1
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Mintz Hemed N, Leal-Ortiz S, Zhao ET, Melosh NA. On-Demand, Reversible, Ultrasensitive Polymer Membrane Based on Molecular Imprinting Polymer. ACS Nano 2023; 17:5632-5643. [PMID: 36913954 PMCID: PMC10062346 DOI: 10.1021/acsnano.2c11618] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
The development of in vivo, longitudinal, real-time monitoring devices is an essential step toward continuous, precision health monitoring. Molecularly imprinted polymers (MIPs) are popular sensor capture agents that are more robust than antibodies and have been used for sensors, drug delivery, affinity separations, assays, and solid-phase extraction. However, MIP sensors are typically limited to one-time use due to their high binding affinity (>107 M-1) and slow-release kinetics (<10-4 μM/sec). To overcome this challenge, current research has focused on stimuli-responsive MIPs (SR-MIPs), which undergo a conformational change induced by external stimuli to reverse molecular binding, requiring additional chemicals or outside stimuli. Here, we demonstrate fully reversible MIP sensors based on electrostatic repulsion. Once the target analyte is bound within a thin film MIP on an electrode, a small electrical potential successfully releases the bound molecules, enabling repeated, accurate measurements. We demonstrate an electrostatically refreshed dopamine sensor with a 760 pM limit of detection, linear response profile, and accuracy even after 30 sensing-release cycles. These sensors could repeatedly detect <1 nM dopamine released from PC-12 cells in vitro, demonstrating they can longitudinally measure low concentrations in complex biological environments without clogging. Our work provides a simple and effective strategy for enhancing the use of MIPs-based biosensors for all charged molecules in continuous, real-time health monitoring and other sensing applications.
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Affiliation(s)
- Nofar Mintz Hemed
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - Sergio Leal-Ortiz
- Department
of Psychiatry and Behavioral Sciences, Stanford
University, Stanford, California 94304, United States
| | - Eric T. Zhao
- Department
of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Nicholas A. Melosh
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
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2
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Hall RN, Weill U, Drees L, Leal-Ortiz S, Li H, Khariton M, Chai C, Xue Y, Rosental B, Quake SR, Sánchez Alvarado A, Melosh NA, Fire AZ, Rink JC, Wang B. Heterologous reporter expression in the planarian Schmidtea mediterranea through somatic mRNA transfection. Cell Rep Methods 2022; 2:100298. [PMID: 36313809 PMCID: PMC9606109 DOI: 10.1016/j.crmeth.2022.100298] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 06/11/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
Planarians have long been studied for their regenerative abilities. Moving forward, tools for ectopic expression of non-native proteins will be of substantial value. Using a luminescent reporter to overcome the strong autofluorescence of planarian tissues, we demonstrate heterologous protein expression in planarian cells and live animals. Our approach is based on the introduction of mRNA through several nanotechnological and chemical transfection methods. We improve reporter expression by altering untranslated region (UTR) sequences and codon bias, facilitating the measurement of expression kinetics in both isolated cells and whole planarians using luminescence imaging. We also examine protein expression as a function of variations in the UTRs of delivered mRNA, demonstrating a framework to investigate gene regulation at the post-transcriptional level. Together, these advances expand the toolbox for the mechanistic analysis of planarian biology and establish a foundation for the development and expansion of transgenic techniques in this unique model system.
