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Rahav N, Marrero D, Soffer A, Glickman E, Beldjilali-Labro M, Yaffe Y, Tadmor K, Leichtmann-Bardoogo Y, Ashery U, Maoz BM. Multi-Sensor Origami Platform: A Customizable System for Obtaining Spatiotemporally Precise Functional Readouts in 3D Models. Adv Sci (Weinh) 2024:e2305555. [PMID: 38634605 DOI: 10.1002/advs.202305555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 03/14/2024] [Indexed: 04/19/2024]
Abstract
Bioprinting technology offers unprecedented opportunities to construct in vitro tissue models that recapitulate the 3D morphology and functionality of native tissue. Yet, it remains difficult to obtain adequate functional readouts from such models. In particular, it is challenging to position sensors in desired locations within pre-fabricated 3D bioprinted structures. At the same time, bioprinting tissue directly onto a sensing device is not feasible due to interference with the printer head. As such, a multi-sensing platform inspired by origami that overcomes these challenges by "folding" around a separately fabricated 3D tissue structure is proposed, allowing for the insertion of electrodes into precise locations, which are custom-defined using computer-aided-design software. The multi-sensing origami platform (MSOP) can be connected to a commercial multi-electrode array (MEA) system for data-acquisition and processing. To demonstrate the platform, how integrated 3D MEA electrodes can record neuronal electrical activity in a 3D model of a neurovascular unit is shown. The MSOP also enables a microvascular endothelial network to be cultured separately and integrated with the 3D tissue structure. Accordingly, how impedance-based sensors in the platform can measure endothelial barrier function is shown. It is further demonstrated the device's versatility by using it to measure neuronal activity in brain organoids.
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Affiliation(s)
- Noam Rahav
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Denise Marrero
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Campus UAB, Bellaterra, Barcelona, 08193, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería Biomateriales y Nanomedicina, Madrid, 50018, Spain
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Adi Soffer
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Emma Glickman
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | | | - Yakey Yaffe
- Sagol Center for Regenerative Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Keshet Tadmor
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | | | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol Center for Regenerative Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ben M Maoz
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol Center for Regenerative Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, 69978, Israel
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2
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Jiang SZ, Shahoha M, Zhang HY, Brancaleone W, Elkahloun A, Tejeda HA, Ashery U, Eiden LE. The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation. Cell Mol Life Sci 2024; 81:48. [PMID: 38236296 DOI: 10.1007/s00018-023-04999-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/16/2023] [Accepted: 10/04/2023] [Indexed: 01/19/2024]
Abstract
The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.
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Affiliation(s)
- Sunny Zhihong Jiang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - Meishar Shahoha
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel
| | - Hai-Ying Zhang
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | - William Brancaleone
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA
| | | | - Hugo A Tejeda
- Unit on Neuromodulation and Synaptic Integration, NIMH-IRP, Bethesda, MD, USA
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, and Sagol School of Neuroscience, Tel Aviv University, Sherman Building Rm 719, Ramat Aviv, 69978, Tel Aviv, Israel.
| | - Lee E Eiden
- Section On Molecular Neuroscience, NIMH Intramural Research Program, 9000 Rockville Pike, Building 49, Room 5A38, Bethesda, MD, 20892, USA.
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Twitto-Greenberg R, Liraz-Zaltsman S, Michaelson DM, Liraz O, Lubitz I, Atrakchi-Baranes D, Shemesh C, Ashery U, Cooper I, Harari A, Harats D, Schnaider-Beeri M, Shaish A. 9-cis beta-carotene-enriched diet significantly improved cognition and decreased Alzheimer's disease neuropathology and neuroinflammation in Alzheimer's disease-like mouse models. Neurobiol Aging 2024; 133:16-27. [PMID: 38381472 DOI: 10.1016/j.neurobiolaging.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 09/10/2023] [Accepted: 09/17/2023] [Indexed: 02/22/2024]
Abstract
A significant progressive decline in beta-carotene (βC) levels in the brain is associated with cognitive impairment and a higher prevalence of Alzheimer's disease (AD). In this study, we investigated whether the administration of 9-cis beta-carotene (9CBC)-rich powder of the alga Dunaliella bardawil, the best-known source of βC in nature, inhibits the development of AD-like neuropathology and cognitive deficits. We demonstrated that in 3 AD mouse models, Tg2576, 5xFAD, and apoE4, 9CBC treatment improved long- and short-term memory, decreased neuroinflammation, and reduced the prevalence of β-amyloid plaques and tau hyperphosphorylation. These findings suggest that 9CBC has the potential to be an effective preventive and symptomatic AD therapy.
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Affiliation(s)
- Rachel Twitto-Greenberg
- The Bert W. Strassburger Metabolic Center, Sheba Medical Center, Ramat-Gan, Israel; The Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel; The Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-Gan, Israel
| | - Sigal Liraz-Zaltsman
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-Gan, Israel; Department of Pharmacology, Institute for Drug Research, Hebrew University, Jerusalem, Israel; Institutes for Health and Medical Professions, Department of Sports Therapy, Ono Academic College, Kyrat-Ono, Israel
| | - Daniel M Michaelson
- The Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Ori Liraz
- The Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Irit Lubitz
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-Gan, Israel
| | | | - Chen Shemesh
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-Gan, Israel
| | - Uri Ashery
- The Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Itzik Cooper
- The Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-Gan, Israel; Institutes for Health and Medical Professions, Department of Sports Therapy, Ono Academic College, Kyrat-Ono, Israel
| | - Ayelet Harari
- The Bert W. Strassburger Metabolic Center, Sheba Medical Center, Ramat-Gan, Israel
| | - Dror Harats
- The Bert W. Strassburger Metabolic Center, Sheba Medical Center, Ramat-Gan, Israel; The Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | | | - Aviv Shaish
- The Bert W. Strassburger Metabolic Center, Sheba Medical Center, Ramat-Gan, Israel; Department of Life Sciences, Achva Academic College, Be'er-Tuvia Regional Council, Israel.
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4
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Sela M, Poley M, Mora-Raimundo P, Kagan S, Avital A, Kaduri M, Chen G, Adir O, Rozencweig A, Weiss Y, Sade O, Leichtmann-Bardoogo Y, Simchi L, Aga-Mizrachi S, Bell B, Yeretz-Peretz Y, Zaid Or A, Choudhary A, Rosh I, Cordeiro D, Cohen-Adiv S, Berdichevsky Y, Odeh A, Shklover J, Shainsky-Roitman J, Schroeder JE, Hershkovitz D, Hasson P, Ashkenazi A, Stern S, Laviv T, Ben-Zvi A, Avital A, Ashery U, Maoz BM, Schroeder A. Brain-Targeted Liposomes Loaded with Monoclonal Antibodies Reduce Alpha-Synuclein Aggregation and Improve Behavioral Symptoms in Parkinson's Disease. Adv Mater 2023; 35:e2304654. [PMID: 37753928 PMCID: PMC7615408 DOI: 10.1002/adma.202304654] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [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: 05/17/2023] [Revised: 09/04/2023] [Indexed: 09/28/2023]
Abstract
Monoclonal antibodies (mAbs) hold promise in treating Parkinson's disease (PD), although poor delivery to the brain hinders their therapeutic application. In the current study, it is demonstrated that brain-targeted liposomes (BTL) enhance the delivery of mAbs across the blood-brain-barrier (BBB) and into neurons, thereby allowing the intracellular and extracellular treatment of the PD brain. BTL are decorated with transferrin to improve brain targeting through overexpressed transferrin-receptors on the BBB during PD. BTL are loaded with SynO4, a mAb that inhibits alpha-synuclein (AS) aggregation, a pathological hallmark of PD. It is shown that 100-nm BTL cross human BBB models intact and are taken up by primary neurons. Within neurons, SynO4 is released from the nanoparticles and bound to its target, thereby reducing AS aggregation, and enhancing neuronal viability. In vivo, intravenous BTL administration results in a sevenfold increase in mAbs in brain cells, decreasing AS aggregation and neuroinflammation. Treatment with BTL also improve behavioral motor function and learning ability in mice, with a favorable safety profile. Accordingly, targeted nanotechnologies offer a valuable platform for drug delivery to treat brain neurodegeneration.
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Affiliation(s)
- Mor Sela
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Maria Poley
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Patricia Mora-Raimundo
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Shaked Kagan
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Aviram Avital
- The Norman Seiden Multidisciplinary Program for Nanoscience and Nanotechnology, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Maya Kaduri
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Gal Chen
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
- The Interdisciplinary Program for Biotechnology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Omer Adir
- The Norman Seiden Multidisciplinary Program for Nanoscience and Nanotechnology, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Adi Rozencweig
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Yfat Weiss
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ofir Sade
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | | | - Lilach Simchi
- Department of Occupational Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa 3498838, Israel
| | - Shlomit Aga-Mizrachi
- Department of Occupational Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa 3498838, Israel
| | - Batia Bell
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9190500, Israel
| | - Yoel Yeretz-Peretz
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9190500, Israel
| | - Aviv Zaid Or
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ashwani Choudhary
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Idan Rosh
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Diogo Cordeiro
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Stav Cohen-Adiv
- The Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yevgeny Berdichevsky
- The Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anas Odeh
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Jeny Shklover
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Janna Shainsky-Roitman
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Joshua E. Schroeder
- Spine Unit, Orthopedic Complex, Hadassah Hebrew University Medical Center, Kiryat Hadassah, POB 12000, Jerusalem 9190500, Israel
| | - Dov Hershkovitz
- Department of Pathology, Tel Aviv Sourasky Medical Center, Tel Aviv 6997801, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Peleg Hasson
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
| | - Avraham Ashkenazi
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- The Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shani Stern
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Tal Laviv
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ayal Ben-Zvi
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9190500, Israel
| | - Avi Avital
- Department of Occupational Therapy, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa 3498838, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ben M. Maoz
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 6997801, Israel
- Sagol Center for Regenerative Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Avi Schroeder
- The Louis Family Laboratory for Targeted Drug Delivery and Personalized Medicine Technologies, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
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5
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Sade O, Boneberg R, Weiss Y, Beldjilali-Labro M, Leichtmann-Bardoogo Y, Talpir I, Gottfried I, Ashery U, Rauti R, Maoz BM. Super-Resolution-Chip: an in-vitro platform that enables super-resolution microscopy of co-cultures and 3D systems. Biomed Opt Express 2023; 14:5223-5237. [PMID: 37854575 PMCID: PMC10581794 DOI: 10.1364/boe.498038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/06/2023] [Accepted: 08/12/2023] [Indexed: 10/20/2023]
Abstract
The development of organs-on-a-chip platforms has revolutionized in-vitro cellular culture by allowing cells to be grown in an environment that better mimics human physiology. However, there is still a challenge in integrating those platforms with advanced imaging technology. This is extremely important when we want to study molecular changes and subcellular processes on the level of a single molecule using super-resolution microscopy (SRM), which has a resolution beyond the diffraction limit of light. Currently, existing platforms that include SRM have certain limitations, either as they only support 2D monocultures, without flow or as they demand a lot of production and handling. In this study, we developed a Super-Res-Chip platform, consisting of a 3D-printed chip and a porous membrane, that could be used to co-culture cells in close proximity either in 2D or in 3D while allowing SRM on both sides of the membrane. To demonstrate the functionality of the device, we co-cultured in endothelial and epithelial cells and used direct stochastic optical reconstruction microscopy (dSTORM) to investigate how glioblastoma cells affect the expression of the gap-junction protein Connexin43 in endothelial cells grown in 2D and in 3D. Cluster analysis of Connexin43 distribution revealed no difference in the number of clusters, their size, or radii, but did identify differences in their density. Furthermore, the spatial resolution was high also when the cells were imaged through the membrane (20-30 nm for x-y) and 10-20 nm when imaged directly both for 2D and 3D conditions. Overall, this chip allows to characterize of complex cellular processes on a molecular scale in an easy manner and improved the capacity for imaging in a single molecule resolution complex cellular organization.
