1
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Baccino-Calace M, Schmidt K, Müller M. The E3 ligase Thin controls homeostatic plasticity through neurotransmitter release repression. eLife 2022; 11:71437. [PMID: 35796533 PMCID: PMC9299833 DOI: 10.7554/elife.71437] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 07/06/2022] [Indexed: 11/13/2022] Open
Abstract
Synaptic proteins and synaptic transmission are under homeostatic control, but the relationship between these two processes remains enigmatic. Here, we systematically investigated the role of E3 ubiquitin ligases, key regulators of protein degradation-mediated proteostasis, in presynaptic homeostatic plasticity (PHP). An electrophysiology-based genetic screen of 157 E3 ligase-encoding genes at the Drosophila neuromuscular junction identified thin, an ortholog of human tripartite motif-containing 32 (TRIM32), a gene implicated in several neurological disorders, including autism spectrum disorder and schizophrenia. We demonstrate that thin functions presynaptically during rapid and sustained PHP. Presynaptic thin negatively regulates neurotransmitter release under baseline conditions by limiting the number of release-ready vesicles, largely independent of gross morphological defects. We provide genetic evidence that thin controls release through dysbindin, a schizophrenia-susceptibility gene required for PHP. Thin and Dysbindin localize in proximity within presynaptic boutons, and Thin degrades Dysbindin in vitro. Thus, the E3 ligase Thin links protein degradation-dependent proteostasis of Dysbindin to homeostatic regulation of neurotransmitter release.
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Affiliation(s)
| | - Katharina Schmidt
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Martin Müller
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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2
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Ukita Y, Okumura M, Chihara T. Ubiquitin proteasome system in circadian rhythm and sleep homeostasis: Lessons from Drosophila. Genes Cells 2022; 27:381-391. [PMID: 35438236 PMCID: PMC9322287 DOI: 10.1111/gtc.12935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 11/30/2022]
Abstract
Sleep is regulated by two main processes: the circadian clock and sleep homeostasis. Circadian rhythms have been well studied at the molecular level. In the Drosophila circadian clock neurons, the core clock proteins are precisely regulated by post-translational modifications and degraded via the ubiquitin-proteasome system (UPS). Sleep homeostasis, however, is less understood; nevertheless, recent reports suggest that proteasome-mediated degradation of core clock proteins or synaptic proteins contributes to the regulation of sleep amount. Here, we review the molecular mechanism of the UPS and summarize the role of protein degradation in the regulation of circadian clock and homeostatic sleep in Drosophila. Moreover, we discuss the potential interaction between circadian clock and homeostatic sleep regulation with a prime focus on E3 ubiquitin ligases.
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Affiliation(s)
- Yumiko Ukita
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Misako Okumura
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Takahiro Chihara
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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3