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Affiliation(s)
| | - Uri Weill
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany
| | - Leonard Drees
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany
| | - Sergio Leal-Ortiz
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Hongquan Li
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Margarita Khariton
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Chew Chai
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Yuan Xue
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Benyamin Rosental
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Faculty of Health Sciences, Center for Regenerative Medicine and Stem Cells, Ben Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Stephen R. Quake
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Howard Hughes Medical Institute, Kansas City, MO 64110, USA
| | - Nicholas A. Melosh
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA
| | - Andrew Z. Fire
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jochen C. Rink
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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3
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Ha HTT, Leal-Ortiz S, Lalwani K, Kiyonaka S, Hamachi I, Mysore SP, Montgomery JM, Garner CC, Huguenard JR, Kim SA. Shank and Zinc Mediate an AMPA Receptor Subunit Switch in Developing Neurons. Front Mol Neurosci 2018; 11:405. [PMID: 30524232 PMCID: PMC6256285 DOI: 10.3389/fnmol.2018.00405] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/15/2018] [Indexed: 11/18/2022] Open
Abstract
During development, pyramidal neurons undergo dynamic regulation of AMPA receptor (AMPAR) subunit composition and density to help drive synaptic plasticity and maturation. These normal developmental changes in AMPARs are particularly vulnerable to risk factors for Autism Spectrum Disorders (ASDs), which include loss or mutations of synaptic proteins and environmental insults, such as dietary zinc deficiency. Here, we show how Shank2 and Shank3 mediate a zinc-dependent regulation of AMPAR function and subunit switch from GluA2-lacking to GluA2-containing AMPARs. Over development, we found a concomitant increase in Shank2 and Shank3 with GluA2 at synapses, implicating these molecules as potential players in AMPAR maturation. Since Shank activation and function require zinc, we next studied whether neuronal activity regulated postsynaptic zinc at glutamatergic synapses. Zinc was found to increase transiently and reversibly with neuronal depolarization at synapses, which could affect Shank and AMPAR localization and activity. Elevated zinc induced multiple functional changes in AMPAR, indicative of a subunit switch. Specifically, zinc lengthened the decay time of AMPAR-mediated synaptic currents and reduced their inward rectification in young hippocampal neurons. Mechanistically, both Shank2 and Shank3 were necessary for the zinc-sensitive enhancement of AMPAR-mediated synaptic transmission and act in concert to promote removal of GluA1 while enhancing recruitment of GluA2 at pre-existing Shank puncta. These findings highlight a cooperative local dynamic regulation of AMPAR subunit switch controlled by zinc signaling through Shank2 and Shank3 to shape the biophysical properties of developing glutamatergic synapses. Given the zinc sensitivity of young neurons and its dependence on Shank2 and Shank3, genetic mutations and/or environmental insults during early development could impair synaptic maturation and circuit formation that underlie ASD etiology.
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Affiliation(s)
- Huong T T Ha
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States.,Neurosciences Graduate Program, School of Medicine, Stanford University, Stanford, CA, United States
| | - Sergio Leal-Ortiz
- Department of Material Science & Engineering, School of Engineering, Stanford University, Stanford, CA, United States
| | - Kriti Lalwani
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
| | - Shigeki Kiyonaka
- Department of Synthetic Chemistry & Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Itaru Hamachi
- Department of Synthetic Chemistry & Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Shreesh P Mysore
- Department of Psychological & Brain Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - John R Huguenard
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
| | - Sally A Kim
- Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States
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4
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Lira M, Arancibia D, Orrego PR, Montenegro-Venegas C, Cruz Y, García J, Leal-Ortiz S, Godoy JA, Gundelfinger ED, Inestrosa NC, Garner CC, Zamorano P, Torres VI. The Exocyst Component Exo70 Modulates Dendrite Arbor Formation, Synapse Density, and Spine Maturation in Primary Hippocampal Neurons. Mol Neurobiol 2018; 56:4620-4638. [DOI: 10.1007/s12035-018-1378-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 10/01/2018] [Indexed: 02/07/2023]
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5
