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Chaves T, Fazekas CL, Horváth K, Correia P, Szabó A, Török B, Bánrévi K, Zelena D. Stress Adaptation and the Brainstem with Focus on Corticotropin-Releasing Hormone. Int J Mol Sci 2021; 22:ijms22169090. [PMID: 34445795 PMCID: PMC8396605 DOI: 10.3390/ijms22169090] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/18/2021] [Accepted: 08/20/2021] [Indexed: 12/13/2022] Open
Abstract
Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, including CRH, might be co-localized in the brainstem nuclei. Here we focused on CRH as its role in stress regulation is well-known and widely accepted and other CRH neurons scattered along the brain may also complement the function of the PVN. Although CRH-positive cells are present on some parts of the brainstem, sometimes even in comparable amounts as in the PVN, not much is known about their contribution to stress adaptation. Based on the role of the Barrington’s nucleus in micturition and the inferior olivary complex in the regulation of fine motoric—as the main CRH-containing brainstem areas—we might assume that these areas regulate stress-induced urination and locomotion, respectively. Further studies are necessary for the field.
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Affiliation(s)
- Tiago Chaves
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Csilla Lea Fazekas
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Krisztina Horváth
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Pedro Correia
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Adrienn Szabó
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Bibiána Török
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Janos Szentagothai School of Neurosciences, Semmelweis University, 1083 Budapest, Hungary
| | - Krisztina Bánrévi
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
| | - Dóra Zelena
- Laboratory of Behavioural and Stress Studies, Institute of Experimental Medicine, 1083 Budapest, Hungary; (T.C.); (C.L.F.); (K.H.); (P.C.); (A.S.); (B.T.); (K.B.)
- Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, 7624 Pécs, Hungary
- Correspondence:
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Göhde R, Naumann B, Laundon D, Imig C, McDonald K, Cooper BH, Varoqueaux F, Fasshauer D, Burkhardt P. Choanoflagellates and the ancestry of neurosecretory vesicles. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190759. [PMID: 33550951 PMCID: PMC7934909 DOI: 10.1098/rstb.2019.0759] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2020] [Indexed: 01/08/2023] Open
Abstract
Neurosecretory vesicles are highly specialized trafficking organelles that store neurotransmitters that are released at presynaptic nerve endings and are, therefore, important for animal cell-cell signalling. Despite considerable anatomical and functional diversity of neurons in animals, the protein composition of neurosecretory vesicles in bilaterians appears to be similar. This similarity points towards a common evolutionary origin. Moreover, many putative homologues of key neurosecretory vesicle proteins predate the origin of the first neurons, and some even the origin of the first animals. However, little is known about the molecular toolkit of these vesicles in non-bilaterian animals and their closest unicellular relatives, making inferences about the evolutionary origin of neurosecretory vesicles extremely difficult. By comparing 28 proteins of the core neurosecretory vesicle proteome in 13 different species, we demonstrate that most of the proteins are present in unicellular organisms. Surprisingly, we find that the vesicular membrane-associated soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein synaptobrevin is localized to the vesicle-rich apical and basal pole in the choanoflagellate Salpingoeca rosetta. Our 3D vesicle reconstructions reveal that the choanoflagellates S. rosetta and Monosiga brevicollis exhibit a polarized and diverse vesicular landscape reminiscent of the polarized organization of chemical synapses that secrete the content of neurosecretory vesicles into the synaptic cleft. This study sheds light on the ancestral molecular machinery of neurosecretory vesicles and provides a framework to understand the origin and evolution of secretory cells, synapses and neurons. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'.
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Affiliation(s)
- Ronja Göhde
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
| | - Benjamin Naumann
- Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Davis Laundon
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Kent McDonald
- Electron Microscope Laboratory, University of California, Berkeley, CA 94720, USA
| | - Benjamin H. Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Gottingen, Germany
| | - Frédérique Varoqueaux
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Dirk Fasshauer
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Pawel Burkhardt
- Sars International Centre for Molecular Marine Biology, University of Bergen, 5006 Bergen, Norway
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Capture of Dense Core Vesicles at Synapses by JNK-Dependent Phosphorylation of Synaptotagmin-4. Cell Rep 2018; 21:2118-2133. [PMID: 29166604 PMCID: PMC5714612 DOI: 10.1016/j.celrep.2017.10.084] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 10/05/2017] [Accepted: 10/23/2017] [Indexed: 01/04/2023] Open
Abstract
Delivery of neurotrophins and neuropeptides via long-range trafficking of dense core vesicles (DCVs) from the cell soma to nerve terminals is essential for synapse modulation and circuit function. But the mechanism by which transiting DCVs are captured at specific sites is unknown. Here, we discovered that Synaptotagmin-4 (Syt4) regulates the capture and spatial distribution of DCVs in hippocampal neurons. We found that DCVs are highly mobile and undergo long-range translocation but switch directions only at the distal ends of axons, revealing a circular trafficking pattern. Phosphorylation of serine 135 of Syt4 by JNK steers DCV trafficking by destabilizing Syt4-Kif1A interaction, leading to a transition from microtubule-dependent DCV trafficking to capture at en passant presynaptic boutons by actin. Furthermore, neuronal activity increased DCV capture via JNK-dependent phosphorylation of the S135 site of Syt4. Our data reveal a mechanism that ensures rapid, site-specific delivery of DCVs to synapses. Syt4-bearing dense core vesicles in axons traffic continually in a circular pattern Phosphorylation of S135 of Syt4 by JNK destabilizes Syt4-Kif1A binding Destabilized Syt4-Kif1A binding promotes capture of vesicles at synapses by actin Neuronal activity increases vesicle capture via S135-dependent JNK phosphorylation