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Mast E, Bieser KL, Abraham-Villa M, Adams V, Akinlehin AJ, Aquino LZ, Austin JL, Austin AK, Beckham CN, Bengson EJ, Bieszk A, Bogard BL, Brennan RC, Brnot RM, Cirone NJ, Clark MR, Cooper BN, Cruz D, Daprizio KA, DeBoe J, Dencker MM, Donnelly LL, Driscoll L, DuBeau RJ, Durso SW, Ejub A, Elgosbi W, Estrada M, Evins K, Fox PD, France JM, Franco Hernandez MG, Garcia LA, Garl O, Gorsuch MR, Gorzeman-mohr MA, Grothouse ME, Gubbels ME, Hakemiamjad R, Harvey CV, Hoeppner MA, Ivanov JL, Johnson VM, Johnson JL, Johnson A, Johnston K, Keller KR, Kennedy BT, Killian LR, Klumb M, Koehn OL, Koym AS, Kress KJ, Landis RE, Lewis KN, Lim E, Lopez IK, Lowe D, Luengo Carretero P, Lunaburg G, Mallinder SL, Marshall NA, Mathew J, Mathew J, Mcmanaway HS, Meegan EN, Meyst JD, Miller MJ, Minogue CK, Mohr AA, Moran CI, Moran A, Morris MD, Morrison MD, Moses EA, Mullins CJ, Neri CI, Nichols JM, Nickels BR, Okai AM, Okonmah C, Paramo M, Paramo M, Parker SL, Parmar NK, Paschal J, Patel P, Patel D, Perkins EB, Perry MM, Perry Z, Pollock AA, Portalatin O, Proffitt KS, Queen JT, Quemeneur AC, Richardson AG, Rosenberger K, Rutherford AM, Santos-Perez IX, Sarti CY, Schouweiler LJ, Sessing LM, Setaro SO, Silvestri CF, Smith OA, Smith MJ, Sumner JC, Sutton RR, Sweckard L, Talbott NB, Traxler PA, Truesdell J, Valenti AF, Verace L, Vijayakumar P, Wadley WL, Walter KE, Williams AR, Wilson TJ, Witbeck MA, Wobler TM, Wright LJ, Zuczkowska KA, Devergne O, Hamill DR, Shah HP, Siders J, Taylor EE, Vrailas-Mortimer AD, Kagey JD. Genetic mapping of Uba3 O.2.2 , a pupal lethal mutation in Drosophila melanogaster. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000542. [PMID: 35622528 PMCID: PMC9012533 DOI: 10.17912/micropub.biology.000542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 11/11/2022]
Abstract
An EMS mutagenesis screen was conducted in
Drosophila melanogaster
to identify growth control mutants. The multi-institution Fly-CURE consortium phenotypically characterized the
O.2.2
mutant using the
FLP/FRT
system which displayed a mutant lethal phenotype with reduced head development, and darkened ocular tissue. Complementation mapping was conducted to identify the affected gene. A failure to complement was identified in
Uba3
, resulting in the identification of the novel allele,
Uba3
O.2.2
.
Uba3
is a known disruptor of the cell cycle and our data are consistent with early larval/embryonic lethality displayed in numerous species.
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Affiliation(s)
| | - Kayla L Bieser
- Nevada State College
,
Correspondence to: Kayla L Bieser (
)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Jacob D Kagey
- University of Detroit Mercy
,
Correspondence to: Jacob D Kagey (
)
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4
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Barbosa P, Zhaunova L, Debilio S, Steccanella V, Kelly V, Ly T, Ohkura H. SCF-Fbxo42 promotes synaptonemal complex assembly by downregulating PP2A-B56. J Cell Biol 2020; 220:211645. [PMID: 33382409 PMCID: PMC7780726 DOI: 10.1083/jcb.202009167] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/20/2020] [Accepted: 12/02/2020] [Indexed: 12/27/2022] Open
Abstract
Meiosis creates genetic diversity by recombination and segregation of chromosomes. The synaptonemal complex assembles during meiotic prophase I and assists faithful exchanges between homologous chromosomes, but how its assembly/disassembly is regulated remains to be understood. Here, we report how two major posttranslational modifications, phosphorylation and ubiquitination, cooperate to promote synaptonemal complex assembly. We found that the ubiquitin ligase complex SCF is important for assembly and maintenance of the synaptonemal complex in Drosophila female meiosis. This function of SCF is mediated by two substrate-recognizing F-box proteins, Slmb/βTrcp and Fbxo42. SCF-Fbxo42 down-regulates the phosphatase subunit PP2A-B56, which is important for synaptonemal complex assembly and maintenance.
