51
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Li S, Li S, Wang B, Jiang J. Hedgehog reciprocally controls trafficking of Smo and Ptc through the Smurf family of E3 ubiquitin ligases. Sci Signal 2018; 11:11/516/eaan8660. [PMID: 29438012 DOI: 10.1126/scisignal.aan8660] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hedgehog (Hh) induces signaling by promoting the reciprocal trafficking of its receptor Patched (Ptc) and the signal transducer Smoothened (Smo), which is inhibited by Ptc, at the cell surface. We identified Smurf family E3 ubiquitin ligases as essential for Smo ubiquitylation and cell surface clearance and demonstrated that Smurf family members mediate the reciprocal trafficking of Ptc and Smo in Drosophila melanogaster G protein-coupled receptor kinase 2 (Gprk2)-mediated phosphorylation of Smurf promoted Smo ubiquitylation by increasing the recruitment of Smurf to Smo, whereas protein kinase A (PKA)-mediated phosphorylation of Smo caused Smurf to dissociate from Smo, thereby inhibiting Smo ubiquitylation. Smo and Ptc competed for the same pool of Smurf family E3 ubiquitin ligases, and Hh promoted Ptc ubiquitylation and degradation by disrupting the association of Smurf family E3 ubiquitin ligases with Smo and stimulating their binding to Ptc. Our study identifies the E3 ubiquitin ligases that target Smo and provides insight into how Hh regulates the reciprocal trafficking of its receptor and signal transducer.
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Affiliation(s)
- Shuang Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Shuangxi Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Bing Wang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jin Jiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA. .,Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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52
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Jiang H, Zhang X, Chen X, Aramsangtienchai P, Tong Z, Lin H. Protein Lipidation: Occurrence, Mechanisms, Biological Functions, and Enabling Technologies. Chem Rev 2018; 118:919-988. [PMID: 29292991 DOI: 10.1021/acs.chemrev.6b00750] [Citation(s) in RCA: 283] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein lipidation, including cysteine prenylation, N-terminal glycine myristoylation, cysteine palmitoylation, and serine and lysine fatty acylation, occurs in many proteins in eukaryotic cells and regulates numerous biological pathways, such as membrane trafficking, protein secretion, signal transduction, and apoptosis. We provide a comprehensive review of protein lipidation, including descriptions of proteins known to be modified and the functions of the modifications, the enzymes that control them, and the tools and technologies developed to study them. We also highlight key questions about protein lipidation that remain to be answered, the challenges associated with answering such questions, and possible solutions to overcome these challenges.
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Affiliation(s)
- Hong Jiang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiaoyu Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiao Chen
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Pornpun Aramsangtienchai
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Zhen Tong
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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53
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Lu J, Wang D, Shen J. Hedgehog signalling is required for cell survival in Drosophila wing pouch cells. Sci Rep 2017; 7:11317. [PMID: 28900135 PMCID: PMC5595820 DOI: 10.1038/s41598-017-10550-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/10/2017] [Indexed: 11/09/2022] Open
Abstract
An appropriate balance between cell survival and cell death is essential for correct pattern formation in the animal tissues and organs. Previous studies have shown that the short-range signalling molecule Hedgehog (Hh) is required for cell proliferation and pattern formation in the Drosophila central wing discs. Signal transduction by one of the Hh targets, the morphogen Decapentaplegic (Dpp), is required for not only cell proliferation, but also cell survival in the pouch cells. However, Hh function in cell survival and cell death has not been revealed. Here, we found that loss of Hh signal activity induces considerable Caspase-dependent cell death in the wing pouch cells, and this process was independent of both Dpp signalling and Jun-N-terminal kinase (JNK) signalling. Loss of Hh induced activation of the pro-apoptotic gene hid and inhibition of diap1. Therefore, we identified an important role of Hh signalling in cell survival during Drosophila wing development.
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Affiliation(s)
- Juan Lu
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China
| | - Dan Wang
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China
| | - Jie Shen
- Department of Entomology, MOA Key Laboratory for monitoring and green management of crop pests, China Agricultural University, 100193, Beijing, China.
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54
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Gamboa NT, Taussky P, Park MS, Couldwell WT, Mahan MA, Kalani MYS. Neurovascular patterning cues and implications for central and peripheral neurological disease. Surg Neurol Int 2017; 8:208. [PMID: 28966815 PMCID: PMC5609400 DOI: 10.4103/sni.sni_475_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 06/28/2017] [Indexed: 12/20/2022] Open
Abstract
The highly branched nervous and vascular systems run along parallel trajectories throughout the human body. This stereotyped pattern of branching shared by the nervous and vascular systems stems from a common reliance on specific cues critical to both neurogenesis and angiogenesis. Continually emerging evidence supports the notion of later-evolving vascular networks co-opting neural molecular mechanisms to ensure close proximity and adequate delivery of oxygen and nutrients to nervous tissue. As our understanding of these biologic pathways and their phenotypic manifestations continues to advance, identification of where pathways go awry will provide critical insight into central and peripheral nervous system pathology.
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Affiliation(s)
- Nicholas T Gamboa
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Philipp Taussky
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Min S Park
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - William T Couldwell
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Mark A Mahan
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - M Yashar S Kalani
- Department of Neurosurgery, Clinical Neurosciences Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
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55
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Moghaddam SA, Yousefi B, Sanooghi D, Faghihi F, Hayati Roodbari N, Bana N, Joghataei MT, Pooyan P, Arjmand B. Differentiation potential of human CD133 positive hematopoietic stem cells into motor neuron- like cells, in vitro. J Chem Neuroanat 2017; 86:35-40. [PMID: 28754612 DOI: 10.1016/j.jchemneu.2017.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/12/2017] [Accepted: 07/19/2017] [Indexed: 01/15/2023]
Abstract
Spinal cord injuries and motor neuron-related disorders impact on life of many patients around the world. Since pharmacotherapy and surgical approaches were not efficient to regenerate these types of defects; stem cell therapy as a good strategy to restore the lost cells has become the focus of interest among the scientists. Umbilical cord blood CD133+ hematopoietic stem cells (UCB- CD133+ HSCs) with self- renewal property and neural lineage differentiation capacity are ethically approved cell candidate for use in regenerative medicine. In this regard the aim of this study was to quantitatively evaluate the capability of these cells to differentiate into motor neuron-like cells (MNL), in vitro. CD133+ HSCs were isolated from human UCB using MACS system. After cell characterization using flow cytometry, the cells were treated with a combination of Retinoic acid, Sonic hedgehog, Brain derived neurotrophic factor, and B27 through a 2- step procedure for two weeks. The expression of MN-specific markers was examined using qRT- PCR, flow cytometry and immunocytochemistry. By the end of the two-week differentiation protocol, CD133+ cells acquired unipolar MNL morphology with thin and long neurites. The expression of Isl-1(62.15%), AChE (41.83%), SMI-32 (21.55%) and Nestin (17.46%) was detected using flow cytometry and immunocytochemistry. The analysis of the expression of PAX6, ISL-1, ACHE, CHAT and SMI-32 revealed that MNLs present these neural markers at levels comparable with undifferentiated cells. In Conclusion Human UCB- CD133+ HSCs are remarkably potent cell candidates to transdifferentiate into motor neuron-like cells, in vitro.
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Affiliation(s)
| | - Behnam Yousefi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Davood Sanooghi
- Department of Genetics, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran
| | - Faezeh Faghihi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
| | - Nasim Hayati Roodbari
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Nikoo Bana
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Mohammad Taghi Joghataei
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran; Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Paria Pooyan
- Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
| | - Babak Arjmand
- Department of Neurosurgery and Iranian Tissue Bank, Tehran University of Medical Sciences/Tehran University, Tehran, Iran
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Abstract
Communication between cells pervades the development and physiology of metazoans. In animals, this process is carried out by a relatively small number of signaling pathways, each consisting of a chain of biochemical events through which extracellular stimuli control the behavior of target cells. One such signaling system is the Hedgehog pathway, which is crucial in embryogenesis and is implicated in many birth defects and cancers. Although Hedgehog pathway components were identified by genetic analysis more than a decade ago, our understanding of the molecular mechanisms of signaling is far from complete. In this review, we focus on the biochemistry and cell biology of the Hedgehog pathway. We examine the unique biosynthesis of the Hedgehog ligand, its specialized release from cells into extracellular space, and the poorly understood mechanisms involved in ligand reception and pathway activation at the surface of target cells. We highlight several critical questions that remain open.
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Affiliation(s)
- Kostadin Petrov
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
| | - Bradley M Wierbowski
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
| | - Adrian Salic
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115; ,
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57
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Saade M, Gonzalez-Gobartt E, Escalona R, Usieto S, Martí E. Shh-mediated centrosomal recruitment of PKA promotes symmetric proliferative neuroepithelial cell division. Nat Cell Biol 2017; 19:493-503. [PMID: 28446817 DOI: 10.1038/ncb3512] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 03/16/2017] [Indexed: 12/18/2022]
Abstract
Tight control of the balance between self-expanding symmetric and self-renewing asymmetric neural progenitor divisions is crucial to regulate the number of cells in the developing central nervous system. We recently demonstrated that Sonic hedgehog (Shh) signalling is required for the expansion of motor neuron progenitors by maintaining symmetric divisions. Here we show that activation of Shh/Gli signalling in dividing neuroepithelial cells controls the symmetric recruitment of PKA to the centrosomes that nucleate the mitotic spindle, maintaining symmetric proliferative divisions. Notably, Shh signalling upregulates the expression of pericentrin, which is required to dock PKA to the centrosomes, which in turn exerts a positive feedback onto Shh signalling. Thus, by controlling centrosomal protein assembly, we propose that Shh signalling overcomes the intrinsic asymmetry at the centrosome during neuroepithelial cell division, thereby promoting self-expanding symmetric divisions and the expansion of the progenitor pool.