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Edgington R, Spillane KM, Papageorgiou G, Wray W, Ishiwata H, Labarca M, Leal-Ortiz S, Reid G, Webb M, Foord J, Melosh N, Schaefer AT. Functionalisation of Detonation Nanodiamond for Monodispersed, Soluble DNA-Nanodiamond Conjugates Using Mixed Silane Bead-Assisted Sonication Disintegration. Sci Rep 2018; 8:728. [PMID: 29335424 PMCID: PMC5768878 DOI: 10.1038/s41598-017-18601-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 12/07/2017] [Indexed: 01/06/2023] Open
Abstract
Nanodiamonds have many attractive properties that make them suitable for a range of biological applications, but their practical use has been limited because nanodiamond conjugates tend to aggregate in solution during or after functionalisation. Here we demonstrate the production of DNA-detonation nanodiamond (DNA-DND) conjugates with high dispersion and solubility using an ultrasonic, mixed-silanization chemistry protocol based on the in situ Bead-Assisted Sonication Disintegration (BASD) silanization method. We use two silanes to achieve these properties: (1) 3-(trihydroxysilyl)propyl methylphosphonate (THPMP); a negatively charged silane that imparts high zeta potential and solubility in solution; and (2) (3-aminopropyl)triethoxysilane (APTES); a commonly used functional silane that contributes an amino group for subsequent bioconjugation. We target these amino groups for covalent conjugation to thiolated, single-stranded DNA oligomers using the heterobifunctional crosslinker sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (Sulfo-SMCC). The resulting DNA-DND conjugates are the smallest reported to date, as determined by Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). The functionalisation method we describe is versatile and can be used to produce a wide variety of soluble DND-biomolecule conjugates.
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Affiliation(s)
- Robert Edgington
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK. .,Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305, United States. .,Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
| | - Katelyn M Spillane
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK.,Department of Physics, King's College London, London, WC2R 5 2LS, United Kingdom
| | | | - William Wray
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK.,Department of Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Hitoshi Ishiwata
- Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305, United States
| | - Mariana Labarca
- Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305, United States
| | - Sergio Leal-Ortiz
- Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305, United States
| | - Gordon Reid
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK
| | - Martin Webb
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK
| | - John Foord
- Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK
| | - Nicholas Melosh
- Department of Materials Science and Engineering, Stanford University, Stanford, California, 94305, United States.
| | - Andreas T Schaefer
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK. .,Department of Neuroscience, Physiology & Pharmacology, University College London, London, UK.
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6
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Okerlund ND, Schneider K, Leal-Ortiz S, Montenegro-Venegas C, Kim SA, Garner LC, Waites CL, Gundelfinger ED, Reimer RJ, Garner CC. Bassoon Controls Presynaptic Autophagy through Atg5. Neuron 2017; 93:897-913.e7. [DOI: 10.1016/j.neuron.2017.01.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 06/28/2016] [Accepted: 01/25/2017] [Indexed: 12/22/2022]
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7
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Aalipour A, Xu AM, Leal-Ortiz S, Garner CC, Melosh NA. Plasma membrane and actin cytoskeleton as synergistic barriers to nanowire cell penetration. Langmuir 2014; 30:12362-7. [PMID: 25244597 DOI: 10.1021/la502273f] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nanowires are a rapidly emerging platform for manipulation of and material delivery directly into the cell cytosol. These high aspect ratio structures can breach the lipid membrane; however, the yield of penetrant structures is low, and the mechanism is largely unknown. In particular, some nanostructures appear to defeat the membrane transiently, while others can retain long-term access. Here, we examine if local dissolution of the lipid membrane, actin cytoskeleton, or both can enhance nanowire penetration. It is possible that, during cell contact, membrane rupture occurs; however, if the nanostructures do not penetrate the cytoskeleton, the membrane may reclose over a relatively short time frame. We show with quantitative analysis of the number of penetrating nanowires that the lipid bilayer and actin cytoskeleton are synergistic barriers to nanowire cell access, yet chemical poration through both is still insufficient to increase long-term access for adhered cells.
