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Kokkorakis N, Douka K, Nalmpanti A, Politis PK, Zagoraiou L, Matsas R, Gaitanou M. Mirk/Dyrk1B controls ventral spinal cord development via Shh pathway. Cell Mol Life Sci 2024; 81:70. [PMID: 38294527 PMCID: PMC10830675 DOI: 10.1007/s00018-023-05097-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 12/14/2023] [Accepted: 12/17/2023] [Indexed: 02/01/2024]
Abstract
Cross-talk between Mirk/Dyrk1B kinase and Sonic hedgehog (Shh)/Gli pathway affects physiology and pathology. Here, we reveal a novel role for Dyrk1B in regulating ventral progenitor and neuron subtypes in the embryonic chick spinal cord (SC) via the Shh pathway. Using in ovo gain-and-loss-of-function approaches at E2, we report that Dyrk1B affects the proliferation and differentiation of neuronal progenitors at E4 and impacts on apoptosis specifically in the motor neuron (MN) domain. Especially, Dyrk1B overexpression decreases the numbers of ventral progenitors, MNs, and V2a interneurons, while the pharmacological inhibition of endogenous Dyrk1B kinase activity by AZ191 administration increases the numbers of ventral progenitors and MNs. Mechanistically, Dyrk1B overexpression suppresses Shh, Gli2 and Gli3 mRNA levels, while conversely, Shh, Gli2 and Gli3 transcription is increased in the presence of Dyrk1B inhibitor AZ191 or Smoothened agonist SAG. Most importantly, in phenotype rescue experiments, SAG restores the Dyrk1B-mediated dysregulation of ventral progenitors. Further at E6, Dyrk1B affects selectively the medial lateral motor neuron column (LMCm), consistent with the expression of Shh in this region. Collectively, these observations reveal a novel regulatory function of Dyrk1B kinase in suppressing the Shh/Gli pathway and thus affecting ventral subtypes in the developing spinal cord. These data render Dyrk1B a possible therapeutic target for motor neuron diseases.
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Affiliation(s)
- N Kokkorakis
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Hellenic Pasteur Institute, Athens, Greece
- Division of Animal and Human Physiology, Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - K Douka
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Hellenic Pasteur Institute, Athens, Greece
| | - A Nalmpanti
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Hellenic Pasteur Institute, Athens, Greece
- Athens International Master's Programme in Neurosciences, Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - P K Politis
- Center of Basic Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- School of Medicine, European University Cyprus, Nicosia, Cyprus
| | - L Zagoraiou
- School of Medicine, European University Cyprus, Nicosia, Cyprus
| | - R Matsas
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Hellenic Pasteur Institute, Athens, Greece
| | - M Gaitanou
- Laboratory of Cellular and Molecular Neurobiology-Stem Cells, Hellenic Pasteur Institute, Athens, Greece.
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Murphy KP, Pathak B, Peiro JL, Oria M. Time Course Transcriptome Analysis of Spina Bifida Progression in Fetal Rats. Brain Sci 2021; 11:brainsci11121593. [PMID: 34942894 PMCID: PMC8699677 DOI: 10.3390/brainsci11121593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/09/2021] [Accepted: 11/24/2021] [Indexed: 12/22/2022] Open
Abstract
A better understanding of the transcriptomic modifications that occur in spina bifida may lead to identify mechanisms involved in the progression of spina bifida in utero and the development of new therapeutic strategies that aid in spinal cord regeneration after surgical interventions. In this study, RNA-sequencing was used to identify differentially expressed genes in fetal spinal cords from rats with retinoic acid-induced spina bifida at E15, E17, and E20. Gene ontology, KEGG, and protein–protein interaction analysis were conducted to predict pathways involved in the evolution of the disease. Approximately 3000, 1000 and 300 genes were differentially expressed compared to the control groups at E15, E17 and E20, respectively. Overall, the results suggest common alterations in certain pathways between gestational time points, such as upregulation in p53 and sonic hedgehog signaling at E15 and E17 and downregulation in the myelin sheath at E17 and E20. However, there were other modifications specific to gestational time points, including skeletal muscle development at E15, downregulated glucose metabolism at E17, and upregulated inflammation at E20. In conclusion, this work provides evidence that gestational age during spina bifida repair may be a significant variable to consider during the development of new regenerative therapeutics approaches.
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Affiliation(s)
- Kendall P. Murphy
- Department of Orthopaedic Surgery, University of Cincinnati, Cincinnati, OH 45267, USA;
- Center for Fetal and Placental Research, Division of Pediatric General and Thoracic Surgery, Cincinnati Children’s Hospital and Medical Center, Cincinnati, OH 45229, USA; (B.P.); (J.L.P.)
| | - Bedika Pathak
- Center for Fetal and Placental Research, Division of Pediatric General and Thoracic Surgery, Cincinnati Children’s Hospital and Medical Center, Cincinnati, OH 45229, USA; (B.P.); (J.L.P.)
| | - Jose L. Peiro
- Center for Fetal and Placental Research, Division of Pediatric General and Thoracic Surgery, Cincinnati Children’s Hospital and Medical Center, Cincinnati, OH 45229, USA; (B.P.); (J.L.P.)
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Marc Oria
- Center for Fetal and Placental Research, Division of Pediatric General and Thoracic Surgery, Cincinnati Children’s Hospital and Medical Center, Cincinnati, OH 45229, USA; (B.P.); (J.L.P.)
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45267, USA
- Correspondence: ; Tel.: +513-636-3494
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Nam H, Jeon S, An H, Yoo J, Lee HJ, Lee SK, Lee S. Critical roles of ARHGAP36 as a signal transduction mediator of Shh pathway in lateral motor columnar specification. eLife 2019; 8:46683. [PMID: 31305241 PMCID: PMC6658197 DOI: 10.7554/elife.46683] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/14/2019] [Indexed: 01/20/2023] Open
Abstract
During spinal cord development, Sonic hedgehog (Shh), secreted from the floor plate, plays an important role in the production of motor neurons by patterning the ventral neural tube, which establishes MN progenitor identity. It remains unknown, however, if Shh signaling plays a role in generating columnar diversity of MNs that connect distinct target muscles. Here, we report that Shh, expressed in MNs, is essential for the formation of lateral motor column (LMC) neurons in vertebrate spinal cord. This novel activity of Shh is mediated by its downstream effector ARHGAP36, whose expression is directly induced by the MN-specific transcription factor complex Isl1-Lhx3. Furthermore, we found that AKT stimulates the Shh activity to induce LMC MNs through the stabilization of ARHGAP36 proteins. Taken together, our data reveal that Shh, secreted from MNs, plays a crucial role in generating MN diversity via a regulatory axis of Shh-AKT-ARHGAP36 in the developing mouse spinal cord.
