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Xia QQ, Singh A, Wang J, Xuan ZX, Singer JD, Powell CM. Autism risk gene Cul3 alters neuronal morphology via caspase-3 activity in mouse hippocampal neurons. Front Cell Neurosci 2024; 18:1320784. [PMID: 38803442 PMCID: PMC11129687 DOI: 10.3389/fncel.2024.1320784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/15/2024] [Indexed: 05/29/2024] Open
Abstract
Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders (NDDs) in which children display differences in social interaction/communication and repetitive stereotyped behaviors along with variable associated features. Cul3, a gene linked to ASD, encodes CUL3 (CULLIN-3), a protein that serves as a key component of a ubiquitin ligase complex with unclear function in neurons. Cul3 homozygous deletion in mice is embryonic lethal; thus, we examine the role of Cul3 deletion in early synapse development and neuronal morphology in hippocampal primary neuronal cultures. Homozygous deletion of Cul3 significantly decreased dendritic complexity and dendritic length, as well as axon formation. Synaptic spine density significantly increased, mainly in thin and stubby spines along with decreased average spine volume in Cul3 knockouts. Both heterozygous and homozygous knockout of Cul3 caused significant reductions in the density and colocalization of gephyrin/vGAT puncta, providing evidence of decreased inhibitory synapse number, while excitatory synaptic puncta vGulT1/PSD95 density remained unchanged. Based on previous studies implicating elevated caspase-3 after Cul3 deletion, we demonstrated increased caspase-3 in our neuronal cultures and decreased neuronal cell viability. We then examined the efficacy of the caspase-3 inhibitor Z-DEVD-FMK to rescue the decrease in neuronal cell viability, demonstrating reversal of the cell viability phenotype with caspase-3 inhibition. Studies have also implicated caspase-3 in neuronal morphological changes. We found that caspase-3 inhibition largely reversed the dendrite, axon, and spine morphological changes along with the inhibitory synaptic puncta changes. Overall, these data provide additional evidence that Cul3 regulates the formation or maintenance of cell morphology, GABAergic synaptic puncta, and neuronal viability in developing hippocampal neurons in culture.
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Affiliation(s)
- Qiang-qiang Xia
- Department of Neurobiology, Marnix E. Heersink School of Medicine & Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Anju Singh
- Department of Neurobiology, Marnix E. Heersink School of Medicine & Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jing Wang
- Department of Neurobiology, Marnix E. Heersink School of Medicine & Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Zhong Xin Xuan
- Department of Neurobiology, Marnix E. Heersink School of Medicine & Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jeffrey D. Singer
- Department of Biology, Portland State University, Portland, OR, United States
| | - Craig M. Powell
- Department of Neurobiology, Marnix E. Heersink School of Medicine & Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL, United States
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2
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Tener SJ, Lin Z, Park SJ, Oraedu K, Ulgherait M, Van Beek E, Martínez-Muñiz A, Pantalia M, Gatto JA, Volpi J, Stavropoulos N, Ja WW, Canman JC, Shirasu-Hiza M. Neuronal knockdown of Cullin3 as a Drosophila model of autism spectrum disorder. Sci Rep 2024; 14:1541. [PMID: 38233464 PMCID: PMC10794434 DOI: 10.1038/s41598-024-51657-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 01/06/2024] [Indexed: 01/19/2024] Open
Abstract
Mutations in Cullin-3 (Cul3), a conserved gene encoding a ubiquitin ligase, are strongly associated with autism spectrum disorder (ASD). Here, we characterize ASD-related pathologies caused by neuron-specific Cul3 knockdown in Drosophila. We confirmed that neuronal Cul3 knockdown causes short sleep, paralleling sleep disturbances in ASD. Because sleep defects and ASD are linked to metabolic dysregulation, we tested the starvation response of neuronal Cul3 knockdown flies; they starved faster and had lower triacylglyceride levels than controls, suggesting defects in metabolic homeostasis. ASD is also characterized by increased biomarkers of oxidative stress; we found that neuronal Cul3 knockdown increased sensitivity to hyperoxia, an exogenous oxidative stress. Additional hallmarks of ASD are deficits in social interactions and learning. Using a courtship suppression assay that measures social interactions and memory of prior courtship, we found that neuronal Cul3 knockdown reduced courtship and learning compared to controls. Finally, we found that neuronal Cul3 depletion alters the anatomy of the mushroom body, a brain region required for memory and sleep. Taken together, the ASD-related phenotypes of neuronal Cul3 knockdown flies establish these flies as a genetic model to study molecular and cellular mechanisms underlying ASD pathology, including metabolic and oxidative stress dysregulation and neurodevelopment.
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Affiliation(s)
- Samantha J Tener
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Zhi Lin
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Scarlet J Park
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, 33458, USA
| | - Kairaluchi Oraedu
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Matthew Ulgherait
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Emily Van Beek
- Waksman Institute, Rutgers University, Piscataway, NJ, 08854, USA
| | - Andrés Martínez-Muñiz
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Meghan Pantalia
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Jared A Gatto
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Julia Volpi
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | | | - William W Ja
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, 33458, USA
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Mimi Shirasu-Hiza
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, 10032, USA.
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3
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Song JM, Kang M, Lee S, Kim J, Park S, Park DH, Lee S, Suh YH. Deneddylating enzyme SENP8 regulates neuronal development. J Neurochem 2023; 165:348-361. [PMID: 36847487 DOI: 10.1111/jnc.15797] [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: 10/15/2022] [Revised: 01/16/2023] [Accepted: 02/13/2023] [Indexed: 03/01/2023]
Abstract
Neddylation is a cellular process in which the neural precursor cell expressed, developmentally down-regulated 8 (NEDD8) is conjugated to the lysine residue of target proteins via serial enzymatic cascades. Recently, it has been demonstrated that neddylation is required for synaptic clustering of metabotropic glutamate receptor 7 (mGlu7) and postsynaptic density protein 95 (PSD-95), and the inhibition of neddylation impairs neurite outgrowth and excitatory synaptic maturation. Similar to the balanced role of deubiquitylating enzymes (DUBs) in the ubiquitination process, we hypothesized that deneddylating enzymes can regulate neuronal development by counteracting the process of neddylation. We find that the SUMO peptidase family member, NEDD8 specific (SENP8) acts as a key neuronal deneddylase targeting the global neuronal substrates in primary rat cultured neurons. We demonstrate that SENP8 expression levels are developmentally regulated, peaking around the first postnatal week and gradually diminishing in mature brain and neurons. We find that SENP8 negatively regulates neurite outgrowth through multiple pathways, including actin dynamics, Wnt/β-catenin signaling, and autophagic processes. Alterations in neurite outgrowth by SENP8 subsequently result in the impairment of excitatory synapse maturation. Our data indicate that SENP8 plays an essential role in neuronal development and is a promising therapeutic target for neurodevelopmental disorders.
