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McMann E, Gorski SM. Last but not least: emerging roles of the autophagy-related protein ATG4D. Autophagy 2024; 20:1916-1927. [PMID: 38920354 PMCID: PMC11346562 DOI: 10.1080/15548627.2024.2369436] [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: 11/27/2023] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 06/27/2024] Open
Abstract
The evolutionarily conserved ATG4 cysteine proteases regulate macroautophagy/autophagy through the priming and deconjugation of the Atg8-family proteins. In mammals there are four ATG4 family members (ATG4A, ATG4B, ATG4C, ATG4D) but ATG4D has been relatively understudied. Heightened interest in ATG4D has been stimulated by recent links to human disease. Notably, genetic variations in human ATG4D were implicated in a heritable neurodevelopmental disorder. Genetic analyses in dogs, along with loss-of-function zebrafish and mouse models, further support a neuroprotective role for ATG4D. Here we discuss the evidence connecting ATG4D to neurological diseases and other pathologies and summarize its roles in both autophagy-dependent and autophagy-independent cellular processes.Abbrevation: ATG: autophagy related; BafA1: bafilomycin A1; BCL2: BCL2 apoptosis regulator; BH3: BCL2 homology region 3; CASP3: caspase 3; EV: extracellular vesicle; GABA: gamma aminobutyric acid; GABARAP: GABA type A receptor-associated protein; GABARAPL1: GABA type A receptor associated protein like 1; GABARAPL2: GABA type A receptor associated protein like 2; GFP: green fluorescent protein; LIR: LC3-interacting region; MAP1LC3: microtubule associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; MYC: MYC proto-oncogene, bHLH transcription factor; PE: phosphatidylethanolamine; PS: phosphatidylserine; QKO: quadruple knockout; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel; SQSTM1: sequestosome 1.
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Affiliation(s)
- Emily McMann
- Canada’s Michael Smith Genome Sciences Centre at BC Cancer, Vancouver, British Columbia, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sharon M. Gorski
- Canada’s Michael Smith Genome Sciences Centre at BC Cancer, Vancouver, British Columbia, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
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2
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Üffing A, Weiergräber OH, Schwarten M, Hoffmann S, Willbold D. GABARAP interacts with EGFR - supporting the unique role of this hAtg8 protein during receptor trafficking. FEBS Lett 2024. [PMID: 39160442 DOI: 10.1002/1873-3468.14997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/02/2024] [Accepted: 07/24/2024] [Indexed: 08/21/2024]
Abstract
The human Atg8 family member GABARAP is involved in numerous autophagy-related and -unrelated processes. We recently observed that specifically the deficiency of GABARAP enhances epidermal growth factor receptor (EGFR) degradation upon ligand stimulation. Here, we report on two putative LC3-interacting regions (LIRs) within EGFR, the first of which (LIR1) is selected as a GABARAP binding site in silico. Indeed, in vitro interaction studies reveal preferential binding of LIR1 to GABARAP and GABARAPL1. Our X-ray data demonstrate interaction of core LIR1 residues FLPV with both hydrophobic pockets of GABARAP suggesting canonical binding. Although LIR1 occupies the LIR docking site, GABARAP Y49 and L50 appear dispensable in this case. Our data support the hypothesis that GABARAP affects the fate of EGFR at least in part through direct binding.
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Affiliation(s)
- Alina Üffing
- Heinrich-Heine-Universität Düsseldorf, Mathematisch-Naturwissenschaftliche Fakultät, Institut für Physikalische Biologie, Düsseldorf, Germany
- Forschungszentrum Jülich, Institut für Biologische Informationsprozesse: Strukturbiochemie (IBI-7), Jülich, Germany
| | - Oliver H Weiergräber
- Heinrich-Heine-Universität Düsseldorf, Mathematisch-Naturwissenschaftliche Fakultät, Institut für Physikalische Biologie, Düsseldorf, Germany
- Forschungszentrum Jülich, Institut für Biologische Informationsprozesse: Strukturbiochemie (IBI-7), Jülich, Germany
| | - Melanie Schwarten
- Forschungszentrum Jülich, Institut für Biologische Informationsprozesse: Strukturbiochemie (IBI-7), Jülich, Germany
| | - Silke Hoffmann
- Forschungszentrum Jülich, Institut für Biologische Informationsprozesse: Strukturbiochemie (IBI-7), Jülich, Germany
| | - Dieter Willbold
- Heinrich-Heine-Universität Düsseldorf, Mathematisch-Naturwissenschaftliche Fakultät, Institut für Physikalische Biologie, Düsseldorf, Germany
- Forschungszentrum Jülich, Institut für Biologische Informationsprozesse: Strukturbiochemie (IBI-7), Jülich, Germany
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3
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Chen J, Zhao H, Liu M, Chen L. A new perspective on the autophagic and non-autophagic functions of the GABARAP protein family: a potential therapeutic target for human diseases. Mol Cell Biochem 2024; 479:1415-1441. [PMID: 37440122 DOI: 10.1007/s11010-023-04800-5] [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: 03/16/2023] [Accepted: 06/24/2023] [Indexed: 07/14/2023]
Abstract
Mammalian autophagy-related protein Atg8, including the LC3 subfamily and GABARAP subfamily. Atg8 proteins play a vital role in autophagy initiation, autophagosome formation and transport, and autophagy-lysosome fusion. GABARAP subfamily proteins (GABARAPs) share a high degree of homology with LC3 family proteins, and their unique roles are often overlooked. GABARAPs are as indispensable as LC3 in autophagy. Deletion of GABARAPs fails autophagy flux induction and autophagy lysosomal fusion, which leads to the failure of autophagy. GABARAPs are also involved in the transport of selective autophagy receptors. They are engaged in various particular autophagy processes, including mitochondrial autophagy, endoplasmic reticulum autophagy, Golgi autophagy, centrosome autophagy, and dorphagy. Furthermore, GABARAPs are closely related to the transport and delivery of the inhibitory neurotransmitter γ-GABAA and the angiotensin II AT1 receptor (AT1R), tumor growth, metastasis, and prognosis. GABARAPs also have been confirmed to be involved in various diseases, such as cancer, cardiovascular disease, and neurodegenerative diseases. In order to better understand the role and therapeutic potential of GABARAPs, this article comprehensively reviews the autophagic and non-autophagic functions of GABARAPs, as well as the research progress of the role and mechanism of GABARAPs in cancer, cardiovascular diseases and neurodegenerative diseases. It emphasizes the significance of GABARAPs in the clinical prevention and treatment of diseases, and may provide new therapeutic ideas and targets for human diseases. GABARAP and GABARAPL1 in the serum of cancer patients are positively correlated with the prognosis of patients, which can be used as a clinical biomarker, predictor and potential therapeutic target.
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Affiliation(s)
- Jiawei Chen
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Hong Zhao
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
- School of Nursing, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Meiqing Liu
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China.
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China.
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4
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Dunham TL, Wilkerson JR, Johnson RC, Huganir RL, Volk LJ. Modulation of GABA A receptor trafficking by WWC2 reveals class-specific mechanisms of synapse regulation by WWC family proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.584487. [PMID: 38559047 PMCID: PMC10979870 DOI: 10.1101/2024.03.11.584487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
WWC2 (WW and C2 domain-containing protein) is implicated in several neurological disorders, however its function in the brain has yet to be determined. Here, we demonstrate that WWC2 interacts with inhibitory but not excitatory postsynaptic scaffolds, consistent with prior proteomic identification of WWC2 as a putative component of the inhibitory postsynaptic density. Using mice lacking WWC2 expression in excitatory forebrain neurons, we show that WWC2 suppresses GABA A R incorporation into the plasma membrane and regulates HAP1 and GRIP1, which form a complex promoting GABA A R recycling to the membrane. Inhibitory synaptic transmission is dysregulated in CA1 pyramidal cells lacking WWC2. Furthermore, unlike the WWC2 homolog KIBRA (WWC1), a key regulator of AMPA receptor trafficking at excitatory synapses, deletion of WWC2 does not affect synaptic AMPAR expression. In contrast, loss of KIBRA does not affect GABA A R membrane expression. These data reveal unique, synapse class-selective functions for WWC proteins as regulators of ionotropic neurotransmitter receptors and provide insight into mechanisms regulating GABA A R membrane expression.
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Chen M, Koopmans F, Gonzalez-Lozano MA, Smit AB, Li KW. Brain Region Differences in α1- and α5-Subunit-Containing GABA A Receptor Proteomes Revealed with Affinity Purification and Blue Native PAGE Proteomics. Cells 2023; 13:14. [PMID: 38201218 PMCID: PMC10778189 DOI: 10.3390/cells13010014] [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: 11/09/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024] Open
Abstract
GABAA receptors are the major inhibitory receptors in the brain. They are hetero-pentamers with a composition of predominantly two α, two β, and one γ or δ subunit. Of the six α subunit genes, the α5 subunit displays a limited spatial expression pattern and is known to mediate both phasic and tonic inhibition. In this study, using immunoaffinity-based proteomics, we identified the α5 subunit containing receptor complexes in the hippocampus and olfactory bulb. The α1-α5 interaction was identified in both brain regions, albeit with significantly different stoichiometries. In line with this, reverse IPs using anti-α1 antibodies showed the α5-α1 co-occurrence and validated the quantitative difference. In addition, we showed that the association of Neuroligin 2 with α1-containing receptors was much higher in the olfactory bulb than in the hippocampus, which was confirmed using blue native gel electrophoresis and quantitative mass spectrometry. Finally, immunocytochemical staining revealed a co-localization of α1 and α5 subunits in the post-synaptic puncta in the hippocampus.
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Affiliation(s)
| | | | | | | | - Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands; (M.C.); (M.A.G.-L.); (A.B.S.)
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6
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Mabuchi Y, Cui X, Xie L, Kim H, Jiang T, Yapici N. Visual feedback neurons fine-tune Drosophila male courtship via GABA-mediated inhibition. Curr Biol 2023; 33:3896-3910.e7. [PMID: 37673068 PMCID: PMC10529139 DOI: 10.1016/j.cub.2023.08.034] [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: 02/09/2023] [Revised: 06/27/2023] [Accepted: 08/11/2023] [Indexed: 09/08/2023]
Abstract
Many species of animals use vision to regulate their social behaviors. However, the molecular and circuit mechanisms underlying visually guided social interactions remain largely unknown. Here, we show that the Drosophila ortholog of the human GABAA-receptor-associated protein (GABARAP) is required in a class of visual feedback neurons, lamina tangential (Lat) cells, to fine-tune male courtship. GABARAP is a ubiquitin-like protein that maintains cell-surface levels of GABAA receptors. We demonstrate that knocking down GABARAP or GABAAreceptors in Lat neurons or hyperactivating them induces male courtship toward other males. Inhibiting Lat neurons, on the other hand, delays copulation by impairing the ability of males to follow females. Remarkably, the fly GABARAP protein and its human ortholog share a strong sequence identity, and the fly GABARAP function in Lat neurons can be rescued by its human ortholog. Using in vivo two-photon imaging and optogenetics, we reveal that Lat neurons are functionally connected to neural circuits that mediate visually guided courtship pursuits in males. Our work identifies a novel physiological function for GABARAP in regulating visually guided courtship pursuits in Drosophila males. Reduced GABAA signaling has been linked to social deficits observed in the autism spectrum and bipolar disorders. The functional similarity between the human and the fly GABARAP raises the possibility of a conserved role for this gene in regulating social behaviors across insects and mammals.
