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Waller TJ, Smithson LJ, Collins CA. Peripheral Nerve Crush in Drosophila Larvae. Cold Spring Harb Protoc 2024:pdb.prot108169. [PMID: 38649195 DOI: 10.1101/pdb.prot108169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The long length of axons makes them vulnerable to damage; hence, it is logical that nervous systems have evolved adaptive mechanisms for responding to axon damage. Studies in Drosophila melanogaster have identified evolutionarily conserved molecular pathways that enable axonal degeneration and regeneration of damaged axons and/or dendrites. This protocol describes a simple method for inducing nerve crush injury to motoneuron and sensory neuron axons in the peripheral (segmental) nerves in second- or early third-instar larvae. Small forceps are used to pinch the cuticle at a location that overlays the segmental nerves. Although the connective tissue of the nerves remains intact and the larva survives the injury, single motoneuron and sensory neuron axons incur a break in continuity at the damage site and then undergo Wallerian degeneration distal to the break. This degeneration includes the dismantling of neuromuscular junction (NMJ) synapses formed by the axons that incurred damage. With stereotyped anatomy and accessibility to structural and electrophysiological studies, the larval NMJ is a good model to characterize the cellular changes that occur in synapses undergoing degeneration and to identify conditions that can protect axons and synapses from degeneration.
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Affiliation(s)
- Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Laura J Smithson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Waller TJ, Smithson LJ, Collins CA. Study of Axonal Injury and Degeneration in Drosophila. Cold Spring Harb Protoc 2024:pdb.top108163. [PMID: 38649194 DOI: 10.1101/pdb.top108163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
A fundamental feature of nervous systems is a highly specified synaptic connectivity between cells and the ability to adaptively change this connectivity through plasticity mechanisms. Plasticity mechanisms are highly relevant for responding to nervous system damage, and studies using nervous system injury paradigms in Drosophila (as well as other model organisms) have revealed conserved molecular pathways that are triggered by axon damage. Simple assays that introduce injuries to axons in either adult flies or larvae have proven to be particularly powerful for uncovering mechanisms of axonal degeneration and clearance. They have also been used to reveal requirements for regrowth of axons and dendrites, as well as signaling pathways that regulate cellular responses to nerve injury. Here we review commonly used and simple to carry out techniques that enable experimenters to study responses to axonal damage in either adult flies (following antennal transection) or larvae (following nerve crush to segmental nerves). Because axons and dendrites in the larval peripheral nervous system can be readily visualized through the translucent cuticle, another versatile method to probe injury responses is to focus high-energy laser light to a small and specific location in the animal. We therefore discuss a method for immobilizing intact larvae for imaging through the cuticle to carry out injury by pulse dye laser, which can be used to generate many different kinds of injuries and directed ablations within intact larvae. These techniques, combined with powerful genetic tools in Drosophila, make the fruit fly an excellent model system for studying the effects of injury and the mechanisms of axon degeneration, synapse plasticity, and immune response.
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Affiliation(s)
- Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Laura J Smithson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Waller TJ, Smithson LJ, Collins CA. Wallerian Degeneration and Clearance of Olfactory Receptor Neuron Axons following Drosophila Antennal Transection. Cold Spring Harb Protoc 2024:pdb.prot108167. [PMID: 38649191 DOI: 10.1101/pdb.prot108167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Neurons extend their axons and dendrites over long distances and rely on evolutionarily conserved mechanisms to maintain the cellular structure and function of neurites at a distance from their cell body. Neurites that lose connection with their cell body following damage or stressors to their cytoskeleton undergo a programmed self-destruction process akin to apoptosis but using different cellular machinery, termed Wallerian degeneration. While first described for vertebrate axons by Augustus Waller in 1850, key discoveries of the enzymes that regulate Wallerian degeneration were made through forward genetic screens in Drosophila melanogaster Powerful techniques for genetic manipulation and visualization of single neurons combined with simple methods for introducing axotomy (neuron severing) to certain neuron types in Drosophila have enabled the discovery and study of the cellular machinery responsible for Wallerian degeneration, in addition to mechanisms that enable clearance of the resulting debris. This protocol describes how to study the degeneration and clearance of axons from olfactory receptor neurons (ORNs). These peripheral neurons reside in the antennae and project axons to olfactory glomeruli of the anterior brain. Simple and nonlethal removal of antennae from adult flies causes axotomy of ORNs, and the fate of the injured axons can be readily visualized in a whole-mount dissected brain. This assay takes advantage of well-characterized genetic methods to robustly and specifically label subsets of ORNs. This method of neurite labeling and axotomy was the first axon injury paradigm to be developed in flies and is still regularly used due to its simplicity to perform, dissect, image, and analyze.
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Affiliation(s)
- Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Laura J Smithson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Smithson LJ, Waller TJ, Collins CA. Laser Microsurgery in Drosophila Larvae Using the MicroPoint Ablation System. Cold Spring Harb Protoc 2024:pdb.prot108171. [PMID: 38649192 DOI: 10.1101/pdb.prot108171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Laser microsurgery is a robust method to ablate specific cells in the nervous system and probe the functional consequences of their loss in the animal. By introducing focal lesions to small locations in the animal, laser microsurgery also enables disruptions of specific connections within neuronal circuits and the study of how the nervous system responds to precise forms of damage (for instance, damage to specific axons or dendrites, which have been found to evoke different kinds of responses in neurons). The MicroPoint laser is a pulsed dye laser that can be mounted onto any standard microscope, hence is an affordable alternative to two-photon lasers for providing high powered focal ablations. This protocol describes how to use a MicroPoint laser ablation system to induce focal injuries in Drosophila larvae. This protocol guides a user who has access to a MicroPoint laser that has already been installed onto an appropriate microscope for high-resolution imaging and configured for laser ablation using Coumarin 440 dye. The protocol covers how to use the laser to carry out surgeries or ablation, how to change the laser dye and calibrate the power settings, and how to make sure the laser is properly focused. While the protocol provides an example of axotomy (axon severing) in the peripheral nervous system of Drosophila larvae, use of the MicroPoint system can be adapted to other focal surgeries in other organisms.