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Affiliation(s)
- Heejin Nam
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea
| | - Shin Jeon
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea.,Neuroscience Section, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health and Science Uiversity, Portland, United States
| | - Hyejin An
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jaeyoung Yoo
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hyo-Jong Lee
- College of Pharmacy and Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gyungnam, Republic of Korea
| | - Soo-Kyung Lee
- Neuroscience Section, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health and Science Uiversity, Portland, United States.,Vollum Institute, Oregon Health and Science University, Portland, United States
| | - Seunghee Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea
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Juraver-Geslin HA, Durand BC. Early development of the neural plate: new roles for apoptosis and for one of its main effectors caspase-3. Genesis 2015; 53:203-24. [PMID: 25619400 DOI: 10.1002/dvg.22844] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/07/2015] [Indexed: 12/12/2022]
Abstract
Despite its tremendous complexity, the vertebrate nervous system emerges from a homogenous layer of neuroepithelial cells, the neural plate. Its formation relies on the time- and space-controlled progression of developmental programs. Apoptosis is a biological process that removes superfluous and potentially dangerous cells and is implemented through the activation of a molecular pathway conserved during evolution. Apoptosis and an unconventional function of one of its main effectors, caspase-3, contribute to the patterning and growth of the neuroepithelium. Little is known about the intrinsic and extrinsic cues controlling activities of the apoptotic machinery during development. The BarH-like (Barhl) proteins are homeodomain-containing transcription factors. The observations in Caenorhabditis elegans, Xenopus, and mice document that Barhl proteins act in cell survival and as cell type-specific regulators of a caspase-3 function that limits neural progenitor proliferation. In this review, we discuss the roles and regulatory modes of the apoptotic machinery in the development of the neural plate. We focus on the Barhl2, the Sonic Hedgehog, and the Wnt pathways and their activities in neural progenitor survival and proliferation.
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Affiliation(s)
- Hugo A Juraver-Geslin
- Department of Basic Science, Craniofacial Biology, College of Dentistry, New York University, New York, New York
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Trowe MO, Zhao L, Weiss AC, Christoffels V, Epstein DJ, Kispert A. Inhibition of Sox2-dependent activation of Shh in the ventral diencephalon by Tbx3 is required for formation of the neurohypophysis. Development 2013; 140:2299-309. [PMID: 23674600 DOI: 10.1242/dev.094524] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tbx2 and Tbx3 are two highly related members of the T-box transcription factor gene family that regulate patterning and differentiation of a number of tissue rudiments in the mouse. Both genes are partially co-expressed in the ventral diencephalon and the infundibulum; however, a functional requirement in murine pituitary development has not been reported. Here, we show by genetic lineage tracing that Tbx2(+) cells constitute the precursor population of the neurohypophysis. However, Tbx2 is dispensable for neurohypophysis development as revealed by normal formation of this organ in Tbx2-deficient mice. By contrast, loss of Tbx3 from the ventral diencephalon results in a failure to establish the Tbx2(+) domain in this region, and a lack of evagination of the infundibulum and formation of the neurohypophysis. Rathke's pouch is severely hypoplastic, exhibits defects in dorsoventral patterning, and degenerates after E12.5. In Tbx3-deficient embryos, the ventral diencephalon is hyperproliferative and displays an abnormal cellular architecture, probably resulting from a failure to repress transcription of Shh. We further show that Tbx3 and Tbx2 repress Shh by sequestering the SRY box-containing transcription factor Sox2 away from a Shh forebrain enhancer (SBE2), thus preventing its activation. These data suggest that Tbx3 is required in the ventral diencephalon to establish a Shh(-) domain to allow formation of the infundibulum.
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Affiliation(s)
- Mark-Oliver Trowe
- Institut für Molekularbiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
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Kim JY, Choi SY, Kim H, Sun W. Effect of Strychinine, a Glycine Inhibitor, on the Programmed Cell Death of Motoneurons during the Chick Development. Exp Neurobiol 2012; 20:176-80. [PMID: 22355262 PMCID: PMC3268151 DOI: 10.5607/en.2011.20.4.176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 05/17/2011] [Indexed: 11/19/2022] Open
Abstract
In this study, we report that the treatment of strychinine (STR), an inhibitor of glycine receptor, induced premature onset of programmed cell death (PCD) of developing chick motoneurons (MNs). Treatment of STR on E4 chick embryo increased the apoptosis of MN on E5 when MN PCD does not occur normally. On the other hand, treatment of STR from E3 or E5 for 24 hours did not significantly influence the extent of MN PCD, indicating that the STR effect is developmental stage-specific. However, the expression of glycine receptor isoform was low on E3-4, and other glycine receptor antagonists did not exhibit PCD-promoting activity, suggesting that the STR action on PCD is not related to the glycine receptor activation. Identification of the target molecule for STR action may provide novel mechanism how the onset of developmental PCD is regulated.
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Affiliation(s)
- Joo Yeon Kim
- Department of Anatomy, BK21 Program, Korea University College of Medicine, Seoul 136-705, Korea
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8
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From cell death to viral replication: the diverse functions of the membrane-associated FKBP38. Curr Opin Pharmacol 2011; 11:348-53. [PMID: 21514222 DOI: 10.1016/j.coph.2011.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 03/25/2011] [Accepted: 03/30/2011] [Indexed: 01/27/2023]
Abstract
FKBP38 is in many ways an exceptional member of the FK506-binding proteins. The calmodulin-regulated activity of FKBP38 for instance is unique within this protein family. The activated FKBP38 participates in apoptosis signaling by inhibiting the anti-apoptotic Bcl-2. Beyond this role in programmed cell death, FKBP38 seems to be involved in very different cellular processes that do not necessarily depend on the FKBP domain. These functions involve regulation of the kinase mTOR, regulation of neural tube formation, regulation of cellular hypoxia response, but also Hepatitis C virus replication. Pharmacological targeting of FKBP38 might therefore prove a successful strategy for intervention in different FKBP38-dependent processes, including programmed cell death in cancer or neurodegenerative diseases.
