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Pech U, Janssens J, Schoovaerts N, Kuenen S, Calatayud Aristoy C, Gallego SF, Makhzami S, Hulselmans GJ, Poovathingal S, Davie K, Bademosi AT, Swerts J, Vilain S, Aerts S, Verstreken P. Synaptic deregulation of cholinergic projection neurons causes olfactory dysfunction across five fly Parkinsonism models. eLife 2025; 13:RP98348. [PMID: 40178224 PMCID: PMC11968104 DOI: 10.7554/elife.98348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2025] Open
Abstract
The classical diagnosis of Parkinsonism is based on motor symptoms that are the consequence of nigrostriatal pathway dysfunction and reduced dopaminergic output. However, a decade prior to the emergence of motor issues, patients frequently experience non-motor symptoms, such as a reduced sense of smell (hyposmia). The cellular and molecular bases for these early defects remain enigmatic. To explore this, we developed a new collection of five fruit fly models of familial Parkinsonism and conducted single-cell RNA sequencing on young brains of these models. Interestingly, cholinergic projection neurons are the most vulnerable cells, and genes associated with presynaptic function are the most deregulated. Additional single nucleus sequencing of three specific brain regions of Parkinson's disease patients confirms these findings. Indeed, the disturbances lead to early synaptic dysfunction, notably affecting cholinergic olfactory projection neurons crucial for olfactory function in flies. Correcting these defects specifically in olfactory cholinergic interneurons in flies or inducing cholinergic signaling in Parkinson mutant human induced dopaminergic neurons in vitro using nicotine, both rescue age-dependent dopaminergic neuron decline. Hence, our research uncovers that one of the earliest indicators of disease in five different models of familial Parkinsonism is synaptic dysfunction in higher-order cholinergic projection neurons and this contributes to the development of hyposmia. Furthermore, the shared pathways of synaptic failure in these cholinergic neurons ultimately contribute to dopaminergic dysfunction later in life.
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Affiliation(s)
- Ulrike Pech
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Jasper Janssens
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
| | - Nils Schoovaerts
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Sabine Kuenen
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Carles Calatayud Aristoy
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Sandra F Gallego
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Samira Makhzami
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
| | - Gert J Hulselmans
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
| | - Suresh Poovathingal
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
- VIB-KU Leuven Center for Brain and Disease Research Technologies, Single Cell, Microfluidics and Bioinformatics Expertise UnitsLeuvenBelgium
| | - Kristofer Davie
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
- VIB-KU Leuven Center for Brain and Disease Research Technologies, Single Cell, Microfluidics and Bioinformatics Expertise UnitsLeuvenBelgium
| | - Adekunle T Bademosi
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Jef Swerts
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Sven Vilain
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
| | - Stein Aerts
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Human Genetics, Leuven Brain InstituteLeuvenBelgium
- VIB-KU Leuven Center for AI and Computational Biology (VIB.AI)LeuvenBelgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain and Disease ResearchLeuvenBelgium
- KU Leuven, Department of Neurosciences, Leuven Brain InstituteLeuvenBelgium
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2
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LaFoya B, Prehoda KE. Membrane oscillations driven by Arp2/3 constrict the intercellular bridge during neural stem cell divisions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.28.620743. [PMID: 39554021 PMCID: PMC11565815 DOI: 10.1101/2024.10.28.620743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/19/2024]
Abstract
After the first furrowing step of animal cell division, the nascent sibling cells remain connected by a thin intercellular bridge (ICB). In isolated cells nascent siblings migrate away from each other to generate tension and constrict the ICB, but less is known about how cells complete cytokinesis when constrained within tissues. We examined the ICBs formed by Drosophila larval brain neural stem cell (NSC) asymmetric divisions and find that they rely on constriction focused at the central midbody region rather than the flanking arms of isolated cell ICBs. Super-resolution, full volume imaging revealed unexpected oscillatory waves in plasma membrane sheets surrounding the ICB pore during its formation and constriction. We find that these membrane dynamics are driven by Arp2/3-dependent branched actin networks. Inhibition of Arp2/3 complex activity blocks membrane oscillations and prevents ICB formation and constriction. Our results identify a previously unrecognized role for localized membrane oscillations in ICB function when cells cannot generate tension through migration.
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Affiliation(s)
- Bryce LaFoya
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, 1229 University of Oregon, Eugene, OR 97403
| | - Kenneth E. Prehoda
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, 1229 University of Oregon, Eugene, OR 97403
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3
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Tillu VA, Redpath GMI, Rae J, Ruan J, Yao Y, Cagigas ML, Whan R, Hardeman EC, Gunning PW, Ananthanarayanan V, Parton RG, Ariotti N. Precision in situ cryogenic correlative light and electron microscopy of optogenetically positioned organelles. J Cell Sci 2024; 137:jcs262163. [PMID: 39308425 DOI: 10.1242/jcs.262163] [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: 03/27/2024] [Accepted: 09/12/2024] [Indexed: 11/01/2024] Open
Abstract
Unambiguous targeting of cellular structures for in situ cryo-electron microscopy in the heterogeneous, dense and compacted environment of the cytoplasm remains challenging. Here, we have developed a cryogenic correlative light and electron microscopy (cryo-CLEM) workflow that utilizes thin cells grown on a mechanically defined substratum for rapid analysis of organelles and macromolecular complexes by cryo-electron tomography (cryo-ET). We coupled these advancements with optogenetics to redistribute perinuclear-localised organelles to the cell periphery, allowing visualisation of organelles that would otherwise be positioned in cellular regions too thick for cryo-ET. This reliable and robust workflow allows for fast in situ analyses without the requirement for cryo-focused ion beam milling. Using this protocol, cells can be frozen, imaged by cryo-fluorescence microscopy and be ready for batch cryo-ET within a day.
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Affiliation(s)
- Vikas A Tillu
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland 4072, Australia
| | - Gregory M I Redpath
- EMBL Australia Node in Single Molecule Science , School of Medical Sciences, University of New South Wales Sydney, New South Wales 2033, Australia
| | - James Rae
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland 4072, Australia
| | - Juanfang Ruan
- University of New South Wales Sydney, Electron Microscope Unit , Mark Wainwright Analytical Centre, Sydney, New South Wales 2033, Australia
| | - Yin Yao
- University of New South Wales Sydney, Electron Microscope Unit , Mark Wainwright Analytical Centre, Sydney, New South Wales 2033, Australia
| | - Maria L Cagigas
- University of New South Wales Sydney, School of Medical Sciences , Kensington, Sydney, New South Wales 2033, Australia
| | - Renee Whan
- University of New South Wales Sydney, Katharina Gaus Light Microscopy Facility , Mark Wainwright Analytical Centre, Sydney, New South Wales 2033, Australia
| | - Edna C Hardeman
- University of New South Wales Sydney, School of Medical Sciences , Kensington, Sydney, New South Wales 2033, Australia
| | - Peter W Gunning
- University of New South Wales Sydney, School of Medical Sciences , Kensington, Sydney, New South Wales 2033, Australia
| | - Vaishnavi Ananthanarayanan
- EMBL Australia Node in Single Molecule Science , School of Medical Sciences, University of New South Wales Sydney, New South Wales 2033, Australia
| | - Robert G Parton
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland 4072, Australia
- The University of Queensland, Centre for Microscopy and Microanalysis, Brisbane, Queensland 4072, Australia
| | - Nicholas Ariotti
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Queensland 4072, Australia
- University of New South Wales Sydney, Electron Microscope Unit , Mark Wainwright Analytical Centre, Sydney, New South Wales 2033, Australia
- University of New South Wales Sydney, School of Medical Sciences , Kensington, Sydney, New South Wales 2033, Australia
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Wu Z, Du Y, Kirchhausen T, He K. Probing and imaging phospholipid dynamics in live cells. LIFE METABOLISM 2024; 3:loae014. [PMID: 39872507 PMCID: PMC11749120 DOI: 10.1093/lifemeta/loae014] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 03/30/2024] [Accepted: 04/11/2024] [Indexed: 01/30/2025]
Abstract
Distinct phospholipid species display specific distribution patterns across cellular membranes, which are important for their structural and signaling roles and for preserving the integrity and functionality of the plasma membrane and organelles. Recent advancements in lipid biosensor technology and imaging modalities now allow for direct observation of phospholipid distribution, trafficking, and dynamics in living cells. These innovations have markedly advanced our understanding of phospholipid function and regulation at both cellular and subcellular levels. Herein, we summarize the latest developments in phospholipid biosensor design and application, emphasizing the contribution of cutting-edge imaging techniques to elucidating phospholipid dynamics and distribution with unparalleled spatiotemporal precision.
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Affiliation(s)
- Zhongsheng Wu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongtao Du
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, United States
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, United States
| | - Kangmin He
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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5
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Jacquemyn J, Kuenen S, Swerts J, Pavie B, Vijayan V, Kilic A, Chabot D, Wang YC, Schoovaerts N, Corthout N, Verstreken P. Parkinsonism mutations in DNAJC6 cause lipid defects and neurodegeneration that are rescued by Synj1. NPJ Parkinsons Dis 2023; 9:19. [PMID: 36739293 PMCID: PMC9899244 DOI: 10.1038/s41531-023-00459-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 01/16/2023] [Indexed: 02/06/2023] Open
Abstract
Recent evidence links dysfunctional lipid metabolism to the pathogenesis of Parkinson's disease, but the mechanisms are not resolved. Here, we generated a new Drosophila knock-in model of DNAJC6/Auxilin and find that the pathogenic mutation causes synaptic dysfunction, neurological defects and neurodegeneration, as well as specific lipid metabolism alterations. In these mutants, membrane lipids containing long-chain polyunsaturated fatty acids, including phosphatidylinositol lipid species that are key for synaptic vesicle recycling and organelle function, are reduced. Overexpression of another protein mutated in Parkinson's disease, Synaptojanin-1, known to bind and metabolize specific phosphoinositides, rescues the DNAJC6/Auxilin lipid alterations, the neuronal function defects and neurodegeneration. Our work reveals a functional relation between two proteins mutated in Parkinsonism and implicates deregulated phosphoinositide metabolism in the maintenance of neuronal integrity and neuronal survival.
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Affiliation(s)
- Julie Jacquemyn
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- Neuroscience and Mental Health Institute, University of Alberta, Department of Physiology, Department of Cell Biology, Group on Molecular and Cell Biology of Lipids, Edmonton, Alberta, Canada
| | - Sabine Kuenen
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Jef Swerts
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Benjamin Pavie
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB-Bioimaging Core, 3000, Leuven, Belgium
| | - Vinoy Vijayan
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Ayse Kilic
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Dries Chabot
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Yu-Chun Wang
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB Technology Watch, Technology Innovation Laboratory, VIB, Gent, Belgium
| | - Nils Schoovaerts
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Nikky Corthout
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB-Bioimaging Core, 3000, Leuven, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium.
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium.