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Affiliation(s)
- Murielle Saade
- Instituto de Biología Molecular de Barcelona, CSIC, ParcCientífic de Barcelona, C/Baldiri i Reixac 20, Barcelona 08028, Spain
| | - Elena Gonzalez-Gobartt
- Instituto de Biología Molecular de Barcelona, CSIC, ParcCientífic de Barcelona, C/Baldiri i Reixac 20, Barcelona 08028, Spain
| | - Rene Escalona
- Instituto de Biología Molecular de Barcelona, CSIC, ParcCientífic de Barcelona, C/Baldiri i Reixac 20, Barcelona 08028, Spain
| | - Susana Usieto
- Instituto de Biología Molecular de Barcelona, CSIC, ParcCientífic de Barcelona, C/Baldiri i Reixac 20, Barcelona 08028, Spain
| | - Elisa Martí
- Instituto de Biología Molecular de Barcelona, CSIC, ParcCientífic de Barcelona, C/Baldiri i Reixac 20, Barcelona 08028, Spain
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58
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Brorin is required for neurogenesis, gliogenesis, and commissural axon guidance in the zebrafish forebrain. PLoS One 2017; 12:e0176036. [PMID: 28448525 PMCID: PMC5407822 DOI: 10.1371/journal.pone.0176036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 04/04/2017] [Indexed: 12/28/2022] Open
Abstract
Bmps regulate numerous neural functions with their regulators. We previously identified Brorin, a neural-specific secreted antagonist of Bmp signaling, in humans, mice, and zebrafish. Mouse Brorin has two cysteine-rich domains containing 10 cysteine residues in its core region, and these are located in similar positions to those in the cysteine-rich domains of Chordin family members, which are secreted Bmp antagonists. Zebrafish Brorin had two cysteine-rich domains with high similarity to those of mouse Brorin. We herein examined zebrafish brorin in order to elucidate its in vivo actions. Zebrafish brorin was predominantly expressed in developing neural tissues. The overexpression of brorin led to the inactivation of Bmp signaling. On the other hand, the knockdown of brorin resulted in the activation of Bmp signaling and brorin morphants exhibited defective development of the ventral domain in the forebrain. Furthermore, the knockdown of brorin inhibited the generation of γ–aminobutyric acid (GABA)ergic interneurons and oligodendrocytes and promoted the generation of astrocytes in the forebrain. In addition, brorin was required for axon guidance in the forebrain. The present results suggest that Brorin is a secreted Bmp antagonist predominantly expressed in developing neural tissues and that it plays multiple roles in the development of the zebrafish forebrain.
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59
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Yousefi B, Sanooghi D, Faghihi F, Joghataei MT, Latifi N. Evaluation of motor neuron differentiation potential of human umbilical cord blood- derived mesenchymal stem cells, in vitro. J Chem Neuroanat 2017; 81:18-26. [PMID: 28153469 DOI: 10.1016/j.jchemneu.2017.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 12/25/2016] [Accepted: 01/22/2017] [Indexed: 10/20/2022]
Abstract
Many people suffer from spinal cord injuries annually. These deficits usually threaten the quality of life of patients. As a postpartum medically waste product, human Umbilical Cord Blood (UCB) is a rich source of stem cells with self- renewal properties and neural differentiation capacity which made it useful in regenerative medicine. Since there is no report on potential of human umbilical cord blood-derived mesenchymal stem cells into motor neurons, we set out to evaluate the differentiation properties of these cells into motor neuron-like cells through administration of Retinoic Acid(RA), Sonic Hedgehog(Shh) and BDNF using a three- step in vitro procedure. The results were evaluated using Real-time PCR, Flowcytometry and Immunocytochemistry for two weeks. Our data showed that the cells changed into bipolar morphology and could express markers related to motor neuron; including Hb-9, Pax-6, Islet-1, NF-H, ChAT at the level of mRNA and protein. We could also quantitatively evaluate the expression of Islet-1, ChAT and NF-H at 7 and 14days post- induction using flowcytometry. It is concluded that human UCB-MSCs is potent to express motor neuron- related markers in the presence of RA, Shh and BDNF through a three- step protocol; thus it could be a suitable cell candidate for regeneration of motor neurons in spinal cord injuries.
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Affiliation(s)
- Behnam Yousefi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Davood Sanooghi
- Department of Genetics, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran
| | - Faezeh Faghihi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.
| | - Mohammad Taghi Joghataei
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran; Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Nourahmad Latifi
- Department of Surgery, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
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60
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Ramsbottom SA, Pownall ME, Roelink H, Conway SJ. Regulation of Hedgehog Signalling Inside and Outside the Cell. J Dev Biol 2016; 4:23. [PMID: 27547735 PMCID: PMC4990124 DOI: 10.3390/jdb4030023] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The hedgehog (Hh) signalling pathway is conserved throughout metazoans and plays an important regulatory role in both embryonic development and adult homeostasis. Many levels of regulation exist that control the release, reception, and interpretation of the hedgehog signal. The fatty nature of the Shh ligand means that it tends to associate tightly with the cell membrane, and yet it is known to act as a morphogen that diffuses to elicit pattern formation. Heparan sulfate proteoglycans (HSPGs) play a major role in the regulation of Hh distribution outside the cell. Inside the cell, the primary cilium provides an important hub for processing the Hh signal in vertebrates. This review will summarise the current understanding of how the Hh pathway is regulated from ligand production, release, and diffusion, through to signal reception and intracellular transduction.
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Affiliation(s)
- Simon A. Ramsbottom
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, NE1 3BZ Newcastle upon Tyne, UK
- Correspondence: ; Tel.: +44-(0)191-241-8612
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61
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McGuigan AP, Javaherian S. Tissue Patterning: Translating Design Principles from In Vivo to In Vitro. Annu Rev Biomed Eng 2016; 18:1-24. [DOI: 10.1146/annurev-bioeng-083115-032943] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Alison P. McGuigan
- Department of Chemical Engineering and Applied Chemistry and
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3E5, Canada;
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62
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Kutejova E, Sasai N, Shah A, Gouti M, Briscoe J. Neural Progenitors Adopt Specific Identities by Directly Repressing All Alternative Progenitor Transcriptional Programs. Dev Cell 2016; 36:639-53. [PMID: 26972603 PMCID: PMC4819439 DOI: 10.1016/j.devcel.2016.02.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/29/2015] [Accepted: 02/12/2016] [Indexed: 01/01/2023]
Abstract
In the vertebrate neural tube, a morphogen-induced transcriptional network produces multiple molecularly distinct progenitor domains, each generating different neuronal subtypes. Using an in vitro differentiation system, we defined gene expression signatures of distinct progenitor populations and identified direct gene-regulatory inputs corresponding to locations of specific transcription factor binding. Combined with targeted perturbations of the network, this revealed a mechanism in which a progenitor identity is installed by active repression of the entire transcriptional programs of other neural progenitor fates. In the ventral neural tube, sonic hedgehog (Shh) signaling, together with broadly expressed transcriptional activators, concurrently activates the gene expression programs of several domains. The specific outcome is selected by repressive input provided by Shh-induced transcription factors that act as the key nodes in the network, enabling progenitors to adopt a single definitive identity from several initially permitted options. Together, the data suggest design principles relevant to many developing tissues. Specific vertebrate neural progenitor populations generated in vitro Gene expression dynamics, transcription factor binding assessed in neural progenitors Progenitor fate selected by repressors blocking entire programs of other identities Repressors counteract non-selective morphogen and pan-neural activatory inputs
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Affiliation(s)
- Eva Kutejova
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Noriaki Sasai
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Ankita Shah
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Mina Gouti
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - James Briscoe
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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63
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Jeon S, Seong RH. Anteroposterior Limb Skeletal Patterning Requires the Bifunctional Action of SWI/SNF Chromatin Remodeling Complex in Hedgehog Pathway. PLoS Genet 2016; 12:e1005915. [PMID: 26959361 PMCID: PMC4784730 DOI: 10.1371/journal.pgen.1005915] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/15/2016] [Indexed: 11/24/2022] Open
Abstract
Graded Sonic hedgehog (Shh) signaling governs vertebrate limb skeletal patterning along the anteroposterior (AP) axis by regulating the activity of bifunctional Gli transcriptional regulators. The genetic networks involved in this patterning are well defined, however, the epigenetic control of the process by chromatin remodelers remains unknown. Here, we report that the SWI/SNF chromatin remodeling complex is essential for Shh-driven limb AP patterning. Specific inactivation of Srg3/mBaf155, a core subunit of the remodeling complex, in developing limb buds hampered the transcriptional upregulation of Shh/Gli target genes, including the Shh receptor Ptch1 and its downstream effector Gli1 in the posterior limb bud. In addition, Srg3 deficiency induced ectopic activation of the Hedgehog (Hh) pathway in the anterior mesenchyme, resulting in loss of progressive asymmetry. These defects in the Hh pathway accompanied aberrant BMP activity and disruption of chondrogenic differentiation in zeugopod and autopod primordia. Notably, our data revealed that dual control of the Hh pathway by the SWI/SNF complex is essential for spatiotemporal transcriptional regulation of the BMP antagonist Gremlin1, which affects the onset of chondrogenesis. This study uncovers the bifunctional role of the SWI/SNF complex in the Hh pathway to determine the fate of AP skeletal progenitors. Anteroposterior (AP) limb skeletal patterning is directed by morphogen Sonic hedgehog (Shh) signaling. Modulation of Shh responsiveness and repression of Shh pathway activity in distinct limb bud regions are essential for proper limb skeletal formation. Although the genetic networks involved in these processes have been identified, epigenetic control by chromatin remodeler remains unknown. We have unraveled the function of the SWI/SNF chromatin remodeling complex in Shh signaling during limb patterning. The complex activates the responses of the posterior limb progenitors to Shh, however, it represses the signaling in the anterior limb progenitors. Here we provide genetic evidence for the dual requirement of the SWI/SNF complex in Shh signaling to pattern AP limb skeletal elements.