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9
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Elashry MI, Otto A, Matsakas A, El-Morsy SE, Jones L, Anderson B, Patel K. Axon and muscle spindle hyperplasia in the myostatin null mouse. J Anat 2011; 218:173-84. [PMID: 21208206 DOI: 10.1111/j.1469-7580.2010.01327.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Germline deletion of the myostatin gene results in hyperplasia and hypertrophy of the tension-generating (extrafusal) fibres in skeletal muscle. As this gene is expressed predominantly in myogenic tissues it offers an excellent model with which to investigate the quantitative relationship between muscle and axonal development. Here we show that skeletal muscle hyperplasia in myostatin null mouse is accompanied by an increase in nerve fibres in major nerves of both the fore- and hindlimbs. We show that axons within these nerves undergo hypertrophy. Furthermore, we provide evidence that the age-related neural atrophic process is delayed in the absence of myostatin. Finally, we show that skeletal muscle hyperplasia in the myostatin null mouse is accompanied by an increase in the number of muscle spindles (also called stretch receptors or proprioceptors). However, our work demonstrates that the mechanisms regulating intrafusal fibre hyperplasia and hypertrophy differ from those that control the aetiology of extrafusal fibres.
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Affiliation(s)
- Mohamed I Elashry
- School of Biological Sciences, Hopkins Building, University of Reading, Reading, UK
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10
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Wang M, Mominoki K, Kinutani M, Wang Z, Kobayashi N, Shimokawa T, Nabeka H, Fujiwara T, Matsuda S. Developmental delay in islet-1-positive motor neurons in chick spina bifida. J Vet Med Sci 2010; 73:447-52. [PMID: 21127393 DOI: 10.1292/jvms.10-0385] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spina bifida aperta (SBA) is a congenital malformation of the spinal cord with complications such as spinal ataxia and bowel and bladder dysfunction. We have developed a chick model with surgery-induced SBA that shows spinal ataxia after hatching. In the present study, motor neurons in the early stages in chicks with and without SBA were observed by immunohistochemical staining with a monoclonal antibody against Islet-1, a motor neuron marker. Delay in migration and maturation of motor neurons was observed in SBA. Although the final numbers of Islet-1-positive neurons in these two groups were not different, a defect in the production and elimination of excess motor neurons in the early developmental stages in the SBA group may be involved in the pathological mechanism of the motor complications of this disease.
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Affiliation(s)
- Min Wang
- Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Ehime, Japan
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11
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Bragina O, Sergejeva S, Serg M, Zarkovsky T, Maloverjan A, Kogerman P, Zarkovsky A. Smoothened agonist augments proliferation and survival of neural cells. Neurosci Lett 2010; 482:81-5. [PMID: 20600593 DOI: 10.1016/j.neulet.2010.06.068] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 06/22/2010] [Accepted: 06/23/2010] [Indexed: 11/26/2022]
Abstract
Sonic hedgehog signaling pathway is important in developmental processes like dorsoventral neural tube patterning, neural stem cell proliferation and neuronal and glial cell survival. Shh is also implicated in the regulation of the adult hippocampal neurogenesis. Recently, nonpeptidyl Smoothened activators of the Shh pathway have been identified. The aim of this study was to investigate the effects of chlorobenzothiophene-containing molecule, Smo agonist (SAG), which has been shown to activate Shh signaling pathway, in neurogenesis and neuronal survival in in vitro and in vivo models. Our in vitro experiments showed that SAG induces increased expression of Gli1 mRNA, transcriptional target and mediator of Shh signal. In vitro experiments also demonstrated that SAG in low-nanomolar concentrations induces proliferation of neuronal and glial precursors without affecting the differentiation pattern of newly produced cells. In contrast to Shh, SAG did not induce neurotoxicity in neuronal cultures. The SAG and Shh treatment also promoted the survival of newly generated neural cells in the dentate gyrus after their intracerebroventricular administration to adult rats. We propose that SAG and similar compounds represent attractive molecules to be developed for treatment of disorders where stimulation of the generation and survival of new neural cells would be beneficial.
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Affiliation(s)
- Olga Bragina
- Institute of Clinical Medicine, Tallinn University of Technology, Estonia
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12
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Expression of neuronal antigens and related ventral and dorsal proteins in the normal spinal cord and a surgically induced open neural tube defect of the spine in chick embryos: an immunohistochemical study. Childs Nerv Syst 2010; 26:627-36. [PMID: 19949802 DOI: 10.1007/s00381-009-1049-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The aims of this study were to elucidate the processes of neuronal differentiation and ventrodorsal patterning in the spinal cord of the chick embryo from embryonic day (E) 3 to E17 and to study the effect of a prenatal spinal open neural tube defect (ONTD) on these processes. METHOD Expression patterns of neuronal antigens (neuronal nuclear antigen, neurofilament-associated protein (NAP), and synaptophysin) and related ventral markers [sonic hedgehog, paired box gene (PAX)6, and islet-1], and dorsal markers (bone morphogenetic protein, Notch homolog 1, and PAX7) were investigated in the normal spinal cord and in a surgically induced spinal ONTD in chick embryos. Four normal and ONTD chick embryos were used for each antigen group. RESULT & CONCLUSION There were no differences in the expression of neuronal and ventrodorsal markers between the control and ONTD groups. NAP and synaptophysin were useful for identifying dorsal structures in the distorted anatomy of the ONTD chicks.
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Abstract
The hypothalamus is a region of the diencephalon with particularly complex patterning. Sonic hedgehog (Shh), encoding a protein with key developmental roles, shows a peculiar and dynamic diencephalic expression pattern. Here, we use transgenic strategies and in vitro experiments to test the hypothesis that Shh expressed in the diencephalic neuroepithelium (neural Shh) coordinates tissue growth and patterning in the hypothalamus. Our results show that neural Shh coordinates anteroposterior and dorsoventral patterning in the hypothalamus and in the diencephalon-telencephalon junction. Neural Shh also coordinates mediolateral hypothalamic patterning, since it is necessary for the lateral hypothalamus to attain proper size and is required for the specification of hypocretin/orexin cells. Finally, neural Shh is necessary to maintain expression of differentiation markers including survival factor Foxb1.
