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Xiong H, Wilson BA, Slesinger PA, Qin Z. Understanding Neuropeptide Transmission in the Brain by Optical Uncaging and Release. ACS Chem Neurosci 2023; 14:516-523. [PMID: 36719384 PMCID: PMC10302814 DOI: 10.1021/acschemneuro.2c00684] [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] [Indexed: 02/01/2023] Open
Abstract
Neuropeptides are abundant and essential signaling molecules in the nervous system involved in modulating neural circuits and behavior. Neuropeptides are generally released extrasynaptically and signal via volume transmission through G-protein-coupled receptors (GPCR). Although substantive functional roles of neuropeptides have been discovered, many questions on neuropeptide transmission remain poorly understood, including the local diffusion and transmission properties in the brain extracellular space. To address this challenge, intensive efforts are required to develop advanced tools for releasing and detecting neuropeptides with high spatiotemporal resolution. Because of the rapid development of biosensors and materials science, emerging tools are beginning to provide a better understanding of neuropeptide transmission. In this perspective, we summarize the fundamental advances in understanding neuropeptide transmission over the past decade, highlight the tools for releasing neuropeptides with high spatiotemporal solution in the brain, and discuss open questions and future directions in the field.
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Affiliation(s)
- Hejian Xiong
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Blake A. Wilson
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zhenpeng Qin
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75080, USA
- Department of Surgery, The University of Texas at Southwestern Medical Center, Dallas, TX 75390, USA
- Center for Advanced Pain Studies, The University of Texas at Dallas, Richardson, TX 75080, USA
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Han Y, Ding K. Imaging Neuropeptide Release at Drosophila Neuromuscular Junction with a Genetically Engineered Neuropeptide Release Reporter. Methods Mol Biol 2022; 2417:193-203. [PMID: 35099801 DOI: 10.1007/978-1-0716-1916-2_15] [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] [Indexed: 06/14/2023]
Abstract
Despite the important roles of neuropeptides in a variety of physiological processes, there still lacks a method to probe neuropeptide release events in vivo with satisfying temporal and spatial resolution. Neuropeptide Release Reporter (NPRR) was recently introduced as a novel genetically encoded indicator of neuropeptide release with a high temporal resolution and peptide specificity based on GCaMP molecule. Here we describe a method for using NPRR to image selective neuropeptide release at Drosophila neuromuscular junction in semi-dissected larvae. This method provides a quantitative analysis of activity-dependent neuropeptide release as real-time changes in fluorescence intensity of GCaMP reporter with sub-second temporal resolution and single bouton specificity.
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Affiliation(s)
- Yifu Han
- Department of Neurobiology, University of Southern California, Los Angeles, CA, USA.
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, USA.
| | - Keke Ding
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
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Hoffmann T, Kistner K, Joksimovic SLJ, Todorovic SM, Reeh PW, Sauer SK. Painful diabetic neuropathy leads to functional Ca V3.2 expression and spontaneous activity in skin nociceptors of mice. Exp Neurol 2021; 346:113838. [PMID: 34450183 PMCID: PMC8549116 DOI: 10.1016/j.expneurol.2021.113838] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 04/20/2021] [Revised: 07/15/2021] [Accepted: 08/07/2021] [Indexed: 12/26/2022]
Abstract
Painful diabetic neuropathy occurs in approximately 20% of diabetic patients with underlying pathomechanisms not fully understood. We evaluated the contribution of the CaV3.2 isoform of T-type calcium channel to hyperglycemia-induced changes in cutaneous sensory C-fiber functions and neuropeptide release employing the streptozotocin (STZ) diabetes model in congenic mouse strains including global knockouts (KOs). Hyperglycemia established for 3-5 weeks in male C57BL/6J mice led to major reorganizations in peripheral C-fiber functions. Unbiased electrophysiological screening of mechanosensitive single-fibers in isolated hairy hindpaw skin revealed a relative loss of (polymodal) heat sensing in favor of cold sensing. In healthy CaV3.2 KO mice both heat and cold sensitivity among the C-fibers seemed underrepresented in favor of exclusive mechanosensitivity, low-threshold in particular, which deficit became significant in the diabetic KOs. Diabetes also led to a marked increase in the incidence of spontaneous discharge activity among the C-fibers of wildtype mice, which was reduced by the specific CaV3.2 blocker TTA-P2 and largely absent in the KOs. Evaluation restricted to the peptidergic class of nerve fibers - measuring KCl-stimulated CGRP release - revealed a marked reduction in the sciatic nerve by TTA-P2 in healthy but not diabetic wildtypes, the latter showing CGRP release that was as much reduced as in healthy and, to the same extent, in diabetic CaV3.2 KOs. These data suggest that diabetes abrogates all CaV3.2 functionality in the peripheral nerve axons. In striking contrast, diabetes markedly increased the KCl-stimulated CGRP release from isolated hairy skin of wildtypes but not KO mice, and TTA-P2 reversed this increase, strongly suggesting a de novo expression of CaV3.2 in peptidergic cutaneous nerve endings which may contribute to the enhanced spontaneous activity. De-glycosylation by neuraminidase showed clear desensitizing effects, both in regard to spontaneous activity and stimulated CGRP release, but included actions independent of CaV3.2. However, as diabetes-enhanced glycosylation is decisive for intra-axonal trafficking, it may account for the substantial reorganizations of the CaV3.2 distribution. The results may strengthen the validation of CaV3.2 channel as a therapeutic target of treating painful diabetic neuropathy.