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Affiliation(s)
- Ofir Sade
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ronja Boneberg
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Yifat Weiss
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | | | | | - Itay Talpir
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Irit Gottfried
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Rossana Rauti
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, 61029, Italy
| | - Ben M Maoz
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, 69978, Israel
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6
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Shahoha M, Cohen R, Ben-Simon Y, Ashery U. cAMP-Dependent Synaptic Plasticity at the Hippocampal Mossy Fiber Terminal. Front Synaptic Neurosci 2022; 14:861215. [PMID: 35444523 PMCID: PMC9013808 DOI: 10.3389/fnsyn.2022.861215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 01/24/2022] [Accepted: 02/23/2022] [Indexed: 11/24/2022] Open
Abstract
Cyclic adenosine monophosphate (cAMP) is a crucial second messenger involved in both pre- and postsynaptic plasticity in many neuronal types across species. In the hippocampal mossy fiber (MF) synapse, cAMP mediates presynaptic long-term potentiation and depression. The main cAMP-dependent signaling pathway linked to MF synaptic plasticity acts via the activation of the protein kinase A (PKA) molecular cascade. Accordingly, various downstream putative synaptic PKA target proteins have been linked to cAMP-dependent MF synaptic plasticity, such as synapsin, rabphilin, synaptotagmin-12, RIM1a, tomosyn, and P/Q-type calcium channels. Regulating the expression of some of these proteins alters synaptic release probability and calcium channel clustering, resulting in short- and long-term changes to synaptic efficacy. However, despite decades of research, the exact molecular mechanisms by which cAMP and PKA exert their influences in MF terminals remain largely unknown. Here, we review current knowledge of different cAMP catalysts and potential downstream PKA-dependent molecular cascades, in addition to non-canonical cAMP-dependent but PKA-independent cascades, which might serve as alternative, compensatory or competing pathways to the canonical PKA cascade. Since several other central synapses share a similar form of presynaptic plasticity with the MF, a better description of the molecular mechanisms governing MF plasticity could be key to understanding the relationship between the transcriptional and computational levels across brain regions.
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Affiliation(s)
- Meishar Shahoha
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ronni Cohen
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Yoav Ben-Simon
- Department of Neurophysiology, Vienna Medical University, Vienna, Austria
- *Correspondence: Yoav Ben-Simon,
| | - Uri Ashery
- Faculty of Life Sciences, School of Neurobiology, Biochemistry and Biophysics, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Uri Ashery,
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7
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Rauti R, Shahoha M, Leichtmann-Bardoogo Y, Nasser R, Paz E, Tamir R, Miller V, Babich T, Shaked K, Ehrlich A, Ioannidis K, Nahmias Y, Sharan R, Ashery U, Maoz BM. Effect of SARS-CoV-2 proteins on vascular permeability. eLife 2021; 10:69314. [PMID: 34694226 PMCID: PMC8545399 DOI: 10.7554/elife.69314] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [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: 04/12/2021] [Accepted: 10/09/2021] [Indexed: 12/13/2022] Open
Abstract
Severe acute respiratory syndrome (SARS)-CoV-2 infection leads to severe disease associated with cytokine storm, vascular dysfunction, coagulation, and progressive lung damage. It affects several vital organs, seemingly through a pathological effect on endothelial cells. The SARS-CoV-2 genome encodes 29 proteins, whose contribution to the disease manifestations, and especially endothelial complications, is unknown. We cloned and expressed 26 of these proteins in human cells and characterized the endothelial response to overexpression of each, individually. Whereas most proteins induced significant changes in endothelial permeability, nsp2, nsp5_c145a (catalytic dead mutant of nsp5), and nsp7 also reduced CD31, and increased von Willebrand factor expression and IL-6, suggesting endothelial dysfunction. Using propagation-based analysis of a protein–protein interaction (PPI) network, we predicted the endothelial proteins affected by the viral proteins that potentially mediate these effects. We further applied our PPI model to identify the role of each SARS-CoV-2 protein in other tissues affected by coronavirus disease (COVID-19). While validating the PPI network model, we found that the tight junction (TJ) proteins cadherin-5, ZO-1, and β-catenin are affected by nsp2, nsp5_c145a, and nsp7 consistent with the model prediction. Overall, this work identifies the SARS-CoV-2 proteins that might be most detrimental in terms of endothelial dysfunction, thereby shedding light on vascular aspects of COVID-19.
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Affiliation(s)
- Rossana Rauti
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Meishar Shahoha
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | | | - Rami Nasser
- Blavatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Eyal Paz
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Rina Tamir
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Victoria Miller
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Tal Babich
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Kfir Shaked
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Avner Ehrlich
- Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Yaakov Nahmias
- Grass Center for Bioengineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Roded Sharan
- Blavatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.,The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Ben Meir Maoz
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.,The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
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8
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Gottfried I, Schottlender N, Ashery U. Hyperbaric Oxygen Treatment-From Mechanisms to Cognitive Improvement. Biomolecules 2021; 11:biom11101520. [PMID: 34680155 PMCID: PMC8533945 DOI: 10.3390/biom11101520] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/06/2021] [Accepted: 10/13/2021] [Indexed: 12/19/2022] Open
Abstract
Hyperbaric oxygen treatment (HBOT)—the medical use of oxygen at environmental pressure greater than one atmosphere absolute—is a very effective therapy for several approved clinical situations, such as carbon monoxide intoxication, incurable diabetes or radiation-injury wounds, and smoke inhalation. In recent years, it has also been used to improve cognition, neuro-wellness, and quality of life following brain trauma and stroke. This opens new avenues for the elderly, including the treatment of neurological and neurodegenerative diseases and improvement of cognition and brain metabolism in cases of mild cognitive impairment. Alongside its integration into clinics, basic research studies have elucidated HBOT’s mechanisms of action and its effects on cellular processes, transcription factors, mitochondrial function, oxidative stress, and inflammation. Therefore, HBOT is becoming a major player in 21st century research and clinical treatments. The following review will discuss the basic mechanisms of HBOT, and its effects on cellular processes, cognition, and brain disorders.
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Affiliation(s)
- Irit Gottfried
- School of Neurobiology, Biochemistry and Biophysics, Life Sciences Faculty, Tel Aviv University, Tel Aviv 6997801, Israel; (I.G.); (N.S.)
| | - Nofar Schottlender
- School of Neurobiology, Biochemistry and Biophysics, Life Sciences Faculty, Tel Aviv University, Tel Aviv 6997801, Israel; (I.G.); (N.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, Life Sciences Faculty, Tel Aviv University, Tel Aviv 6997801, Israel; (I.G.); (N.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Correspondence: ; Tel.: +972-3-6409827
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9
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Shapira R, Gdalyahu A, Gottfried I, Sasson E, Hadanny A, Efrati S, Blinder P, Ashery U. Hyperbaric oxygen therapy alleviates vascular dysfunction and amyloid burden in an Alzheimer's disease mouse model and in elderly patients. Aging (Albany NY) 2021; 13:20935-20961. [PMID: 34499614 PMCID: PMC8457592 DOI: 10.18632/aging.203485] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 08/10/2021] [Indexed: 04/21/2023]
Abstract
Vascular dysfunction is entwined with aging and in the pathogenesis of Alzheimer's disease (AD) and contributes to reduced cerebral blood flow (CBF) and consequently, hypoxia. Hyperbaric oxygen therapy (HBOT) is in clinical use for a wide range of medical conditions. In the current study, we exposed 5XFAD mice, a well-studied AD model that presents impaired cognitive abilities, to HBOT and then investigated the therapeutical effects using two-photon live animal imaging, behavioral tasks, and biochemical and histological analysis. HBOT increased arteriolar luminal diameter and elevated CBF, thus contributing to reduced hypoxia. Furthermore, HBOT reduced amyloid burden by reducing the volume of pre-existing plaques and attenuating the formation of new ones. This was associated with changes in amyloid precursor protein processing, elevated degradation and clearance of Aß protein and improved behavior of 5XFAD mice. Hence, our findings are consistent with the effects of HBOT being mediated partially through a persistent structural change in blood vessels that reduces brain hypoxia. Motivated by these findings, we exposed elderly patients with significant memory loss at baseline to HBOT and observed an increase in CBF and improvement in cognitive performances. This study demonstrates HBOT efficacy in hypoxia-related neurological conditions, particularly in AD and aging.
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Affiliation(s)
- Ronit Shapira
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Amos Gdalyahu
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Irit Gottfried
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
| | - Efrat Sasson
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Amir Hadanny
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Shai Efrati
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
- Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel
- Sagol Center for Hyperbaric Medicine and Research, Assaf Harofeh Medical Center, Be’er Ya’akov, Israel
| | - Pablo Blinder
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel-Aviv, Israel
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10
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Shvarts-Serebro I, Sheinin A, Gottfried I, Adler L, Schottlender N, Ashery U, Barak B. miR-128 as a Regulator of Synaptic Properties in 5xFAD Mice Hippocampal Neurons. J Mol Neurosci 2021; 71:2593-2607. [PMID: 34151409 DOI: 10.1007/s12031-021-01862-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022]
Abstract
Alzheimer's disease (AD) is characterized by progressive synaptic dysfunction, deterioration of neuronal transmission, and consequently neuronal death. Although there is no treatment for AD, exposure to enriched environment (EE) in mice, as well as physical and mental activity in human subjects have been shown to have a protective effect by slowing the disease's progression and reducing AD-like cognitive impairment. However, the molecular mechanism of this mitigating effect is still not understood. One of the mechanisms that has recently been shown to be involved in neuronal degeneration is microRNAs (miRNAs) regulation, which act as a post-transcriptional regulators of gene expression. miR-128 has been shown to be significantly altered in individuals with AD and in mice following exposure to EE. Here, we focused on elucidating the possible role of miR-128 in AD pathology and found that miR-128 regulates the expression of two proteins essential for synaptic transmission, SNAP-25, and synaptotagmin1 (Syt1). Clinically relevant, in 5xFAD mouse model for AD, this miRNA's expression was found as downregulated, resembling the alteration found in the hippocampi of individuals with AD. Interestingly, exposing WT mice to EE also resulted in downregulation of miR-128 expression levels, although EE and AD conditions demonstrate opposing effects on neuronal functioning and synaptic plasticity. We also found that miR-128 expression downregulation in primary hippocampal cultures from 5xFAD mice results in increased neuronal network activity and neuronal excitability. Altogether, our findings place miR-128 as a synaptic player that may contribute to synaptic functioning and plasticity through regulation of synaptic protein expression and function.