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Affiliation(s)
- Shin Jeon
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Korea
| | - Rho Hyun Seong
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Korea
- * E-mail:
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64
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Tolosa EJ, Fernández-Zapico ME, Battiato NL, Rovasio RA. Sonic hedgehog is a chemotactic neural crest cell guide that is perturbed by ethanol exposure. Eur J Cell Biol 2016; 95:136-52. [DOI: 10.1016/j.ejcb.2016.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 01/23/2016] [Accepted: 02/17/2016] [Indexed: 12/12/2022] Open
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65
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Richards DM, Saunders TE. Spatiotemporal analysis of different mechanisms for interpreting morphogen gradients. Biophys J 2016; 108:2061-73. [PMID: 25902445 DOI: 10.1016/j.bpj.2015.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 03/05/2015] [Accepted: 03/10/2015] [Indexed: 10/23/2022] Open
Abstract
During development, multicellular organisms must accurately control both temporal and spatial aspects of tissue patterning. This is often achieved using morphogens, signaling molecules that form spatially varying concentrations and so encode positional information. Typical analysis of morphogens assumes that spatial information is decoded in steady state by measuring the value of the morphogen concentration. However, recent experimental work suggests that both pre-steady-state readout and measurement of spatial and temporal derivatives of the morphogen concentration can play important roles in defining boundaries. Here, we undertake a detailed theoretical and numerical study of the accuracy of patterning-both in space and time-in models where readout is provided not by the morphogen concentration but by its spatial and temporal derivatives. In both cases we find that accurate patterning can be achieved, with sometimes even smaller errors than directly reading the morphogen concentration. We further demonstrate that such models provide other potential benefits to the system, such as the ability to switch on and off gene response with a high degree of spatiotemporal accuracy. Finally, we discuss how such derivatives might be calculated biologically and examine these models in relation to Sonic Hedgehog signaling in the vertebrate central nervous system. We show that, when coupled to a downstream transcriptional network, pre-steady-state measurement of the temporal change in the Shh morphogen is a plausible mechanism for determining precise gene boundaries in both space and time.
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Affiliation(s)
- David M Richards
- Department of Life Sciences, Imperial College, London, United Kingdom.
| | - Timothy E Saunders
- Mechanobiology Institute, National University of Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore; Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Singapore.
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66
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MicroRNA Biogenesis and Hedgehog-Patched Signaling Cooperate to Regulate an Important Developmental Transition in Granule Cell Development. Genetics 2016; 202:1105-18. [PMID: 26773048 DOI: 10.1534/genetics.115.184176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/10/2016] [Indexed: 12/20/2022] Open
Abstract
The Dicer1, Dcr-1 homolog (Drosophila) gene encodes a type III ribonuclease required for the canonical maturation and functioning of microRNAs (miRNAs). Subsets of miRNAs are known to regulate normal cerebellar granule cell development, in addition to the growth and progression of medulloblastoma, a neoplasm that often originates from granule cell precursors. Multiple independent studies have also demonstrated that deregulation of Sonic Hedgehog (Shh)-Patched (Ptch) signaling, through miRNAs, is causative of granule cell pathologies. In the present study, we investigated the genetic interplay between miRNA biogenesis and Shh-Ptch signaling in granule cells of the cerebellum by way of the Cre/lox recombination system in genetically engineered models of Mus musculus (mouse). We demonstrate that, although the miRNA biogenesis and Shh-Ptch-signaling pathways, respectively, regulate the opposing growth processes of cerebellar hypoplasia and hyperplasia leading to medulloblastoma, their concurrent deregulation was nonadditive and did not bring the growth phenotypes toward an expected equilibrium. Instead, mice developed either hypoplasia or medulloblastoma, but of a greater severity. Furthermore, some genotypes were bistable, whereby subsets of mice developed hypoplasia or medulloblastoma. This implies that miRNAs and Shh-Ptch signaling regulate an important developmental transition in granule cells of the cerebellum. We also conclusively show that the Dicer1 gene encodes a haploinsufficient tumor suppressor gene for Ptch1-induced medulloblastoma, with the monoallielic loss of Dicer1 more severe than biallelic loss. These findings exemplify how genetic interplay between pathways may produce nonadditive effects with a substantial and unpredictable impact on biology. Furthermore, these findings suggest that the functional dosage of Dicer1 may nonadditively influence a wide range of Shh-Ptch-dependent pathologies.
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67
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The many lives of SHH in limb development and evolution. Semin Cell Dev Biol 2016; 49:116-24. [DOI: 10.1016/j.semcdb.2015.12.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 12/21/2015] [Accepted: 12/23/2015] [Indexed: 01/17/2023]
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68
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Morales AV, Espeso-Gil S, Ocaña I, Nieto-Lopez F, Calleja E, Bovolenta P, Lewandoski M, Diez Del Corral R. FGF signaling enhances a sonic hedgehog negative feedback loop at the initiation of spinal cord ventral patterning. Dev Neurobiol 2015; 76:956-71. [PMID: 26600420 DOI: 10.1002/dneu.22368] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 11/18/2015] [Indexed: 12/23/2022]
Abstract
A prevalent developmental mechanism for the assignment of cell identities is the production of spatiotemporal concentration gradients of extracellular signaling molecules that are interpreted by the responding cells. One of such signaling systems is the Shh gradient that controls neuronal subtype identity in the ventral spinal cord. Using loss and gain of function approaches in chick and mouse embryos, we show here that the fibroblast growth factor (FGF) signaling pathway is required to restrict the domains of ventral gene expression as neuroepithelial cells become exposed to Shh during caudal extension of the embryo. FGF signaling activates the expression of the Shh receptor and negative pathway regulator Patched 2 (Ptch2) and therefore can enhance a negative feedback loop that restrains the activity of the pathway. Thus, we identify one of the mechanisms by which FGF signaling acts as a modulator of the onset of Shh signaling activity in the context of coordination of ventral patterning and caudal axis extension. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 956-971, 2016.
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Affiliation(s)
- Aixa V Morales
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain
| | - Sergio Espeso-Gil
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain
| | - Inmaculada Ocaña
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain.,CIBER de Enfermedades Raras, Spain
| | - Francisco Nieto-Lopez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain.,CIBER de Enfermedades Raras, Spain.,Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-UAM, Cantoblanco, 28049, Spain
| | - Elena Calleja
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain
| | - Paola Bovolenta
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain.,CIBER de Enfermedades Raras, Spain.,Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas-UAM, Cantoblanco, 28049, Spain
| | - Mark Lewandoski
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, 21702, USA
| | - Ruth Diez Del Corral
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, 28002, Spain
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69
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Abstract
The Drosophila blastoderm and the vertebrate neural tube are archetypal examples of morphogen-patterned tissues that create precise spatial patterns of different cell types. In both tissues, pattern formation is dependent on molecular gradients that emanate from opposite poles. Despite distinct evolutionary origins and differences in time scales, cell biology and molecular players, both tissues exhibit striking similarities in the regulatory systems that establish gene expression patterns that foreshadow the arrangement of cell types. First, signaling gradients establish initial conditions that polarize the tissue, but there is no strict correspondence between specific morphogen thresholds and boundary positions. Second, gradients initiate transcriptional networks that integrate broadly distributed activators and localized repressors to generate patterns of gene expression. Third, the correct positioning of boundaries depends on the temporal and spatial dynamics of the transcriptional networks. These similarities reveal design principles that are likely to be broadly applicable to morphogen-patterned tissues.