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Affiliation(s)
- Yuta Mabuchi
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Xinyue Cui
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Lily Xie
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Haein Kim
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Tianxing Jiang
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Nilay Yapici
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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7
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Li C, Huang S, Peng J, Hong T, Zhou C, Tang J. 14-3-3ζ Mediates GABA AR Activation by Interacting with BIG1. Mol Neurobiol 2023; 60:1721-1732. [PMID: 36562883 DOI: 10.1007/s12035-022-03172-z] [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: 07/28/2022] [Accepted: 12/10/2022] [Indexed: 12/24/2022]
Abstract
Most fast synaptic inhibitions in the mammalian brain are mediated by GABAA receptors (GABAARs). An appropriate level of GABAAR expression at the cell surface is essential for neurodevelopment and the efficacy of GABAergic synaptic transmission. We previously reported that brefeldin A-inhibited GDP/GTP exchange factor 1 (BIG1), a binding partner of GABAARs, plays an important role in trafficking GABAARs to the cell surface. However, its regulatory mechanisms remain unknown. In the present study, we identified a new cellular protein, 14-3-3ζ, which can interact with the β subunit of GABAARs and BIG1 both in vitro and in vivo and colocalizes in the soma, dendrites, and axons of hippocampal neurons. Overexpression of 14-3-3ζ-WT increased the surface expression of BIG1 in dendrites and axons, as well as the binding of BIG1 with GABAAR. Depleted 14-3-3ζ with efficacious siRNA attenuated the interaction between BIG1 and GABAARs and resulted in significant decreases in the surface expression levels of BIG1 and GABAAR. GABAAR agonist treatment increased the expression levels of BIG1 and 14-3-3ζ on the surface, indicating that 14-3-3ζ is involved in regulating BIG1-mediated GABAAR surface expression. Depletion of BIG1 or 14-3-3ζ significantly decreased GABAAR expression at the cell surface and suppressed the GABA-gated influx of chloride ions. These data indicate that the combination of 14-3-3ζ and BIG1 is required for GABAAR membrane expression. Our results provide a potential promising therapeutic target for neurological disorders involving GABAergic synaptic transmission.
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Affiliation(s)
- Cuixian Li
- Experiment Teaching & Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Shen Huang
- Experiment Teaching & Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Jin Peng
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510515, China
| | - Tianguo Hong
- Experiment Teaching & Administration Center, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Chun Zhou
- Laboratory of Immunopharmacology, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China.
- SMU-KI United Medical Inflammatory Center, School of Pharmaceutical Sciences; Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, 510515, China.
| | - Jie Tang
- Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, 510515, China.
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.
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8
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Mabuchi Y, Cui X, Xie L, Kim H, Jiang T, Yapici N. GABA-mediated inhibition in visual feedback neurons fine-tunes Drosophila male courtship. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.25.525544. [PMID: 36747836 PMCID: PMC9900824 DOI: 10.1101/2023.01.25.525544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Vision is critical for the regulation of mating behaviors in many species. Here, we discovered that the Drosophila ortholog of human GABA A -receptor-associated protein (GABARAP) is required to fine-tune male courtship by modulating the activity of visual feedback neurons, lamina tangential cells (Lat). GABARAP is a ubiquitin-like protein that regulates cell-surface levels of GABA A receptors. Knocking down GABARAP or GABA A receptors in Lat neurons or hyperactivating them induces male courtship toward other males. Inhibiting Lat neurons, on the other hand, delays copulation by impairing the ability of males to follow females. Remarkably, the human ortholog of Drosophila GABARAP restores function in Lat neurons. Using in vivo two-photon imaging and optogenetics, we show that Lat neurons are functionally connected to neural circuits that mediate visually-guided courtship pursuits in males. Our work reveals a novel physiological role for GABARAP in fine-tuning the activity of a visual circuit that tracks a mating partner during courtship.
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Affiliation(s)
- Yuta Mabuchi
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
| | - Xinyue Cui
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
| | - Lily Xie
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
| | - Haein Kim
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
| | - Tianxing Jiang
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
| | - Nilay Yapici
- Department of Neurobiology and Behavior, Cornell University, 14853, Ithaca, NY, USA
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Varga VB, Keresztes F, Sigmond T, Vellai T, Kovács T. The evolutionary and functional divergence of the Atg8 autophagy protein superfamily. Biol Futur 2022; 73:375-384. [PMID: 35731422 DOI: 10.1007/s42977-022-00123-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/28/2022] [Indexed: 01/27/2023]
Abstract
Autophagy is a highly conserved self-degradation process of eukaryotic cells which is required for the effective elimination of damaged and unnecessary cytosolic constituents. Defects in the process can cause the intracellular accumulation of such damages, thereby leading to the senescence and subsequent loss of the affected cell. Defective autophagy hence is implicated in the development of various degenerative processes, including cancer, neurodegenerative diseases, diabetes, tissue atrophy and fibrosis, and immune deficiency, as well as in accelerated aging. The autophagic process is mediated by numerous autophagy-related (ATG) proteins, among which the ATG8/LC3/GABARAP (Microtubule-associated protein 1A/1B-light chain 3/Gammaaminobutyric acid receptor-associated protein) superfamily has a pivotal role in the formation and maturation of autophagosome, a key (macro) autophagic structure (the autophagosome sequesters parts of the cytoplasm which are destined for breakdown). While in the unicellular yeast there is only a single ATG8 protein, metazoan systems usually contain more ATG8 paralogs. ATG8 paralogs generally display tissue-specific expression patterns and their functions are not strictly restricted to autophagy. For example, GABARAP proteins also play a role in intracellular vesicle transport, and, in addition to autophagosome formation, ATG8 also functions in selective autophagy. In this review, we summarize the functional diversity of ATG8/LC3/GABARAP proteins, using tractable genetic models applied in autophagy research.
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Affiliation(s)
- Virginia B Varga
- Department of Genetics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary
| | - Fanni Keresztes
- Department of Genetics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary
| | - Tímea Sigmond
- Department of Genetics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary
| | - Tibor Vellai
- Department of Genetics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary.,ELKH-ELTE Genetics Research Group, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary
| | - Tibor Kovács
- Department of Genetics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, H-1117, Hungary.
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10
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Sawaged S, Mota T, Piplani H, Thakur R, Lall D, McCabe E, Seo S, Sutterwala FS, Feuer R, Gottlieb RA, Sin J. TBK1 and GABARAP family members suppress Coxsackievirus B infection by limiting viral production and promoting autophagic degradation of viral extracellular vesicles. PLoS Pathog 2022; 18:e1010350. [PMID: 36044516 PMCID: PMC9469980 DOI: 10.1371/journal.ppat.1010350] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 09/13/2022] [Accepted: 08/18/2022] [Indexed: 11/23/2022] Open
Abstract
Host-pathogen dynamics are constantly at play during enteroviral infection. Coxsackievirus B (CVB) is a common juvenile enterovirus that infects multiple organs and drives inflammatory diseases including acute pancreatitis and myocarditis. Much like other enteroviruses, CVB is capable of manipulating host machinery to hijack and subvert autophagy for its benefit. We have previously reported that CVB triggers the release of infectious extracellular vesicles (EVs) which originate from autophagosomes. These EVs facilitate efficient dissemination of infectious virus. Here, we report that TBK1 (Tank-binding kinase 1) suppresses release of CVB-induced EVs. TBK1 is a multimeric kinase that directly activates autophagy adaptors for efficient cargo recruitment and induces type-1 interferons during viral-mediated STING recruitment. Positioning itself at the nexus of pathogen elimination, we hypothesized that loss of TBK1 could exacerbate CVB infection due to its specific role in autophagosome trafficking. Here we report that infection with CVB during genetic TBK1 knockdown significantly increases viral load and potentiates the bulk release of viral EVs. Similarly, suppressing TBK1 with small interfering RNA (siRNA) caused a marked increase in intracellular virus and EV release, while treatment in vivo with the TBK1-inhibitor Amlexanox exacerbated viral pancreatitis and EV spread. We further demonstrated that viral EV release is mediated by the autophagy modifier proteins GABARAPL1 and GABARAPL2 which facilitate autophagic flux. We observe that CVB infection stimulates autophagy and increases the release of GABARAPL1/2-positive EVs. We conclude that TBK1 plays additional antiviral roles by inducing autophagic flux during CVB infection independent of interferon signaling, and the loss of TBK1 better allows CVB-laden autophagosomes to circumvent lysosomal degradation, increasing the release of virus-laden EVs. This discovery sheds new light on the mechanisms involved in viral spread and EV propagation during acute enteroviral infection and highlights novel intracellular trafficking protein targets for antiviral therapy. Coxsackievirus B (CVB) is a significant human enterovirus that can cause myocarditis, meningitis, and pancreatitis. The subversion of host immunity and mechanisms of viral dissemination are critical factors which promote pathogenesis. We had previously reported that following infection, CVB becomes engulfed by autophagosomes which evade lysosomal degradation and instead get released as infectious extracellular vesicles (EVs). In this current study, we report that in addition to its traditional role in interferon-mediated antiviral signaling, TANK-binding kinase (TBK1) is crucial in limiting viral production and EV-based viral egress through the autophagy pathway. Indeed, in the absence of TBK1, we observe (i) a disruption in autophagic flux, (ii) significant increases in intracellular viral burden and viral EV release, and (iii) elevated viral load in both in vitro and in vivo models of infection. EVs isolated from TBK1-deficient cells or mice treated with the TBK1-inhibitor Amlexanox were more infectious compared to controls. In all, the dual role TBK1 plays in suppressing viral escape in addition to mediating antiviral immunity makes it a promising therapeutic target for the treatment of CVB infection.