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Affiliation(s)
- Laura J Smithson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Smithson LJ, Waller TJ, Collins CA. Immobilizing Second-Instar Drosophila Larvae for Imaging and Surgery Using the Larva Chip. Cold Spring Harb Protoc 2024:pdb.prot108170. [PMID: 38649193 DOI: 10.1101/pdb.prot108170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The simple body plan and semitranslucent cuticle of the Drosophila larva allow for imaging of structures close to the body wall within intact animals. These include sensory neurons, muscles, neuromuscular junctions, and some regions of the segmental nerve. However, imaging within an intact larva requires a strategy to immobilize the animal in a position that presents the structures within the working distance of the microscope objective. Although various methods have been implemented for Drosophila larvae, this protocol describes a simple and noninvasive method that makes use of the polydimethylsiloxane (PDMS) larva chip. This larva chip immobilizes animals without the use of anesthetics or changes in temperature, which alter neuronal physiology, making it suitable for calcium imaging of endogenous activity in live animals. The membrane is air-permeable. Animals robustly survive short periods of immobilization (up to 30 min) and can even survive longer time periods. Since animals recover well after the procedure, the same animal can be reimaged multiple times. This makes the method amenable to manipulations such as laser microsurgery, photobleaching, and photoconversion followed by imaging of outcomes of these manipulations over time.
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Affiliation(s)
- Laura J Smithson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Schmitd LB, Hafner H, Ward A, Asghari Adib E, Biscola NP, Kohen R, Patel M, Williamson RE, Desai E, Bennett J, Saxman G, Athaiya M, Wilborn D, Shumpert J, Zhao XF, Kawaguchi R, Geschwind DH, Hoke A, Shrager P, Collins CA, Havton LA, Kalinski AL, Giger RJ. Sarm1 is not necessary for activation of neuron-intrinsic growth programs yet required for the Schwann cell repair response and peripheral nerve regeneration. bioRxiv 2024:2024.03.04.583374. [PMID: 38496662 PMCID: PMC10942360 DOI: 10.1101/2024.03.04.583374] [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] [Indexed: 03/19/2024]
Abstract
Upon peripheral nervous system (PNS) injury, severed axons undergo rapid SARM1-dependent Wallerian degeneration (WD). In mammals, the role of SARM1 in PNS regeneration, however, is unknown. Here we demonstrate that Sarm1 is not required for axotomy induced activation of neuron-intrinsic growth programs and axonal growth into a nerve crush site. However, in the distal nerve, Sarm1 is necessary for the timely induction of the Schwann cell (SC) repair response, nerve inflammation, myelin clearance, and regeneration of sensory and motor axons. In Sarm1-/- mice, regenerated fibers exhibit reduced axon caliber, defective nerve conduction, and recovery of motor function is delayed. The growth hostile environment of Sarm1-/- distal nerve tissue was demonstrated by grafting of Sarm1-/- nerve into WT recipients. SC lineage tracing in injured WT and Sarm1-/- mice revealed morphological differences. In the Sarm1-/- distal nerve, the appearance of p75NTR+, c-Jun+ SCs is significantly delayed. Ex vivo, p75NTR and c-Jun upregulation in Sarm1-/- nerves can be rescued by pharmacological inhibition of ErbB kinase. Together, our studies show that Sarm1 is not necessary for the activation of neuron intrinsic growth programs but in the distal nerve is required for the orchestration of cellular programs that underlie rapid axon extension.
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Affiliation(s)
- Ligia B. Schmitd
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - Hannah Hafner
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - Ayobami Ward
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor MI, USA
| | - Elham Asghari Adib
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Natalia P. Biscola
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Rafi Kohen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - Manav Patel
- Department of Biology, Ball State University, Muncie IN, USA
| | | | - Emily Desai
- Department of Biology, Ball State University, Muncie IN, USA
| | | | - Grace Saxman
- Department of Biology, Ball State University, Muncie IN, USA
| | - Mitre Athaiya
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - David Wilborn
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - Jaisha Shumpert
- Department of Biology, Ball State University, Muncie IN, USA
| | - Xiao-Feng Zhao
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
| | - Riki Kawaguchi
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Daniel H. Geschwind
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
- Institute of Precision Health, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ahmet Hoke
- Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA
| | - Peter Shrager
- Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Catherine A. Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Leif A. Havton
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- James J Peters VA Medical Center, Bronx, NY, USA
| | - Ashley L. Kalinski
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
- Department of Biology, Ball State University, Muncie IN, USA
| | - Roman J. Giger
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor MI, USA
- Department of Neurology, University of Michigan Medical School, Ann Arbor MI, USA
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Asghari Adib E, Shadrach JL, Reilly-Jankowiak L, Dwivedi MK, Rogers AE, Shahzad S, Passino R, Giger RJ, Pierchala BA, Collins CA. DLK signaling in axotomized neurons triggers complement activation and loss of upstream synapses. Cell Rep 2024; 43:113801. [PMID: 38363678 PMCID: PMC11088462 DOI: 10.1016/j.celrep.2024.113801] [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: 09/26/2022] [Revised: 12/27/2023] [Accepted: 01/31/2024] [Indexed: 02/18/2024] Open
Abstract
Axotomized spinal motoneurons (MNs) lose presynaptic inputs following peripheral nerve injury; however, the cellular mechanisms that lead to this form of synapse loss are currently unknown. Here, we delineate a critical role for neuronal kinase dual leucine zipper kinase (DLK)/MAP3K12, which becomes activated in axotomized neurons. Studies with conditional knockout mice indicate that DLK signaling activation in injured MNs triggers the induction of phagocytic microglia and synapse loss. Aspects of the DLK-regulated response include expression of C1q first from the axotomized MN and then later in surrounding microglia, which subsequently phagocytose presynaptic components of upstream synapses. Pharmacological ablation of microglia inhibits the loss of cholinergic C boutons from axotomized MNs. Together, the observations implicate a neuronal mechanism, governed by the DLK, in the induction of inflammation and the removal of synapses.
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Affiliation(s)
- Elham Asghari Adib
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Jennifer L Shadrach
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, USA
| | | | - Manish K Dwivedi
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA
| | - Abigail E Rogers
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Shameena Shahzad
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Ryan Passino
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Brian A Pierchala
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Catherine A Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Department of Neurosciences, Case Western Reserve University, Cleveland, OH, USA.
