Results We conducted microarray assay to reveal the expression profile of SHH signaling pathway molecules. We then used in situ hybridization to validate and reveal spatial and temporal expression patterns of a number of selected molecules, including SHH, PTC1, SMO, GLI1, GLI2, and GLI3, in the developing human embryonic tooth germs, and compared them with that in mice. We found that all these genes exhibit similar but slightly distinct expression patterns in the human and mouse tooth germ at the cap and bell stages. Conclusions Our results demonstrate the operation of active SHH signaling in the developing human tooth and suggest a conserved function of SHH signaling pathway during human odontogenesis.
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175
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Gross JB, Kerney R, Hanken J, Tabin CJ. Molecular anatomy of the developing limb in the coquí frog, Eleutherodactylus coqui. Evol Dev 2013; 13:415-26. [PMID: 23016903 DOI: 10.1111/j.1525-142x.2011.00500.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The vertebrate limb demonstrates remarkable similarity in basic organization across phylogenetically disparate groups. To gain further insight into how this morphological similarity is maintained in different developmental contexts, we explored the molecular anatomy of size-reduced embryos of the Puerto Rican coquí frog, Eleutherodactylus coqui. This animal demonstrates direct development, a life-history strategy marked by rapid progression from egg to adult and absence of a free-living, aquatic larva. Nonetheless, coquí exhibits a basal anuran limb structure, with four toes on the forelimb and five toes on the hind limb. We investigated the extent to which coquí limb bud development conforms to the model of limb development derived from amniote studies. Toward this end, we characterized dynamic patterns of expression for 13 critical patterning genes across three principle stages of limb development. As expected, most genes demonstrate expression patterns that are essentially unchanged compared to amniote species. For example, we identified an EcFgf8-expression domain within the apical ectodermal ridge (AER). This expression pattern defines a putatively functional AER signaling domain, despite the absence of a morphological ridge in coquí embryos. However, two genes, EcMeis2 and EcAlx4, demonstrate altered domains of expression, which imply a potential shift in gene function between coquí frogs and amniote model systems. Unexpectedly, several genes thought to be critical for limb patterning in other systems, including EcFgf4, EcWnt3a, EcWnt7a, and EcGremlin, demonstrated no evident expression pattern in the limb at the three stages we analyzed. The absence of EcFgf4 and EcWnt3a expression during limb patterning is perhaps not surprising, given that neither gene is critical for proper limb development in the mouse, based on knockout and expression analyses. In contrast, absence of EcWnt7a and EcGremlin is surprising, given that expression of these molecules appears to be absolutely essential in all other model systems so far examined. Although this analysis substantiates the existence of a core set of ancient limb-patterning molecules, which likely mediate identical functions across highly diverse vertebrate forms, it also reveals remarkable evolutionary flexibility in the genetic control of a conserved morphological pattern across evolutionary time.
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Affiliation(s)
- Joshua B Gross
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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176
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Disturbance of SHH signalling pathway during early embryogenesis in the cadmium-induced omphalocele chick model. Pediatr Surg Int 2013; 29:165-70. [PMID: 23124188 DOI: 10.1007/s00383-012-3193-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Administration of cadmium (Cd) after 60 h (H) incubation induces ventral body wall defect (VBWD) similar to the omphalocele phenotype in the chick embryo. In this model, the earliest histological changes have been observed in somites commencing at 4-h post-treatment (4H). The molecular mechanism by which Cd acts in this critical period of embryogenesis still remains unclear. Sonic hedgehog (SHH) signalling plays an important role in vertebrate development, including somitogenesis and thus ventral body wall formation. Patched (PTCH), a cell membrane receptor for SHH, is expressed in somites and Patched knockout mice display somite dysfunction. Another transmembrane receptor, Smoothened (SMO), is also expressed in somites and transduces the SHH signal regulated by PTCH. We designed this study to test the hypothesis that SHH signalling is downregulated during the critical period of early embryogenesis in the Cd-induced omphalocele chick model. METHODS After 60 h of incubation, chicks were exposed to either chick saline or 50 μL of 50 μM cadmium acetate and divided into two groups: control and Cd (n = 24 for each group). Chicks were harvested 1, 4, and 8 h post-treatment. Real-time RT-PCR was performed to evaluate the relative mRNA expression level of SHH, PTCH and SMO. Immunofluorescence confocal microscopy was then performed to evaluate protein expression/distribution of SHH, PTCH and SMO. RESULTS The relative mRNA expression levels of SHH, PTCH and SMO were significantly downregulated in the Cd group compared to controls at 4H post treatment, whereas, there were no significant differences at the other time points. Immunohistochemistry revealed that the intensity of SHH, PTCH and SMO was markedly diminished at 4 h in Cd-treated embryos compared to controls. CONCLUSION Disturbance of the SHH signalling pathway as evidenced by SHH, PTCH and SMO downregulation during the narrow window of early embryogenesis may result in somite maldevelopment, contributing to the omphalocele phenotype in the Cd chick model.