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Affiliation(s)
- Pedro Barbosa
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Liudmila Zhaunova
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Simona Debilio
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK,Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Verdiana Steccanella
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Van Kelly
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Tony Ly
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Hiroyuki Ohkura
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK,Correspondence to Hiroyuki Ohkura:
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5
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Xie L, Ji X, Tu Y, Wang K, Zhu L, Zeng X, Wang X, Zhang J, Zhu M. MLN4924 inhibits hedgehog signaling pathway and activates autophagy to alleviate mouse laser-induced choroidal neovascularization lesion. Biomed Pharmacother 2020; 130:110654. [PMID: 34321162 DOI: 10.1016/j.biopha.2020.110654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 10/23/2022] Open
Abstract
Neovascular age-related macular degeneration (nAMD), featured as choroidal neovascularization (CNV), can cause blindness in the elderly population. MLN4924, a highly selective small-molecule inhibitor of NEDD8 (neuronal precursor cell-expressed developmentally down-regulated protein 8)-activating enzyme (NAE), inhibits the proliferation, angiogenesis and inflammation of multiple cancers via up-regulating hedgehog pathway-regulated autophagy. MLN4924 intraperitoneal injection mitigated the leakage, area and volume of mouse laser-induced CNV lesion. Additionally, compared to CNV 7 d group, MLN4924 treated mouse retina-retinal pigment epithelium (RPE)-choroid complex showed decreased expression of hedgehog pathway-associated molecules patched 1 (PTCH1), smoothened (SMO), GLI family zinc finger 1 (GLI1) and GLI family zinc finger 2 (GLI2) with increased expression of autophagy-associated molecules sequestosome 1 (p62) and LC microtubule-associated protein 1 light chain 3 (LC3). Meanwhile, human choroidal endothelial cells (HCECs) exposed to hypoxia condition also showed decreased expression of hedgehog pathway-associated molecules and increased expression of autophagy-associated molecules. Compared to hypoxia + MLN4924 group, SMO agonist SAG up-regulated hedgehog pathway and down-regulated autophagy, whereas autophagy inhibitor PIK-III inhibited autophagy with no effect on hedgehog pathway, indicating that MLN4924 facilitated autophagy of HCECs via hindering hedgehog pathway under hypoxia condition. Finally, MLN4924 inhibited proliferation, migration and tube formation of HCECs via boosting hedgehog pathway-regulated autophagy. In summary, MLN4924 relieved the formation of mouse laser-induced CNV lesion might via up-regulating hedgehog pathway-regulated autophagy. The results provide a potential interfering strategy for nAMD targeting the autophagy of choroidal endothelial cells.
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Affiliation(s)
- Laiqing Xie
- Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Xiaoyan Ji
- Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Yuanyuan Tu
- Department of Ophthalmology, Lixiang Eye Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Kun Wang
- Department of Ophthalmology, Lixiang Eye Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Linling Zhu
- Department of Ophthalmology, Lixiang Eye Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Xinwei Zeng
- Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Xue Wang
- Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Ji Zhang
- Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
| | - Manhui Zhu
- Department of Ophthalmology, Lixiang Eye Hospital of Soochow University, Suzhou, Jiangsu, China.
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6
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Zavortink M, Rutt LN, Dzitoyeva S, Henriksen JC, Barrington C, Bilodeau DY, Wang M, Chen XXL, Rissland OS. The E2 Marie Kondo and the CTLH E3 ligase clear deposited RNA binding proteins during the maternal-to-zygotic transition. eLife 2020; 9:53889. [PMID: 32573431 PMCID: PMC7384856 DOI: 10.7554/elife.53889] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 06/23/2020] [Indexed: 12/12/2022] Open
Abstract
The maternal-to-zygotic transition (MZT) is a conserved step in animal development, where control is passed from the maternal to the zygotic genome. Although the MZT is typically considered from its impact on the transcriptome, we previously found that three maternally deposited Drosophila RNA-binding proteins (ME31B, Trailer Hitch [TRAL], and Cup) are also cleared during the MZT by unknown mechanisms. Here, we show that these proteins are degraded by the ubiquitin-proteasome system. Marie Kondo, an E2 conjugating enzyme, and the E3 CTLH ligase are required for the destruction of ME31B, TRAL, and Cup. Structure modeling of the Drosophila CTLH complex suggests that substrate recognition is different than orthologous complexes. Despite occurring hours earlier, egg activation mediates clearance of these proteins through the Pan Gu kinase, which stimulates translation of Kdo mRNA. Clearance of the maternal protein dowry thus appears to be a coordinated, but as-yet underappreciated, aspect of the MZT. Bestselling author and organizing consultant Marie Kondo has helped people around the world declutter their homes by getting rid of physical items that do not bring them joy. Keeping the crowded environment inside a living cell organized also requires work and involves removing molecules that are no longer needed. A fertilized egg cell, for example, contains molecules from the mother that regulate the initial stages as it develops into an embryo. Later on, the embryo takes control of its own development by destroying these inherited molecules and switches to making its own instead. This process is called the maternal-to-zygotic transition. The molecules passed from the mother to the egg cell include proteins and messenger RNAs (molecules that include the coded instructions to make new proteins). Previous research has begun to reveal how the embryo destroys the mRNAs it inherits from its mother and how it starts to make its own. Yet almost nothing is known about how an embryo gets rid of its mother’s proteins. To address this question, Zavortink, Rutt, Dzitoyeva et al. used an approach known as an RNA interference screen to identify factors required to destroy three maternal proteins in fruit fly embryos. The experiments helped identify one enzyme that worked together with another larger enzyme complex to destroy the maternal proteins. This enzyme belongs to a class of enzymes known as ubiquitin-conjugating enzymes (or E2 enzymes) and it was given the name “Kdo”, short for “Marie Kondo”. Further experiments showed that the mRNAs that code for the Kdo enzyme were present in unfertilized eggs, but in a repressed state that prevented the eggs from making the enzyme. Once an egg started to develop into an embryo, these mRNAs became active and the embryo started to make Kdo enzymes. This led to the three maternal proteins being destroyed during the maternal-to-zygotic transition. These findings reveal a new pathway that regulates the destruction of maternal proteins as the embryo develops. The next challenge will be identifying other maternal proteins that do not “spark joy” and understanding the role their destruction plays in the earliest events of embryonic development.
