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Zhang Y, Sung HH, Ziegler AB, Wu YC, Viais R, Sánchez-Huertas C, Kilo L, Agrican FG, Cheng YJ, Mouri K, Uemura T, Lüders J, Chien CT, Tavosanis G. Augmin complex activity fine-tunes dendrite morphology through non-centrosomal microtubule nucleation in vivo. J Cell Sci 2024:jcs.261512. [PMID: 38587100 DOI: 10.1242/jcs.261512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 04/03/2024] [Indexed: 04/09/2024] Open
Abstract
During development neurons achieve a stereotyped neuron type-specific morphology, which relies on dynamic support by microtubules (MTs). An important player is augmin which binds to existing MT filaments and recruits the γ-Tubulin Ring Complex (γ-TuRC), to form branched MTs. In cultured neurons, augmin is important for neurite formation. However, little is known about the role of augmin during neurite formation in vivo. Here, we have revisited the role of mammalian augmin in culture and then turned towards the class four Drosophila dendritic arborization (c4da) neurons. We show that MT density is maintained through augmin in cooperation with the γ-TuRC in vivo. Mutant c4da neurons show a reduction of newly emerging higher-order dendritic branches and in turn also a reduced number of their characteristic space-filling higher-order branchlets. Taken together, our data reveal a cooperative function of the augmin complex with the γ-TuRC in forming enough MTs needed for the appropriate differentiation of morphologically complex dendrites in vivo.
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Affiliation(s)
- Yun Zhang
- German center for neurodegenerative diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Hsin-Ho Sung
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Anna B Ziegler
- German center for neurodegenerative diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Ying-Chieh Wu
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Ricardo Viais
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Carlos Sánchez-Huertas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain
| | | | - Fikret-Gürkan Agrican
- German center for neurodegenerative diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Kousuke Mouri
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
- Center for Living Systems Information Science, Kyoto University, Japan
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, 11529 Taipei, Taiwan
| | - Gaia Tavosanis
- German center for neurodegenerative diseases (DZNE), Dynamics of Neuronal Circuits Group, Venusberg Campus 1 Building 99, 53127 Bonn, Germany
- LIMES Institute, University of Bonn, 53115 Bonn, Germany
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2
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Pai YL, Lin YJ, Peng WH, Huang LT, Chou HY, Wang CH, Chien CT, Chen GC. The deubiquitinase Leon/USP5 interacts with Atg1/ULK1 and antagonizes autophagy. Cell Death Dis 2023; 14:540. [PMID: 37607937 PMCID: PMC10444890 DOI: 10.1038/s41419-023-06062-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 07/21/2023] [Accepted: 08/14/2023] [Indexed: 08/24/2023]
Abstract
Accumulating evidence has shown that the quality of proteins must be tightly monitored and controlled to maintain cellular proteostasis. Misfolded proteins and protein aggregates are targeted for degradation through the ubiquitin proteasome (UPS) and autophagy-lysosome systems. The ubiquitination and deubiquitinating enzymes (DUBs) have been reported to play pivotal roles in the regulation of the UPS system. However, the function of DUBs in the regulation of autophagy remain to be elucidated. In this study, we found that knockdown of Leon/USP5 caused a marked increase in the formation of autophagosomes and autophagic flux under well-fed conditions. Genetic analysis revealed that overexpression of Leon suppressed Atg1-induced cell death in Drosophila. Immunoblotting assays further showed a strong interaction between Leon/USP5 and the autophagy initiating kinase Atg1/ULK1. Depletion of Leon/USP5 led to increased levels of Atg1/ULK1. Our findings indicate that Leon/USP5 is an autophagic DUB that interacts with Atg1/ULK1, negatively regulating the autophagic process.
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Affiliation(s)
- Yueh-Ling Pai
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - Yuchieh Jay Lin
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, 106, Taiwan
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan
| | - Wen-Hsin Peng
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - Li-Ting Huang
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, 106, Taiwan
| | - He-Yen Chou
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - Chien-Hsiang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan.
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, 106, Taiwan.
- Chemical Biology and Molecular Biophysics, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan.
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3
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Ravinther AI, Dewadas HD, Tong SR, Foo CN, Lin YE, Chien CT, Lim YM. Molecular Pathways Involved in LRRK2-Linked Parkinson’s Disease: A Systematic Review. Int J Mol Sci 2022; 23:ijms231911744. [PMID: 36233046 PMCID: PMC9569706 DOI: 10.3390/ijms231911744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/24/2022] Open
Abstract
Parkinson’s disease is one of the most common neurodegenerative diseases affecting the ageing population, with a prevalence that has doubled over the last 30 years. As the mechanism of the disease is not fully elucidated, the current treatments are unable to effectively prevent neurodegeneration. Studies have found that mutations in Leucine-rich-repeat-kinase 2 (LRRK2) are the most common cause of familial Parkinson’s disease (PD). Moreover, aberrant (higher) LRRK2 kinase activity has an influence in idiopathic PD as well. Hence, the aim of this review is to categorize and synthesize current information related to LRRK2-linked PD and present the factors associated with LRRK2 that can be targeted therapeutically. A systematic review was conducted using the databases PubMed, Medline, SCOPUS, SAGE, and Cochrane (January 2016 to July 2021). Search terms included “Parkinson’s disease”, “mechanism”, “LRRK2”, and synonyms in various combinations. The search yielded a total of 988 abstracts for initial review, 80 of which met the inclusion criteria. Here, we emphasize molecular mechanisms revealed in recent in vivo and in vitro studies. By consolidating the recent updates in the field of LRRK2-linked PD, researchers can further evaluate targets for therapeutic application.
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Affiliation(s)
- Ailyn Irvita Ravinther
- Centre for Cancer Research, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Hemaniswarri Dewi Dewadas
- Centre for Biomedical and Nutrition Research, Faculty of Science, Universiti Tunku Abdul Rahman, Kampar 31900, Perak, Malaysia
| | - Shi Ruo Tong
- Centre for Cancer Research, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
| | - Chai Nien Foo
- Centre for Cancer Research, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
- Department of Population Medicine, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
| | - Yu-En Lin
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yang Mooi Lim
- Centre for Cancer Research, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
- Department of Pre-Clinical Sciences, M. Kandiah Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Selangor, Malaysia
- Correspondence:
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4
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Li H, Sung HH, Huang YC, Cheng YJ, Yeh HF, Pi H, Giniger E, Chien CT. Fringe-positive Golgi outposts unite temporal Furin 2 convertase activity and spatial Delta signal to promote dendritic branch retraction. Cell Rep 2022; 40:111372. [PMID: 36130510 DOI: 10.1016/j.celrep.2022.111372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 07/07/2022] [Accepted: 08/25/2022] [Indexed: 11/19/2022] Open
Abstract
Golgi outposts (GOPs) in dendrites are known for their role in promoting branch extension, but whether GOPs have other functions is unclear. We found that terminal branches of Drosophila class IV dendritic arborization (C4da) neurons actively grow during the early third-instar (E3) larval stage but retract in the late third (L3) stage. Interestingly, the Fringe (Fng) glycosyltransferase localizes increasingly at GOPs in distal dendritic regions through the E3 to the L3 stage. Expression of the endopeptidase Furin 2 (Fur2), which proteolyzes and inactivates Fng, decreases from E3 to L3 in C4da neurons, thereby increasing Fng-positive GOPs in dendrites. The epidermal Delta ligand and neuronal Notch receptor, the substrate for Fng-mediated O-glycosylation, also negatively regulate dendrite growth. Fng inhibits actin dynamics in dendrites, linking dendritic branch retraction to suppression of the C4da-mediated thermal nociception response in late larval stages. Thus, Fng-positive GOPs function in dendrite retraction, which would add another function to the repertoire of GOPs in dendrite arborization.
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Affiliation(s)
- Hsun Li
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei 11529, Taiwan
| | - Hsin-Ho Sung
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Chun Huang
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hsiao-Fong Yeh
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan 33302, Taiwan
| | - Haiwei Pi
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan 33302, Taiwan
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan; Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang Ming Chiao Tung University and Academia Sinica, Taipei 11529, Taiwan; Neuroscience Program of Academia Sinica, Academia Sinica, Taipei 11529, Taiwan.