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Affiliation(s)
- James Briscoe
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Stephen Small
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
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70
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Wiese S, Faissner A. The role of extracellular matrix in spinal cord development. Exp Neurol 2015; 274:90-9. [DOI: 10.1016/j.expneurol.2015.05.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 05/13/2015] [Accepted: 05/25/2015] [Indexed: 01/06/2023]
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71
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Cochrane CR, Szczepny A, Watkins DN, Cain JE. Hedgehog Signaling in the Maintenance of Cancer Stem Cells. Cancers (Basel) 2015; 7:1554-85. [PMID: 26270676 PMCID: PMC4586784 DOI: 10.3390/cancers7030851] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 07/31/2015] [Accepted: 08/03/2015] [Indexed: 12/13/2022] Open
Abstract
Cancer stem cells (CSCs) represent a rare population of cells with the capacity to self-renew and give rise to heterogeneous cell lineages within a tumour. Whilst the mechanisms underlying the regulation of CSCs are poorly defined, key developmental signaling pathways required for normal stem and progenitor functions have been strongly implicated. Hedgehog (Hh) signaling is an evolutionarily-conserved pathway essential for self-renewal and cell fate determination. Aberrant Hh signaling is associated with the development and progression of various types of cancer and is implicated in multiple aspects of tumourigenesis, including the maintenance of CSCs. Here, we discuss the mounting evidence suggestive of Hh-driven CSCs in the context of haematological malignancies and solid tumours and the novel strategies that hold the potential to block many aspects of the transformation attributed to the CSC phenotype, including chemotherapeutic resistance, relapse and metastasis.
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Affiliation(s)
- Catherine R Cochrane
- Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia.
- Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia.
| | - Anette Szczepny
- Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia.
- Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia.
| | - D Neil Watkins
- The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia.
- UNSW Faculty of Medicine, Randwick, New South Wales 2031, Australia.
- Department of Thoracic Medicine, St Vincent's Hospital, Darlinghurst, New South Wales 2010, Australia.
| | - Jason E Cain
- Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia.
- Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia.
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Rosin JM, Kurrasch DM, Cobb J. Shox2 is required for the proper development of the facial motor nucleus and the establishment of the facial nerves. BMC Neurosci 2015; 16:39. [PMID: 26156498 PMCID: PMC4495855 DOI: 10.1186/s12868-015-0176-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/12/2015] [Indexed: 11/10/2022] Open
Abstract
Background Axons from the visceral motor neurons (vMNs) project from nuclei in the hindbrain to innervate autonomic ganglia and branchial arch-derived muscles. Although much is known about the events that govern specification of somatic motor neurons, the genetic pathways responsible for the development of vMNs are less well characterized. We know that vMNs, like all motor neurons, depend on sonic hedgehog signaling for their generation. Similarly, the paired-like homeobox 2b (Phox2b) gene, which is expressed in both proliferating progenitors and post-mitotic motor neurons, is essential for the development of vMNs. Given that our previous study identified a novel role for the short stature homeobox 2 (Shox2) gene in the hindbrain, and since SHOX2 has been shown to regulate transcription of islet 1 (Isl1), an important regulator of vMN development, we sought to determine whether Shox2 is required for the proper development of the facial motor nucleus. Results Using a Nestin-Cre driver, we show that elimination of Shox2 throughout the brain results in elevated cell death in the facial motor nucleus at embryonic day 12.5 (E12.5) and E14.5, which correlates with impaired axonal projection properties of vMNs. We also observed changes in the spatial expression of the vMN cell fate factors Isl1 and Phox2b, and concomitant defects in Shh and Ptch1 expression in Shox2 mutants. Furthermore, we demonstrate that elimination of Shox2 results in the loss of dorsomedial and ventromedial subnuclei by postnatal day 0 (P0), which may explain the changes in physical activity and impaired feeding/nursing behavior in Shox2 mutants. Conclusions Combined, our data show that Shox2 is required for development of the facial motor nucleus and its associated facial (VII) nerves, and serves as a new molecular tool to probe the genetic programs of this understudied hindbrain region. Electronic supplementary material The online version of this article (doi:10.1186/s12868-015-0176-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jessica M Rosin
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., BI286D, Calgary, AB, T2N 1N4, Canada.
| | - Deborah M Kurrasch
- Department of Medical Genetics, Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive N.W., Room HS2275, Calgary, AB, T2N 4N1, Canada.
| | - John Cobb
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., BI286D, Calgary, AB, T2N 1N4, Canada.
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Holtz AM, Griffiths SC, Davis SJ, Bishop B, Siebold C, Allen BL. Secreted HHIP1 interacts with heparan sulfate and regulates Hedgehog ligand localization and function. J Cell Biol 2015; 209:739-57. [PMID: 26056142 PMCID: PMC4460154 DOI: 10.1083/jcb.201411024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 04/24/2015] [Indexed: 01/21/2023] Open
Abstract
Vertebrate Hedgehog (HH) signaling is controlled by several ligand-binding antagonists including Patched-1 (PTCH1), PTCH2, and HH-interacting protein 1 (HHIP1), whose collective action is essential for proper HH pathway activity. However, the molecular mechanisms used by these inhibitors remain poorly understood. In this paper, we investigated the mechanisms underlying HHIP1 antagonism of HH signaling. Strikingly, we found evidence that HHIP1 non-cell-autonomously inhibits HH-dependent neural progenitor patterning and proliferation. Furthermore, this non-cell-autonomous antagonism of HH signaling results from the secretion of HHIP1 that is modulated by cell type-specific interactions with heparan sulfate (HS). These interactions are mediated by an HS-binding motif in the cysteine-rich domain of HHIP1 that is required for its localization to the neuroepithelial basement membrane (BM) to effectively antagonize HH pathway function. Our data also suggest that endogenous, secreted HHIP1 localization to HS-containing BMs regulates HH ligand distribution. Overall, the secreted activity of HHIP1 represents a novel mechanism to regulate HH ligand localization and function during embryogenesis.
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Affiliation(s)
- Alexander M Holtz
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109 Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109 Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109
| | - Samuel C Griffiths
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England, UK
| | - Samantha J Davis
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Benjamin Bishop
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England, UK
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England, UK
| | - Benjamin L Allen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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Kim J, Hsia EYC, Brigui A, Plessis A, Beachy PA, Zheng X. The role of ciliary trafficking in Hedgehog receptor signaling. Sci Signal 2015; 8:ra55. [PMID: 26038600 DOI: 10.1126/scisignal.aaa5622] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Defects in the biogenesis of or transport through primary cilia affect Hedgehog protein signaling, and many Hedgehog pathway components traffic through or accumulate in cilia. The Hedgehog receptor Patched negatively regulates the activity and ciliary accumulation of Smoothened, a seven-transmembrane protein that is essential for transducing the Hedgehog signal. We found that this negative regulation of Smoothened required the ciliary localization of Patched, as specified either by its own cytoplasmic tail or by provision of heterologous ciliary localization signals. Surprisingly, given that Hedgehog binding promotes the exit of Patched from the cilium, we observed that an altered form of Patched that is retained in the cilium nevertheless responded to Hedgehog, resulting in Smoothened activation. Our results indicate that whereas ciliary localization of Patched is essential for suppression of Smoothened activation, the primary event enabling Smoothened activation is binding of Hedgehog to Patched, and Patched ciliary removal is secondary.
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Affiliation(s)
- Jynho Kim
- Departments of Biochemistry and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA. Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elaine Y C Hsia
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Amira Brigui
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | - Anne Plessis
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | - Philip A Beachy
- Departments of Biochemistry and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA. Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Xiaoyan Zheng
- Departments of Biochemistry and Developmental Biology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA. Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA.
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75
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Hsia EYC, Gui Y, Zheng X. Regulation of Hedgehog signaling by ubiquitination. FRONTIERS IN BIOLOGY 2015; 10:203-220. [PMID: 26366162 PMCID: PMC4564008 DOI: 10.1007/s11515-015-1343-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Hedgehog (Hh) signaling pathway plays crucial roles both in embryonic development and in adult stem cell function. The timing, duration and location of Hh signaling activity need to be tightly controlled. Abnormalities of Hh signal transduction lead to birth defects or malignant tumors. Recent data point to ubiquitination-related posttranslational modifications of several key Hh pathway components as an important mechanism of regulation of the Hh pathway. Here we review how ubiquitination regulates the localization, stability and activity of the key Hh signaling components.
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Affiliation(s)
- Elaine Y. C. Hsia
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Yirui Gui
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
| | - Xiaoyan Zheng
- Department of Anatomy and Regenerative Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037, USA
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76
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Cohen M, Kicheva A, Ribeiro A, Blassberg R, Page KM, Barnes CP, Briscoe J. Ptch1 and Gli regulate Shh signalling dynamics via multiple mechanisms. Nat Commun 2015; 6:6709. [PMID: 25833741 PMCID: PMC4396374 DOI: 10.1038/ncomms7709] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 02/20/2015] [Indexed: 12/20/2022] Open
Abstract
In the vertebrate neural tube, the morphogen Sonic Hedgehog (Shh) establishes a characteristic pattern of gene expression. Here we quantify the Shh gradient in the developing mouse neural tube and show that while the amplitude of the gradient increases over time, the activity of the pathway transcriptional effectors, Gli proteins, initially increases but later decreases. Computational analysis of the pathway suggests three mechanisms that could contribute to this adaptation: transcriptional upregulation of the inhibitory receptor Ptch1, transcriptional downregulation of Gli and the differential stability of active and inactive Gli isoforms. Consistent with this, Gli2 protein expression is downregulated during neural tube patterning and adaptation continues when the pathway is stimulated downstream of Ptch1. Moreover, the Shh-induced upregulation of Gli2 transcription prevents Gli activity levels from adapting in a different cell type, NIH3T3 fibroblasts, despite the upregulation of Ptch1. Multiple mechanisms therefore contribute to the intracellular dynamics of Shh signalling, resulting in different signalling dynamics in different cell types.