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Affiliation(s)
| | - Lauren N Rutt
- University of Colorado School of Medicine, Aurora, United States
| | | | | | - Chloe Barrington
- University of Colorado School of Medicine, Aurora, United States
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7
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Ketosugbo KF, Bushnell HL, Johnson RI. A screen for E3 ubiquitination ligases that genetically interact with the adaptor protein Cindr during Drosophila eye patterning. PLoS One 2017; 12:e0187571. [PMID: 29117266 PMCID: PMC5678704 DOI: 10.1371/journal.pone.0187571] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 10/23/2017] [Indexed: 01/12/2023] Open
Abstract
Ubiquitination is a crucial post-translational modification that can target proteins for degradation. The E3 ubiquitin ligases are responsible for recognizing substrate proteins for ubiquitination, hence providing specificity to the process of protein degradation. Here, we describe a genetic modifier screen that identified E3 ligases that modified the rough-eye phenotype generated by expression of cindrRNAi transgenes during Drosophila eye development. In total, we identified 36 E3 ligases, as well as 4 Cullins, that modified the mild cindrRNA mis-patterning phenotype. This indicates possible roles for these E3s/Cullins in processes that require Cindr function, including cytoskeletal regulation, cell adhesion, cell signaling and cell survival. Three E3 ligases identified in our screen had previously been linked to regulating JNK signaling.
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Affiliation(s)
- Kwami F. Ketosugbo
- Biology Department, Wesleyan University, Middletown, Connecticut, United States of America
| | - Henry L. Bushnell
- Biology Department, Wesleyan University, Middletown, Connecticut, United States of America
| | - Ruth I. Johnson
- Biology Department, Wesleyan University, Middletown, Connecticut, United States of America
- * E-mail:
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8
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Du J, Zhang J, He T, Li Y, Su Y, Tie F, Liu M, Harte PJ, Zhu AJ. Stuxnet Facilitates the Degradation of Polycomb Protein during Development. Dev Cell 2017; 37:507-19. [PMID: 27326929 DOI: 10.1016/j.devcel.2016.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
Polycomb-group (PcG) proteins function to ensure correct deployment of developmental programs by epigenetically repressing target gene expression. Despite the importance, few studies have been focused on the regulation of PcG activity itself. Here, we report a Drosophila gene, stuxnet (stx), that controls Pc protein stability. We find that heightened stx activity leads to homeotic transformation, reduced Pc activity, and de-repression of PcG targets. Conversely, stx mutants, which can be rescued by decreased Pc expression, display developmental defects resembling hyperactivation of Pc. Our biochemical analyses provide a mechanistic basis for the interaction between stx and Pc; Stx facilitates Pc degradation in the proteasome, independent of ubiquitin modification. Furthermore, this mode of regulation is conserved in vertebrates. Mouse stx promotes degradation of Cbx4, an orthologous Pc protein, in vertebrate cells and induces homeotic transformation in Drosophila. Our results highlight an evolutionarily conserved mechanism of regulated protein degradation on PcG homeostasis and epigenetic activity.