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5
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Lin YE, Lin CH, Ho EP, Ke YC, Petridi S, Elliott CJH, Sheen LY, Chien CT. Glial Nrf2 signaling mediates the neuroprotection exerted by Gastrodia elata Blume in Lrrk2-G2019S Parkinson's disease. eLife 2021; 10:73753. [PMID: 34779396 PMCID: PMC8660019 DOI: 10.7554/elife.73753] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/12/2021] [Indexed: 12/17/2022] Open
Abstract
The most frequent missense mutations in familial Parkinson's disease (PD) occur in the highly conserved LRRK2/PARK8 gene with G2019S mutation. We previously established a fly model of PD carrying the LRRK2-G2019S mutation that exhibited the parkinsonism-like phenotypes. An herbal medicine, Gastrodia elata Blume (GE), has been reported to have neuroprotective effects in toxin-induced PD models. However, the underpinning molecular mechanisms of GE beneficiary to G2019S-induced PD remain unclear. Here, we show that these G2019S flies treated with water extracts of GE (WGE) and its bioactive compounds, gastrodin and 4-HBA, displayed locomotion improvement and dopaminergic neuron protection. WGE suppressed the accumulation and hyperactivation of G2019S proteins in dopaminergic neurons and activated the antioxidation and detoxification factor Nrf2 mostly in the astrocyte-like and ensheathing glia. Glial activation of Nrf2 antagonizes G2019S-induced Mad/Smad signaling. Moreover, we treated LRRK2-G2019S transgenic mice with WGE and found that the locomotion declines, the loss of dopaminergic neurons, and the number of hyperactive microglia were restored. WGE also suppressed the hyperactivation of G2019S proteins and regulated the Smad2/3 pathways in the mice brains. We conclude that WGE prevents locomotion defects and the neuronal loss induced by G2019S mutation via glial Nrf2/Mad signaling, unveiling a potential therapeutic avenue for PD.
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Affiliation(s)
- Yu-En Lin
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan,Institute of Food Science and Technology, National Taiwan UniversityTaipeiTaiwan
| | - Chin-Hsien Lin
- Department of Neurology, National Taiwan University HospitalTaipeiTaiwan
| | - En-Peng Ho
- Department of Neurology, National Taiwan University HospitalTaipeiTaiwan
| | - Yi-Ci Ke
- Department of Neurology, National Taiwan University HospitalTaipeiTaiwan
| | - Stavroula Petridi
- Department of Clinical Neurosciences and MRC Mitochondrial Biology Unit, University of CambridgeCambridgeUnited Kingdom,Department of Biology and York Biomedical Research Institute, University of YorkYorkUnited Kingdom
| | - Christopher JH Elliott
- Department of Biology and York Biomedical Research Institute, University of YorkYorkUnited Kingdom
| | - Lee-Yan Sheen
- Institute of Food Science and Technology, National Taiwan UniversityTaipeiTaiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan,Neuroscience Program of Academia Sinica, Academia SinicaTaipeiTaiwan
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6
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Wang YH, Ding ZY, Cheng YJ, Chien CT, Huang ML. An Efficient Screen for Cell-Intrinsic Factors Identifies the Chaperonin CCT and Multiple Conserved Mechanisms as Mediating Dendrite Morphogenesis. Front Cell Neurosci 2020; 14:577315. [PMID: 33100975 PMCID: PMC7546278 DOI: 10.3389/fncel.2020.577315] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/02/2020] [Indexed: 12/25/2022] Open
Abstract
Dendritic morphology is inextricably linked to neuronal function. Systematic large-scale screens combined with genetic mapping have uncovered several mechanisms underlying dendrite morphogenesis. However, a comprehensive overview of participating molecular mechanisms is still lacking. Here, we conducted an efficient clonal screen using a collection of mapped P-element insertions that were previously shown to cause lethality and eye defects in Drosophila melanogaster. Of 280 mutants, 52 exhibited dendritic defects. Further database analyses, complementation tests, and RNA interference validations verified 40 P-element insertion genes as being responsible for the dendritic defects. Twenty-eight mutants presented severe arbor reduction, and the remainder displayed other abnormalities. The intrinsic regulators encoded by the identified genes participate in multiple conserved mechanisms and pathways, including the protein folding machinery and the chaperonin-containing TCP-1 (CCT) complex that facilitates tubulin folding. Mutant neurons in which expression of CCT4 or CCT5 was depleted exhibited severely retarded dendrite growth. We show that CCT localizes in dendrites and is required for dendritic microtubule organization and tubulin stability, suggesting that CCT-mediated tubulin folding occurs locally within dendrites. Our study also reveals novel mechanisms underlying dendrite morphogenesis. For example, we show that Drosophila Nogo signaling is required for dendrite development and that Mummy and Wech also regulate dendrite morphogenesis, potentially via Dpp- and integrin-independent pathways. Our methodology represents an efficient strategy for identifying intrinsic dendrite regulators, and provides insights into the plethora of molecular mechanisms underlying dendrite morphogenesis.
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Affiliation(s)
- Ying-Hsuan Wang
- Department of Biomedical Sciences, National Chung Cheng University, Chiayi, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Zhao-Ying Ding
- Department of Biomedical Sciences, National Chung Cheng University, Chiayi, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Min-Lang Huang
- Department of Biomedical Sciences, National Chung Cheng University, Chiayi, Taiwan
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7
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Abstract
Sensing environmental cues requires well-built neuronal circuits linked to the body surface. Sensory neurons generate dendrites to innervate surface epithelium, thereby making it the largest sensory organ in the body. Previous studies have illustrated that neuronal type, physiological function and branching patterns are determined by intrinsic factors. Perhaps for effective sensation or protection, sensory dendrites bind to or are surrounded by the substrate epidermis. Recent studies have shed light on the mechanisms by which dendrites interact with their substrates. These interactions suggest that substrates can regulate dendrite guidance, arborization and degeneration. In this review, we focus on recent studies of Drosophila and Caenorhabditis elegans that demonstrate how epidermal cells can regulate dendrites in several aspects.
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Affiliation(s)
- Wei-Kang Yang
- Institute of Molecular Biology, Academia Sinica , Taipei 115 , Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica , Taipei 115 , Taiwan
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8
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Chen PY, Tsai YW, Cheng YJ, Giangrande A, Chien CT. Glial response to hypoxia in mutants of NPAS1/3 homolog Trachealess through Wg signaling to modulate synaptic bouton organization. PLoS Genet 2019; 15:e1007980. [PMID: 31381576 PMCID: PMC6695205 DOI: 10.1371/journal.pgen.1007980] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 08/15/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022] Open
Abstract
Synaptic structure and activity are sensitive to environmental alterations. Modulation of synaptic morphology and function is often induced by signals from glia. However, the process by which glia mediate synaptic responses to environmental perturbations such as hypoxia remains unknown. Here, we report that, in the mutant for Trachealess (Trh), the Drosophila homolog for NPAS1 and NPAS3, smaller synaptic boutons form clusters named satellite boutons appear at larval neuromuscular junctions (NMJs), which is induced by the reduction of internal oxygen levels due to defective tracheal branches. Thus, the satellite bouton phenotype in the trh mutant is suppressed by hyperoxia, and recapitulated in wild-type larvae raised under hypoxia. We further show that hypoxia-inducible factor (HIF)-1α/Similar (Sima) is critical in mediating hypoxia-induced satellite bouton formation. Sima upregulates the level of the Wnt/Wingless (Wg) signal in glia, leading to reorganized microtubule structures within presynaptic sites. Finally, hypoxia-induced satellite boutons maintain normal synaptic transmission at the NMJs, which is crucial for coordinated larval locomotion.
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Affiliation(s)
- Pei-Yi Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yi-Wei Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- Centre National de la Recherche Scientifique, UMR7104, Illkirch, France
- Institut National de la Santé et de la Recherche Médicale, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Cheng-Ting Chien
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- * E-mail:
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9
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Yang WK, Chueh YR, Cheng YJ, Siegenthaler D, Pielage J, Chien CT. Epidermis-Derived L1CAM Homolog Neuroglian Mediates Dendrite Enclosure and Blocks Heteroneuronal Dendrite Bundling. Curr Biol 2019; 29:1445-1459.e3. [PMID: 31006568 DOI: 10.1016/j.cub.2019.03.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/31/2019] [Accepted: 03/23/2019] [Indexed: 12/31/2022]
Abstract
Building sensory dendritic arbors requires branching, growth, spacing, and substrate support. The conserved L1CAM family of cell-adhesion molecules generates neuronal isoforms to regulate neurite development in various aspects. However, whether non-neuronal isoforms participate in any of these aspects is unclear. In Drosophila, the L1CAM homolog Neuroglian (Nrg) is expressed as two isoforms: the neuronal isoform Nrg180 on dendritic surfaces of dendritic arborization (da) neurons and the non-neuronal isoform Nrg167 in epidermis innervated by dendrites. We found that epidermal Nrg167 encircles dendrites by interactions with dendritic Nrg180 to support dendrite growth, stabilization, and enclosure inside epidermis. Interestingly, whereas Nrg180 forms homophilic interactions to facilitate axonal bundling, heteroneuronal dendrites in the same innervating field avoid bundling through unknown mechanisms to maintain individual dendritic patterns. Here, we show that both epidermal Nrg167 depletion and neuronal Nrg180 overexpression can cause dendrite bundling, with genetic analyses suggesting that Nrg167-Nrg180 interactions antagonize Nrg180-Nrg180 homophilic interaction to prevent dendrite bundling. Furthermore, internalization of Nrg180 also participates in resolving dendrite bundling, as overexpression of endocytosis-defective Nrg180 and compromising endocytosis in neurons both exacerbated dendrite-bundling defects. Together, our study highlights the functional significance of substrate-derived Nrg167 in conferring dendrite stability, positioning, and avoidance.
