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Tetenborg S, Ariakia F, Martinez-Soler E, Shihabeddin E, Lazart IC, Miller AC, O’Brien J. Trafficking of Connexin36 (Cx36) in the early secretory pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.25.586643. [PMID: 38585986 PMCID: PMC10996632 DOI: 10.1101/2024.03.25.586643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Gap junctions formed by the major neuronal connexin Cx36 function as electrical synapses in the nervous system and provide unique functions such as synchronizing activities or network oscillations. Although the physiological significance of electrical synapses for neuronal networks is well established, little is known about the pathways that regulate the transport of its main component: Cx36. Here we have used HEK293T cells as an expression system in combination with siRNA and BioID screens to study the transition of Cx36 from the ER to the cis Golgi. Our data indicate that the C-terminal tip of Cx36 is a key factor in this process, mediating binding interactions with two distinct components in the early secretory pathway: the COPII complex and the Golgi stacking protein Grasp55. The C-terminal amino acid valine serves as an ER export signal to recruit COPII cargo receptors Sec24A/B/C at ER exit sites, whereas the PDZ binding motif "SAYV" mediates an interaction with Grasp55. These two interactions have opposing effects in their respective compartments. While Sec24 subunits carry Cx36 out of the ER, Grasp55 stabilizes Cx36 in the Golgi as shown in over expression experiments. These early regulatory steps of Cx36 are expected to be essential for the formation, function, regulation and plasticity of electrical synapses in the developing and mature nervous system.
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Affiliation(s)
| | - Fatemeh Ariakia
- College of Optometry, University of Houston, Houston, TX, USA
- Contributed equally
| | | | - Eyad Shihabeddin
- College of Optometry, University of Houston, Houston, TX, USA
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Ignacio Cebrian Lazart
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Adam C. Miller
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, OR, USA
| | - John O’Brien
- College of Optometry, University of Houston, Houston, TX, USA
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Kersten N, Farías GG. A voyage from the ER: spatiotemporal insights into polarized protein secretion in neurons. Front Cell Dev Biol 2023; 11:1333738. [PMID: 38188013 PMCID: PMC10766823 DOI: 10.3389/fcell.2023.1333738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 12/04/2023] [Indexed: 01/09/2024] Open
Abstract
To function properly, neurons must maintain a proteome that differs in their somatodendritic and axonal domain. This requires the polarized sorting of newly synthesized secretory and transmembrane proteins into different vesicle populations as they traverse the secretory pathway. Although the trans-Golgi-network is generally considered to be the main sorting hub, this sorting process may already begin at the ER and continue through the Golgi cisternae. At each step in the sorting process, specificity is conferred by adaptors, GTPases, tethers, and SNAREs. Besides this, local synthesis and unconventional protein secretion may contribute to the polarized proteome to enable rapid responses to stimuli. For some transmembrane proteins, some of the steps in the sorting process are well-studied. These will be highlighted here. The universal rules that govern polarized protein sorting remain unresolved, therefore we emphasize the need to approach this problem in an unbiased, top-down manner. Unraveling these rules will contribute to our understanding of neuronal development and function in health and disease.
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Affiliation(s)
- Noortje Kersten
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Ginny G Farías
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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Polenghi M, Taverna E. Intracellular traffic and polarity in brain development. Front Neurosci 2023; 17:1172016. [PMID: 37859764 PMCID: PMC10583573 DOI: 10.3389/fnins.2023.1172016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 07/31/2023] [Indexed: 10/21/2023] Open
Abstract
Neurons forming the human brain are generated during embryonic development by neural stem and progenitor cells via a process called neurogenesis. A crucial feature contributing to neural stem cell morphological and functional heterogeneity is cell polarity, defined as asymmetric distribution of cellular components. Cell polarity is built and maintained thanks to the interplay between polarity proteins and polarity-generating organelles, such as the endoplasmic reticulum (ER) and the Golgi apparatus (GA). ER and GA affect the distribution of membrane components and work as a hub where glycans are added to nascent proteins and lipids. In the last decades our knowledge on the role of polarity in neural stem and progenitor cells have increased tremendously. However, the role of traffic and associated glycosylation in neural stem and progenitor cells is still relatively underexplored. In this review, we discuss the link between cell polarity, architecture, identity and intracellular traffic, and highlight how studies on neurons have shaped our knowledge and conceptual framework on traffic and polarity. We will then conclude by discussing how a group of rare diseases, called congenital disorders of glycosylation (CDG) offers the unique opportunity to study the contribution of traffic and glycosylation in the context of neurodevelopment.
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Toader C, Eva L, Covache-Busuioc RA, Costin HP, Glavan LA, Corlatescu AD, Ciurea AV. Unraveling the Multifaceted Role of the Golgi Apparatus: Insights into Neuronal Plasticity, Development, Neurogenesis, Alzheimer's Disease, and SARS-CoV-2 Interactions. Brain Sci 2023; 13:1363. [PMID: 37891732 PMCID: PMC10605100 DOI: 10.3390/brainsci13101363] [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: 08/01/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
This article critically evaluates the multifunctional role of the Golgi apparatus within neurological paradigms. We succinctly highlight its influence on neuronal plasticity, development, and the vital trafficking and sorting mechanisms for proteins and lipids. The discourse further navigates to its regulatory prominence in neurogenesis and its implications in Alzheimer's Disease pathogenesis. The emerging nexus between the Golgi apparatus and SARS-CoV-2 underscores its potential in viral replication processes. This consolidation accentuates the Golgi apparatus's centrality in neurobiology and its intersections with both neurodegenerative and viral pathologies. In essence, understanding the Golgi's multifaceted functions harbors profound implications for future therapeutic innovations in neurological and viral afflictions.