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Cho A, Ko HW, Eggenschwiler JT. FKBP8 cell-autonomously controls neural tube patterning through a Gli2- and Kif3a-dependent mechanism. Dev Biol 2008; 321:27-39. [PMID: 18590716 DOI: 10.1016/j.ydbio.2008.05.558] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 04/17/2008] [Accepted: 05/21/2008] [Indexed: 12/24/2022]
Affiliation(s)
- Ahryon Cho
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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15
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Bohl D, Liu S, Blanchard S, Hocquemiller M, Haase G, Heard JM. Directed evolution of motor neurons from genetically engineered neural precursors. Stem Cells 2008; 26:2564-75. [PMID: 18635866 DOI: 10.1634/stemcells.2008-0371] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Stem cell-based therapies hold therapeutic promise for degenerative motor neuron diseases, such as amyotrophic lateral sclerosis, and for spinal cord injury. Fetal neural progenitors present less risk of tumor formation than embryonic stem cells but inefficiently differentiate into motor neurons, in line with their low expression of motor neuron-specific transcription factors and poor response to soluble external factors. To overcome this limitation, we genetically engineered fetal rat spinal cord neurospheres to express the transcription factors HB9, Nkx6.1, and Neurogenin2. Enforced expression of the three factors rendered neural precursors responsive to Sonic hedgehog and retinoic acid and directed their differentiation into cholinergic motor neurons that projected axons and formed contacts with cocultured myotubes. When transplanted in the injured adult rat spinal cord, a model of acute motor neuron degeneration, the engineered precursors transiently proliferated, colonized the ventral horn, expressed motor neuron-specific differentiation markers, and projected cholinergic axons in the ventral root. We conclude that genetic engineering can drive the differentiation of fetal neural precursors into motor neurons that efficiently engraft in the spinal cord. The strategy thus holds promise for cell replacement in motor neuron and related diseases. Disclosure of potential conflicts of interest is found at the end of this article.
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Affiliation(s)
- Delphine Bohl
- Département Neuroscience, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U622, Unité Rétrovirus et Transfert Génétique, Paris, France.
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16
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Bond C, Tang Y, Podlasek CA. Neural influences on sonic hedgehog and apoptosis in the rat penis. Biol Reprod 2008; 78:947-56. [PMID: 18256331 DOI: 10.1095/biolreprod.107.064766] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The role of sonic hedgehog (SHH) in maintaining corpora cavernosal morphology in the adult penis has been established; however, the mechanism of how SHH itself is regulated remains unclear. Since decreased SHH protein is a cause of smooth muscle apoptosis and erectile dysfunction (ED) in the penis, and SHH treatment can suppress cavernous nerve (CN) injury-induced apoptosis, the question of how SHH signaling is regulated is significant. It is likely that neural input is involved in this process since two models of neuropathy-induced ED exhibit decreased SHH protein and increased apoptosis in the penis. We propose the hypothesis that SHH abundance in the corpora cavernosa is regulated by SHH signaling in the pelvic ganglia, neural activity, or neural transport of a trophic factor from the pelvic ganglia to the corpora. We have examined each of these potential mechanisms. SHH inhibition in the penis shows a 12-fold increase in smooth muscle apoptosis. SHH inhibition in the pelvic ganglia causes significantly increased apoptosis (1.3-fold) and decreased SHH protein (1.1-fold) in the corpora cavernosa. SHH protein is not transported by the CN. Colchicine treatment of the CN resulted in significantly increased smooth muscle apoptosis (1.2-fold) and decreased SHH protein (1.3-fold) in the penis. Lidocaine treatment of the CN caused a similar increase in apoptosis (1.6-fold) and decrease in SHH protein (1.3-fold) in the penis. These results show that neural activity and a trophic factor from the pelvic ganglia/CN are necessary to regulate SHH protein and smooth muscle abundance in the penis.
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Affiliation(s)
- Christopher Bond
- Department of Urology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Martinez-Chinchilla P, Riobo NA. Purification and bioassay of hedgehog ligands for the study of cell death and survival. Methods Enzymol 2008; 446:189-204. [PMID: 18603123 DOI: 10.1016/s0076-6879(08)01611-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Hedgehog (Hh) family of secreted ligands-composed of Sonic Hedgehog (Shh), Indian Hedgehog (Ihh), and Desert Hedgehog (Dhh)-possesses many roles during embryonic development, adult homeostasis, and cancer. The specific functions of the Hh proteins are intertwined with their requirement as survival factors in Hh-responsive cells. However, studies designed to dissect the anti-apoptotic role of Hhs have been hindered by the lack of simple approaches to purify large quantities of recombinant ligands in the average laboratory setting because of the natural modifications of these proteins with palmitic acid and cholesterol. In this chapter, we provide a comprehensive protocol for the expression of Shh, Ihh, and Dhh in Escherichia coli as fusion proteins with calmodulin-binding peptide to allow easy and rapid purification. The ligands are engineered with a new N-terminus containing two isoleucine residues to provide an essential hydrophobic interphase for achieving high biologic activity. The protocol includes a detailed description of a method for determination of the specific activity of the generated proteins by use of a cell culture-based luciferase approach.
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Affiliation(s)
- Pilar Martinez-Chinchilla
- Department of Biochemistry and Molecular Biology and Kimmel Cancer Center, Thomas Jefferson University
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18
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Guan W, Wang G, Scott SA, Condic ML. Shh influences cell number and the distribution of neuronal subtypes in dorsal root ganglia. Dev Biol 2007; 314:317-28. [PMID: 18190905 DOI: 10.1016/j.ydbio.2007.11.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 11/21/2007] [Accepted: 11/26/2007] [Indexed: 11/29/2022]
Abstract
The molecular mechanisms responsible for specifying the dorsal-ventral pattern of neuronal identities in dorsal root ganglia (DRG) are unclear. Here we demonstrate that Sonic hedgehog (Shh) contributes to patterning early DRG cells. In vitro, Shh increases both proliferation and programmed cell death (PCD). Increasing Shh in vivo enhances PCD in dorsal DRG, while inducing greater proliferation ventrally. In such animals, markers characteristic of ventral sensory neurons are expanded to more dorsal positions. Conversely, reducing Shh function results in decreased proliferation of progenitors in the ventral region and decreased expression of the ventral marker trkC. Later arising trkA(+) afferents make significant pathfinding errors in animals with reduced Shh function, suggesting that accurate navigation of later arising growth cones requires either Shh itself or early arising, Shh-dependent afferents. These results indicate that Shh can regulate both cell number and the distribution of cell types in DRG, thereby playing an important role in the specification, patterning and pathfinding of sensory neurons.
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Affiliation(s)
- Wei Guan
- Interdepartmental Program in Neuroscience, University of Utah, School of Medicine, 20 North 1900 East, Salt Lake City, UT 84132-3401, USA
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Wong RLY, Wlodarczyk BJ, Min KS, Scott ML, Kartiko S, Yu W, Merriweather MY, Vogel P, Zambrowicz BP, Finnell RH. Mouse Fkbp8 activity is required to inhibit cell death and establish dorso-ventral patterning in the posterior neural tube. Hum Mol Genet 2007; 17:587-601. [PMID: 18003640 DOI: 10.1093/hmg/ddm333] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Rebecca Lee Yean Wong
- Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, The Texas A&M University System Health Science Center, 2121 W. Holcombe Blvd, Houston, TX 77030, USA.