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Affiliation(s)
- Wei-Kang Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ru Chueh
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Dominique Siegenthaler
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Pielage
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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10
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Abstract
Nithianandam and Chien show via in vivo imaging that a dynamic population of F-actin termed actin blobs propagates bidirectionally in dendrites and stalls at future branching sites. The F-actin–severing protein Tsr/cofilin is a regulator of actin blob dynamics and dendrite branching. The actin cytoskeleton provides structural stability and adaptability to the cell. Neuronal dendrites frequently undergo morphological changes by emanating, elongating, and withdrawing branches. However, the knowledge about actin dynamics in dendrites during these processes is limited. By performing in vivo imaging of F-actin markers, we found that F-actin was highly dynamic and heterogeneously distributed in dendritic shafts with enrichment at terminal dendrites. A dynamic F-actin population that we named actin blobs propagated bidirectionally at an average velocity of 1 µm/min. Interestingly, these actin blobs stalled at sites where new dendrites would branch out in minutes. Overstabilization of F-actin by the G15S mutant abolished actin blobs and dendrite branching. We identified the F-actin–severing protein Tsr/cofilin as a regulator of dynamic actin blobs and branching activity. Hence, actin blob localization at future branching sites represents a dendrite-branching mechanism to account for highly diversified dendritic morphology.
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Affiliation(s)
- Vanitha Nithianandam
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Cheng-Ting Chien
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan .,Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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11
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Liao CP, Li H, Lee HH, Chien CT, Pan CL. Cell-Autonomous Regulation of Dendrite Self-Avoidance by the Wnt Secretory Factor MIG-14/Wntless. Neuron 2018; 98:320-334.e6. [DOI: 10.1016/j.neuron.2018.03.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 02/06/2018] [Accepted: 03/16/2018] [Indexed: 11/26/2022]
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12
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Wang CH, Huang YC, Chen PY, Cheng YJ, Kao HH, Pi H, Chien CT. USP5/Leon deubiquitinase confines postsynaptic growth by maintaining ubiquitin homeostasis through Ubiquilin. eLife 2017; 6. [PMID: 28489002 PMCID: PMC5438252 DOI: 10.7554/elife.26886] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/09/2017] [Indexed: 12/14/2022] Open
Abstract
Synapse formation and growth are tightly controlled processes. How synaptic growth is terminated after reaching proper size remains unclear. Here, we show that Leon, the Drosophila USP5 deubiquitinase, controls postsynaptic growth. In leon mutants, postsynaptic specializations of neuromuscular junctions are dramatically expanded, including the subsynaptic reticulum, the postsynaptic density, and the glutamate receptor cluster. Expansion of these postsynaptic features is caused by a disruption of ubiquitin homeostasis with accumulation of free ubiquitin chains and ubiquitinated substrates in the leon mutant. Accumulation of Ubiquilin (Ubqn), the ubiquitin receptor whose human homolog ubiquilin 2 is associated with familial amyotrophic lateral sclerosis, also contributes to defects in postsynaptic growth and ubiquitin homeostasis. Importantly, accumulations of postsynaptic proteins cause different aspects of postsynaptic overgrowth in leon mutants. Thus, the deubiquitinase Leon maintains ubiquitin homeostasis and proper Ubqn levels, preventing postsynaptic proteins from accumulation to confine postsynaptic growth. DOI:http://dx.doi.org/10.7554/eLife.26886.001
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Affiliation(s)
- Chien-Hsiang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
| | - Yi-Chun Huang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Department of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Pei-Yi Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Hsiu-Hua Kao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Haiwei Pi
- Department of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.,Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan
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13
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Xi X, Lu L, Zhuge CC, Chen X, Zhai Y, Cheng J, Mao H, Yang CC, Tan BCM, Lee YN, Chien CT, Ho MS. The hypoparathyroidism-associated mutation in Drosophila Gcm compromises protein stability and glial cell formation. Sci Rep 2017; 7:39856. [PMID: 28051179 PMCID: PMC5209662 DOI: 10.1038/srep39856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 11/29/2016] [Indexed: 01/05/2023] Open
Abstract
Differentiated neurons and glia are acquired from immature precursors via transcriptional controls exerted by factors such as proteins in the family of Glial Cells Missing (Gcm). Mammalian Gcm proteins mediate neural stem cell induction, placenta and parathyroid development, whereas Drosophila Gcm proteins act as a key switch to determine neuronal and glial cell fates and regulate hemocyte development. The present study reports a hypoparathyroidism-associated mutation R59L that alters Drosophila Gcm (Gcm) protein stability, rendering it unstable, and hyperubiquitinated via the ubiquitin-proteasome system (UPS). GcmR59L interacts with the Slimb-based SCF complex and Protein Kinase C (PKC), which possibly plays a role in its phosphorylation, hence altering ubiquitination. Additionally, R59L causes reduced Gcm protein levels in a manner independent of the PEST domain signaling protein turnover. GcmR59L proteins bind DNA, functionally activate transcription, and induce glial cells, yet at a less efficient level. Finally, overexpression of either wild-type human Gcmb (hGcmb) or hGcmb carrying the conserved hypoparathyroidism mutation only slightly affects gliogenesis, indicating differential regulatory mechanisms in human and flies. Taken together, these findings demonstrate the significance of this disease-associated mutation in controlling Gcm protein stability via UPS, hence advance our understanding on how glial formation is regulated.
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Affiliation(s)
- Xiao Xi
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Lu Lu
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Chun-Chun Zhuge
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Xuebing Chen
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Yuanfen Zhai
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Jingjing Cheng
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Haian Mao
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
| | - Chang-Ching Yang
- Department of Biomedical Sciences and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan
| | - Bertrand Chin-Ming Tan
- Department of Biomedical Sciences and Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan
| | - Yi-Nan Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Margaret S Ho
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, No. 150 Jimo Road, Shanghai 200120, China.,Department of Anatomy and Neurobiology, 1239 Siping Road, Tongji University School of Medicine, Shanghai, 200092, China
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14
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Chen YC, Kuo HY, Bornschein U, Takahashi H, Chen SY, Lu KM, Yang HY, Chen GM, Lin JR, Lee YH, Chou YC, Cheng SJ, Chien CT, Enard W, Hevers W, Pääbo S, Graybiel AM, Liu FC. Foxp2 controls synaptic wiring of corticostriatal circuits and vocal communication by opposing Mef2c. Nat Neurosci 2016; 19:1513-1522. [PMID: 27595386 PMCID: PMC5083203 DOI: 10.1038/nn.4380] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/05/2016] [Indexed: 12/14/2022]
Abstract
Cortico-basal ganglia circuits are critical for speech and language and are implicated in autism spectrum disorder (ASD), in which language function can be severely affected. We demonstrate that in the striatum, the gene, Foxp2, negatively interacts with the synapse suppressor, Mef2C. We present causal evidence that Mef2C inhibition by Foxp2 in neonatal mouse striatum controls synaptogenesis of corticostriatal inputs and vocalization in neonates. Mef2C suppresses corticostriatal synapse formation and striatal spinogenesis, but can, itself, be repressed by Foxp2 through direct DNA binding. Foxp2 deletion de-represses Mef2C, and both intrastriatal and global decrease of Mef2C rescue vocalization and striatal spinogenesis defects of Foxp2-deletion mutants. These findings suggest that Foxp2-Mef2C signaling is critical to corticostriatal circuit formation. If found in humans, such signaling defects could contribute to a range of neurologic and neuropsychiatric disorders.
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Affiliation(s)
- Yi-Chuan Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Hsiao-Ying Kuo
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Ulrich Bornschein
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Hiroshi Takahashi
- Department of Neurology, National Hospital Organization, Tottori Medical Center, Tottori, Japan
| | - Shih-Yun Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Kuan-Ming Lu
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Hao-Yu Yang
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Gui-May Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Jing-Ruei Lin
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Hsin Lee
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Yun-Chia Chou
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
| | - Sin-Jhong Cheng
- Neuroscience Program in Academia Sincia, Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Cheng-Ting Chien
- Neuroscience Program in Academia Sincia, Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Wolfgang Enard
- Anthropology and Human Genomics, Department Biology II, Ludwig-Maximilians University, Munich, Germany
| | - Wulf Hevers
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Svante Pääbo
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Ann M Graybiel
- McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Fu-Chin Liu
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
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15
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Abstract
Studying the auditory system of the fruit fly can reveal how hearing works in mammals.