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Affiliation(s)
| | - Anton Sheinin
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Irit Gottfried
- The School of Neurobiology, Biochemistry and Biophysics, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Lior Adler
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Nofar Schottlender
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.,The School of Neurobiology, Biochemistry and Biophysics, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel. .,The School of Neurobiology, Biochemistry and Biophysics, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
| | - Boaz Barak
- The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel. .,The School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel.
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11
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Wegrzynowicz M, Bar-On D, Calo' L, Anichtchik O, Iovino M, Xia J, Ryazanov S, Leonov A, Giese A, Dalley JW, Griesinger C, Ashery U, Spillantini MG. Depopulation of dense α-synuclein aggregates is associated with rescue of dopamine neuron dysfunction and death in a new Parkinson's disease model. Acta Neuropathol 2019; 138:575-595. [PMID: 31165254 PMCID: PMC6778064 DOI: 10.1007/s00401-019-02023-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/20/2019] [Accepted: 04/30/2019] [Indexed: 12/13/2022]
Abstract
Parkinson’s disease (PD) is characterized by the presence of α-synuclein aggregates known as Lewy bodies and Lewy neurites, whose formation is linked to disease development. The causal relation between α-synuclein aggregates and PD is not well understood. We generated a new transgenic mouse line (MI2) expressing human, aggregation-prone truncated 1–120 α-synuclein under the control of the tyrosine hydroxylase promoter. MI2 mice exhibit progressive aggregation of α-synuclein in dopaminergic neurons of the substantia nigra pars compacta and their striatal terminals. This is associated with a progressive reduction of striatal dopamine release, reduced striatal innervation and significant nigral dopaminergic nerve cell death starting from 6 and 12 months of age, respectively. In the MI2 mice, alterations in gait impairment can be detected by the DigiGait test from 9 months of age, while gross motor deficit was detected by rotarod test at 20 months of age when 50% of dopaminergic neurons in the substantia nigra pars compacta are lost. These changes were associated with an increase in the number and density of 20–500 nm α-synuclein species as shown by dSTORM. Treatment with the oligomer modulator anle138b, from 9 to 12 months of age, restored striatal dopamine release, prevented dopaminergic cell death and gait impairment. These effects were associated with a reduction of the inner density of large α-synuclein aggregates and an increase in dispersed small α-synuclein species as revealed by dSTORM. The MI2 mouse model recapitulates the progressive dopaminergic deficit observed in PD, showing that early synaptic dysfunction is associated to fine behavioral motor alterations, precedes dopaminergic axonal loss and neuronal death that become associated with a more consistent motor deficit upon reaching a certain threshold. Our data also provide new mechanistic insight for the effect of anle138b’s function in vivo supporting that targeting α-synuclein aggregation is a promising therapeutic approach for PD.
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Affiliation(s)
- Michal Wegrzynowicz
- Department of Clinical Neurosciences, University of Cambridge, The Clifford Allbutt Building, Cambridge, CB2 0AH, UK
| | - Dana Bar-On
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Laura Calo'
- Department of Clinical Neurosciences, University of Cambridge, The Clifford Allbutt Building, Cambridge, CB2 0AH, UK
| | - Oleg Anichtchik
- Department of Clinical Neurosciences, University of Cambridge, The Clifford Allbutt Building, Cambridge, CB2 0AH, UK
| | - Mariangela Iovino
- Department of Clinical Neurosciences, University of Cambridge, The Clifford Allbutt Building, Cambridge, CB2 0AH, UK
| | - Jing Xia
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
| | - Sergey Ryazanov
- Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- DFG Research Centre Nanoscale Microscopy and Molecular Physiology of the Brain, 37070, Göttingen, Germany
| | - Andrei Leonov
- Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- DFG Research Centre Nanoscale Microscopy and Molecular Physiology of the Brain, 37070, Göttingen, Germany
| | - Armin Giese
- Center for Neuropathology and Prion Research, Ludwig Maximilians University Munich, 81377, Munich, Germany
| | - Jeffrey W Dalley
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Department of Psychiatry, University of Cambridge, Cambridge, CB2 2SZ, UK
| | - Christian Griesinger
- Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- DFG Research Centre Nanoscale Microscopy and Molecular Physiology of the Brain, 37070, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Uri Ashery
- School of Neurobiology, Biochemistry and Biophysics, George S. Wise Faculty of Life Sciences, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Maria Grazia Spillantini
- Department of Clinical Neurosciences, University of Cambridge, The Clifford Allbutt Building, Cambridge, CB2 0AH, UK.
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12
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Perets N, Betzer O, Shapira R, Brenstein S, Angel A, Sadan T, Ashery U, Popovtzer R, Offen D. Golden Exosomes Selectively Target Brain Pathologies in Neurodegenerative and Neurodevelopmental Disorders. Nano Lett 2019; 19:3422-3431. [PMID: 30761901 DOI: 10.1021/acs.nanolett.8b04148] [Citation(s) in RCA: 214] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Exosomes, nanovesicles that are secreted by different cell types, enable intercellular communication at local or distant sites. Alhough they have been found to cross the blood brain barrier, their migration and homing abilities within the brain remain unstudied. We have recently developed a method for longitudinal and quantitative in vivo neuroimaging of exosomes based on the superior visualization abilities of classical X-ray computed tomography (CT), combined with gold nanoparticles as labeling agents. Here, we used this technique to track the migration and homing patterns of intranasally administrated exosomes derived from bone marrow mesenchymal stem cells (MSC-exo) in different brain pathologies, including stroke, autism, Parkinson's disease, and Alzheimer's disease. We found that MSC-exo specifically targeted and accumulated in pathologically relevant murine models brains regions up to 96 h post administration, while in healthy controls they showed a diffuse migration pattern and clearance by 24 h. The neuro-inflammatory signal in pathological brains was highly correlated with MSC-exo accumulation, suggesting that the homing mechanism is inflammatory-driven. In addition, MSC-exo were selectively uptaken by neuronal cells, but not glial cells, in the pathological regions. Taken together, these findings can significantly promote the application of exosomes for therapy and targeted drug delivery in various brain pathologies.
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Affiliation(s)
- Nisim Perets
- Sagol School of Neuroscience , Tel Aviv University , Tel Aviv 6997801 , Israel
- Sacklar School of Medicine, Department of Human Genetics and Biochemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Oshra Betzer
- Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat Gan 5290002 , Israel
| | - Ronit Shapira
- School of Neurobiology, Biochemistry and Biophysics, Life Sciences Faculty , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Shmuel Brenstein
- Sagol School of Neuroscience , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Ariel Angel
- Sagol School of Neuroscience , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Tamar Sadan
- Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat Gan 5290002 , Israel
| | - Uri Ashery
- Sagol School of Neuroscience , Tel Aviv University , Tel Aviv 6997801 , Israel
- School of Neurobiology, Biochemistry and Biophysics, Life Sciences Faculty , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Rachela Popovtzer
- Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat Gan 5290002 , Israel
| | - Daniel Offen
- Sagol School of Neuroscience , Tel Aviv University , Tel Aviv 6997801 , Israel
- Sacklar School of Medicine, Department of Human Genetics and Biochemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
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13
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Offen D, Perets N, Betzer O, Popovtzer R, Shapira R, Ashery U. Targeting damages in the brain: exosomes derived from MSC present migration and homing abilities to different neurodegenerative and neuropsychiatric locations. Cytotherapy 2019. [DOI: 10.1016/j.jcyt.2019.04.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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14
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Shapira R, Solomon B, Efrati S, Frenkel D, Ashery U. Hyperbaric oxygen therapy ameliorates pathophysiology of 3xTg-AD mouse model by attenuating neuroinflammation. Neurobiol Aging 2018; 62:105-119. [DOI: 10.1016/j.neurobiolaging.2017.10.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 10/04/2017] [Accepted: 10/06/2017] [Indexed: 12/25/2022]
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15
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Affiliation(s)
- Ronit Shapira
- Department of Neurobiology, the George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Shai Efrati
- Sackler School of Medicine, Tel Aviv University; Sagol Center for Hyperbaric Medicine & Research, Assaf Harofeh Medical Center, Israel
| | - Uri Ashery
- Department of Neurobiology, the George S. Wise Faculty of Life Sciences; Sagol School of Neuroscience, Tel Aviv University, Israel
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16
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Michaeli L, Gottfried I, Bykhovskaia M, Ashery U. Phosphatidylinositol (4, 5)-bisphosphate targets double C2 domain protein B to the plasma membrane. Traffic 2017; 18:825-839. [PMID: 28941037 DOI: 10.1111/tra.12528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 01/05/2023]
Abstract
Double C2 domain protein B (DOC2B) is a high-affinity Ca2+ sensor that translocates from the cytosol to the plasma membrane (PM) and promotes vesicle priming and fusion. However, the molecular mechanism underlying its translocation and targeting to the PM in living cells is not completely understood. DOC2B interacts in vitro with the PM components phosphatidylserine, phosphatidylinositol (4, 5)-bisphosphate [PI(4, 5)P2 ] and target SNAREs (t-SNAREs). Here, we show that PI(4, 5)P2 hydrolysis at the PM of living cells abolishes DOC2B translocation, whereas manipulations of t-SNAREs and other phosphoinositides have no effect. Moreover, we were able to redirect DOC2B to intracellular membranes by synthesizing PI(4, 5)P2 in those membranes. Molecular dynamics simulations and mutagenesis in the calcium and PI(4, 5)P2 -binding sites strengthened our findings, demonstrating that both calcium and PI(4, 5)P2 are required for the DOC2B-PM association and revealing multiple PI(4, 5)P2 -C2B interactions. In addition, we show that DOC2B translocation to the PM is ATP-independent and occurs in a diffusion-like manner. Our data suggest that the Ca2+ -triggered translocation of DOC2B is diffusion-driven and aimed at PI(4, 5)P2 -containing membranes.