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20
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Abstract
The hedgehog pathway is a major regulator of embryonic development, and mutations that decrease its activity are known to be associated with severe defects in nervous system development. Recent evidence suggests hedgehog continues to function in adult tissue, normal as well as diseased, by regulating both cell proliferation and the production of growth and angiogenic factors. In the adult nervous system, this dual ability is especially important in regulating the behavior of neural stem and progenitor cells. This review summarizes information connecting hedgehog signaling and neural diseases, including neurodegenerative disorders and brain tumors, particularly medulloblastoma. We also describe the discovery and utility of small molecule agonists and antagonists of this pathway and their potential as novel types of therapeutics.
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21
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Banks GB, Chamberlain JS. Relevance of motoneuron specification and programmed cell death in embryos to therapy of ALS. ACTA ACUST UNITED AC 2006; 75:294-304. [PMID: 16425251 DOI: 10.1002/bdrc.20051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The molecular cues that generate spinal motoneurons in early embryonic development are well defined. Motoneurons are generated in excess and consequently undergo a natural period of programmed cell death. Although it is not known exactly how motoneurons compete for survival in embryonic development, it is hypothesized that they rely on the ability to access limited amounts of trophic factors from peripheral tissues, a process that is tightly regulated by skeletal muscle activity. Attempts to elucidate the molecular mechanisms that underlie motoneuron generation and programmed cell death in embryos have led to various effective strategies for treating injury and disease in animal models. Such studies provide great hope for the amelioration of human amyotrophic lateral sclerosis (ALS), a devastating progressive motoneuron degenerative disease. Here we review the clinical relevance of studying motoneuron specification and death during embryonic development.
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Affiliation(s)
- Glen B Banks
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA.
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22
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Abstract
The notion of "morphogens" is an important one in developmental biology. By definition, a morphogen is a molecule that emanates from a specific set of cells that is present in a concentration gradient and that specifies the fate of each cell along this gradient. The strongest candidate morphogens are members of the transforming growth factor-beta (TGF-beta), Hedgehog (Hh), and Wnt families. While these morphogens have been extensively described as differentiation inducers, some reports also suggest their possible involvement in cell death and cell survival. It is frequently speculated that the cell death induction that is found associated with experimental removal of morphogens is the manifestation of abnormal differentiation signals. However, several recent reports have raised controversy about this death by default, suggesting that cell death regulation is an active process for shaping tissues and organs. In this review, we will present morphogens, with a specific emphasis on Sonic Hedgehog, a mammalian member of the Hh family, not as a positive regulators of cell differentiation but as key regulators of cell survival.
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Affiliation(s)
- Patrick Mehlen
- Laboratoire Apoptose, Cancer et Développement, Equipe labelisée La Ligue, CNRS FRE2870, Centre Léon Bérard, 69008 Lyon, France.
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23
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Akazawa C, Tsuzuki H, Nakamura Y, Sasaki Y, Ohsaki K, Nakamura S, Arakawa Y, Kohsaka S. The upregulated expression of sonic hedgehog in motor neurons after rat facial nerve axotomy. J Neurosci 2005; 24:7923-30. [PMID: 15356205 PMCID: PMC6729937 DOI: 10.1523/jneurosci.1784-04.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Nerve injury leads to the induction of a large number of genes to repair the damage and to restore synaptic transmission. We have attempted to identify molecules whose mRNA expression is altered in response to facial nerve axotomy. Here we report that facial nerve axotomy upregulates Sonic hedgehog (Shh) and its receptor Smoothened (Smo) in facial motor neurons of adult rats, whereas facial nerve axotomy does not upregulate mRNA of Shh or Smo in neonatal rats. We tested whether overexpression of Shh in facial motor neurons of axotomized neonatal rats may promote neuronal survival. Adenovirus-mediated overexpression of Shh, but not that of beta-galactosidase, transiently rescues axotomy-induced neuronal cell death for 3-5 d after axotomy. Finally, the pharmacological inhibitor of Shh signaling, cyclopamine, induces motor neuron death in adult rats after axotomy. These results suggest that Shh plays a regulatory role in nerve injury.
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Affiliation(s)
- Chihiro Akazawa
- Department of Neurochemistry, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan.
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24
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Offner N, Duval N, Jamrich M, Durand B. The pro-apoptotic activity of a vertebrate Bar-like homeobox gene plays a key role in patterning the Xenopus neural plate by limiting the number of chordin- and shh-expressing cells. Development 2005; 132:1807-18. [PMID: 15772136 DOI: 10.1242/dev.01712] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Targeted disruption of effectors molecules of the apoptotic pathway have demonstrated the occurrence and magnitude of early programmed cell death (EPCD), a form of apoptosis that affects proliferating and newly differentiated cells in vertebrates, and most dramatically cells of the central nervous system (CNS). Little is known about the molecular pathways controlling apoptosis at these early developmental stages, as the roles of EPCD during patterning of the developing nervous system. We describe a new function, in Xenopus neurodevelopment, for a highly conserved homeodomain protein Barhl2. Barhl2 promotes apoptosis in the Xenopus neuroectoderm and mesoderm, acting as a transcriptional repressor, through a mechanism that cannot be attributed to an unspecific cellular stress response. We show that the pro-apoptotic activity of Barhl2 is essential during normal neural plate formation as it limits the number of chordin- and Xshh-expressing cells in the prospective notochord and floorplate, which act as organizing centers. Our findings show that Barhl2 is part of a pathway regulating EPCD. They also provide evidence that apoptosis plays an important role in regulating the size of organizing centers.
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Affiliation(s)
- Nicolas Offner
- Unité Rétrovirus et Transfert Génétique, INSERM (U622). Institut Pasteur, Paris, France
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25
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De Zio D, Giunta L, Corvaro M, Ferraro E, Cecconi F. Expanding roles of programmed cell death in mammalian neurodevelopment. Semin Cell Dev Biol 2005; 16:281-94. [PMID: 15797838 DOI: 10.1016/j.semcdb.2004.12.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Programmed cell death is an orchestrated form of cell death in which cells are actively involved in their own demise. During neural development in mammals, many progenitor cells, immature cells or differentiated cells undergo the most clearly characterized type of cell death, apoptosis. Several pathways of apoptosis have been linked to neural development, but according to the numerous and striking phenotypes observed when apoptotic genes are inactivated, the mitochondrial death-route is the most important pathway in this context. Here, we discuss the relative importance of pro-growth/pro-death factors in the control of neural tissue development. We also discuss the impact of studying programmed cell death in development in order to better understand the basis of several human diseases and embryonic defects of the nervous system.