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Affiliation(s)
- Amin Aalipour
- Department of Materials Science and Engineering, Stanford University , 476 Lomita Mall, Stanford, California 94305, United States
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8
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Regus-Leidig H, Fuchs M, Löhner M, Leist SR, Leal-Ortiz S, Chiodo VA, Hauswirth WW, Garner CC, Brandstätter JH. In vivo knockdown of Piccolino disrupts presynaptic ribbon morphology in mouse photoreceptor synapses. Front Cell Neurosci 2014; 8:259. [PMID: 25232303 PMCID: PMC4153300 DOI: 10.3389/fncel.2014.00259] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 08/13/2014] [Indexed: 01/08/2023] Open
Abstract
Piccolo is the largest known cytomatrix protein at active zones of chemical synapses. A growing number of studies on conventional chemical synapses assign Piccolo a role in the recruitment and integration of molecules relevant for both endo- and exocytosis of synaptic vesicles, the dynamic assembly of presynaptic F-actin, as well as the proteostasis of presynaptic proteins, yet a direct function in the structural organization of the active zone has not been uncovered in part due to the expression of multiple alternatively spliced isoforms. We recently identified Piccolino, a Piccolo splice variant specifically expressed in sensory ribbon synapses of the eye and ear. Here we down regulated Piccolino in vivo via an adeno-associated virus-based RNA interference approach and explored the impact on the presynaptic structure of mouse photoreceptor ribbon synapses. Detailed immunocytochemical light and electron microscopical analysis of Piccolino knockdown in photoreceptors revealed a hitherto undescribed photoreceptor ribbon synaptic phenotype with striking morphological changes of synaptic ribbon ultrastructure.
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Affiliation(s)
- Hanna Regus-Leidig
- Department of Biology, Animal Physiology, Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen, Germany
| | - Michaela Fuchs
- Department of Biology, Animal Physiology, Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen, Germany
| | - Martina Löhner
- Department of Biology, Animal Physiology, Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen, Germany
| | - Sarah R Leist
- Department of Biology, Animal Physiology, Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen, Germany ; Department of Infection Genetics, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Sergio Leal-Ortiz
- Department of Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA
| | - Vince A Chiodo
- Department of Ophthalmology, College of Medicine, University of Florida Gainesville, FL, USA
| | - William W Hauswirth
- Department of Ophthalmology, College of Medicine, University of Florida Gainesville, FL, USA
| | - Craig C Garner
- Department of Psychiatry and Behavioral Sciences, Stanford University Palo Alto, CA, USA ; Deutsches Zentrum für Neurodegenerative Erkrankungen Charité, Berlin, Germany
| | - Johann H Brandstätter
- Department of Biology, Animal Physiology, Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen, Germany
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9
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Xie X, Xu AM, Leal-Ortiz S, Cao Y, Garner CC, Melosh NA. Nanostraw-electroporation system for highly efficient intracellular delivery and transfection. ACS Nano 2013; 7:4351-8. [PMID: 23597131 DOI: 10.1021/nn400874a] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nondestructive introduction of genes, proteins, and small molecules into mammalian cells with high efficiency is a challenging, yet critical, process. Here we demonstrate a simple nanoelectroporation platform to achieve highly efficient molecular delivery and high transfection yields with excellent uniformity and cell viability. The system is built on alumina nanostraws extending from a track-etched membrane, forming an array of hollow nanowires connected to an underlying microfluidic channel. Cellular engulfment of the nanostraws provides an intimate contact, significantly reducing the necessary electroporation voltage and increasing homogeneity over a large area. Biomolecule delivery is achieved by diffusion through the nanostraws and enhanced by electrophoresis during pulsing. The system was demonstrated to offer excellent spatial, temporal, and dose control for delivery, as well as providing high-yield cotransfection and sequential transfection.