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Affiliation(s)
- Michael Cohen
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Anna Kicheva
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Ana Ribeiro
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Robert Blassberg
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Karen M Page
- Department of Mathematics and CoMPLEX, University College London, Gower Street, London WC1E 6BT, UK
| | - Chris P Barnes
- 1] Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK [2] Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - James Briscoe
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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Haddad-Tóvolli R, Paul FA, Zhang Y, Zhou X, Theil T, Puelles L, Blaess S, Alvarez-Bolado G. Differential requirements for Gli2 and Gli3 in the regional specification of the mouse hypothalamus. Front Neuroanat 2015; 9:34. [PMID: 25859185 PMCID: PMC4373379 DOI: 10.3389/fnana.2015.00034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/09/2015] [Indexed: 11/13/2022] Open
Abstract
Secreted protein Sonic hedgehog (Shh) ventralizes the neural tube by modulating the crucial balance between activating and repressing functions (GliA, GliR) of transcription factors Gli2 and Gli3. This balance—the Shh-Gli code—is species- and context-dependent and has been elucidated for the mouse spinal cord. The hypothalamus, a forebrain region regulating vital functions like homeostasis and hormone secretion, shows dynamic and intricate Shh expression as well as complex regional differentiation. Here we asked if particular combinations of Gli2 and Gli3 and of GliA and GliR functions contribute to the variety of hypothalamic regions, i.e., we wanted to approach the question of a possible hypothalamic version of the Shh-Gli code. Based on mouse mutant analysis, we show that: (1) hypothalamic regional heterogeneity is based in part on differentially stringent requirements for Gli2 or Gli3; (2) another source of diversity are differential requirements for Shh of neural vs. non-neural origin; (3) the medial progenitor domain known to depend on Gli2 for its development generates several essential hypothalamic nuclei plus the pituitary and median eminence; (4) the suppression of Gli3R by neural and non-neural Shh is essential for hypothalamic specification. Finally, we have mapped our results on a recent model which considers the hypothalamus as a transverse region with alar and basal portions. Our data confirm the model and are explained by it.
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Affiliation(s)
- Roberta Haddad-Tóvolli
- Department of Medical Cell Biology and Neuroanatomy, University of Heidelberg Heidelberg, Germany
| | - Fabian A Paul
- Laboratory of Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn Bonn, Germany
| | - Yuanfeng Zhang
- Department of Medical Cell Biology and Neuroanatomy, University of Heidelberg Heidelberg, Germany
| | - Xunlei Zhou
- Department of Medical Cell Biology and Neuroanatomy, University of Heidelberg Heidelberg, Germany
| | - Thomas Theil
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
| | - Luis Puelles
- Department of Morphology, Instituto Murciano de Investigación Biosanitaria, School of Medicine, University of Murcia Murcia, Spain ; Facultad de Medicina, University of Murcia Murcia, Spain
| | - Sandra Blaess
- Laboratory of Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn Bonn, Germany
| | - Gonzalo Alvarez-Bolado
- Department of Medical Cell Biology and Neuroanatomy, University of Heidelberg Heidelberg, Germany
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78
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Differentiation Potential of Human Chorion-Derived Mesenchymal Stem Cells into Motor Neuron-Like Cells in Two- and Three-Dimensional Culture Systems. Mol Neurobiol 2015; 53:1862-1872. [PMID: 25790953 DOI: 10.1007/s12035-015-9129-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/22/2015] [Indexed: 12/29/2022]
Abstract
Many people worldwide suffer from motor neuron-related disorders such as amyotrophic lateral sclerosis and spinal cord injuries. Recently, several attempts have been made to recruit stem cells to modulate disease progression in ALS and also regenerate spinal cord injuries. Chorion-derived mesenchymal stem cells (C-MSCs), used to be discarded as postpartum medically waste product, currently represent a class of cells with self renewal property and immunomodulatory capacity. These cells are able to differentiate into mesodermal and nonmesodermal lineages such as neural cells. On the other hand, gelatin, as a simply denatured collagen, is a suitable substrate for cell adhesion and differentiation. It has been shown that electrospinning of scaffolds into fibrous structure better resembles the physiological microenvironment in comparison with two-dimensional (2D) culture system. Since there is no report on potential of human chorion-derived MSCs to differentiate into motor neuron cells in two- and three-dimensional (3D) culture systems, we set out to determine the effect of retinoic acid (RA) and sonic hedgehog (Shh) on differentiation of human C-MSCs into motor neuron-like cells cultured on tissue culture plates (2D) and electrospun nanofibrous gelatin scaffold (3D).
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79
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Hu D, Young NM, Li X, Xu Y, Hallgrímsson B, Marcucio RS. A dynamic Shh expression pattern, regulated by SHH and BMP signaling, coordinates fusion of primordia in the amniote face. Development 2015; 142:567-74. [PMID: 25605783 DOI: 10.1242/dev.114835] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mechanisms of morphogenesis are not well understood, yet shaping structures during development is essential for establishing correct organismal form and function. Here, we examine mechanisms that help to shape the developing face during the crucial period of facial primordia fusion. This period of development is a time when the faces of amniote embryos exhibit the greatest degree of similarity, and it probably results from the necessity for fusion to occur to establish the primary palate. Our results show that hierarchical induction mechanisms, consisting of iterative signaling by Sonic hedgehog (SHH) followed by Bone morphogenetic proteins (BMPs), regulate a dynamic expression pattern of Shh in the ectoderm covering the frontonasal (FNP) and maxillary (MxP) processes. Furthermore, this Shh expression domain contributes to the morphogenetic processes that drive the directional growth of the globular process of the FNP toward the lateral nasal process and MxP, in part by regulating cell proliferation in the facial mesenchyme. The nature of the induction mechanism that we discovered suggests that the process of fusion of the facial primordia is intrinsically buffered against producing maladaptive morphologies, such as clefts of the primary palate, because there appears to be little opportunity for variation to occur during expansion of the Shh expression domain in the ectoderm of the facial primordia. Ultimately, these results might explain why this period of development constitutes a phylotypic stage of facial development among amniotes.
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Affiliation(s)
- Diane Hu
- Department of Orthopaedic Surgery, San Francisco General Hospital, Orthopaedic Trauma Institute, The University of California at San Francisco, School of Medicine, San Francisco, CA 94110, USA
| | - Nathan M Young
- Department of Orthopaedic Surgery, San Francisco General Hospital, Orthopaedic Trauma Institute, The University of California at San Francisco, School of Medicine, San Francisco, CA 94110, USA
| | - Xin Li
- Department of Orthopaedic Surgery, San Francisco General Hospital, Orthopaedic Trauma Institute, The University of California at San Francisco, School of Medicine, San Francisco, CA 94110, USA National Key Laboratory of Bio-Macromolecule, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanhua Xu
- Department of Orthopaedic Surgery, San Francisco General Hospital, Orthopaedic Trauma Institute, The University of California at San Francisco, School of Medicine, San Francisco, CA 94110, USA Epitomizes, Inc., 1418 Moganshan Road, Hangzhou, Zhejiang 310011, China
| | - Benedikt Hallgrímsson
- Department of Anatomy and Cell Biology, University of Calgary, McCaig Institute for Bone and Joint Health, Calgary, Alberta, Canada T2N 4N1
| | - Ralph S Marcucio
- Department of Orthopaedic Surgery, San Francisco General Hospital, Orthopaedic Trauma Institute, The University of California at San Francisco, School of Medicine, San Francisco, CA 94110, USA
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80
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Kugler MC, Joyner AL, Loomis CA, Munger JS. Sonic hedgehog signaling in the lung. From development to disease. Am J Respir Cell Mol Biol 2015; 52:1-13. [PMID: 25068457 DOI: 10.1165/rcmb.2014-0132tr] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Over the past two decades, the secreted protein sonic hedgehog (SHH) has emerged as a critical morphogen during embryonic lung development, regulating the interaction between epithelial and mesenchymal cell populations in the airway and alveolar compartments. There is increasing evidence that the SHH pathway is active in adult lung diseases such as pulmonary fibrosis, asthma, chronic obstructive pulmonary disease, and lung cancer, which raises two questions: (1) What role does SHH signaling play in these diseases? and (2) Is it a primary driver of the disease or a response (perhaps beneficial) to the primary disturbance? In this review we aim to fill the gap between the well-studied period of embryonic lung development and the adult diseased lung by reviewing the hedgehog (HH) pathway during the postnatal period and in adult uninjured and injured lungs. We elucidate the similarities and differences in the epithelial-mesenchymal interplay during the fibrosis response to injury in lung compared with other organs and present a critical appraisal of tools and agents available to evaluate HH signaling.