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Affiliation(s)
- Daniela De Zio
- Dulbecco Telethon Institute, Department of Biology, University of Rome Tor Vergata, via della Ricerca Scientifica, 00133 Rome, Italy
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26
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Yeo W, Gautier J. Early neural cell death: dying to become neurons. Dev Biol 2004; 274:233-44. [PMID: 15385155 DOI: 10.1016/j.ydbio.2004.07.026] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 07/23/2004] [Accepted: 07/28/2004] [Indexed: 10/26/2022]
Abstract
The importance of programmed cell death (PCD) during vertebrate development has been well established. During the development of the nervous system in particular, neurotrophic cell death in innervating neurons matches the number of neurons to the size of their target field. However, PCD also occurs during earlier stages of neural development, within populations of proliferating neural precursors and newly postmitotic neuroblasts, all of which are not yet fully differentiated. This review addresses early neural PCD, which is distinct from neurotrophic death in differentiated neurons. Although early neural PCD is observed in a range of organisms, from Caenorhabditis elegans to mouse, the role and the regulation of early neural PCD are not well understood. The regulation of early neural PCD can be inferred from the function of factors such as bone morphogenetic proteins (BMPs), Wnts, fibroblast growth factors (FGFs), and Sonic Hedgehog (Shh), which regulate both early neural development and PCD occurring in other developmental processes. Cell number control, removal of damaged or misspecified cells (spatially or temporally), and selection are the proposed roles early neural PCDs play during neural development. Data from developmental PCD in C. elegans and Drosophila provide insights into the possible signaling pathways integrating PCD with other processes during early neural development and the roles they might play.
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Affiliation(s)
- Weeteck Yeo
- Department of Genetics and Development, Columbia University, New York, NY 10032, USA
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27
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Abstract
Cell signaling plays a key role in the development of all multicellular organisms. Numerous studies have established the importance of Hedgehog signaling in a wide variety of regulatory functions during the development of vertebrate and invertebrate organisms. Several reviews have discussed the signaling components in this pathway, their various interactions, and some of the general principles that govern Hedgehog signaling mechanisms. This review focuses on the developing systems themselves, providing a comprehensive survey of the role of Hedgehog signaling in each of these. We also discuss the increasing significance of Hedgehog signaling in the clinical setting.
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Affiliation(s)
- Andrew P McMahon
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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28
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Sussman CR, Davies JE, Miller RH. Extracellular and intracellular regulation of oligodendrocyte development: roles of Sonic hedgehog and expression of E proteins. Glia 2002; 40:55-64. [PMID: 12237843 DOI: 10.1002/glia.10114] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recent advances in understanding oligodendrocyte development have revealed the importance of both extra- and intracellular molecules in regulating the induction, survival, and proliferation of early oligodendrocyte progenitors. The signaling molecule Sonic hedgehog (Shh) is critical for normal development of oligodendrocytes, although the precise influences of Shh on cells of the oligodendrocyte lineage are unclear. The present study shows that Shh increased the number of oligodendrocyte precursors in both pure cultures of oligodendrocyte precursors and mixed cultures from embryonic rat spinal cord. In pure precursor cultures Shh increased cell survival. In mixed cultures, Shh increased both the survival and proliferation of oligodendrocyte precursors in a concentration dependent manner. One intracellular consequence of exposure to Shh is the activation of transcription factors in oligodendrocyte lineage cells, which are critical for oligodendrocyte development, helix-loop-helix (HLH) transcription factors, Olig1 and 2. In many cases, HLH proteins such as Olig1 and Olig2 heterodimerize with other HLH proteins, such as members of the E subfamily, which are critical regulators of cell proliferation and differentiation. Immature (A2B5(+)) and more mature (O4(+)) rat oligodendrocyte precursors in dissociated cell culture expressed Olig1 as well as E proteins, HEB and E2A. Similarly, cells bearing the morphology of oligodendrocyte precursors expressed both Olig1 and HEB or E2A. We propose that E2A and/or HEB, possibly in combination with Olig1 and 2, are critical components of oligodendrogenesis and may regulate cell survival, proliferation, and fate decisions in the oligodendrocyte lineage.
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Affiliation(s)
- Caroline R Sussman
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4975, USA.
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29
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Yao HHC, Whoriskey W, Capel B. Desert Hedgehog/Patched 1 signaling specifies fetal Leydig cell fate in testis organogenesis. Genes Dev 2002; 16:1433-40. [PMID: 12050120 PMCID: PMC186321 DOI: 10.1101/gad.981202] [Citation(s) in RCA: 344] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Establishment of the steroid-producing Leydig cell lineage is an event downstream of Sry that is critical for masculinization of mammalian embryos. Neither the origin of fetal Leydig cell precursors nor the signaling pathway that specifies the Leydig cell lineage is known. Based on the sex-specific expression patterns of Desert Hedgehog (Dhh) and its receptor Patched 1 (Ptch1) in XY gonads, we investigated the potential role of DHH/PTCH1 signaling in the origin and specification of fetal Leydig cells. Analysis of Dhh(-/-) XY gonads revealed that differentiation of fetal Leydig cells was severely defective. Defects in Leydig cell differentiation in Dhh(-/-) XY gonads did not result from failure of cell migration from the mesonephros, thought to be a possible source of Leydig cell precursors. Nor did DHH/PTCH1 signaling appear to be involved in the proliferation or survival of fetal Leydig precursors in the interstitium of the XY gonad. Instead, our results suggest that DHH/PTCH1 signaling triggers Leydig cell differentiation by up-regulating Steroidogenic Factor 1 and P450 Side Chain Cleavage enzyme expression in Ptch1-expressing precursor cells located outside testis cords.