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Waller TJ, Collins CA. Opposing roles of Fos, Raw, and SARM1 in the regulation of axonal degeneration and synaptic structure. Front Cell Neurosci 2023; 17:1283995. [PMID: 38099151 PMCID: PMC10719852 DOI: 10.3389/fncel.2023.1283995] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 10/30/2023] [Indexed: 12/17/2023] Open
Abstract
Introduction The degeneration of injured axons is driven by conserved molecules, including the sterile armadillo TIR domain-containing protein SARM1, the cJun N-terminal kinase JNK, and regulators of these proteins. These molecules are also implicated in the regulation of synapse development though the mechanistic relationship of their functions in degeneration vs. development is poorly understood. Results and discussion Here, we uncover disparate functional relationships between SARM1 and the transmembrane protein Raw in the regulation of Wallerian degeneration and synaptic growth in motoneurons of Drosophila melanogaster. Our genetic data suggest that Raw antagonizes the downstream output MAP kinase signaling mediated by Drosophila SARM1 (dSarm). This relationship is revealed by dramatic synaptic overgrowth phenotypes at the larval neuromuscular junction when motoneurons are depleted for Raw or overexpress dSarm. While Raw antagonizes the downstream output of dSarm to regulate synaptic growth, it shows an opposite functional relationship with dSarm for axonal degeneration. Loss of Raw leads to decreased levels of dSarm in axons and delayed axonal degeneration that is rescued by overexpression of dSarm, supporting a model that Raw promotes the activation of dSarm in axons. However, inhibiting Fos also decreases dSarm levels in axons but has the opposite outcome of enabling Wallerian degeneration. The combined genetic data suggest that Raw, dSarm, and Fos influence each other's functions through multiple points of regulation to control the structure of synaptic terminals and the resilience of axons to degeneration.
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Affiliation(s)
- Thomas J. Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Catherine A. Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States
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Abstract
Axons are considered to be particularly vulnerable components of the nervous system; impairments to a neuron’s axon leads to an effective silencing of a neuron’s ability to communicate with other cells. Nervous systems have therefore evolved plasticity mechanisms for adapting to axonal damage. These include acute mechanisms that promote the degeneration and clearance of damaged axons and, in some cases, the initiation of new axonal growth and synapse formation to rebuild lost connections. Here we review how these diverse processes are influenced by the therapeutically targetable enzyme SARM1. SARM1 catalyzes the breakdown of NAD+, which, when unmitigated, can lead to rundown of this essential metabolite and axonal degeneration. SARM1’s enzymatic activity also triggers the activation of downstream signaling pathways, which manifest numerous functions for SARM1 in development, innate immunity and responses to injury. Here we will consider the multiple intersections between SARM1 and the injury signaling pathways that coordinate cellular adaptations to nervous system damage.
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Affiliation(s)
- Thomas J. Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Catherine A. Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States
- *Correspondence: Catherine A. Collins,
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McAfee K, Rosenow WT, Cherny S, Collins CA, Balmert LC, Webster G. Abnormal Microarray, Clinical Outcomes, and Surgical Risk Scores in Young Children with Cardiac Disease. Pediatr Cardiol 2021; 42:1785-1791. [PMID: 34160654 PMCID: PMC8557123 DOI: 10.1007/s00246-021-02664-4] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/14/2021] [Indexed: 11/26/2022]
Abstract
The clinical implications of abnormal chromosomal microarray (CMA) remain unclear for children less than 1 year of age with critical heart disease. Our objective was to determine whether abnormal CMA was related to surgical severity scores or to pre-determined clinical outcomes, including cardiac arrest. Retrospective review of children under 1 year of age admitted to a pediatric cardiac intensive care unit from December, 2014 to September, 2017. Associations between CMA result and cardiac arrest, syndromic abnormalities, and extracardiac anomalies were evaluated. A simple and multivariable logistic regression model was used to analyze associations between STAT mortality category and CMA result. The overall prevalence of abnormal microarray was 48/168 (29%), with peak prevalence in AV septal defects and left-sided obstructive lesions. There was no statistical association between surgical severity scores and abnormal CMA (STAT 1/2 vs. 3+, odds ratio 0.56, p = 0.196). Abnormal CMA was associated with a higher prevalence of cardiac arrest (5/48 abnormal CMA vs. 2/120 normal CMA, p = 0.02). Abnormal CMA was associated with a higher frequency of syndromic abnormalities (18/48 abnormal CMA vs. 13/120 normal CMA, p < 0.001). There was a high prevalence of abnormal CMA findings in the pediatric cardiac population less than 1 year of age (29%), associated with cardiac arrest, but not associated with surgical risk score. The absence of a standardized protocol for ordering a CMA in the setting of congenital heart disease results in a highly variable prevalence data.
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Affiliation(s)
- Kelsey McAfee
- Division of Cardiology, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, 225 East Chicago Avenue, Box 21, Chicago, IL, 60611, USA
| | - Will T Rosenow
- Department of Preventive Medicine (Biostatistics), Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Sara Cherny
- Division of Cardiology, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, 225 East Chicago Avenue, Box 21, Chicago, IL, 60611, USA
| | - Catherine A Collins
- Division of Cardiology, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, 225 East Chicago Avenue, Box 21, Chicago, IL, 60611, USA
| | - Lauren C Balmert
- Department of Preventive Medicine (Biostatistics), Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gregory Webster
- Division of Cardiology, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, 225 East Chicago Avenue, Box 21, Chicago, IL, 60611, USA.
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11
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Abstract
Axonal degeneration is controlled by the TIR domain NADase SARM1. In this issue of Neuron, Figley et al. (2021) reveal a key regulatory mechanism that controls SARM1's enzymatic activity, providing insight into how NAD+ biosynthesis by the NMNAT2 enzyme protects axons, and a new therapeutic path to tune SARM1 activity.
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Affiliation(s)
- Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1085, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1085, USA.