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Affiliation(s)
- Corneliu Toader
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
- Department of Vascular Neurosurgery, National Institute of Neurology and Neurovascular Diseases, 077160 Bucharest, Romania
| | - Lucian Eva
- Faculty of Medicine, “Dunarea de Jos” University of Galati, 800201 Galați, Romania
- Emergency Clinical Hospital “Prof. dr. N. Oblu”, 700309 Iasi, Romania
| | - Razvan-Adrian Covache-Busuioc
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
| | - Horia Petre Costin
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
| | - Luca-Andrei Glavan
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
| | - Antonio Daniel Corlatescu
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
| | - Alexandru Vlad Ciurea
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (H.P.C.); (L.-A.G.); (A.D.C.); (A.V.C.)
- Neurosurgery Department, Sanador Clinical Hospital, 010991 Bucharest, Romania
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Georgiev SV, Rizzoli SO. The long-loop recycling (LLR) of synaptic components as a question of economics. Mol Cell Neurosci 2023; 126:103862. [PMID: 37236414 DOI: 10.1016/j.mcn.2023.103862] [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: 02/28/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
The pre- and post-synaptic compartments contain a variety of molecules that are known to recycle between the plasma membrane and intracellular organelles. The recycling steps have been amply described in functional terms, with, for example, synaptic vesicle recycling being essential for neurotransmitter release, and postsynaptic receptor recycling being a fundamental feature of synaptic plasticity. However, synaptic protein recycling may also serve a more prosaic role, simply ensuring the repeated use of specific components, thereby minimizing the energy expenditure on the synthesis of synaptic proteins. This type of process has been recently described for components of the extracellular matrix, which undergo long-loop recycling (LLR), to and from the cell body. Here we suggest that the energy-saving recycling of synaptic components may be more widespread than is generally acknowledged, potentially playing a role in both synaptic vesicle protein usage and postsynaptic receptor metabolism.
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Affiliation(s)
- Svilen Veselinov Georgiev
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; International Max Planck Research School for Neuroscience, Göttingen, Germany.
| | - Silvio O Rizzoli
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, Göttingen, Germany.
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Maddison DC, Malik B, Amadio L, Bis-Brewer DM, Züchner S, Peters OM, Smith GA. COPI-regulated mitochondria-ER contact site formation maintains axonal integrity. Cell Rep 2023; 42:112883. [PMID: 37498742 PMCID: PMC10840514 DOI: 10.1016/j.celrep.2023.112883] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 06/05/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023] Open
Abstract
Coat protein complex I (COPI) is best known for its role in Golgi-endoplasmic reticulum (ER) trafficking, responsible for the retrograde transport of ER-resident proteins. The ER is crucial to neuronal function, regulating Ca2+ homeostasis and the distribution and function of other organelles such as endosomes, peroxisomes, and mitochondria via functional contact sites. Here we demonstrate that disruption of COPI results in mitochondrial dysfunction in Drosophila axons and human cells. The ER network is also disrupted, and the neurons undergo rapid degeneration. We demonstrate that mitochondria-ER contact sites (MERCS) are decreased in COPI-deficient axons, leading to Ca2+ dysregulation, heightened mitophagy, and a decrease in respiratory capacity. Reintroducing MERCS is sufficient to rescue not only mitochondrial distribution and Ca2+ uptake but also ER morphology, dramatically delaying neurodegeneration. This work demonstrates an important role for COPI-mediated trafficking in MERC formation, which is an essential process for maintaining axonal integrity.
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Affiliation(s)
- Daniel C Maddison
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Bilal Malik
- UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Leonardo Amadio
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK; UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Dana M Bis-Brewer
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Stephan Züchner
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Owen M Peters
- UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Gaynor A Smith
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK.
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Gould R, Brady S. Identifying mRNAs Residing in Myelinating Oligodendrocyte Processes as a Basis for Understanding Internode Autonomy. Life (Basel) 2023; 13:life13040945. [PMID: 37109474 PMCID: PMC10142070 DOI: 10.3390/life13040945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 04/07/2023] Open
Abstract
In elaborating and maintaining myelin sheaths on multiple axons/segments, oligodendrocytes distribute translation of some proteins, including myelin basic protein (MBP), to sites of myelin sheath assembly, or MSAS. As mRNAs located at these sites are selectively trapped in myelin vesicles during tissue homogenization, we performed a screen to identify some of these mRNAs. To confirm locations, we used real-time quantitative polymerase chain reaction (RT-qPCR), to measure mRNA levels in myelin (M) and ‘non-myelin’ pellet (P) fractions, and found that five (LPAR1, TRP53INP2, TRAK2, TPPP, and SH3GL3) of thirteen mRNAs were highly enriched in myelin (M/P), suggesting residences in MSAS. Because expression by other cell-types will increase p-values, some MSAS mRNAs might be missed. To identify non-oligodendrocyte expression, we turned to several on-line resources. Although neurons express TRP53INP2, TRAK2 and TPPP mRNAs, these expressions did not invalidate recognitions as MSAS mRNAs. However, neuronal expression likely prevented recognition of KIF1A and MAPK8IP1 mRNAs as MSAS residents and ependymal cell expression likely prevented APOD mRNA assignment to MSAS. Complementary in situ hybridization (ISH) is recommended to confirm residences of mRNAs in MSAS. As both proteins and lipids are synthesized in MSAS, understanding myelination should not only include efforts to identify proteins synthesized in MSAS, but also the lipids.
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Affiliation(s)
- Robert Gould
- Whitman Research Center, Marine Biology Laboratory, Woods Hole, MA 02543, USA
| | - Scott Brady
- Departments of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
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