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6
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Stojilkovic SS, Balla T. PI(4,5)P2-dependent and -independent roles of PI4P in the control of hormone secretion by pituitary cells. Front Endocrinol (Lausanne) 2023; 14:1118744. [PMID: 36777340 PMCID: PMC9911653 DOI: 10.3389/fendo.2023.1118744] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 01/03/2023] [Indexed: 01/28/2023] Open
Abstract
Plasma membrane and organelle membranes are home to seven phosphoinositides, an important class of low-abundance anionic signaling lipids that contribute to cellular functions by recruiting cytoplasmic proteins or interacting with the cytoplasmic domains of membrane proteins. Here, we briefly review the functions of three phosphoinositides, PI4P, PI(4,5)P2, and PI(3,4,5)P3, in cellular signaling and exocytosis, focusing on hormone-producing pituitary cells. PI(4,5)P2, acting as a substrate for phospholipase C, plays a key role in the control of pituitary cell functions, including hormone synthesis and secretion. PI(4,5)P2 also acts as a substrate for class I PI3-kinases, leading to the generation of two intracellular messengers, PI(3,4,5)P3 and PI(3,4)P2, which act through their intracellular effectors, including Akt. PI(4,5)P2 can also influence the release of pituitary hormones acting as an intact lipid to regulate ion channel gating and concomitant calcium signaling, as well as the exocytic pathway. Recent findings also show that PI4P is not only a precursor of PI(4,5)P2, but also a key signaling molecule in many cell types, including pituitary cells, where it controls hormone secretion in a PI(4,5)P2-independent manner.
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Affiliation(s)
- Stanko S. Stojilkovic
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Stanko S. Stojilkovic,
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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7
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Somberg NH, Wu WW, Medeiros-Silva J, Dregni AJ, Jo H, DeGrado WF, Hong M. SARS-CoV-2 Envelope Protein Forms Clustered Pentamers in Lipid Bilayers. Biochemistry 2022; 61:2280-2294. [PMID: 36219675 PMCID: PMC9583936 DOI: 10.1021/acs.biochem.2c00464] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/26/2022] [Indexed: 11/30/2022]
Abstract
The SARS-CoV-2 envelope (E) protein is a viroporin associated with the acute respiratory symptoms of COVID-19. E forms cation-selective ion channels that assemble in the lipid membrane of the endoplasmic reticulum Golgi intermediate compartment. The channel activity of E is linked to the inflammatory response of the host cell to the virus. Like many viroporins, E is thought to oligomerize with a well-defined stoichiometry. However, attempts to determine the E stoichiometry have led to inconclusive results and suggested mixtures of oligomers whose exact nature might vary with the detergent used. Here, we employ 19F solid-state nuclear magnetic resonance and the centerband-only detection of exchange (CODEX) technique to determine the oligomeric number of E's transmembrane domain (ETM) in lipid bilayers. The CODEX equilibrium value, which corresponds to the inverse of the oligomeric number, indicates that ETM assembles into pentamers in lipid bilayers, without any detectable fraction of low-molecular-weight oligomers. Unexpectedly, at high peptide concentrations and in the presence of the lipid phosphatidylinositol, the CODEX data indicate that more than five 19F spins are within a detectable distance of about 2 nm, suggesting that the ETM pentamers cluster in the lipid bilayer. Monte Carlo simulations that take into account peptide-peptide and peptide-lipid interactions yielded pentamer clusters that reproduced the CODEX data. This supramolecular organization is likely important for E-mediated virus assembly and budding and for the channel function of the protein.
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Affiliation(s)
- Noah H Somberg
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts02139, United States
| | - Westley W Wu
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts02139, United States
| | - João Medeiros-Silva
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts02139, United States
| | - Aurelio J Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts02139, United States
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, 555 Mission Bay Blvd. South, San Francisco, California94158, United States
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, 555 Mission Bay Blvd. South, San Francisco, California94158, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts02139, United States
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Vardar G, Salazar-Lázaro A, Zobel S, Trimbuch T, Rosenmund C. Syntaxin-1A modulates vesicle fusion in mammalian neurons via juxtamembrane domain dependent palmitoylation of its transmembrane domain. eLife 2022; 11:78182. [PMID: 35638903 PMCID: PMC9183232 DOI: 10.7554/elife.78182] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/30/2022] [Indexed: 11/16/2022] Open
Abstract
SNAREs are undoubtedly one of the core elements of synaptic transmission. Contrary to the well characterized function of their SNARE domains bringing the plasma and vesicular membranes together, the level of contribution of their juxtamembrane domain (JMD) and the transmembrane domain (TMD) to the vesicle fusion is still under debate. To elucidate this issue, we analyzed three groups of STX1A mutations in cultured mouse hippocampal neurons: (1) elongation of STX1A’s JMD by three amino acid insertions in the junction of SNARE-JMD or JMD-TMD; (2) charge reversal mutations in STX1A’s JMD; and (3) palmitoylation deficiency mutations in STX1A’s TMD. We found that both JMD elongations and charge reversal mutations have position-dependent differential effects on Ca2+-evoked and spontaneous neurotransmitter release. Importantly, we show that STX1A’s JMD regulates the palmitoylation of STX1A’s TMD and loss of STX1A palmitoylation either through charge reversal mutation K260E or by loss of TMD cysteines inhibits spontaneous vesicle fusion. Interestingly, the retinal ribbon specific STX3B has a glutamate in the position corresponding to the K260E mutation in STX1A and mutating it with E259K acts as a molecular on-switch. Furthermore, palmitoylation of post-synaptic STX3A can be induced by the exchange of its JMD with STX1A’s JMD together with the incorporation of two cysteines into its TMD. Forced palmitoylation of STX3A dramatically enhances spontaneous vesicle fusion suggesting that STX1A regulates spontaneous release through two distinct mechanisms: one through the C-terminal half of its SNARE domain and the other through the palmitoylation of its TMD.
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Affiliation(s)
- Gülçin Vardar
- Department of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andrea Salazar-Lázaro
- Department of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Sina Zobel
- Department of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Thorsten Trimbuch
- Department of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Christian Rosenmund
- Department of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Doumane M, Caillaud MC, Jaillais Y. Experimental manipulation of phosphoinositide lipids: from cells to organisms. Trends Cell Biol 2022; 32:445-461. [DOI: 10.1016/j.tcb.2022.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/14/2022]
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10
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Barak-Broner N, Singer-Lahat D, Chikvashvili D, Lotan I. CK2 Phosphorylation Is Required for Regulation of Syntaxin 1A Activity in Ca 2+-Triggered Release in Neuroendocrine Cells. Int J Mol Sci 2021; 22:ijms222413556. [PMID: 34948351 PMCID: PMC8708312 DOI: 10.3390/ijms222413556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/12/2021] [Accepted: 12/13/2021] [Indexed: 12/29/2022] Open
Abstract
The polybasic juxtamembrane region (5RK) of the plasma membrane neuronal SNARE, syntaxin1A (Syx), was previously shown by us to act as a fusion clamp in PC12 cells, as charge neutralization of 5RK promotes spontaneous and inhibits Ca2+-triggered release. Using a Syx-based FRET probe (CSYS), we demonstrated that 5RK is required for a depolarization-induced Ca+2-dependent opening (close-to-open transition; CDO) of Syx, which involves the vesicular SNARE synaptobrevin2 and occurs concomitantly with Ca2+-triggered release. Here, we investigated the mechanism underlying the CDO requirement for 5RK and identified phosphorylation of Syx at Ser-14 (S14) by casein kinase 2 (CK2) as a crucial molecular determinant. Thus, following biochemical verification that both endogenous Syx and CSYS are constitutively S14 phosphorylated in PC12 cells, dynamic FRET analysis of phospho-null and phospho-mimetic mutants of CSYS and the use of a CK2 inhibitor revealed that the S14 phosphorylation confers the CDO requirement for 5RK. In accord, amperometric analysis of catecholamine release revealed that the phospho-null mutant does not support Ca2+-triggered release. These results identify a functionally important CK2 phosphorylation of Syx that is required for the 5RK-regulation of CDO and for concomitant Ca2+-triggered release. Further, also spontaneous release, conferred by charge neutralization of 5RK, was abolished in the phospho-null mutant.
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Affiliation(s)
- Noa Barak-Broner
- Department of Neurobiology Biochemistry & Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel;
| | - Dafna Singer-Lahat
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
| | - Dodo Chikvashvili
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
| | - Ilana Lotan
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
- Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel
- Correspondence:
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11
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Munc18-dependent and -independent clustering of syntaxin in the plasma membrane of cultured endocrine cells. Proc Natl Acad Sci U S A 2021; 118:2025748118. [PMID: 34857632 DOI: 10.1073/pnas.2025748118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2021] [Indexed: 11/18/2022] Open
Abstract
Syntaxin helps in catalyzing membrane fusion during exocytosis. It also forms clusters in the plasma membrane, where both its transmembrane and SNARE domains are thought to homo-oligomerize. To study syntaxin clustering in live PC12 cells, we labeled granules with neuropeptide-Y-mCherry and syntaxin clusters with syntaxin-1a green fluorescent protein (GFP). Abundant clusters appeared under total internal reflection (TIRF) illumination, and some of them associated with granules ("on-granule clusters"). Syntaxin-1a-GFP or its mutants were expressed at low levels and competed with an excess of endogenous syntaxin for inclusion into clusters. On-granule inclusion was diminished by mutations known to inhibit binding to Munc18-1 in vitro. Knock-down of Munc18-1 revealed Munc18-dependent and -independent on-granule clustering. Clustering was inhibited by mutations expected to break salt bridges between syntaxin's Hb and SNARE domains and was rescued by additional mutations expected to restore them. Most likely, syntaxin is in a closed conformation when it clusters on granules, and its SNARE and Hb domains approach to within atomic distances. Pairwise replacements of Munc18-contacting residues with alanines had only modest effects, except that the pair R114A/I115A essentially abolished on-granule clustering. In summary, an on-granule cluster arises from the specific interaction between a granule and a dense cluster of syntaxin-Munc18-1 complexes. Off-granule clusters, by contrast, were resistant to even the strongest mutations we tried and required neither Munc18-1 nor the presence of a SNARE domain. They may well form through the nonstoichiometric interactions with membrane lipids that others have observed in cell-free systems.
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12
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Moro A, van Nifterick A, Toonen RF, Verhage M. Dynamin controls neuropeptide secretion by organizing dense-core vesicle fusion sites. SCIENCE ADVANCES 2021; 7:eabf0659. [PMID: 34020952 PMCID: PMC8139595 DOI: 10.1126/sciadv.abf0659] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/02/2021] [Indexed: 05/13/2023]
Abstract
Synaptic vesicles (SVs) release neurotransmitters at specialized active zones, but release sites and organizing principles for the other major secretory pathway, neuropeptide/neuromodulator release from dense-core vesicles (DCVs), remain elusive. We identify dynamins, yeast Vps1 orthologs, as DCV fusion site organizers in mammalian neurons. Genetic or pharmacological inactivation of all three dynamins strongly impaired DCV exocytosis, while SV exocytosis remained unaffected. Wild-type dynamin restored normal exocytosis but not guanosine triphosphatase-deficient or membrane-binding mutants that cause neurodevelopmental syndromes. During prolonged stimulation, repeated use of the same DCV fusion location was impaired in dynamin 1-3 triple knockout neurons. The syntaxin-1 staining efficiency, but not its expression level, was reduced. αSNAP (α-soluble N-ethylmaleimide-sensitive factor attachment protein) expression restored this. We conclude that mammalian dynamins organize DCV fusion sites, downstream of αSNAP, by regulating the equilibrium between fusogenic and non-fusogenic syntaxin-1 promoting its availability for SNARE (SNAP receptor) complex formation and DCV exocytosis.