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Affiliation(s)
- Tal Hoffmann
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Katrin Kistner
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Sonja L J Joksimovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Peter W Reeh
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany
| | - Susanne K Sauer
- Institute for Physiology and Pathophysiology, University of Erlangen-Nuremberg, Universitaetsstrasse 17, 91054 Erlangen, Germany.
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Nässel DR, Vanden Broeck J. Insulin/IGF signaling in Drosophila and other insects: factors that regulate production, release and post-release action of the insulin-like peptides. Cell Mol Life Sci 2016; 73:271-90. [PMID: 26472340 PMCID: PMC11108470 DOI: 10.1007/s00018-015-2063-3] [Citation(s) in RCA: 197] [Impact Index Per Article: 24.6] [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: 09/02/2015] [Revised: 10/01/2015] [Accepted: 10/05/2015] [Indexed: 01/02/2023]
Abstract
Insulin, insulin-like growth factors (IGFs) and insulin-like peptides (ILPs) are important regulators of metabolism, growth, reproduction and lifespan, and mechanisms of insulin/IGF signaling (IIS) have been well conserved over evolution. In insects, between one and 38 ILPs have been identified in each species. Relatively few insect species have been investigated in depth with respect to ILP functions, and therefore we focus mainly on the well-studied fruitfly Drosophila melanogaster. In Drosophila eight ILPs (DILP1-8), but only two receptors (dInR and Lgr3) are known. DILP2, 3 and 5 are produced by a set of neurosecretory cells (IPCs) in the brain and their biosynthesis and release are controlled by a number of mechanisms differing between larvae and adults. Adult IPCs display cell-autonomous sensing of circulating glucose, coupled to evolutionarily conserved mechanisms for DILP release. The glucose-mediated DILP secretion is modulated by neurotransmitters and neuropeptides, as well as by factors released from the intestine and adipocytes. Larval IPCs, however, are indirectly regulated by glucose-sensing endocrine cells producing adipokinetic hormone, or by circulating factors from the intestine and fat body. Furthermore, IIS is situated within a complex physiological regulatory network that also encompasses the lipophilic hormones, 20-hydroxyecdysone and juvenile hormone. After release from IPCs, the ILP action can be modulated by circulating proteins that act either as protective carriers (binding proteins), or competitive inhibitors. Some of these proteins appear to have additional functions that are independent of ILPs. Taken together, the signaling with multiple ILPs is under complex control, ensuring tightly regulated IIS in the organism.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, 10691, Stockholm, Sweden.
| | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction, Department of Animal Physiology and Neurobiology, Zoological Institute, K.U. Leuven, Louvain, Belgium
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Hoover CM, Edwards SL, Yu SC, Kittelmann M, Richmond JE, Eimer S, Yorks RM, Miller KG. A novel CaM kinase II pathway controls the location of neuropeptide release from Caenorhabditis elegans motor neurons. Genetics 2014; 196:745-65. [PMID: 24653209 PMCID: PMC3948804 DOI: 10.1534/genetics.113.158568] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [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: 10/22/2013] [Accepted: 11/17/2013] [Indexed: 12/29/2022] Open
Abstract
Neurons release neuropeptides via the regulated exocytosis of dense core vesicles (DCVs) to evoke or modulate behaviors. We found that Caenorhabditis elegans motor neurons send most of their DCVs to axons, leaving very few in the cell somas. How neurons maintain this skewed distribution and the extent to which it can be altered to control DCV numbers in axons or to drive release from somas for different behavioral impacts is unknown. Using a forward genetic screen, we identified loss-of-function mutations in UNC-43 (CaM kinase II) that reduce axonal DCV levels by ∼90% and cell soma/dendrite DCV levels by ∼80%, leaving small synaptic vesicles largely unaffected. Blocking regulated secretion in unc-43 mutants restored near wild-type axonal levels of DCVs. Time-lapse video microscopy showed no role for CaM kinase II in the transport of DCVs from cell somas to axons. In vivo secretion assays revealed that much of the missing neuropeptide in unc-43 mutants is secreted via a regulated secretory pathway requiring UNC-31 (CAPS) and UNC-18 (nSec1). DCV cargo levels in unc-43 mutants are similarly low in cell somas and the axon initial segment, indicating that the secretion occurs prior to axonal transport. Genetic pathway analysis suggests that abnormal neuropeptide function contributes to the sluggish basal locomotion rate of unc-43 mutants. These results reveal a novel pathway controlling the location of DCV exocytosis and describe a major new function for CaM kinase II.