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Affiliation(s)
- Juan Du
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Junzheng Zhang
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Tao He
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yajuan Li
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Ying Su
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Feng Tie
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Min Liu
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Peter J Harte
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Alan Jian Zhu
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
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9
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Schunter S, Villa R, Flynn V, Heidelberger JB, Classen AK, Beli P, Becker PB. Ubiquitylation of the acetyltransferase MOF in Drosophila melanogaster. PLoS One 2017; 12:e0177408. [PMID: 28510597 PMCID: PMC5433716 DOI: 10.1371/journal.pone.0177408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/26/2017] [Indexed: 01/26/2023] Open
Abstract
The nuclear acetyltransferase MOF (KAT8 in mammals) is a subunit of at least two multi-component complexes involved in transcription regulation. In the context of complexes of the ‘Non-Specific-Lethal’ (NSL) type it controls transcription initiation of many nuclear housekeeping genes and of mitochondrial genes. While this function is conserved in metazoans, MOF has an additional, specific function in Drosophila in the context of dosage compensation. As a subunit of the male-specific-lethal dosage compensation complex (MSL-DCC) it contributes to the doubling of transcription output from the single male X chromosome by acetylating histone H4. Proper dosage compensation requires finely tuned levels of MSL-DCC and an appropriate distribution of MOF between the regulatory complexes. The amounts of DCC formed depends directly on the levels of the male-specific MSL2, which orchestrates the assembly of the DCC, including MOF recruitment. We found earlier that MSL2 is an E3 ligase that ubiquitylates most MSL proteins, including MOF, suggesting that ubiquitylation may contribute to a quality control of MOF’s overall levels and folding state as well as its partitioning between the complex entities. We now used mass spectrometry to map the lysines in MOF that are ubiquitylated by MSL2 in vitro and identified in vivo ubiquitylation sites of MOF in male and female cells. MSL2-specific ubiquitylation in vivo could not be traced due to the dominance of other, sex-independent ubiquitylation events and conceivably may be rare or transient. Expressing appropriately mutated MOF derivatives we assessed the importance of the ubiquitylated lysines for dosage compensation by monitoring DCC formation and X chromosome targeting in cultured cells, and by genetic complementation of the male-specific-lethal mof2 allele in flies. Our study provides a comprehensive analysis of MOF ubiquitylation as a reference for future studies.
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Affiliation(s)
- Sarah Schunter
- Molecular Biology Division, Biomedical Center and Center for integrated Protein Science Ludwig-Maximilians-University, Munich, Germany
| | - Raffaella Villa
- Molecular Biology Division, Biomedical Center and Center for integrated Protein Science Ludwig-Maximilians-University, Munich, Germany
| | - Victoria Flynn
- Molecular Biology Division, Biomedical Center and Center for integrated Protein Science Ludwig-Maximilians-University, Munich, Germany
| | | | | | - Petra Beli
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Peter B. Becker
- Molecular Biology Division, Biomedical Center and Center for integrated Protein Science Ludwig-Maximilians-University, Munich, Germany
- * E-mail:
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10
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Abstract
The Hedgehog (Hh) signaling pathway play critical roles in embryonic development and adult tissue homeostasis. A critical step in Hh signal transduction is how Hh receptor Patched (Ptc) inhibits the atypical G protein-coupled receptor Smoothened (Smo) in the absence of Hh and how this inhibition is release by Hh stimulation. It is unlikely that Ptc inhibits Smo by direct interaction. Here we discuss how Hh regulates the phosphorylation and ubiquitination of Smo, leading to cell surface and ciliary accumulation of Smo in Drosophila and vertebrate cells, respectively. In addition, we discuss how PI(4)P phospholipid acts in between Ptc and Smo to regulate Smo phosphorylation and activation in response to Hh stimulation.