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Affiliation(s)
- Alessandro Moro
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Medical Center, Amsterdam, Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
| | - Anne van Nifterick
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands.
| | - Matthijs Verhage
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Medical Center, Amsterdam, Netherlands.
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
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13
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Castroflorio E, den Hoed J, Svistunova D, Finelli MJ, Cebrian-Serrano A, Corrochano S, Bassett AR, Davies B, Oliver PL. The Ncoa7 locus regulates V-ATPase formation and function, neurodevelopment and behaviour. Cell Mol Life Sci 2021; 78:3503-3524. [PMID: 33340069 PMCID: PMC8038996 DOI: 10.1007/s00018-020-03721-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/08/2020] [Accepted: 11/24/2020] [Indexed: 02/08/2023]
Abstract
Members of the Tre2/Bub2/Cdc16 (TBC), lysin motif (LysM), domain catalytic (TLDc) protein family are associated with multiple neurodevelopmental disorders, although their exact roles in disease remain unclear. For example, nuclear receptor coactivator 7 (NCOA7) has been associated with autism, although almost nothing is known regarding the mode-of-action of this TLDc protein in the nervous system. Here we investigated the molecular function of NCOA7 in neurons and generated a novel mouse model to determine the consequences of deleting this locus in vivo. We show that NCOA7 interacts with the cytoplasmic domain of the vacuolar (V)-ATPase in the brain and demonstrate that this protein is required for normal assembly and activity of this critical proton pump. Neurons lacking Ncoa7 exhibit altered development alongside defective lysosomal formation and function; accordingly, Ncoa7 deletion animals exhibited abnormal neuronal patterning defects and a reduced expression of lysosomal markers. Furthermore, behavioural assessment revealed anxiety and social defects in mice lacking Ncoa7. In summary, we demonstrate that NCOA7 is an important V-ATPase regulatory protein in the brain, modulating lysosomal function, neuronal connectivity and behaviour; thus our study reveals a molecular mechanism controlling endolysosomal homeostasis that is essential for neurodevelopment.
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Affiliation(s)
| | - Joery den Hoed
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Daria Svistunova
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Mattéa J Finelli
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | | | - Silvia Corrochano
- MRC Harwell Institute, Harwell Campus, Oxfordshire, OX11 0RD, UK
- Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos, Calle del Prof Martín Lagos s/n, 28040, Madrid, Spain
| | - Andrew R Bassett
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Benjamin Davies
- Wellcome Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Peter L Oliver
- MRC Harwell Institute, Harwell Campus, Oxfordshire, OX11 0RD, UK.
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK.
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14
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Ernest James Phillips T, Maguire E. Phosphoinositides: Roles in the Development of Microglial-Mediated Neuroinflammation and Neurodegeneration. Front Cell Neurosci 2021; 15:652593. [PMID: 33841102 PMCID: PMC8032904 DOI: 10.3389/fncel.2021.652593] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/08/2021] [Indexed: 12/11/2022] Open
Abstract
Microglia are increasingly recognized as vital players in the pathology of a variety of neurodegenerative conditions including Alzheimer’s (AD) and Parkinson’s (PD) disease. While microglia have a protective role in the brain, their dysfunction can lead to neuroinflammation and contributes to disease progression. Also, a growing body of literature highlights the seven phosphoinositides, or PIPs, as key players in the regulation of microglial-mediated neuroinflammation. These small signaling lipids are phosphorylated derivates of phosphatidylinositol, are enriched in the brain, and have well-established roles in both homeostasis and disease.Disrupted PIP levels and signaling has been detected in a variety of dementias. Moreover, many known AD disease modifiers identified via genetic studies are expressed in microglia and are involved in phospholipid metabolism. One of these, the enzyme PLCγ2 that hydrolyzes the PIP species PI(4,5)P2, displays altered expression in AD and PD and is currently being investigated as a potential therapeutic target.Perhaps unsurprisingly, neurodegenerative conditions exhibiting PIP dyshomeostasis also tend to show alterations in aspects of microglial function regulated by these lipids. In particular, phosphoinositides regulate the activities of proteins and enzymes required for endocytosis, toll-like receptor signaling, purinergic signaling, chemotaxis, and migration, all of which are affected in a variety of neurodegenerative conditions. These functions are crucial to allow microglia to adequately survey the brain and respond appropriately to invading pathogens and other abnormalities, including misfolded proteins. AD and PD therapies are being developed to target many of the above pathways, and although not yet investigated, simultaneous PIP manipulation might enhance the beneficial effects observed. Currently, only limited therapeutics are available for dementia, and although these show some benefits for symptom severity and progression, they are far from curative. Given the importance of microglia and PIPs in dementia development, this review summarizes current research and asks whether we can exploit this information to design more targeted, or perhaps combined, dementia therapeutics. More work is needed to fully characterize the pathways discussed in this review, but given the strength of the current literature, insights in this area could be invaluable for the future of neurodegenerative disease research.
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Affiliation(s)
| | - Emily Maguire
- UK Dementia Research Institute at Cardiff University, Cardiff, United Kingdom
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15
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Li TN, Chen YJ, Lu TY, Wang YT, Lin HC, Yao CK. A positive feedback loop between Flower and PI(4,5)P 2 at periactive zones controls bulk endocytosis in Drosophila. eLife 2020; 9:60125. [PMID: 33300871 PMCID: PMC7748424 DOI: 10.7554/elife.60125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/09/2020] [Indexed: 01/01/2023] Open
Abstract
Synaptic vesicle (SV) endocytosis is coupled to exocytosis to maintain SV pool size and thus neurotransmitter release. Intense stimulation induces activity-dependent bulk endocytosis (ADBE) to recapture large quantities of SV constituents in large endosomes from which SVs reform. How these consecutive processes are spatiotemporally coordinated remains unknown. Here, we show that Flower Ca2+ channel-dependent phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) compartmentalization governs control of these processes in Drosophila. Strong stimuli trigger PI(4,5)P2 microdomain formation at periactive zones. Upon exocytosis, Flower translocates from SVs to periactive zones, where it increases PI(4,5)P2 levels via Ca2+ influxes. Remarkably, PI(4,5)P2 directly enhances Flower channel activity, thereby establishing a positive feedback loop for PI(4,5)P2 microdomain compartmentalization. PI(4,5)P2 microdomains drive ADBE and SV reformation from bulk endosomes. PI(4,5)P2 further retrieves Flower to bulk endosomes, terminating endocytosis. We propose that the interplay between Flower and PI(4,5)P2 is the crucial spatiotemporal cue that couples exocytosis to ADBE and subsequent SV reformation.
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Affiliation(s)
- Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Jung Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ting-Yi Lu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - You-Tung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
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16
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Voleti R, Jaczynska K, Rizo J. Ca 2+-dependent release of synaptotagmin-1 from the SNARE complex on phosphatidylinositol 4,5-bisphosphate-containing membranes. eLife 2020; 9:57154. [PMID: 32808925 PMCID: PMC7498268 DOI: 10.7554/elife.57154] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 08/12/2020] [Indexed: 11/13/2022] Open
Abstract
The Ca2+ sensor synaptotagmin-1 and the SNARE complex cooperate to trigger neurotransmitter release. Structural studies elucidated three distinct synaptotagmin-1-SNARE complex binding modes involving 'polybasic', 'primary' and 'tripartite' interfaces of synaptotagmin-1. We investigated these interactions using NMR and fluorescence spectroscopy. Synaptotagmin-1 binds to the SNARE complex through the polybasic and primary interfaces in solution. Ca2+-free synaptotagmin-1 binds to SNARE complexes anchored on PIP2-containing nanodiscs. R398Q/R399Q and E295A/Y338W mutations at the primary interface, which strongly impair neurotransmitter release, disrupt and enhance synaptotagmin-1-SNARE complex binding, respectively. Ca2+ induces tight binding of synaptotagmin-1 to PIP2-containing nanodiscs, disrupting synaptotagmin-1-SNARE interactions. Specific effects of mutations in the polybasic region on Ca2+-dependent synaptotagmin-1-PIP2-membrane interactions correlate with their effects on release. Our data suggest that synaptotagmin-1 binds to the SNARE complex through the primary interface and that Ca2+ releases this interaction, inducing PIP2/membrane binding and allowing cooperation between synaptotagmin-1 and the SNAREs in membrane fusion to trigger release.
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Affiliation(s)
- Rashmi Voleti
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Klaudia Jaczynska
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
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17
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Li M, Oh TJ, Fan H, Diao J, Zhang K. Syntaxin Clustering and Optogenetic Control for Synaptic Membrane Fusion. J Mol Biol 2020; 432:4773-4782. [PMID: 32682743 DOI: 10.1016/j.jmb.2020.07.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/05/2020] [Accepted: 07/12/2020] [Indexed: 01/01/2023]
Abstract
Membrane fusion during synaptic transmission mediates the trafficking of chemical signals and neuronal communication. The fast kinetics of membrane fusion on the order of millisecond is precisely regulated by the assembly of SNAREs and accessory proteins. It is believed that the formation of the SNARE complex is a key step during membrane fusion. Little is known, however, about the molecular machinery that mediates the formation of a large pre-fusion complex, including multiple SNAREs and accessory proteins. Syntaxin, a transmembrane protein on the plasma membrane, has been observed to undergo oligomerization to form clusters. Whether this clustering plays a critical role in membrane fusion is poorly understood in live cells. Optogenetics is an emerging biotechnology armed with the capacity to precisely modulate protein-protein interaction in time and space. Here, we propose an experimental scheme that combines optogenetics with single-vesicle membrane fusion, aiming to gain a better understanding of the molecular mechanism by which the syntaxin cluster regulates membrane fusion. We envision that newly developed optogenetic tools could facilitate the mechanistic understanding of synaptic transmission in live cells and animals.