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81
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Rodenfels J, Lavrynenko O, Ayciriex S, Sampaio JL, Carvalho M, Shevchenko A, Eaton S. Production of systemically circulating Hedgehog by the intestine couples nutrition to growth and development. Genes Dev 2015; 28:2636-51. [PMID: 25452274 PMCID: PMC4248294 DOI: 10.1101/gad.249763.114] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Rodenfels et al. show that the Drosophila intestine responds to nutrient availability by regulating production of a circulating lipoprotein-associated form of Hedgehog (Hh). Levels of circulating Hh tune the rates of growth and developmental timing in a coordinated fashion. Circulating Hh is especially important during starvation, when it is also required for mobilization of fat body triacylglycerol stores. In Drosophila larvae, growth and developmental timing are regulated by nutrition in a tightly coordinated fashion. The networks that couple these processes are far from understood. Here, we show that the intestine responds to nutrient availability by regulating production of a circulating lipoprotein-associated form of the signaling protein Hedgehog (Hh). Levels of circulating Hh tune the rates of growth and developmental timing in a coordinated fashion. Circulating Hh signals to the fat body to control larval growth. It regulates developmental timing by controlling ecdysteroid production in the prothoracic gland. Circulating Hh is especially important during starvation, when it is also required for mobilization of fat body triacylglycerol (TAG) stores. Thus, we demonstrate that Hh, previously known only for its local morphogenetic functions, also acts as a lipoprotein-associated endocrine hormone, coordinating the response of multiple tissues to nutrient availability.
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Affiliation(s)
- Jonathan Rodenfels
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Oksana Lavrynenko
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Sophie Ayciriex
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Julio L Sampaio
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Maria Carvalho
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Andrej Shevchenko
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Suzanne Eaton
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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82
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Zhulyn O, Nieuwenhuis E, Liu YC, Angers S, Hui CC. Ptch2 shares overlapping functions with Ptch1 in Smo regulation and limb development. Dev Biol 2015; 397:191-202. [DOI: 10.1016/j.ydbio.2014.10.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 10/04/2014] [Accepted: 10/27/2014] [Indexed: 10/24/2022]
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83
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Cohen M, Page KM, Perez-Carrasco R, Barnes CP, Briscoe J. A theoretical framework for the regulation of Shh morphogen-controlled gene expression. Development 2014; 141:3868-78. [PMID: 25294939 PMCID: PMC4197706 DOI: 10.1242/dev.112573] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
How morphogen gradients govern the pattern of gene expression in developing tissues is not well understood. Here, we describe a statistical thermodynamic model of gene regulation that combines the activity of a morphogen with the transcriptional network it controls. Using Sonic hedgehog (Shh) patterning of the ventral neural tube as an example, we show that the framework can be used together with the principled parameter selection technique of approximate Bayesian computation to obtain a dynamical model that accurately predicts tissue patterning. The analysis indicates that, for each target gene regulated by Gli, which is the transcriptional effector of Shh signalling, there is a neutral point in the gradient, either side of which altering the Gli binding affinity has opposite effects on gene expression. This explains recent counterintuitive experimental observations. The approach is broadly applicable and provides a unifying framework to explain the temporospatial pattern of morphogen-regulated gene expression.
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Affiliation(s)
- Michael Cohen
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Karen M Page
- Department of Mathematics and CoMPLEX, University College London, Gower Street, London WC1E 6BT, UK
| | - Ruben Perez-Carrasco
- Department of Mathematics and CoMPLEX, University College London, Gower Street, London WC1E 6BT, UK
| | - Chris P Barnes
- Department of Cell and Developmental Biology and Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - James Briscoe
- MRC-National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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84
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Differentiation Potential of Human Bone Marrow Mesenchymal Stem Cells into Motorneuron-like Cells on Electrospun Gelatin Membrane. J Mol Neurosci 2014; 55:845-53. [DOI: 10.1007/s12031-014-0437-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/07/2014] [Indexed: 12/22/2022]
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85
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Issman-Zecharya N, Schuldiner O. The PI3K Class III Complex Promotes Axon Pruning by Downregulating a Ptc-Derived Signal via Endosome-Lysosomal Degradation. Dev Cell 2014; 31:461-73. [DOI: 10.1016/j.devcel.2014.10.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 09/08/2014] [Accepted: 10/22/2014] [Indexed: 01/20/2023]
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86
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Miyake A, Chitose T, Kamei E, Murakami A, Nakayama Y, Konishi M, Itoh N. Fgf16 is required for specification of GABAergic neurons and oligodendrocytes in the zebrafish forebrain. PLoS One 2014; 9:e110836. [PMID: 25357195 PMCID: PMC4214708 DOI: 10.1371/journal.pone.0110836] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 09/24/2014] [Indexed: 11/18/2022] Open
Abstract
Fibroblast growth factor (Fgf) signaling plays crucial roles in various developmental processes including those in the brain. We examined the role of Fgf16 in the formation of the zebrafish brain. The knockdown of fgf16 decreased cell proliferation in the forebrain and midbrain. fgf16 was also essential for development of the ventral telencephalon and diencephalon, whereas fgf16 was not required for dorsoventral patterning in the midbrain. fgf16 was additionally required for the specification and differentiation of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes, but not for those of glutamatergic neurons in the forebrain. Cross talk between Fgf and Hedgehog (Hh) signaling was critical for the specification of GABAergic interneurons and oligodendrocytes. The expression of fgf16 in the forebrain was down-regulated by the inhibition of Hh and Fgf19 signaling, but not by that of Fgf3/Fgf8 signaling. The fgf16 morphant phenotype was similar to that of the fgf19 morphant and embryos blocked Hh signaling. The results of the present study indicate that Fgf16 signaling, which is regulated by the downstream pathways of Hh-Fgf19 in the forebrain, is involved in forebrain development.
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Affiliation(s)
- Ayumi Miyake
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
- * E-mail:
| | - Tatsuya Chitose
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
| | - Eriko Kamei
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
| | - Atsuko Murakami
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
| | - Yoshiaki Nakayama
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
| | - Morichika Konishi
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
| | - Nobuyuki Itoh
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
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87
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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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88
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Integration of signals along orthogonal axes of the vertebrate neural tube controls progenitor competence and increases cell diversity. PLoS Biol 2014; 12:e1001907. [PMID: 25026549 PMCID: PMC4098999 DOI: 10.1371/journal.pbio.1001907] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/05/2014] [Indexed: 12/21/2022] Open
Abstract
FGF gates competence to generate Floor Plate and Neural Crest in response to Shh and BMP signals by controlling expression of the transcription factor Nkx1.2. A relatively small number of signals are responsible for the variety and pattern of cell types generated in developing embryos. In part this is achieved by exploiting differences in the concentration or duration of signaling to increase cellular diversity. In addition, however, changes in cellular competence—temporal shifts in the response of cells to a signal—contribute to the array of cell types generated. Here we investigate how these two mechanisms are combined in the vertebrate neural tube to increase the range of cell types and deliver spatial control over their location. We provide evidence that FGF signaling emanating from the posterior of the embryo controls a change in competence of neural progenitors to Shh and BMP, the two morphogens that are responsible for patterning the ventral and dorsal regions of the neural tube, respectively. Newly generated neural progenitors are exposed to FGF signaling, and this maintains the expression of the Nk1-class transcription factor Nkx1.2. Ventrally, this acts in combination with the Shh-induced transcription factor FoxA2 to specify floor plate cells and dorsally in combination with BMP signaling to induce neural crest cells. As development progresses, the intersection of FGF with BMP and Shh signals is interrupted by axis elongation, resulting in the loss of Nkx1.2 expression and allowing the induction of ventral and dorsal interneuron progenitors by Shh and BMP signaling to supervene. Hence a similar mechanism increases cell type diversity at both dorsal and ventral poles of the neural tube. Together these data reveal that tissue morphogenesis produces changes in the coincidence of signals acting along orthogonal axes of the neural tube and this is used to define spatial and temporal transitions in the competence of cells to interpret morphogen signaling. During embryonic development different cell types arise at different times and places. This diversity is produced by a relatively small number of signals and depends, at least in part, on changes in the way cells respond to each signal. One example of this so-called change in “competence” is found in the vertebrate spinal cord where a signal, Sonic Hedgehog (Shh), induces a glial cell type known as floor plate (FP) at early developmental times, while the same signal later induces specific types of neurons. Here, we dissected the molecular mechanism underlying the change in competence, and found that another signal, FGF, is involved through its control of the transcription factor Nkx1.2. In embryos, Shh and FGF are produced perpendicular to one another and FP is induced where the two signals intersect. The position of this intersection changes as the embryo elongates and this determines the place and time FP is produced. A similar strategy also appears to apply to another cell type, neural crest. In this case, the intersection of FGF with BMP signal is crucial. Together the data provide new insight into the spatiotemporal control of cell type specification during development of the vertebrate spinal cord.