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Affiliation(s)
- Savannah Sawaged
- The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Thomas Mota
- The Center for Neural Science and Medicine, Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Honit Piplani
- The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Reetu Thakur
- The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Deepti Lall
- The Center for Neural Science and Medicine, Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Elizabeth McCabe
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Soojung Seo
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Fayyaz S. Sutterwala
- Department of Medicine, Women’s Guild Lung Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Ralph Feuer
- The Integrated Regenerative Research Institute at San Diego State University, San Diego, California, United States of America
| | - Roberta A. Gottlieb
- The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Jon Sin
- The Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, United States of America
- * E-mail:
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11
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Chan JCY, Gorski SM. Unlocking the gate to GABARAPL2. Biol Futur 2022; 73:157-169. [PMID: 35486231 DOI: 10.1007/s42977-022-00119-2] [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: 11/29/2021] [Accepted: 04/08/2022] [Indexed: 10/18/2022]
Abstract
GABARAPL2 was initially characterized for its involvement in protein transport and membrane fusion events, but has since gained notoriety for its role in autophagy. GABARAPL2 is frequently studied alongside its GABARAP subfamily members, GABARAP and GABARAPL1. Although functional redundancy exists among the subfamily members, a complex network of molecular interactions, physiological processes and pathologies can be primarily related to GABARAPL2. GABARAPL2 has a multifaceted role, ranging from cellular differentiation to intracellular degradation. Much of what we know about GABARAPL2 is gained through identifying its interacting partners-a list that is constantly growing. In this article, we review both the autophagy-dependent and autophagy-independent roles of GABARAPL2, and emphasize their implications for both health and disease.
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Affiliation(s)
- Jennifer C Y Chan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.,Canada's Michael Smith Genome Sciences Centre at BC Cancer, Vancouver, BC, V5Z 1L3, Canada
| | - Sharon M Gorski
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada. .,Canada's Michael Smith Genome Sciences Centre at BC Cancer, Vancouver, BC, V5Z 1L3, Canada. .,Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
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12
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Yang D, Wu X, Wang W, Zhou Y, Wang Z. Ciliary Type III Adenylyl Cyclase in the VMH Is Crucial for High-Fat Diet-Induced Obesity Mediated by Autophagy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2102568. [PMID: 34783461 PMCID: PMC8787410 DOI: 10.1002/advs.202102568] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Neuronal primary cilia are crucial for body weight maintenance. Type III adenylyl cyclase (AC3) is abundantly enriched in neuronal cilia, and mice with global AC3 ablation are obese. However, whether AC3 regulates body weight through its ciliary expression and the mechanism underlying this potential regulation are not clear. In this study, humanized AC3 knock-in mice that are resistant to high-fat diet (HFD)-induced obesity are generated, and increases in the number and length of cilia in the ventromedial hypothalamus (VMH) are shown. It is demonstrated that mice with specifically knocked down ciliary AC3 expression in the VMH show pronounced HFD-induced obesity. In addition, in vitro and in vivo analyses of the VMH show that ciliary AC3 regulates autophagy by binding an autophagy-related gene, gamma-aminobutyric acid A receptor-associated protein (GABARAP). Mice with GABARAP knockdown in the VMH exhibit exacerbated HFD-induced obesity. Overall, the findings may reveal a potential mechanism by which ciliary AC3 expression regulates body weight in the mouse VMH.
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Affiliation(s)
- Dong Yang
- College of Life ScienceInstitute of Life Science and Green DevelopmentHebei UniversityBaodingHebei071002China
| | - Xiangbo Wu
- College of Life ScienceInstitute of Life Science and Green DevelopmentHebei UniversityBaodingHebei071002China
| | - Weina Wang
- College of Life ScienceInstitute of Life Science and Green DevelopmentHebei UniversityBaodingHebei071002China
| | - Yanfen Zhou
- College of Life ScienceInstitute of Life Science and Green DevelopmentHebei UniversityBaodingHebei071002China
| | - Zhenshan Wang
- College of Life ScienceInstitute of Life Science and Green DevelopmentHebei UniversityBaodingHebei071002China
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13
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Does GEC1 Enhance Expression and Forward Trafficking of the Kappa Opioid Receptor (KOR) via Its Ability to Interact with NSF Directly? Handb Exp Pharmacol 2022; 271:83-96. [PMID: 33404775 PMCID: PMC9126001 DOI: 10.1007/164_2020_398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We reported previously that GEC1 (glandular epithelial cell 1), a member of microtubule-associated proteins (MAPs), interacted directly with the C-tail of KOR (KCT) and tubulin and enhanced cell surface expression of KOR in CHO cells by facilitating its trafficking along the export pathway. Two GEC1 analogs (GABARAP and GATE16) were also shown to increase KOR expression. In addition, to understand the underlying mechanism, we demonstrated that N-ethylmaleimide-sensitive factor (NSF), an essential component for membrane fusion, co-immunoprecipitated with GEC1 from brain extracts. In this study, using pull-down techniques, we have found that (1) GEC1 interacts with NSF directly and prefers the ADP-bound NSF to the ATP-bound NSF; (2) D1 and/or D2 domain(s) of NSF interact with GEC1, but the N domain of NSF does not; (3) NSF does not interact with KCT directly, but forms a protein complex with KCT via GEC1; (4) NSF and/or α-SNAP do not affect KCT-GEC1 interaction. Thus, GEC1 (vs the α-SNAP/SNAREs complex) binds to NSF in distinctive ways in terms of the ADP- or ATP-bound form and domains of NSF involved. In conclusion, GEC1 may, via its direct interactions with KOR, NSF, and tubulin, enhance trafficking and fusion of KOR-containing vesicles selectively along the export pathway, which leads to increase in surface expression of KOR. GABARAP and GATE16 may enhance KOR expression in a similar way.
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14
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Xie MJ, Iwata K, Ishikawa Y, Nomura Y, Tani T, Murata K, Fukazawa Y, Matsuzaki H. Autistic-Like Behavior and Impairment of Serotonin Transporter and AMPA Receptor Trafficking in N-Ethylmaleimide Sensitive Factor Gene-Deficient Mice. Front Genet 2021; 12:748627. [PMID: 34745222 PMCID: PMC8563833 DOI: 10.3389/fgene.2021.748627] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/04/2021] [Indexed: 01/22/2023] Open
Abstract
Autism spectrum disorder (ASD), characterized by profound impairment in social interactions and communication skills, is the most common neurodevelopmental disorder. Many studies on the mechanisms underlying the development of ASD have focused on the serotonergic system; however, these studies have failed to completely elucidate the mechanisms. We previously identified N-ethylmaleimide-sensitive factor (NSF) as a new serotonin transporter (SERT)-binding protein and described its importance in SERT membrane trafficking and uptake in vitro. In the present study, we generated Nsf +/- mice and investigated their behavioral, neurotransmitter, and neurophysiological phenotypes in vivo. Nsf +/- mice exhibited abnormalities in sociability, communication, repetitiveness, and anxiety. Additionally, Nsf loss led to a decrease in membrane SERT expression in the raphe and accumulation of glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors at the synaptic membrane surface in the hippocampal CA1 region. We found that postsynaptic density and long-term depression were impaired in the hippocampal CA1 region of Nsf +/- mice. Taken together, these findings demonstrate that NSF plays a role in synaptic plasticity and glutamatergic and serotonergic systems, suggesting a possible mechanism by which the gene is linked to the pathophysiology of autistic behaviors.
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Affiliation(s)
- Min-Jue Xie
- Division of Development of Mental Functions, Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan.,United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka University, Osaka, Japan
| | - Keiko Iwata
- Division of Development of Mental Functions, Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan.,United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka University, Osaka, Japan
| | - Yasuyuki Ishikawa
- Department of Systems Life Engineering, Maebashi Institute of Technology, Maebashi, Japan
| | - Yuki Nomura
- School of Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Tomomi Tani
- School of Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Koshi Murata
- Division of Brain Structures and Function, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Yugo Fukazawa
- Division of Development of Mental Functions, Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan.,Division of Brain Structures and Function, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Hideo Matsuzaki
- Division of Development of Mental Functions, Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,Life Science Innovation Center, University of Fukui, Fukui, Japan.,United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka University, Osaka, Japan
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15
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ATG4D is the main ATG8 delipidating enzyme in mammalian cells and protects against cerebellar neurodegeneration. Cell Death Differ 2021; 28:2651-2672. [PMID: 33795848 PMCID: PMC8408152 DOI: 10.1038/s41418-021-00776-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 02/01/2023] Open
Abstract
Despite the great advances in autophagy research in the last years, the specific functions of the four mammalian Atg4 proteases (ATG4A-D) remain unclear. In yeast, Atg4 mediates both Atg8 proteolytic activation, and its delipidation. However, it is not clear how these two roles are distributed along the members of the ATG4 family of proteases. We show that these two functions are preferentially carried out by distinct ATG4 proteases, being ATG4D the main delipidating enzyme. In mammalian cells, ATG4D loss results in accumulation of membrane-bound forms of mATG8s, increased cellular autophagosome number and reduced autophagosome average size. In mice, ATG4D loss leads to cerebellar neurodegeneration and impaired motor coordination caused by alterations in trafficking/clustering of GABAA receptors. We also show that human gene variants of ATG4D associated with neurodegeneration are not able to fully restore ATG4D deficiency, highlighting the neuroprotective role of ATG4D in mammals.
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16
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Ye J, Zou G, Zhu R, Kong C, Miao C, Zhang M, Li J, Xiong W, Wang C. Structural basis of GABARAP-mediated GABA A receptor trafficking and functions on GABAergic synaptic transmission. Nat Commun 2021; 12:297. [PMID: 33436612 PMCID: PMC7803741 DOI: 10.1038/s41467-020-20624-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 12/04/2020] [Indexed: 01/07/2023] Open
Abstract
GABAA receptors (GABAARs) are the primary fast inhibitory ion channels in the central nervous system. Dysfunction of trafficking and localization of GABAARs to cell membranes is clinically associated with severe psychiatric disorders in humans. The GABARAP protein is known to support the stability of GABAARs in synapses, but the underlying molecular mechanisms remain to be elucidated. Here, we show that GABARAP/GABARAPL1 directly binds to a previously unappreciated region in the γ2 subunit of GABAAR. We demonstrate that GABARAP functions to stabilize GABAARs via promoting its trafficking pathway instead of blocking receptor endocytosis. The GABARAPL1-γ2-GABAAR crystal structure reveals the mechanisms underlying the complex formation. We provide evidence showing that phosphorylation of γ2-GABAAR differentially modulate the receptor's binding to GABARAP and the clathrin adaptor protein AP2. Finally, we demonstrate that GABAergic synaptic currents are reduced upon specific blockage of the GABARAP-GABAAR complex formation. Collectively, our results reveal that GABARAP/GABARAPL1, but not other members of the Atg8 family proteins, specifically regulates synaptic localization of GABAARs via modulating the trafficking of the receptor.
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Affiliation(s)
- Jin Ye
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China
| | - Guichang Zou
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China
| | - Ruichi Zhu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
- Center of Systems Biology and Human Health, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
| | - Chao Kong
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China
| | - Chenjian Miao
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
- Center of Systems Biology and Human Health, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
| | - Jianchao Li
- Division of Cell, Developmental and Integrative Biology, School of Medicine, South China University of Technology, 510006, Guangzhou, P.R. China.
| | - Wei Xiong
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China.
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, 200031, Shanghai, P.R. China.
| | - Chao Wang
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027, Hefei, P.R. China.