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Affiliation(s)
- Jae-Man Song
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Minji Kang
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Seungha Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Jungho Kim
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Sunha Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Da-Ha Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Sanghyeon Lee
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Young Ho Suh
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, South Korea.,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.,Transplantation Research Institute, Seoul National University College of Medicine, Seoul, South Korea
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4
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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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5
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Li Q, Jang H, Lim KY, Lessing A, Stavropoulos N. insomniac links the development and function of a sleep-regulatory circuit. eLife 2021; 10:65437. [PMID: 34908527 PMCID: PMC8758140 DOI: 10.7554/elife.65437] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
Although many genes are known to influence sleep, when and how they impact sleep-regulatory circuits remain ill-defined. Here, we show that insomniac (inc), a conserved adaptor for the autism-associated Cul3 ubiquitin ligase, acts in a restricted period of neuronal development to impact sleep in adult Drosophila. The loss of inc causes structural and functional alterations within the mushroom body (MB), a center for sensory integration, associative learning, and sleep regulation. In inc mutants, MB neurons are produced in excess, develop anatomical defects that impede circuit assembly, and are unable to promote sleep when activated in adulthood. Our findings link neurogenesis and postmitotic development of sleep-regulatory neurons to their adult function and suggest that developmental perturbations of circuits that couple sensory inputs and sleep may underlie sleep dysfunction in neurodevelopmental disorders.
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Affiliation(s)
- Qiuling Li
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Hyunsoo Jang
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Kayla Y Lim
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Alexie Lessing
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
| | - Nicholas Stavropoulos
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of MedicineNew YorkUnited States
- Waksman Institute, Rutgers UniversityPiscatawayUnited States
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6
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Yang M, Guo Y, Wang S, Chen C, Chang YH, Ho MSC. The F-Box Protein CG5003 Regulates Axon Pruning and the Integrity of the Drosophila Mushroom Body. Front Mol Neurosci 2021; 14:634784. [PMID: 33716667 PMCID: PMC7947810 DOI: 10.3389/fnmol.2021.634784] [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: 11/28/2020] [Accepted: 01/27/2021] [Indexed: 11/25/2022] Open
Abstract
Protein homeostasis serves as an important step in regulating diverse cellular processes underlying the function and development of the nervous system. In particular, the ubiquitination proteasome system (UPS), a universal pathway mediating protein degradation, contributes to the development of numerous synaptic structures, including the Drosophila olfactory-associative learning center mushroom body (MB), thereby affecting associated function. Here, we describe the function of a newly characterized Drosophila F-box protein CG5003, an adaptor for the RING-domain type E3 ligase (SCF complex), in MB development. Lacking CG5003 ubiquitously causes MB γ axon pruning defects and selective CG5003 expression in pan-neurons leads to both γ axon and α/β lobe abnormalities. Interestingly, change in CG5003 expression in MB neurons does not cause any abnormalities in axons, suggesting that CG5003 functions in cells extrinsic to MB to regulate its development. Mass spectrum analysis indicates that silencing CG5003 expression in all neurons affects expression levels of proteins in the cell and structural morphogenesis, transcription regulator activity, and catalytic activity. Our findings reinforce the importance of UPS and identify a new factor in regulating neuronal development as exemplified by the synaptic structure MB.
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Affiliation(s)
- Mengying Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yige Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Shuran Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Changyan Chen
- Institute of Intervention Vessel, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Yung-Heng Chang
- Department of Anesthesiology, Stony Brook School of Medicine, New York, NY, United States
| | - Margaret Su-Chun Ho
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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7
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Zhang B, Xu R, Fang G, Zhao Y. 20-HETE downregulates Na/K-ATPase α1 expression via the ubiquitination pathway. Prostaglandins Other Lipid Mediat 2021; 152:106503. [PMID: 33199266 DOI: 10.1016/j.prostaglandins.2020.106503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 10/07/2020] [Accepted: 10/19/2020] [Indexed: 10/23/2022]
Abstract
In this article, we found that 20-Hydroxyeicosatetraenoic acid (20-HETE) reduced Na/K-ATPase α1 expression via the ubiquitin-proteasome pathway. The ubiquitination level of Na/K-ATPase α1 protein was increased in 20-HETE-treated mouse cortical collecting duct cells and the kidney tissues of CYP4F2 transgenic mice. We also demonstrated that 20-HETE-induced high level phosphorylation of Na/K-ATPase α1 was necessary for its ubiquitination.The protein kinase C inhibitor sotrastaurin significantly reduced the phosphorylation of Na/K-ATPase α1 and increased the expression of Na/K-ATPase α1 although 20-HETE stimulus being applied at the same time. Moreover, high level of 20-HETE increased the expression and neddylation of Cullin3,which is an important ubiquitin E3 ligase in kidney. MLN4924, an inhibitor of NEDD8-activating enzyme, inhibited neddylation of Cullin3 and reversed the reduction of Na/K-ATPase α1 expression caused by 20-HETE. Thus, 20-HETE downregulates Na/K-ATPase α1 via the ubiquitination pathway, and phosphorylation of Na/K-ATPase α1 is a prerequisite to ubiquitination. Additionally, 20-HETE regulates Cullin3 expression via neddylation.
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Affiliation(s)
- Bijun Zhang
- Department of Clinical Genetics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Runhong Xu
- Genet Lab, Maternal & Child Health Hospital of Hubei Province, Hubei, China
| | - Guicun Fang
- Department of Clinical Genetics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yanyan Zhao
- Department of Clinical Genetics, Shengjing Hospital of China Medical University, Shenyang, China.
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8
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Puñal VM, Ahmed M, Thornton-Kolbe EM, Clowney EJ. Untangling the wires: development of sparse, distributed connectivity in the mushroom body calyx. Cell Tissue Res 2021; 383:91-112. [PMID: 33404837 PMCID: PMC9835099 DOI: 10.1007/s00441-020-03386-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/07/2020] [Indexed: 01/16/2023]
Abstract
Appropriate perception and representation of sensory stimuli pose an everyday challenge to the brain. In order to represent the wide and unpredictable array of environmental stimuli, principle neurons of associative learning regions receive sparse, combinatorial sensory inputs. Despite the broad role of such networks in sensory neural circuits, the developmental mechanisms underlying their emergence are not well understood. As mammalian sensory coding regions are numerically complex and lack the accessibility of simpler invertebrate systems, we chose to focus this review on the numerically simpler, yet functionally similar, Drosophila mushroom body calyx. We bring together current knowledge about the cellular and molecular mechanisms orchestrating calyx development, in addition to drawing insights from literature regarding construction of sparse wiring in the mammalian cerebellum. From this, we formulate hypotheses to guide our future understanding of the development of this critical perceptual center.