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Jovanović S, Kravić-Stevović T. Ultrastructural morphometry of neurosecretory granules in the neuroblastomas of paediatric patients. MEDICINSKI PODMLADAK 2018. [DOI: 10.5937/mp69-13874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Wilkie IC. Functional Morphology of the Arm Spine Joint and Adjacent Structures of the Brittlestar Ophiocomina nigra (Echinodermata: Ophiuroidea). PLoS One 2016; 11:e0167533. [PMID: 27974856 PMCID: PMC5156572 DOI: 10.1371/journal.pone.0167533] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 11/15/2016] [Indexed: 11/18/2022] Open
Abstract
The skeletal morphology of the arm spine joint of the brittlestar Ophiocomina nigra was examined by scanning electron microscopy and the associated epidermis, connective tissue structures, juxtaligamental system and muscle by optical and transmission electron microscopy. The behaviour of spines in living animals was observed and two experiments were conducted to establish if the spine ligament is mutable collagenous tissue: these determined (1) if animals could detach spines to which plastic tags had been attached and (2) if the extension under constant load of isolated joint preparations was affected by high potassium stimulation. The articulation normally operates as a flexible joint in which the articular surfaces are separated by compliant connective tissue. The articular surfaces comprise a reniform apposition and peg-in-socket mechanical stop, and function primarily to stabilise spines in the erect position. Erect spines can be completely immobilised, which depends on the ligament having mutable tensile properties, as was inferred from the ability of animals to detach tagged spines and the responsiveness of isolated joint preparations to high potassium. The epidermis surrounding the joint has circumferential constrictions that facilitate compression folding and unfolding when the spine is inclined. The interarticular connective tissue is an acellular meshwork of collagen fibril bundles and may serve to reduce frictional forces between the articular surfaces. The ligament consists of parallel bundles of collagen fibrils and 7-14 nm microfibrils. Its passive elastic recoil contributes to the re-erection of inclined spines. The ligament is permeated by cell processes containing large dense-core vesicles, which belong to two types of juxtaligamental cells, one of which is probably peptidergic. The spine muscle consists of obliquely striated myocytes that are linked to the skeleton by extensions of their basement membranes. Muscle contraction may serve mainly to complete the process of spine erection by ensuring close contact between the articular surfaces.
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Affiliation(s)
- Iain C. Wilkie
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland, United Kingdom
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Petters C, Thiel K, Dringen R. Lysosomal iron liberation is responsible for the vulnerability of brain microglial cells to iron oxide nanoparticles: comparison with neurons and astrocytes. Nanotoxicology 2015; 10:332-42. [DOI: 10.3109/17435390.2015.1071445] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Charlotte Petters
- Center for Biomedical Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany,
- Center for Environmental Research and Sustainable Technology, Bremen, Germany, and
| | - Karsten Thiel
- Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Bremen, Germany
| | - Ralf Dringen
- Center for Biomedical Interactions Bremen, Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany,
- Center for Environmental Research and Sustainable Technology, Bremen, Germany, and
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Scharfman HE, MacLusky NJ. Differential regulation of BDNF, synaptic plasticity and sprouting in the hippocampal mossy fiber pathway of male and female rats. Neuropharmacology 2013; 76 Pt C:696-708. [PMID: 23660230 DOI: 10.1016/j.neuropharm.2013.04.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/10/2013] [Accepted: 04/15/2013] [Indexed: 10/26/2022]
Abstract
Many studies have described potent effects of BDNF, 17β-estradiol or androgen on hippocampal synapses and their plasticity. Far less information is available about the interactions between 17β-estradiol and BDNF in hippocampus, or interactions between androgen and BDNF in hippocampus. Here we review the regulation of BDNF in the mossy fiber pathway, a critical part of hippocampal circuitry. We discuss the emerging view that 17β-estradiol upregulates mossy fiber BDNF synthesis in the adult female rat, while testosterone exerts a tonic suppression of mossy fiber BDNF levels in the adult male rat. The consequences are interesting to consider: in females, increased excitability associated with high levels of BDNF in mossy fibers could improve normal functions of area CA3, such as the ability to perform pattern completion. However, memory retrieval may lead to anxiety if stressful events are recalled. Therefore, the actions of 17β-estradiol on the mossy fiber pathway in females may provide a potential explanation for the greater incidence of anxiety-related disorders and post-traumatic stress syndrome (PTSD) in women relative to men. In males, suppression of BDNF-dependent plasticity in the mossy fibers may be protective, but at the 'price' of reduced synaptic plasticity in CA3. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Helen E Scharfman
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Rd., Bldg. 35, Orangeburg, NY 10962, USA; Department of Child & Adolescent Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA; Department of Physiology & Neuroscience, New York University Langone Medical Center, New York, NY 10016, USA; Department of Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA.