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17
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McMillan P, Wheeler J, Gatlin RE, Taylor L, Strovas T, Baum M, Bird TD, Latimer C, Keene CD, Kraemer BC, Liachko NF. Adult onset pan-neuronal human tau tubulin kinase 1 expression causes severe cerebellar neurodegeneration in mice. Acta Neuropathol Commun 2020; 8:200. [PMID: 33228809 PMCID: PMC7684928 DOI: 10.1186/s40478-020-01073-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/07/2020] [Indexed: 12/18/2022] Open
Abstract
The kinase TTBK1 is predominantly expressed in the central nervous system and has been implicated in neurodegenerative diseases including Alzheimer’s disease, frontotemporal lobar degeneration, and amyotrophic lateral sclerosis through its ability to phosphorylate the proteins tau and TDP-43. Mutations in the closely related gene TTBK2 cause spinocerebellar ataxia, type 11. However, it remains unknown whether altered TTBK1 activity alone can drive neurodegeneration. In order to characterize the consequences of neuronal TTBK1 upregulation in adult brains, we have generated a transgenic mouse model with inducible pan-neuronal expression of human TTBK1. We find that these inducible TTBK1 transgenic mice (iTTBK1 Tg) exhibit motor and cognitive phenotypes, including decreased grip strength, hyperactivity, limb-clasping, and spatial memory impairment. These behavioral phenotypes occur in conjunction with progressive weight loss, neuroinflammation, and severe cerebellar degeneration with Purkinje neuron loss. Phenotype onset begins weeks after TTBK1 induction, culminating in average mortality around 7 weeks post induction. The iTTBK1 Tg animals lack any obvious accumulation of pathological tau or TDP-43, indicating that TTBK1 expression drives neurodegeneration in the absence of detectable pathological protein deposition. In exploring TTBK1 functions, we identified the autophagy related protein GABARAP to be a novel interacting partner of TTBK1 and show that GABARAP protein levels increase in the brain following induction of TTBK1. These iTTBK1 Tg mice exhibit phenotypes reminiscent of spinocerebellar ataxia, and represent a new model of cerebellar neurodegeneration.
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18
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Eck F, Phuyal S, Smith MD, Kaulich M, Wilkinson S, Farhan H, Behrends C. ACSL3 is a novel GABARAPL2 interactor that links ufmylation and lipid droplet biogenesis. J Cell Sci 2020; 133:jcs243477. [PMID: 32843575 DOI: 10.1242/jcs.243477] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 08/10/2020] [Indexed: 12/12/2022] Open
Abstract
While studies of the autophagy-related (ATG) genes in knockout models have led to an explosion of knowledge about the functions of autophagy components, the exact roles of LC3 and GABARAP family proteins (human ATG8 equivalents) are still poorly understood. A major drawback in understanding their roles is that the available interactome data has largely been acquired using overexpression systems. To overcome these limitations, we employed CRISPR/Cas9-based genome-editing to generate a panel of cells in which human ATG8 genes were tagged at their natural chromosomal locations with an N-terminal affinity epitope. This cellular resource was employed to map endogenous GABARAPL2 protein complexes using interaction proteomics. This approach identified the ER-associated protein and lipid droplet (LD) biogenesis factor ACSL3 as a stabilizing GABARAPL2-binding partner. GABARAPL2 bound ACSL3 in a manner dependent on its LC3-interacting regions, whose binding site in GABARAPL2 was required to recruit the latter to the ER. Through this interaction, the UFM1-activating enzyme UBA5 became anchored at the ER. Furthermore, ACSL3 depletion and LD induction affected the abundance of several ufmylation components and ER-phagy. Together these data allow us to define ACSL3 as a novel regulator of the enigmatic UFM1 conjugation pathway.
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Affiliation(s)
- Franziska Eck
- Munich Cluster for Systems Neurology (SyNergy), Medical Faculty, Ludwig-Maximilians-University München, Feodor-Lynen Strasse 17, 81377 Munich, Germany
| | - Santosh Phuyal
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, 0372 Oslo, Norway
| | - Matthew D Smith
- Cancer Research UK Edinburgh Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Manuel Kaulich
- Institute of Biochemistry II, Goethe University School of Medicine, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Simon Wilkinson
- Cancer Research UK Edinburgh Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK
| | - Hesso Farhan
- Institute of Basic Medical Sciences, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, 0372 Oslo, Norway
| | - Christian Behrends
- Munich Cluster for Systems Neurology (SyNergy), Medical Faculty, Ludwig-Maximilians-University München, Feodor-Lynen Strasse 17, 81377 Munich, Germany
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19
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Bu F, Yang M, Guo X, Huang W, Chen L. Multiple Functions of ATG8 Family Proteins in Plant Autophagy. Front Cell Dev Biol 2020; 8:466. [PMID: 32596242 PMCID: PMC7301642 DOI: 10.3389/fcell.2020.00466] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/19/2020] [Indexed: 11/13/2022] Open
Abstract
Autophagy is a major degradation process of cytoplasmic components in eukaryotes, and executes both bulk and selective degradation of targeted cargos. A set of autophagy-related (ATG) proteins participate in various stages of the autophagic process. Among ATGs, ubiquitin-like protein ATG8 plays a central role in autophagy. The ATG8 protein is conjugated to the membrane lipid phosphatidylethanolamine in a ubiquitin-like conjugation reaction that is essential for autophagosome formation. In addition, ATG8 interacts with various adaptor/receptor proteins to recruit specific cargos for degradation by selective autophagy. The ATG8-interacting proteins usually contain the ATG8-interacting motif (AIM) or the ubiquitin-interacting motif (UIM) for ATG8 binding. Unlike a single ATG8 gene in yeast, multiple ATG8 orthologs have been identified in the plant kingdom. The large diversity within the ATG8 family may explain the various functions of selective autophagy in plants. Here, we discuss and summarize the current view of the structure and function of ATG8 proteins in plants.
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Affiliation(s)
- Fan Bu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Mingkang Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Xu Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Wei Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Liang Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
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20
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mTOR-Related Cell-Clearing Systems in Epileptic Seizures, an Update. Int J Mol Sci 2020; 21:ijms21051642. [PMID: 32121250 PMCID: PMC7084443 DOI: 10.3390/ijms21051642] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
Recent evidence suggests that autophagy impairment is implicated in the epileptogenic mechanisms downstream of mTOR hyperactivation. This holds true for a variety of genetic and acquired epileptic syndromes besides malformations of cortical development which are classically known as mTORopathies. Autophagy suppression is sufficient to induce epilepsy in experimental models, while rescuing autophagy prevents epileptogenesis, improves behavioral alterations, and provides neuroprotection in seizure-induced neuronal damage. The implication of autophagy in epileptogenesis and maturation phenomena related to seizure activity is supported by evidence indicating that autophagy is involved in the molecular mechanisms which are implicated in epilepsy. In general, mTOR-dependent autophagy regulates the proliferation and migration of inter-/neuronal cortical progenitors, synapse development, vesicular release, synaptic plasticity, and importantly, synaptic clustering of GABAA receptors and subsequent excitatory/inhibitory balance in the brain. Similar to autophagy, the ubiquitin–proteasome system is regulated downstream of mTOR, and it is implicated in epileptogenesis. Thus, mTOR-dependent cell-clearing systems are now taking center stage in the field of epilepsy. In the present review, we discuss such evidence in a variety of seizure-related disorders and models. This is expected to provide a deeper insight into the molecular mechanisms underlying seizure activity.
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21
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Huber J, Obata M, Gruber J, Akutsu M, Löhr F, Rogova N, Güntert P, Dikic I, Kirkin V, Komatsu M, Dötsch V, Rogov VV. An atypical LIR motif within UBA5 (ubiquitin like modifier activating enzyme 5) interacts with GABARAP proteins and mediates membrane localization of UBA5. Autophagy 2020; 16:256-270. [PMID: 30990354 PMCID: PMC6984602 DOI: 10.1080/15548627.2019.1606637] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 03/15/2019] [Accepted: 03/27/2019] [Indexed: 12/15/2022] Open
Abstract
Short linear motifs, known as LC3-interacting regions (LIRs), interact with mactoautophagy/autophagy modifiers (Atg8/LC3/GABARAP proteins) via a conserved universal mechanism. Typically, this includes the occupancy of 2 hydrophobic pockets on the surface of Atg8-family proteins by 2 specific aromatic and hydrophobic residues within the LIR motifs. Here, we describe an alternative mechanism of Atg8-family protein interaction with the non-canonical UBA5 LIR, an E1-like enzyme of the ufmylation pathway that preferentially interacts with GABARAP but not LC3 proteins. By solving the structures of both GABARAP and GABARAPL2 in complex with the UBA5 LIR, we show that in addition to the binding to the 2 canonical hydrophobic pockets (HP1 and HP2), a conserved tryptophan residue N-terminal of the LIR core sequence binds into a novel hydrophobic pocket on the surface of GABARAP proteins, which we term HP0. This mode of action is unique for UBA5 and accompanied by large rearrangements of key residues including the side chains of the gate-keeping K46 and the adjacent K/R47 in GABARAP proteins. Swapping mutations in LC3B and GABARAPL2 revealed that K/R47 is the key residue in the specific binding of GABARAP proteins to UBA5, with synergetic contributions of the composition and dynamics of the loop L3. Finally, we elucidate the physiological relevance of the interaction and show that GABARAP proteins regulate the localization and function of UBA5 on the endoplasmic reticulum membrane in a lipidation-independent manner.Abbreviations: ATG: AuTophaGy-related; EGFP: enhanced green fluorescent protein; GABARAP: GABA-type A receptor-associated protein; ITC: isothermal titration calorimetry; KO: knockout; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NMR: nuclear magnetic resonance; RMSD: root-mean-square deviation of atomic positions; TKO: triple knockout; UBA5: ubiquitin like modifier activating enzyme 5.
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Affiliation(s)
- Jessica Huber
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - Miki Obata
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Jens Gruber
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - Masato Akutsu
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt am Main, Germany
| | - Frank Löhr
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - Natalia Rogova
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - Peter Güntert
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
- Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Ivan Dikic
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt am Main, Germany
- Institute of Biochemistry II, School of Medicine, Frankfurt am Main, Germany
| | - Vladimir Kirkin
- Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, UK
| | - Masaaki Komatsu
- Department of Biochemistry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
- Department of Physiology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Volker Dötsch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
| | - Vladimir V. Rogov
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, Germany
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22
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Abstract
Autophagy is the major cellular pathway to degrade dysfunctional organelles and protein aggregates. Autophagy is particularly important in neurons, which are terminally differentiated cells that must last the lifetime of the organism. There are both constitutive and stress-induced pathways for autophagy in neurons, which catalyze the turnover of aged or damaged mitochondria, endoplasmic reticulum, other cellular organelles, and aggregated proteins. These pathways are required in neurodevelopment as well as in the maintenance of neuronal homeostasis. Here we review the core components of the pathway for autophagosome biogenesis, as well as the cell biology of bulk and selective autophagy in neurons. Finally, we discuss the role of autophagy in neuronal development, homeostasis, and aging and the links between deficits in autophagy and neurodegeneration.