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Affiliation(s)
- Lirin Michaeli
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Irit Gottfried
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | | | - Uri Ashery
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
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17
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Bielopolski N, Lam AD, Bar-On D, Sauer M, Stuenkel EL, Ashery U. Differential interaction of tomosyn with syntaxin and SNAP25 depends on domains in the WD40 β-propeller core and determines its inhibitory activity. J Biol Chem 2014; 289:17087-99. [PMID: 24782308 DOI: 10.1074/jbc.m113.515296] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal exocytosis depends on efficient formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes and is regulated by tomosyn, a SNARE-binding protein. To gain new information about tomosyn's activity, we characterized its mobility and organization on the plasma membrane (PM) in relation to other SNARE proteins and inhibition of exocytosis. By using direct stochastic optical reconstruction microscopy (dSTORM), we found tomosyn to be organized in small clusters adjacent to syntaxin clusters. In addition, we show that tomosyn is present in both syntaxin-tomosyn complexes and syntaxin-SNAP25-tomosyn complexes. Tomosyn mutants that lack residues 537-578 or 897-917 from its β-propeller core diffused faster on the PM and exhibited reduced binding to SNAP25, suggesting that these mutants shift the equilibrium between tomosyn-syntaxin-SNAP25 complexes on the PM to tomosyn-syntaxin complexes. As these deletion mutants impose less inhibition on exocytosis, we suggest that tomosyn inhibition is mediated via tomosyn-syntaxin-SNAP25 complexes and not tomosyn-syntaxin complexes. These findings characterize, for the first time, tomosyn's dynamics at the PM and its relation to its inhibition of exocytosis.
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Affiliation(s)
- Noa Bielopolski
- From the Department of Neurobiology, Life Sciences Faculty, and
| | - Alice D Lam
- the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Dana Bar-On
- From the Department of Neurobiology, Life Sciences Faculty, and Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Markus Sauer
- the Department of Biotechnology and Biophysics, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Edward L Stuenkel
- the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Uri Ashery
- From the Department of Neurobiology, Life Sciences Faculty, and Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel,
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18
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Leitman J, Barak B, Benyair R, Shenkman M, Ashery U, Hartl FU, Lederkremer GZ. ER stress-induced eIF2-alpha phosphorylation underlies sensitivity of striatal neurons to pathogenic huntingtin. PLoS One 2014; 9:e90803. [PMID: 24594939 PMCID: PMC3940916 DOI: 10.1371/journal.pone.0090803] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 02/04/2014] [Indexed: 11/18/2022] Open
Abstract
A hallmark of Huntington's disease is the pronounced sensitivity of striatal neurons to polyglutamine-expanded huntingtin expression. Here we show that cultured striatal cells and murine brain striatum have remarkably low levels of phosphorylation of translation initiation factor eIF2α, a stress-induced process that interferes with general protein synthesis and also induces differential translation of pro-apoptotic factors. EIF2α phosphorylation was elevated in a striatal cell line stably expressing pathogenic huntingtin, as well as in brain sections of Huntington's disease model mice. Pathogenic huntingtin caused endoplasmic reticulum (ER) stress and increased eIF2α phosphorylation by increasing the activity of PKR-like ER-localized eIF2α kinase (PERK). Importantly, striatal neurons exhibited special sensitivity to ER stress-inducing agents, which was potentiated by pathogenic huntingtin. We could strongly reduce huntingtin toxicity by inhibiting PERK. Therefore, alteration of protein homeostasis and eIF2α phosphorylation status by pathogenic huntingtin appears to be an important cause of striatal cell death. A dephosphorylated state of eIF2α has been linked to cognition, which suggests that the effect of pathogenic huntingtin might also be a source of the early cognitive impairment seen in patients.
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Affiliation(s)
- Julia Leitman
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Boaz Barak
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Neurobiology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ron Benyair
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Marina Shenkman
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- Department of Neurobiology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - F. Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Gerardo Z. Lederkremer
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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19
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Giladi M, Michaeli L, Almagor L, Bar-On D, Buki T, Ashery U, Khananshvili D, Hirsch JA. The C2B domain is the primary Ca2+ sensor in DOC2B: a structural and functional analysis. J Mol Biol 2013; 425:4629-41. [PMID: 23994332 DOI: 10.1016/j.jmb.2013.08.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/12/2013] [Accepted: 08/21/2013] [Indexed: 12/21/2022]
Abstract
DOC2B (double-C2 domain) protein is thought to be a high-affinity Ca(2+) sensor for spontaneous and asynchronous neurotransmitter release. To elucidate the molecular features underlying its physiological role, we determined the crystal structures of its isolated C2A and C2B domains and examined their Ca(2+)-binding properties. We further characterized the solution structure of the tandem domains (C2AB) using small-angle X-ray scattering. In parallel, we tested structure-function correlates with live cell imaging tools. We found that, despite striking structural similarity, C2B binds Ca(2+) with considerably higher affinity than C2A. The C2AB solution structure is best modeled as two domains with a highly flexible orientation and no difference in the presence or absence of Ca(2+). In addition, kinetic studies of C2AB demonstrate that, in the presence of unilamellar vesicles, Ca(2+) binding is stabilized, as reflected by the ~10-fold slower rate of Ca(2+) dissociation than in the absence of vesicles. In cells, isolated C2B translocates to the plasma membrane (PM) with an EC50 of 400 nM while the C2A does not translocate at submicromolar Ca(2+) concentrations, supporting the biochemical observations. Nevertheless, C2AB translocates to the PM with an ~2-fold lower EC50 and to a greater extent than C2B. Our results, together with previous studies, reveal that the C2B is the primary Ca(2+) sensing unit in DOC2B, whereas C2A enhances the interaction of C2AB with the PM.
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Affiliation(s)
- Moshe Giladi
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv 69978, Israel
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20
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Abstract
Alterations in the levels of synaptic proteins affect synaptic transmission and synaptic plasticity. However, the precise effects on neuronal network activity are still enigmatic. Here, we utilized microelectrode array (MEA) to elucidate how manipulation of the presynaptic release process affects the activity of neuronal networks. By combining pharmacological tools and genetic manipulation of synaptic proteins, we show that overexpression of DOC2B and Munc13-1, proteins known to promote vesicular maturation and release, elicits opposite effects on the activity of the neuronal network. Although both cause an increase in the overall number of spikes, the distribution of spikes is different. While DOC2B enhances, Munc13-1 reduces the firing rate within bursts of spikes throughout the network; however, Munc13-1 increases the rate of network bursts. DOC2B's effects were mimicked by Strontium that elevates asynchronous release but not by a DOC2B mutant that enhances spontaneous release rate. This suggests for the first time that increased asynchronous release on the single-neuron level promotes bursting activity in the network level. This innovative study demonstrates the complementary role of the network level in explaining the physiological relevance of the cellular activity of presynaptic proteins and the transformation of synaptic release manipulation from the neuron to the network level.
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Affiliation(s)
- Ayal Lavi
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Anton Sheinin
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronit Shapira
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Daniel Zelmanoff
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Uri Ashery
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
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21
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Abstract
Ras proteins undergo an incompletely understood trafficking process in the cell. Rasosomes are protein nanoparticles of 80–100 nm diameter that carry lipidated Ras isoforms (H-Ras and N-Ras) as well as their effectors through the cytoplasm and near the plasma membrane (PM). In this study, we identified the subcellular origin of rasosomes and how they spread Ras proteins through the cell. We found no dependency of rasosome formation on galectins, or on the GDP-/GTP-bound state of Ras. We found that significantly more rasosomes are associated with forms of Ras that are localized to the Golgi, namely N-Ras or the singly palmitoylated H-Ras mutant (C181S). To explore the possibility that rasosome originate from the Golgi, we used photoactivatable (PA)-GFP-H-Ras mutants and showed that rasosomes bud from the Golgi in a two-step mechanism. Newly released rasosomes first move in an energy-dependent directed fashion and then convert to randomly diffusing rasosomes. Dual fluorescence time-lapse imaging revealed the appearance of dually labeled rasosomes, indicating a dynamic exchange of cytoplasmic and PM-associated Ras with rasosome-associated Ras. Finally, higher levels of rasosomes correlate with higher levels of ERK phosphorylation, a key marker of Ras downstream signaling. We suggest that H-Ras and N-Ras proteins exchange with rasosomes that can function as carriers of palmitoylated Ras and its signals.
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Affiliation(s)
- A Grunwald
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Israel
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22
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Sauer M, van de Linde S, Holm T, Aufmkolk S, Ehmann N, Blum R, Bar-On D, Alon A, Ashery U, Ljaschenko D, Heckmann M, Kittel R. dSTORM of Synaptic Proteins. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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23
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Friedrich R, Gottfried I, Ashery U. Munc13-1 Translocates to the Plasma Membrane in a Doc2B- and Calcium-Dependent Manner. Front Endocrinol (Lausanne) 2013; 4:119. [PMID: 24062723 PMCID: PMC3775473 DOI: 10.3389/fendo.2013.00119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 08/27/2013] [Indexed: 11/13/2022] Open
Abstract
Munc13-1 is a presynaptic protein activated by calcium, calmodulin, and diacylglycerols (DAG) that is known to enhance vesicle priming. Doc2B is another presynaptic protein that translocates to the plasma membrane (PM) upon elevation of internal calcium concentration ([Ca(2+)]i) to the submicromolar range, and increases both spontaneous and asynchronous release in a calcium-dependent manner. We speculated that Doc2B also recruits Munc13-1 to the PM since these two proteins have been shown to interact physiologically and this interaction is enhanced by Ca(2+). However, this calcium-dependent co-translocation has never actually been shown. To examine this possibility, we expressed both proteins tagged to fluorescent proteins in PC12 cells and stimulated the cells to investigate the recruitment hypothesis using imaging techniques. We found that Munc13-1 does indeed translocate to the PM upon elevation in [Ca(2+)]i, but only when co-expressed with Doc2B. Interestingly, Munc13-1 co-translocates at a slower rate than Doc2B. Moreover, while Doc2B dislocates from the PM as soon as the [Ca(2+)]i returns to basal levels, Munc13-1 dislocates at a slower rate and a fraction of it accumulates on the PM. This accumulation is more pronounced under subsequent stimulations, suggesting that Munc13-1 accumulation builds up as some other factors accumulate at the PM. Munc13-1 co-translocation and accumulation was reduced when its mutant Munc13-1(H567K), which is unable to bind DAG, was co-expressed with Doc2B, suggesting that Munc13-1 accumulation depends on DAG levels. These results suggest that Doc2B enables recruitment of Munc13-1 to the PM in a [Ca(2+)]i-dependent manner and offers another possible Munc13-1-regulatory mechanism that is both calcium- and Doc2B-dependent.