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Affiliation(s)
- Yi-Nan Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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16
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Lin CH, Lin HI, Chen ML, Lai TT, Cao LP, Farrer MJ, Wu RM, Chien CT. Lovastatin protects neurite degeneration inLRRK2-G2019Sparkinsonism through activating the Akt/Nrf pathway and inhibiting GSK3β activity. Hum Mol Genet 2016; 25:1965-1978. [DOI: 10.1093/hmg/ddw068] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/22/2016] [Indexed: 11/13/2022] Open
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17
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Abstract
Lrrk regulates Golgi outpost (GOP) dynamics in dendrites by antagonizing the interaction between the golgin Lva and dynein heavy chain at GOPs, thereby disrupting minus end–directed transport along dendritic microtubules by dynein. Constructing the dendritic arbor of neurons requires dynamic movements of Golgi outposts (GOPs), the prominent component in the dendritic secretory pathway. GOPs move toward dendritic ends (anterograde) or cell bodies (retrograde), whereas most of them remain stationary. Here, we show that Leucine-rich repeat kinase (Lrrk), the Drosophila melanogaster homologue of Parkinson’s disease–associated Lrrk2, regulates GOP dynamics in dendrites. Lrrk localized at stationary GOPs in dendrites and suppressed GOP movement. In Lrrk loss-of-function mutants, anterograde movement of GOPs was enhanced, whereas Lrrk overexpression increased the pool size of stationary GOPs. Lrrk interacted with the golgin Lava lamp and inhibited the interaction between Lva and dynein heavy chain, thus disrupting the recruitment of dynein to Golgi membranes. Whereas overexpression of kinase-dead Lrrk caused dominant-negative effects on GOP dynamics, overexpression of the human LRRK2 mutant G2019S with augmented kinase activity promoted retrograde movement. Our study reveals a pathogenic pathway for LRRK2 mutations causing dendrite degeneration.
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Affiliation(s)
- Chin-Hsien Lin
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Hsun Li
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang-Ming University and Academia Sinica, Taipei 115, Taiwan
| | - Yi-Nan Lee
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Ruey-Meei Wu
- Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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18
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Huang YC, Lu YN, Wu JT, Chien CT, Pi H. The COP9 signalosome converts temporal hormone signaling to spatial restriction on neural competence. PLoS Genet 2014; 10:e1004760. [PMID: 25393278 PMCID: PMC4230841 DOI: 10.1371/journal.pgen.1004760] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 09/16/2014] [Indexed: 12/23/2022] Open
Abstract
During development, neural competence is conferred and maintained by integrating spatial and temporal regulations. The Drosophila sensory bristles that detect mechanical and chemical stimulations are arranged in stereotypical positions. The anterior wing margin (AWM) is arrayed with neuron-innervated sensory bristles, while posterior wing margin (PWM) bristles are non-innervated. We found that the COP9 signalosome (CSN) suppresses the neural competence of non-innervated bristles at the PWM. In CSN mutants, PWM bristles are transformed into neuron-innervated, which is attributed to sustained expression of the neural-determining factor Senseless (Sens). The CSN suppresses Sens through repression of the ecdysone signaling target gene broad (br) that encodes the BR-Z1 transcription factor to activate sens expression. Strikingly, CSN suppression of BR-Z1 is initiated at the prepupa-to-pupa transition, leading to Sens downregulation, and termination of the neural competence of PWM bristles. The role of ecdysone signaling to repress br after the prepupa-to-pupa transition is distinct from its conventional role in activation, and requires CSN deneddylating activity and multiple cullins, the major substrates of deneddylation. Several CSN subunits physically associate with ecdysone receptors to represses br at the transcriptional level. We propose a model in which nuclear hormone receptors cooperate with the deneddylation machinery to temporally shutdown downstream target gene expression, conferring a spatial restriction on neural competence at the PWM. A critical step in building a functional nervous system is to generate neurons at the appropriate locations. Neural competence is acquired at the precursor stage with the expression of specific transcription factors. One such critical factor is Senseless (Sens), as precursors lacking Sens fail to develop to neurons. Here we describe the critical role of protein complex COP9 signalosome (CSN) that regulates Sens expression by integrating temporal and spatial information. This was studied in developing Drosophila wing tissues, in which the anterior wing margin develops neuron-innervated bristles, while the posterior wing margin develops non-innervated bristles. The CSN complex is required for the anterior-posterior difference in spatial patterning of neuron formation, and posterior cells lacking CSN develop innervated bristles like anterior cells. CSN accomplishes this by transforming the temporal hormonal ecdysone signaling from activation to repression of downstream target BR-Z1. As BR-Z1 itself is a transcription activator, repression of BR-Z1 in turn leads to repression of Sens in posterior wing margin, eventually terminating the neural competence. Repression of BR-Z1 expression requires the interaction between the CSN complex and the ecdysone receptors. Our results suggest a novel CSN-mediated regulation that converts temporal hormone signaling to the patterning of neurons at the right place.
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Affiliation(s)
- Yi-Chun Huang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Insitute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yu-Nung Lu
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - June-Tai Wu
- Institute of Molecular Biology, National Taiwan University, Taipei, Taiwan
| | - Cheng-Ting Chien
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Insitute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- * E-mail: (CTC); (HP)
| | - Haiwei Pi
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- * E-mail: (CTC); (HP)
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19
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Wang CH, Chen GC, Chien CT. The deubiquitinase Leon/USP5 regulates ubiquitin homeostasis during Drosophila development. Biochem Biophys Res Commun 2014; 452:369-75. [PMID: 25152394 DOI: 10.1016/j.bbrc.2014.08.069] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 08/14/2014] [Indexed: 01/09/2023]
Abstract
Ubiquitination and the reverse process deubiquitination regulate protein stability and function during animal development. The Drosophila USP5 homolog Leon functions as other family members of unconventional deubiquitinases, disassembling free, substrate-unconjugated polyubiquitin chains to replenish the pool of mono-ubiquitin, and maintaining cellular ubiquitin homeostasis. However, the significance of Leon/USP5 in animal development is still unexplored. In this study, we generated leon mutants to show that Leon is essential for animal viability and tissue integrity during development. Both free and substrate-conjugated polyubiquitin chains accumulate in leon mutants, suggesting that abnormal ubiquitin homeostasis caused tissue disorder and lethality in leon mutants. Further analysis of protein expression profiles in leon mutants shows that the levels of all proteasomal subunits were elevated. Also, proteasomal enzymatic activities were elevated in leon mutants. However, proteasomal degradation of ubiquitinated substrates was impaired. Thus, aberrant ubiquitin homeostasis in leon mutants disrupts normal proteasomal degradation, which is compensated by elevating the levels of proteasomal subunits and activities. Ultimately, the failure to fully compensate the dysfunctional proteasome in leon mutants leads to animal lethality and tissue disorder.
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Affiliation(s)
- Chien-Hsiang Wang
- Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan; Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Guang-Chao Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Cheng-Ting Chien
- Institute of Neuroscience, National Yang-Ming University, Taipei 112, Taiwan; Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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20
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Chen CK, Chen WY, Chien CT. The POU-domain protein Pdm3 regulates axonal targeting of R neurons in the Drosophila ellipsoid body. Dev Neurobiol 2012; 72:1422-32. [PMID: 22190420 DOI: 10.1002/dneu.22003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 11/29/2011] [Accepted: 12/01/2011] [Indexed: 11/06/2022]
Abstract
The ability of axons to project correctly to the target is essential for the formation of complex neural networks. The intrinsic regulation of this process is still unclear. Here, we show that POU domain motif 3 (Pdm3) is required in ring (R) neurons to control precise axon targeting to the Drosophila ellipsoid body (EB). Pdm3 is expressed in neurons of the central nervous system in larvae and adults and required for the normal development of the EB of the central complex in the adult brain. The normal EB structure is abolished in pdm3 mutants, and this phenotype is rescued by pdm3 expression in R neurons, suggesting that the defect in axonal targeting of R neurons is the major cause in EB malformation in pdm3 mutants. We show that cell fate determination, dendritic arborization, and initial axon projection of R neurons are normal while the axonal targeting to the EB is defective in pdm3 mutants.
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Affiliation(s)
- Chien-Kuo Chen
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
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21
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Abstract
Pseudouridine (Ψ) synthases function in the formation of Ψ, the most abundant of the modified RNA residues. All Ψ synthases in E. coli are classified into one of five families according to their sequences. Among them, members of the RluA Ψ synthase family catalyze certain Ψ formations in ribosomal RNA. RluA family members are required for ribosomal assembly and bacterial growth. None of the RluA in multicellular organisms has been studied. In the Drosophila peripheral nervous system, multiple dendritic (MD) neurons are recognized by their dendritic arbors. MD neurons can also be identified by using the enhancer trap line E7-2-36, which expresses the lacZ gene in MD neurons. Here, we show that the P-element of E7-2-36 inserts into the Drosophila RluA-1 gene. RluA-1 is homologous to E. coli RluA family members and is evolutionarily conserved in multicellular organisms. In situ hybridization and immunocytochemistry revealed that RluA-1 is expressed in MD neurons. We investigated the RluA-1 enhancer responsible for MD expression and found that the membrane-tethered green fluorescent protein driven by RluA-1-GAL4 was expressed in the dendritic arbors of MD neurons, confirming that RluA-1 is indeed expressed in MD neurons. Thus, the expression of RluA-1 is spatially controlled during development.
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Affiliation(s)
- Chung-Chi Wang
- Department of Life Science, National Chung-Cheng University, Taiwan
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22
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Abstract
Mutations in the gene encoding leucine-rich repeat kinase 2 (LRRK2) play a major role in the development of Parkinson's disease. The most frequently defined mutations of LRRK2 are located in the central catalytic region of the LRRK2 protein, suggesting that dysregulations of its enzymatic activities contribute to PD pathogenesis. Herein, we review recent progress in research concerning how LRRK2 mutations affect cellular pathways and lead to neuronal degeneration. We also summarize recent evidence revealing the endogenous function of LRRK2 protein within cells. These concepts can be used to further understand disease pathophysiology and serve as a platform to develop therapeutic strategies for the treatment of Parkinson's disease.