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Affiliation(s)
- Andrea K H Stavoe
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA;
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA;
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23
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Hui KK, Takashima N, Watanabe A, Chater TE, Matsukawa H, Nekooki-Machida Y, Nilsson P, Endo R, Goda Y, Saido TC, Yoshikawa T, Tanaka M. GABARAPs dysfunction by autophagy deficiency in adolescent brain impairs GABA A receptor trafficking and social behavior. SCIENCE ADVANCES 2019; 5:eaau8237. [PMID: 30989111 PMCID: PMC6457945 DOI: 10.1126/sciadv.aau8237] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/20/2019] [Indexed: 05/02/2023]
Abstract
Dysfunctional mTOR signaling is associated with the pathogenesis of neurodevelopmental and neuropsychiatric disorders. However, it is unclear what molecular mechanisms and pathogenic mediators are involved and whether mTOR-regulated autophagy continues to be crucial beyond neurodevelopment. Here, we selectively deleted Atg7 in forebrain GABAergic interneurons in adolescent mice and unexpectedly found that these mice showed a set of behavioral deficits similar to Atg7 deletion in forebrain excitatory neurons. By unbiased quantitative proteomic analysis, we identified γ-aminobutyric acid receptor-associated protein-like 2 (GABARAPL2) to differentially form high-molecular weight species in autophagy-deficient brains. Further functional analyses revealed a novel pathogenic mechanism involving the p62-dependent sequestration of GABARAP family proteins, leading to the reduction of surface GABAA receptor levels. Our work demonstrates a novel physiological role for autophagy in regulating GABA signaling beyond postnatal neurodevelopment, providing a potential mechanism for the reduced inhibitory inputs observed in neurodevelopmental and neuropsychiatric disorders with mTOR hyperactivation.
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Affiliation(s)
- Kelvin K. Hui
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Noriko Takashima
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Akiko Watanabe
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Thomas E. Chater
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Hiroshi Matsukawa
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Laboratory for Behavioral Genetics, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Yoko Nekooki-Machida
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Per Nilsson
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge 141 57, Sweden
| | - Ryo Endo
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Yukiko Goda
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Takaomi C. Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Motomasa Tanaka
- Laboratory for Protein Conformation Diseases, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
- Corresponding author.
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24
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Modulation of inhibitory plasticity in basal ganglia output nuclei of patients with Parkinson's disease. Neurobiol Dis 2019; 124:46-56. [DOI: 10.1016/j.nbd.2018.10.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/17/2018] [Accepted: 10/31/2018] [Indexed: 01/07/2023] Open
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25
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Mele M, Costa RO, Duarte CB. Alterations in GABA A-Receptor Trafficking and Synaptic Dysfunction in Brain Disorders. Front Cell Neurosci 2019; 13:77. [PMID: 30899215 PMCID: PMC6416223 DOI: 10.3389/fncel.2019.00077] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/15/2019] [Indexed: 12/12/2022] Open
Abstract
GABAA receptors (GABAAR) are the major players in fast inhibitory neurotransmission in the central nervous system (CNS). Regulation of GABAAR trafficking and the control of their surface expression play important roles in the modulation of the strength of synaptic inhibition. Different pieces of evidence show that alterations in the surface distribution of GABAAR and dysregulation of their turnover impair the activity of inhibitory synapses. A diminished efficacy of inhibitory neurotransmission affects the excitatory/inhibitory balance and is a common feature of various disorders of the CNS characterized by an increased excitability of neuronal networks. The synaptic pool of GABAAR is mainly controlled through regulation of internalization, recycling and lateral diffusion of the receptors. Under physiological condition these mechanisms are finely coordinated to define the strength of GABAergic synapses. In this review article, we focus on the alteration in GABAAR trafficking with an impact on the function of inhibitory synapses in various disorders of the CNS. In particular we discuss how similar molecular mechanisms affecting the synaptic distribution of GABAAR and consequently the excitatory/inhibitory balance may be associated with a wide diversity of pathologies of the CNS, from psychiatric disorders to acute alterations leading to neuronal death. A better understanding of the cellular and molecular mechanisms that contribute to the impairment of GABAergic neurotransmission in these disorders, in particular the alterations in GABAAR trafficking and surface distribution, may lead to the identification of new pharmacological targets and to the development of novel therapeutic strategies.
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Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Rui O Costa
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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26
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Li K, Chen HS, Li D, Li HH, Wang J, Jia L, Wu PF, Long LH, Hu ZL, Chen JG, Wang F. SAR405, a Highly Specific VPS34 Inhibitor, Disrupts Auditory Fear Memory Consolidation of Mice via Facilitation of Inhibitory Neurotransmission in Basolateral Amygdala. Biol Psychiatry 2019; 85:214-225. [PMID: 30253884 DOI: 10.1016/j.biopsych.2018.07.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/18/2018] [Accepted: 07/29/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Autophagy has been demonstrated to play an important role in memory deficits as well as the degradation of neurotransmitter receptors. SAR405 is a newly discovered inhibitor that can specifically inhibit vacuolar sorting protein 34 and prevent autophagosome biogenesis. However, the effects of SAR405 on memory processes remain largely unknown. METHODS Western blotting, immunofluorescence, and transmission electron microscopy were used to assess the level of autophagy after fear conditioning and SAR405 treatment. Behavioral tests, biotinylation assay, electrophysiology, and co-immunoprecipitation were used to unravel the mechanisms of SAR405 in memory consolidation. RESULTS SAR405 infusion into the basolateral amygdala impaired long-term memory through autophagy inhibition. Furthermore, the trafficking of gamma-aminobutyric acid type A receptors (GABAARs) following fear conditioning was disrupted by SAR405, and the decreased frequency and amplitude of miniature inhibitory postsynaptic currents induced by fear conditioning were also reversed by SAR405, suggesting that SAR405 disrupted memory consolidation through blockade of the downregulated inhibitory neurotransmission in basolateral amygdala. GABAAR-associated protein (GABARAP) and its interaction with GABAAR γ2 subunit were found to be upregulated after fear conditioning, and SAR405 could suppress this increased interaction. Moreover, disruption of the GABARAP-GABAAR binding by a trans-activating transcriptional activator-GABARAP inhibitory peptide blocked the decrease in surface expression of GABAARs and attenuated long-term memory. CONCLUSIONS The present study suggests that SAR405 can prevent the memory consolidation via intervening autophagy and GABAAR trafficking and has a potential therapeutic value for disorders characterized by exaggerated fear memories, such as posttraumatic stress disorder.
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Affiliation(s)
- Kuan Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Sheng Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Di Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hou-Hong Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lei Jia
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Peng-Fei Wu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, the Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China
| | - Li-Hong Long
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, the Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory of Neurological Diseases, Ministry of Education of China, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China
| | - Zhuang-Li Hu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, the Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China
| | - Jian-Guo Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, the Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory of Neurological Diseases, Ministry of Education of China, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China; Collaborative Innovation Center for Brain Science, Wuhan, China.
| | - Fang Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, the Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory of Neurological Diseases, Ministry of Education of China, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China; Collaborative Innovation Center for Brain Science, Wuhan, China.
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27
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Li W, Zhang L. Regulation of ATG and Autophagy Initiation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1206:41-65. [PMID: 31776979 DOI: 10.1007/978-981-15-0602-4_2] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
ATG is involved in multiple processes of autophagosome formation, including the initial phase of autophagy. The mammalian autophagy complex-ULK1 complex is composed of ULK1, FIP200, ATG13 and ATG101, and the yeast autophagy initiation complex-ATG1 complex is composed of ATG1, ATG13, ATG17, ATG29 and ATG31. After this complex is activated, it binds and phosphorylates ATG9 on the vesicles. Then PI3KC3-C1 (yeast: ATG34: ATG15: ATG6: ATG14 or mammal animal: ATG34: ATG15: BECN1: ATG14L) is recruited to the PAS. Further, ATG12-ATG5-ATG16 complex is localized on PAS (Yeast) or localized on the outer surface of the membrane (mammal) and makes binding of ATG8 (LC3) with PE to form ATG8-PE complex, promoting autophagic membrane elongation, closure and formation autophagosome and autophagosome lysosome.
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Affiliation(s)
- Wen Li
- Department of Immunology, School of Basic Medical Science, Shandong University, 44# Wenhua Xi Road, Jinan, 250012, China
| | - Lining Zhang
- Department of Immunology, School of Basic Medical Science, Shandong University, 44# Wenhua Xi Road, Jinan, 250012, China.
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28
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Möckel C, Kubiak J, Schillinger O, Kühnemuth R, Della Corte D, Schröder GF, Willbold D, Strodel B, Seidel CAM, Neudecker P. Integrated NMR, Fluorescence, and Molecular Dynamics Benchmark Study of Protein Mechanics and Hydrodynamics. J Phys Chem B 2018; 123:1453-1480. [DOI: 10.1021/acs.jpcb.8b08903] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Christina Möckel
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Jakub Kubiak
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Oliver Schillinger
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Ralf Kühnemuth
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Dennis Della Corte
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Gunnar F. Schröder
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
- Physics Department, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Dieter Willbold
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Birgit Strodel
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Claus A. M. Seidel
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
| | - Philipp Neudecker
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
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29
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Fan J, Li D, Chen HS, Huang JG, Xu JF, Zhu WW, Chen JG, Wang F. Metformin produces anxiolytic-like effects in rats by facilitating GABA A receptor trafficking to membrane. Br J Pharmacol 2018; 176:297-316. [PMID: 30318707 DOI: 10.1111/bph.14519] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 09/15/2018] [Accepted: 09/19/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Altered function or expression of GABAA receptors contributes to anxiety disorders. Benzodiazepines are widely prescribed for the treatment of anxiety. However, the long-term use of benzodiazepines increases the risk of developing drug dependence and tolerance. Thus, it is urgent to explore new therapeutic approaches. Metformin is widely used to treat Type 2 diabetes and other metabolic syndromes. However, the role of metformin in psychiatric disorders, especially anxiety, remains largely unknown. EXPERIMENTAL APPROACH We examined the effects of metformin on anxiety-like behaviour of rats in open field test and elevated plus maze test. We also observed the effect of metformin (10 μM, in vitro; 100 mg·kg-1 , in vivo) on the trafficking of GABAA receptors, as mechanisms underlying the anxiolytic effects of metformin. KEY RESULTS Metformin (100 mg·kg-1 , i.p. 30 min) displayed a robust and rapid anxiolytic effect, without tolerance. Metformin up-regulated the surface expression of GABAA receptors and increased miniature inhibitory postsynaptic currents (mIPSCs). AMP-activated protein kinase (AMPK) activated by metformin-induced stimulation of forkhead box O3a (FoxO3a) transcriptional activity, followed by increased expression of GABAA receptor-associated protein (GABARAP) and its binding to GABAA receptors finally resulted in the membrane insertion of GABAA receptors. CONCLUSIONS AND IMPLICATIONS Metformin increased mIPSCs by up-regulating the membrane insertion of GABAA receptors, via a pathway involving AMPK, FoxO3a, and the GABAA receptor-associated protein. Thus metformin has a potential new use in the treatment of anxiety disorders.