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Affiliation(s)
- Miaoling Li
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Teak-Jung Oh
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Huaxun Fan
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
| | - Kai Zhang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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18
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Deák F, Anderson RE, Fessler JL, Sherry DM. Novel Cellular Functions of Very Long Chain-Fatty Acids: Insight From ELOVL4 Mutations. Front Cell Neurosci 2019; 13:428. [PMID: 31616255 PMCID: PMC6763723 DOI: 10.3389/fncel.2019.00428] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 09/06/2019] [Indexed: 12/22/2022] Open
Abstract
Elongation of Very Long chain fatty acids-4 (ELOVL4) protein is a member of the ELOVL family of fatty acid elongases that is collectively responsible for catalyzing formation of long chain fatty acids. ELOVL4 is the only family member that catalyzes production of Very Long Chain Saturated Fatty Acids (VLC-SFA) and Very Long Chain Polyunsaturated Fatty Acids (VLC-PUFA) with chain lengths ≥28 carbons. ELOVL4 and its VLC-SFA and VLC-PUFA products are emerging as important regulators of synaptic signaling and neuronal survival in the central nervous system (CNS). Distinct sets of mutations in ELOVL4 cause three different neurological diseases in humans. Heterozygous inheritance of one set of autosomal dominant ELOVL4 mutations that leads to truncation of the ELOVL4 protein causes Stargardt-like macular dystrophy (STGD3), an aggressive juvenile-onset retinal degeneration. Heterozygous inheritance of a different set of autosomal dominant ELOVL4 mutations that leads to a full-length protein with single amino acid substitutions causes spinocerebellar ataxia 34 (SCA34), a late-onset neurodegenerative disease characterized by gait ataxia and cerebellar atrophy. Homozygous inheritance of a different set of ELOVL4 mutations causes a more severe disease with infantile onset characterized by seizures, spasticity, intellectual disability, ichthyosis, and premature death. ELOVL4 is expressed widely in the CNS and is found primarily in neurons. ELOVL4 is expressed in cell-specific patterns within different regions of the CNS that are likely to be related to disease symptoms. In the retina, ELOVL4 is expressed exclusively in photoreceptors and produces VLC-PUFA that are incorporated into phosphatidylcholine and enriched in the light sensitive membrane disks of the photoreceptor outer segments. VLC-PUFA are enzymatically converted into "elovanoid" compounds that appear to provide paracrine signals that promote photoreceptor and neuronal survival. In the brain, the main ELOVL4 products are VLC-SFA that are incorporated into sphingolipids and enriched in synaptic vesicles, where they regulate kinetics of presynaptic neurotransmitter release. Understanding the function of ELOVL4 and its VLC-SFA and VLC-PUFA products will advance our understanding of basic mechanisms in neural signaling and has potential for developing novel therapies for seizure and neurodegenerative diseases.
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Affiliation(s)
- Ferenc Deák
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Robert E Anderson
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Jennifer L Fessler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David M Sherry
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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19
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Hsp90 Mediates Membrane Deformation and Exosome Release. Mol Cell 2019; 71:689-702.e9. [PMID: 30193096 DOI: 10.1016/j.molcel.2018.07.016] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 06/18/2018] [Accepted: 07/13/2018] [Indexed: 12/21/2022]
Abstract
Hsp90 is an essential chaperone that guards proteome integrity and amounts to 2% of cellular protein. We now find that Hsp90 also has the ability to directly interact with and deform membranes via an evolutionarily conserved amphipathic helix. Using a new cell-free system and in vivo measurements, we show this amphipathic helix allows exosome release by promoting the fusion of multivesicular bodies (MVBs) with the plasma membrane. We dissect the relationship between Hsp90 conformation and membrane-deforming function and show that mutations and drugs that stabilize the open Hsp90 dimer expose the helix and allow MVB fusion, while these effects are blocked by the closed state. Hence, we structurally separated the Hsp90 membrane-deforming function from its well-characterized chaperone activity, and we show that this previously unrecognized function is required for exosome release.
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20
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Abstract
Polyphosphoinositides (PPIn) are essential signaling phospholipids that make remarkable contributions to the identity of all cellular membranes and signaling cascades in mammalian cells. They exert regulatory control over membrane homeostasis via selective interactions with cellular proteins at the membrane–cytoplasm interface. This review article briefly summarizes our current understanding of the key roles that PPIn play in orchestrating and regulating crucial electrical and chemical signaling events in mammalian neurons and the significant neuro-pathophysiological conditions that arise following alterations in their metabolism.
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Affiliation(s)
- Eamonn James Dickson
- Department Physiology and Membrane Biology, University of California, Davis, CA, 95616, USA
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21
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Padmanabhan P, Bademosi AT, Kasula R, Lauwers E, Verstreken P, Meunier FA. Need for speed: Super-resolving the dynamic nanoclustering of syntaxin-1 at exocytic fusion sites. Neuropharmacology 2019; 169:107554. [PMID: 30826343 DOI: 10.1016/j.neuropharm.2019.02.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/21/2019] [Accepted: 02/27/2019] [Indexed: 01/08/2023]
Abstract
Communication between cells relies on regulated exocytosis, a multi-step process that involves the docking, priming and fusion of vesicles with the plasma membrane, culminating in the release of neurotransmitters and hormones. Key proteins and lipids involved in exocytosis are subjected to Brownian movement and constantly switch between distinct motion states which are governed by short-lived molecular interactions. Critical biochemical reactions between exocytic proteins that occur in the confinement of nanodomains underpin the precise sequence of priming steps which leads to the fusion of vesicles. The advent of super-resolution microscopy techniques has provided the means to visualize individual molecules on the plasma membrane with high spatiotemporal resolution in live cells. These techniques are revealing a highly dynamic nature of the nanoscale organization of the exocytic machinery. In this review, we focus on soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) syntaxin-1, which mediates vesicular fusion. Syntaxin-1 is highly mobile at the plasma membrane, and its inherent speed allows fast assembly and disassembly of syntaxin-1 nanoclusters which are associated with exocytosis. We reflect on recent studies which have revealed the mechanisms regulating syntaxin-1 nanoclustering on the plasma membrane and draw inferences on the effect of synaptic activity, phosphoinositides, N-ethylmaleimide-sensitive factor (NSF), α-soluble NSF attachment protein (α-SNAP) and SNARE complex assembly on the dynamic nanoscale organization of syntaxin-1. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Pranesh Padmanabhan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Adekunle T Bademosi
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Ravikiran Kasula
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia
| | - Elsa Lauwers
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences and Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland, Australia.
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22
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Biochemical studies of membrane fusion at the single-particle level. Prog Lipid Res 2019; 73:92-100. [PMID: 30611882 DOI: 10.1016/j.plipres.2019.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 01/01/2019] [Accepted: 01/02/2019] [Indexed: 01/21/2023]
Abstract
To study membrane fusion mediated by synaptic proteins, proteoliposomes have been widely used for in vitro ensemble measurements with limited insights into the fusion mechanism. Single-particle techniques have proven to be powerful in overcoming the limitations of traditional ensemble methods. Here, we summarize current single-particle methods in biophysical and biochemical studies of fusion mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and other synaptic proteins, together with their advantages and limitations.
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23
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Wittig S, Haupt C, Hoffmann W, Kostmann S, Pagel K, Schmidt C. Oligomerisation of Synaptobrevin-2 Studied by Native Mass Spectrometry and Chemical Cross-Linking. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:149-160. [PMID: 29949059 PMCID: PMC6318248 DOI: 10.1007/s13361-018-2000-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/23/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Synaptobrevin-2 is a key player in signal transmission in neurons. It forms, together with SNAP25 and Syntaxin-1A, the neuronal soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex and mediates exocytosis of synaptic vesicles with the pre-synaptic membrane. While Synaptobrevin-2 is part of a four-helix bundle in this SNARE complex, it is natively unstructured in the absence of lipids or other SNARE proteins. Partially folded segments, presumably SNARE complex formation intermediates, as well as formation of Synaptobrevin-2 dimers and oligomers, were identified in previous studies. Here, we employ three Synaptobrevin-2 variants-the full-length protein Syb(1-116), the soluble, cytosolic variant Syb(1-96) as well as a shorter version Syb(49-96) containing structured segments but omitting a trigger site for SNARE complex formation-to study oligomerisation in the absence of interaction partners or when incorporated into the lipid bilayer of liposomes. Combining native mass spectrometry with chemical cross-linking, we find that the truncated versions show increased oligomerisation. Our findings from both techniques agree well and confirm the presence of oligomers in solution while membrane-bound Synaptobrevin-2 is mostly monomeric. Using ion mobility mass spectrometry, we could further show that lower charge states of Syb(49-96) oligomers, which most likely represent solution structures, follow an isotropic growth curve suggesting that they are intrinsically disordered. From a technical point of view, we show that the combination of native ion mobility mass spectrometry with chemical cross-linking is well-suited for the analysis of protein homo-oligomers. Graphical Abstract ᅟ.
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Affiliation(s)
- Sabine Wittig
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany
| | - Caroline Haupt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany
| | - Waldemar Hoffmann
- Institute of Chemistry and Biochemistry - Organic Chemistry, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradaystr. 4-6, 14195, Berlin, Germany
| | - Susann Kostmann
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany
| | - Kevin Pagel
- Institute of Chemistry and Biochemistry - Organic Chemistry, Freie Universität Berlin, Takustr. 3, 14195, Berlin, Germany
| | - Carla Schmidt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany.
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24
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Huang Y, Huang S, Di Scala C, Wang Q, Wandall HH, Fantini J, Zhang YQ. The glycosphingolipid MacCer promotes synaptic bouton formation in Drosophila by interacting with Wnt. eLife 2018; 7:38183. [PMID: 30355446 PMCID: PMC6202054 DOI: 10.7554/elife.38183] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 09/09/2018] [Indexed: 01/05/2023] Open
Abstract
Lipids are structural components of cellular membranes and signaling molecules that are widely involved in development and diseases, but the underlying molecular mechanisms are poorly understood, partly because of the vast variety of lipid species and complexity of synthetic and turnover pathways. From a genetic screen, we identify that mannosyl glucosylceramide (MacCer), a species of glycosphingolipid (GSL), promotes synaptic bouton formation at the Drosophila neuromuscular junction (NMJ). Pharmacological and genetic analysis shows that the NMJ growth-promoting effect of MacCer depends on normal lipid rafts, which are known to be composed of sphingolipids, sterols and select proteins. MacCer positively regulates the synaptic level of Wnt1/Wingless (Wg) and facilitates presynaptic Wg signaling, whose activity is raft-dependent. Furthermore, a functional GSL-binding motif in Wg exhibiting a high affinity for MacCer is required for normal NMJ growth. These findings reveal a novel mechanism whereby the GSL MacCer promotes synaptic bouton formation via Wg signaling.
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Affiliation(s)
- Yan Huang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, CAS Center for Excellence in Brain Science and Intelligence Technology, Beijing, China
| | - Sheng Huang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, CAS Center for Excellence in Brain Science and Intelligence Technology, Beijing, China.,Sino-Danish College, Sino-Danish Center for Education and Research, Chinese Academy of Sciences, Beijing, China
| | | | - Qifu Wang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, CAS Center for Excellence in Brain Science and Intelligence Technology, Beijing, China
| | - Hans H Wandall
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacques Fantini
- UNIS UMR_S 1072, INSERM, Aix-Marseille Université, Marseille, France
| | - Yong Q Zhang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, CAS Center for Excellence in Brain Science and Intelligence Technology, Beijing, China
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25
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Sharma S, Lindau M. The fusion pore, 60 years after the first cartoon. FEBS Lett 2018; 592:3542-3562. [PMID: 29904915 DOI: 10.1002/1873-3468.13160] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/07/2018] [Accepted: 06/12/2018] [Indexed: 11/10/2022]
Abstract
Neurotransmitter release occurs in the form of quantal events by fusion of secretory vesicles with the plasma membrane, and begins with the formation of a fusion pore that has a conductance similar to that of a large ion channel or gap junction. In this review, we propose mechanisms of fusion pore formation and discuss their implications for fusion pore structure and function. Accumulating evidence indicates a direct role of soluble N-ethylmaleimide-sensitive-factor attachment receptor proteins in the opening of fusion pores. Fusion pores are likely neither protein channels nor purely lipid, but are of proteolipidic composition. Future perspectives to gain better insight into the molecular structure of fusion pores are discussed.