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177
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Gastric cancer (GC) patients with hedgehog pathway activation: PTCH1 and GLI2 as independent prognostic factors. Target Oncol 2013; 8:271-80. [PMID: 23371028 DOI: 10.1007/s11523-013-0253-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 01/02/2013] [Indexed: 12/21/2022]
Abstract
Activation of sonic hedgehog (HH) signaling pathway has been implicated in aggressiveness and progression of gastrointestinal tumors. We planned this study to identify a subgroup of gastric cancer (GC) patients with HH activation and to assess the effect of a HH inhibitor in HH activated GC in vitro. We surveyed HH pathway activation among 512 GC specimens for protein expression of various target genes involved in HH pathway: Indian hedgehog (IHH), patched-1 (PTCH1), smoothened (SMO), GLI2, and FOXA2. We analyzed the correlations between the expression of these factors and clinicopathological features and prognosis. In vitro, ten gastric cancer cell lines were screened for anti-tumoractivity of an HH inhibitor, GDC-0449. Among the 512 specimens, 105 (20.0 %), 83 (16.3 %), 130 (25.5 %), 61 (12.0 %), and 206 (40.8 %) were positive for IHH, PTCH1, GLI2, SMO, and FOXA2 expression, respectively. PTCH1 expression was more frequently observed in well- or moderately differentiated tubular adenocarcinoma, intestinal type and low stage GC. GLI2 was correlated with lymphovascular invasion and intestinal type GC. A high-stage and negative PTCH1 staining were identified as unfavorable independent risk factors for overall survival in multivariate analysis (P < 0.001, 0.045, respectively). For IHH, SMO, and FOXA2, there was no statistical difference in clinicopathologic variables and survival outcome. An HH inhibitor had particularly potent effects on GC cell lines with SMO mRNA overexpression. This is the largest report to analyze the hedgehog pathway in GC. PTCH1 overexpression was an independent prognostic factor for survival and SMO overexpression which was found in 12.0 % of GC patients might be the potential predictive marker of HH inhibitor.
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178
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Kupinski AP, Raabe I, Michel M, Ail D, Brusch L, Weidemann T, Bökel C. Phosphorylation of the Smo tail is controlled by membrane localization and is dispensable for clustering. J Cell Sci 2013; 126:4684-97. [DOI: 10.1242/jcs.128926] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Hedgehog (Hh) signalling cascade is highly conserved and involved in development and disease throughout evolution. Nevertheless, in comparison with other pathways our mechanistic understanding of Hh signal transduction is remarkably incomplete. In the absence of ligand, the Hh receptor Patched (Ptc) represses the key signal transducer Smoothened (Smo) through an unknown mechanism. Hh binding to Ptc alleviates this repression, causing Smo redistribution to the plasma membrane, phosphorylation and opening of the Smo cytoplasmic tail, and Smo oligomerization. However, the order and interdependence of these events is as yet poorly understood. We have mathematically modelled and simulated Smo activation for two alternative modes of pathway activation, with Ptc primarily affecting either Smo localization or phosphorylation. Visualizing Smo activation through a novel, fluorescence based reporter allowed us to test these competing models. Here we show that Smo localization to the plasma membrane is sufficient for phosphorylation of the cytoplasmic tail in the presence of Ptc. Using fluorescence cross-correlation spectroscopy (FCCS) we furthermore demonstrate that inactivation of Ptc by Hh induces Smo clustering irrespective of Smo phosphorylation. Our observations therefore support a model of Hh signal transduction whereby Smo subcellular localization and not phosphorylation is the primary target of Ptc function.
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179
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Ishizuya-Oka A, Hasebe T. Establishment of intestinal stem cell niche during amphibian metamorphosis. Curr Top Dev Biol 2013; 103:305-27. [PMID: 23347524 DOI: 10.1016/b978-0-12-385979-2.00011-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the amphibian intestine during metamorphosis, most of the larval epithelial cells undergo apoptosis, whereas a small number of them survive. These cells dedifferentiate into stem cells through interactions with the microenvironment referred to as "stem cell niche" and generate the adult epithelium analogous to the mammalian counterpart. Since all processes of the larval-to-adult intestinal remodeling can be experimentally induced by thyroid hormone (TH) both in vivo and in vitro, the amphibian intestine provides us a valuable opportunity to study how adult stem cells and their niche are formed during postembryonic development. To address this issue, a number of expression and functional analyses of TH response genes have been intensely performed in the Xenopus laevis over the past two decades, by using organ culture and transgenic techniques. We here review recent progress in this field, focusing on key signaling pathways involved in establishment of the stem cell niche and discuss their evolutionarily conserved roles in the vertebrate intestine.