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9
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Scalettar BA, Jacobs C, Fulwiler A, Prahl L, Simon A, Hilken L, Lochner JE. Hindered submicron mobility and long-term storage of presynaptic dense-core granules revealed by single-particle tracking. Dev Neurobiol 2012; 72:1181-95. [PMID: 21976424 DOI: 10.1002/dneu.20984] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 09/26/2011] [Accepted: 09/27/2011] [Indexed: 01/29/2023]
Abstract
Dense-core granules (DCGs) are organelles found in neuroendocrine cells and neurons that house, transport, and release a number of important peptides and proteins. In neurons, DCG cargo can include the secreted neuromodulatory proteins tissue plasminogen activator (tPA) and/or brain-derived neurotrophic factor (BDNF), which play a key role in modulating synaptic efficacy in the hippocampus. This function has spurred interest in DCGs that localize to synaptic contacts between hippocampal neurons, and several studies recently have established that DCGs localize to, and undergo regulated exocytosis from, postsynaptic sites. To complement this work, we have studied presynaptically localized DCGs in hippocampal neurons, which are much more poorly understood than their postsynaptic analogs. Moreover, to enhance relevance, we visualized DCGs via fluorescence labeling of exogenous and endogenous tPA and BDNF. Using single-particle tracking, we determined trajectories of more than 150 presynaptically localized DCGs. These trajectories reveal that mobility of DCGs in presynaptic boutons is highly hindered and that storage is long-lived. We also computed mean-squared displacement curves, which can be used to elucidate mechanisms of transport. Over shorter time windows, most curves are linear, demonstrating that DCG transport in boutons is driven predominantly by diffusion. The remaining curves plateau with time, consistent with motion constrained by a submicron-sized corral. These results have relevance to recent models of presynaptic organization and to recent hypotheses about DCG cargo function. The results also provide estimates for transit times to the presynaptic plasma membrane that are consistent with measured times for onset of neurotrophin release from synaptically localized DCGs.
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Affiliation(s)
- B A Scalettar
- Department of Physics, Lewis and Clark College, Portland, Oregon 97219, USA
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10
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Frooninckx L, Van Rompay L, Temmerman L, Van Sinay E, Beets I, Janssen T, Husson SJ, Schoofs L. Neuropeptide GPCRs in C. elegans. Front Endocrinol (Lausanne) 2012; 3:167. [PMID: 23267347 PMCID: PMC3527849 DOI: 10.3389/fendo.2012.00167] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/04/2012] [Indexed: 12/19/2022] Open
Abstract
Like most organisms, the nematode Caenorhabditis elegans relies heavily on neuropeptidergic signaling. This tiny animal represents a suitable model system to study neuropeptidergic signaling networks with single cell resolution due to the availability of powerful molecular and genetic tools. The availability of the worm's complete genome sequence allows researchers to browse through it, uncovering putative neuropeptides and their cognate G protein-coupled receptors (GPCRs). Many predictions have been made about the number of C. elegans neuropeptide GPCRs. In this review, we report the state of the art of both verified as well as predicted C. elegans neuropeptide GPCRs. The predicted neuropeptide GPCRs are incorporated into the receptor classification system based on their resemblance to orthologous GPCRs in insects and vertebrates. Appointing the natural ligand(s) to each predicted neuropeptide GPCR (receptor deorphanization) is a crucial step during characterization. The development of deorphanization strategies resulted in a significant increase in the knowledge of neuropeptidergic signaling in C. elegans. Complementary localization and functional studies demonstrate that neuropeptides and their GPCRs represent a rich potential source of behavioral variability in C. elegans. Here, we review all neuropeptidergic signaling pathways that so far have been functionally characterized in C. elegans.
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Affiliation(s)
- Lotte Frooninckx
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liesbeth Van Rompay
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liesbet Temmerman
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Elien Van Sinay
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Isabel Beets
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Tom Janssen
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Steven J. Husson
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liliane Schoofs
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
- *Correspondence: Liliane Schoofs, Laboratory of Functional Genomics and Proteomics, Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium. e-mail:
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Abstract
Extracellular signaling molecules have crucial roles in development and homeostasis, and their incorrect deployment can lead to developmental defects and disease states. Signaling molecules are released from sending cells, travel to target cells, and act over length scales of several orders of magnitude, from morphogen-mediated patterning of small developmental fields to hormonal signaling throughout the organism. We discuss how signals are modified and assembled for transport, which routes they take to reach their targets, and how their range is affected by mobility and stability.
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Affiliation(s)
- Patrick Müller
- Department of Molecular and Cellular Biology, Harvard Stem Cell Institute, Broad Institute, Center for Brain Science, FAS Center for Systems Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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Lo KY, Kuzmin A, Unger SM, Petersen JD, Silverman MA. KIF1A is the primary anterograde motor protein required for the axonal transport of dense-core vesicles in cultured hippocampal neurons. Neurosci Lett 2011; 491:168-73. [PMID: 21256924 DOI: 10.1016/j.neulet.2011.01.018] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 12/09/2010] [Accepted: 01/05/2011] [Indexed: 12/31/2022]
Abstract
Dense-core vesicles (DCVs) are responsible for transporting, processing, and secreting neuropeptide cargos that mediate a wide range of biological processes, including neuronal development, survival, and learning and memory. DCVs are synthesized in the cell body and are transported by kinesin motor proteins along microtubules to pre- and postsynaptic release sites. Due to the dependence on kinesin-based transport, we sought to determine if the kinesin-3 family member, KIF1A, transports DCVs in primary cultured hippocampal neurons, as has been described for invertebrate neurons. Two-color, live-cell imaging showed that the DCV markers, chromogranin A-RFP and BDNF-RFP, move together with KIF1A-GFP in both the anterograde and retrograde directions. To demonstrate a functional role for KIF1A in DCV transport, motor protein expression in neurons was reduced using RNA interference (shRNA). Fluorescently tagged DCV markers showed a significant reduction in organelle flux in cells expressing shRNA against KIF1A. The transport of cargo driven by motors other than KIF1A, including mitochondria and the transferrin receptor, was unaffected in KIF1A shRNA expressing cells. Taken together, these data support a primary role for KIF1A in the anterograde transport of DCVs in mammalian neurons, and also provide evidence that KIF1A remains associated with DCVs during retrograde DCV transport.