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Affiliation(s)
- Chin-Hsien Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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23
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Wu JT, Lin WH, Chen WY, Huang YC, Tang CY, Ho MS, Pi H, Chien CT. CSN-mediated deneddylation differentially modulates Ci(155) proteolysis to promote Hedgehog signalling responses. Nat Commun 2011; 2:182. [PMID: 21304511 PMCID: PMC3105314 DOI: 10.1038/ncomms1185] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 01/11/2011] [Indexed: 01/15/2023] Open
Abstract
The Hedgehog (Hh) morphogen directs distinct cell responses according to its distinct signalling levels. Hh signalling stabilizes transcription factor cubitus interruptus (Ci) by prohibiting SCFSlimb-dependent ubiquitylation and proteolysis of Ci. How graded Hh signalling confers differential SCFSlimb-mediated Ci proteolysis in responding cells remains unclear. Here, we show that in COP9 signalosome (CSN) mutants, in which deneddylation of SCFSlimb is inactivated, Ci is destabilized in low-to-intermediate Hh signalling cells. As a consequence, expression of the low-threshold Hh target gene dpp is disrupted, highlighting the critical role of CSN deneddylation on low-to-intermediate Hh signalling response. The status of Ci phosphorylation and the level of E1 ubiquitin-activating enzyme are tightly coupled to this CSN regulation. We propose that the affinity of substrate–E3 interaction, ligase activity and E1 activity are three major determinants for substrate ubiquitylation and thereby substrate degradation in vivo. Hedgehog signalling gradients are required for proper wing formation in Drosophila, and Hedgehog is known to regulate the cubitus interruptus transcription factor. Here, the authors show that the COP9 signalosome has a critical role in translating a Hedgehog gradient into a cubitus interruptus gradient.
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Affiliation(s)
- June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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24
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Ding ZY, Wang YH, Luo ZK, Lee HF, Hwang J, Chien CT, Huang ML. Glial cell adhesive molecule unzipped mediates axon guidance in Drosophila. Dev Dyn 2010; 240:122-34. [PMID: 21117153 DOI: 10.1002/dvdy.22508] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Axon guidance needs help from the glial cell system during embryogenesis. In the Drosophila embryonic central nervous system (CNS), longitudinal glia (LG) have been implicated in axon guidance but the mechanism remains unclear. We identified the protein encoded by the Drosophila gene unzipped (uzip) as a novel cell adhesion molecule (CAM). Uzip expressed in Drosophila S2 cells triggered cell aggregation through homophilic binding. In the embryonic CNS, Uzip was mainly produced by the LG but was also located at axons, which is consistent with the secretion of Uzip expressed in cultured cells. Although uzip mutants displayed no axonal defect, loss of uzip enhanced the axonal defects in the mutant of N-cadherin (CadN) and the Wnt gene family member wnt5. Overexpression of uzip could rescue the phenotype in the CadNuzip(D43) mutant. Thus, Uzip is a novel CAM from the LG regulating axon guidance.
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Affiliation(s)
- Zhao-Ying Ding
- Department of Life Science, National Chung-Cheng University, Chia-Yi, Taiwan
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25
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Lin HC, Wu JT, Tan BCM, Chien CT. Cul4 and DDB1 regulate Orc2 localization, BrdU incorporation and Dup stability during gene amplification in Drosophila follicle cells. J Cell Sci 2009; 122:2393-401. [PMID: 19531585 DOI: 10.1242/jcs.042861] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In higher eukaryotes, the pre-replication complex (pre-RC) component Cdt1 is the major regulator in licensing control for DNA replication. The Cul4-DDB1-based ubiquitin ligase mediates Cdt1 ubiquitylation for subsequent proteolysis. During the initiation of chorion gene amplification, Double-parked (Dup), the Drosophila ortholog of Cdt1, is restricted to chorion gene foci. We found that Dup accumulated in nuclei in Cul4 mutant follicle cells, and the accumulation was less prominent in DDB1 mutant cells. Loss of Cul4 or DDB1 activity in follicle cells also compromised chorion gene amplification and induced ectopic genomic DNA replication. The focal localization of Orc2, a subunit of the origin recognition complex, is frequently absent in Cul4 mutant follicle cells. Therefore, Cul4 and DDB1 have differential functions during chorion gene amplification.
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Affiliation(s)
- Hsiu-Chen Lin
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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26
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Peng YH, Yang WK, Lin WH, Lai TT, Chien CT. Nak regulates Dlg basal localization in Drosophila salivary gland cells. Biochem Biophys Res Commun 2009; 382:108-13. [PMID: 19258011 DOI: 10.1016/j.bbrc.2009.02.139] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Accepted: 02/25/2009] [Indexed: 01/10/2023]
Abstract
Protein trafficking is highly regulated in polarized cells. During development, how the trafficking of cell junctional proteins is regulated for cell specialization is largely unknown. In the maturation of Drosophila larval salivary glands (SGs), the Dlg protein is essential for septate junction formation. We show that Dlg was enriched in the apical membrane domain of proximal cells and localized basolaterally in distal mature cells. The transition of Dlg distribution was disrupted in nak mutants. Nak associated with the AP-2 subunit alpha-Ada and the AP-1 subunit AP-1gamma. In SG cells disrupting AP-1 and AP-2 activities, Dlg was enriched in the apical membrane. Therefore, Nak regulates the transition of Dlg distribution likely through endocytosis of Dlg from the apical membrane domain and transcytosis of Dlg to the basolateral membrane domain during the maturation of SGs development.
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Affiliation(s)
- Yu-Huei Peng
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan
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27
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Tsai PI, Kao HH, Grabbe C, Lee YT, Ghose A, Lai TT, Peng KP, Van Vactor D, Palmer RH, Chen RH, Yeh SR, Chien CT. Fak56 functions downstream of integrin alphaPS3betanu and suppresses MAPK activation in neuromuscular junction growth. Neural Dev 2008; 3:26. [PMID: 18925939 PMCID: PMC2576229 DOI: 10.1186/1749-8104-3-26] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 10/16/2008] [Indexed: 12/11/2022] Open
Abstract
Background Focal adhesion kinase (FAK) functions in cell migration and signaling through activation of the mitogen-activated protein kinase (MAPK) signaling cascade. Neuronal function of FAK has been suggested to control axonal branching; however, the underlying mechanism in this process is not clear. Results We have generated mutants for the Drosophila FAK gene, Fak56. Null Fak56 mutants display overgrowth of larval neuromuscular junctions (NMJs). Localization of phospho-FAK and rescue experiments suggest that Fak56 is required in presynapses to restrict NMJ growth. Genetic analyses imply that FAK mediates the signaling pathway of the integrin αPS3βν heterodimer and functions redundantly with Src. At NMJs, Fak56 downregulates ERK activity, as shown by diphospho-ERK accumulation in Fak56 mutants, and suppression of Fak56 mutant NMJ phenotypes by reducing ERK activity. Conclusion We conclude that Fak56 is required to restrict NMJ growth during NMJ development. Fak56 mediates an extracellular signal through the integrin receptor. Unlike its conventional role in activating MAPK/ERK, Fak56 suppresses ERK activation in this process. These results suggest that Fak56 mediates a specific neuronal signaling pathway distinct from that in other cellular processes.
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Affiliation(s)
- Pei-I Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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Abstract
The ubiquitin-like protein Nedd8/Rub1 covalently modifies and activates cullin ubiquitin ligases. However, the repertoire of Nedd8-modified proteins and the regulation of protein neddylation status are not clear. The cysteine protease DEN1/NEDP1 specifically processes the Nedd8 precursor and has been suggested to deconjugate Nedd8 from cullin proteins. By characterizing the Drosophila DEN1 protein and DEN1 null (DEN1(null)) mutants, we provide in vitro and in vivo evidence that DEN1, in addition to processing Nedd8, deneddylates many cellular proteins. Although purified DEN1 protein efficiently deneddylates the Nedd8-conjugated cullin proteins Cul1 and Cul3, neddylated Cul1 and Cul3 protein levels are not enhanced in DEN1(null). Strikingly, many cellular proteins are highly neddylated in DEN1 mutants and are deneddylated by purified DEN1 protein. DEN1 deneddylation activity is distinct from that of the cullin-deneddylating CSN. Genetic analyses indicate that a balance between neddylation and deneddylation maintained by DEN1 is crucial for animal viability.