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Affiliation(s)
- Vanessa M. Puñal
- Department of Molecular, Cellular & Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, USA,Department of Molecular & Integrative Physiology, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Maria Ahmed
- Department of Molecular, Cellular & Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Emma M. Thornton-Kolbe
- Department of Molecular, Cellular & Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, USA,Neuroscience Graduate Program, The University of Michigan, Ann Arbor, MI 48109, USA
| | - E. Josephine Clowney
- Department of Molecular, Cellular & Developmental Biology, The University of Michigan, Ann Arbor, MI 48109, USA
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9
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Fischer S, Schlotthauer I, Kizner V, Macartney T, Dorner-Ciossek C, Gillardon F. Loss-of-function Mutations of CUL3, a High Confidence Gene for Psychiatric Disorders, Lead to Aberrant Neurodevelopment In Human Induced Pluripotent Stem Cells. Neuroscience 2020; 448:234-254. [PMID: 32890664 DOI: 10.1016/j.neuroscience.2020.08.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/25/2020] [Accepted: 08/20/2020] [Indexed: 12/12/2022]
Abstract
Both rare, high risk, loss-of-function mutations and common, low risk, genetic variants in the CUL3 gene are strongly associated with neuropsychiatric disorders. Network analyses of neuropsychiatric risk genes have shown high CUL3 expression in the prenatal human brain and an enrichment in neural precursor cells (NPCs) and cortical neurons. The role of CUL3 in human neurodevelopment however, is poorly understood. In the present study, we used CRISPR/Cas9 nickase to knockout CUL3 in human induced pluripotent stem cells (iPSCs). iPSCs were subsequently differentiated into cortical glutamatergic neurons using two different protocols and tested for structural/functional alterations. Immunocytochemical analysis and transcriptomic profiling revealed that pluripotency of heterozygous CUL3 knockout (KO) iPSCs remained unchanged compared to isogenic control iPSCs. Following small molecule-mediated differentiation into cortical glutamatergic neurons however, we detected a significant delay in transition from proliferating radial glia cells/NPCs to postmitotic neurons in CUL3 KO cultures. Notably, direct neural conversion of CUL3 KO iPSCs by lentiviral expression of Neurogenin-2 massively attenuated the neurodevelopmental delay. However, both optogenetic and electrical stimulation of induced neurons revealed decreased excitability in Cullin-3 deficient cultures, while basal synaptic transmission remained unchanged. Analysis of target gene expression pointed to alterations in FGF signaling in CUL3 KO NPCs, which is required for NPC proliferation and self-renewal, while RhoA and Notch signaling appeared unaffected. Our data provide first evidence for a major role of Cullin-3 in neuronal differentiation, and for neurodevelopmental deficits underlying neuropsychiatric disorders associated with CUL3 mutations.
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Affiliation(s)
- Sandra Fischer
- CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riss, Germany
| | - Ines Schlotthauer
- CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riss, Germany
| | - Valeria Kizner
- CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riss, Germany
| | - Thomas Macartney
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, University of Dundee, Dundee DD1 5EH, UK
| | - Cornelia Dorner-Ciossek
- CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riss, Germany
| | - Frank Gillardon
- CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, 88397 Biberach an der Riss, Germany.
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10
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Strand NS, Allen JM, Ghulam M, Taylor MR, Munday RK, Carrillo M, Movsesyan A, Zayas RM. Dissecting the function of Cullin-RING ubiquitin ligase complex genes in planarian regeneration. Dev Biol 2018; 433:210-217. [PMID: 29291974 DOI: 10.1016/j.ydbio.2017.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/25/2017] [Accepted: 10/11/2017] [Indexed: 12/26/2022]
Abstract
The ubiquitin system plays a role in nearly every aspect of eukaryotic cell biology. The enzymes responsible for transferring ubiquitin onto specific substrates are the E3 ubiquitin ligases, a large and diverse family of proteins, for which biological roles and target substrates remain largely undefined. Studies using model organisms indicate that ubiquitin signaling mediates key steps in developmental processes and tissue regeneration. Here, we used the freshwater planarian, Schmidtea mediterranea, to investigate the role of Cullin-RING ubiquitin ligase (CRL) complexes in stem cell regulation during regeneration. We identified six S. mediterranea cullin genes, and used RNAi to uncover roles for homologs of Cullin-1, -3 and -4 in planarian regeneration. The cullin-1 RNAi phenotype included defects in blastema formation, organ regeneration, lesions, and lysis. To further investigate the function of cullin-1-mediated cellular processes in planarians, we examined genes encoding the adaptor protein Skp1 and F-box substrate-recognition proteins that are predicted to partner with Cullin-1. RNAi against skp1 resulted in phenotypes similar to cullin-1 RNAi, and an RNAi screen of the F-box genes identified 19 genes that recapitulated aspects of cullin-1 RNAi, including ones that in mammals are involved in stem cell regulation and cancer biology. Our data provides evidence that CRLs play discrete roles in regenerative processes and provide a platform to investigate how CRLs regulate stem cells in vivo.
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Affiliation(s)
- Nicholas S Strand
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - John M Allen
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Mahjoobah Ghulam
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Matthew R Taylor
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Roma K Munday
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Melissa Carrillo
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Artem Movsesyan
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Ricardo M Zayas
- Department of Biology, San Diego State University, San Diego, CA 92182, USA.
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11
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Seugnet L, Dissel S, Thimgan M, Cao L, Shaw PJ. Identification of Genes that Maintain Behavioral and Structural Plasticity during Sleep Loss. Front Neural Circuits 2017; 11:79. [PMID: 29109678 PMCID: PMC5660066 DOI: 10.3389/fncir.2017.00079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/05/2017] [Indexed: 11/23/2022] Open
Abstract
Although patients with primary insomnia experience sleep disruption, they are able to maintain normal performance on a variety of cognitive tasks. This observation suggests that insomnia may be a condition where predisposing factors simultaneously increase the risk for insomnia and also mitigate against the deleterious consequences of waking. To gain insight into processes that might regulate sleep and buffer neuronal circuits during sleep loss, we manipulated three genes, fat facet (faf), highwire (hiw) and the GABA receptor Resistance to dieldrin (Rdl), that were differentially modulated in a Drosophila model of insomnia. Our results indicate that increasing faf and decreasing hiw or Rdl within wake-promoting large ventral lateral clock neurons (lLNvs) induces sleep loss. As expected, sleep loss induced by decreasing hiw in the lLNvs results in deficits in short-term memory and increases of synaptic growth. However, sleep loss induced by knocking down Rdl in the lLNvs protects flies from sleep-loss induced deficits in short-term memory and increases in synaptic markers. Surprisingly, decreasing hiw and Rdl within the Mushroom Bodies (MBs) protects against the negative effects of sleep deprivation (SD) as indicated by the absence of a subsequent homeostatic response, or deficits in short-term memory. Together these results indicate that specific genes are able to disrupt sleep and protect against the negative consequences of waking in a circuit dependent manner.