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Affiliation(s)
- K Y Lo
- Department of Biological Sciences, 8888 University Drive, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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Beug ST, Parks RJ, McBride HM, Wallace VA. Processing-dependent trafficking of Sonic hedgehog to the regulated secretory pathway in neurons. Mol Cell Neurosci 2010; 46:583-96. [PMID: 21182949 DOI: 10.1016/j.mcn.2010.12.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 11/25/2010] [Accepted: 12/09/2010] [Indexed: 01/22/2023] Open
Abstract
Neurons are an important source of the secreted morphogen Sonic hedgehog (Shh), however, little is known about neuron-specific regulation of Shh transport and secretion. To study this process, we investigated the subcellular distribution of Shh in primary neurons and differentiated cells of a neuroendocrine cell line by fluorescence microscopy and biochemical fractionation. In retinal ganglion cells, endogenous Shh was distributed as intra- and extracellular puncta at the soma, dendrites, axons and neurite terminals. Shh(+) puncta move bidirectionally and colocalize with markers of synaptic vesicles (SVs) and dense core granules. Lipid modification and proteolysis were required for Shh sorting to SVs and cell surface association. Finally, consistent with its association with regulated secretory vesicles, Shh secretion could be induced under depolarizing conditions. Taken together, these observations suggest that long-range Shh transport and signalling in neurons involves trafficking to the regulated secretory pathway and cell surface accumulation of Shh on axons and suggests a link between neuronal activity and Shh release.
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Affiliation(s)
- Shawn T Beug
- Vision Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada
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Wegrzyn JL, Bark SJ, Funkelstein L, Mosier C, Yap A, Kazemi-Esfarjani P, La Spada AR, Sigurdson C, O'Connor DT, Hook V. Proteomics of dense core secretory vesicles reveal distinct protein categories for secretion of neuroeffectors for cell-cell communication. J Proteome Res 2010; 9:5002-24. [PMID: 20695487 DOI: 10.1021/pr1003104] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Regulated secretion of neurotransmitters and neurohumoral factors from dense core secretory vesicles provides essential neuroeffectors for cell-cell communication in the nervous and endocrine systems. This study provides comprehensive proteomic characterization of the categories of proteins in chromaffin dense core secretory vesicles that participate in cell-cell communication from the adrenal medulla. Proteomic studies were conducted by nano-HPLC Chip MS/MS tandem mass spectrometry. Results demonstrate that these secretory vesicles contain proteins of distinct functional categories consisting of neuropeptides and neurohumoral factors, protease systems, neurotransmitter enzymes and transporters, receptors, enzymes for biochemical processes, reduction/oxidation regulation, ATPases, protein folding, lipid biochemistry, signal transduction, exocytosis, calcium regulation, as well as structural and cell adhesion proteins. The secretory vesicle proteomic data identified 371 proteins in the soluble fraction and 384 membrane proteins, for a total of 686 distinct secretory vesicle proteins. Notably, these proteomic analyses illustrate the presence of several neurological disease-related proteins in these secretory vesicles, including huntingtin interacting protein, cystatin C, ataxin 7, and prion protein. Overall, these findings demonstrate that multiple protein categories participate in dense core secretory vesicles for production, storage, and secretion of bioactive neuroeffectors for cell-cell communication in health and disease.
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Affiliation(s)
- Jill L Wegrzyn
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093, USA
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Janssen T, Lindemans M, Meelkop E, Temmerman L, Schoofs L. Coevolution of neuropeptidergic signaling systems: from worm to man. Ann N Y Acad Sci 2010; 1200:1-14. [PMID: 20633129 DOI: 10.1111/j.1749-6632.2010.05506.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the general knowledge and repeated predictions of peptide G protein-coupled receptors following the elucidation of the Caenorhabditis elegans genome in 1998, only a few have been deorphanized so far. This was attributed to the apparent lack of coevolution between (neuro)peptides and their cognate receptors. To resolve this issue, we have used an in silico genomic data mining tool to identify the real putative peptide GPCRs in the C. elegans genome and then made a well-considered selection of orphan peptide GPCRs. To maximize our chances of a successful deorphanization, we adopted a combined reverse pharmacology approach. At this moment, we have successfully uncovered four C. elegans neuropeptide signaling systems that support the theory of receptor-ligand coevolution. All four systems are extremely well conserved within nematodes and show a high degree of similarity with their vertebrate and arthropod counterparts. Our data indicate that these four neuropeptide signaling systems have been well conserved during the course of evolution and that they were already well established prior to the divergence of protostomes and deuterostomes.