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Affiliation(s)
- Kai Jiang
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Jianhang Jia
- Markey Cancer Center, Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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11
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Dean DM, Maroja LS, Cottrill S, Bomkamp BE, Westervelt KA, Deitcher DL. The wavy Mutation Maps to the Inositol 1,4,5-Trisphosphate 3-Kinase 2 (IP3K2) Gene of Drosophila and Interacts with IP3R to Affect Wing Development. G3 (BETHESDA, MD.) 2015; 6:299-310. [PMID: 26613949 PMCID: PMC4751550 DOI: 10.1534/g3.115.024307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 11/24/2015] [Indexed: 12/31/2022]
Abstract
Inositol 1,4,5-trisphosphate (IP3) regulates a host of biological processes from egg activation to cell death. When IP3-specific receptors (IP3Rs) bind to IP3, they release calcium from the ER into the cytoplasm, triggering a variety of cell type- and developmental stage-specific responses. Alternatively, inositol polyphosphate kinases can phosphorylate IP3; this limits IP3R activation by reducing IP3 levels, and also generates new signaling molecules altogether. These divergent pathways draw from the same IP3 pool yet cause very different cellular responses. Therefore, controlling the relative rates of IP3R activation vs. phosphorylation of IP3 is essential for proper cell functioning. Establishing a model system that sensitively reports the net output of IP3 signaling is crucial for identifying the controlling genes. Here we report that mutant alleles of wavy (wy), a classic locus of the fruit fly Drosophila melanogaster, map to IP3 3-kinase 2 (IP3K2), a member of the inositol polyphosphate kinase gene family. Mutations in wy disrupt wing structure in a highly specific pattern. RNAi experiments using GAL4 and GAL80(ts) indicated that IP3K2 function is required in the wing discs of early pupae for normal wing development. Gradations in the severity of the wy phenotype provide high-resolution readouts of IP3K2 function and of overall IP3 signaling, giving this system strong potential as a model for further study of the IP3 signaling network. In proof of concept, a dominant modifier screen revealed that mutations in IP3R strongly suppress the wy phenotype, suggesting that the wy phenotype results from reduced IP4 levels, and/or excessive IP3R signaling.
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Affiliation(s)
- Derek M Dean
- Department of Biology, Williams College, Williamstown, Massachusetts 01267
| | - Luana S Maroja
- Department of Biology, Williams College, Williamstown, Massachusetts 01267
| | - Sarah Cottrill
- Department of Biology, Williams College, Williamstown, Massachusetts 01267
| | - Brent E Bomkamp
- Department of Biology, Williams College, Williamstown, Massachusetts 01267
| | | | - David L Deitcher
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
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12
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Gargiulo G, Serresi M, Cesaroni M, Hulsman D, van Lohuizen M. In vivo shRNA screens in solid tumors. Nat Protoc 2014; 9:2880-902. [PMID: 25411954 DOI: 10.1038/nprot.2014.185] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Loss-of-function (LOF) experiments targeting multiple genes during tumorigenesis can be implemented using pooled shRNA libraries. RNAi screens in animal models rely on the use of multiple shRNAs to simultaneously disrupt gene function, as well as to serve as barcodes for cell fate outcomes during tumorigenesis. Here we provide a protocol for performing RNAi screens in orthotopic mouse tumor models, referring to glioma and lung adenocarcinoma as specific examples. The protocol aims to provide guidelines for applying RNAi to a diverse spectrum of solid tumors and to highlight crucial considerations when designing and performing these studies. It covers shRNA library assembly and packaging into lentiviral particles, and transduction into tumor-initiating cells (TICs), followed by in vivo transplantation, tumor DNA recovery, sequencing and analysis. Depending on the target genes and tumor model, tumor suppressors and oncogenes can be identified or biological pathways can be dissected in 6-9 weeks.
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Affiliation(s)
- Gaetano Gargiulo
- Division of Molecular Genetics, the Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Michela Serresi
- Division of Molecular Genetics, the Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Matteo Cesaroni
- Fels Institute, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Danielle Hulsman
- Division of Molecular Genetics, the Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Maarten van Lohuizen
- 1] Division of Molecular Genetics, the Netherlands Cancer Institute, Amsterdam, the Netherlands. [2] Cancer Genomics Centre, the Netherlands
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Zhang J, Du J, Lei C, Liu M, Zhu AJ. Ubpy controls the stability of the ESCRT-0 subunit Hrs in development. Development 2014; 141:1473-9. [PMID: 24574010 DOI: 10.1242/dev.099564] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ubiquitylated developmental membrane signaling proteins are often internalized for endocytic trafficking, through which endosomal sorting complexes required for transport (ESCRT) act sequentially to deliver internalized cargos to lysosomes. The ESCRT function in endocytic sorting is well established; however, it is not fully understood how the sorting machinery itself is regulated. Here, we show that Ubiquitin isopeptidase Y (Ubpy) plays a conserved role in vivo in the homeostasis of an essential ESCRT-0 complex component Hrs. We find that, in the absence of Drosophila Ubpy, multiple membrane proteins that are essential components of important signaling pathways accumulate in enlarged, aberrant endosomes. We further demonstrate that this phenotype results from endocytic pathway defects. We provide evidence that Ubpy interacts with and deubiquitylates Hrs. In Ubpy-null cells, Hrs becomes ubiquitylated and degraded in lysosomes, thus disrupting the integrity of ESCRT sorting machinery. Lastly, we find that signaling proteins are enriched in enlarged endosomes when Hrs activity is abolished. Together, our data support a model in which Ubpy plays a dual role in both cargo deubiquitylation and the ESCRT-0 stability during development.