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Affiliation(s)
- Jun Fan
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Di Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Sheng Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian-Geng Huang
- Department of Pharmaceutics, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jun-Feng Xu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wen-Wen Zhu
- Department of Pharmaceutics, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian-Guo Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,The Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Wuhan, China.,Hubei Key Laboratory of Drug Target Research and Pharmacodynamic Evaluation (HUST), Wuhan, China.,Laboratory of Neuropsychiatric Diseases, The Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China.,The Collaborative-Innovation Center for Brain Science, Wuhan, China
| | - Fang Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,The Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Wuhan, China.,Hubei Key Laboratory of Drug Target Research and Pharmacodynamic Evaluation (HUST), Wuhan, China.,Laboratory of Neuropsychiatric Diseases, The Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China.,The Collaborative-Innovation Center for Brain Science, Wuhan, China
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30
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Groeneweg FL, Trattnig C, Kuhse J, Nawrotzki RA, Kirsch J. Gephyrin: a key regulatory protein of inhibitory synapses and beyond. Histochem Cell Biol 2018; 150:489-508. [DOI: 10.1007/s00418-018-1725-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2018] [Indexed: 12/26/2022]
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31
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Lorenz-Guertin JM, Bambino MJ, Jacob TC. γ2 GABA AR Trafficking and the Consequences of Human Genetic Variation. Front Cell Neurosci 2018; 12:265. [PMID: 30190672 PMCID: PMC6116786 DOI: 10.3389/fncel.2018.00265] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/02/2018] [Indexed: 11/13/2022] Open
Abstract
GABA type A receptors (GABAARs) mediate the majority of fast inhibitory neurotransmission in the central nervous system (CNS). Most prevalent as heteropentamers composed of two α, two β, and a γ2 subunit, these ligand-gated ionotropic chloride channels are capable of extensive genetic diversity (α1-6, β1-3, γ1-3, δ, 𝜀, 𝜃, π, ρ1-3). Part of this selective GABAAR assembly arises from the critical role for γ2 in maintaining synaptic receptor localization and function. Accordingly, mutations in this subunit account for over half of the known epilepsy-associated genetic anomalies identified in GABAARs. Fundamental structure-function studies and cellular pathology investigations have revealed dynamic GABAAR trafficking and synaptic scaffolding as critical regulators of GABAergic inhibition. Here, we introduce in vitro and in vivo findings regarding the specific role of the γ2 subunit in receptor trafficking. We then examine γ2 subunit human genetic variation and assess disease related phenotypes and the potential role of altered GABAAR trafficking. Finally, we discuss new-age imaging techniques and their potential to provide novel insight into critical regulatory mechanisms of GABAAR function.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Matthew J Bambino
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
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32
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Birdsall V, Waites CL. Autophagy at the synapse. Neurosci Lett 2018; 697:24-28. [PMID: 29802916 DOI: 10.1016/j.neulet.2018.05.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 05/11/2018] [Accepted: 05/22/2018] [Indexed: 12/29/2022]
Abstract
As the sites of communication between neurons, synapses depend upon precisely regulated protein-protein interactions to support neurotransmitter release and reception. Moreover, neuronal synapses typically exist great distances (i.e. up to meters) away from cell bodies, which are the sources of new proteins and the major sites of protein degradation via lysosomes. Thus, synapses are uniquely sensitive to disruptions in proteostasis, and depend upon carefully orchestrated degradative mechanisms for the clearance of dysfunctional proteins. One of the primary cellular degradative pathways is macroautophagy, hereafter referred to as 'autophagy'. Although it has only recently become a focus of research in synaptic biology, emerging studies indicate that autophagy has essential functions at the synapse throughout an organism's lifetime. This review will discuss recent findings about the roles of synaptic autophagy, as well as some of the questions and issues to be considered in this field moving forward.
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Affiliation(s)
- Veronica Birdsall
- Neurobiology and Behavior Graduate Program, Columbia University, United States
| | - Clarissa L Waites
- Department of Pathology & Cell Biology, Columbia University Medical Center, United States; Department of Neuroscience, Columbia University, United States.
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33
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Zientara-Rytter K, Subramani S. AIM/LIR-based fluorescent sensors-new tools to monitor mAtg8 functions. Autophagy 2018; 14:1074-1078. [PMID: 29749795 DOI: 10.1080/15548627.2018.1454238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Abstract
Macroautophagy/autophagy, a catabolic process by which cytoplasmic materials are degraded and recycled in lysosomes/vacuoles, remains a rapidly expanding research topic with the need for constantly improved methodologies to study each step of this pathway. Recently Lee and colleagues, as well as Stolz et al., independently reported the development of new AIM/LIR-based fluorescent sensors, which mark individual endogenous mammalian Atg8-family (mAtg8) proteins without affecting the autophagic flux. When expressed in cells, each sensor selectively recognizes individual mAtg8 isoforms and distinguishes mammalian MAP1LC3/LC3 proteins from the related GABARAPs. Such selectivity was achieved by using various LC3-interacting regions with high binding affinity to either a subgroup, or a specific, mAtg8 isoform as part of the sensor. Here we discuss the utility of these sensors in autophagy research and highlight their strengths, weaknesses and future directions.
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Affiliation(s)
- Katarzyna Zientara-Rytter
- a Section of Molecular Biology, Division of Biological Sciences , University of California San Diego , La Jolla , CA , USA
| | - Suresh Subramani
- a Section of Molecular Biology, Division of Biological Sciences , University of California San Diego , La Jolla , CA , USA
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34
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Ogawa M, Nagai T, Saito Y, Miyaguchi H, Kumakura K, Abe K, Asakura T. Short-term mastication after weaning upregulates GABAergic signalling and reduces dendritic spine in thalamus. Biochem Biophys Res Commun 2018. [DOI: 10.1016/j.bbrc.2018.03.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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35
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Lorenz-Guertin JM, Jacob TC. GABA type a receptor trafficking and the architecture of synaptic inhibition. Dev Neurobiol 2018; 78:238-270. [PMID: 28901728 PMCID: PMC6589839 DOI: 10.1002/dneu.22536] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/21/2022]
Abstract
Ubiquitous expression of GABA type A receptors (GABAA R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABAA Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABAA R function. Here we review the current understanding of how GABAA Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABAA R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABAA R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
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36
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Ge Y, Kang Y, Cassidy RM, Moon KM, Lewis R, Wong ROL, Foster LJ, Craig AM. Clptm1 Limits Forward Trafficking of GABA A Receptors to Scale Inhibitory Synaptic Strength. Neuron 2018; 97:596-610.e8. [PMID: 29395912 DOI: 10.1016/j.neuron.2017.12.038] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 11/17/2017] [Accepted: 12/22/2017] [Indexed: 12/11/2022]
Abstract
In contrast with numerous studies of glutamate receptor-associated proteins and their involvement in the modulation of excitatory synapses, much less is known about mechanisms controlling postsynaptic GABAA receptor (GABAAR) numbers. Using tandem affinity purification from tagged GABAAR γ2 subunit transgenic mice and proteomic analysis, we isolated several GABAAR-associated proteins, including Cleft lip and palate transmembrane protein 1 (Clptm1). Clptm1 interacted with all GABAAR subunits tested and promoted GABAAR trapping in the endoplasmic reticulum. Overexpression of Clptm1 reduced GABAAR-mediated currents in a recombinant system, in cultured hippocampal neurons, and in brain, with no effect on glycine or AMPA receptor-mediated currents. Conversely, knockdown of Clptm1 increased phasic and tonic inhibitory transmission with no effect on excitatory synaptic transmission. Furthermore, altering the expression level of Clptm1 mimicked activity-induced inhibitory synaptic scaling. Thus, in complement to other GABAAR-associated proteins that promote receptor surface expression, Clptm1 limits GABAAR forward trafficking and regulates inhibitory homeostatic plasticity.
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Affiliation(s)
- Yuan Ge
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Yunhee Kang
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Robert M Cassidy
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Kyung-Mee Moon
- Department of Biochemistry and Molecular Biology and Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Renate Lewis
- Department of Anatomy and Neurobiology, Washington University, St. Louis, MO 63110, USA
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Leonard J Foster
- Department of Biochemistry and Molecular Biology and Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Ann Marie Craig
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC V6T 2B5, Canada.
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Vien TN, Moss SJ, Davies PA. Regulating the Efficacy of Inhibition Through Trafficking of γ-Aminobutyric Acid Type A Receptors. Anesth Analg 2017; 123:1220-1227. [PMID: 27285004 DOI: 10.1213/ane.0000000000001349] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Trafficking of anesthetic-sensitive receptors within the plasma membrane, or from one cellular component to another, occurs continuously. Changes in receptor trafficking have implications in altering anesthetic sensitivity. γ-Aminobutyric acid type A receptors (GABAARs) are anion-permeable ion channels and are the major class of receptor in the adult mammalian central nervous system that mediates inhibition. GABAergic signaling allows for precise synchronized firing of action potentials within brain circuits that is critical for cognition, behavior, and consciousness. This precision depends upon tightly controlled trafficking of GABAARs into the membrane. General anesthetics bind to and allosterically enhance GABAARs by prolonging the open state of the receptor and thereby altering neuronal and brain circuit activity. Subunit composition and GABAAR localization strongly influence anesthetic end points; therefore, changes in GABAAR trafficking could have significant consequences to anesthetic sensitivity. GABAARs are not static membrane structures but are in a constant state of flux between extrasynaptic and synaptic locations and are continually endocytosed and recycled from and to the membrane. Neuronal activity, posttranslational modifications, and some naturally occurring and synthetic compounds can influence the expression and trafficking of GABAARs. In this article, we review GABAARs, their trafficking, and how phosphorylation of GABAAR subunits can influence the surface expression and function of the receptor. Ultimately, alterations of GABAAR trafficking could modify anesthetic end points, both unintentionally through pathologic processes but potentially as a therapeutic target to adjust anesthetic-sensitive GABAARs.