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180
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Lee J, Cox BD, Daly CMS, Lee C, Nuckels RJ, Tittle RK, Uribe RA, Gross JM. An ENU mutagenesis screen in zebrafish for visual system mutants identifies a novel splice-acceptor site mutation in patched2 that results in Colobomas. Invest Ophthalmol Vis Sci 2012; 53:8214-21. [PMID: 23150614 DOI: 10.1167/iovs.12-11061] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To identify recessive mutations affecting development and/or maintenance of the zebrafish visual system. METHODS A three-generation ENU (N-Nitroso-N-ethylurea)-based forward genetic screen was performed. F3 embryos were screened visually from 1 to 5 days postfertilization (dpf) for ocular abnormalities, and 5 dpf embryos were fixed and processed for cryosectioning, after which eye sections were screened for defects in cellular organization within the retina, lens, and cornea. A combination of PCR and DNA sequencing, in situ hybridization, and pharmacological treatments were used to clone and characterize a coloboma mutant. RESULTS A total of 126 F2 families were screened, and, from these, 18 recessive mutations were identified that affected eye development. Phenotypes included lens malformations and cataracts, photoreceptor defects, oculocutaneous albinism, microphthalmia, and colobomas. Analysis of one such coloboma mutant, uta(1), identified a splice-acceptor mutation in the patched2 gene that resulted in an in-frame deletion of 19 amino acids that are predicted to contribute to the first extracellular loop of Patched2. ptch2(uta1) mutants possessed elevated Hedgehog (Hh) pathway activity, and blocking the Hh pathway with cyclopamine prevented colobomas in ptch2(uta1) mutant embryos. CONCLUSIONS We have identified 18 recessive mutations affecting development of the zebrafish visual system and we have characterized a novel splice-acceptor site mutation in patched2 that results in enhanced Hh pathway activity and colobomas.
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Affiliation(s)
- Jiwoon Lee
- Section of Molecular Cell and Developmental Biology, Institute of Cell and Molecular Biology, The University of Texas at Austin, Texas 78712, USA
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181
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Horn A, Palumbo K, Cordazzo C, Dees C, Akhmetshina A, Tomcik M, Zerr P, Avouac J, Gusinde J, Zwerina J, Roudaut H, Traiffort E, Ruat M, Distler O, Schett G, Distler JHW. Hedgehog signaling controls fibroblast activation and tissue fibrosis in systemic sclerosis. ACTA ACUST UNITED AC 2012; 64:2724-33. [PMID: 22354771 DOI: 10.1002/art.34444] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Hedgehog signaling not only plays crucial roles during human development but also has been implicated in the pathogenesis of several diseases in adults. The aim of the present study was to investigate the role of the hedgehog pathway in fibroblast activation in systemic sclerosis (SSc). METHODS Activation of the hedgehog pathway was analyzed by immunohistochemistry and real-time polymerase chain reaction (PCR). The effects of sonic hedgehog (SHH) on collagen synthesis were analyzed by reporter assays, real-time PCR, and Sircol assays. Myofibroblast differentiation was assessed by quantification of α-smooth muscle actin and stress fiber staining. The role of hedgehog signaling in vivo was analyzed by adenoviral overexpression of SHH and using mice lacking 1 allele of the gene for inhibitory receptor Patched homolog 1 (Ptch(+/-) mice). RESULTS SHH was overexpressed and resulted in activation of hedgehog signaling in patients with SSc, with accumulation of the transcription factors Gli-1 and Gli-2 and increased transcription of hedgehog target genes. Activation of hedgehog signaling induced an activated phenotype in cultured fibroblasts, with differentiation of resting fibroblasts into myofibroblasts and increased release of collagen. Adenoviral overexpression of SHH in the skin of mice was sufficient to induce skin fibrosis. Moreover, Ptch(+/-) mice with increased hedgehog signaling were more sensitive to bleomycin-induced dermal fibrosis. CONCLUSION We demonstrated that the hedgehog pathway is activated in patients with SSc. Hedgehog signaling potently stimulates the release of collagen and myofibroblast differentiation in vitro and is sufficient to induce fibrosis in vivo. These findings identify the hedgehog cascade as a profibrotic pathway in SSc.
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182
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Büller NVJA, Rosekrans SL, Westerlund J, van den Brink GR. Hedgehog signaling and maintenance of homeostasis in the intestinal epithelium. Physiology (Bethesda) 2012; 27:148-55. [PMID: 22689790 DOI: 10.1152/physiol.00003.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Homeostasis of the rapidly renewing intestinal epithelium depends on a balance between cell proliferation and loss. Indian hedgehog (Ihh) acts as a negative feedback signal in this dynamic equilibrium. We discuss recent evidence that Ihh may be one of the key epithelial signals that indicates epithelial integrity to the underlying mesenchyme.