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Affiliation(s)
- Junzheng Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
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14
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Proteasome, but not autophagy, disruption results in severe eye and wing dysmorphia: a subunit- and regulator-dependent process in Drosophila. PLoS One 2013; 8:e80530. [PMID: 24282550 PMCID: PMC3839973 DOI: 10.1371/journal.pone.0080530] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/14/2013] [Indexed: 12/19/2022] Open
Abstract
Proteasome-dependent and autophagy-mediated degradation of eukaryotic cellular proteins represent the two major proteostatic mechanisms that are critically implicated in a number of signaling pathways and cellular processes. Deregulation of functions engaged in protein elimination frequently leads to development of morbid states and diseases. In this context, and through the utilization of GAL4/UAS genetic tool, we herein examined the in vivo contribution of proteasome and autophagy systems in Drosophila eye and wing morphogenesis. By exploiting the ability of GAL4-ninaE. GMR and P{GawB}BxMS1096 genetic drivers to be strongly and preferentially expressed in the eye and wing discs, respectively, we proved that proteasomal integrity and ubiquitination proficiency essentially control fly’s eye and wing development. Indeed, subunit- and regulator-specific patterns of severe organ dysmorphia were obtained after the RNAi-induced downregulation of critical proteasome components (Rpn1, Rpn2, α5, β5 and β6) or distinct protein-ubiquitin conjugators (UbcD6, but not UbcD1 and UbcD4). Proteasome deficient eyes presented with either rough phenotypes or strongly dysmorphic shapes, while transgenic mutant wings were severely folded and carried blistered structures together with loss of vein differentiation. Moreover, transgenic fly eyes overexpressing the UBP2-yeast deubiquitinase enzyme were characterized by an eyeless-like phenotype. Therefore, the proteasome/ubiquitin proteolytic activities are undoubtedly required for the normal course of eye and wing development. In contrast, the RNAi-mediated downregulation of critical Atg (1, 4, 7, 9 and 18) autophagic proteins revealed their non-essential, or redundant, functional roles in Drosophila eye and wing formation under physiological growth conditions, since their reduced expression levels could only marginally disturb wing’s, but not eye’s, morphogenetic organization and architecture. However, Atg9 proved indispensable for the maintenance of structural integrity of adult wings in aged flies. In toto, our findings clearly demonstrate the gene-specific fundamental contribution of proteasome, but not autophagy, in invertebrate eye and wing organ development.
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15
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In Vivo RNAi-Based Screens: Studies in Model Organisms. Genes (Basel) 2013; 4:646-65. [PMID: 24705267 PMCID: PMC3927573 DOI: 10.3390/genes4040646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 10/29/2013] [Accepted: 11/14/2013] [Indexed: 11/23/2022] Open
Abstract
RNA interference (RNAi) is a technique widely used for gene silencing in organisms and cultured cells, and depends on sequence homology between double-stranded RNA (dsRNA) and target mRNA molecules. Numerous cell-based genome-wide screens have successfully identified novel genes involved in various biological processes, including signal transduction, cell viability/death, and cell morphology. However, cell-based screens cannot address cellular processes such as development, behavior, and immunity. Drosophila and Caenorhabditis elegans are two model organisms whose whole bodies and individual body parts have been subjected to RNAi-based genome-wide screening. Moreover, Drosophila RNAi allows the manipulation of gene function in a spatiotemporal manner when it is implemented using the Gal4/UAS system. Using this inducible RNAi technique, various large-scale screens have been performed in Drosophila, demonstrating that the method is straightforward and valuable. However, accumulated results reveal that the results of RNAi-based screens have relatively high levels of error, such as false positives and negatives. Here, we review in vivo RNAi screens in Drosophila and the methods that could be used to remove ambiguity from screening results.