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Affiliation(s)
- Thuy N Vien
- From the *Department of Neuroscience, Tufts University School of Medicine, Sackler School of Graduate Biomedical Sciences, Boston, Massachusetts; and †Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts
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General anesthetic actions on GABA A receptors in vivo are reduced in phospholipase C-related catalytically inactive protein knockout mice. J Anesth 2017; 31:531-538. [PMID: 28389811 DOI: 10.1007/s00540-017-2350-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/26/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE The aim of this study was to investigate the action of general anesthetics in phospholipase C-related catalytically inactive protein (PRIP)-knockout (KO) mice that alter GABAA receptor signaling. METHODS PRIP regulates the intracellular trafficking of β subunit-containing GABAA receptors in vitro. In this study, we examined the effects of intravenous anesthetics, propofol and etomidate that act via β subunit-containing GABAA receptors, in wild-type and Prip-KO mice. Mice were intraperitoneally injected with a drug, and a loss of righting reflex (LORR) assay and an electroencephalogram analysis were performed. RESULTS The cell surface expression of GABAA receptor β3 subunit detected by immunoblotting was decreased in Prip-knockout brain compared with that in wild-type brain without changing the expression of other GABAA receptor subunits. Propofol-treated Prip-KO mice exhibited significantly shorter duration of LORR and had lower total anesthetic score than wild-type mice in the LORR assay. The average duration of sleep time in an electroencephalogram analysis was shorter in propofol-treated Prip-KO mice than in wild-type mice. The hypnotic action of etomidate was also reduced in Prip-KO mice. However, ketamine, an NMDA receptor antagonist, had similar effects in the two genotypes. CONCLUSION PRIP regulates the cell surface expression of the GABAA receptor β3 subunit and modulates general anesthetic action in vivo. Elucidation of the involved regulatory mechanisms of GABAA receptor-dependent signaling would inform the development of safer anesthetic therapies for clinical applications.
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Wang B, Kundu M. Canonical and noncanonical functions of ULK/Atg1. Curr Opin Cell Biol 2017; 45:47-54. [PMID: 28292700 DOI: 10.1016/j.ceb.2017.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 02/07/2023]
Abstract
Mammalian Unc-51-like kinases 1 and 2 (ULK1 and ULK2) belong to the ULK/Atg1 family of serine/threonine kinases, which are conserved from yeast to mammals. Although ULK/Atg1 is best known for regulating flux through the autophagy pathway, it has evolutionarily conserved noncanonical functions in protein trafficking that are essential for maintaining cellular homeostasis. As a direct target of energy- and nutrient-sensing kinases, ULK/Atg1 is positioned to regulate the distribution and use of cellular resources in response to metabolic cues. In this review, we provide an overview of the molecular mechanisms through which ULK/Atg1 carries out its canonical and noncanonical functions and the signaling pathways that link its function to metabolism. We also highlight potential contributions of ULK/Atg1 in human diseases, including cancer and neurodegeneration.
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Affiliation(s)
- Bo Wang
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Mondira Kundu
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States.
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Stolz A, Putyrski M, Kutle I, Huber J, Wang C, Major V, Sidhu SS, Youle RJ, Rogov VV, Dötsch V, Ernst A, Dikic I. Fluorescence-based ATG8 sensors monitor localization and function of LC3/GABARAP proteins. EMBO J 2016; 36:549-564. [PMID: 28028054 DOI: 10.15252/embj.201695063] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/23/2016] [Accepted: 11/27/2016] [Indexed: 12/25/2022] Open
Abstract
Autophagy is a cellular surveillance pathway that balances metabolic and energy resources and transports specific cargos, including damaged mitochondria, other broken organelles, or pathogens for degradation to the lysosome. Central components of autophagosomal biogenesis are six members of the LC3 and GABARAP family of ubiquitin-like proteins (mATG8s). We used phage display to isolate peptides that possess bona fide LIR (LC3-interacting region) properties and are selective for individual mATG8 isoforms. Sensitivity of the developed sensors was optimized by multiplication, charge distribution, and fusion with a membrane recruitment (FYVE) or an oligomerization (PB1) domain. We demonstrate the use of the engineered peptides as intracellular sensors that recognize specifically GABARAP, GABL1, GABL2, and LC3C, as well as a bispecific sensor for LC3A and LC3B. By using an LC3C-specific sensor, we were able to monitor recruitment of endogenous LC3C to Salmonella during xenophagy, as well as to mitochondria during mitophagy. The sensors are general tools to monitor the fate of mATG8s and will be valuable in decoding the biological functions of the individual LC3/GABARAPs.
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Affiliation(s)
- Alexandra Stolz
- Institute of Biochemistry II Goethe University, Frankfurt am Main, Germany
| | - Mateusz Putyrski
- Institute of Biochemistry II Goethe University, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany
| | - Ivana Kutle
- Buchmann Institute for Molecular Life Sciences, Frankfurt am Main, Germany
| | - Jessica Huber
- Institute of Biophysical Chemistry, Goethe University, Frankfurt am Main, Germany
| | - Chunxin Wang
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Viktória Major
- Institute of Biochemistry II Goethe University, Frankfurt am Main, Germany
| | - Sachdev S Sidhu
- Banting and Best Department of Medical Research, The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Vladimir V Rogov
- Institute of Biophysical Chemistry, Goethe University, Frankfurt am Main, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry, Goethe University, Frankfurt am Main, Germany
| | - Andreas Ernst
- Institute of Biochemistry II Goethe University, Frankfurt am Main, Germany .,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany
| | - Ivan Dikic
- Institute of Biochemistry II Goethe University, Frankfurt am Main, Germany .,Buchmann Institute for Molecular Life Sciences, Frankfurt am Main, Germany
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A Highly Polymorphic Copy Number Variant in the NSF Gene is Associated with Cocaine Dependence. Sci Rep 2016; 6:31033. [PMID: 27498889 PMCID: PMC4976312 DOI: 10.1038/srep31033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/12/2016] [Indexed: 12/25/2022] Open
Abstract
Cocaine dependence is a complex psychiatric disorder involving both genetic and environmental factors. Several neurotransmitter systems mediate cocaine’s effects, dependence and relapse, being the components of the neurotransmitter release machinery good candidates for the disorder. Previously, we identified a risk haplotype for cocaine dependence in the NSF gene, encoding the protein N-Ethylmaleimide-Sensitive Factor essential for synaptic vesicle turnover. Here we examined the possible contribution to cocaine dependence of a large copy number variant (CNV) that encompasses part of the NSF gene. We performed a case-control association study in a discovery sample (359 cases and 356 controls) and identified an association between cocaine dependence and the CNV (P = 0.013), that was confirmed in the replication sample (508 cases and 569 controls, P = 7.1e-03) and in a pooled analysis (P = 1.8e-04), with an over-representation of low number of copies in cases. Subsequently, we studied the functional impact of the CNV on gene expression and found that the levels of two NSF transcripts were significantly increased in peripheral blood mononuclear cells (PBMC) along with the number of copies of the CNV. These results, together with a previous study from our group, support the role of NSF in the susceptibility to cocaine dependence.
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White spot syndrome virus entry is dependent on multiple endocytic routes and strongly facilitated by Cq-GABARAP in a CME-dependent manner. Sci Rep 2016; 6:28694. [PMID: 27385304 PMCID: PMC4935888 DOI: 10.1038/srep28694] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/08/2016] [Indexed: 12/13/2022] Open
Abstract
White spot syndrome virus (WSSV) is a lethal pathogen of shrimp and many other crustaceans, including crayfish. However, the molecular mechanism underlying its cellular entry remains elusive due to the lack of shrimp cell lines for viral propagation. Crayfish hematopoietic tissue (Hpt) cell culture was recently established as a good model for WSSV infection study. Here, we showed that multiple endocytic routes, including clathrin-mediated endocytosis (CME), macropinocytosis and caveolae-mediated endocytosis, were indispensably employed for the viral entry into Hpt cell of the crayfish Cherax quadricarinatus. Intriguingly, cellular autophagic activity was positively correlated with efficient viral entry, in which a key autophagy-related protein, γ-aminobutyric acid receptor-associated protein (Cq-GABARAP), that not only localized but also co-localized with WSSV on the Hpt cell membrane, strongly facilitated WSSV entry by binding to the viral envelope VP28 in a CME-dependent manner that was negatively regulated by Cq-Rac1. Furthermore, cytoskeletal components, including Cq-β-tubulin and Cq-β-actin, bound to both recombinant rCq-GABARAP and WSSV envelope proteins, which likely led to viral entry promotion via cooperation with rCq-GABARAP. Even under conditions that promoted viral entry, rCq-GABARAP significantly reduced viral replication at an early stage of infection, which was probably caused by the formation of WSSV aggregates in the cytoplasm.
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Nishizaki T. N-Ethylmaleimide Dissociates α7 ACh Receptor from a Complex with NSF and Promotes Its Delivery to the Presynaptic Membrane. Neurochem Res 2016; 41:2043-8. [PMID: 27105867 DOI: 10.1007/s11064-016-1915-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 11/29/2022]
Abstract
N-Ethylmaleimide (NEM)-sensitive factor (NSF) associates with soluble NSF attachment protein (SNAP), that binds to SNAP receptors (SNAREs) including syntaxin, SNAP25, and synaptobrevin. The complex of NSF/SNAP/SNAREs plays a critical role in the regulation of vesicular traffic. The present study investigated NEM-regulated α7 ACh receptor translocation. NSF associated with β-SNAP and the SNAREs syntaxin 1 and synaptobrevin 2 in the rat hippocampus. NSF also associated with the α7 ACh receptor subunit, the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1 and GluA2, and the γ-aminobutyric acid A (GABAA) receptor γ2 subunit. NEM, an inhibitor of NSF, significantly dissociated the α7 ACh receptor subunit from a complex with NSF and increased cell surface localization of the receptor subunit, but such effect was not obtained with the GluA1, GluA2 or γ2 subunits. NEM, alternatively, dissociated synaptobrevin 2 from an assembly of NSF/β-SNAP/syntaxin 1/synaptobrevin 2. NEM significantly increased the rate of nicotine-triggered AMPA receptor-mediated miniature excitatory postsynaptic currents, without affecting the amplitude, in rat hippocampal slices. The results of the present study indicate that NEM releases the α7 ACh receptor subunit and synaptobrevin 2 from an assembly of α7 ACh receptor subunit/NSF/β-SNAP/syntaxin 1/synaptobrevin 2, thereby promoting delivery of the α7 ACh receptor subunit to presynaptic membrane.
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Nakamura T, Arima-Yoshida F, Sakaue F, Nasu-Nishimura Y, Takeda Y, Matsuura K, Akshoomoff N, Mattson SN, Grossfeld PD, Manabe T, Akiyama T. PX-RICS-deficient mice mimic autism spectrum disorder in Jacobsen syndrome through impaired GABAA receptor trafficking. Nat Commun 2016; 7:10861. [PMID: 26979507 PMCID: PMC4799364 DOI: 10.1038/ncomms10861] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/27/2016] [Indexed: 11/09/2022] Open
Abstract
Jacobsen syndrome (JBS) is a rare congenital disorder caused by a terminal deletion of the long arm of chromosome 11. A subset of patients exhibit social behavioural problems that meet the diagnostic criteria for autism spectrum disorder (ASD); however, the underlying molecular pathogenesis remains poorly understood. PX-RICS is located in the chromosomal region commonly deleted in JBS patients with autistic-like behaviour. Here we report that PX-RICS-deficient mice exhibit ASD-like social behaviours and ASD-related comorbidities. PX-RICS-deficient neurons show reduced surface γ-aminobutyric acid type A receptor (GABAAR) levels and impaired GABAAR-mediated synaptic transmission. PX-RICS, GABARAP and 14-3-3ζ/θ form an adaptor complex that interconnects GABAAR and dynein/dynactin, thereby facilitating GABAAR surface expression. ASD-like behavioural abnormalities in PX-RICS-deficient mice are ameliorated by enhancing inhibitory synaptic transmission with a GABAAR agonist. Our findings demonstrate a critical role of PX-RICS in cognition and suggest a causal link between PX-RICS deletion and ASD-like behaviour in JBS patients.