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Affiliation(s)
- Yaru Chan
- Institute of Molecular Biology, Academia Sinica, 128 Sec No. 2 Academia Road, Taipei 115, Taiwan
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29
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Rencus-Lazar S, Amir Y, Wu J, Chien CT, Chamovitz DA, Segal D. The proto-oncogene Int6 is essential for neddylation of Cul1 and Cul3 in Drosophila. PLoS One 2008; 3:e2239. [PMID: 18493598 PMCID: PMC2375110 DOI: 10.1371/journal.pone.0002239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Accepted: 04/04/2008] [Indexed: 11/24/2022] Open
Abstract
Int6 is a proto-oncogene implicated in various types of cancer, but the mechanisms underlying its activity are not clear. Int6 encodes a subunit of the eukaryotic translation initiation factor 3, and interacts with two related complexes, the proteasome, whose activity is regulated by Int6 in S. pombe, and the COP9 signalosome. The COP9 signalosome regulates the activity of Cullin-Ring Ubiquitin Ligases via deneddylation of their cullin subunit. We report here the generation and analysis of two Drosophila mutants in Int6. The mutants are lethal demonstrating that Int6 is an essential gene. The mutant larvae accumulate high levels of non-neddylated Cul1, suggesting that Int6 is a positive regulator of cullin neddylation. Overexpression in Int6 in cell culture leads to accumulation of neddylated cullins, further supporting a positive role for Int6 in regulating neddylation. Thus Int6 and the COP9 signalosome play opposing roles in regulation of cullin neddylation.
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Affiliation(s)
- Sigal Rencus-Lazar
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Yaniv Amir
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Junetai Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Daniel A. Chamovitz
- Department of Plant Sciences, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (DC); (DS)
| | - Daniel Segal
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (DC); (DS)
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Lo CW, Huang HP, Lin HM, Chien CT, Wang CJ. Effect ofHibiscus anthocyanins-rich extract induces apoptosis of proliferating smooth muscle cell via activation of P38 MAPK and p53 pathway. Mol Nutr Food Res 2007; 51:1452-60. [DOI: 10.1002/mnfr.200700151] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Ou CY, Wang CH, Jiang J, Chien CT. Suppression of Hedgehog signaling by Cul3 ligases in proliferation control of retinal precursors. Dev Biol 2007; 308:106-19. [PMID: 17559828 DOI: 10.1016/j.ydbio.2007.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 05/08/2007] [Accepted: 05/10/2007] [Indexed: 02/04/2023]
Abstract
Cullin-RING ubiquitin ligases ubiquitinate protein substrates and control their levels through degradation. Here we show that cullin3 (Cul3) suppresses Hedgehog (Hh) signaling through downregulating the level of the signaling pathway effector cubitus interruptus (Ci). High-level Hh signaling promotes Cul3-dependent Ci degradation, leading to the downregulation of Hh signaling. This process is manifested in controlling cell proliferation during Drosophila retinal development. In Cul3 mutants, the population of interommatidial cells is increased, which can be mimicked by overexpression of Ci and suppressed by depleting endogenous Ci. Hh also regulates the population of interommatidial cells in the pupal stage. Alterations in the interommatidial cell population correlate with alterations in precursor proliferation in the second mitotic wave of larval eye discs. Taken together, these results suggest that Cul3 downregulates Ci levels to modulate Hh signaling activity, thus ensuring proper cell proliferation during retinal development.
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Affiliation(s)
- Chan-Yen Ou
- Taiwan International Graduate Program, Graduate Institute of Life Science, National Defense Medical Center and Academia Sinica, Taipei, Taiwan
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32
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Abstract
A key issue in development is how to specify single isolated precursor cells to adopt a distinct fate from a group of naive cells. Studies on the development of Drosophila external sensory (ES) organs have revealed multiple mechanisms to specify single sensory organ precursors (SOPs) from clusters of cells with equivalent neural potential. Initially single SOPs are selected in part through cell-cell competition from clusters of ectodermal cells that express proneural proteins. To reinforce the singularity, lateral inhibition through the Delta/Notch system and feedback regulations lead to exclusive expression of proneural proteins in SOPs. As transcriptional activators, proneural proteins execute a genetic program in SOP cells for the development of an eventually ES organ. In this article, we will summarize recent advances on how transcriptional regulation, protein degradation, endocytosis and gene silencing by microRNA participate in SOP specification.
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Affiliation(s)
- Haiwei Pi
- Department of Life Science, Chang-Gung University, 259 Wen-Hwa 1st Road, Kweishan, Tao-Yuan, 333, Taiwan
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33
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Tan BCM, Chien CT, Hirose S, Lee SC. Functional cooperation between FACT and MCM helicase facilitates initiation of chromatin DNA replication. EMBO J 2006; 25:3975-85. [PMID: 16902406 PMCID: PMC1560368 DOI: 10.1038/sj.emboj.7601271] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 07/18/2006] [Indexed: 01/21/2023] Open
Abstract
Chromatin is suppressive in nature to cellular enzymes that metabolize DNA, mainly due to the inherent inaccessibility of the DNA template. Despite extensive understanding of the involvement of chromatin-modifying factors in transcription, roles of related activities in DNA replication remain largely elusive. Here, we show that the heterodimeric transcriptional elongation factor FACT (facilitates chromatin transcription) is functionally linked to DNA synthesis. Its involvement in DNA replication is partly mediated by the stable association with the replicative helicase complex, MCM, and further by the coexistence with MCM on replication origin. Furthermore, relying on its nucleosome-reorganizing activity, FACT can facilitate chromatin unwinding by the MCM complex, which is otherwise inert on the nucleosomal template. As a consequence, the physical and functional interaction between FACT and MCM is an important determinant in the proper initiation of DNA replication and S phase in vivo. Together, our findings identify FACT as an integral and conserved component of the endogenous replication machinery, and support a model in which the concerted action of helicase and chromatin-modifying activities promotes chromosome replication.
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Affiliation(s)
| | | | - Susumu Hirose
- Department of Developmental Genetics, National Institute of Genetics, Mishima, Shizuokaken, Japan
| | - Sheng-Chung Lee
- Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Institute of Molecular Medicine, National Taiwan University, 7 Chung Shan South Road, Taipei, Taiwan. Tel.: +886 2 2356 2982; Fax: +886 2 2395 7801; E-mail:
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34
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Zhang Q, Zhang L, Wang B, Ou CY, Chien CT, Jiang J. A hedgehog-induced BTB protein modulates hedgehog signaling by degrading Ci/Gli transcription factor. Dev Cell 2006; 10:719-29. [PMID: 16740475 DOI: 10.1016/j.devcel.2006.05.004] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 05/15/2006] [Accepted: 05/16/2006] [Indexed: 12/20/2022]
Abstract
The Ci/Gli family of transcription factors mediates Hedgehog (Hh) signaling in many key developmental processes. Here we identify a Hh-induced MATH and BTB domain containing protein (HIB) as a negative regulator of the Hh pathway. Overexpressing HIB down regulates Ci and blocks Hh signaling, whereas inactivating HIB results in Ci accumulation and enhanced pathway activity. HIB binds the N- and C-terminal regions of Ci, both of which mediate Ci degradation. HIB forms a complex with Cul3, a scaffold for modular ubiquitin ligases, and promotes Ci ubiquitination and degradation through Cul3. Furthermore, HIB-mediated Ci degradation is stimulated by Hh and inhibited by Suppressor of Fused (Sufu). The mammalian homolog of HIB, SPOP, can functionally substitute for HIB, and Gli proteins are degraded by HIB/SPOP in Drosophila. We provide evidence that HIB prevents aberrant Hh signaling posterior to the morphogenic furrow, which is essential for normal eye development.
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Affiliation(s)
- Qing Zhang
- Center for Developmental Biology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA
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35
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Abstract
Neddylation, a process that conjugates the ubiquitin-like polypeptide NEDD8 to cullin proteins, activates cullin-RING ubiquitin ligases (CRLs). Deneddylation, in which the COP9 signalosome (CSN) removes NEDD8 from cullins, inactivates CRLs. However, genetic studies of CSN function conclude that deneddylation also promotes CRL activity. It has been proposed that a cyclic transition through neddylation and deneddylation is required for the regulation of CRL activity in vivo. Recent discoveries suggest that an additional level of complexity exists, whereby CRL components are targets for degradation, mediated either by autocatalytic ubiquitination or by unknown mechanisms. Deneddylation by CSN and deubiquitylation by CSN-associated ubiquitin-specific protease 12 protect CRL components from cellular depletion, thus maintaining the physiological CRL activities.
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Affiliation(s)
- June-Tai Wu
- Institute of Molecular Biology, Academia Sinica, 115 Taipei, Taiwan
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36
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Abstract
The eukaryotic protein degradation pathway involves the ubiquitin (Ub) modification of substrates targeted for degradation by the 26S proteasome. The addition of Ub, a process called ubiquitination, is mediated by enzymes including the E3 Ub ligases which transfer the Ub to targeted substrates. A major type of E3 Ub ligases, the SCF (Skp-Cullin-F-box) complex, is composed of four major components: Skp1, Cul1/Cdc53, Roc1/Rbx1/Hrt1, and an F-box protein. The F-box component of the SCF machineries is responsible for recognizing different substrates for ubiquitination. Interaction with components of the SCF complex is mediated through the F-box motif of the F-box protein while it associates with phosphorylated substrates through its second protein-protein interaction motif such as Trp-Asp (WD) repeats or leucine-rich repeats (LRRs). By targeting diverse substrates, F-box proteins exert controls over stability of proteins and regulate the mechanisms for a wide-range of cellular processes. Here we discuss the importance of F-box proteins by providing a general overview and examples of how F-box proteins function in various cellular settings such as tissue development, cell proliferation, and cell death, in the modeling organism Drosophila.