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Affiliation(s)
- Humphrey Hung-Chang Yao
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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30
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Capdevila J, Izpisúa Belmonte JC. Patterning mechanisms controlling vertebrate limb development. Annu Rev Cell Dev Biol 2002; 17:87-132. [PMID: 11687485 DOI: 10.1146/annurev.cellbio.17.1.87] [Citation(s) in RCA: 324] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vertebrate limb buds are embryonic structures for which much molecular and cellular data are known regarding the mechanisms that control pattern formation during development. Specialized regions of the developing limb bud, such as the zone of polarizing activity (ZPA), the apical ectodermal ridge (AER), and the non-ridge ectoderm, direct and coordinate the development of the limb bud along the anterior-posterior (AP), dorsal-ventral (DV), and proximal-distal (PD) axes, giving rise to a stereotyped pattern of elements well conserved among tetrapods. In recent years, specific gene functions have been shown to mediate the organizing and patterning activities of the ZPA, the AER, and the non-ridge ectoderm. The analysis of these gene functions has revealed the existence of complex interactions between signaling pathways operated by secreted factors of the HH, TGF-beta/BMP, WNT, and FGF superfamilies, which interact with many other genetic networks to control limb positioning, outgrowth, and patterning. The study of limb development has helped to establish paradigms for the analysis of pattern formation in many other embryonic structures and organs.
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Affiliation(s)
- J Capdevila
- Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
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31
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Dahmane N, Sánchez P, Gitton Y, Palma V, Sun T, Beyna M, Weiner H, Ruiz i Altaba A. The Sonic Hedgehog-Gli pathway regulates dorsal brain growth and tumorigenesis. Development 2001; 128:5201-12. [PMID: 11748155 DOI: 10.1242/dev.128.24.5201] [Citation(s) in RCA: 310] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mechanisms that regulate the growth of the brain remain unclear. We show that Sonic hedgehog (Shh) is expressed in a layer-specific manner in the perinatal mouse neocortex and tectum, whereas the Gli genes, which are targets and mediators of SHH signaling, are expressed in proliferative zones. In vitro and in vivo assays show that SHH is a mitogen for neocortical and tectal precursors and that it modulates cell proliferation in the dorsal brain. Together with its role in the cerebellum, our findings indicate that SHH signaling unexpectedly controls the development of the three major dorsal brain structures. We also show that a variety of primary human brain tumors and tumor lines consistently express the GLI genes and that cyclopamine, a SHH signaling inhibitor, inhibits the proliferation of tumor cells. Using the in vivo tadpole assay system, we further show that misexpression of GLI1 induces CNS hyperproliferation that depends on the activation of endogenous Gli1 function. SHH-GLI signaling thus modulates normal dorsal brain growth by controlling precursor proliferation, an evolutionarily important and plastic process that is deregulated in brain tumors.
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Affiliation(s)
- N Dahmane
- Skirball Institute of Biomolecular Medicine, Developmental Genetics Program and Department of Cell Biology, NYU School of Medicine, 540 First Avenue, New York, NY 10016, USA
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32
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Affiliation(s)
- P W Ingham
- Centre for Developmental Genetics, University of Sheffield, Sheffield S10 2TN, UK.
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33
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Charrier JB, Lapointe F, Le Douarin NM, Teillet MA. Anti-apoptotic role of Sonic hedgehog protein at the early stages of nervous system organogenesis. Development 2001; 128:4011-20. [PMID: 11641224 DOI: 10.1242/dev.128.20.4011] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In vertebrates the neural tube, like most of the embryonic organs, shows discreet areas of programmed cell death at several stages during development. In the chick embryo, cell death is dramatically increased in the developing nervous system and other tissues when the midline cells, notochord and floor plate, are prevented from forming by excision of the axial-paraxial hinge (APH), i.e. caudal Hensen’s node and rostral primitive streak, at the 6-somite stage (Charrier, J. B., Teillet, M.-A., Lapointe, F. and Le Douarin, N. M. (1999). Development126, 4771-4783). In this paper we demonstrate that one day after APH excision, when dramatic apoptosis is already present in the neural tube, the latter can be rescued from death by grafting a notochord or a floor plate fragment in its vicinity. The neural tube can also be recovered by transplanting it into a stage-matched chick embryo having one of these structures. In addition, cells engineered to produce Sonic hedgehog protein (SHH) can mimic the effect of the notochord and floor plate cells in in situ grafts and transplantation experiments. SHH can thus counteract a built-in cell death program and thereby contribute to organ morphogenesis, in particular in the central nervous system.
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Affiliation(s)
- J B Charrier
- Institut d'Embryologie Cellulaire et Moléculaire, CNRS FRE2160, 49bis Avenue de la Belle Gabrielle, 94736 Nogent-sur-Marne Cedex, France
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34
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Izraeli S, Lowe LA, Bertness VL, Campaner S, Hahn H, Kirsch IR, Kuehn MR. Genetic evidence that Sil is required for the Sonic Hedgehog response pathway. Genesis 2001; 31:72-7. [PMID: 11668681 DOI: 10.1002/gene.10004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The Sil gene encodes a cytosolic protein required for mouse embryonic midline and left/right axial development. Based on the phenotype of Sil mutant embryos, we hypothesized that Sil may be required for the activity of Sonic Hedgehog (Shh), a secreted signaling molecule also critically important for the development of the embryonic axes and found mutated in multiple types of cancer. Here we tested the genetic interaction between Sil and the Shh pathway by generating and analyzing embryos carrying mutations in both Sil and Patched (Ptch), a Shh receptor that normally inhibits the signaling pathway in the absence of ligand and when mutated leads to constitutive activation of the pathway. We find that Sil(-/-) Ptch(-/-) embryos do not activate the Shh pathway and instead have a phenotype indistinguishable from Sil(-/-) embryos, in which there is a loss of activity of Shh. These results provide genetic evidence that Sil is an essential component of the Shh response, acting downstream to Ptch.
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MESH Headings
- Animals
- Cell Death/genetics
- Crosses, Genetic
- Embryo, Mammalian/embryology
- Embryo, Mammalian/metabolism
- Epistasis, Genetic
- Female
- Gene Deletion
- Gene Expression Regulation, Developmental
- Genotype
- Head/embryology
- Hedgehog Proteins
- In Situ Hybridization
- In Situ Nick-End Labeling
- Intracellular Signaling Peptides and Proteins
- Male
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Mice
- Mice, Knockout
- Oncogene Proteins, Fusion
- Patched Receptors
- Patched-1 Receptor
- Proteins/genetics
- Proteins/metabolism
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Receptors, Cell Surface
- Signal Transduction
- Trans-Activators/metabolism
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35
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Chen W, Burgess S, Hopkins N. Analysis of the zebrafishsmoothenedmutant reveals conserved and divergent functions of hedgehog activity. Development 2001; 128:2385-96. [PMID: 11493557 DOI: 10.1242/dev.128.12.2385] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Despite extensive studies, there are still many unanswered questions regarding the mechanism of hedgehog signaling and the phylogenic conservation of hedgehog function in vertebrates. For example, whether hedgehog signaling in vertebrates requires smoothened is unclear, and the role of hedgehog activity in zebrafish is controversial. We show that inactivation of smoothened by retroviral insertions in zebrafish results in defects that are characteristic of hedgehog deficiencies, including abnormalities in body size, the central nervous system, adaxial mesoderm, cartilage and pectoral fins. We demonstrate that, as in Drosophila, vertebrate smoothened is essential for hedgehog signaling, and functions upstream of protein kinase A. Further analysis of neural tube defects revealed the absence of lateral floor plate and secondary motoneurons, but the presence of medial floor plate and primary motoneurons in smoothened mutant embryos. Blocking maternal hedgehog signaling by cyclopamine eliminates primary motoneurons, but not medial floor plate. Interestingly, even after inhibition of maternal hedgehog activity, the midbrain dopaminergic neurons still form, and looping of the heart does not randomize in the mutants. We also found decreased proliferation and increased apoptosis in the mutants. Taken together, these data demonstrate the conserved role of vertebrate smoothened in the hedgehog signaling pathway, and reveal similarities and differences of hedgehog function between teleosts and amniotes.