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Affiliation(s)
- Laurent Seugnet
- Centre de Recherche en Neurosciences de Lyon, U1028/UMR 5292, Team WAKING, Université Claude Bernard Lyon 1, INSERM U1028, CNRS UMR 5292, Lyon, France
| | - Stephane Dissel
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, United States
| | - Matthew Thimgan
- Department of Biological Sciences, Missouri University of Science and Technology, Rolla, MO, United States
| | - Lijuan Cao
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, United States
| | - Paul J Shaw
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, United States
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12
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Abstract
The morphology and the connectivity of neuronal structures formed during early development must be actively maintained as the brain matures. Although impaired axon stability is associated with the progression of various neurological diseases, relatively little is known about the factors controlling this process. We identified Brain tumor (Brat), a conserved member of the TRIM-NHL family of proteins, as a new regulator of axon maintenance in Drosophila CNS. Brat function is dispensable for the initial growth of Mushroom Body axons, but is required for the stabilization of axon bundles. We found that Brat represses the translation of src64B, an upstream regulator of a conserved Rho-dependent pathway previously shown to promote axon retraction. Furthermore, brat phenotypes are phenocopied by src64B overexpression, and partially suppressed by reducing the levels of src64B or components of the Rho pathway, suggesting that brat promotes axon maintenance by downregulating the levels of Src64B. Finally, Brat regulates brain connectivity via its NHL domain, but independently of its previously described partners Nanos, Pumilio, and d4EHP. Thus, our results uncover a novel post-transcriptional regulatory mechanism that controls the maintenance of neuronal architecture by tuning the levels of a conserved rho-dependent signaling pathway.
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Mencacci N, Rubio-Agusti I, Zdebik A, Asmus F, Ludtmann M, Ryten M, Plagnol V, Hauser AK, Bandres-Ciga S, Bettencourt C, Forabosco P, Hughes D, Soutar M, Peall K, Morris H, Trabzuni D, Tekman M, Stanescu H, Kleta R, Carecchio M, Zorzi G, Nardocci N, Garavaglia B, Lohmann E, Weissbach A, Klein C, Hardy J, Pittman A, Foltynie T, Abramov A, Gasser T, Bhatia K, Wood N. A missense mutation in KCTD17 causes autosomal dominant myoclonus-dystonia. Am J Hum Genet 2015; 96:938-47. [PMID: 25983243 DOI: 10.1016/j.ajhg.2015.04.008] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/13/2015] [Indexed: 12/25/2022] Open
Abstract
Myoclonus-dystonia (M-D) is a rare movement disorder characterized by a combination of non-epileptic myoclonic jerks and dystonia. SGCE mutations represent a major cause for familial M-D being responsible for 30%-50% of cases. After excluding SGCE mutations, we identified through a combination of linkage analysis and whole-exome sequencing KCTD17 c.434 G>A p.(Arg145His) as the only segregating variant in a dominant British pedigree with seven subjects affected by M-D. A subsequent screening in a cohort of M-D cases without mutations in SGCE revealed the same KCTD17 variant in a German family. The clinical presentation of the KCTD17-mutated cases was distinct from the phenotype usually observed in M-D due to SGCE mutations. All cases initially presented with mild myoclonus affecting the upper limbs. Dystonia showed a progressive course, with increasing severity of symptoms and spreading from the cranio-cervical region to other sites. KCTD17 is abundantly expressed in all brain regions with the highest expression in the putamen. Weighted gene co-expression network analysis, based on mRNA expression profile of brain samples from neuropathologically healthy individuals, showed that KCTD17 is part of a putamen gene network, which is significantly enriched for dystonia genes. Functional annotation of the network showed an over-representation of genes involved in post-synaptic dopaminergic transmission. Functional studies in mutation bearing fibroblasts demonstrated abnormalities in endoplasmic reticulum-dependent calcium signaling. In conclusion, we demonstrate that the KCTD17 c.434 G>A p.(Arg145His) mutation causes autosomal dominant M-D. Further functional studies are warranted to further characterize the nature of KCTD17 contribution to the molecular pathogenesis of M-D.
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Scudder SL, Patrick GN. Synaptic structure and function are altered by the neddylation inhibitor MLN4924. Mol Cell Neurosci 2015; 65:52-7. [PMID: 25701678 DOI: 10.1016/j.mcn.2015.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/26/2015] [Accepted: 02/17/2015] [Indexed: 01/01/2023] Open
Abstract
The posttranslational modification of proteins by the ubiquitin-like small molecule NEDD8 has previously been shown to be vital in a number of cell signaling pathways. In particular, conjugation of NEDD8 (neddylation) serves to regulate protein ubiquitination through modifications to E3 ubiquitin ligases. Despite the prevalence of NEDD8 in neurons, very little work has been done to characterize the role of this modifier in these cells. Here, we use the recently developed NEDD8 Activating Enzyme (NAE) inhibitor MLN4924 and report evidence of a role for NEDD8 in regulating mammalian excitatory synapses. Application of this drug to dissociated rat hippocampal neurons caused reductions in synaptic strength, surface glutamate receptor levels, dendritic spine width, and spine density, suggesting that neddylation is involved in the maintenance of synapses.
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Affiliation(s)
- Samantha L Scudder
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, United States.
| | - Gentry N Patrick
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, United States.
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Yammine M, Saade M, Chauvet S, Nguyen C. Spatial gene's (Tbata) implication in neurite outgrowth and dendrite patterning in hippocampal neurons. Mol Cell Neurosci 2013; 59:1-9. [PMID: 24361585 DOI: 10.1016/j.mcn.2013.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 12/04/2013] [Accepted: 12/12/2013] [Indexed: 01/12/2023] Open
Abstract
The unique architecture of neurons requires the establishment and maintenance of polarity, which relies in part on microtubule-based kinesin motor transport to deliver essential cargo into axons and dendrites. In developing neurons, kinesin trafficking is essential for delivering organelles and molecules that are crucial for elongation and guidance of the growing axonal and dendritic termini. In mature neurons, kinesin cargo delivery is essential for neuron dynamic physiological functions which are critical in brain development. In this work, we followed Spatial (Tbata) gene expression during primary hippocampal neuron development and showed that it is highly expressed during dendrite formation. Spatial protein exhibits a somatodendritic distribution and we show that the kinesin motor Kif17, among other dendrite specific kinesins, is crucial for Spatial localization to dendrites of hippocampal neurons. Furthermore, Spatial down regulation in primary hippocampal cells revealed a role for Spatial in maintaining neurons' polarity by ensuring proper neurite outgrowth. This polarity is specified by intrinsic and extracellular signals that allow neurons to determine axon and dendrite fate during development. Neurotrophic factors, such as the Nerve Growth Factor (NGF), are candidate extracellular polarity-regulating cues which are proposed to accelerate neuronal polarization by enhancing dendrite growth. Here, we show that NGF treatment increases Spatial expression in hippocampal neurons. Altogether, these data suggest that Spatial, in response to NGF and through its transport by Kif17, is crucial for neuronal polarization and can be a key regulator of neurite outgrowth.