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Affiliation(s)
- Nikè V J A Büller
- Department of Gastroenterology & Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
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183
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Abstract
Hedgehog (Hh) proteins regulate the development of a wide range of metazoan embryonic and adult structures, and disruption of Hh signaling pathways results in various human diseases. Here, we provide a comprehensive review of the signaling pathways regulated by Hh, consolidating data from a diverse array of organisms in a variety of scientific disciplines. Similar to the elucidation of many other signaling pathways, our knowledge of Hh signaling developed in a sequential manner centered on its earliest discoveries. Thus, our knowledge of Hh signaling has for the most part focused on elucidating the mechanism by which Hh regulates the Gli family of transcription factors, the so-called "canonical" Hh signaling pathway. However, in the past few years, numerous studies have shown that Hh proteins can also signal through Gli-independent mechanisms collectively referred to as "noncanonical" signaling pathways. Noncanonical Hh signaling is itself subdivided into two distinct signaling modules: (i) those not requiring Smoothened (Smo) and (ii) those downstream of Smo that do not require Gli transcription factors. Thus, Hh signaling is now proposed to occur through a variety of distinct context-dependent signaling modules that have the ability to crosstalk with one another to form an interacting, dynamic Hh signaling network.
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Affiliation(s)
- David J Robbins
- Molecular Oncology Program, Department of Surgery, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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184
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Abstract
Hedgehog (HH) proteins are an important class of secreted intercellular signals. The HH signal-transduction pathway is not fully understood, but a number of novel features have been elucidated recently. It is now clear that, during processing to generate an active signal, Drosophila HH proteins become covalently linked to cholesterol and are thereby largely tethered to the cell surface. HH signalling could therefore be affected by cholesterol metabolism. In addition, the pathway downstream of receptor binding involves a unique signalling complex containing the transcription factor CUBITUS INTERRUPTUS (CI), which becomes dissociated from microtubules in response to HH. This review discusses these new findings and their implications for HH signalling.
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Affiliation(s)
- C J Tabin
- Dept of Genetics, Harvard Medical School, Boston, MA 02115, USA
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185
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Tukachinsky H, Kuzmickas RP, Jao CY, Liu J, Salic A. Dispatched and scube mediate the efficient secretion of the cholesterol-modified hedgehog ligand. Cell Rep 2012; 2:308-20. [PMID: 22902404 DOI: 10.1016/j.celrep.2012.07.010] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/11/2012] [Accepted: 07/25/2012] [Indexed: 01/31/2023] Open
Abstract
The Hedgehog (Hh) signaling pathway plays critical roles in metazoan development and in cancer. How the Hh ligand is secreted and spreads to distant cells is unclear, given its covalent modification with a hydrophobic cholesterol molecule, which makes it stick to membranes. We demonstrate that Hh ligand secretion from vertebrate cells is accomplished via two distinct and synergistic cholesterol-dependent binding events, mediated by two proteins that are essential for vertebrate Hh signaling: the membrane protein Dispatched (Disp) and a member of the Scube family of secreted proteins. Cholesterol modification is sufficient for a heterologous protein to interact with Scube and to be secreted in a Scube-dependent manner. Disp and Scube recognize different structural aspects of cholesterol similarly to how Niemann-Pick disease proteins 1 and 2 interact with cholesterol, suggesting a hand-off mechanism for transferring Hh from Disp to Scube. Thus, Disp and Scube cooperate to dramatically enhance the secretion and solubility of the cholesterol-modified Hh ligand.
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Affiliation(s)
- Hanna Tukachinsky
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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186
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Chang H, Balenci L, Okolowsky N, Muller WJ, Hamel PA. Mammary epithelial-restricted expression of activated c-src rescues the block to mammary gland morphogenesis due to the deletion of the C-terminus of Patched-1. Dev Biol 2012; 370:187-97. [PMID: 22968113 DOI: 10.1016/j.ydbio.2012.07.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 07/25/2012] [Accepted: 07/26/2012] [Indexed: 12/26/2022]
Abstract
Mesenchymal dysplasia (mes) mice expressing a C-terminally truncated version of the Hedgehog (Hh)-ligand receptor, Patched-1 (Ptch1), exhibit a limited spectrum of developmental defects including blocked ductal morphogenesis of the mammary gland during puberty. Given that the Hh-ligands can stimulate signalling cascades distinct from the canonical pathway involving Smo and the Gli-family proteins and that Ptch1 binds to factors harbouring SH3-domains, we determined whether the mes mammary gland defect could be rescued by activating non-canonical signalling pathways downstream of Ptch1. We demonstrate here that expression of constitutively active c-src (c-src(Act)) in mammary epithelial cells overcomes the block to mammary epithelial morphogenesis in mes mice. Specifically, MMTV-directed expression of c-src(Act) rescued blocked ductal morphogenesis in mes mice, albeit only after animals were more than 15 weeks of age. The overall morphology resembled wild type mice expressing c-src(Act) although 40% of mes/MMTV-c-src(Act) mice exhibited terminal end buds at 24 weeks of age. C-src(Act) restored the proliferative capacity of mes epithelial cells, self-renewal capacity of mammary progenitor cells and increased the expression of Esr1, Ptch1 and Gli1. These data reveal the cooperative interactions between signalling cascades involving c-src and Ptch1 and suggest that Hh-signalling may be permissive for c-src/Esr1-dependent mammary gland morphogenesis.