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Affiliation(s)
- Reut Friedrich
- Department of Neurobiology, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Irit Gottfried
- Department of Neurobiology, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- Department of Neurobiology, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- *Correspondence: Uri Ashery, Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel e-mail:
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24
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Kwiat M, Elnathan R, Pevzner A, Peretz A, Barak B, Peretz H, Ducobni T, Stein D, Mittelman L, Ashery U, Patolsky F. Highly ordered large-scale neuronal networks of individual cells - toward single cell to 3D nanowire intracellular interfaces. ACS Appl Mater Interfaces 2012; 4:3542-9. [PMID: 22724437 DOI: 10.1021/am300602e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The use of artificial, prepatterned neuronal networks in vitro is a promising approach for studying the development and dynamics of small neural systems in order to understand the basic functionality of neurons and later on of the brain. The present work presents a high fidelity and robust procedure for controlling neuronal growth on substrates such as silicon wafers and glass, enabling us to obtain mature and durable neural networks of individual cells at designed geometries. It offers several advantages compared to other related techniques that have been reported in recent years mainly because of its high yield and reproducibility. The procedure is based on surface chemistry that allows the formation of functional, tailormade neural architectures with a micrometer high-resolution partition, that has the ability to promote or repel cells attachment. The main achievements of this work are deemed to be the creation of a large scale neuronal network at low density down to individual cells, that develop intact typical neurites and synapses without any glia-supportive cells straight from the plating stage and with a relatively long term survival rate, up to 4 weeks. An important application of this method is its use on 3D nanopillars and 3D nanowire-device arrays, enabling not only the cell bodies, but also their neurites to be positioned directly on electrical devices and grow with registration to the recording elements underneath.
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Affiliation(s)
- Moria Kwiat
- School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, ‡Department of Physiology, Sackler Medical School, and §Department of Neurobiology, The George S. Wise Faculty of Life Sciences, School of Neuroscience, Tel Aviv University , Tel Aviv 69978, Israel
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25
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Bar-On D, Wolter S, van de Linde S, Heilemann M, Nudelman G, Nachliel E, Gutman M, Sauer M, Ashery U. Super-resolution imaging reveals the internal architecture of nano-sized syntaxin clusters. J Biol Chem 2012; 287:27158-67. [PMID: 22700970 DOI: 10.1074/jbc.m112.353250] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Key synaptic proteins from the soluble SNARE (N-ethylmaleimide-sensitive factor attachment protein receptor) family, among many others, are organized at the plasma membrane of cells as clusters containing dozens to hundreds of protein copies. However, the exact membranal distribution of proteins into clusters or as single molecules, the organization of molecules inside the clusters, and the clustering mechanisms are unclear due to limitations of the imaging and analytical tools. Focusing on syntaxin 1 and SNAP-25, we implemented direct stochastic optical reconstruction microscopy together with quantitative clustering algorithms to demonstrate a novel approach to explore the distribution of clustered and nonclustered molecules at the membrane of PC12 cells with single-molecule precision. Direct stochastic optical reconstruction microscopy images reveal, for the first time, solitary syntaxin/SNAP-25 molecules and small clusters as well as larger clusters. The nonclustered syntaxin or SNAP-25 molecules are mostly concentrated in areas adjacent to their own clusters. In the clusters, the density of the molecules gradually decreases from the dense cluster core to the periphery. We further detected large clusters that contain several density gradients. This suggests that some of the clusters are formed by unification of several clusters that preserve their original organization or reorganize into a single unit. Although syntaxin and SNAP-25 share some common distributional features, their clusters differ markedly from each other. SNAP-25 clusters are significantly larger, more elliptical, and less dense. Finally, this study establishes methodological tools for the analysis of single-molecule-based super-resolution imaging data and paves the way for revealing new levels of membranal protein organization.
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Affiliation(s)
- Dana Bar-On
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, Tel Aviv University, Tel Aviv 69978, Israel
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26
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Weihberger O, Lavi A, Okujeni S, Ashery U, Egert U. State-dependent modulation of stimulus-response relations in cortical networks in vitro. BMC Neurosci 2011. [PMCID: PMC3240185 DOI: 10.1186/1471-2202-12-s1-o6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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27
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Abstract
The Sec1/munc18 protein family is essential for vesicle fusion in eukaryotic cells via binding to SNARE proteins. Protein kinase C modulates these interactions by phosphorylating munc18a thereby reducing its affinity to one of the central SNARE members, syntaxin-1a. The established hypothesis is that the reduced affinity of the phosphorylated munc18a to syntaxin-1a is a result of local electrostatic repulsion between the two proteins, which interferes with their compatibility. The current study challenges this paradigm and offers a novel mechanistic explanation by revealing a syntaxin-non-binding conformation of munc18a that is induced by the phosphomimetic mutations. In the present study, using molecular dynamics simulations, we explored the dynamics of the wild-type munc18a versus phosphomimetic mutant munc18a. We focused on the structural changes that occur in the cavity between domains 3a and 1, which serves as the main syntaxin-binding site. The results of the simulations suggest that the free wild-type munc18a exhibits a dynamic equilibrium between several conformations differing in the size of its cavity (the main syntaxin-binding site). The flexibility of the cavity's size might facilitate the binding or unbinding of syntaxin. In silico insertion of phosphomimetic mutations into the munc18a structure induces the formation of a conformation where the syntaxin-binding area is rigid and blocked as a result of interactions between residues located on both sides of the cavity. Therefore, we suggest that the reduced affinity of the phosphomimetic mutant/phosphorylated munc18a is a result of the closed-cavity conformation, which makes syntaxin binding energetically and sterically unfavorable. The current study demonstrates the potential of phosphoryalation, an essential biological process, to serve as a driving force for dramatic conformational changes of proteins modulating their affinity to target proteins. Protein phosphorylation plays a significant regulatory role in multi-component systems engaged in signal transduction or coordination of cellular processes, by activating or deactivating proteins. The potential of phosphorylation to induce substantial conformational changes in proteins, thereby changing their affinity to target proteins, has already been shown but the dynamics of the process is not fully elucidated. In the present study, we investigated, by molecular dynamics simulations, the dynamic conformational changes in munc18a, a protein that is crucial for neurotransmitter release and interacts tightly with the SNARE syntaxin-1. We further investigated the conformational changes that occur in munc18a when it is phosphorylated, reducing its affinity to syntaxin-1a. The results of the simulations suggest that there is a conformational flexibility of the syntaxin-unbounded munc18a that allows changes in the shape of the syntaxin-1a binding cavity. In silico insertion of phosphomimetic mutations into munc18a led to a reduction in the flexibility and closure of the syntaxin-binding site. We suggest that the reduced affinity of phosphorylated munc18a to syntaxin-1a stems from the difficulty of syntaxin-1a to bind to the munc18a closed-cavity conformation, induced by the PKC phosphorylation of munc18a.
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Affiliation(s)
- Dana Bar-On
- Department of Neurobiology, Tel Aviv University, Tel Aviv, Israel
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Esther Nachliel
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Menachem Gutman
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- Department of Neurobiology, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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28
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Williams AL, Bielopolski N, Meroz D, Lam AD, Passmore DR, Ben-Tal N, Ernst SA, Ashery U, Stuenkel EL. Structural and functional analysis of tomosyn identifies domains important in exocytotic regulation. J Biol Chem 2011; 286:14542-53. [PMID: 21330375 DOI: 10.1074/jbc.m110.215624] [Citation(s) in RCA: 36] [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: 11/06/2022] Open
Abstract
Tomosyn is a 130-kDa cytosolic R-SNARE protein that associates with Q-SNAREs and reduces exocytotic activity. Two paralogous genes, tomosyn-1 and -2, occur in mammals and produce seven different isoforms via alternative splicing. Here, we map the structural differences between the yeast homologue of m-tomosyn-1, Sro7, and tomosyn genes/isoforms to identify domains critical to the regulation of exocytotic activity to tomosyn that are outside the soluble N-ethylmaleimide-sensitive attachment receptor motif. Homology modeling of m-tomosyn-1 based on the known structure of yeast Sro7 revealed a highly conserved functional conformation but with tomosyn containing three additional loop domains that emanate from a β-propeller core. Notably, deletion of loops 1 and 3 eliminates tomosyn inhibitory activity on secretion without altering its soluble N-ethylmaleimide-sensitive attachment receptor pairing with syntaxin1A. By comparison, deletion of loop 2, which contains the hypervariable splice region, did not reduce the ability of tomosyn to inhibit regulated secretion. However, exon variation within the hypervariable splice region resulted in significant differences in protein accumulation of tomosyn-2 isoforms. Functional analysis of s-tomosyn-1, m-tomosyn-1, m-tomosyn-2, and xb-tomosyn-2 demonstrated that they exert similar inhibitory effects on elevated K(+)-induced secretion in PC12 cells, although m-tomosyn-2 was novel in strongly augmenting basal secretion. Finally, we report that m-tomosyn-1 is a target substrate for SUMO 2/3 conjugation and that mutation of this small ubiquitin-related modifier target site (Lys-730) enhances m-tomosyn-1 inhibition of secretion without altering interaction with syntaxin1A. Together these results suggest that multiple domains outside the R-SNARE of tomosyn are critical to the efficacy of inhibition by tomosyn on exocytotic secretion.
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Affiliation(s)
- Antionette L Williams
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
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29
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Barak B, Williams A, Bielopolski N, Gottfried I, Okun E, Brown MA, Matti U, Rettig J, Stuenkel EL, Ashery U. Tomosyn expression pattern in the mouse hippocampus suggests both presynaptic and postsynaptic functions. Front Neuroanat 2010; 4:149. [PMID: 21191478 PMCID: PMC3010824 DOI: 10.3389/fnana.2010.00149] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [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: 09/16/2010] [Accepted: 11/30/2010] [Indexed: 11/30/2022] Open
Abstract
The protein tomosyn decreases synaptic transmission and release probability of vesicles, and is essential for modulating synaptic transmission in neurons. In this study, we provide a detailed description of the expression and localization patterns of tomosyn1 and tomosyn2 in the subareas of the mouse hippocampus. Using confocal and two-photon high-resolution microscopy we demonstrate that tomosyn colocalizes with several pre- and postsynaptic markers and is found mainly in glutamatergic synapses. Specifically, we show that tomosyn1 is differentially distributed in the mouse hippocampus and concentrated mainly in the hilus and mossy fibers. Surprisingly, we found that tomosyn2 is expressed in the subiculum, CA1 and CA2 pyramidal cell bodies, dendrites and spines, and colocalizes with PSD95, suggesting a postsynaptic role. These results suggest that in addition to the well-characterized presynaptic function of tomosyn in neurotransmitter release, tomosyn2 might have a postsynaptic function, and place tomosyn as a more general regulator of synaptic transmission and plasticity.