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Affiliation(s)
- Xi Xie
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
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10
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Hua Z, Leal-Ortiz S, Foss SM, Waites CL, Garner CC, Voglmaier SM, Edwards RH. v-SNARE composition distinguishes synaptic vesicle pools. Neuron 2011; 71:474-87. [PMID: 21835344 DOI: 10.1016/j.neuron.2011.06.010] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2011] [Indexed: 11/29/2022]
Abstract
Synaptic vesicles belong to two distinct pools, a recycling pool responsible for the evoked release of neurotransmitter and a resting pool unresponsive to stimulation. The uniform appearance of synaptic vesicles has suggested that differences in location or cytoskeletal association account for these differences in function. We now find that the v-SNARE tetanus toxin-insensitive vesicle-associated membrane protein (VAMP7) differs from other synaptic vesicle proteins in its distribution to the two pools, providing evidence that they differ in molecular composition. We also find that both resting and recycling pools undergo spontaneous release, and when activated by deletion of the longin domain, VAMP7 influences the properties of release. Further, the endocytosis that follows evoked and spontaneous release differs in mechanism, and specific sequences confer targeting to the different vesicle pools. The results suggest that different endocytic mechanisms generate synaptic vesicles with different proteins that can endow the vesicles with distinct properties.
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Affiliation(s)
- Zhaolin Hua
- Department of Neurology, University of California, San Francisco School of Medicine, San Francisco, CA 94143, USA
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11
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Li D, Specht CG, Waites CL, Butler-Munro C, Leal-Ortiz S, Foote JW, Genoux D, Garner CC, Montgomery JM. SAP97 directs NMDA receptor spine targeting and synaptic plasticity. J Physiol 2011; 589:4491-510. [PMID: 21768261 DOI: 10.1113/jphysiol.2011.215566] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
SAP97 is a multidomain scaffold protein implicated in the forward trafficking and synaptic localization of NMDA- and AMPA-type glutamate receptors. Alternative splicing of SAP97 transcripts gives rise to palmitoylated αSAP97 and L27-domain containing βSAP97 isoforms that differentially regulate the subsynaptic localization of GluR1 subunits of AMPA receptors. Here, we examined whether SAP97 isoforms regulate the mechanisms underlying long-term potentiation (LTP) and depression (LTD) and find that both α- and β-forms of SAP97 impair LTP but enhance LTD via independent isoform-specific mechanisms. Live imaging of α- and βSAP97 revealed that the altered synaptic plasticity was not due to activity-dependent changes in SAP97 localization or exchange kinetics. However, by recording from pairs of synaptically coupled hippocampal neurons, we show that αSAP97 occludes LTP by enhancing the levels of postsynaptic AMPA receptors, while βSAP97 blocks LTP by reducing the synaptic localization of NMDA receptors. Examination of the surface pools of AMPA and NMDA receptors indicates that αSAP97 selectively regulates the synaptic pool of AMPA receptors, whereas βSAP97 regulates the extrasynaptic pools of both AMPA and NMDA receptors. Knockdown of βSAP97 increases the synaptic localization of both AMPA and NMDA receptors, showing that endogenous βSAP97 restricts glutamate receptor expression at excitatory synapses. This isoform-dependent differential regulation of synaptic versus extrasynaptic pools of glutamate receptors will determine how many receptors are available for the induction and the expression of synaptic plasticity. Our data support a model wherein SAP97 isoforms can regulate the ability of synapses to undergo plasticity by controlling the surface distribution of AMPA and NMDA receptors.