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89
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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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90
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Yue S, Tang LY, Tang Y, Tang Y, Shen QH, Ding J, Chen Y, Zhang Z, Yu TT, Zhang YE, Cheng SY. Requirement of Smurf-mediated endocytosis of Patched1 in sonic hedgehog signal reception. eLife 2014; 3. [PMID: 24925320 PMCID: PMC4080449 DOI: 10.7554/elife.02555] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 06/10/2014] [Indexed: 01/17/2023] Open
Abstract
Cell surface reception of Sonic hedgehog (Shh) must ensure that the graded morphogenic signal is interpreted accordingly in neighboring cells to specify tissue patterns during development. Here, we report endocytic sorting signals for the receptor Patched1 (Ptch1), comprising two 'PPXY' motifs, that direct it to degradation in lysosomes. These signals are recognized by two HECT-domain ubiquitin E3 ligases, Smurf1 and Smurf2, which are induced by Shh and become enriched in Caveolin-1 lipid rafts in association with Ptch1. Smurf-mediated endocytic turnover of Ptch1 is essential for its clearance from the primary cilium and pathway activation. Removal of both Smurfs completely abolishes the ability of Shh to sustain the proliferation of postnatal granule cell precursors in the cerebellum. These findings reveal a novel step in the Shh pathway activation as part of the Ptch1 negative feedback loop that precisely controls the signaling output in response to Shh gradient signal.
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Affiliation(s)
- Shen Yue
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Liu-Ya Tang
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Ying Tang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Yi Tang
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Qiu-Hong Shen
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Jie Ding
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Yan Chen
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Zengdi Zhang
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Ting-Ting Yu
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Ying E Zhang
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Steven Y Cheng
- Department of Developmental Genetics, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
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91
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Butí E, Mesquita D, Araújo SJ. Hedgehog is a positive regulator of FGF signalling during embryonic tracheal cell migration. PLoS One 2014; 9:e92682. [PMID: 24651658 PMCID: PMC3961400 DOI: 10.1371/journal.pone.0092682] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 02/25/2014] [Indexed: 11/18/2022] Open
Abstract
Cell migration is a widespread and complex process that is crucial for morphogenesis and for the underlying invasion and metastasis of human cancers. During migration, cells are steered toward target sites by guidance molecules that induce cell direction and movement through complex intracellular mechanisms. The spatio-temporal regulation of the expression of these guidance molecules is of extreme importance for both normal morphogenesis and human disease. One way to achieve this precise regulation is by combinatorial inputs of different transcription factors. Here we used Drosophila melanogaster mutants with migration defects in the ganglionic branches of the tracheal system to further clarify guidance regulation during cell migration. By studying the cellular consequences of overactivated Hh signalling, using ptc mutants, we found that Hh positively regulates Bnl/FGF levels during embryonic stages. Our results show that Hh modulates cell migration non-autonomously in the tissues surrounding the action of its activity. We further demonstrate that the Hh signalling pathway regulates bnl expression via Stripe (Sr), a zinc-finger transcription factor with homology to the Early Growth Response (EGR) family of vertebrate transcription factors. We propose that Hh modulates embryonic cell migration by participating in the spatio-temporal regulation of bnl expression in a permissive mode. By doing so, we provide a molecular link between the activation of Hh signalling and increased chemotactic responses during cell migration.
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Affiliation(s)
- Elisenda Butí
- Developmental Biology Department, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona, Spain
- Cell and Developmental Biology Programme, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - Duarte Mesquita
- Developmental Biology Department, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona, Spain
- Cell and Developmental Biology Programme, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - Sofia J. Araújo
- Developmental Biology Department, Institute of Molecular Biology of Barcelona (IBMB-CSIC), Barcelona, Spain
- Cell and Developmental Biology Programme, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- * E-mail:
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92
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Jakobs P, Exner S, Schürmann S, Pickhinke U, Bandari S, Ortmann C, Kupich S, Schulz P, Hansen U, Seidler DG, Grobe K. Scube2 enhances proteolytic Shh processing from the surface of Shh-producing cells. J Cell Sci 2014; 127:1726-37. [PMID: 24522195 DOI: 10.1242/jcs.137695] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
All morphogens of the Hedgehog (Hh) family are synthesized as dual-lipidated proteins, which results in their firm attachment to the surface of the cell in which they were produced. Thus, Hh release into the extracellular space requires accessory protein activities. We suggested previously that the proteolytic removal of N- and C-terminal lipidated peptides (shedding) could be one such activity. More recently, the secreted glycoprotein Scube2 (signal peptide, cubulin domain, epidermal-growth-factor-like protein 2) was also implicated in the release of Shh from the cell membrane. This activity strictly depended on the CUB domains of Scube2, which derive their name from the complement serine proteases and from bone morphogenetic protein-1/tolloid metalloproteinases (C1r/C1s, Uegf and Bmp1). CUB domains function as regulators of proteolytic activity in these proteins. This suggested that sheddases and Scube2 might cooperate in Shh release. Here, we confirm that sheddases and Scube2 act cooperatively to increase the pool of soluble bioactive Shh, and that Scube2-dependent morphogen release is unequivocally linked to the proteolytic processing of lipidated Shh termini, resulting in truncated soluble Shh. Thus, Scube2 proteins act as protease enhancers in this setting, revealing newly identified Scube2 functions in Hh signaling regulation.
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Affiliation(s)
- Petra Jakobs
- The Institute for Physiological Chemistry and Pathobiochemistry, Westfälische Wilhelms Universität Münster, Waldeyerstrasse 15, D-48149 Münster, Germany
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93
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Kim WK, Kim D, Cui J, Jang HH, Kim KS, Lee HJ, Kim SU, Ahn SM. Secretome analysis of human oligodendrocytes derived from neural stem cells. PLoS One 2014; 9:e84292. [PMID: 24392122 PMCID: PMC3879300 DOI: 10.1371/journal.pone.0084292] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/13/2013] [Indexed: 01/17/2023] Open
Abstract
In this study, we investigated the secretome of human oligodendrocytes (F3.Olig2 cells) generated from human neural stem cells by transduction with the gene encoding the Olig2 transcription factor. Using mRNA sequencing and protein cytokine arrays, we identified a number of biologically important secretory proteins whose expression has not been previously reported in oligodendrocytes. We found that F3.Olig2 cells secrete IL-6, PDGF-AA, GRO, GM-CSF, and M-CSF, and showed prominent expression of their corresponding receptors. Co-expression of ligands and receptors suggests that autocrine signaling loops may play important roles in both differentiation and maintenance of oligodendrocytes. We also found that F3.Olig2 cells secrete matrix metalloproteinases and matrix metalloproteinase-associated proteins associated with functional competence of oligodendrocytes. The results of our secretome analysis provide insights into the functional and molecular details of human oligodendrocytes. To the best of our knowledge, this is the first systematic analysis of the secretome of oligodendrocytes.
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Affiliation(s)
- Woo Kyung Kim
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
- Asan Center for Cancer Genome Discovery, Asan Institute for Life Science, Ulsan University College of Medicine, Asan Medical Center, Seoul, Korea
- BRC Genome Research Center, Bio Research Complex, Incheon, Korea
| | - Deokhoon Kim
- Asan Center for Cancer Genome Discovery, Asan Institute for Life Science, Ulsan University College of Medicine, Asan Medical Center, Seoul, Korea
| | - Jun Cui
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - Ho Hee Jang
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - Kwang Sei Kim
- Medical Research Institute, Chung-Ang University College of Medicine, Seoul, Korea
| | - Hong Jun Lee
- Medical Research Institute, Chung-Ang University College of Medicine, Seoul, Korea
| | - Seung U. Kim
- Medical Research Institute, Chung-Ang University College of Medicine, Seoul, Korea
- Division of Neurology, Department of Medicine, UBC Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail: (SUK); (SMA)
| | - Sung-Min Ahn
- Asan Center for Cancer Genome Discovery, Asan Institute for Life Science, Ulsan University College of Medicine, Asan Medical Center, Seoul, Korea
- Department of Oncology, Ulsan University College of Medicine, Seoul, Korea
- * E-mail: (SUK); (SMA)
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94
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Gli protein activity is controlled by multisite phosphorylation in vertebrate Hedgehog signaling. Cell Rep 2013; 6:168-181. [PMID: 24373970 DOI: 10.1016/j.celrep.2013.12.003] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 11/07/2013] [Accepted: 12/03/2013] [Indexed: 01/17/2023] Open
Abstract
Gli proteins are transcriptional effectors of the Hedgehog (Hh) pathway in both normal development and cancer. We describe a program of multisite phosphorylation that regulates the conversion of Gli proteins into transcriptional activators. In the absence of Hh ligands, Gli activity is restrained by the direct phosphorylation of six conserved serine residues by protein kinase A (PKA), a master negative regulator of the Hh pathway. Activation of signaling leads to a global remodeling of the Gli phosphorylation landscape: the PKA target sites become dephosphorylated, while a second cluster of sites undergoes phosphorylation. The pattern of Gli phosphorylation can regulate Gli transcriptional activity in a graded fashion, suggesting a phosphorylation-based mechanism for how a gradient of Hh signaling in a morphogenetic field can be converted into a gradient of transcriptional activity.