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Affiliation(s)
- Miriam Yammine
- Aix-Marseille Université, Inserm UMR 1090, TAGC, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France
| | - Murielle Saade
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Cientific de Barcelona, C/Baldiri i Reixac, Barcelona, Spain
| | - Sophie Chauvet
- Aix-Marseille Université, CNRS UMR 7288, IBDM, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France
| | - Catherine Nguyen
- Aix-Marseille Université, Inserm UMR 1090, TAGC, Campus de Luminy Case 908, 13288 Marseille Cedex 9, France.
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Pfeiffenberger C, Allada R. Cul3 and the BTB adaptor insomniac are key regulators of sleep homeostasis and a dopamine arousal pathway in Drosophila. PLoS Genet 2012; 8:e1003003. [PMID: 23055946 PMCID: PMC3464197 DOI: 10.1371/journal.pgen.1003003] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 08/15/2012] [Indexed: 12/21/2022] Open
Abstract
Sleep is homeostatically regulated, such that sleep drive reflects the duration of prior wakefulness. However, despite the discovery of genes important for sleep, a coherent molecular model for sleep homeostasis has yet to emerge. To better understand the function and regulation of sleep, we employed a reverse-genetics approach in Drosophila. An insertion in the BTB domain protein CG32810/insomniac (inc) exhibited one of the strongest baseline sleep phenotypes thus far observed, a ∼10 h sleep reduction. Importantly, this is coupled to a reduced homeostatic response to sleep deprivation, consistent with a disrupted sleep homeostat. Knockdown of the INC-interacting protein, the E3 ubiquitin ligase Cul3, results in reduced sleep duration, consolidation, and homeostasis, suggesting an important role for protein turnover in mediating INC effects. Interestingly, inc and Cul3 expression in post-mitotic neurons during development contributes to their adult sleep functions. Similar to flies with increased dopaminergic signaling, loss of inc and Cul3 result in hyper-arousability to a mechanical stimulus in adult flies. Furthermore, the inc sleep duration phenotype can be rescued by pharmacological inhibition of tyrosine hydroxylase, the rate-limiting enzyme for dopamine biosynthesis. Taken together, these results establish inc and Cul3 as important new players in setting the sleep homeostat and a dopaminergic arousal pathway in Drosophila. Sleep is an essential behavior that encompasses roughly a third of our lives; however, the underlying function remains a mystery. The fruit fly has emerged as an important model system for understanding sleep behavior, exhibiting several behavioral and genetic similarities with mammalian sleep, including consolidated immobility, an elevation of arousal threshold to a range of stimuli, homeostatic drive, and manipulation by proven stimulants and sedatives. We tested disruptions of candidate sleep genes and identified a gene called insomniac that exhibits one of the strongest and most robust sleep phenotypes to date, including a suppressed homeostatic response to sleep deprivation. We find similar phenotypes for a gene previously shown to interact with inc and a known regulator of protein degradation, Cul3, linking sleep homeostasis to protein turnover. Importantly, we find that insomniac functions in a known arousal system in the brain, as defined by the neurotransmitter dopamine. This work provides an important insight into the genetic basis of sleep homeostasis with the discovery of a new molecular component of a dopaminergic arousal pathway. Given the conservation of fly and mammalian systems, these studies may lead to new insights into the molecules that mediate sleep homeostasis and arousal in humans.
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Affiliation(s)
| | - Ravi Allada
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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17
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CULLIN-3 controls TIMELESS oscillations in the Drosophila circadian clock. PLoS Biol 2012; 10:e1001367. [PMID: 22879814 PMCID: PMC3413713 DOI: 10.1371/journal.pbio.1001367] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 06/14/2012] [Indexed: 12/17/2022] Open
Abstract
The ubiquitin ligases CUL-3 and SLMB collaborate to regulate the Drosophila circadian clock by controlling TIMELESS oscillations. Eukaryotic circadian clocks rely on transcriptional feedback loops. In Drosophila, the PERIOD (PER) and TIMELESS (TIM) proteins accumulate during the night, inhibit the activity of the CLOCK (CLK)/CYCLE (CYC) transcriptional complex, and are degraded in the early morning. The control of PER and TIM oscillations largely depends on post-translational mechanisms. They involve both light-dependent and light-independent pathways that rely on the phosphorylation, ubiquitination, and proteasomal degradation of the clock proteins. SLMB, which is part of a CULLIN-1-based E3 ubiquitin ligase complex, is required for the circadian degradation of phosphorylated PER. We show here that CULLIN-3 (CUL-3) is required for the circadian control of PER and TIM oscillations. Expression of either Cul-3 RNAi or dominant negative forms of CUL-3 in the clock neurons alters locomotor behavior and dampens PER and TIM oscillations in light-dark cycles. In constant conditions, CUL-3 deregulation induces behavioral arrhythmicity and rapidly abolishes TIM cycling, with slower effects on PER. CUL-3 affects TIM accumulation more strongly in the absence of PER and forms protein complexes with hypo-phosphorylated TIM. In contrast, SLMB affects TIM more strongly in the presence of PER and preferentially associates with phosphorylated TIM. CUL-3 and SLMB show additive effects on TIM and PER, suggesting different roles for the two ubiquitination complexes on PER and TIM cycling. This work thus shows that CUL-3 is a new component of the Drosophila clock, which plays an important role in the control of TIM oscillations. Circadian clocks adjust the physiology and behavior of organisms to the day/night cycle and rely on molecular feedback loops that generate daily oscillations of transcription. In the Drosophila fruit fly, the PERIOD (PER) and TIMELESS (TIM) proteins coordinate the clock–they accumulate during the night, form a complex, and repress their own gene expression in the early morning. The temporal control of this oscillation involves the phosphorylation, ubiquitination, and proteasomal degradation of the PER and TIM proteins. The SUPERNUMERARY LIMBS (SLMB) ubiquitin ligase is known to play a key role in controlling the degradation of phosphorylated PER and TIM. In this study we investigated the role of another ubiquitin ligase, CULLIN-3 (CUL-3). We found that inhibition of CUL-3 activity results in the abolition of rest/activity rhythms in flies and flattens the PER and TIM oscillations. CUL-3 physically interacts and forms a complex with a lowphosphorylated version of TIM in the absence of PER, thereby allowing its accumulation during the night. In contrast, when PER is present SLMB preferentially interacts with phosphorylated TIM, favoring its degradation. The results suggest that CUL-3 and SLMB share the work to control the oscillations of the PER and TIM proteins during the day/night cycle.