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Affiliation(s)
- Satyan Sharma
- Laboratory for Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Manfred Lindau
- Laboratory for Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.,School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
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26
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Abstract
Phosphoinositides (PtdIns) play important roles in exocytosis and are thought to regulate secretory granule docking by co-clustering with the SNARE protein syntaxin to form a docking receptor in the plasma membrane. Here we tested this idea by high-resolution total internal reflection imaging of EGFP-labeled PtdIns markers or syntaxin-1 at secretory granule release sites in live insulin-secreting cells. In intact cells, PtdIns markers distributed evenly across the plasma membrane with no preference for granule docking sites. In contrast, syntaxin-1 was found clustered in the plasma membrane, mostly beneath docked granules. We also observed rapid accumulation of syntaxin-1 at sites where granules arrived to dock. Acute depletion of plasma membrane phosphatidylinositol (4,5) bisphosphate (PtdIns(4,5)P2 ) by recruitment of a 5'-phosphatase strongly inhibited Ca2+ -dependent exocytosis, but had no effect on docked granules or the distribution and clustering of syntaxin-1. Cell permeabilization by α-toxin or formaldehyde-fixation caused PtdIns marker to slowly cluster, in part near docked granules. In summary, our data indicate that PtdIns(4,5)P2 accelerates granule priming, but challenge a role of PtdIns in secretory granule docking or clustering of syntaxin-1 at the release site.
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Affiliation(s)
| | - Nikhil R Gandasi
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Sebastian Barg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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27
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Wen X, Van Hook MJ, Grassmeyer JJ, Wiesman AI, Rich GM, Cork KM, Thoreson WB. Endocytosis sustains release at photoreceptor ribbon synapses by restoring fusion competence. J Gen Physiol 2018; 150:591-611. [PMID: 29555658 PMCID: PMC5881445 DOI: 10.1085/jgp.201711919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/21/2018] [Indexed: 01/15/2023] Open
Abstract
Endocytosis is an essential process at sites of synaptic release. Not only are synaptic vesicles recycled by endocytosis, but the removal of proteins and lipids by endocytosis is needed to restore release site function at active zones after vesicle fusion. Synaptic exocytosis from vertebrate photoreceptors involves synaptic ribbons that serve to cluster vesicles near the presynaptic membrane. In this study, we hypothesize that this clustering increases the likelihood that exocytosis at one ribbon release site may disrupt release at an adjacent site and therefore that endocytosis may be particularly important for restoring release site competence at photoreceptor ribbon synapses. To test this, we combined optical and electrophysiological techniques in salamander rods. Pharmacological inhibition of dynamin-dependent endocytosis rapidly inhibits release from synaptic ribbons and slows recovery of ribbon-mediated release from paired pulse synaptic depression. Inhibiting endocytosis impairs the ability of second-order horizontal cells to follow rod light responses at frequencies as low as 2 Hz. Inhibition of endocytosis also increases lateral membrane mobility of individual Ca2+ channels, showing that it changes release site structure. Visualization of single synaptic vesicles by total internal reflection fluorescence microscopy reveals that inhibition of endocytosis reduces the likelihood of fusion among vesicles docked near ribbons and increases the likelihood that they will retreat from the membrane without fusion. Vesicle advance toward the membrane is also reduced, but the number of membrane-associated vesicles is not. Endocytosis therefore appears to be more important for restoring later steps in vesicle fusion than for restoring docking. Unlike conventional synapses in which endocytic restoration of release sites is evident only at high frequencies, endocytosis is needed to maintain release from rod ribbon synapses even at modest frequencies.
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Affiliation(s)
- Xiangyi Wen
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Matthew J Van Hook
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
| | - Justin J Grassmeyer
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Alex I Wiesman
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Grace M Rich
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
| | - Karlene M Cork
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
| | - Wallace B Thoreson
- Department of Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE
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28
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Maritzen T, Haucke V. Coupling of exocytosis and endocytosis at the presynaptic active zone. Neurosci Res 2018; 127:45-52. [DOI: 10.1016/j.neures.2017.09.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/13/2017] [Accepted: 08/25/2017] [Indexed: 01/08/2023]
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29
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Syntaxins on granules promote docking of granules via interactions with munc18. Sci Rep 2018; 8:193. [PMID: 29317735 PMCID: PMC5760731 DOI: 10.1038/s41598-017-18597-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 12/13/2017] [Indexed: 01/02/2023] Open
Abstract
SNAREs and SNARE-binding accessory proteins are believed to be central molecular components of neurotransmitter release, although the precise sequence of molecular events corresponding to distinct physiological states is unclear. The mechanism of docking of vesicles to the plasma membrane remains elusive, as the anchoring protein residing on vesicles is unknown. Here I show that targeting small amounts of syntaxin to granules by transmembrane domain alteration leads to a substantial enhancement of syntaxin clustering beneath granules, as well as of morphological granule docking. The effect was abolished without munc18 and strongly reduced by removal of the N-terminal peptide in the syntaxin mutant. Thus, in contrast to the current paradigm, I demonstrate that syntaxin acts from the vesicular membrane, strongly facilitating docking of vesicles, likely via interaction of its N-peptide with munc18. Docking was assayed by quantifying the syntaxin clusters beneath granules, using two-color Total Internal Reflectance Fluorescence microscopy in live PC-12 cells and confirmed by electron microscopy. Hereby, I propose a new model of vesicle docking, wherein munc18 bridges the few syntaxin molecules residing on granules to the syntaxin cluster on the plasma membrane, suggesting that the number of syntaxins on vesicles determines docking and conceivably fusion probability.
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30
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The Dual Function of the Polybasic Juxtamembrane Region of Syntaxin 1A in Clamping Spontaneous Release and Stimulating Ca 2+-Triggered Release in Neuroendocrine Cells. J Neurosci 2017; 38:220-231. [PMID: 29133430 DOI: 10.1523/jneurosci.1541-17.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 09/07/2017] [Accepted: 10/07/2017] [Indexed: 11/21/2022] Open
Abstract
The exact function of the polybasic juxtamembrane region (5RK) of the plasma membrane neuronal SNARE, syntaxin 1A (Syx), in vesicle exocytosis, although widely studied, is currently not clear. Here, we addressed the role of 5RK in Ca2+-triggered release, using our Syx-based intramolecular fluorescence resonance energy transfer (FRET) probe, which previously allowed us to resolve a depolarization-induced Ca2+-dependent close-to-open transition (CDO) of Syx that occurs concomitant with evoked release, both in PC12 cells and hippocampal neurons and was abolished upon charge neutralization of 5RK. First, using dynamic FRET analysis in PC12 cells, we show that CDO occurs following assembly of SNARE complexes that include the vesicular SNARE, synaptobrevin 2, and that the participation of 5RK in CDO goes beyond its participation in the final zippering of the complex, because mutations of residues adjacent to 5RK, believed to be crucial for final zippering, do not abolish this transition. In addition, we show that CDO is contingent on membrane phosphatidylinositol 4,5-bisphosphate (PIP2), which is fundamental for maintaining regulated exocytosis, as depletion of membranal PIP2 abolishes CDO. Prompted by these results, which underscore a potentially significant role of 5RK in exocytosis, we next amperometrically analyzed catecholamine release from PC12 cells, revealing that charge neutralization of 5RK promotes spontaneous and inhibits Ca2+-triggered release events. Namely, 5RK acts as a fusion clamp, making release dependent on stimulation by Ca2+SIGNIFICANCE STATEMENT Syntaxin 1A (Syx) is a central protein component of the SNARE complex, which underlies neurotransmitter release. Although widely studied in relation to its participation in SNARE complex formation and its interaction with phosphoinositides, the function of Syx's polybasic juxtamembrane region (5RK) remains unclear. Previously, we showed that a conformational transition of Syx, related to calcium-triggered release, reported by a Syx-based FRET probe, is abolished upon charge neutralization of 5RK (5RK/A). Here we show that this conformational transition is dependent on phosphatidylinositol 4,5-bisphosphate (PIP2) and is related to SNARE complex formation. Subsequently, we show that the 5RK/A mutation enhances spontaneous release and inhibits calcium-triggered release in neuroendocrine cells, indicating a previously unrecognized role of 5RK in neurotransmitter release.
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31
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Walter AM, Müller R, Tawfik B, Wierda KD, Pinheiro PS, Nadler A, McCarthy AW, Ziomkiewicz I, Kruse M, Reither G, Rettig J, Lehmann M, Haucke V, Hille B, Schultz C, Sørensen JB. Phosphatidylinositol 4,5-bisphosphate optical uncaging potentiates exocytosis. eLife 2017; 6:30203. [PMID: 29068313 PMCID: PMC5711374 DOI: 10.7554/elife.30203] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/24/2017] [Indexed: 12/14/2022] Open
Abstract
Phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] is essential for exocytosis. Classical ways of manipulating PI(4,5)P2 levels are slower than its metabolism, making it difficult to distinguish effects of PI(4,5)P2 from those of its metabolites. We developed a membrane-permeant, photoactivatable PI(4,5)P2, which is loaded into cells in an inactive form and activated by light, allowing sub-second increases in PI(4,5)P2 levels. By combining this compound with electrophysiological measurements in mouse adrenal chromaffin cells, we show that PI(4,5)P2 uncaging potentiates exocytosis and identify synaptotagmin-1 (the Ca2+ sensor for exocytosis) and Munc13-2 (a vesicle priming protein) as the relevant effector proteins. PI(4,5)P2 activation of exocytosis did not depend on the PI(4,5)P2-binding CAPS-proteins, suggesting that PI(4,5)P2 uncaging may bypass CAPS-function. Finally, PI(4,5)P2 uncaging triggered the rapid fusion of a subset of readily-releasable vesicles, revealing a rapid role of PI(4,5)P2 in fusion triggering. Thus, optical uncaging of signaling lipids can uncover their rapid effects on cellular processes and identify lipid effectors. Cells in our body communicate by releasing compounds called transmitters that carry signals from one cell to the next. Packages called vesicles store transmitters within the signaling cell. When the cell needs to send a signal, the vesicles fuse with the cell's membrane and release their cargo. For many signaling processes, such as those used by neurons, this fusion is regulated, fast, and coupled to the signal that the cell receives to activate release. Specialized molecular machines made up of proteins and fatty acid molecules called signaling lipids enable this to happen. One signaling lipid called PI(4,5)P2 (short for phosphatidylinositol 4,5-bisphosphate) is essential for vesicle fusion as well as for other processes in cells. It interacts with several proteins that help it control fusion and the release of transmitter. While it is possible to study the role of these proteins using genetic tools to inactivate them, the signaling lipids are more difficult to manipulate. Existing methods result in slow changes in PI(4,5)P2 levels, making it hard to directly attribute later changes to PI(4,5)P2. Walter, Müller, Tawfik et al. developed a new method to measure how PI(4,5)P2 affects transmitter release in living mammalian cells, which causes a rapid increase in PI(4,5)P2 levels. The method uses a chemical compound called “caged PI(4,5)P2” that can be loaded into cells but remains undetected until ultraviolet light is shone on it. The ultraviolet light uncages the compound, generating active PI(4,5)P2 in less than one second. Walter et al. found that when they uncaged PI(4,5)P2 in this way, the amount of transmitter released by cells increased. Combining this with genetic tools, it was possible to investigate which proteins of the release machinery were required for this effect. The results suggest that two different types of proteins that interact with PI(4,5)P2 are needed: one must bind PI(4,5)P2 to carry out its role and the other helps PI(4,5)P2 accumulate at the site of vesicle fusion. The new method also allowed Walter et al. to show that a fast increase in PI(4,5)P2 triggers a subset of vesicles to fuse very rapidly. This shows that PI(4,5)P2 rapidly regulates the release of transmitter. Caged PI(4,5)P2 will be useful to study other processes in cells that need PI(4,5)P2, helping scientists understand more about how signaling lipids control many different events at cellular membranes.