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Affiliation(s)
- Boaz Barak
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University Tel Aviv, Israel
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30
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Friedrich R, Ashery U. From spike to graph--a complete automated single-spike analysis. J Neurosci Methods 2010; 193:271-80. [PMID: 20869399 DOI: 10.1016/j.jneumeth.2010.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 09/06/2010] [Accepted: 09/13/2010] [Indexed: 11/16/2022]
Abstract
Amperometry is a commonly used technique for detecting the kinetics of single-vesicle exocytosis with excellent temporal and spatial resolution. However, different methods of analyzing the amperometric signals can produce conflicting conclusions. We developed an efficient automated method for kinetics analysis of single spikes that does not filter the data and therefore prevents distortion of the results. The algorithm assesses the signal-to-noise ratios (SNRs) and accordingly, separates the signals using an adjustable two-threshold calculation. This enables comparing data with different SNRs from different setups. The software also includes a complete statistical analysis, with an automated selection of the most appropriate statistical tests and a graphical representation. The algorithms can be used for any other experimental results requiring the separation of signals from noise, making this method useful for many applications.
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Affiliation(s)
- Reut Friedrich
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel.
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31
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Okun E, Griffioen K, Barak B, Roberts NJ, Castro K, Pita MA, Cheng A, Mughal MR, Wan R, Ashery U, Mattson MP. Toll-like receptor 3 inhibits memory retention and constrains adult hippocampal neurogenesis. Proc Natl Acad Sci U S A 2010; 107:15625-30. [PMID: 20713712 PMCID: PMC2932590 DOI: 10.1073/pnas.1005807107] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Toll-like receptors (TLRs) are innate immune receptors that have recently emerged as regulators of neuronal survival and developmental neuroplasticity. Adult TLR3-deficient mice exhibited enhanced hippocampus-dependent working memory in the Morris water maze, novel object recognition, and contextual fear-conditioning tasks. In contrast, TLR3-deficient mice demonstrated impaired amygdala-related behavior and anxiety in the cued fear-conditioning, open field, and elevated plus maze tasks. Further, TLR3-deficient mice exhibited increased hippocampal CA1 and dentate gyrus volumes, increased hippocampal neurogenesis, and elevated levels of the AMPA receptor subunit GluR1 in the CA1 region of the hippocampus. In addition, levels of activated forms of the kinase ERK and the transcription factor CREB were elevated in the hippocampus of TLR3-deficient mice, suggesting that constitutive TLR3 signaling negatively regulates pathways known to play important roles in hippocampal plasticity. Direct activation of TLR3 by intracerebroventricular infusion of a TLR3 ligand impaired working memory, but not reference memory. Our findings reveal previously undescribed roles for TLR3 as a suppressor of hippocampal cellular plasticity and memory retention.
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Affiliation(s)
- Eitan Okun
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Kathleen Griffioen
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Boaz Barak
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Nicholas J. Roberts
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Kamilah Castro
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Mario A. Pita
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Aiwu Cheng
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Mohamed R. Mughal
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Ruiqian Wan
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Uri Ashery
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Mark P. Mattson
- Laboratory of Neurosciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
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32
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Feinshreiber L, Singer-Lahat D, Friedrich R, Matti U, Sheinin A, Yizhar O, Nachman R, Chikvashvili D, Rettig J, Ashery U, Lotan I. Non-conducting function of the Kv2.1 channel enables it to recruit vesicles for release in neuroendocrine and nerve cells. J Cell Sci 2010; 123:1940-7. [DOI: 10.1242/jcs.063719] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Regulation of exocytosis by voltage-gated K+ channels has classically been viewed as inhibition mediated by K+ fluxes. We recently identified a new role for Kv2.1 in facilitating vesicle release from neuroendocrine cells, which is independent of K+ flux. Here, we show that Kv2.1-induced facilitation of release is not restricted to neuroendocrine cells, but also occurs in the somatic-vesicle release from dorsal-root-ganglion neurons and is mediated by direct association of Kv2.1 with syntaxin. We further show in adrenal chromaffin cells that facilitation induced by both wild-type and non-conducting mutant Kv2.1 channels in response to long stimulation persists during successive stimulation, and can be attributed to an increased number of exocytotic events and not to changes in single-spike kinetics. Moreover, rigorous analysis of the pools of released vesicles reveals that Kv2.1 enhances the rate of vesicle recruitment during stimulation with high Ca2+, without affecting the size of the readily releasable vesicle pool. These findings place a voltage-gated K+ channel among the syntaxin-binding proteins that directly regulate pre-fusion steps in exocytosis.
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Affiliation(s)
- Lori Feinshreiber
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Dafna Singer-Lahat
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Reut Friedrich
- Department of Neurobiochemistry, Life Science Institute, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ulf Matti
- Physiologisches Institut, Universität des Saarlandes, 66421 Homburg/Saar, Germany
| | - Anton Sheinin
- Department of Neurobiochemistry, Life Science Institute, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ofer Yizhar
- Department of Neurobiochemistry, Life Science Institute, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Rachel Nachman
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Dodo Chikvashvili
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Jens Rettig
- Physiologisches Institut, Universität des Saarlandes, 66421 Homburg/Saar, Germany
| | - Uri Ashery
- Department of Neurobiochemistry, Life Science Institute, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ilana Lotan
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
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33
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Valensi-Kurtz M, Lefler S, Cohen MA, Aharonowiz M, Cohen-Kupiec R, Sheinin A, Ashery U, Reubinoff B, Weil M. Enriched population of PNS neurons derived from human embryonic stem cells as a platform for studying peripheral neuropathies. PLoS One 2010; 5:e9290. [PMID: 20174633 PMCID: PMC2823780 DOI: 10.1371/journal.pone.0009290] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 01/20/2010] [Indexed: 01/26/2023] Open
Abstract
Background The absence of a suitable cellular model is a major obstacle for the study of peripheral neuropathies. Human embryonic stem cells hold the potential to be differentiated into peripheral neurons which makes them a suitable candidate for this purpose. However, so far the potential of hESC to differentiate into derivatives of the peripheral nervous system (PNS) was not investigated enough and in particular, the few trials conducted resulted in low yields of PNS neurons. Here we describe a novel hESC differentiation method to produce enriched populations of PNS mature neurons. By plating 8 weeks hESC derived neural progenitors (hESC-NPs) on laminin for two weeks in a defined medium, we demonstrate that over 70% of the resulting neurons express PNS markers and 30% of these cells are sensory neurons. Methods/Findings Our method shows that the hNPs express neuronal crest lineage markers in a temporal manner, and by plating 8 weeks hESC-NPs into laminin coated dishes these hNPs were promoted to differentiate and give rise to homogeneous PNS neuronal populations, expressing several PNS lineage-specific markers. Importantly, these cultures produced functional neurons with electrophysiological activities typical of mature neurons. Moreover, supporting this physiological capacity implantation of 8 weeks old hESC-NPs into the neural tube of chick embryos also produced human neurons expressing specific PNS markers in vivo in just a few days. Having the enriched PNS differentiation system in hand, we show for the first time in human PNS neurons the expression of IKAP/hELP1 protein, where a splicing mutation on the gene encoding this protein causes the peripheral neuropathy Familial Dysautonomia. Conclusions/Significance We conclude that this differentiation system to produce high numbers of human PNS neurons will be useful for studying PNS related neuropathies and for developing future drug screening applications for these diseases.
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Affiliation(s)
- Moran Valensi-Kurtz
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Sharon Lefler
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Malkiel A. Cohen
- Department of Neurobiology, Tel Aviv University, Tel Aviv, Israel
| | | | - Rachel Cohen-Kupiec
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel
| | - Anton Sheinin
- Department of Gynecology, Hadassah University Hospital, Jerusalem, Israel
| | - Uri Ashery
- Department of Gynecology, Hadassah University Hospital, Jerusalem, Israel
| | | | - Miguel Weil
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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34
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Abstract
Ca(+2)-dependent exocytosis involves vesicle docking, priming, fusion, and recycling. This process is performed and regulated by a vast number of synaptic proteins and depends on proper protein-protein and protein-lipid interactions. Double C2 domain (DOC2) is a protein family of three isoforms found while screening DNA libraries with a C2 probe. DOC2 has three domains: the Munc13-interacting domain and tandem C2s (designated C2A and C2B) connected by a short polar linker. The C2 domain binds phospholipids in a Ca(2+)-dependent manner. This review focuses on the ubiquitously expressed isoform DOC2B. Sequence alignment of the tandem C2 protein family in mouse revealed high homology (81%) between rabphilin-3A and DOC2B proteins. We created a structural model of DOC2B's C2A based on the crystal structure of rabphilin-3A with and without calcium and found that the calcium-binding loops of DOC2B move upon calcium binding, enabling efficient plasma membrane penetration of its C2A. Here, we discuss the potential relation between the DOC2B bioinformatical model and its function and suggest a possible working model for its interaction with other proteins of the exocytotic machinery, including Munc13, Munc18, and syntaxin.
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Affiliation(s)
- Reut Friedrich
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
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35
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Kofer-Geles M, Gottfried I, Haklai R, Elad-Zefadia G, Kloog Y, Ashery U. Rasosomes spread Ras signals from plasma membrane 'hotspots'. Biochim Biophys Acta 2009; 1793:1691-702. [PMID: 19695294 DOI: 10.1016/j.bbamcr.2009.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 07/28/2009] [Accepted: 08/10/2009] [Indexed: 12/31/2022]
Abstract
Ras proteins regulate cell growth, differentiation, and apoptosis from various cellular platforms. We have recently identified a novel potential signaling platform, the rasosome, which moves rapidly near the plasma membrane (PM) and in the cytosol, carrying multiple copies of palmitoylated Ras proteins. In the present study we demonstrate that rasosomes are unique entities distinct from PM nanoclusters or from endocytotic compartments. In addition, we examine whether rasosomes can act as regulated Ras signaling platforms. We show that a single rasosome simultaneously carries different types of Ras molecules in their active and inactive state, suggesting that rasosomes can upload and download Ras signals. Total internal reflection fluorescence (TIRF) microscopy combined with fast time-lapse and a new spatial analysis algorithm demonstrate that rasosome movement near the PM is restricted to distinctive areas, rasosomal 'hotspots', localized between actin filament cages. In addition, Ras-binding domain of Raf-1 (RBD) is recruited to Ras in rasosomal hotspots as revealed by bimolecular fluorescence complementation experiments. Interestingly, epidermal growth factor stimulates H/NRas activation on rasosomes and the subsequent recruitment of RBD to rasosomes. Moreover, we show that rasosomes are loaded with Ras downstream effectors and modulators. These findings establish that physiological stimulation originating from PM hotspots is transduced to rasosomes, which appear to serve as robust Ras signaling platforms that spread signals across the cell.