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Stavropoulos N, Young MW. insomniac and Cullin-3 regulate sleep and wakefulness in Drosophila. Neuron 2012; 72:964-76. [PMID: 22196332 DOI: 10.1016/j.neuron.2011.12.003] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2011] [Indexed: 12/15/2022]
Abstract
In a forward genetic screen in Drosophila, we have isolated insomniac, a mutant that severely reduces the duration and consolidation of sleep. Anatomically restricted genetic manipulations indicate that insomniac functions within neurons to regulate sleep. insomniac expression does not oscillate in a circadian manner, and conversely, the circadian clock is intact in insomniac mutants, suggesting that insomniac regulates sleep by pathways distinct from the circadian clock. The protein encoded by insomniac is a member of the BTB/POZ superfamily, which includes many proteins that function as adaptors for the Cullin-3 (Cul3) ubiquitin ligase complex. We show that Insomniac can physically associate with Cul3, and that reduction of Cul3 activity in neurons recapitulates the insomniac phenotype. The extensive evolutionary conservation of insomniac and Cul3 suggests that protein degradation pathways may have a general role in governing the sleep and wakefulness of animals.
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Affiliation(s)
- Nicholas Stavropoulos
- Laboratory of Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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19
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Abstract
Cullin proteins are molecular scaffolds that have crucial roles in the post-translational modification of cellular proteins involving ubiquitin. The mammalian cullin protein family comprises eight members (CUL1 to CUL7 and PARC), which are characterized by a cullin homology domain. CUL1 to CUL7 assemble multi-subunit Cullin-RING E3 ubiquitin ligase (CRL) complexes, the largest family of E3 ligases with more than 200 members. Although CUL7 and PARC are present only in chordates, other members of the cullin protein family are found in Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana and yeast. A cullin protein tethers both a substrate-targeting unit, often through an adaptor protein, and the RING finger component in a CRL. The cullin-organized CRL thus positions a substrate close to the RING-bound E2 ubiquitin-conjugating enzyme, which catalyzes the transfer of ubiquitin to the substrate. In addition, conjugation of cullins with the ubiquitin-like molecule Nedd8 modulates activation of the corresponding CRL complex, probably through conformational regulation of the interactions between cullin's carboxy-terminal tail and CRL's RING subunit. Genetic studies in several model organisms have helped to unravel a multitude of physiological functions associated with cullin proteins and their respective CRLs. CRLs target numerous substrates and thus have an impact on a range of biological processes, including cell growth, development, signal transduction, transcriptional control, genomic integrity and tumor suppression. Moreover, mutations in CUL7 and CUL4B genes have been linked to hereditary human diseases.
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Affiliation(s)
- Antonio Sarikas
- Institute of Pharmacology and Toxicology, Technische Universität München, 80802 Munich, Germany.
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21
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Leiss F, Groh C, Butcher NJ, Meinertzhagen IA, Tavosanis G. Synaptic organization in the adult Drosophila mushroom body calyx. J Comp Neurol 2010; 517:808-24. [PMID: 19844895 DOI: 10.1002/cne.22184] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Insect mushroom bodies are critical for olfactory associative learning. We have carried out an extensive quantitative description of the synaptic organization of the calyx of adult Drosophila melanogaster, the main olfactory input region of the mushroom body. By using high-resolution confocal microscopy, electron microscopy-based three-dimensional reconstructions, and genetic labeling of the neuronal populations contributing to the calyx, we resolved the precise connections between large cholinergic boutons of antennal lobe projection neurons and the dendrites of Kenyon cells, the mushroom body intrinsic neurons. Throughout the calyx, these elements constitute synaptic complexes called microglomeruli. By single-cell labeling, we show that each Kenyon cell's claw-like dendritic specialization is highly enriched in filamentous actin, suggesting that this might be a site of plastic reorganization. In fact, Lim kinase (LimK) overexpression in the Kenyon cells modifies the shape of the microglomeruli. Confocal and electron microscopy indicate that each Kenyon cell claw enwraps a single bouton of a projection neuron. Each bouton is contacted by a number of such claw-like specializations as well as profiles of gamma-aminobutyric acid-positive neurons. The dendrites of distinct populations of Kenyon cells involved in different types of memory are partially segregated within the calyx and contribute to different subsets of microglomeruli. Our analysis suggests, though, that projection neuron boutons can contact more than one type of Kenyon cell. These findings represent an important basis for the functional analysis of the olfactory pathway, including the formation of associative olfactory memories.
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Affiliation(s)
- Florian Leiss
- Department of Molecular Neurobiology, Max Planck Institute of Neurobiology, 82152 Munich, Germany
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Fujiyama-Nakamura S, Ito S, Sawatsubashi S, Yamauchi Y, Suzuki E, Tanabe M, Kimura S, Murata T, Isobe T, ichi Takeyama K, Kato S. BTB protein, dKLHL18/CG3571, serves as an adaptor subunit for a dCul3 ubiquitin ligase complex. Genes Cells 2009; 14:965-73. [DOI: 10.1111/j.1365-2443.2009.01323.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Aso Y, Grübel K, Busch S, Friedrich AB, Siwanowicz I, Tanimoto H. The mushroom body of adult Drosophila characterized by GAL4 drivers. J Neurogenet 2009; 23:156-72. [PMID: 19140035 DOI: 10.1080/01677060802471718] [Citation(s) in RCA: 271] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The mushroom body is required for a variety of behaviors of Drosophila melanogaster. Different types of intrinsic and extrinsic mushroom body neurons might underlie its functional diversity. There have been many GAL4 driver lines identified that prominently label the mushroom body intrinsic neurons, which are known as "Kenyon cells." Under one constant experimental condition, we analyzed and compared the the expression patterns of 25 GAL4 drivers labeling the mushroom body. As an internet resource, we established a digital catalog indexing representative confocal data of them. Further more, we counted the number of GAL4-positive Kenyon cells in each line. We found that approximately 2,000 Kenyon cells can be genetically labeled in total. Three major Kenyon cell subtypes, the gamma, alpha'/beta', and alpha/beta neurons, respectively, contribute to 33, 18, and 49% of 2,000 Kenyon cells. Taken together, this study lays groundwork for functional dissection of the mushroom body.
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Affiliation(s)
- Yoshinori Aso
- Max-Planck-Institut für Neurobiologie, Martinsried, Germany
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A targeted gain-of-function screen identifies genes affecting salivary gland morphogenesis/tubulogenesis in Drosophila. Genetics 2008; 181:543-65. [PMID: 19064711 DOI: 10.1534/genetics.108.094052] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During development individual cells in tissues undergo complex cell-shape changes to drive the morphogenetic movements required to form tissues. Cell shape is determined by the cytoskeleton and cell-shape changes critically depend on a tight spatial and temporal control of cytoskeletal behavior. We have used the formation of the salivary glands in the Drosophila embryo, a process of tubulogenesis, as an assay for identifying factors that impinge on cell shape and the cytoskeleton. To this end we have performed a gain-of-function screen in the salivary glands, using a collection of fly lines carrying EP-element insertions that allow the overexpression of downstream-located genes using the UAS-Gal4 system. We used a salivary-gland-specific fork head-Gal4 line to restrict expression to the salivary glands, in combination with reporters of cell shape and the cytoskeleton. We identified a number of genes known to affect salivary gland formation, confirming the effectiveness of the screen. In addition, we found many genes not implicated previously in this process, some having known functions in other tissues. We report the initial characterization of a subset of genes, including chickadee, rhomboid1, egalitarian, bitesize, and capricious, through comparison of gain- and loss-of-function phenotypes.