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16
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Chai YJ, Kim D, Park J, Zhao H, Lee SJ, Chang S. The secreted oligomeric form of α-synuclein affects multiple steps of membrane trafficking. FEBS Lett 2013; 587:452-9. [PMID: 23333298 DOI: 10.1016/j.febslet.2013.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/10/2012] [Accepted: 01/02/2013] [Indexed: 01/05/2023]
Abstract
α-Synuclein (α-syn) can be secreted from neurons into the extracellular space, affecting the homeostasis of neighboring cells, but the pathophysiology of secreted α-syn remains largely unknown. We found that when exogenously applied to COS-7 cells, α-syn secreted from differentiated SH-SY5Y cells was taken up by dynamin-dependent endocytosis. Upon internalization, α-syn significantly increased the rate of transferrin receptor (TfR) internalization and recycling, and subsequently the surface levels of TfR. The effects are attributable to the oligomeric form, but not monomeric or fibrillar form, of extracellular α-syn. Together, multiple alterations in membrane trafficking by secreted oligomeric α-syn may contribute to the early stages of pathogenesis in Parkinson's disease.
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Affiliation(s)
- Ye-Jin Chai
- Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea
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17
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A targeted in vivo RNAi screen reveals deubiquitinases as new regulators of Notch signaling. G3-GENES GENOMES GENETICS 2012; 2:1563-75. [PMID: 23275879 PMCID: PMC3516478 DOI: 10.1534/g3.112.003780] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 09/27/2012] [Indexed: 01/11/2023]
Abstract
Notch signaling is highly conserved in all metazoan animals and plays critical roles in cell fate specification, cell proliferation, apoptosis, and stem cell maintenance. Although core components of the Notch signaling cascade have been identified, many gaps in the understanding of the Notch signaling pathway remain to be filled. One form of posttranslational regulation, which is controlled by the ubiquitin-proteasome system, is known to modulate Notch signaling. The ubiquitination pathway is a highly coordinated process in which the ubiquitin moiety is either conjugated to or removed from target proteins by opposing E3 ubiquitin ligases and deubiquitinases (DUBs). Several E3 ubiquitin ligases have been implicated in ubiquitin conjugation to the receptors and the ligands of the Notch signaling cascade. In contrast, little is known about a direct role of DUBs in Notch signaling in vivo. Here, we report an in vivo RNA interference screen in Drosophila melanogaster targeting all 45 DUBs that we annotated in the fly genome. We show that at least four DUBs function specifically in the formation of the fly wing margin and/or the specification of the scutellar sensory organ precursors, two processes that are strictly dependent on the balanced Notch signaling activity. Furthermore, we provide genetic evidence suggesting that these DUBs are necessary to positively modulate Notch signaling activity. Our study reveals a conserved molecular mechanism by which protein deubiquitination process contributes to the complex posttranslational regulation of Notch signaling in vivo.
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18
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Cajee UF, Hull R, Ntwasa M. Modification by ubiquitin-like proteins: significance in apoptosis and autophagy pathways. Int J Mol Sci 2012; 13:11804-11831. [PMID: 23109884 PMCID: PMC3472776 DOI: 10.3390/ijms130911804] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/11/2012] [Accepted: 09/13/2012] [Indexed: 01/31/2023] Open
Abstract
Ubiquitin-like proteins (Ubls) confer diverse functions on their target proteins. The modified proteins are involved in various biological processes, including DNA replication, signal transduction, cell cycle control, embryogenesis, cytoskeletal regulation, metabolism, stress response, homeostasis and mRNA processing. Modifiers such as SUMO, ATG12, ISG15, FAT10, URM1, and UFM have been shown to modify proteins thus conferring functions related to programmed cell death, autophagy and regulation of the immune system. Putative modifiers such as Domain With No Name (DWNN) have been identified in recent times but not fully characterized. In this review, we focus on cellular processes involving human Ubls and their targets. We review current progress in targeting these modifiers for drug design strategies.
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Affiliation(s)
- Umar-Faruq Cajee
- School of Molecular & Cell Biology, Gatehouse 512, University of the Witwatersrand, Johannesburg, 2050, South Africa; E-Mails: (U.-F.C.); (R.H.)
| | - Rodney Hull
- School of Molecular & Cell Biology, Gatehouse 512, University of the Witwatersrand, Johannesburg, 2050, South Africa; E-Mails: (U.-F.C.); (R.H.)
| | - Monde Ntwasa
- School of Molecular & Cell Biology, Gatehouse 512, University of the Witwatersrand, Johannesburg, 2050, South Africa; E-Mails: (U.-F.C.); (R.H.)
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