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12
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Hao Y, Waller TJ, Nye DM, Li J, Zhang Y, Hume RI, Rolls MM, Collins CA. Degeneration of Injured Axons and Dendrites Requires Restraint of a Protective JNK Signaling Pathway by the Transmembrane Protein Raw. J Neurosci 2019; 39:8457-8470. [PMID: 31492772 PMCID: PMC6807270 DOI: 10.1523/jneurosci.0016-19.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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: 01/03/2019] [Revised: 08/08/2019] [Accepted: 08/22/2019] [Indexed: 12/15/2022] Open
Abstract
The degeneration of injured axons involves a self-destruction pathway whose components and mechanism are not fully understood. Here, we report a new regulator of axonal resilience. The transmembrane protein Raw is cell autonomously required for the degeneration of injured axons, dendrites, and synapses in Drosophila melanogaster In both male and female raw hypomorphic mutant or knock-down larvae, the degeneration of injured axons, dendrites, and synapses from motoneurons and sensory neurons is strongly inhibited. This protection is insensitive to reduction in the levels of the NAD+ synthesis enzyme Nmnat (nicotinamide mononucleotide adenylyl transferase), but requires the c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinase and the transcription factors Fos and Jun (AP-1). Although these factors were previously known to function in axonal injury signaling and regeneration, Raw's function can be genetically separated from other axonal injury responses: Raw does not modulate JNK-dependent axonal injury signaling and regenerative responses, but instead restrains a protective pathway that inhibits the degeneration of axons, dendrites, and synapses. Although protection in raw mutants requires JNK, Fos, and Jun, JNK also promotes axonal degeneration. These findings suggest the existence of multiple independent pathways that share modulation by JNK, Fos, and Jun that influence how axons respond to stress and injury.SIGNIFICANCE STATEMENT Axonal degeneration is a major feature of neuropathies and nerve injuries and occurs via a cell autonomous self-destruction pathway whose mechanism is poorly understood. This study reports the identification of a new regulator of axonal degeneration: the transmembrane protein Raw. Raw regulates a cell autonomous nuclear signaling pathway whose yet unknown downstream effectors protect injured axons, dendrites, and synapses from degenerating. These findings imply that the susceptibility of axons to degeneration is strongly regulated in neurons. Future understanding of the cellular pathway regulated by Raw, which engages the c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinase and Fos and Jun transcription factors, may suggest new strategies to increase the resiliency of axons in debilitating neuropathies.
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Affiliation(s)
- Yan Hao
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1085
| | - Thomas J Waller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1085
| | - Derek M Nye
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, and
| | - Jiaxing Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1085
| | - Yanxiao Zhang
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109-2218
| | - Richard I Hume
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1085
| | - Melissa M Rolls
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, and
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1085,
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Asghari Adib E, Smithson LJ, Collins CA. An axonal stress response pathway: degenerative and regenerative signaling by DLK. Curr Opin Neurobiol 2018; 53:110-119. [PMID: 30053694 DOI: 10.1016/j.conb.2018.07.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/02/2018] [Indexed: 02/08/2023]
Abstract
Signaling through the dual leucine zipper-bearing kinase (DLK) is required for injured neurons to initiate new axonal growth; however, activation of this kinase also leads to neuronal degeneration and death in multiple models of injury and neurodegenerative diseases. This has spurred current consideration of DLK as a candidate therapeutic target, and raises a vital question: in what context is DLK a friend or foe to neurons? Here, we review our current understanding of DLK's function and mechanisms in regulating both regenerative and degenerative responses to axonal damage and stress in the nervous system.
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Affiliation(s)
- Elham Asghari Adib
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Laura J Smithson
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Catherine A Collins
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
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14
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Seong E, Insolera R, Dulovic M, Kamsteeg EJ, Trinh J, Brüggemann N, Sandford E, Li S, Ozel AB, Li JZ, Jewett T, Kievit AJA, Münchau A, Shakkottai V, Klein C, Collins CA, Lohmann K, van de Warrenburg BP, Burmeister M. Mutations in VPS13D lead to a new recessive ataxia with spasticity and mitochondrial defects. Ann Neurol 2018; 83:1075-1088. [PMID: 29604224 DOI: 10.1002/ana.25220] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 03/11/2018] [Accepted: 03/19/2018] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To identify novel causes of recessive ataxias, including spinocerebellar ataxia with saccadic intrusions, spastic ataxias, and spastic paraplegia. METHODS In an international collaboration, we independently performed exome sequencing in 7 families with recessive ataxia and/or spastic paraplegia. To evaluate the role of VPS13D mutations, we evaluated a Drosophila knockout model and investigated mitochondrial function in patient-derived fibroblast cultures. RESULTS Exome sequencing identified compound heterozygous mutations in VPS13D on chromosome 1p36 in all 7 families. This included a large family with 5 affected siblings with spinocerebellar ataxia with saccadic intrusions (SCASI), or spinocerebellar ataxia, recessive, type 4 (SCAR4). Linkage to chromosome 1p36 was found in this family with a logarithm of odds score of 3.1. The phenotypic spectrum in our 12 patients was broad. Although most presented with ataxia, additional or predominant spasticity was present in 5 patients. Disease onset ranged from infancy to 39 years, and symptoms were slowly progressive and included loss of independent ambulation in 5. All but 2 patients carried a loss-of-function (nonsense or splice site) mutation on one and a missense mutation on the other allele. Knockdown or removal of Vps13D in Drosophila neurons led to changes in mitochondrial morphology and impairment in mitochondrial distribution along axons. Patient fibroblasts showed altered morphology and functionality including reduced energy production. INTERPRETATION Our study demonstrates that compound heterozygous mutations in VPS13D cause movement disorders along the ataxia-spasticity spectrum, making VPS13D the fourth VPS13 paralog involved in neurological disorders. Ann Neurol 2018.
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Affiliation(s)
- Eunju Seong
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - Ryan Insolera
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Marija Dulovic
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Joanne Trinh
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | | | - Erin Sandford
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - Sheng Li
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI
| | - Ayse Bilge Ozel
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Jun Z Li
- Department of Human Genetics, University of Michigan, Ann Arbor, MI.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI
| | - Tamison Jewett
- Department of Pediatrics, Section on Medical Genetics, Wake Forest School of Medicine, Winston-Salem, NC
| | - Anneke J A Kievit
- Department of Clinical Genetics, Erasmus MC, Rotterdam, the Netherlands
| | | | - Vikram Shakkottai
- Departments of Neurology and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
| | - Christine Klein
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Bart P van de Warrenburg
- Department of Neurology, Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Margit Burmeister
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI.,Department of Human Genetics, University of Michigan, Ann Arbor, MI.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI.,Department of Psychiatry, University of Michigan, Ann Arbor, MI
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15
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Li J, Zhang YV, Asghari Adib E, Stanchev DT, Xiong X, Klinedinst S, Soppina P, Jahn TR, Hume RI, Rasse TM, Collins CA. Restraint of presynaptic protein levels by Wnd/DLK signaling mediates synaptic defects associated with the kinesin-3 motor Unc-104. eLife 2017; 6. [PMID: 28925357 PMCID: PMC5605197 DOI: 10.7554/elife.24271] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 12/15/2016] [Accepted: 08/11/2017] [Indexed: 12/19/2022] Open
Abstract
The kinesin-3 family member Unc-104/KIF1A is required for axonal transport of many presynaptic components to synapses, and mutation of this gene results in synaptic dysfunction in mice, flies and worms. Our studies at the Drosophila neuromuscular junction indicate that many synaptic defects in unc-104-null mutants are mediated independently of Unc-104's transport function, via the Wallenda (Wnd)/DLK MAP kinase axonal damage signaling pathway. Wnd signaling becomes activated when Unc-104's function is disrupted, and leads to impairment of synaptic structure and function by restraining the expression level of active zone (AZ) and synaptic vesicle (SV) components. This action concomitantly suppresses the buildup of synaptic proteins in neuronal cell bodies, hence may play an adaptive role to stresses that impair axonal transport. Wnd signaling also becomes activated when pre-synaptic proteins are over-expressed, suggesting the existence of a feedback circuit to match synaptic protein levels to the transport capacity of the axon.