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Affiliation(s)
- Margaret S Ho
- Institute of Molecular Biology, Academia Sinica, 115, Taipei, Taiwan
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37
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Wu JT, Lin HC, Hu YC, Chien CT. Neddylation and deneddylation regulate Cul1 and Cul3 protein accumulation. Nat Cell Biol 2005; 7:1014-20. [PMID: 16127432 DOI: 10.1038/ncb1301] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 08/12/2005] [Indexed: 12/25/2022]
Abstract
Cullin family proteins organize ubiquitin ligase (E3) complexes to target numerous cellular proteins for proteasomal degradation. Neddylation, the process that conjugates the ubiquitin-like polypeptide Nedd8 to the conserved lysines of cullins, is essential for in vivo cullin-organized E3 activities. Deneddylation, which removes the Nedd8 moiety, requires the isopeptidase activity of the COP9 signalosome (CSN). Here we show that in cells deficient for CSN activity, cullin1 (Cul1) and cullin3 (Cul3) proteins are unstable, and that to preserve their normal cellular levels, CSN isopeptidase activity is required. We further show that neddylated Cul1 and Cul3 are unstable - as suggested by the evidence that Nedd8 promotes the instability of both cullins - and that the unneddylatable forms of cullins are stable. The protein stability of Nedd8 is also subject to CSN regulation and this regulation depends on its cullin-conjugating ability, suggesting that Nedd8-conjugated cullins are degraded en bloc. We propose that while Nedd8 promotes cullin activation through neddylation, neddylation also renders cullins unstable. Thus, CSN deneddylation recycles the unstable, neddylated cullins into stable, unneddylated ones, and promotes cullin-organized E3 activity in vivo.
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Affiliation(s)
- June-Tai Wu
- Institute of Molecular Biology, Academia Sinica, 115, Taipei, Taiwan
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38
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Pi H, Huang SK, Tang CY, Sun YH, Chien CT. phyllopod is a target gene of proneural proteins in Drosophila external sensory organ development. Proc Natl Acad Sci U S A 2004; 101:8378-83. [PMID: 15148389 PMCID: PMC420402 DOI: 10.1073/pnas.0306010101] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proneural basic helix-loop-helix (bHLH) proteins initiate neurogenesis in both vertebrates and invertebrates. The Drosophila Achaete (Ac) and Scute (Sc) proteins are among the first identified members of the large bHLH proneural protein family. phyllopod (phyl), encoding an ubiquitin ligase adaptor, is required for ac- and sc-dependent external sensory (ES) organ development. Expression of phyl is directly activated by Ac and Sc. Forced expression of phyl rescues ES organ formation in ac and sc double mutants. phyl and senseless, encoding a Zn-finger transcriptional factor, depend on each other in ES organ development. Our results provide the first example that bHLH proneural proteins promote neurogenesis through regulation of protein degradation.
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Affiliation(s)
- Haiwei Pi
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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39
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Cheng YJ, Chien CT, Chen CF. Oxidative stress in bilateral total knee replacement, under ischaemic tourniquet. J Bone Joint Surg Br 2003; 85:679-82. [PMID: 12892190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Free radicals, such as reactive oxygen species (ROS) which are released abruptly after deflation of an ischaemic tourniquet, cause reperfusion injuries. Ischaemic precondition (IPC), however, can reduce the injury. In clinical practice, the sequential application and release of tourniquets is often used in bilateral total knee replacement (TKR) to obtain a clearer operative field, but the effects on the production of free radicals and lipid peroxidation have not been studied. In this study, we have observed the production of free radicals and the subsequent lipid peroxidation in bilateral TKR with sequential application of a tourniquet to examine the effect of IPC. Patients undergoing elective TKR under intrathecal anaesthesia were studied. Blood samples were obtained after spinal anaesthesia, one minute before and five and 20 minutes after release of each tourniquet. We used the lucigenin chemiluminescence analysis and the phosphatidylcholine hydroperoxide (PCOOH) assay to measure the production of ROS and lipid peroxidation. Our results showed that production of ROS significantly increased at five and 20 minutes after release of the first tourniquet and at five minutes after release of the second tourniquet, but returned to normal at 20 minutes after the second reperfusion. The peak production of ROS was at 20 minutes after the first reperfusion; lipid peroxidation did not change significantly. We conclude that in spite of significant production of ROS after the release of tourniquet, the IPC phenomenon occurs during bilateral TKR with sequential application of a tourniquet.
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Affiliation(s)
- Y J Cheng
- Department of Anaesthetics, College of Medicine, National Taiwan University, Taipei, Republic of China
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40
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Affiliation(s)
- Chan-Yen Ou
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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41
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Abstract
Establishment of planar polarity in the Drosophila compound eye requires precise 90 degrees rotation of the ommatidial clusters during development. We found that the morphogenetic furrow controls the stop of ommatidial rotation at 90 degrees by emitting signals to posterior ommatidial clusters. One such signal, Scabrous, is synthesized in the furrow cells and transported in vesicles to ommatidial row 6-8. Scabrous vesicles are transported through actin-based cellular extensions but not transcytosis. Scabrous functions nonautonomously to control the stop of ommatidial rotation by suppressing nemo activity in the second 45 degrees rotation. We propose that the morphogenetic furrow regulates precise ommatidial rotation by transporting Scabrous and perhaps other factors through actin-based cellular extensions.
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Affiliation(s)
- Ya-Hui Chou
- Graduate Institute of Life Sciences, National Defense Medical Center and Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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42
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Ou CY, Lin YF, Chen YJ, Chien CT. Distinct protein degradation mechanisms mediated by Cul1 and Cul3 controlling Ci stability in Drosophila eye development. Genes Dev 2002; 16:2403-14. [PMID: 12231629 PMCID: PMC187440 DOI: 10.1101/gad.1011402] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The ubiquitin-like protein, Nedd8, covalently modifies members of the Cullin family. Cullins are the major components of a series of ubiquitin ligases that control the degradation of a broad range of proteins. We found that Nedd8 modifies Cul1 in Drosophila. In Drosophila Nedd8 and Cul1 mutants, protein levels of the signal transduction effectors, Cubitus interruptus (Ci) and Armadillo (Arm), and the cell cycle regulator, Cyclin E (CycE), are highly accumulated, suggesting that the Cul1-based SCF complex requires Nedd8 modification for the degradation processes of Ci, Arm, and CycE in vivo. We further show that two distinct degradation mechanisms modulating Ci stability in the developing eye disc are separated by the morphogenetic furrow (MF) in which retinal differentiation is initiated. In cells anterior to the MF, Ci proteolytic processing promoted by PKA requires the activity of the Nedd8-modified Cul1-based SCF(Slimb) complex. In posterior cells, Ci degradation is controlled by a mechanism that requires the activity of Cul3, another member of the Cullin family. This posterior Ci degradation mechanism, which partially requires Nedd8 modification, is activated by Hedgehog (Hh) signaling and is PKA-independent.
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Affiliation(s)
- Chan-Yen Ou
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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43
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Abstract
Drosophila 14-3-3ε and 14-3-3ζ proteins have been shown to function in RAS/MAP kinase pathways that influence the differentiation of the adult eye and the embryo. Because 14-3-3 proteins have a conserved involvement in cell cycle checkpoints in other systems, we asked (1) whether Drosophila 14-3-3 proteins also function in cell cycle regulation, and (2) whether cell proliferation during Drosophila development has different requirements for the two 14-3-3 proteins. We find that antibody staining for 14-3-3 family members is cytoplasmic in interphase and perichromosomal in mitosis. Using mutants of cyclins, Cdk1 and Cdc25string to manipulate Cdk1 activity, we found that the localization of 14-3-3 proteins is coupled to Cdk1 activity and cell cycle stage. Relocalization of 14-3-3 proteins with cell cycle progression suggested cell-cycle-specific roles. This notion is confirmed by the phenotypes of 14-3-3ε and 14-3-3ζ mutants: 14-3-3ε is required to time mitosis in undisturbed post-blastoderm cell cycles and to delay mitosis following irradiation; 14-3-3ζ is required for normal chromosome separation during syncytial mitoses. We suggest a model in which 14-3-3 proteins act in the undisturbed cell cycle to set a threshold for entry into mitosis by suppressing Cdk1 activity, to block mitosis following radiation damage and to facilitate proper exit from mitosis.
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Affiliation(s)
- T T Su
- MCD Biology, University of Colorado, Boulder, CO 80309, USA.