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Affiliation(s)
- Tom Janssen
- Functional Genomics and Proteomics Unit, Department of Biology, KULeuven, Leuven, Belgium.
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Hammel I, Lagunoff D, Galli SJ. Regulation of secretory granule size by the precise generation and fusion of unit granules. J Cell Mol Med 2010; 14:1904-16. [PMID: 20406331 PMCID: PMC2909340 DOI: 10.1111/j.1582-4934.2010.01071.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 04/08/2010] [Indexed: 12/31/2022] Open
Abstract
Morphometric evidence derived from studies of mast cells, pancreatic acinar cells and other cell types supports a model in which the post-Golgi processes that generate mature secretory granules can be resolved into three steps: (1) fusion of small, Golgi-derived progranules to produce immature secretory granules which have a highly constrained volume; (2) transformation of such immature granules into mature secretory granules, a process often associated with a reduction in the maturing granule's volume, as well as changes in the appearance of its content and (3) fusion of secretory granules of the smallest size, termed 'unit granules', forming granules whose volumes are multiples of the unit granule's volume. Mutations which perturb this process can cause significant pathology. For example, Chediak-Higashi syndrome / lysosomal trafficking regulator (CHS)/(Lyst) mutations result in giant secretory granules in a number of cell types in human beings with the Chediak-Higashi syndrome and in 'beige' (Lyst(bg)/Lyst(bg)) mice. Analysis of the secretory granules of mast cells and pancreatic acinar cells in Lyst-deficient beige mice suggests that beige mouse secretory granules retain the ability to fuse randomly with other secretory granules no matter what the size of the fusion partners. By contrast, in normal mice, the pattern of granule-granule fusion occurs exclusively by the addition of unit granules, either to each other or to larger granules. The normal pattern of fusion is termed unit addition and the fusion evident in cells with CHS/Lyst mutations is called random addition. The proposed model of secretory granule formation has several implications. For example, in neurosecretory cells, the secretion of small amounts of cargo in granules constrained to a very narrow size increases the precision of the information conveyed by secretion. By contrast, in pancreatic acinar cells and mast cells, large granules composed of multiple unit granules permit the cells to store large amounts of material without requiring the amount of membrane necessary to package the same amount of cargo into small granules. In addition, the formation of mature secretory granules that are multimers of unit granules provides a mechanism for mixing in large granules the contents of unit granules which differ in their content of cargo.
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Affiliation(s)
- Ilan Hammel
- Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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17
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Curanovic D, Enquist L. Directional transneuronal spread of α-herpesvirus infection. Future Virol 2009; 4:591. [PMID: 20161665 DOI: 10.2217/fvl.09.62] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Most α-herpesviruses are pantropic, neuroinvasive pathogens that establish a reactivateable, latent infection in the PNS of their natural hosts. Various manifestations of herpes disease rely on extent and direction of the spread of infection between the surface epithelia and the nervous system components that innervate that surface. One aspect of such controlled spread of infection is the capacity for synaptically defined, transneuronal spread, a property that makes α-herpesviruses useful tools for determining the connectivity of neural circuits. The current understanding of intra-axonal transport and transneuronal spread of α-herpesviruses is reviewed, focusing on work with herpes simplex virus and pseudorabies virus, the available in vitro technology used to study viral transport and spread is evaluated and how certain viral mutants can be used to examine neural circuit architecture is described in this article.
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Affiliation(s)
- D Curanovic
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA
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18
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Sámano C, Zetina ME, Cifuentes F, Morales MA. Segregation of met-enkephalin from vesicular acetylcholine transporter and choline acetyltransferase in sympathetic preganglionic varicosities mostly lacking synaptophysin and synaptotagmin. Neuroscience 2009; 163:180-9. [PMID: 19524025 DOI: 10.1016/j.neuroscience.2009.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 06/03/2009] [Accepted: 06/04/2009] [Indexed: 11/28/2022]
Abstract
Sympathetic preganglionic neurons (SPN) coexpress the acetylcholine (ACh)-synthesizing enzyme choline acetyltransferase and different peptides in their cell bodies, but can express them independently in separate varicosities, indicating that SPN segregate transmitters to different synapses. Consequently, there are populations of preganglionic varicosities (peptidergic and noncholinergic) that store peptides but not ACh. We studied in the cell bodies and axon processes of the rat SPN the expression and the proportional coexpression of the vesicular ACh transporter-like immunoreactivity (VAChT), a specific marker of cholinergic synaptic vesicles or ChAT-like immunoreactivity (ChAT), and the peptide methionine enkephalin-like immunoreactivity (mENK), and confirmed the presence of a population of SPN peptidergic, noncholinergic varicosities. We characterized these varicosities by exploring the occurrence of synaptophysin-like immunoreactivity (Syn), a marker of small clear vesicles, and synaptotagmin-like immunoreactivity (Syt), a preferential marker of large dense core vesicles. We found that (i) VAChT and mENK, like ChAT-mENK, were coexpressed in only 59% of the mENK-containing varicosities, although they colocalized in the SPN cell bodies; and (ii) almost 60% of the population of mENK-containing varicosities did not express Syn or Syt, and over 80% of the mENK-containing varicosities negative for VAChT also lacked Syn. These data prove that SPN segregate mENK from VAChT and ChAT, and show that most of the subset of mENKergic varicosities negative for VAChT also does not express Syn, suggesting the presence of a different vesicular pattern in these sympathetic preganglionic varicosities.