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Affiliation(s)
- W Chen
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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36
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Davies JE, Miller RH. Local sonic hedgehog signaling regulates oligodendrocyte precursor appearance in multiple ventricular zone domains in the chick metencephalon. Dev Biol 2001; 233:513-25. [PMID: 11336511 DOI: 10.1006/dbio.2001.0224] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the chick metencephalon, oligodendrocyte precursors arise in distinct domains of the ventricular zone. During development, the earliest oligodendrocyte precursors appear in the metencephalic ventral ventricular zone adjacent to the midline, consistent with their location in the spinal cord. In contrast to spinal cord, however, distinct domains in the lateral and dorsal metencephalic ventricular zone subsequently generate oligodendrocyte precursors. All oligodendrogenic domains of the metencephalon appear in close apposition to regions that transiently express sonic hedgehog (Shh). Inhibition studies demonstrate a functional requirement for Shh signaling in the early appearance of metencephalic oligodendrocyte precursors, while in vitro studies suggest a dose-dependent increase in the number of oligodendrocyte precursors in response to Shh. In purified cultures of oligodendrocyte precursors, Shh promotes cell survival and proliferation, suggesting that Shh can act directly on these cells. These data suggest that Shh may be responsible for the localized appearance of oligodendrocyte precursors throughout the CNS, irrespective of the dorso-ventral neural axis.
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Affiliation(s)
- J E Davies
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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37
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Sanz-Ezquerro JJ, Tickle C. Autoregulation of Shh expression and Shh induction of cell death suggest a mechanism for modulating polarising activity during chick limb development. Development 2000; 127:4811-23. [PMID: 11044396 DOI: 10.1242/dev.127.22.4811] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The polarising region expresses the signalling molecule sonic hedgehog (Shh), and is an embryonic signalling centre essential for outgrowth and patterning of the vertebrate limb. Previous work has suggested that there is a buffering mechanism that regulates polarising activity. Little is known about how the number of Shh-expressing cells is controlled but, paradoxically, the polarising region appears to overlap with the posterior necrotic zone, a region of programmed cell death. We have investigated how Shh expression and cell death respond when levels of polarising activity are altered, and show an autoregulatory effect of Shh on Shh expression and that Shh affects cell death in the posterior necrotic zone. When we increased Shh signalling, by grafting polarising region cells or applying Shh protein beads, this led to a reduction in the endogenous Shh domain and an increase in posterior cell death. In contrast, cells in other necrotic regions of the limb bud, including the interdigital areas, were rescued from death by Shh protein. Application of Shh protein to late limb buds also caused alterations in digit morphogenesis. When we reduced the number of Shh-expressing cells in the polarising region by surgery or drug-induced killing, this led to an expansion of the Shh domain and a decrease in the number of dead cells. Furthermore, direct prevention of cell death using a retroviral vector expressing Bcl2 led to an increase in Shh expression. Finally, we provide evidence that the fate of some of the Shh-expressing cells in the polarising region is to undergo apoptosis and contribute to the posterior necrotic zone during normal limb development. Taken together, these results show that there is a buffering system that regulates the number of Shh-expressing cells and thus polarising activity during limb development. They also suggest that cell death induced by Shh could be the cellular mechanism involved. Such an autoregulatory process based on cell death could represent a general way for regulating patterning signals in embryos.
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Affiliation(s)
- J J Sanz-Ezquerro
- Department of Anatomy and Physiology, Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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38
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Krieglstein K, Richter S, Farkas L, Schuster N, Dünker N, Oppenheim RW, Unsicker K. Reduction of endogenous transforming growth factors beta prevents ontogenetic neuron death. Nat Neurosci 2000; 3:1085-90. [PMID: 11036264 DOI: 10.1038/80598] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We show that following immunoneutralization of endogenous transforming growth factors beta (TGF-beta) in the chick embryo, ontogenetic neuron death of ciliary, dorsal root and spinal motor neurons was largely prevented, and neuron losses following limb bud ablation were greatly reduced. Likewise, preventing TGF-beta signaling by treatment with a TbetaR-II fusion protein during the period of ontogenetic cell death in the ciliary ganglion rescued all neurons that normally die. TUNEL staining revealed decreased numbers of apoptotic cells following antibody treatment. Exogenous TGF-beta rescued the TGF-beta-deprived phenotype. We conclude that TGF-beta is critical in regulating ontogenetic neuron death as well as cell death following neuronal target deprivation.
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Affiliation(s)
- K Krieglstein
- Department of Anatomy, Medical Faculty, University of Saarland at Homburg/Saar, Building 61, D-66421 Homburg/Saar, Germany.
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39
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Abstract
The secreted glycoprotein Sonic hedgehog (SHH), a vertebrate homologue of the Drosophila segment polarity gene Hedgehog, is essential for the development of diverse tissues during embryogenesis. Studies of SHH function during neural tube and somite development have focused on its role in specifying the dorsoventral polarity of these structures, but a recent report by Ahlgren and Bronner-Fraser(1) supports the possibility that SHH has additional functions in cell survival and cell proliferation. Perturbation of SHH signaling after the early dorsoventral specification of the cranial neural tube leads to increased cell death in both the neural tube and the neural crest. This implies that SHH is continually required as a trophic and/or mitogenic factor during brain development, and expands the variety of cellular responses to SHH signaling. BioEssays 22:499-502, 2000.
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Affiliation(s)
- J M Britto
- Department of Anatomy, University of Cambridge, UK
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