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Affiliation(s)
- Merav Kofer-Geles
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
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36
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Gottfried I, Ehrlich M, Ashery U. HIP1 exhibits an early recruitment and a late stage function in the maturation of coated pits. Cell Mol Life Sci 2009; 66:2897-911. [PMID: 19626275 DOI: 10.1007/s00018-009-0077-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [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: 06/03/2009] [Accepted: 06/12/2009] [Indexed: 11/26/2022]
Abstract
Huntingtin interacting protein 1 (HIP1) is an accessory protein of the clathrin-mediated endocytosis (CME) pathway, yet its precise role and the step at which it becomes involved are unclear. We employed live-cell imaging techniques to focus on the early steps of CME and characterize HIP1 dynamics. We show that HIP1 is highly colocalized with clathrin at the plasma membrane and shares similar dynamics with a subpopulation of clathrin assemblies. Employing transferrin receptor fused to pHluorin, we distinguished between open pits to which HIP1 localizes and newly internalized vesicles that are devoid of HIP1. Moreover, shRNA knockdown of clathrin compromised HIP1 membranal localization, unlike the reported behavior of Sla2p. HIP1 fragment, lacking its ANTH and Talin-like domains, inhibits internalization of transferrin, but retains colocalization with membranal clathrin assemblies. These data demonstrate HIP1's role in pits maturation and formation of the coated vesicle, and its strong dependence on clathrin for membranal localization.
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Affiliation(s)
- Irit Gottfried
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel
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37
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Ashery U, Bielopolski N, Barak B, Yizhar O. Friends and foes in synaptic transmission: the role of tomosyn in vesicle priming. Trends Neurosci 2009; 32:275-82. [PMID: 19307030 PMCID: PMC2713869 DOI: 10.1016/j.tins.2009.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 01/06/2009] [Accepted: 01/07/2009] [Indexed: 12/24/2022]
Abstract
Priming is the process by which vesicles become available for fusion at nerve terminals and is modulated by numerous proteins and second messengers. One of the prominent members of this diverse family is tomosyn. Tomosyn has been identified as a syntaxin-binding protein; it inhibits vesicle priming, but its mode of action is not fully understood. The inhibitory activity of tomosyn depends on its N-terminal WD40-repeat domain and is regulated by the binding of its SNARE motif to syntaxin. Here, we describe new physiological information on the function of tomosyn and address possible interpretations of these results in the framework of the recently described crystal structure of the yeast tomosyn homolog Sro7. We also present possible molecular scenarios for vesicle priming and the involvement of tomosyn in these processes.
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Affiliation(s)
- Uri Ashery
- Department of Neurobiology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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38
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Abstract
Voltage-gated ion channels are well characterized for their function in excitability signals. Accumulating studies, however, have established an ion-independent function for the major classes of ion channels in cellular signaling. During the last few years we established a novel role for Kv2.1, a voltage-gated potassium (Kv) channel, classically known for its role of repolarizing the membrane potential, in facilitation of exocytosis. Kv2.1 induces facilitation of depolarization-induced release through its direct interaction with syntaxin, a protein component of the exocytotic machinery, independently of the potassium ion flow through the channel's pore. Here, we review our recent studies, further characterize the phenomena (using chromaffin cells and carbon fiber amperometry), and suggest plausible mechanisms that can underlie this facilitation of release.
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Affiliation(s)
- Lori Feinshreiber
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel
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39
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Abstract
In Alzheimer's disease (AD), neurons suffer dysfunction and death associated with aberrant tau phosphorylation and subsequent neurofibrillary tangles. A new study reveals a surprising neuroprotective role for a truncated p73 isoform (DeltaNp73). Aged mice with reduced DeltaNp73 levels exhibit tau pathology and cognitive deficits, and DeltaNp73 reduction in mice with amyloid pathology causes extensive tangle formation and neuron death. These findings provide a novel animal model of AD and a potential therapeutic role for DeltaNp73 inducers.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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40
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Bar-On D, Winter U, Nachliel E, Gutman M, Fasshauer D, Lang T, Ashery U. Erratum “Imaging the assembly and disassembly kinetics of cis-SNARE complexes on native plasma membranes” [FEBS Lett. 582 (2008) 3563-3568]. FEBS Lett 2008. [DOI: 10.1016/j.febslet.2008.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Yizhar O, Ashery U. Modulating vesicle priming reveals that vesicle immobilization is necessary but not sufficient for fusion-competence. PLoS One 2008; 3:e2694. [PMID: 18628949 PMCID: PMC2444019 DOI: 10.1371/journal.pone.0002694] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 05/29/2008] [Indexed: 11/19/2022] Open
Abstract
In neurons and neuroendocrine cells, docked vesicles need to undergo priming to become fusion competent. Priming is a multi-step process that was shown to be associated with vesicle immobilization. However, it is not known whether vesicle immobilization is sufficient to acquire complete fusion competence. To extend our understanding of the physical manifestation of vesicle priming, we took advantage of tomosyn, a SNARE-related protein that specifically inhibits vesicle priming, and measured its effect on vesicle dynamics in live chromaffin cells using total internal reflection fluorescence microscopy. We show here that while in control cells vesicles undergo immobilization before fusion, vesicle immobilization is attenuated in tomosyn overexpressing cells. This in turn increases the turnover rate of vesicles near the membrane and attenuates the fusion of newcomer vesicles. Moreover, the release probability of immobile vesicles in tomosyn cells is significantly reduced, suggesting that immobilization is an early and necessary step in priming but is insufficient, as further molecular processes are needed to acquire complete fusion competence. Using tomosyn as a molecular tool we provide a mechanistic link between functional docking and priming and suggest that functional docking is the first step in vesicle priming, followed by molecular modifications that do not translate into changes in vesicle mobility.
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Affiliation(s)
- Ofer Yizhar
- Department of Neurobiology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Uri Ashery
- Department of Neurobiology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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42
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Zeniou-Meyer M, Zabari N, Ashery U, Chasserot-Golaz S, Haeberlé AM, Demais V, Bailly Y, Gottfried I, Nakanishi H, Neiman AM, Du G, Frohman MA, Bader MF, Vitale N. Phospholipase D1 Production of Phosphatidic Acid at the Plasma Membrane Promotes Exocytosis of Large Dense-core Granules at a Late Stage. J Biol Chem 2007; 282:21746-57. [PMID: 17540765 DOI: 10.1074/jbc.m702968200] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Substantial efforts have recently been made to demonstrate the importance of lipids and lipid-modifying enzymes in various membrane trafficking processes, including calcium-regulated exocytosis of hormones and neurotransmitters. Among bioactive lipids, phosphatidic acid (PA) is an attractive candidate to promote membrane fusion through its ability to change membrane topology. To date, however, the biosynthetic pathway, the dynamic location, and actual function of PA in secretory cells remain unknown. Using a short interference RNA strategy on chromaffin and PC12 cells, we demonstrate here that phospholipase D1 is activated in secretagogue-stimulated cells and that it produces PA at the plasma membrane at the secretory granule docking sites. We show that phospholipase D1 activation and PA production represent key events in the exocytotic progression. Membrane capacitance measurements indicate that reduction of endogenous PA impairs the formation of fusion-competent granules. Finally, we show that the PLD1 short interference RNA-mediated inhibition of exocytosis can be rescued by exogenous provision of a lipid that favors the transition of opposed bi-layer membranes to hemifused membranes having the outer leaflets fused. Our findings demonstrate that PA synthesis is required during exocytosis to facilitate a late event in the granule fusion pathway. We propose that the underlying mechanism is related to the ability of PA to alter membrane curvature and promote hemi-fusion.
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Affiliation(s)
- Maria Zeniou-Meyer
- Département Neurotransmission & Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives, CNRS and Université Louis Pasteur, 5 rue Blaise Pascal, Strasbourg, France
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43
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Yizhar O, Lipstein N, Gladycheva SE, Matti U, Ernst SA, Rettig J, Stuenkel EL, Ashery U. Multiple functional domains are involved in tomosyn regulation of exocytosis. J Neurochem 2007; 103:604-16. [PMID: 17666050 DOI: 10.1111/j.1471-4159.2007.04791.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tomosyn is a cytoplasmic protein that was shown to bind to Syntaxin1 and SNAP-25 through an R-SNARE domain, forming a complex that is almost identical in structure to the neuronal SNARE complex. Tomosyn inhibits exocytosis in various cell types and these effects were attributed to direct competition between tomosyn's SNARE domain and Synaptobrevin/VAMP. In the present study, we investigated the contribution of different domains of tomosyn to its activity. We show that a tomosyn mutant that lacks the entire SNARE domain is a potent inhibitor of vesicle priming, similar to the full-length tomosyn. The SNARE domain of tomosyn failed to inhibit exocytosis, indicating that this domain is not required for the inhibition. In contrast, over-expression of a N-terminally truncated mutant did not lead to inhibition of exocytosis although this mutant still bound to Syntaxin. Our results indicate that tomosyn can inhibit exocytosis independently of its SNARE interaction with Syntaxin and that the integrity of the WD40-domain is crucial for tomosyn's inhibitory function. Furthermore, we demonstrate that the entire N-terminal region of tomosyn, the WD40-repeats and the linker, is required for tomosyn's inhibitory effect.
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Affiliation(s)
- Ofer Yizhar
- Department of Neurobiochemistry, Life Sciences Institute, Tel Aviv University, Tel Aviv, Israel
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44
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Gladycheva SE, Lam AD, Liu J, D'Andrea-Merrins M, Yizhar O, Lentz SI, Ashery U, Ernst SA, Stuenkel EL. Receptor-mediated regulation of tomosyn-syntaxin 1A interactions in bovine adrenal chromaffin cells. J Biol Chem 2007; 282:22887-99. [PMID: 17545156 DOI: 10.1074/jbc.m701787200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Tomosyn, a soluble R-SNARE protein identified as a binding partner of the Q-SNARE syntaxin 1A, is thought to be critical in setting the level of fusion-competent SNARE complexes for neurosecretion. To date, there has been no direct evaluation of the dynamics in which tomosyn transits through tomosyn-SNARE complexes or of the extent to which tomosyn-SNARE complexes are regulated by secretory demand. Here, we employed biochemical and optical approaches to characterize the dynamic properties of tomosyn-syntaxin 1A complexes in live adrenal chromaffin cells. We demonstrate that secretagogue stimulation results in the rapid translocation of tomosyn from the cytosol to plasma membrane regions and that this translocation is associated with an increase in the tomosyn-syntaxin 1A interaction, including increased cycling of tomosyn into tomosyn-SNARE complexes. The secretagogue-induced interaction was strongly reduced by pharmacological inhibition of the Rho-associated coiled-coil forming kinase, a result consistent with findings demonstrating secretagogue-induced activation of RhoA. Stimulation of chromaffin cells with lysophosphatidic acid, a nonsecretory stimulus that strongly activates RhoA, resulted in effects on tomosyn similar to that of application of the secretagogue. In PC-12 cells overexpressing tomosyn, secretagogue stimulation in the presence of lysophosphatidic acid resulted in reduced evoked secretory responses, an effect that was eliminated upon inhibition of Rho-associated coiled-coil forming kinase. Moreover, this effect required an intact interaction between tomosyn and syntaxin 1A. Thus, modulation of the tomosyn-syntaxin 1A interaction in response to secretagogue activation is an important mechanism allowing for dynamic regulation of the secretory response.