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Affiliation(s)
- Hong Chang
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Canada
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187
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Chong HJ, Young NM, Hu D, Jeong J, McMahon AP, Hallgrimsson B, Marcucio RS. Signaling by SHH rescues facial defects following blockade in the brain. Dev Dyn 2012; 241:247-56. [PMID: 22275045 DOI: 10.1002/dvdy.23726] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The Frontonasal Ectodermal Zone (FEZ) is a signaling center in the face that expresses Sonic hedgehog (Shh) and regulates patterned growth of the upper jaw. Blocking SHH in the forebrain blocks Shh expression in the FEZ and creates malformations resembling holoprosencephaly (HPE), while inhibition of BMP signaling in the mesenchyme blocks FEZ formation and causes similar dysmorphology. Thus, the brain could regulate FEZ formation by SHH or BMP signaling, and if so, activating one of these pathways in the face might alleviate the effects of repression of SHH in the brain. RESULTS We blocked SHH signaling in the brain while adding SHH or BMP between the neural and facial ectoderm of the frontonasal process. When applied early, SHH restored Shh expression in the FEZ and significantly improved shape outcomes, which contrasts with our previous experiments that showed later SHH treatments have no effect. BMP-soaked beads introduced early and late caused apoptosis that exacerbated malformations. Finally, removal of Smoothened from neural crest cells did not inhibit Shh expression in the FEZ. CONCLUSIONS Collectively, this work suggests that a direct, time-sensitive SHH signal from the brain is required for the later induction of Shh in the FEZ. We propose a testable model of FEZ activation and discuss signaling mediators that may regulate these interactions.
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Affiliation(s)
- H Jonathan Chong
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA
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188
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Rodriguez-Blanco J, Schilling NS, Tokhunts R, Giambelli C, Long J, Liang Fei D, Singh S, Black KE, Wang Z, Galimberti F, Bejarano PA, Elliot S, Glassberg MK, Nguyen DM, Lockwood WW, Lam WL, Dmitrovsky E, Capobianco AJ, Robbins DJ. The hedgehog processing pathway is required for NSCLC growth and survival. Oncogene 2012; 32:2335-45. [PMID: 22733134 DOI: 10.1038/onc.2012.243] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Considerable interest has been generated from the results of recent clinical trials using smoothened (SMO) antagonists to inhibit the growth of hedgehog (HH) signaling-dependent tumors. This interest is tempered by the discovery of SMO mutations mediating resistance, underscoring the rationale for developing therapeutic strategies that interrupt HH signaling at levels distinct from those inhibiting SMO function. Here, we demonstrate that HH-dependent non-small cell lung carcinoma (NSCLC) growth is sensitive to blockade of the HH pathway upstream of SMO, at the level of HH ligand processing. Individually, the use of different lentivirally delivered shRNA constructs targeting two functionally distinct HH-processing proteins, skinny hedgehog (SKN) or dispatched-1 (DISP-1), in NSCLC cell lines produced similar decreases in cell proliferation and increased cell death. Further, providing either an exogenous source of processed HH or a SMO agonist reverses these effects. The attenuation of HH processing, by knocking down either of these gene products, also abrogated tumor growth in mouse xenografts. Finally, we extended these findings to primary clinical specimens, showing that SKN is frequently overexpressed in NSCLC and that higher DISP-1 expression is associated with an unfavorable clinical outcome. Our results show a critical role for HH processing in HH-dependent tumors, identifies two potential druggable targets in the HH pathway, and suggest that similar therapeutic strategies could be explored to treat patients harboring HH ligand-dependent cancers.