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25
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Yang JSJ, Bai JM, Lee T. Dynein-dynactin complex is essential for dendritic restriction of TM1-containing Drosophila Dscam. PLoS One 2008; 3:e3504. [PMID: 18946501 PMCID: PMC2566808 DOI: 10.1371/journal.pone.0003504] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 09/29/2008] [Indexed: 01/14/2023] Open
Abstract
Background Many membrane proteins, including Drosophila Dscam, are enriched in dendrites or axons within neurons. However, little is known about how the differential distribution is established and maintained. Methodology/Principal Findings Here we investigated the mechanisms underlying the dendritic targeting of Dscam[TM1]. Through forward genetic mosaic screens and by silencing specific genes via targeted RNAi, we found that several genes, encoding various components of the dynein-dynactin complex, are required for restricting Dscam[TM1] to the mushroom body dendrites. In contrast, compromising dynein/dynactin function did not affect dendritic targeting of two other dendritic markers, Nod and Rdl. Tracing newly synthesized Dscam[TM1] further revealed that compromising dynein/dynactin function did not affect the initial dendritic targeting of Dscam[TM1], but disrupted the maintenance of its restriction to dendrites. Conclusions/Significance The results of this study suggest multiple mechanisms of dendritic protein targeting. Notably, dynein-dynactin plays a role in excluding dendritic Dscam, but not Rdl, from axons by retrograde transport.
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Affiliation(s)
- Jacob Shun-Jen Yang
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jia-Min Bai
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Tzumin Lee
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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26
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Shi L, Lin S, Grinberg Y, Beck Y, Grozinger CM, Robinson GE, Lee T. Roles of Drosophila Kruppel-homolog 1 in neuronal morphogenesis. Dev Neurobiol 2007; 67:1614-26. [PMID: 17562531 DOI: 10.1002/dneu.20537] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The molecular mechanisms underlying remodeling of neural networks remain largely unknown. In Drosophila, widespread neural remodeling occurs during metamorphosis, and is regulated by ecdysone. Kruppel-homolog 1 (Kr-h1) is a zinc finger transcription factor known to play a role in orchestrating ecdysone-regulated transcriptional pathways and, furthermore, implicated in governing axon morphogenesis. Interestingly, in honey bee workers, neural expression of the Apis mellifera homolog of Kr-h1 is enhanced during their transition to foraging behavior when there is increased neurite outgrowth, branching, and synapse formation. Here, we assessed the role(s) of KR-H1 in Drosophila neuronal remodeling and morphology. We characterized the effect of Kr-h1 expression on neuronal morphology through Drosophila larval, pupal, and adult stages. Increased expression of Kr-h1 led to reduced branching in individual neurons and gross morphological changes in the mushroom bodies (MBs), while knocking down Kr-h1 did not produce any obvious changes in neural morphology. Drosophila Kr-h1 is normally expressed when MB neurons do not undergo active morphogenesis, suggesting that it may play a role in inhibiting morphogenesis. Further, loss of endogenous KR-H1 enhanced the neuronal morphogenesis that is otherwise delayed due to defective TGF-beta signaling. However, loss of KR-H1 alone did not affect neuronal morphogenesis. In addition, Kr-h1 expression remains strongly linked to ecdysone-regulated pathways: Kr-h1 expression is regulated by usp, which dimerizes to the ecdysone receptor, and Kr-h1 expression is essential for proper patterning of the ecdysone receptor isoforms in the late larval central nervous system. Thus, although KR-H1 has a potential for modulating neuronal morphogenesis, it appears physiologically involved in coordinating general ecdysone signaling.
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Affiliation(s)
- Lei Shi
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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27
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Yu HH, Lee T. Neuronal temporal identity in post-embryonic Drosophila brain. Trends Neurosci 2007; 30:520-6. [PMID: 17825435 DOI: 10.1016/j.tins.2007.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 07/18/2007] [Accepted: 07/18/2007] [Indexed: 11/25/2022]
Abstract
Understanding how a vast number of neuron types derive from a limited number of neural progenitors remains a major challenge in developmental neurobiology. In the post-embryonic Drosophila brain, specific neuron types derive from specific progenitors at specific times. This suggests involvement of time-dependent cell fate determinants acting as 'temporal codes' along with lineage cues to specify neuronal cell fates. Interestingly, such temporal codes might be provided not only by several regulators acting in sequence, but also by the differential protein levels of the BTB-zinc finger nuclear protein Chinmo. Identifying temporal codes and determining their origins should allow us to elucidate how neuronal diversification occurs through protracted neurogenesis.
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Affiliation(s)
- Hung-Hsiang Yu
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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28
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McEvoy JD, Kossatz U, Malek N, Singer JD. Constitutive turnover of cyclin E by Cul3 maintains quiescence. Mol Cell Biol 2007; 27:3651-66. [PMID: 17339333 PMCID: PMC1899986 DOI: 10.1128/mcb.00720-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two distinct pathways for the degradation of mammalian cyclin E have previously been described. One pathway is induced by cyclin E phosphorylation and is dependent on the Cul1/Fbw7-based E3 ligase. The other pathway is dependent on the Cul3-based E3 ligase, but the mechanistic details of this pathway have yet to be elucidated. To establish the role of Cul3 in the degradation of cyclin E in vivo, we created a conditional knockout of the Cul3 gene in mice. Interestingly, the biallelic loss of Cul3 in primary fibroblasts derived from these mice results in increased cyclin E expression and reduced cell viability, paralleling the loss of Cul3 protein expression. Cell cycle analysis of viable, Cul3 hypomorphic cells shows that decreasing the levels of Cul3 increases both cyclin E protein levels and the number of cells in S phase. In order to examine the role of Cul3 in an in vivo setting, we determined the effect of deletion of the Cul3 gene in liver. This gene deletion resulted in a dramatic increase in cyclin E levels as well as an increase in cell size and ploidy. The results we report here show that the constitutive degradation pathway for cyclin E that is regulated by the Cul3-based E3 ligase is essential to maintain quiescence in mammalian cells.