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Affiliation(s)
- Dong Li
- Centre for Brain Research and Department of Physiology, University of Auckland, New Zealand
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12
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Torres V, Barra L, Garcés F, Ordenes K, Leal-Ortiz S, Garner CC, Fernandez F, Zamorano P. A bicistronic lentiviral vector based on the 1D/2A sequence of foot-and-mouth disease virus expresses proteins stoichiometrically. J Biotechnol 2010; 146:138-42. [DOI: 10.1016/j.jbiotec.2010.01.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 01/15/2010] [Accepted: 01/25/2010] [Indexed: 11/28/2022]
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13
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Leal-Ortiz S, Waites CL, Terry-Lorenzo R, Zamorano P, Gundelfinger ED, Garner CC. Piccolo modulation of Synapsin1a dynamics regulates synaptic vesicle exocytosis. ACTA ACUST UNITED AC 2008; 181:831-46. [PMID: 18519737 PMCID: PMC2396795 DOI: 10.1083/jcb.200711167] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Active zones are specialized regions of the presynaptic plasma membrane designed for the efficient and repetitive release of neurotransmitter via synaptic vesicle (SV) exocytosis. Piccolo is a high molecular weight component of the active zone that is hypothesized to participate both in active zone formation and the scaffolding of key molecules involved in SV recycling. In this study, we use interference RNAs to eliminate Piccolo expression from cultured hippocampal neurons to assess its involvement in synapse formation and function. Our data show that Piccolo is not required for glutamatergic synapse formation but does influence presynaptic function by negatively regulating SV exocytosis. Mechanistically, this regulation appears to be calmodulin kinase II–dependent and mediated through the modulation of Synapsin1a dynamics. This function is not shared by the highly homologous protein Bassoon, which indicates that Piccolo has a unique role in coupling the mobilization of SVs in the reserve pool to events within the active zone.
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Affiliation(s)
- Sergio Leal-Ortiz
- Deptartment of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, CA 94304, USA
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14
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Sabio G, Reuver S, Feijoo C, Hasegawa M, Thomas GM, Centeno F, Kuhlendahl S, Leal-Ortiz S, Goedert M, Garner C, Cuenda A. Stress- and mitogen-induced phosphorylation of the synapse-associated protein SAP90/PSD-95 by activation of SAPK3/p38gamma and ERK1/ERK2. Biochem J 2004; 380:19-30. [PMID: 14741046 PMCID: PMC1224136 DOI: 10.1042/bj20031628] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2003] [Revised: 01/07/2004] [Accepted: 01/23/2004] [Indexed: 11/17/2022]
Abstract
SAPK3 (stress-activated protein kinase-3, also known as p38gamma) is a member of the mitogen-activated protein kinase family; it phosphorylates substrates in response to cellular stress, and has been shown to bind through its C-terminal sequence to the PDZ domain of alpha1-syntrophin. In the present study, we show that SAP90 [(synapse-associated protein 90; also known as PSD-95 (postsynaptic density-95)] is a novel physiological substrate for both SAPK3/p38gamma and the ERK (extracellular-signal-regulated protein kinase). SAPK3/p38gamma binds preferentially to the third PDZ domain of SAP90 and phosphorylates residues Thr287 and Ser290 in vitro, and Ser290 in cells in response to cellular stresses. Phosphorylation of SAP90 is dependent on the binding of SAPK3/p38gamma to the PDZ domain of SAP90. It is not blocked by SB 203580, which inhibits SAPK2a/p38alpha and SAPK2b/p38beta but not SAPK3/p38gamma, or by the ERK pathway inhibitor PD 184352. However, phosphorylation is abolished when cells are treated with a cell-permeant Tat fusion peptide that disrupts the interaction of SAPK3/p38gamma with SAP90. ERK2 also phosphorylates SAP90 at Thr287 and Ser290 in vitro, but this does not require PDZ-dependent binding. SAP90 also becomes phosphorylated in response to mitogens, and this phosphorylation is prevented by pretreatment of the cells with PD 184352, but not with SB 203580. In neurons, SAP90 and SAPK3/p38gamma co-localize and they are co-immunoprecipitated from brain synaptic junctional preparations. These results demonstrate that SAP90 is a novel binding partner for SAPK3/p38gamma, a first physiological substrate described for SAPK3/p38gamma and a novel substrate for ERK1/ERK2, and that phosphorylation of SAP90 may play a role in regulating protein-protein interactions at the synapse in response to adverse stress- or mitogen-related stimuli.
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Affiliation(s)
- Guadalupe Sabio
- MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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