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Affiliation(s)
- J Rodriguez-Blanco
- Molecular Oncology Program, Department of Surgery, University of Miami, Miami, FL 33136, USA
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189
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Epstein DJ. Regulation of thalamic development by sonic hedgehog. Front Neurosci 2012; 6:57. [PMID: 22529771 PMCID: PMC3328779 DOI: 10.3389/fnins.2012.00057] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/30/2012] [Indexed: 12/28/2022] Open
Abstract
The thalamus is strategically positioned within the caudal diencephalic area of the forebrain, between the mesencephalon and telencephalon. This location is important for unique aspects of thalamic function, to process and relay sensory and motor information to and from the cerebral cortex. How the thalamus comes to reside within this region of the central nervous system has been the subject of much investigation. Extracellular signals secreted from key locations both extrinsic and intrinsic to the thalamic primordium have recently been identified and shown to play important roles in the growth, regionalization, and specification of thalamic progenitors. One factor in particular, the secreted morphogen Sonic hedgehog (Shh), has been implicated in spatiotemporal and threshold models of thalamic development that differ from other areas of the CNS due, in large part, to its expression within two signaling centers, the basal plate and the zona limitans intrathalamica, a dorsally projecting spike that separates the thalamus from the subthalamic region. Shh signaling from these dual sources exhibit unique and overlapping functions in the control of thalamic progenitor identity and nuclei specification. This review will highlight recent advances in our understanding of Shh function during thalamic development, revealing similarities, and differences that exist between species.
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Affiliation(s)
- Douglas J Epstein
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, USA
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190
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Carroll CE, Marada S, Stewart DP, Ouyang JX, Ogden SK. The extracellular loops of Smoothened play a regulatory role in control of Hedgehog pathway activation. Development 2012; 139:612-21. [PMID: 22223683 DOI: 10.1242/dev.075614] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Hedgehog (Hh) signaling pathway plays an instructional role during development, and is frequently activated in cancer. Ligand-induced pathway activation requires signaling by the transmembrane protein Smoothened (Smo), a member of the G-protein-coupled receptor (GPCR) superfamily. The extracellular (EC) loops of canonical GPCRs harbor cysteine residues that engage in disulfide bonds, affecting active and inactive signaling states through regulating receptor conformation, dimerization and/or ligand binding. Although a functional importance for cysteines localized to the N-terminal extracellular cysteine-rich domain has been described, a functional role for a set of conserved cysteines in the EC loops of Smo has not yet been established. In this study, we mutated each of the conserved EC cysteines, and tested for effects on Hh signal transduction. Cysteine mutagenesis reveals that previously uncharacterized functional roles exist for Smo EC1 and EC2. We provide in vitro and in vivo evidence that EC1 cysteine mutation induces significant Hh-independent Smo signaling, triggering a level of pathway activation similar to that of a maximal Hh response in Drosophila and mammalian systems. Furthermore, we show that a single amino acid change in EC2 attenuates Hh-induced Smo signaling, whereas deletion of the central region of EC2 renders Smo fully active, suggesting that the conformation of EC2 is crucial for regulated Smo activity. Taken together, these findings are consistent with loop cysteines engaging in disulfide bonds that facilitate a Smo conformation that is silent in the absence of Hh, but can transition to a fully active state in response to ligand.
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Affiliation(s)
- Candace E Carroll
- Department of Biochemistry, St Jude Children's Research Hospital, 262 Danny Thomas Place, MS 340, Memphis, TN 38105, USA
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191
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Huang YS, Bu DF, Li XY, Ma ZH, Yang Y, Lin ZM, Lu FM, Tu P, Li H. Unique features of PTCH1 mutation spectrum in Chinese sporadic basal cell carcinoma. J Eur Acad Dermatol Venereol 2012; 27:235-41. [PMID: 22313357 DOI: 10.1111/j.1468-3083.2012.04453.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Alterations of the PTCH1 gene have been found to contribute to both familial and sporadic basal cell carcinoma (BCC), especially in Caucasian patients. Furthermore, the majority of PTCH1 gene mutations in sporadic BCCs in Caucasian patients carry ultraviolet (UV) signatures, suggesting the key role of UV light in BCC development. However, sporadic BCC in non-Caucasian population has a lower incidence, and the pathogenesis remains largely unknown. To date, there has been no mutation analysis on PTCH1 gene in Chinese patients with sporadic BCCs. OBJECTIVE To investigate genetic alterations of the PTCH1 gene in Chinese sporadic BCCs. METHODS Direct sequencing was used to screen for mutations in PTCH1 in 31 microdissected samples in Chinese sporadic BCCs. In addition, single nucleotide polymorphisms (SNPs) were studied for loss of heterozygosity (LOH). RESULTS Nineteen PTCH1 mutations in 17 of the 31 BCCs (54.8%) were identified. SNP analysis revealed LOH of PTCH1 in 10 of 23 BCCs (43.5%). Interestingly, the majority of mutations identified (63.2%) were insertion/deletion, which was different from the results in Caucasian cases whose mutations are predominantly point mutations. Only two (10.5%) of the remaining seven mutations were UV-specific C → T transition or tandem CC → TT transitions. All mutations occurred evenly throughout the entire PTCH1 protein domain without a hot-spot detected. CONCLUSION Mutations and LOH in PTCH1 were also highly prevalent in Chinese sporadic BCCs. However, UV light plays a less role in causing these mutations, suggesting other potential mechanisms in the development of sporadic BCC in Chinese patients.