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Affiliation(s)
- C Sámano
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 3er Circuito Exterior, Ciudad Universitaria, México, DF 04510, Mexico
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19
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de Wit J, Toonen RF, Verhage M. Matrix-dependent local retention of secretory vesicle cargo in cortical neurons. J Neurosci 2009; 29:23-37. [PMID: 19129381 PMCID: PMC6664920 DOI: 10.1523/jneurosci.3931-08.2009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 11/21/2008] [Accepted: 11/23/2008] [Indexed: 11/21/2022] Open
Abstract
Neurons secrete many diffusible signals from synaptic and other secretory vesicles. We characterized secretion of guidance cues, neuropeptides, neurotrophins, and proteases from single secretory vesicles using pHluorin-tagged cargo in cortical neurons. Stimulation triggered transient and persistent fusion events. Transient events represented full release followed by cargo diffusion or incomplete release followed by vesicle retrieval, as previously observed in neuroendocrine cells. Unexpectedly, we also observed that certain cargo, such as Semaphorin 3A (Sema3A), was delivered at the cell surface as stable deposits. Stable deposits and transient events were observed for single cargo and both were SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) and calcium dependent. The ratio between stable and transient events did not depend on cargo size, subcellular localization (synaptic vs extrasynaptic secretion), or the presence of the extracellular matrix. Instead, the ratio is cargo specific and depends on an interaction with the vesicle matrix through a basic domain in the cargo protein. Inhibition of this interaction through deletion of the basic domain in Sema3A abolished stable deposits and rendered all events transient. Strikingly, cargo favoring transient release was stably deposited after corelease with cargo favoring stable deposit. These data argue against cargo diffusion after exocytosis as a general principle. Instead, the vesicle matrix retains secreted signals, probably for focal signaling at the cell surface.
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Affiliation(s)
- Joris de Wit
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam (VUA) and VUA Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Ruud F. Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam (VUA) and VUA Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Matthijs Verhage
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam (VUA) and VUA Medical Center, 1081 HV Amsterdam, The Netherlands
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20
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Lochner JE, Spangler E, Chavarha M, Jacobs C, McAllister K, Schuttner LC, Scalettar BA. Efficient copackaging and cotransport yields postsynaptic colocalization of neuromodulators associated with synaptic plasticity. Dev Neurobiol 2008; 68:1243-56. [PMID: 18563704 DOI: 10.1002/dneu.20650] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Recent data suggest that tissue plasminogen activator (tPA) influences long-term plasticity at hippocampal synapses by converting plasminogen into plasmin, which then generates mature brain-derived neurotrophic factor (mBDNF) from its precursor, proBDNF. Motivated by this hypothesis, we used fluorescent chimeras, expressed in hippocampal neurons, to elucidate (1) mechanisms underlying plasminogen secretion from hippocampal neurons, (2) if tPA, plasminogen, and proBDNF are copackaged and cotransported in hippocampal neurons, especially within dendritic spines, and (3) mechanisms mediating the transport of these neuromodulators to sites of release. We find that plasminogen chimeras traffic through the regulated secretory pathway of hippocampal neurons in dense-core granules (DCGs) and that tPA, plasminogen, and proBDNF chimeras are extensively copackaged in DCGs throughout hippocampal neurons. We also find that 80% of spines that contain DCGs contain chimeras of these neuromodulators in the same DCG. Finally, we demonstrate, for the first time, that neuromodulators undergo cotransport along dendrites in rapidly mobile DCGs, indicating that neuromodulators can be efficiently recruited into active spines. These results support the hypothesis that tPA mediates synaptic activation of BDNF by demonstrating that tPA, plasminogen, and proBDNF colocalize in DCGs in spines, where these neuromodulators can undergo activity-dependent release and then interact and/or mediate changes that influence synaptic efficacy. The results also raise the possibility that frequency-dependent changes in extents of neuromodulator release from DCGs influence the direction of plasticity at hippocampal synapses by altering the relative proportions of two proteins, mBDNF and proBDNF, that exert opposing effects on synaptic efficacy.
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Affiliation(s)
- J E Lochner
- Department of Chemistry, Lewis & Clark College, Portland, Oregon 97219, USA
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21
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Insulin action on glucose transporters through molecular switches, tracks and tethers. Biochem J 2008; 413:201-15. [DOI: 10.1042/bj20080723] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Glucose entry into muscle cells is precisely regulated by insulin, through recruitment of GLUT4 (glucose transporter-4) to the membrane of muscle and fat cells. Work done over more than two decades has contributed to mapping the insulin signalling and GLUT4 vesicle trafficking events underpinning this response. In spite of this intensive scientific research, there are outstanding questions that continue to challenge us today. The present review summarizes the knowledge in the field, with emphasis on the latest breakthroughs in insulin signalling at the level of AS160 (Akt substrate of 160 kDa), TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) and their target Rab proteins; in vesicle trafficking at the level of vesicle mobilization, tethering, docking and fusion with the membrane; and in the participation of the cytoskeleton to achieve optimal temporal and spatial location of insulin-derived signals and GLUT4 vesicles.