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Affiliation(s)
- Alexander M Walter
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Rainer Müller
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Bassam Tawfik
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Keimpe Db Wierda
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Paulo S Pinheiro
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - André Nadler
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Anthony W McCarthy
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Iwona Ziomkiewicz
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Discovery Sciences, AstraZeneca, Cambridge, United Kingdom
| | - Martin Kruse
- Department of Physiology and Biophysics, School of Medicine, University of Washington, Seattle, United States
| | - Gregor Reither
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jens Rettig
- Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Bertil Hille
- Department of Physiology and Biophysics, School of Medicine, University of Washington, Seattle, United States
| | - Carsten Schultz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jakob Balslev Sørensen
- Neurosecretion group, Center for Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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32
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Gasman S, Vitale N. Lipid remodelling in neuroendocrine secretion. Biol Cell 2017; 109:381-390. [DOI: 10.1111/boc.201700030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; Strasbourg France
- INSERM; Paris Cedex 75654 France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives; CNRS UPR3212; Université de Strasbourg; Strasbourg France
- INSERM; Paris Cedex 75654 France
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33
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Wu Z, Thiyagarajan S, O'Shaughnessy B, Karatekin E. Regulation of Exocytotic Fusion Pores by SNARE Protein Transmembrane Domains. Front Mol Neurosci 2017; 10:315. [PMID: 29066949 PMCID: PMC5641348 DOI: 10.3389/fnmol.2017.00315] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/19/2017] [Indexed: 12/26/2022] Open
Abstract
Calcium-triggered exocytotic release of neurotransmitters and hormones from neurons and neuroendocrine cells underlies neuronal communication, motor activity and endocrine functions. The core of the neuronal exocytotic machinery is composed of soluble N-ethyl maleimide sensitive factor attachment protein receptors (SNAREs). Formation of complexes between vesicle-attached v- and plasma-membrane anchored t-SNAREs in a highly regulated fashion brings the membranes into close apposition. Small, soluble proteins called Complexins (Cpx) and calcium-sensing Synaptotagmins cooperate to block fusion at low resting calcium concentrations, but trigger release upon calcium increase. A growing body of evidence suggests that the transmembrane domains (TMDs) of SNARE proteins play important roles in regulating the processes of fusion and release, but the mechanisms involved are only starting to be uncovered. Here we review recent evidence that SNARE TMDs exert influence by regulating the dynamics of the fusion pore, the initial aqueous connection between the vesicular lumen and the extracellular space. Even after the fusion pore is established, hormone release by neuroendocrine cells is tightly controlled, and the same may be true of neurotransmitter release by neurons. The dynamics of the fusion pore can regulate the kinetics of cargo release and the net amount released, and can determine the mode of vesicle recycling. Manipulations of SNARE TMDs were found to affect fusion pore properties profoundly, both during exocytosis and in biochemical reconstitutions. To explain these effects, TMD flexibility, and interactions among TMDs or between TMDs and lipids have been invoked. Exocytosis has provided the best setting in which to unravel the underlying mechanisms, being unique among membrane fusion reactions in that single fusion pores can be probed using high-resolution methods. An important role will likely be played by methods that can probe single fusion pores in a biochemically defined setting which have recently become available. Finally, computer simulations are valuable mechanistic tools because they have the power to access small length scales and very short times that are experimentally inaccessible.
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Affiliation(s)
- Zhenyong Wu
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, CT, United States.,Nanobiology Institute, Yale University, West Haven, CT, United States
| | | | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY, United States
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, CT, United States.,Nanobiology Institute, Yale University, West Haven, CT, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States.,Laboratoire de Neurophotonique, Université Paris Descartes, Faculté des Sciences Fondamentales et Biomédicales, Centre National de la Recherche Scientifique (CNRS), Paris, France
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34
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Prinslow EA, Brautigam CA, Rizo J. Reconciling isothermal titration calorimetry analyses of interactions between complexin and truncated SNARE complexes. eLife 2017; 6. [PMID: 28880148 PMCID: PMC5589412 DOI: 10.7554/elife.30286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 08/16/2017] [Indexed: 01/01/2023] Open
Abstract
Neurotransmitter release depends on the SNARE complex formed by syntaxin-1, synaptobrevin and SNAP-25, as well as on complexins, which bind to the SNARE complex and play active and inhibitory roles. A crystal structure of a Complexin-I fragment bearing a so-called 'superclamp' mutation bound to a truncated SNARE complex lacking the C-terminus of the synaptobrevin SNARE motif (SNAREΔ60) suggested that an 'accessory' α-helix of Complexin-I inhibits release by inserting into the C-terminus of the SNARE complex. Previously, isothermal titration calorimetry (ITC) experiments performed in different laboratories yielded apparently discrepant results in support or against the existence of such binding mode in solution (Trimbuch et al., 2014; Krishnakumar et al., 2015). Here, ITC experiments performed to solve these discrepancies now show that the region containing the Complexin-I accessory helix and preceding N-terminal sequences does interact with SNAREΔ60, but the interaction requires the polybasic juxtamembrane region of syntaxin-1 and is not affected by the superclamp mutation within the experimental error of these experiments.
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Affiliation(s)
- Eric A Prinslow
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Chad A Brautigam
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
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35
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Sipe CW, Siegrist SE. Eyeless uncouples mushroom body neuroblast proliferation from dietary amino acids in Drosophila. eLife 2017; 6:26343. [PMID: 28826476 PMCID: PMC5576483 DOI: 10.7554/elife.26343] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 08/08/2017] [Indexed: 11/13/2022] Open
Abstract
Cell proliferation is coupled with nutrient availability. If nutrients become limited, proliferation ceases, because growth factor and/or PI3-kinase activity levels become attenuated. Here, we report an exception to this generality within a subpopulation of Drosophila neural stem cells (neuroblasts). We find that most neuroblasts enter and exit cell cycle in a nutrient-dependent manner that is reversible and regulated by PI3-kinase. However, a small subset, the mushroom body neuroblasts, which generate neurons important for memory and learning, divide independent of dietary nutrient conditions and PI3-kinase activity. This nutrient-independent proliferation is regulated by Eyeless, a Pax-6 orthologue, expressed in mushroom body neuroblasts. When Eyeless is knocked down, mushroom body neuroblasts exit cell cycle when nutrients are withdrawn. Conversely, when Eyeless is ectopically expressed, some non-mushroom body neuroblasts divide independent of dietary nutrient conditions. Therefore, Eyeless uncouples MB neuroblast proliferation from nutrient availability, allowing preferential neurogenesis in brain subregions during nutrient poor conditions.
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Affiliation(s)
- Conor W Sipe
- Department of Biology, University of Virginia, Charlottesville, United States
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, Charlottesville, United States
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36
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Chardonnet S, Bessiron T, Ramos CI, Dammak R, Richard MA, Boursier C, Cadilhac C, Coquelle FM, Bossi S, Ango F, Le Maréchal P, Decottignies P, Berrier C, McLean H, Daniel H. Native metabotropic glutamate receptor 4 depresses synaptic transmission through an unusual Gα q transduction pathway. Neuropharmacology 2017; 121:247-260. [PMID: 28456688 DOI: 10.1016/j.neuropharm.2017.04.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 04/22/2017] [Accepted: 04/24/2017] [Indexed: 01/13/2023]
Abstract
In cerebellar cortex, mGlu4 receptors located on parallel fibers play an essential role in normal motor function, but the molecular mechanisms involved are not yet completely understood. Using a strategy combining biochemical and electrophysiological approaches in the rodent cerebellum, we demonstrate that presynaptic mGlu4 receptors control synaptic transmission through an atypical activation of Gαq proteins. First, the Gαq subunit, PLC and PKC signaling proteins present in cerebellar extracts are retained on affinity chromatography columns grafted with different sequences of the cytoplasmic domain of mGlu4 receptor. The i2 loop and the C terminal domain were used as baits, two domains that are known to play a pivotal role in coupling selectivity and efficacy. Second, in situ proximity ligation assays show that native mGlu4 receptors and Gαq subunits are in close physical proximity in cerebellar cortical slices. Finally, electrophysiological experiments demonstrate that the molecular mechanisms underlying mGlu4 receptor-mediated inhibition of transmitter release at cerebellar Parallel Fiber (PF) - Molecular Layer Interneuron (MLI) synapses involves the Gαq-PLC signaling pathway. Taken together, our results provide compelling evidence that, in the rodent cerebellar cortex, mGlu4 receptors act by coupling to the Gαq protein and PLC effector system to reduce glutamate synaptic transmission.
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Affiliation(s)
- Solenne Chardonnet
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Thomas Bessiron
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Cathy Isaura Ramos
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Raoudha Dammak
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Marie-Ange Richard
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Céline Boursier
- Plateforme de Transcriptomique et Protéomique (Trans-Prot), UMS-IPSIT, Univ Paris Sud CNRS Inserm, F- 92296 Chatenay-Malabry, France
| | - Christelle Cadilhac
- Equipe Mise en place des circuits GABAergiques, Institut de Génomique Fonctionnelle, CNRS UMR 5203, F-34094 Montpellier Cedex 5, France
| | - Frédéric M Coquelle
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette Cedex, France
| | - Simon Bossi
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Fabrice Ango
- Equipe Mise en place des circuits GABAergiques, Institut de Génomique Fonctionnelle, CNRS UMR 5203, F-34094 Montpellier Cedex 5, France
| | - Pierre Le Maréchal
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Paulette Decottignies
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Catherine Berrier
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Heather McLean
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France
| | - Hervé Daniel
- Equipe Pharmacologie et Biochimie de la Synapse, NeuroPSI - UMR 9197 « Univ Paris-sud - CNRS », Université Paris-Sud, F-91405 Orsay, France.