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Affiliation(s)
- Y S Huang
- Department of Dermatology and Venereology, Peking University First Hospital, Beijing, China
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192
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Oxysterols are allosteric activators of the oncoprotein Smoothened. Nat Chem Biol 2012; 8:211-20. [PMID: 22231273 PMCID: PMC3262054 DOI: 10.1038/nchembio.765] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 11/03/2011] [Indexed: 12/13/2022]
Abstract
Oxysterols are a class of endogenous signaling molecules that can activate the Hedgehog pathway, which has critical roles in development, regeneration and cancer. However, it has been unclear how oxysterols influence Hedgehog signaling, including whether their effects are mediated through a protein target or indirectly through effects on membrane properties. To answer this question, we synthesized the enantiomer and an epimer of the most potent oxysterol, 20(S)-hydroxycholesterol. Using these molecules, we show that the effects of oxysterols on Hedgehog signaling are exquisitely stereoselective, consistent with the hypothesis that they function through a specific protein target. We present several lines of evidence that this protein target is the seven-pass transmembrane protein Smoothened, a major drug target in oncology. Our work suggests that these enigmatic sterols, which have multiple effects on cell physiology, may act as ligands for signaling receptors and provides a generally applicable framework for probing sterol signaling mechanisms.
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193
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Katanaev VL, Kryuchkov MV. The eye of Drosophila as a model system for studying intracellular signaling in ontogenesis and pathogenesis. BIOCHEMISTRY (MOSCOW) 2012; 76:1556-81. [DOI: 10.1134/s0006297911130116] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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194
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Currier DG, Polk RC, Reeves RH. A Sonic hedgehog (Shh) response deficit in trisomic cells may be a common denominator for multiple features of Down syndrome. PROGRESS IN BRAIN RESEARCH 2012; 197:223-36. [PMID: 22541295 PMCID: PMC4405118 DOI: 10.1016/b978-0-444-54299-1.00011-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The hedgehog (HH) family of growth factors is involved in many aspects of growth and development, from the establishment of left-right axes at gastrulation to the patterning and formation of multiple structures in essentially every tissue, to the maintenance and regulation of stem cell populations in adults. Sonic hedgehog (Shh) in particular acts as a mitogen, regulating proliferation of target cells, a growth factor that triggers differentiation in target populations, and a morphogen causing cells to respond differently based on their positions along a spatial and temporal concentration gradient. Given its very broad range of effects in development, it is not surprising that many of the structures affected by a disruption in Shh signaling are also affected in Down syndrome (DS). However, recent studies have shown that trisomic cerebellar granule cell precursors have a deficit, compared to their euploid counterparts, in their response to the mitogenic effects of Shh. This deficit substantially contributes to the hypocellular cerebellum in mouse models that parallels the human DS phenotype and can be corrected in early development by a single exposure to a small-molecule agonist of the Shh pathway. Here, we consider how an attenuated Shh response might affect several aspects of development to produce multiple phenotypic outcomes observed in DS.
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Affiliation(s)
- Duane G. Currier
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Renita C. Polk
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Roger H. Reeves
- Department of Physiology and The McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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195
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Hasebe T, Kajita M, Fu L, Shi YB, Ishizuya-Oka A. Thyroid hormone-induced sonic hedgehog signal up-regulates its own pathway in a paracrine manner in the Xenopus laevis intestine during metamorphosis. Dev Dyn 2011; 241:403-14. [PMID: 22190352 DOI: 10.1002/dvdy.23723] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND During Xenopus laevis metamorphosis, Sonic hedgehog (Shh) is directly induced by thyroid hormone (TH) at the transcription level as one of the earliest events in intestinal remodeling. However, the regulation of other components of this signaling pathway remains to be analyzed. Here, we analyzed the spatiotemporal expression of Patched (Ptc)-1, Smoothened (Smo), Gli1, Gli2, and Gli3 during natural and TH-induced intestinal remodeling. RESULTS We show that all of the genes examined are transiently up-regulated in the mesenchymal tissues during intestinal metamorphosis. CONCLUSIONS Interestingly, in the presence of protein synthesis inhibitors, Gli2 but not the others was induced by TH, suggesting that Gli2 is a direct TH response gene, while the others are likely indirect ones. Furthermore, we demonstrate by the organ culture experiment that overexpression of Shh enhances the expression of Ptc-1, Smo, and Glis even in the absence of TH, indicating that Shh regulates its own pathway components during intestinal remodeling.