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Affiliation(s)
- Jiaxing Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Yao V Zhang
- Junior Research Group Synaptic Plasticity, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Graduate School of Cellular and Molecular Neuroscience, University of Tübingen, Tübingen, Germany
| | - Elham Asghari Adib
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Doychin T Stanchev
- Junior Research Group Synaptic Plasticity, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Graduate School of Cellular and Molecular Neuroscience, University of Tübingen, Tübingen, Germany
| | - Xin Xiong
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Susan Klinedinst
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Pushpanjali Soppina
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Thomas Robert Jahn
- CHS Research Group Proteostasis in Neurodegenerative Disease, DKFZ Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Richard I Hume
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Tobias M Rasse
- Junior Research Group Synaptic Plasticity, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,CHS Research Group Proteostasis in Neurodegenerative Disease, DKFZ Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, United States
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16
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Chen L, Nye DM, Stone MC, Weiner AT, Gheres KW, Xiong X, Collins CA, Rolls MM. Mitochondria and Caspases Tune Nmnat-Mediated Stabilization to Promote Axon Regeneration. PLoS Genet 2016; 12:e1006503. [PMID: 27923046 PMCID: PMC5173288 DOI: 10.1371/journal.pgen.1006503] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [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: 01/18/2016] [Revised: 12/20/2016] [Accepted: 11/22/2016] [Indexed: 11/24/2022] Open
Abstract
Axon injury can lead to several cell survival responses including increased stability and axon regeneration. Using an accessible Drosophila model system, we investigated the regulation of injury responses and their relationship. Axon injury stabilizes the rest of the cell, including the entire dendrite arbor. After axon injury we found mitochondrial fission in dendrites was upregulated, and that reducing fission increased stabilization or neuroprotection (NP). Thus axon injury seems to both turn on NP, but also dampen it by activating mitochondrial fission. We also identified caspases as negative regulators of axon injury-mediated NP, so mitochondrial fission could control NP through caspase activation. In addition to negative regulators of NP, we found that nicotinamide mononucleotide adenylyltransferase (Nmnat) is absolutely required for this type of NP. Increased microtubule dynamics, which has previously been associated with NP, required Nmnat. Indeed Nmnat overexpression was sufficient to induce NP and increase microtubule dynamics in the absence of axon injury. DLK, JNK and fos were also required for NP. Because NP occurs before axon regeneration, and NP seems to be actively downregulated, we tested whether excessive NP might inhibit regeneration. Indeed both Nmnat overexpression and caspase reduction reduced regeneration. In addition, overexpression of fos or JNK extended the timecourse of NP and dampened regeneration in a Nmnat-dependent manner. These data suggest that NP and regeneration are conflicting responses to axon injury, and that therapeutic strategies that boost NP may reduce regeneration. Unlike many other cell types, most neurons last a lifetime. When injured, these cells often activate survival and repair strategies rather than dying. One such response is regeneration of the axon after it is injured. Axon regeneration is a conserved process activated by the same signaling cascade in worms, flies and mammals. Surprisingly we find that this signaling cascade first initiates a different response. This first response stabilizes the cell, and its downregulation by mitochondrial fission and caspases allows for maximum regeneration at later times. We propose that neurons respond to axon injury in a multi-step process with an early lock-down phase in which the cell is stabilized, followed by a more plastic state in which regeneration is maximized.
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Affiliation(s)
- Li Chen
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Derek M. Nye
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Michelle C. Stone
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alexis T. Weiner
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kyle W. Gheres
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Xin Xiong
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Melissa M. Rolls
- Huck Institutes of the Life Sciences, and Biochemistry and Molecular Biology,The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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17
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Wong CO, Palmieri M, Li J, Akhmedov D, Chao Y, Broadhead GT, Zhu MX, Berdeaux R, Collins CA, Sardiello M, Venkatachalam K. Diminished MTORC1-Dependent JNK Activation Underlies the Neurodevelopmental Defects Associated with Lysosomal Dysfunction. Cell Rep 2015; 12:2009-20. [PMID: 26387958 DOI: 10.1016/j.celrep.2015.08.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/20/2015] [Accepted: 08/14/2015] [Indexed: 12/12/2022] Open
Abstract
Here, we evaluate the mechanisms underlying the neurodevelopmental deficits in Drosophila and mouse models of lysosomal storage diseases (LSDs). We find that lysosomes promote the growth of neuromuscular junctions (NMJs) via Rag GTPases and mechanistic target of rapamycin complex 1 (MTORC1). However, rather than employing S6K/4E-BP1, MTORC1 stimulates NMJ growth via JNK, a determinant of axonal growth in Drosophila and mammals. This role of lysosomal function in regulating JNK phosphorylation is conserved in mammals. Despite requiring the amino-acid-responsive kinase MTORC1, NMJ development is insensitive to dietary protein. We attribute this paradox to anaplastic lymphoma kinase (ALK), which restricts neuronal amino acid uptake, and the administration of an ALK inhibitor couples NMJ development to dietary protein. Our findings provide an explanation for the neurodevelopmental deficits in LSDs and suggest an actionable target for treatment.
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Affiliation(s)
- Ching-On Wong
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Michela Palmieri
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, TX 77030, USA
| | - Jiaxing Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dmitry Akhmedov
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Yufang Chao
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Geoffrey T Broadhead
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA; Program in Cell and Regulatory Biology (CRB), Graduate School of Biomedical Sciences, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA; Program in Cell and Regulatory Biology (CRB), Graduate School of Biomedical Sciences, University of Texas School of Medicine, Houston, TX 77030, USA
| | - Catherine A Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Marco Sardiello
- Department of Molecular and Human Genetics, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, TX 77030, USA
| | - Kartik Venkatachalam
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, TX 77030, USA; Program in Cell and Regulatory Biology (CRB), Graduate School of Biomedical Sciences, University of Texas School of Medicine, Houston, TX 77030, USA; Program in Neuroscience, Graduate School of Biomedical Sciences, University of Texas School of Medicine, Houston, TX 77030, USA.