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Affiliation(s)
- Svetlana E Gladycheva
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
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45
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Singer-Lahat D, Sheinin A, Chikvashvili D, Tsuk S, Greitzer D, Friedrich R, Feinshreiber L, Ashery U, Benveniste M, Levitan ES, Lotan I. K+ channel facilitation of exocytosis by dynamic interaction with syntaxin. J Neurosci 2007; 27:1651-8. [PMID: 17301173 PMCID: PMC6673747 DOI: 10.1523/jneurosci.4006-06.2007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Kv channels inhibit release indirectly by hyperpolarizing membrane potential, but the significance of Kv channel interaction with the secretory apparatus is not known. The Kv2.1 channel is commonly expressed in the soma and dendrites of neurons, where it could influence the release of neuropeptides and neurotrophins, and in neuroendocrine cells, where it could influence hormone release. Here we show that Kv2.1 channels increase dense-core vesicle (DCV)-mediated release after elevation of cytoplasmic Ca2+. This facilitation occurs even after disruption of pore function and cannot be explained by changes in membrane potential and cytoplasmic Ca2+. However, triggering release increases channel binding to syntaxin, a secretory apparatus protein. Disrupting this interaction with competing peptides or by deleting the syntaxin association domain of the channel at the C terminus blocks facilitation of release. Thus, direct association of Kv2.1 with syntaxin promotes exocytosis. The dual functioning of the Kv channel to influence release, through its pore to hyperpolarize the membrane potential and through its C-terminal association with syntaxin to directly facilitate release, reinforces the requirements for repetitive firing for exocytosis of DCVs in neuroendocrine cells and in dendrites.
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Affiliation(s)
- Dafna Singer-Lahat
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Anton Sheinin
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Dodo Chikvashvili
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Sharon Tsuk
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Dafna Greitzer
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Reut Friedrich
- Department of Neurobiochemistry, Life Sciences Institute, Tel-Aviv University, 69978 Ramat-Aviv, Israel
| | - Lori Feinshreiber
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
| | - Uri Ashery
- Department of Neurobiochemistry, Life Sciences Institute, Tel-Aviv University, 69978 Ramat-Aviv, Israel
| | - Morris Benveniste
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310
| | - Edwin S. Levitan
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, and
| | - Ilana Lotan
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, and
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46
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Nili U, de Wit H, Gulyas-Kovacs A, Toonen RF, Sørensen JB, Verhage M, Ashery U. Munc18-1 phosphorylation by protein kinase C potentiates vesicle pool replenishment in bovine chromaffin cells. Neuroscience 2006; 143:487-500. [PMID: 16997485 DOI: 10.1016/j.neuroscience.2006.08.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [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: 07/03/2006] [Revised: 08/07/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
Activation of protein kinase C (PKC) after robust stimulation is necessary for vesicle pool replenishment in secretory cells. Here we studied the contribution of a prominent downstream PKC target, Munc18-1, to this process in bovine chromaffin cells. In these cells, both activation of endogenous PKC and overexpressing of Munc18-1 promote vesicle pool replenishment after an extensive stimulation. In order to study the physiological relevance of PKC-dependent Munc18-1 phosphorylation, we generated two Munc18-1 phospho-mutants; one that mimics a constitutively PKC-phosphorylated Munc18-1 (i.e. a phosphomimetic mutant; Munc18-1(S313D)) and a second that cannot be PKC-phosphorylated (Munc18-1(3A)). Overexpression of Munc18-1(3A) caused a significant decrease in vesicle pool replenishment following a depleting stimulation, while Munc18-1(S313D) caused a significant increase in vesicle pool replenishment. These findings suggested that the phosphorylation of Munc18-1 by PKC potentiates vesicle pool replenishment. This hypothesis was further strengthened by the finding that overexpression of wild type Munc18-1 in the presence of a PKC inhibitor caused a significant reduction in vesicle pool replenishment, similar to that observed with Munc18-1(3A). Moreover, overexpression of Munc18-1(S313D) in the presence of the PKC inhibitor partly alleviated this attenuation, elucidating Munc18-1's unique contribution to vesicle pool replenishment. Finally, we demonstrate that Munc18-1 promotes vesicle docking in a phosphorylation-independent manner. This is deduced from the findings that both the wild type and the two Munc18-1 phospho-mutants enhanced docking to the same extent in bovine chromaffin cells. We conclude that Munc18-1 facilitates docking in a PKC phosphorylation-independent manner, and that its phosphorylation by PKC potentiates vesicle pool replenishment following a depleting stimulation, at a post-docking stage.
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Affiliation(s)
- U Nili
- Department of Neurobiochemistry, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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47
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Abstract
Ras signaling to its downstream effectors appears to include combinations of extracellular-signal-regulated Ras activation at the plasma membrane (PM) and endomembranes, dynamic lateral segregation in the PM, and translocation of Ras from the PM to intracellular compartments. These processes are governed by the C-terminal polybasic farnesyl domain in K-Ras 4B and by the cysteine-palmitoylated C-terminal farnesyl domains in H-Ras and N-Ras. K-Ras 4B has no palmitoylated cysteines. Depalmitoylation/repalmitoylation of H-/N-Ras proteins promotes their cellular redistribution and signaling by mechanisms as yet unknown, possibly involving chaperones. Palmitoylation of H-/N-Ras also promotes their association with 'rasosomes', randomly diffusing nanoparticles that apparently provide a means by which multiple copies of activated Ras and its signal can spread rapidly. Ubiquitination of H-Ras evidently targets it to the endosomes. The polybasic farnesyl domain of K-Ras 4B was shown to act as a target for Ca++/calmodulin, which sequesters the active protein from the PM, thereby facilitating its trafficking to Golgi apparatus and early endosomes. Protein kinase C-dependent phosphorylation of S181 in K-Ras 4B was shown to provide a regulated farnesyl-electrostatic switch on K-Ras 4B, which promotes its translocation to the mitochondria. All these translocation events are characterized by nonconventional trafficking of the farnesyl-modified Ras proteins and seem to govern the selectivity and probably also the robustness of the Ras signal. In this review, we discuss the various modifications and interactions of the farnesylated C-terminus, the trafficking of Ras proteins in the PM and between the PM and the endomembranes, and the relevance of the subcellular localization of Ras for Ras function.
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Affiliation(s)
- Uri Ashery
- Department of Neurobiochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel
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48
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Ashery U, Yizhar O, Rotblat B, Elad-Sfadia G, Barkan B, Haklai R, Kloog Y. Spatiotemporal organization of Ras signaling: rasosomes and the galectin switch. Cell Mol Neurobiol 2006; 26:471-95. [PMID: 16691442 DOI: 10.1007/s10571-006-9059-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Accepted: 03/14/2006] [Indexed: 12/31/2022]
Abstract
1. Ras signaling and oncogenesis depend on the dynamic interplay of Ras with distinctive plasma membrane (PM) microdomains and various intracellular compartments. Such interaction is dictated by individual elements in the carboxy-terminal domain of the Ras proteins, including a farnesyl isoprenoid group, sequences in the hypervariable region (hvr)-linker, and palmitoyl groups in H/N-Ras isoforms. 2. The farnesyl group acts as a specific recognition unit that interacts with prenyl-binding pockets in galectin-1 (Gal-1), galectin-3 (Gal-3), and cGMP phosphodiesterase delta. This interaction appears to contribute to the prolongation of Ras signals in the PM, the determination of Ras effector usage, and perhaps also the transport of cytoplasmic Ras. Gal-1 promotes H-Ras signaling to Raf at the expense of phosphoinositide 3-kinase (PI3-K) and Ral guanine nucleotide exchange factor (RalGEF), while galectin-3 promotes K-Ras signaling to both Raf and PI3-K. 3. The hvr-linker and the palmitates of H-Ras and N-Ras determine the micro- and macro-localizations of these proteins in the PM and in the Golgi, as well as in 'rasosomes', randomly moving nanoparticles that carry palmitoylated Ras proteins and their signal through the cytoplasm.4. The dynamic compartmentalization of Ras proteins contributes to the spatial organization of Ras signaling, promotes redistribution of Ras, and provides an additional level of selectivity to the signal output of this regulatory GTPase.
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Affiliation(s)
- Uri Ashery
- Department of Neurobiochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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49
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Abstract
Spatiotemporal modulation of Ras signaling from different intracellular compartments requires mechanisms allowing Ras and its signals to navigate across cells. Here, we describe one mechanism by which clusters of palmitoylated H-Ras and N-Ras isoforms but not nonpalmitoylated K-Ras diffuse through the cytoplasm, independently of ATP, on fast, randomly moving, small cytosolic nanoparticles ("rasosomes"). Rasosomes forced to diffuse out of live cells and trapped by Ras antibody beads appear as round structures of 80- to 100-nm diameter. Association of H-Ras with rasosomes requires Ras palmitoylation and the hypervariable sequence (hvr) upstream of the palmitoylated cysteines. H-Ras hvr mutants that fail to interact with rasosomes are biologically inactive. Epidermal growth factor stimulation rapidly increases active H-Ras-GTP and phosphorylated extracellular signal-regulated kinase (ERK) on rasosomes. Similarly, rasosomes carrying H-Ras(G12V) but not H-Ras are loaded with active ERK. Thus, the rasosome represents a hitherto unknown particle that enables Ras signal information to spread rapidly across cells.
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Affiliation(s)
- Barak Rotblat
- Department of Neurobiochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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50
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Mezer A, Ashery U, Gutman M, Project E, Bosis E, Fibich G, Nachliel E. Systematic search for the rate constants that control the exocytotic process from chromaffin cells by a Genetic Algorithm. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2006; 1763:345-55. [PMID: 16630666 DOI: 10.1016/j.bbamcr.2006.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 02/09/2006] [Accepted: 02/10/2006] [Indexed: 11/30/2022]
Abstract
We have recently created a kinetic model that reproduces the dynamics of exocytosis with high accuracy. The reconstruction necessitated a search, in a multi-dimensional parameter space, for 37 parameters that described the system, with no assurance that the parameters, which reconstructed the observations, are a unique set. In the present study, a Genetic Algorithm (GA) was used for a thorough search in the unknown parameter space, using a strategy of gradual increase of the complexity of the analyzed input data. Upon systematic incorporation of one to four measurable parameters, used as input signals for the analysis, the constraint set on the GA search imposed the convergence of the free parameters into a single narrow range. The mean values for each adjustable parameter represent a minimum for the fitness function in the multi-dimensional parameter space. The GA search demonstrates that the parameters that control the kinetics of exocytosis are the rate constants of the steps downstream to synaptotagmin binding, and that the equilibrium constant of the binding of calcium to Munc13 controls the calcium-dependent priming process. Thus, the systematic use of the GA creates a link between specific reactions in the process of exocytosis and experimental phenotypes.
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Affiliation(s)
- Aviv Mezer
- Laser Laboratory for Fast Reactions in Biology, Department of Biochemistry, Tel Aviv University, Israel
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