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22
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Levitan ES. Signaling for vesicle mobilization and synaptic plasticity. Mol Neurobiol 2008; 37:39-43. [PMID: 18446451 DOI: 10.1007/s12035-008-8014-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 03/17/2008] [Indexed: 10/22/2022]
Abstract
The hypothesis that release of classical neurotransmitters and neuropeptides is facilitated by increasing the mobility of small synaptic vesicles (SSVs) and dense core vesicles (DCVs) could not be tested until the advent of methods for visualizing these secretory vesicles in living nerve terminals. In fact, fluorescence imaging studies have only since 2005 established that activity increases secretory vesicle mobility in motoneuron terminals and chromaffin cells. Mobilization of DCVs and SSVs appears to be due to liberation of hindered vesicles to promote quicker diffusion. However, F-actin and synapsin, which have been featured in mobilization models, are not required for activity-dependent increases in the mobility of DCVs or SSVs. Most recently, the signaling required for sustained mobilization has been identified for Drosophila motoneuron DCVs and shown to increase synaptic transmission. Specifically, presynaptic endoplasmic reticulum ryanodine receptor-mediated Ca2+ release activates Ca2+/calmodulin-dependent kinase II to mobilize DCVs and induce post-tetanic potentiation (PTP) of neuropeptide release in the Drosophila neuromuscular junction. The shared signaling for increasing vesicle mobility and PTP links vesicle mobilization and synaptic plasticity.
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Affiliation(s)
- Edwin S Levitan
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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23
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Abstract
Total internal reflection fluorescence microscopy (TIRFM), also known as evanescent wave microscopy, is used in a wide range of applications, particularly to view single molecules attached to planar surfaces and to study the position and dynamics of molecules and organelles in living culture cells near the contact regions with the glass coverslip. TIRFM selectively illuminates fluorophores only in a very thin (less than 100 nm deep) layer near the substrate, thereby avoiding excitation of fluorophores outside this subresolution optical section. This chapter reviews the history, current applications in cell biology and biochemistry, basic optical theory, combinations with numerous other optical and spectroscopic approaches, and a range of setup methods, both commercial and custom.
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Affiliation(s)
- Daniel Axelrod
- Departments of Physics and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, USA
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24
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Cifuentes F, Montoya M, Morales M. High-frequency stimuli preferentially release large dense-core vesicles located in the proximity of nonspecialized zones of the presynaptic membrane in sympathetic ganglia. Dev Neurobiol 2008; 68:446-56. [DOI: 10.1002/dneu.20604] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Shakiryanova D, Klose MK, Zhou Y, Gu T, Deitcher DL, Atwood HL, Hewes RS, Levitan ES. Presynaptic ryanodine receptor-activated calmodulin kinase II increases vesicle mobility and potentiates neuropeptide release. J Neurosci 2007; 27:7799-806. [PMID: 17634373 PMCID: PMC6672873 DOI: 10.1523/jneurosci.1879-07.2007] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although it has been postulated that vesicle mobility is increased to enhance release of transmitters and neuropeptides, the mechanism responsible for increasing vesicle motion in nerve terminals and the effect of perturbing this mobilization on synaptic plasticity are unknown. Here, green fluorescent protein-tagged dense-core vesicles (DCVs) are imaged in Drosophila motor neuron terminals, where DCV mobility is increased for minutes after seconds of activity. Ca2+-induced Ca2+ release from presynaptic endoplasmic reticulum (ER) is shown to be necessary and sufficient for sustained DCV mobilization. However, this ryanodine receptor (RyR)-mediated effect is short-lived and only initiates signaling. Calmodulin kinase II (CaMKII), which is not activated directly by external Ca2+ influx, then acts as a downstream effector of released ER Ca2+. RyR and CaMKII are essential for post-tetanic potentiation of neuropeptide secretion. Therefore, the presynaptic signaling pathway for increasing DCV mobility is identified and shown to be required for synaptic plasticity.
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Affiliation(s)
- Dinara Shakiryanova
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Markus K. Klose
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Yi Zhou
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Tingting Gu
- Departments of Zoology and Cell Biology, University of Oklahoma, Norman, Oklahoma 73019, and
| | - David L. Deitcher
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
| | - Harold L. Atwood
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Randall S. Hewes
- Departments of Zoology and Cell Biology, University of Oklahoma, Norman, Oklahoma 73019, and
| | - Edwin S. Levitan
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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26
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Li BX, Satoh AK, Ready DF. Myosin V, Rab11, and dRip11 direct apical secretion and cellular morphogenesis in developing Drosophila photoreceptors. ACTA ACUST UNITED AC 2007; 177:659-69. [PMID: 17517962 PMCID: PMC2064211 DOI: 10.1083/jcb.200610157] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Sensory neuron terminal differentiation tasks apical secretory transport with delivery of abundant biosynthetic traffic to the growing sensory membrane. We recently showed Drosophila Rab11 is essential for rhodopsin transport in developing photoreceptors and asked here if myosin V and the Drosophila Rab11 interacting protein, dRip11, also participate in secretory transport. Reduction of either protein impaired rhodopsin transport, stunting rhabdomere growth and promoting accumulation of cytoplasmic rhodopsin. MyoV-reduced photoreceptors also developed ectopic rhabdomeres inappropriately located in basolateral membrane, indicating a role for MyoV in photoreceptor polarity. Binary yeast two hybrids and in vitro protein–protein interaction predict a ternary complex assembled by independent dRip11 and MyoV binding to Rab11. We propose this complex delivers morphogenic secretory traffic along polarized actin filaments of the subcortical terminal web to the exocytic plasma membrane target, the rhabdomere base. A protein trio conserved across eukaryotes thus mediates normal, in vivo sensory neuron morphogenesis.