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37
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Lin A, Hu Q, Li C, Xing Z, Ma G, Wang C, Li J, Ye Y, Yao J, Liang K, Wang S, Park PK, Marks JR, Zhou Y, Zhou J, Hung MC, Liang H, Hu Z, Shen H, Hawke DH, Han L, Zhou Y, Lin C, Yang L. The LINK-A lncRNA interacts with PtdIns(3,4,5)P 3 to hyperactivate AKT and confer resistance to AKT inhibitors. Nat Cell Biol 2017; 19:238-251. [PMID: 28218907 PMCID: PMC5332298 DOI: 10.1038/ncb3473] [Citation(s) in RCA: 202] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/12/2017] [Indexed: 12/13/2022]
Abstract
Phosphatidylinositol-3,4,5-trisphosphate (PIP3) mediates signaling pathways as a second messenger in response to extracellular signals. Although primordial functions of phospholipids and RNAs have been hypothesized in the “RNA world”, physiological RNA-phospholipid interactions and their involvement in essential cellular processes has remained a mystery. We explicate the contribution of lipid-binding long non-coding RNAs (lncRNAs) in cancer cells. Among them, Long Intergenic Noncoding RNA for Kinase Activation (LINK-A) directly interacts with AKT pleckstrin homology domain and PIP3 at the single nucleotide level, facilitating AKT-PIP3 interaction and consequent enzymatic activation. LINK-A-dependent AKT hyperactivation leads to tumorigenesis and resistance to AKT inhibitors. Genomic deletions of the LINK-A PIP3-binding motif dramatically sensitized breast cancer cells to AKT inhibitors. Furthermore, meta-analysis showed the correlation between LINK-A expression and incidence of a SNP (rs12095274: A>G), AKT phosphorylation status, and poor outcomes for breast and lung cancer patients. PIP3-binding lncRNA modulates AKT activation with broad clinical implications.
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Affiliation(s)
- Aifu Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Qingsong Hu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Chunlai Li
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Zhen Xing
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Guolin Ma
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Cheng Wang
- Department of Epidemiology and Biostatistics and Ministry of Education (MOE) Key Lab for Modern Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Jun Li
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of System Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yin Ye
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Jun Yao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Ke Liang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Shouyu Wang
- Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Peter K Park
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Jeffrey R Marks
- Department of Surgery, Division of Surgical Science, Duke University, School of Medicine, Durham, North Carolina 27710, USA
| | - Yan Zhou
- Department of Oncology, Yixing People's Hospital, Yixing 214200, China
| | - Jianwei Zhou
- Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Graduate Institute of Cancer Biology and Center for Molecular Medicine, China Medical University, Taichung 404, Taiwan
| | - Han Liang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of System Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Zhibin Hu
- Department of Epidemiology and Biostatistics and Ministry of Education (MOE) Key Lab for Modern Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Hongbing Shen
- Department of Epidemiology and Biostatistics and Ministry of Education (MOE) Key Lab for Modern Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - David H Hawke
- Department of System Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Leng Han
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, Texas 77030, USA
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA
| | - Chunru Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Liuqing Yang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
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38
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Doyle SE, Pahl MC, Siller KH, Ardiff L, Siegrist SE. Neuroblast niche position is controlled by Phosphoinositide 3-kinase-dependent DE-Cadherin adhesion. Development 2017; 144:820-829. [PMID: 28126840 DOI: 10.1242/dev.136713] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 01/09/2017] [Indexed: 01/01/2023]
Abstract
Correct positioning of stem cells within their niche is essential for tissue morphogenesis and homeostasis. How stem cells acquire and maintain niche position remains largely unknown. Here, we show that a subset of brain neuroblasts (NBs) in Drosophila utilize Phosphoinositide 3-kinase (PI3-kinase) and DE-cadherin to build adhesive contact for NB niche positioning. NBs remain within their native microenvironment when levels of PI3-kinase activity and DE-cadherin are elevated in NBs. This occurs through PI3-kinase-dependent regulation of DE-Cadherin-mediated cell adhesion between NBs and neighboring cortex glia, and between NBs and their ganglion mother cell daughters. When levels of PI3-kinase activity and/or DE-Cadherin are reduced in NBs, NBs lose niche position and relocate to a non-native brain region that is rich in neurosecretory neurons, including those that secrete some of the Drosophila insulin-like peptides. Linking levels of PI3-kinase activity to the strength of adhesive attachment could provide cancer stem cells and hematopoietic stem cells with a means to cycle from trophic-poor to trophic-rich microenvironments.
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Affiliation(s)
- Susan E Doyle
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Matthew C Pahl
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Karsten H Siller
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Lindsay Ardiff
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
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39
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Dun AR, Lord GJ, Wilson RS, Kavanagh DM, Cialowicz KI, Sugita S, Park S, Yang L, Smyth AM, Papadopulos A, Rickman C, Duncan RR. Navigation through the Plasma Membrane Molecular Landscape Shapes Random Organelle Movement. Curr Biol 2017; 27:408-414. [PMID: 28089515 PMCID: PMC5300901 DOI: 10.1016/j.cub.2016.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/05/2016] [Accepted: 12/02/2016] [Indexed: 12/13/2022]
Abstract
Eukaryotic plasma membrane organization theory has long been controversial, in part due to a dearth of suitably high-resolution techniques to probe molecular architecture in situ and integrate information from diverse data streams [1]. Notably, clustered patterning of membrane proteins is a commonly conserved feature across diverse protein families (reviewed in [2]), including the SNAREs [3], SM proteins [4, 5], ion channels [6, 7], and receptors (e.g., [8]). Much effort has gone into analyzing the behavior of secretory organelles [9-13], and understanding the relationship between the membrane and proximal organelles [4, 5, 12, 14] is an essential goal for cell biology as broad concepts or rules may be established. Here we explore the generally accepted model that vesicles at the plasmalemma are guided by cytoskeletal tracks to specific sites on the membrane that have clustered molecular machinery for secretion [15], organized in part by the local lipid composition [16]. To increase our understanding of these fundamental processes, we integrated nanoscopy and spectroscopy of the secretory machinery with organelle tracking data in a mathematical model, iterating with knockdown cell models. We find that repeated routes followed by successive vesicles, the re-use of similar fusion sites, and the apparently distinct vesicle "pools" are all fashioned by the Brownian behavior of organelles overlaid on navigation between non-reactive secretory protein molecular depots patterned at the plasma membrane.
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Affiliation(s)
- Alison R Dun
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Gabriel J Lord
- Department of Mathematics, Maxwell Institute, MACS, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Rhodri S Wilson
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Deirdre M Kavanagh
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Katarzyna I Cialowicz
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Shuzo Sugita
- Toronto Western Research Institute, Room 11-432, McLaughlin Wing, 399 Bathurst St., Toronto, ON M5T 2S8, Canada
| | - Seungmee Park
- Toronto Western Research Institute, Room 11-432, McLaughlin Wing, 399 Bathurst St., Toronto, ON M5T 2S8, Canada
| | - Lei Yang
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Annya M Smyth
- Centre for Inflammation Research, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Andreas Papadopulos
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Colin Rickman
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium
| | - Rory R Duncan
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, UK; Edinburgh Super-Resolution Imaging Consortium.
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40
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Bademosi AT, Lauwers E, Padmanabhan P, Odierna L, Chai YJ, Papadopulos A, Goodhill GJ, Verstreken P, van Swinderen B, Meunier FA. In vivo single-molecule imaging of syntaxin1A reveals polyphosphoinositide- and activity-dependent trapping in presynaptic nanoclusters. Nat Commun 2017; 8:13660. [PMID: 28045048 PMCID: PMC5171881 DOI: 10.1038/ncomms13660] [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: 10/21/2016] [Indexed: 01/03/2023] Open
Abstract
Syntaxin1A is organized in nanoclusters that are critical for the docking and priming of secretory vesicles from neurosecretory cells. Whether and how these nanoclusters are affected by neurotransmitter release in nerve terminals from a living organism is unknown. Here we imaged photoconvertible syntaxin1A-mEos2 in the motor nerve terminal of Drosophila larvae by single-particle tracking photoactivation localization microscopy. Opto- and thermo-genetic neuronal stimulation increased syntaxin1A-mEos2 mobility, and reduced the size and molecular density of nanoclusters, suggesting an activity-dependent release of syntaxin1A from the confinement of nanoclusters. Syntaxin1A mobility was increased by mutating its polyphosphoinositide-binding site or preventing SNARE complex assembly via co-expression of tetanus toxin light chain. In contrast, syntaxin1A mobility was reduced by preventing SNARE complex disassembly. Our data demonstrate that polyphosphoinositide favours syntaxin1A trapping, and show that SNARE complex disassembly leads to syntaxin1A dissociation from nanoclusters. Lateral diffusion and trapping of syntaxin1A in nanoclusters therefore dynamically regulate neurotransmitter release. Syntaxin1A (Sx1A) is organized in nanoclusters in neurosecretory cells but how these nanoclusters are affected by neurotransmitter release in a living organism is unknown. Here the authors perform single molecule imaging analysis in live fly larvae and show that the lateral diffusion and trapping of Sx1A in nanoclusters are altered by synaptic activity.
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Affiliation(s)
- Adekunle T Bademosi
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Elsa Lauwers
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium.,KU Leuven Department of Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), 3000 Leuven, Belgium
| | - Pranesh Padmanabhan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Lorenzo Odierna
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ye Jin Chai
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geoffrey J Goodhill
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.,School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Patrik Verstreken
- VIB Center for the Biology of Disease, 3000 Leuven, Belgium.,KU Leuven Department of Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), 3000 Leuven, Belgium
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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41
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Bocharov EV, Mineev KS, Pavlov KV, Akimov SA, Kuznetsov AS, Efremov RG, Arseniev AS. Helix-helix interactions in membrane domains of bitopic proteins: Specificity and role of lipid environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:561-576. [PMID: 27884807 DOI: 10.1016/j.bbamem.2016.10.024] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/18/2016] [Accepted: 10/20/2016] [Indexed: 12/23/2022]
Abstract
Interaction between transmembrane helices often determines biological activity of membrane proteins. Bitopic proteins, a broad subclass of membrane proteins, form dimers containing two membrane-spanning helices. Some aspects of their structure-function relationship cannot be fully understood without considering the protein-lipid interaction, which can determine the protein conformational ensemble. Experimental and computer modeling data concerning transmembrane parts of bitopic proteins are reviewed in the present paper. They highlight the importance of lipid-protein interactions and resolve certain paradoxes in the behavior of such proteins. Besides, some properties of membrane organization provided a clue to understanding of allosteric interactions between distant parts of proteins. Interactions of these kinds appear to underlie a signaling mechanism, which could be widely employed in the functioning of many membrane proteins. Treatment of membrane proteins as parts of integrated fine-tuned proteolipid system promises new insights into biological function mechanisms and approaches to drug design. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Eduard V Bocharov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation; National Research Centre "Kurchatov Institute", Akad. Kurchatova pl. 1, Moscow, 123182, Russian Federation.
| | - Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation
| | - Konstantin V Pavlov
- Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Leninskiy prospect 31/5, Moscow, 119071, Russian Federation
| | - Sergey A Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Leninskiy prospect 31/5, Moscow, 119071, Russian Federation; National University of Science and Technology "MISiS", Leninskiy prospect 4, Moscow, 119049, Russian Federation
| | - Andrey S Kuznetsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation; Higher School of Economics, Myasnitskaya ul. 20, Moscow, 101000, Russian Federation
| | - Alexander S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation.