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Affiliation(s)
- Christopher M. Hoover
- Genetic Models of Disease Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Stacey L. Edwards
- Genetic Models of Disease Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Szi-chieh Yu
- Department of Biological Sciences, University of Illinois, Chicago, Illinois 60607
| | - Maike Kittelmann
- European Neuroscience Institute, Center for Molecular Physiology of the Brain, Georg-August University, Goettingen, Germany 37073
| | - Janet E. Richmond
- Department of Biological Sciences, University of Illinois, Chicago, Illinois 60607
| | - Stefan Eimer
- European Neuroscience Institute, Center for Molecular Physiology of the Brain, Georg-August University, Goettingen, Germany 37073
- BIOSS Center for Biological Signaling Studies, Albert-Ludwigs-University, Freiburg, Germany 79085
| | - Rosalina M. Yorks
- Genetic Models of Disease Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Kenneth G. Miller
- Genetic Models of Disease Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
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Pittman SK, Gracias NG, Vasko MR, Fehrenbacher JC. Paclitaxel alters the evoked release of calcitonin gene-related peptide from rat sensory neurons in culture. Exp Neurol 2014; 253:146-53. [PMID: 24374060 PMCID: PMC5954981 DOI: 10.1016/j.expneurol.2013.12.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [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: 09/17/2013] [Revised: 12/12/2013] [Accepted: 12/17/2013] [Indexed: 01/03/2023]
Abstract
Peripheral neuropathy (PN) is a debilitating and dose-limiting side effect of treatment with the chemotherapeutic agent, paclitaxel. Understanding the effects of paclitaxel on sensory neuronal function and the signaling pathways which mediate these paclitaxel-induced changes in function are critical for the development of therapies to prevent or alleviate the PN. The effects of long-term administration of paclitaxel on the function of sensory neurons grown in culture, using the release of the neuropeptide calcitonin gene-related peptide (CGRP) as an endpoint of sensory neuronal function, were examined. Dorsal root ganglion cultures were treated with low (10 nM) and high (300 nM) concentrations of paclitaxel for 1, 3, or 5 days. Following paclitaxel treatment, the release of CGRP was determined using capsaicin, a TRPV1 agonist; allyl isothiocyanate (AITC), a TRPA1 agonist; or high extracellular potassium. The effects of paclitaxel on the release of CGRP were stimulant-, concentration-, and time-dependent. When neurons were stimulated with capsaicin or AITC, a low concentration of paclitaxel (10nM) augmented transmitter release, whereas a high concentration (300 nM) reduced transmitter release in a time-dependent manner; however, when high extracellular potassium was used as the evoking stimulus, all concentrations of paclitaxel augmented CGRP release from sensory neurons. These results suggest that paclitaxel alters the function of sensory neurons in vitro, and suggest that the mechanisms by which paclitaxel alters neuronal function may include functional changes in TRP channel activity. The described in vitro model will facilitate future studies to identify the signaling pathways by which paclitaxel alters neuronal sensitivity.
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Affiliation(s)
- Sherry K Pittman
- Indiana University School of Medicine, Department of Pharmacology and Toxicology, USA.
| | - Neilia G Gracias
- Indiana University School of Medicine, Department of Pharmacology and Toxicology, USA; Indiana University School of Medicine, Stark Neuroscience Research Institute, USA; Columbia University, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, USA.
| | - Michael R Vasko
- Indiana University School of Medicine, Department of Pharmacology and Toxicology, USA; Indiana University School of Medicine, Stark Neuroscience Research Institute, USA; Indiana University School of Medicine, Department of Anesthesiology, USA.
| | - Jill C Fehrenbacher
- Indiana University School of Medicine, Department of Pharmacology and Toxicology, USA; Indiana University School of Medicine, Stark Neuroscience Research Institute, USA; Indiana University School of Medicine, Department of Anesthesiology, USA.
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