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18
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Siebert M, Böhme MA, Driller JH, Babikir H, Mampell MM, Rey U, Ramesh N, Matkovic T, Holton N, Reddy-Alla S, Göttfert F, Kamin D, Quentin C, Klinedinst S, Andlauer TF, Hell SW, Collins CA, Wahl MC, Loll B, Sigrist SJ. A high affinity RIM-binding protein/Aplip1 interaction prevents the formation of ectopic axonal active zones. eLife 2015; 4. [PMID: 26274777 PMCID: PMC4536467 DOI: 10.7554/elife.06935] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [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: 02/09/2015] [Accepted: 07/24/2015] [Indexed: 12/17/2022] Open
Abstract
Synaptic vesicles (SVs) fuse at active zones (AZs) covered by a protein scaffold, at Drosophila synapses comprised of ELKS family member Bruchpilot (BRP) and RIM-binding protein (RBP). We here demonstrate axonal co-transport of BRP and RBP using intravital live imaging, with both proteins co-accumulating in axonal aggregates of several transport mutants. RBP, via its C-terminal Src-homology 3 (SH3) domains, binds Aplip1/JIP1, a transport adaptor involved in kinesin-dependent SV transport. We show in atomic detail that RBP C-terminal SH3 domains bind a proline-rich (PxxP) motif of Aplip1/JIP1 with submicromolar affinity. Pointmutating this PxxP motif provoked formation of ectopic AZ-like structures at axonal membranes. Direct interactions between AZ proteins and transport adaptors seem to provide complex avidity and shield synaptic interaction surfaces of pre-assembled scaffold protein transport complexes, thus, favouring physiological synaptic AZ assembly over premature assembly at axonal membranes. DOI:http://dx.doi.org/10.7554/eLife.06935.001 To pass on information, the neurons that make up the nervous system connect at structures known as synapses. Chemical messengers called neurotransmitters are released from one neuron, and travel across the synapse to trigger a response in the neighbouring cell. The formation of new synapses plays an important role in learning and memory, but many aspects of this process are not well understood. In a specific region of the synapse called the active zone, a scaffold of proteins helps to release the neurotransmitters. These proteins are made in the cell body of the neuron, and are then transported to the end of the long, thin axons that protrude from the cell body. This presents a challenge for the cell, because the components of the active zone scaffold must be correctly targeted to the synapse at the end of the axon, ensuring the active zone scaffold assembles only at its proper location. Siebert, Böhme et al. studied how some of the proteins that are found in the active zone scaffold of the fruit fly Drosophila are transported along axons. Labelling the proteins with fluorescent markers allowed their movement to be examined under a microscope in living Drosophila larvae. The results showed that two of the proteins—known as BRP and RBP—are transported along the axons together. Further investigation revealed that a transport adaptor protein called Aplip1, which binds to RBP, is required for this movement. Siebert, Böhme et al. established the structure of the part of RBP where this interaction occurs, and found that mutating this region causes premature active zone scaffold assembly in the axonal part of the neuron. The interaction between RBP and Aplip1 is very strong, and this helps to prevent the scaffold assembling before it has reached the correct part of the neuron. Exactly how the transport adaptor and active zone protein are separated once they reach their final destination (the synapse) remains to be discovered. DOI:http://dx.doi.org/10.7554/eLife.06935.002
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Affiliation(s)
- Matthias Siebert
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Mathias A Böhme
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Jan H Driller
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Husam Babikir
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Malou M Mampell
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Ulises Rey
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Niraja Ramesh
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Tanja Matkovic
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Nicole Holton
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Suneel Reddy-Alla
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Fabian Göttfert
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Dirk Kamin
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christine Quentin
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Susan Klinedinst
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Till Fm Andlauer
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Stefan W Hell
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Catherine A Collins
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Markus C Wahl
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Bernhard Loll
- Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Stephan J Sigrist
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
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19
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Mishra B, Ghannad-Rezaie M, Li J, Wang X, Hao Y, Ye B, Chronis N, Collins CA. Using microfluidics chips for live imaging and study of injury responses in Drosophila larvae. J Vis Exp 2014:e50998. [PMID: 24562098 PMCID: PMC4117361 DOI: 10.3791/50998] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Live imaging is an important technique for studying cell biological processes, however this can be challenging in live animals. The translucent cuticle of the Drosophila larva makes it an attractive model organism for live imaging studies. However, an important challenge for live imaging techniques is to noninvasively immobilize and position an animal on the microscope. This protocol presents a simple and easy to use method for immobilizing and imaging Drosophila larvae on a polydimethylsiloxane (PDMS) microfluidic device, which we call the 'larva chip'. The larva chip is comprised of a snug-fitting PDMS microchamber that is attached to a thin glass coverslip, which, upon application of a vacuum via a syringe, immobilizes the animal and brings ventral structures such as the nerve cord, segmental nerves, and body wall muscles, within close proximity to the coverslip. This allows for high-resolution imaging, and importantly, avoids the use of anesthetics and chemicals, which facilitates the study of a broad range of physiological processes. Since larvae recover easily from the immobilization, they can be readily subjected to multiple imaging sessions. This allows for longitudinal studies over time courses ranging from hours to days. This protocol describes step-by-step how to prepare the chip and how to utilize the chip for live imaging of neuronal events in 3rd instar larvae. These events include the rapid transport of organelles in axons, calcium responses to injury, and time-lapse studies of the trafficking of photo-convertible proteins over long distances and time scales. Another application of the chip is to study regenerative and degenerative responses to axonal injury, so the second part of this protocol describes a new and simple procedure for injuring axons within peripheral nerves by a segmental nerve crush.