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42
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Kam TI, Park H, Gwon Y, Song S, Kim SH, Moon SW, Jo DG, Jung YK. FcγRIIb-SHIP2 axis links Aβ to tau pathology by disrupting phosphoinositide metabolism in Alzheimer's disease model. eLife 2016; 5. [PMID: 27834631 PMCID: PMC5106215 DOI: 10.7554/elife.18691] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 10/17/2016] [Indexed: 02/02/2023] Open
Abstract
Amyloid-β (Aβ)-containing extracellular plaques and hyperphosphorylated tau-loaded intracellular neurofibrillary tangles are neuropathological hallmarks of Alzheimer's disease (AD). Although Aβ exerts neuropathogenic activity through tau, the mechanistic link between Aβ and tau pathology remains unknown. Here, we showed that the FcγRIIb-SHIP2 axis is critical in Aβ1-42-induced tau pathology. Fcgr2b knockout or antagonistic FcγRIIb antibody inhibited Aβ1-42-induced tau hyperphosphorylation and rescued memory impairments in AD mouse models. FcγRIIb phosphorylation at Tyr273 was found in AD brains, in neuronal cells exposed to Aβ1-42, and recruited SHIP2 to form a protein complex. Consequently, treatment with Aβ1-42 increased PtdIns(3,4)P2 levels from PtdIns(3,4,5)P3 to mediate tau hyperphosphorylation. Further, we found that targeting SHIP2 expression by lentiviral siRNA in 3xTg-AD mice or pharmacological inhibition of SHIP2 potently rescued tau hyperphosphorylation and memory impairments. Thus, we concluded that the FcγRIIb-SHIP2 axis links Aβ neurotoxicity to tau pathology by dysregulating PtdIns(3,4)P2 metabolism, providing insight into therapeutic potential against AD.
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Affiliation(s)
- Tae-In Kam
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea.,Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Baltimore, United States.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Hyejin Park
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea.,Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Baltimore, United States.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Youngdae Gwon
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Sungmin Song
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Seo-Hyun Kim
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Seo Won Moon
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea
| | - Dong-Gyu Jo
- School of Pharmacy, Sungkyunkwan University, Suwon, Korea
| | - Yong-Keun Jung
- Global Research Laboratory, School of Biological Sciences, Seoul National University, Seoul, Korea
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43
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Beer KB, Wehman AM. Mechanisms and functions of extracellular vesicle release in vivo-What we can learn from flies and worms. Cell Adh Migr 2016; 11:135-150. [PMID: 27689411 PMCID: PMC5351733 DOI: 10.1080/19336918.2016.1236899] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cells from bacteria to man release extracellular vesicles (EVs) that contain signaling molecules like proteins, lipids, and nucleic acids. The content, formation, and signaling roles of these conserved vesicles are diverse, but the physiological relevance of EV signaling in vivo is still debated. Studies in classical genetic model organisms like C. elegans and Drosophila have begun to reveal the developmental and behavioral roles for EVs. In this review, we discuss the emerging evidence for the in vivo signaling roles of EVs. Significant effort has also been made to understand the mechanisms behind the formation and release of EVs, specifically of exosomes derived from exocytosis of multivesicular bodies and of microvesicles derived from plasma membrane budding called ectocytosis. In this review, we detail the impact of flies and worms on understanding the proteins and lipids involved in EV biogenesis and highlight the open questions in the field.
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Affiliation(s)
- Katharina B Beer
- a Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg , Würzburg , Germany
| | - Ann Marie Wehman
- a Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg , Würzburg , Germany
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44
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Fischer B, Lüthy K, Paesmans J, De Koninck C, Maes I, Swerts J, Kuenen S, Uytterhoeven V, Verstreken P, Versées W. Skywalker-TBC1D24 has a lipid-binding pocket mutated in epilepsy and required for synaptic function. Nat Struct Mol Biol 2016; 23:965-973. [DOI: 10.1038/nsmb.3297] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 08/25/2016] [Indexed: 01/08/2023]
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45
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Membrane Lipids in Presynaptic Function and Disease. Neuron 2016; 90:11-25. [DOI: 10.1016/j.neuron.2016.02.033] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/28/2016] [Accepted: 02/18/2016] [Indexed: 12/20/2022]
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46
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Uytterhoeven V, Lauwers E, Maes I, Miskiewicz K, Melo MN, Swerts J, Kuenen S, Wittocx R, Corthout N, Marrink SJ, Munck S, Verstreken P. Hsc70-4 Deforms Membranes to Promote Synaptic Protein Turnover by Endosomal Microautophagy. Neuron 2016; 88:735-48. [PMID: 26590345 DOI: 10.1016/j.neuron.2015.10.012] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/10/2015] [Accepted: 09/28/2015] [Indexed: 11/26/2022]
Abstract
Synapses are often far from their cell bodies and must largely independently cope with dysfunctional proteins resulting from synaptic activity and stress. To identify membrane-associated machines that can engulf synaptic targets destined for degradation, we performed a large-scale in vitro liposome-based screen followed by functional studies. We identified a presynaptically enriched chaperone Hsc70-4 that bends membranes based on its ability to oligomerize. This activity promotes endosomal microautophagy and the turnover of specific synaptic proteins. Loss of microautophagy slows down neurotransmission while gain of microautophagy increases neurotransmission. Interestingly, Sgt, a cochaperone of Hsc70-4, is able to switch the activity of Hsc70-4 from synaptic endosomal microautophagy toward chaperone activity. Hence, Hsc70-4 controls rejuvenation of the synaptic protein pool in a dual way: either by refolding proteins together with Sgt, or by targeting them for degradation by facilitating endosomal microautophagy based on its membrane deforming activity.
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Affiliation(s)
- Valerie Uytterhoeven
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Elsa Lauwers
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium.
| | - Ine Maes
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Katarzyna Miskiewicz
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Manuel N Melo
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jef Swerts
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Sabine Kuenen
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Rafaël Wittocx
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Nikky Corthout
- VIB Bio-Imaging Core Facility, Herestraat 49, 3000 Leuven, Belgium
| | - Siewert-Jan Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Sebastian Munck
- VIB Bio-Imaging Core Facility, Herestraat 49, 3000 Leuven, Belgium
| | - Patrik Verstreken
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium.
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Milovanovic D, Platen M, Junius M, Diederichsen U, Schaap IAT, Honigmann A, Jahn R, van den Bogaart G. Calcium Promotes the Formation of Syntaxin 1 Mesoscale Domains through Phosphatidylinositol 4,5-Bisphosphate. J Biol Chem 2016; 291:7868-76. [PMID: 26884341 PMCID: PMC4824995 DOI: 10.1074/jbc.m116.716225] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a minor component of total plasma membrane lipids, but it has a substantial role in the regulation of many cellular functions, including exo- and endocytosis. Recently, it was shown that PI(4,5)P2and syntaxin 1, a SNARE protein that catalyzes regulated exocytosis, form domains in the plasma membrane that constitute recognition sites for vesicle docking. Also, calcium was shown to promote syntaxin 1 clustering in the plasma membrane, but the molecular mechanism was unknown. Here, using a combination of superresolution stimulated emission depletion microscopy, FRET, and atomic force microscopy, we show that Ca(2+)acts as a charge bridge that specifically and reversibly connects multiple syntaxin 1/PI(4,5)P2complexes into larger mesoscale domains. This transient reorganization of the plasma membrane by physiological Ca(2+)concentrations is likely to be important for Ca(2+)-regulated secretion.
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Affiliation(s)
- Dragomir Milovanovic
- From the Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, the Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06511
| | - Mitja Platen
- the Third Institute of Physics, Faculty of Physics
| | - Meike Junius
- Institute for Organic and Biomolecular Chemistry, Georg August University, 37077 Göttingen, Germany
| | - Ulf Diederichsen
- Institute for Organic and Biomolecular Chemistry, Georg August University, 37077 Göttingen, Germany
| | - Iwan A T Schaap
- the Third Institute of Physics, Faculty of Physics, the School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Alf Honigmann
- the Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany, and
| | - Reinhard Jahn
- From the Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany,
| | - Geert van den Bogaart
- From the Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany, the Department of Tumor Immunology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
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48
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Analyzing Protein Clusters on the Plasma Membrane: Application of Spatial Statistical Analysis Methods on Super-Resolution Microscopy Images. FOCUS ON BIO-IMAGE INFORMATICS 2016; 219:95-122. [DOI: 10.1007/978-3-319-28549-8_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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49
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Destainville N, Schmidt TH, Lang T. Where Biology Meets Physics--A Converging View on Membrane Microdomain Dynamics. CURRENT TOPICS IN MEMBRANES 2015; 77:27-65. [PMID: 26781829 DOI: 10.1016/bs.ctm.2015.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
For several decades, the phenomenon of membrane component segregation into microdomains has been a well-known and highly debated subject, and varying concepts including the raft hypothesis, the fence-and-picket model, hydrophobic-mismatch, and specific protein-protein interactions have been offered as explanations. Here, we review the level of insight into the molecular architecture of membrane domains one is capable of obtaining through biological experimentation. Using SNARE proteins as a paradigm, comprehensive data suggest that several dozens of molecules crowd together into almost circular spots smaller than 100 nm. Such clusters are highly dynamical as they constantly capture and lose molecules. The organization has a strong influence on the functional availability of proteins and likely provides a molecular scaffold for more complex protein networks. Despite this high level of insight, fundamental open questions remain, applying not only to SNARE protein domains but more generally to all types of membrane domains. In this context, we explain the view of physical models and how they are beneficial in advancing our concept of micropatterning. While biological models generally remain qualitative and descriptive, physics aims towards making them quantitative and providing reproducible numbers, in order to discriminate between different mechanisms which have been proposed to account for experimental observations. Despite the fundamental differences in biological and physical approaches as far as cell membrane microdomains are concerned, we are able to show that convergence on common points of views is in reach.
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Affiliation(s)
- Nicolas Destainville
- Laboratoire de Physique Theorique (IRSAMC), Universite Toulouse 3-Paul Sabatier, UPS/CNRS, Toulouse, France
| | - Thomas H Schmidt
- Department of Membrane Biochemistry, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Thorsten Lang
- Department of Membrane Biochemistry, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
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Ji C, Zhang Y, Xu P, Xu T, Lou X. Nanoscale Landscape of Phosphoinositides Revealed by Specific Pleckstrin Homology (PH) Domains Using Single-molecule Superresolution Imaging in the Plasma Membrane. J Biol Chem 2015; 290:26978-26993. [PMID: 26396197 DOI: 10.1074/jbc.m115.663013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P2-enriched membrane patches/domains of diverse sizes (383 ± 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) showed similar spatial distributions as PI(4,5)P2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
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Affiliation(s)
- Chen Ji
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and
| | - Yongdeng Zhang
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuelin Lou
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and.
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