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44
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Pi H, Wu HJ, Chien CT. A dual function ofphyllopodinDrosophilaexternal sensory organ development: cell fate specification of sensory organ precursor and its progeny. Development 2001; 128:2699-710. [PMID: 11526076 DOI: 10.1242/dev.128.14.2699] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During Drosophila external sensory organ development, one sensory organ precursor (SOP) arises from a proneural cluster, and undergoes asymmetrical cell divisions to produce an external sensory (es) organ made up of different types of daughter cells. We show that phyllopod (phyl), previously identified to be essential for R7 photoreceptor differentiation, is required in two stages of es organ development: the formation of SOP cells and cell fate specification of SOP progeny. Loss-of-function mutations in phyl result in failure of SOP formation, which leads to missing bristles in adult flies. At a later stage of es organ development, phyl mutations cause the first cell division of the SOP lineage to generate two identical daughters, leading to the fate transformation of neurons and sheath cells to hair cells and socket cells. Conversely, misexpression of phyl promotes ectopic SOP formation, and causes opposite fate transformation in SOP daughter cells. Thus, phyl functions as a genetic switch in specifying the fate of the SOP cells and their progeny. We further show that seven in absentia (sina), another gene required for R7 cell fate differentiation, is also involved in es organ development. Genetic interactions among phyl, sina and tramtrack (ttk) suggest that phyl and sina function in bristle development by antagonizing ttk activity, and ttk acts downstream of phyl. It has been shown previously that Notch (N) mutations induce formation of supernumerary SOP cells, and transformation from hair and socket cells to neurons. We further demonstrate that phyl acts epistatically to N. phyl is expressed specifically in SOP cells and other neural precursors, and its mRNA level is negatively regulated by N signaling. Thus, these analyses demonstrate that phyl acts downstream of N signaling in controlling cell fates in es organ development.
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Affiliation(s)
- H Pi
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529
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45
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Abstract
Glucocorticoid-induced apoptosis is a well-recognized physiological regulator of T-cell number and function. Alisol B acetate, a triterpene from Alisma Plantago-aquatica, has a glucocorticoid-like structure, and may have a similar function like glucocorticoid-induced apoptosis in both vascular smooth muscle cell line (A7r5) and human acute lymphoblastic leukemia cell line (CEM cells). For exploring its mechanism, mitochondria membrane potential and apoptosis-related gene expression were discussed. Alisol B (10(-6)-10(-4) M) inhibited serum-stimulated DNA synthesis in a concentration-dependent manner (IC50) = 4.0 +/- 0.8 x 10(-6) M in A7r5 and 2.1 +/- 1.2 x 10(-6) M in CEM cells). The cell viability was reduced at 10(-4) M of alisol B. Similar results were seen in dexamethasone treatment (a synthetic glucocorticoid, 10(-6) M, 48 h). Apoptosis was induced after the cells were exposed to 10(-5)-10(-4) M alisol B or 10(-6) M dexamethasone for 48 h. The mitochondrial membrane potential (delta psi(m)) was significantly reduced after the alisol B treatment, indicating that the mitochondria might play a role in the alisol B induced cell apoptosis. Alisol B (10(-5)-10(-4) M) increased the levels of c-myc and bax mRNA and proteins, but not on the anti-apoptotic proto-oncogene, bcl-2, in A7r5 and CEM cells. In contrast, dexamethasone (10(-6) M) treatment only caused significant increase in c-myc mRNA levels. These results suggest that the increased ratio of Bax/Bcl-2 and the decreased mitochondrial membrane potential might be involved in the mechanisms of alisol B-induced cell apoptosis.
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Affiliation(s)
- H W Chen
- Office for Medical Research, National Taiwan University Hospital, Taipei
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46
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Abstract
The early renal response to unilateral ureteral occlusion (UUO) and its mechanism have been extensively studied in dogs but seldom discussed in the most frequently used laboratory animals, rats. The acute phase of the renal response to UUO was studied in female rats weighing 190-236 g. We recorded the ureteral pressure and changes in renal parameters throughout 120 minutes of UUO in control (US, UUO + saline, n = 10), L-arginine-treated (UA, n = 10), and right-nephrectomized rats (UO, UUO in one kidney, n = 9). Ureteral pressure increased in all three groups of rats after complete ureteral obstruction. The extent of the increase was not significantly different between US and UA rats but was significantly higher in the UO rats. In US rats, the cortical microvascular blood flow (CMVBF), measured by a laser Doppler flowmeter, declined significantly, from 321 +/- 10 perfusion units (PU) to 260 +/- 11 PU. The percentage of drop in CMVBF at 120 minutes of UUO was significantly greater in UO (25.7 +/- 3.8 %) than in US (19 +/- 2.1%) and in UA (14 +/- 2%) rats. Acute UUO reduced the glomerular filtration rate (GFR) in US and UO rats, whereas L-arginine attenuated this decrease. The excretion of nitrate/nitrite was increased after UUO. Giving N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME, 12 mg/kg/h) during UUO did not reduce CMVBF more severely. Western blot analysis of endothelial nitric oxide synthase expression in the renal cortex and medulla protein extracts revealed no differences between US and sham-operated rats. Acute UUO did not lead to renal hyperemia in rats. Reduction of nitric oxide during UUO might contribute to the decrease of renal circulation during UUO.
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Affiliation(s)
- C F Chen
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
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47
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Cheng YP, Chien CT, Chen HW, Lin TP. Allozyme variation of Cyclobalanopsis championii (Fagaceae), a narrowly distributed species in southern Taiwan. J Hered 2001; 92:65-70. [PMID: 11336231 DOI: 10.1093/jhered/92.1.65] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Allozyme genetic variability in five natural populations of Cyclobalanopsis championii (Fagaceae) in Taiwan was investigated using 12 loci from 9 enzyme systems. The average values of parameters describing within-population variation, expected heterozygosity (He = 0.151), the percentage of polymorphic loci per individual (P = 50%), the average number of alleles per locus (A = 1.7), effective number of alleles per locus (Ae = 1.25), and the average number of alleles per polymorphic loci (AP = 2.2) are comparable to those of other long-lived woody plants. The overall fixation index (Fis = 0.208) indicates a significant deficiency of heterozygotes at the population level. Allelic frequency deviation from Hardy-Weinberg equilibrium was found for different loci in different populations. An exact test for population differentiation using the Tools for Population Genetic Analyses program also indicates that allelic frequencies among populations are significantly different (P < .001). Among-population variation, Gst, accounted for 9.2% of the total heterozygosity. The population at Shouchia and the southernmost population Nanjenshan had higher inbreeding coefficients (0.177 and 0.153, respectively) than did the northern populations. Genetic drift is supported by the observations of the variance components of linkage disequilibrium and a large proportion of loci in Nanjenshan and Shouchia that show pairwise locus disequilibrium. We believe continuous genetic drift in the southern populations will increase genetic divergence among populations of C. championii in Taiwan. Significant correlation was found between elevation and expected heterozygosity. We therefore inferred that temperature is the most important ecological factor to influence the genetic diversity of C. championii.
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Affiliation(s)
- Y P Cheng
- Taiwan Forestry Research Institute, Taipei
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48
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Affiliation(s)
- C T Chien
- Department of Clinical Research, National Taiwan University Hospital, Taipei, Taiwan, People's Republic of China
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49
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Chien CT, Hsu SM, Chen CF, Lee PH, Lai MK. Prolonged ischemia potentiates apoptosis formation during reperfusion by increase of caspase 3 activity and free radical generation. Transplant Proc 2000; 32:2065-6. [PMID: 11120068 DOI: 10.1016/s0041-1345(00)01560-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- C T Chien
- Department of Clinical Research, National Taiwan University Hospital, Taipei, People's Republic of China
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50
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Chien CT, Yu HJ, Cheng YJ, Wu MS, Chen CF, Hsu SM. Reduction in renal haemodynamics by exaggerated vesicovascular reflex in rats with acute urinary retention. J Physiol 2000; 526 Pt 2:397-408. [PMID: 10896728 PMCID: PMC2270022 DOI: 10.1111/j.1469-7793.2000.t01-1-00397.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. We examined the possibility that a vesicovascular reflex is exaggerated by acute urinary retention, and that the increase in renal vascular resistance caused by this reflex may lead to renal dysfunction. We evaluated the vesicovascular responses to normal micturition (NM, transcystometric condition) and acute urinary retention (isovolumetric condition mimicking complete bladder-outlet obstruction (CBOO) and partial urethral ligation mimicking partial bladder-outlet obstruction (PBOO)) in anaesthetized female Wistar rats. 2. Acute urinary retention due to CBOO or PBOO provoked a prolonged or increased intravesical pressure, an enhancement in both bladder pelvic afferent and bladder pelvic efferent nervous activity, and an elevation in mean arterial blood pressure. 3. Single-unit analysis showed that these vesicovascular reflexes were triggered by activation of low-threshold and high-threshold bladder mechanoreceptors, but not by renal uretropelvic mechanoreceptors. 4. Bladder contraction in CBOO and PBOO conditions and graded increases in bladder volume significantly reduced renal blood flow and cortical microvascular blood flow. The acute urinary retention-induced renal vasoconstriction was mediated by the renal nerve. Renal denervation, but not bilateral ureteral resection, abolished the renal vasoconstriction associated with the vesicovascular reflexes. 5. These findings indicate that exaggerated activation of bladder afferents exerts a positive feedback effect to increase sympathetic outflow to the kidney further, thereby contributing to significant renal vasoconstriction via a renal nerve-dependent mechanism.
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Affiliation(s)
- C T Chien
- Office for Clinical Research, National Taiwan University Hospital, Taipei, Taiwan
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