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Affiliation(s)
- Tsutomu Nakamura
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Fumiko Arima-Yoshida
- Division of Neuronal Network, Department of Basic Medical Sciences, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Fumika Sakaue
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yukiko Nasu-Nishimura
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yasuko Takeda
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Ken Matsuura
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Natacha Akshoomoff
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Sarah N Mattson
- Department of Psychology, San Diego State University, San Diego, California 92120, USA
| | - Paul D Grossfeld
- Department of Pediatrics, School of Medicine, University of California, San Diego, San Diego, California 92123, USA
| | - Toshiya Manabe
- Division of Neuronal Network, Department of Basic Medical Sciences, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | - Tetsu Akiyama
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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Abstract
The Atg8 autophagy proteins are essential for autophagosome biogenesis and maturation. The γ-aminobutyric acid receptor-associated protein (GABARAP) Atg8 family is much less understood than the LC3 Atg8 family, and the relationship between the GABARAPs' previously identified roles as modulators of transmembrane protein trafficking and autophagy is not known. Here we report that GABARAPs recruit palmitoylated PI4KIIα, a lipid kinase that generates phosphatidylinositol 4-phosphate (PI4P) and binds GABARAPs, from the perinuclear Golgi region to autophagosomes to generate PI4P in situ. Depletion of either GABARAP or PI4KIIα, or overexpression of a dominant-negative kinase-dead PI4KIIα mutant, decreases autophagy flux by blocking autophagsome:lysosome fusion, resulting in the accumulation of abnormally large autophagosomes. The autophagosome defects are rescued by overexpressing PI4KIIα or by restoring intracellular PI4P through "PI4P shuttling." Importantly, PI4KIIα's role in autophagy is distinct from that of PI4KIIIβ and is independent of subsequent phosphatidylinositol 4,5 biphosphate (PIP2) generation. Thus, GABARAPs recruit PI4KIIα to autophagosomes, and PI4P generation on autophagosomes is critically important for fusion with lysosomes. Our results establish that PI4KIIα and PI4P are essential effectors of the GABARAP interactome's fusion machinery.
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Mathew S, Faheem M, Al-Malki AL, Kumosani TA, Qadri I. In silico inhibition of GABARAP activity using antiepileptic medicinal derived compounds. Bioinformation 2015; 11:189-95. [PMID: 26124559 PMCID: PMC4479051 DOI: 10.6026/97320630011189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 03/14/2015] [Indexed: 01/25/2023] Open
Abstract
Epilepsy is a neurological disorder affecting more than 50 million people worldwide. It can be controlled by antiepileptic drugs (AEDs) but more than 30% patients are still resistant to AEDs. To overcome this problem, researchers are trying to develop novel approaches to treat epilepsy including the use of herbal medicines. The γ-amino butyric acid type-A receptor associated protein (GABARAP) is ubiquitin-like modifier implicated in the intracellular trafficking of GABAAR. An in silico mutation was created at 116 amino acid position G116A, and an in silico study was carried out to identify the potential binding inhibitors (with antiepileptic properties) against the active sites of GABARAP. Five different plant derived compounds namely (a) Aconitine (b) Berberine (c) Montanine (d) Raubasine (e) Safranal were selected, and their quantitative structure-activity relationships (QSAR) have been conducted to search the inhibitory activity of the selected compounds. The results have shown maximum number of hydrogen bond (H-bond) interactions of Raubasine with highest interaction energy among all of the five compounds. So, Raubasine could be the best fit ligand of GABARAP but in vitro, and in vivo studies are necessary for further confirmation.
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Affiliation(s)
- Shilu Mathew
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, KSA
- Authors contributed equally
| | - Muhammad Faheem
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, KSA
- Authors contributed equally
| | | | - Taha A Kumosani
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, KSA
- Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, KSA
| | - Ishtiaq Qadri
- Medical Biotechnology and Translational Medicine Research, King Fahd Medical Research Center, King Abdul Aziz University, PO Box 80216 Jeddah 21589, Saudi Arabia
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Giant ankyrin-G stabilizes somatodendritic GABAergic synapses through opposing endocytosis of GABAA receptors. Proc Natl Acad Sci U S A 2014; 112:1214-9. [PMID: 25552561 DOI: 10.1073/pnas.1417989112] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
GABAA-receptor-based interneuron circuitry is essential for higher order function of the human nervous system and is implicated in schizophrenia, depression, anxiety disorders, and autism. Here we demonstrate that giant ankyrin-G (480-kDa ankyrin-G) promotes stability of somatodendritic GABAergic synapses in vitro and in vivo. Moreover, giant ankyrin-G forms developmentally regulated and cell-type-specific micron-scale domains within extrasynaptic somatodendritic plasma membranes of pyramidal neurons. We further find that giant ankyrin-G promotes GABAergic synapse stability through opposing endocytosis of GABAA receptors, and requires a newly described interaction with GABARAP, a GABAA receptor-associated protein. We thus present a new mechanism for stabilization of GABAergic interneuron synapses and micron-scale organization of extrasynaptic membrane that provides a rationale for studies linking ankyrin-G genetic variation with psychiatric disease and abnormal neurodevelopment.
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Lubbers BR, van Mourik Y, Schetters D, Smit AB, De Vries TJ, Spijker S. Prefrontal gamma-aminobutyric acid type A receptor insertion controls cue-induced relapse to nicotine seeking. Biol Psychiatry 2014; 76:750-8. [PMID: 24631130 DOI: 10.1016/j.biopsych.2014.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 01/16/2014] [Accepted: 02/04/2014] [Indexed: 12/17/2022]
Abstract
BACKGROUND Current smoking cessation therapies offer limited success, as relapse rates remain high. Nicotine, which is the major component of tobacco smoke, is thought to be primarily responsible for the addictive properties of tobacco. However, little is known about the molecular mechanisms underlying nicotine relapse, hampering development of more effective therapies. The objective of this study was to elucidate the role of medial prefrontal cortex (mPFC) glutamatergic and gamma-aminobutyric acid (GABA)ergic receptors in controlling relapse to nicotine seeking. METHODS Using an intravenous self-administration model, we studied glutamate and gamma-aminobutyric acid receptor regulation in the synaptic membrane fraction of the rat mPFC following extinction and cue-induced relapse to nicotine seeking. Subsequently, we locally intervened at the level of GABAergic signaling by using a mimetic peptide of the GABA receptor associated protein-interacting domain of GABA type A (GABAA) receptor subunit γ2 (TAT-GABAγ2) and muscimol, a GABAA receptor agonist. RESULTS Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and N-methyl-D-aspartate receptors were not regulated after the 30-min relapse test. However, GABAA receptor subunits α1 and γ2 were upregulated, and interference with GABAA receptor insertion in the cell membrane using the TAT-GABAγ2 peptide in the dorsal mPFC, but not the ventral mPFC, significantly increased responding during relapse. Increasing GABAA transmission with muscimol in the dorsal and ventral mPFC attenuated relapse. CONCLUSIONS These data indicate that cue-induced relapse entails a GABAergic plasticity mechanism that limits nicotine seeking by restoring inhibitory control in the dorsal mPFC. GABAA receptor-mediated neurotransmission in the dorsal mPFC constitutes a possible future therapeutic target for maintaining smoking abstinence.
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Affiliation(s)
- Bart R Lubbers
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam
| | - Yvar van Mourik
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Dustin Schetters
- Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam
| | - Taco J De Vries
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam; Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics & Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam.
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Comenencia-Ortiz E, Moss SJ, Davies PA. Phosphorylation of GABAA receptors influences receptor trafficking and neurosteroid actions. Psychopharmacology (Berl) 2014; 231:3453-65. [PMID: 24847959 PMCID: PMC4135009 DOI: 10.1007/s00213-014-3617-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 05/02/2014] [Indexed: 01/06/2023]
Abstract
RATIONALE Gamma-aminobutyric acid type A receptors (GABAARs) are the principal mediators of inhibitory transmission in the mammalian central nervous system. GABAARs can be localized at post-synaptic inhibitory specializations or at extrasynaptic sites. While synaptic GABAARs are activated transiently following the release of GABA from presynaptic vesicles, extrasynaptic GABAARs are typically activated continuously by ambient GABA concentrations and thus mediate tonic inhibition. The tonic inhibitory currents mediated by extrasynaptic GABAARs control neuronal excitability and the strength of synaptic transmission. However, the mechanisms by which neurons control the functional properties of extrasynaptic GABAARs had not yet been explored. OBJECTIVES We review GABAARs, how they are assembled and trafficked, and the role phosphorylation has on receptor insertion and membrane stabilization. Finally, we review the modulation of GABAARs by neurosteroids and how GABAAR phosphorylation can influence the actions of neurosteroids. CONCLUSIONS Trafficking and stability of functional channels to the membrane surface are critical for inhibitory efficacy. Phosphorylation of residues within GABAAR subunits plays an essential role in the assembly, trafficking, and cell surface stability of GABAARs. Neurosteroids are produced in the brain and are highly efficacious allosteric modulators of GABAAR-mediated current. This allosteric modulation by neurosteroids is influenced by the phosphorylated state of the GABAAR which is subunit dependent, adding temporal and regional variability to the neurosteroid response. Possible links between neurosteroid actions, phosphorylation, and GABAAR trafficking remain to be explored, but potential novel therapeutic targets may exist for numerous neurological and psychological disorders which are linked to fluctuations in neurosteroid levels and GABAA subunit expression.
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The kinesin KIF21B participates in the cell surface delivery of γ2 subunit-containing GABAA receptors. Eur J Cell Biol 2014; 93:338-46. [PMID: 25172774 DOI: 10.1016/j.ejcb.2014.07.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 07/18/2014] [Accepted: 07/21/2014] [Indexed: 01/15/2023] Open
Abstract
KIF21B, a kinesin family (KIF) protein, is a plus end-directed microtubule motor. The KIF21B gene is highly expressed in neuronal tissue and spleen and is a susceptibility locus for multiple sclerosis. KIF21B motility is regulated through TRIM3, a member of the cytoskeleton-associated-recycling or transport (CART) complex, involved in vesicular receptor recycling. Here we show that the GABAA receptor γ2-subunit co-precipitates and co-localizes with KIF21B in cultured hippocampal neurons. Knockdown of KIF21B gene expression through small hairpin (sh) RNA reduces the number of γ2-subunit-containing GABAA receptor (GABAARs) clusters in neurites and at the cell surface. Our data suggest that KIF21B participates in the delivery of GABAAR transport vesicles into dendrites.
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