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Affiliation(s)
- Bibhudatta Mishra
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
| | | | - Jiaxing Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
| | - Xin Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
| | - Yan Hao
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
| | - Bing Ye
- Life Sciences Institute, University of Michigan; Department of Cell and Developmental Biology, University of Michigan
| | - Nikos Chronis
- Department of Biomedical Engineering, University of Michigan; Department of Mechanical Engineering, University of Michigan
| | - Catherine A Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan;
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20
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Wang X, Kim JH, Bazzi M, Robinson S, Collins CA, Ye B. Bimodal control of dendritic and axonal growth by the dual leucine zipper kinase pathway. PLoS Biol 2013; 11:e1001572. [PMID: 23750116 PMCID: PMC3672216 DOI: 10.1371/journal.pbio.1001572] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [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: 12/19/2012] [Accepted: 04/16/2013] [Indexed: 02/03/2023] Open
Abstract
Knowledge of the molecular and genetic mechanisms underlying the separation of dendritic and axonal compartments is not only crucial for understanding the assembly of neural circuits, but also for developing strategies to correct defective dendrites or axons in diseases with subcellular precision. Previous studies have uncovered regulators dedicated to either dendritic or axonal growth. Here we investigate a novel regulatory mechanism that differentially directs dendritic and axonal growth within the same neuron in vivo. We find that the dual leucine zipper kinase (DLK) signaling pathway in Drosophila, which consists of Highwire and Wallenda and controls axonal growth, regeneration, and degeneration, is also involved in dendritic growth in vivo. Highwire, an evolutionarily conserved E3 ubiquitin ligase, restrains axonal growth but acts as a positive regulator for dendritic growth in class IV dendritic arborization neurons in the larva. While both the axonal and dendritic functions of highwire require the DLK kinase Wallenda, these two functions diverge through two downstream transcription factors, Fos and Knot, which mediate the axonal and dendritic regulation, respectively. This study not only reveals a previously unknown function of the conserved DLK pathway in controlling dendrite development, but also provides a novel paradigm for understanding how neuronal compartmentalization and the diversity of neuronal morphology are achieved.
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Affiliation(s)
- Xin Wang
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jung Hwan Kim
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mouna Bazzi
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara Robinson
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bing Ye
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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21
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Xiong X, Hao Y, Sun K, Li J, Li X, Mishra B, Soppina P, Wu C, Hume RI, Collins CA. The Highwire ubiquitin ligase promotes axonal degeneration by tuning levels of Nmnat protein. PLoS Biol 2012; 10:e1001440. [PMID: 23226106 PMCID: PMC3514318 DOI: 10.1371/journal.pbio.1001440] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [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: 05/22/2012] [Accepted: 10/24/2012] [Indexed: 11/18/2022] Open
Abstract
Highwire, a conserved axonal E3 ubiquitin ligase, regulates the initiation of axonal degeneration after injury in Drosophila by regulating the levels of the NAD+ biosynthetic enzyme, Nmnat, and the Wnd kinase. Axonal degeneration is a hallmark of many neuropathies, neurodegenerative diseases, and injuries. Here, using a Drosophila injury model, we have identified a highly conserved E3 ubiquitin ligase, Highwire (Hiw), as an important regulator of axonal and synaptic degeneration. Mutations in hiw strongly inhibit Wallerian degeneration in multiple neuron types and developmental stages. This new phenotype is mediated by a new downstream target of Hiw: the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat), which acts in parallel to a previously known target of Hiw, the Wallenda dileucine zipper kinase (Wnd/DLK) MAPKKK. Hiw promotes a rapid disappearance of Nmnat protein in the distal stump after injury. An increased level of Nmnat protein in hiw mutants is both required and sufficient to inhibit degeneration. Ectopically expressed mouse Nmnat2 is also subject to regulation by Hiw in distal axons and synapses. These findings implicate an important role for endogenous Nmnat and its regulation, via a conserved mechanism, in the initiation of axonal degeneration. Through independent regulation of Wnd/DLK, whose function is required for proximal axons to regenerate, Hiw plays a central role in coordinating both regenerative and degenerative responses to axonal injury. Axons degenerate after injury and during neurodegenerative diseases, but we are still searching for the cellular mechanism responsible for this degeneration. Here, using a nerve crush injury assay in the fruit fly Drosophila, we have identified a role for a conserved molecule named Highwire (Hiw) in the initiation of axonal degeneration. Hiw is an E3 ubiquitin ligase thought to regulate the levels of specific downstream proteins by targeting their destruction. We show that Hiw promotes axonal degeneration by regulating two independent downstream targets: the Wallenda (Wnd) kinase, and the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat). Interestingly, Nmnat has previously been implicated in a protective role in neurons. Our findings indicate that Nmnat protein is down-regulated in axons by Hiw and that this regulation plays a critical role in the degeneration of axons and synapses. The other target, the Wnd kinase, was previously known for its role in promoting new axonal growth after injury. We propose that Hiw coordinates multiple responses to regenerate damaged neuronal circuits after injury: degeneration of the distal axon via Nmnat, and new growth of the proximal axon via Wnd.
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Affiliation(s)
- Xin Xiong
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Yan Hao
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kan Sun
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jiaxing Li
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Xia Li
- Neuroscience Center for Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Bibhudatta Mishra
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Pushpanjali Soppina
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Chunlai Wu
- Neuroscience Center for Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Richard I. Hume
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Xiong X, Wang X, Ewanek R, Bhat P, Diantonio A, Collins CA. Protein turnover of the Wallenda/DLK kinase regulates a retrograde response to axonal injury. ACTA ACUST UNITED AC 2010; 191:211-23. [PMID: 20921142 PMCID: PMC2953441 DOI: 10.1083/jcb.201006039] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regenerative responses to axonal injury involve changes in gene expression; however, little is known about how such changes can be induced from a distant site of injury. In this study, we describe a nerve crush assay in Drosophila melanogaster to study injury signaling and regeneration mechanisms. We find that Wallenda (Wnd), a conserved mitogen-activated protein kinase (MAPK) kinase kinase homologous to dual leucine zipper kinase, functions as an upstream mediator of a cell-autonomous injury signaling cascade that involves the c-Jun NH(2)-terminal kinase MAPK and Fos transcription factor. Wnd is physically transported in axons, and axonal transport is required for the injury signaling mechanism. Wnd is regulated by a conserved E3 ubiquitin ligase, named Highwire (Hiw) in Drosophila. Injury induces a rapid increase in Wnd protein concomitantly with a decrease in Hiw protein. In hiw mutants, injury signaling is constitutively active, and neurons initiate a faster regenerative response. Our data suggest that the regulation of Wnd protein turnover by Hiw can function as a damage surveillance mechanism for responding to axonal injury.