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Affiliation(s)
- Bingbing X Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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27
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Mohapatra DP, Vacher H, Trimmer JS. The Surprising Catch of a Voltage-Gated Potassium Channel in a Neuronal SNARE. ACTA ACUST UNITED AC 2007; 2007:pe37. [PMID: 17609479 DOI: 10.1126/stke.3932007pe37] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Among ion channels, voltage-gated calcium channels have been considered unique in their ability to mediate signaling events independent of the flow of ions through their pore. A voltage-gated potassium channel termed Kv2.1 has been identified as playing a role remarkably similar to one ion-independent function of calcium channels, facilitating regulated exocytosis through a direct interaction with a t-SNARE [soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptor] component of the vesicle release machinery. Kv2.1 overexpression enhances depolarization-induced secretion from the neuroendocrine-like PC12 cell line, and a nonconducting Kv2.1 mutant can accomplish the same feat. Kv2.1 interacts directly with syntaxin 1A, a plasma membrane t-SNARE component of the vesicle docking and fusion apparatus. Deletion of the syntaxin 1A-binding segment from Kv2.1 abolishes its ability to promote vesicle release, supporting a mechanism whereby Kv2.1 presumably transfers voltage-dependent conformational changes induced by membrane depolarization to interacting t-SNAREs to affect exocytosis. Kv2.1, a major mediator of electrical events in central neurons, cardiac and smooth muscle, and pancreatic beta cells, must now also be recognized as a physical mediator of secretion. That Kv2.1 is phosphorylated at numerous sites within the syntaxin 1A binding segment raises the possibility that its role in secretion may be dynamically regulated by diverse signaling events.
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Affiliation(s)
- Durga P Mohapatra
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, USA
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28
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Tessmar-Raible K. The evolution of neurosecretory centers in bilaterian forebrains: insights from protostomes. Semin Cell Dev Biol 2007; 18:492-501. [PMID: 17576082 DOI: 10.1016/j.semcdb.2007.04.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 04/30/2007] [Indexed: 02/08/2023]
Abstract
Forebrain neurosecretory systems are widespread in the animal kingdom. This review focuses on recent molecular data from protostomes, discusses the original complexity of the bilaterian forebrain neurosecretory system, provides an evolutionary scenario for the emergence of the vertebrate preoptic area/hypothalamus/neurohypophysis and suggests a possible function for an ancient set of sensory-neurosecretory cells present in the medial neurosecretory bilaterian forebrain.
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Affiliation(s)
- Kristin Tessmar-Raible
- European Molecular Biology Laboratory, Dev. Biol. Unit, Meyerhofstr. 1, D-69012 Heidelberg, Germany.
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29
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Husson SJ, Mertens I, Janssen T, Lindemans M, Schoofs L. Neuropeptidergic signaling in the nematode Caenorhabditis elegans. Prog Neurobiol 2007; 82:33-55. [PMID: 17383075 DOI: 10.1016/j.pneurobio.2007.01.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 12/14/2006] [Accepted: 01/29/2007] [Indexed: 11/25/2022]
Abstract
The nematode Caenorhabditis elegans joins the menagerie of behavioral model systems next to the fruit fly Drosophila melanogaster, the marine snail Aplysia californica and the mouse. In contrast to Aplysia, which contains 20,000 neurons having cell bodies of hundreds of microns in diameter, C. elegans harbors only 302 tiny neurons from which the cell lineage is completely described, as is the case for all the other somatic cells. As such, this nervous system appears at first sight incommensurable with those of higher organisms, although genome-wide comparison of predicted C. elegans genes with their counterparts in vertebrates revealed many parallels. Together with its short lifespan and ease of cultivation, suitability for high-throughput genetic screenings and genome-wide RNA interference approaches, access to an advanced genetic toolkit and cell-ablation techniques, it seems that this tiny transparent organism of only 1mm in length has nothing to hide. Recently, highly exciting developments have occurred within the field of neuropeptidergic signaling in C. elegans, not only because of the availability of a sequenced genome since 1998, but especially because of state of the art post genomic technologies, that allow for molecular characterization of the signaling molecules. Here, we will focus on endogenous, bioactive (neuro)peptides and mainly discuss biosynthesis, peptide sequence information, localization and G-protein coupled receptors of the three major peptide families in C. elegans.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics Unit, Department of Biology, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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30
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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] [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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31
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Abstract
By taking advantage of combinations of the many rich properties of photons, new forms of optical microscopy can now be used to visualize features of samples beyond thickness and density variations. We are now within reach of viewing the motions, orientations, binding kinetics and specific transient associations of previously 'submicroscopic' cellular structures and single molecules.
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Affiliation(s)
- Daniel Axelrod
- Department of Physics & Biophysics Research Division, University of Michigan, Ann Arbor, Michigan 48109, USA.
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