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Affiliation(s)
- Takashi Hasebe
- Department of Biology, Nippon Medical School, Nakahara-ku, Kawasaki, Kanagawa, Japan.
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196
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Abstract
The Hedgehog (Hh) pathway is a conserved signalling system essential for embryonic development and for the maintenance of self-renewal pathways in progenitor cells. Mutations that deregulate Hh signalling are directly implicated in basal cell carcinoma and medulloblastoma. The mechanisms of Hh pathway activation in cancers in which no pathway mutations have been identified are less clear, but of great translational significance. Small molecule inhibitors of the pathway, many of which are in early phase clinical trials, may shed further light on this question. Canonical Hh signalling promotes the expression of target genes through the Glioma-associated oncogene (GLI) transcription factors. There is now increasing evidence suggesting that 'non-canonical' Hh signalling mechanisms, some of which are independent of GLI-mediated transcription, may be important in cancer and development. The focus of this review is to summarise some of the known mechanisms of Hh signalling as well as its emerging role in cancer.
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Affiliation(s)
- Kieren D Marini
- Monash Institute of Medical Research, Centre for Cancer Research, Monash University, Victoria, Australia
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197
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198
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Kiyasova V, Gaspar P. Development of raphe serotonin neurons from specification to guidance. Eur J Neurosci 2011; 34:1553-62. [DOI: 10.1111/j.1460-9568.2011.07910.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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199
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Bibliowicz J, Gross JM. Ectopic proliferation contributes to retinal dysplasia in the juvenile zebrafish patched2 mutant eye. Invest Ophthalmol Vis Sci 2011; 52:8868-77. [PMID: 22003118 DOI: 10.1167/iovs.11-8033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Patched is a well-studied tumor suppressor and negative regulator of the Hedgehog (Hh) pathway. Earlier work in this laboratory has shown that embryonic zebrafish patched2 (ptc2) mutant retinas possess an expanded ciliary marginal zone (CMZ) and phenotypes similar to those in human patients with basal cell naevus syndrome (BCNS), a congenital disorder linked to mutations in the human PTCH gene. This study extends the analysis of retinal structure and homeostasis in ptc2-/- mutants to juvenile stages, to determine whether Patched 2 function is essential in the postembryonic eye. METHODS Histologic, immunohistochemical, and molecular analyses were used to characterize retinal defects in the 6-week-old juvenile ptc2-/- retina. RESULTS Juvenile ptc2-/- mutants exhibited peripheral retinal dysplasias that included the presence of ectopic neuronal clusters in the inner nuclear layer (INL) and regions of disrupted retinal lamination. Retinal dysplasias were locally associated with ectopic proliferation. BrdU/EdU labeling and immunohistochemistry assays demonstrated that a population of ectopically proliferating cells gave rise to the ectopic neuronal clusters in the INL of ptc2-/- mutants and that this contributed to retinal dysplasia in the mutant eye. CONCLUSIONS These results demonstrate a direct link between overproliferation and retinal dysplasia in the ptc2-/- juvenile retina and establish ectopic proliferation as the likely cellular underpinning of retinal dysplasia in juvenile ptc2-/- mutants.
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Affiliation(s)
- Jonathan Bibliowicz
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, Texas, USA
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Allen BL, Song JY, Izzi L, Althaus IW, Kang JS, Charron F, Krauss RS, McMahon AP. Overlapping roles and collective requirement for the coreceptors GAS1, CDO, and BOC in SHH pathway function. Dev Cell 2011; 20:775-87. [PMID: 21664576 DOI: 10.1016/j.devcel.2011.04.018] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/16/2011] [Accepted: 04/30/2011] [Indexed: 12/11/2022]
Abstract
Secreted Hedgehog (HH) ligands signal through the canonical receptor Patched (PTCH1). However, recent studies implicate three additional HH-binding, cell-surface proteins, GAS1, CDO, and BOC, as putative coreceptors for HH ligands. A central question is to what degree these coreceptors function similarly and what their collective requirement in HH signal transduction is. Here we provide evidence that GAS1, CDO, and BOC play overlapping and essential roles during HH-mediated ventral neural patterning of the mammalian neural tube. Specifically, we demonstrate two important roles for these molecules: an early role in cell fate specification of multiple neural progenitors and a later role in motor neuron progenitor maintenance. Most strikingly, genetic loss-of-function experiments indicate an obligatory requirement for GAS1, CDO, and BOC in HH pathway activity in multiple tissues.
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Affiliation(s)
- Benjamin L Allen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, 48109, USA.
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