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Affiliation(s)
- Justina D McEvoy
- Department of Molecular Biology, Cell Biology and Biochemistry and Center for Genomics and Proteomics, Brown University, 70 Ship Street, Box G-E337, Providence, RI 02903, USA
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29
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Abstract
Cullins are members of a family of scaffold proteins that assemble multisubunit ubiquitin ligase complexes to confer substrate specificity for the ubiquitination pathway. Cullin3 (Cul3) forms a catalytically inactive BTB-Cul3-Rbx1 (BCR) ubiquitin ligase, which becomes functional upon covalent attachment of the ubiquitin homologue neural-precursor-cell-expressed and developmentally down regulated 8 (Nedd8) near the C terminus of Cul3. Current models suggest that Nedd8 activates cullin complexes by providing a recognition site for a ubiquitin-conjugating enzyme. Based on the following evidence, we propose that Nedd8 activates the BCR ubiquitin ligase by mediating the dimerization of Cul3. First, Cul3 is found as a neddylated heterodimer bound to a BTB domain-containing protein in vivo. Second, the formation of a Cul3 heterodimer is mediated by a Nedd8 molecule, which covalently attaches itself to one Cul3 molecule and binds to the winged-helix B domain at the C terminus of the second Cul3 molecule. Third, complementation experiments revealed that coexpression of two distinct nonfunctional Cul3 mutants can rescue the ubiquitin ligase function of the BCR complex. Likewise, a substrate of the BCR complex binds heterodimeric Cul3, suggesting that the Cul3 complex is active as a dimer. These findings not only provide insight into the architecture of the active BCR complex but also suggest assembly as a regulatory mechanism for activation of all cullin-based ubiquitin ligases.
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Affiliation(s)
- Wananit Wimuttisuk
- Department of Molecular Biology, Cell Biology and Biochemistry and Center for Genomics and Proteomics, Brown University, Providence, RI 02903
| | - Jeffrey D. Singer
- Department of Molecular Biology, Cell Biology and Biochemistry and Center for Genomics and Proteomics, Brown University, Providence, RI 02903
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Zhu S, Lin S, Kao CF, Awasaki T, Chiang AS, Lee T. Gradients of the Drosophila Chinmo BTB-Zinc Finger Protein Govern Neuronal Temporal Identity. Cell 2006; 127:409-22. [PMID: 17055440 DOI: 10.1016/j.cell.2006.08.045] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 06/08/2006] [Accepted: 08/15/2006] [Indexed: 11/26/2022]
Abstract
Many neural progenitors, including Drosophila mushroom body (MB) and projection neuron (PN) neuroblasts, sequentially give rise to different subtypes of neurons throughout development. We identified a novel BTB-zinc finger protein, named Chinmo (Chronologically inappropriate morphogenesis), that governs neuronal temporal identity during postembryonic development of the Drosophila brain. In both MB and PN lineages, loss of Chinmo autonomously causes early-born neurons to adopt the fates of late-born neurons from the same lineages. Interestingly, primarily due to a posttranscriptional control, MB neurons born at early developmental stages contain more abundant Chinmo than their later-born siblings. Further, the temporal identity of MB progeny can be transformed toward earlier or later fates by reducing or increasing Chinmo levels, respectively. Taken together, we suggest that a temporal gradient of Chinmo (Chinmo(high) --> Chinmo(low)) helps specify distinct birth order-dependent cell fates in an extended neuronal lineage.
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Affiliation(s)
- Sijun Zhu
- Department of Cell and Developmental Biology, University of Illinois, Urbana, 61801, USA
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31
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Kim HJ, Kim SH, Shim SO, Park E, Kim C, Kim K, Tanouye MA, Yim J. Drosophila homolog of APP-BP1 (dAPP-BP1) interacts antagonistically with APPL during Drosophila development. Cell Death Differ 2006; 14:103-15. [PMID: 16628230 DOI: 10.1038/sj.cdd.4401935] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
beta-Amyloid precursor protein binding protein 1 (APP-BP1) was previously identified based on its binding to the carboxyl terminal of beta-amyloid precursor protein. In this report, we have discovered that a mutation of dAPP-BP1 (Drosophila ortholog of APP-BP1) hinders tissue development, causes apoptosis in imaginal disc cells, and blocks the NEDD8 conjugation pathway. We show that dAPP-BP1 specifically binds the intracellular domain of APP-like protein (APPL). The dAPP-BP1 mutation partially suppresses the abnormal macrochaete phenotype of Appl(d), while overexpression of dAPP-BP1 causes abnormal macrochaetes. When APPL is overexpressed, the normal bristle pattern in the fly thorax is disturbed and apoptosis is induced in wing imaginal discs. APPL overexpression phenotypes are enhanced by reducing the level of dAPP-BP1. APPL overexpression is shown to inhibit the NEDD8 conjugation pathway. APPL-induced apoptosis is rescued by overexpression of dAPP-BP1. Our data suggest that APPL and dAPP-BP1 interact antagonistically during Drosophila development.
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Affiliation(s)
- H-J Kim
- School of Biological Science, Seoul National University, Seoul, Korea
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32
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Lo SC, Hannink M. CAND1-mediated substrate adaptor recycling is required for efficient repression of Nrf2 by Keap1. Mol Cell Biol 2006; 26:1235-44. [PMID: 16449638 PMCID: PMC1367193 DOI: 10.1128/mcb.26.4.1235-1244.2006] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The bZIP transcription factor Nrf2 controls a genetic program that protects cells from oxidative damage and maintains cellular redox homeostasis. Keap1, a BTB-Kelch protein, is the major upstream regulator of Nrf2. Keap1 functions as a substrate adaptor protein for a Cul3-dependent E3 ubiquitin ligase complex to repress steady-state levels of Nrf2 and Nrf2-dependent transcription. Cullin-dependent ubiquitin ligase complexes have been proposed to undergo dynamic cycles of assembly and disassembly that enable substrate adaptor exchange or recycling. In this report, we have characterized the importance of substrate adaptor recycling for regulation of Keap1-mediated repression of Nrf2. Association of Keap1 with Cul3 was decreased by ectopic expression of CAND1 and was increased by small interfering RNA (siRNA)-mediated knockdown of CAND1. However, both ectopic overexpression and siRNA-mediated knockdown of CAND1 decreased the ability of Keap1 to target Nrf2 for ubiquitin-dependent degradation, resulting in stabilization of Nrf2 and activation of Nrf2-dependent gene expression. Neddylation of Cul3 on Lys 712 is required for Keap1-dependent ubiquitination of Nrf2 in vivo. However, the K712R mutant Cul3 molecule, which is not neddylated, can still assemble with Keap1 into a functional ubiquitin ligase complex in vitro. These results provide support for a model in which substrate adaptor recycling is required for efficient substrate ubiquitination by cullin-dependent E3 ubiquitin ligase complexes.
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Affiliation(s)
- Shih-Ching Lo
- Department of Biochemistry, Life Science Center, M121 Medical Sciences Building, University of Missouri-Columbia, Columbia, MO 65212, USA
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33
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Landgraf M, Evers JF. Control of dendritic diversity. Curr Opin Cell Biol 2005; 17:690-6. [PMID: 16226445 DOI: 10.1016/j.ceb.2005.09.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Accepted: 09/29/2005] [Indexed: 11/16/2022]
Abstract
The dendritic trees of different neuronal types display an astonishing diversity in structure and function. How this diversity is generated remains incompletely understood. However, recent studies have revealed some of the underlying mechanisms by which intrinsic programs of cell-type specification and extrinsic factors exert their effects on the dendritic cytoskeleton to regulate patterns of growth and branching.
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Affiliation(s)
- Matthias Landgraf
- University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, UK.
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