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95
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Hong M, Krauss RS. Rescue of holoprosencephaly in fetal alcohol-exposed Cdon mutant mice by reduced gene dosage of Ptch1. PLoS One 2013; 8:e79269. [PMID: 24244464 PMCID: PMC3823703 DOI: 10.1371/journal.pone.0079269] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 09/25/2013] [Indexed: 11/18/2022] Open
Abstract
Holoprosencephaly (HPE) is a commonly occurring developmental defect in which midline patterning of the forebrain and midface is disrupted. Sonic hedgehog (SHH) signaling is required during multiple stages of rostroventral midline development, and heterozygous mutations in SHH pathway components are associated with HPE. However, clinical presentation of HPE is highly variable, and carriers of heterozygous mutations often lack apparent defects. It is therefore thought that such mutations must interact with more common modifiers, genetic and/or environmental. We have modeled this scenario in mice. Cdon mutant mice have a largely subthreshold defect in SHH signaling, rendering them sensitive to a wide spectrum of HPE phenotypes by additional hits that are themselves insufficient to produce HPE, including transient in utero exposure to ethanol. These variable HPE phenotypes may arise in embryos that fail to reach a threshold level of SHH signaling at a specific developmental stage. To provide evidence for this possibility, here we tested the effect of removing one copy of the negative regulator Ptch1 from Cdon(-/-) embryos and compared their response to ethanol with that of Cdon(-/-);Ptch1(+/+) embryos. Ptch1 heterozygosity decreased the penetrance of HPE in this system by >75%. The major effect of reduced Ptch1 gene dosage was on penetrance, as those Cdon(-/-);Ptch1(+/-) embryos that displayed HPE did not show major differences in phenotype from Cdon(-/-);Ptch1(+/+) embryos with ethanol-induced HPE. Our findings are consistent with the notion that even in an etiologically complex model of HPE, the level of SHH pathway activity is rate-limiting. Furthermore, the clinical outcome of an individual carrying a SHH pathway mutation will likely reflect the sum effect of both deleterious and protective modifier alleles and their interaction with non-genetic risk factors like fetal alcohol exposure.
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Affiliation(s)
- Mingi Hong
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Robert S. Krauss
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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96
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Wilson NH, Stoeckli ET. Sonic hedgehog regulates its own receptor on postcrossing commissural axons in a glypican1-dependent manner. Neuron 2013; 79:478-91. [PMID: 23931997 DOI: 10.1016/j.neuron.2013.05.025] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2013] [Indexed: 11/28/2022]
Abstract
Upon reaching their intermediate target, the floorplate, commissural axons acquire responsiveness to repulsive guidance cues, allowing the axons to exit the midline and adopt a contralateral, longitudinal trajectory. The molecular mechanisms that regulate this switch from attraction to repulsion remain poorly defined. Here, we show that the heparan sulfate proteoglycan Glypican1 (GPC1) is required as a coreceptor for the Shh-dependent induction of Hedgehog-interacting protein (Hhip) in commissural neurons. In turn, Hhip is required for postcrossing axons to respond to a repulsive anteroposterior Shh gradient. Thus, Shh is a cue with dual function. In precrossing axons it acts as an attractive guidance molecule in a transcription-independent manner. At the same time, Shh binds to GPC1 to induce the expression of its own receptor, Hhip, which mediates the repulsive response of postcrossing axons to Shh. Our study characterizes a molecular mechanism by which navigating axons switch their responsiveness at intermediate targets.
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Affiliation(s)
- Nicole H Wilson
- Institute of Molecular Life Sciences, Neuroscience Center Zurich, University of Zurich, CH-8057 Zurich, Switzerland
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97
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Vadasz S, Marquez J, Tulloch M, Shylo NA, García-Castro MI. Pax7 is regulated by cMyb during early neural crest development through a novel enhancer. Development 2013; 140:3691-702. [PMID: 23942518 DOI: 10.1242/dev.088328] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The neural crest (NC) is a migratory population of cells unique to vertebrates that generates many diverse derivatives. NC cells arise during gastrulation at the neural plate border (NPB), which is later elevated as the neural folds (NFs) form and fuse in the dorsal region of the closed neural tube, from where NC cells emigrate. In chick embryos, Pax7 is an early marker, and necessary component of NC development. Unlike other early NPB markers, which are co-expressed in lateral ectoderm, medial neural plate or posterior-lateral mesoderm, Pax7 early expression seems more restricted to the NPB. However, the molecular mechanisms controlling early Pax7 expression remain poorly understood. Here, we identify a novel enhancer of Pax7 in avian embryos that replicates the expression of Pax7 associated with early NC development. Expression from this enhancer is found in early NPB, NFs and early emigrating NC, but unlike Pax7, which is also expressed in mesodermal derivatives, this enhancer is not active in somites. Further analysis demonstrates that cMyb is able to interact with this enhancer and modulates reporter and endogenous early Pax7 expression; thus, cMyb is identified as a novel regulator of Pax7 in early NC development.
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Affiliation(s)
- Stephanie Vadasz
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
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98
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Vazin T, Ashton RS, Conway A, Rode NA, Lee SM, Bravo V, Healy KE, Kane RS, Schaffer DV. The effect of multivalent Sonic hedgehog on differentiation of human embryonic stem cells into dopaminergic and GABAergic neurons. Biomaterials 2013; 35:941-8. [PMID: 24172856 DOI: 10.1016/j.biomaterials.2013.10.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 10/05/2013] [Indexed: 01/24/2023]
Abstract
Stem cell differentiation is regulated by complex repertoires of signaling ligands which often use multivalent interactions, where multiple ligands tethered to one entity interact with multiple cellular receptors to yield oligomeric complexes. One such ligand is Sonic hedgehog (Shh), whose posttranslational lipid modifications and assembly into multimers enhance its biological potency, potentially through receptor clustering. Investigations of Shh typically utilize recombinant, monomeric protein, and thus the impact of multivalency on ligand potency is unexplored. Among its many activities, Shh is required for ventralization of the midbrain and forebrain and is therefore critical for the development of midbrain dopaminergic (mDA) and forebrain gamma-aminobutyric acid (GABA) inhibitory neurons. We have designed multivalent biomaterials presenting Shh in defined spatial arrangements and investigated the role of Shh valency in ventral specification of human embryonic stem cells (hESCs) into these therapeutically relevant cell types. Multivalent Shh conjugates with optimal valencies, compared to the monomeric Shh, increased the percentages of neurons belonging to mDA or forebrain GABAergic fates from 33% to 60% or 52% to 86%, respectively. Thus, multivalent Shh bioconjugates can enhance neuronal lineage commitment of pluripotent stem cells and thereby facilitate efficient derivation of neurons that could be used to treat Parkinson's and epilepsy patients.
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Affiliation(s)
- Tandis Vazin
- Chemical and Biomolecular Engineering, and The Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720, USA
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99
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Holtz AM, Peterson KA, Nishi Y, Morin S, Song JY, Charron F, McMahon AP, Allen BL. Essential role for ligand-dependent feedback antagonism of vertebrate hedgehog signaling by PTCH1, PTCH2 and HHIP1 during neural patterning. Development 2013; 140:3423-34. [PMID: 23900540 DOI: 10.1242/dev.095083] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Hedgehog (HH) signaling is essential for vertebrate and invertebrate embryogenesis. In Drosophila, feedback upregulation of the HH receptor Patched (PTC; PTCH in vertebrates), is required to restrict HH signaling during development. By contrast, PTCH1 upregulation is dispensable for early HH-dependent patterning in mice. Unique to vertebrates are two additional HH-binding antagonists that are induced by HH signaling, HHIP1 and the PTCH1 homologue PTCH2. Although HHIP1 functions semi-redundantly with PTCH1 to restrict HH signaling in the developing nervous system, a role for PTCH2 remains unresolved. Data presented here define a novel role for PTCH2 as a ciliary localized HH pathway antagonist. While PTCH2 is dispensable for normal ventral neural patterning, combined removal of PTCH2- and PTCH1-feedback antagonism produces a significant expansion of HH-dependent ventral neural progenitors. Strikingly, complete loss of PTCH2-, HHIP1- and PTCH1-feedback inhibition results in ectopic specification of ventral cell fates throughout the neural tube, reflecting constitutive HH pathway activation. Overall, these data reveal an essential role for ligand-dependent feedback inhibition of vertebrate HH signaling governed collectively by PTCH1, PTCH2 and HHIP1.
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Affiliation(s)
- Alexander M Holtz
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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100
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Myers BR, Sever N, Chong YC, Kim J, Belani JD, Rychnovsky S, Bazan JF, Beachy PA. Hedgehog pathway modulation by multiple lipid binding sites on the smoothened effector of signal response. Dev Cell 2013; 26:346-57. [PMID: 23954590 DOI: 10.1016/j.devcel.2013.07.015] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 01/06/2023]
Abstract
Hedgehog (Hh) signaling during development and in postembryonic tissues requires activation of the 7TM oncoprotein Smoothened (Smo) by mechanisms that may involve endogenous lipidic modulators. Exogenous Smo ligands previously identified include the plant sterol cyclopamine (and its therapeutically useful synthetic mimics) and hydroxylated cholesterol derivatives (oxysterols); Smo is also highly sensitive to cellular sterol levels. The relationships between these effects are unclear because the relevant Smo structural determinants are unknown. We identify the conserved extracellular cysteine-rich domain (CRD) as the site of action for oxysterols on Smo, involving residues structurally analogous to those contacting the Wnt lipid adduct in the homologous Frizzled CRD; this modulatory effect is distinct from that of cyclopamine mimics, from Hh-mediated regulation, and from the permissive action of cellular sterol pools. These results imply that Hh pathway activity is sensitive to lipid binding at several Smo sites, suggesting mechanisms for tuning by multiple physiological inputs.
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Affiliation(s)
- Benjamin R Myers
- Department of Biochemistry, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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