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Affiliation(s)
- Xin Xiong
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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Watt FM, Collins CA. Role of beta-catenin in epidermal stem cell expansion, lineage selection, and cancer. Cold Spring Harb Symp Quant Biol 2008; 73:503-12. [PMID: 19022747 DOI: 10.1101/sqb.2008.73.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The mammalian epidermis is an excellent model with which to analyze the factors that regulate adult stem cell renewal, lineage selection, and tumor formation. One of the key regulators of all three processes is beta-catenin, the main cytoplasmic effector of the canonical Wnt signaling pathway. In this chapter, we review some of the ways in which beta-catenin exerts its effects on cultured human epidermal cells and in genetically modified mice. We highlight the importance of the timing and level of activation and discuss some of the pathways activated downstream from beta-catenin. Finally, we demonstrate the importance of Lef/Tcf-independent beta-catenin signaling through interaction with the vitamin D receptor.
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Affiliation(s)
- F M Watt
- Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Cambridge CB2 1QR, United Kingdom
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Daniels RW, Gelfand MV, Collins CA, DiAntonio A. Visualizing glutamatergic cell bodies and synapses in Drosophila larval and adult CNS. J Comp Neurol 2008; 508:131-52. [PMID: 18302156 DOI: 10.1002/cne.21670] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the vertebrate central nervous system (CNS) and at Drosophila neuromuscular junctions (NMJs). Although glutamate is also used as a transmitter in the Drosophila CNS, there has been no systematic description of the central glutamatergic signaling system in the fly. With the recent cloning of the Drosophila vesicular glutamate transporter (DVGLUT), it is now possible to mark many, if not all, central glutamatergic neurons and synapses. Here we present the pattern of glutamatergic synapses and cell bodies in the late larval CNS and in the adult fly brain by using an anti-DVGLUT antibody. We also introduce two new tools for studying the Drosophila glutamatergic system: a dvglut promoter fragment fused to Gal4 whose expression labels glutamatergic neurons and a green fluorescent protein (GFP)-tagged DVGLUT transgene that localizes to synapses. In the larval CNS, we find synaptic DVGLUT immunoreactivity prominent in all brain lobe neuropil compartments except for the mushroom body. Likewise in the adult CNS, glutamatergic synapses are abundant throughout all major brain structures except the mushroom body. We also find that the larval ventral nerve cord neuropil is rich in glutamatergic synapses, which are primarily located near the dorsal surface of the neuropil, segregated from the ventrally positioned cholinergic processes. This description of the glutamatergic system in Drosophila highlights the prevalence of glutamatergic neurons in the CNS and presents tools for future study and manipulation of glutamatergic transmission.
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Affiliation(s)
- Richard W Daniels
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Horiuchi D, Collins CA, Bhat P, Barkus RV, DiAntonio A, Saxton WM. Control of a kinesin-cargo linkage mechanism by JNK pathway kinases. Curr Biol 2007; 17:1313-7. [PMID: 17658258 PMCID: PMC2041807 DOI: 10.1016/j.cub.2007.06.062] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 06/19/2007] [Accepted: 06/20/2007] [Indexed: 10/23/2022]
Abstract
Long-distance organelle transport toward axon terminals, critical for neuron development and function, is driven along microtubules by kinesins [1, 2]. The biophysics of force production by various kinesins is known in detail. However, the mechanisms of in vivo transport processes are poorly understood because little is known about how motor-cargo linkages are controlled. A c-Jun N-terminal kinase (JNK)-interacting protein (JIP1) has been identified previously as a linker between kinesin-1 and certain vesicle membrane proteins, such as Alzheimer's APP protein and a reelin receptor ApoER2 [3, 4]. JIPs are also known to be scaffolding proteins for JNK pathway kinases [5, 6]. Here, we report evidence that a Drosophila ubiquitin-specific hydrolase and a JNK signaling pathway that it modulates can regulate a JIP1-kinesin linkage. The JNK pathway includes a MAPKKK (Wallenda/DLK), a MAPKK (Hemipterous/MKK7), and the Drosophila JNK homolog Basket. Genetic tests indicate that those kinases are required for normal axonal transport. Biochemical tests show that activation of Wallenda (DLK) and Hemipterous (MKK7) disrupts binding between kinesin-1 and APLIP1, which is the Drosophila JIP1 homolog. This suggests a control mechanism in which an activated JNK pathway influences axonal transport by functioning as a kinesin-cargo dissociation factor.
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Affiliation(s)
- Dai Horiuchi
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Catherine A. Collins
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Pavan Bhat
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | | | - Aaron DiAntonio
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - William M. Saxton
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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Abstract
In Drosophila, the larval neuromuscular junction is particularly tractable for studying how synapses develop and function. In contrast to vertebrate central synapses, each presynaptic motor neuron and postsynaptic muscle cell is unique and identifiable, and the wiring circuit is invariant. Thus, the full power of Drosophila genetics can be brought to bear on a single, reproducibly identifiable, synaptic terminal. Each individual neuromuscular junction encompasses hundreds of synaptic neurotransmitter release sites housed in a chain of synaptic boutons. Recent advances have increased our understanding of the mechanisms that shape the development of both individual synapses--that is, the transmitter release sites including active zones and their apposed glutamate receptor clusters--and the whole synaptic terminal that connects a pre- and post-synaptic cell.
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Affiliation(s)
- Catherine A Collins
- Department of Molecular Biology and Pharmacology, Campus Box 8103, 660 South Euclid, Washington University School of Medicine, St Louis, MO 63110, USA
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Collins CA, Wairkar YP, Johnson SL, DiAntonio A. Highwire restrains synaptic growth by attenuating a MAP kinase signal. Neuron 2006; 51:57-69. [PMID: 16815332 DOI: 10.1016/j.neuron.2006.05.026] [Citation(s) in RCA: 270] [Impact Index Per Article: 15.0] [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] [Received: 01/11/2006] [Revised: 04/25/2006] [Accepted: 05/30/2006] [Indexed: 11/23/2022]
Abstract
Highwire is an extremely large, evolutionarily conserved E3 ubiquitin ligase that negatively regulates synaptic growth at the Drosophila NMJ. Highwire has been proposed to restrain synaptic growth by downregulating a synaptogenic signal. Here we identify such a downstream signaling pathway. A screen for suppressors of the highwire synaptic overgrowth phenotype yielded mutations in wallenda, a MAP kinase kinase kinase (MAPKKK) homologous to vertebrate DLK and LZK. wallenda is both necessary for highwire synaptic overgrowth and sufficient to promote synaptic overgrowth, and synaptic levels of Wallenda protein are controlled by Highwire and ubiquitin hydrolases. highwire synaptic overgrowth requires the MAP kinase JNK and the transcription factor Fos. These results suggest that Highwire controls structural plasticity of the synapse by regulating gene expression through a MAP kinase signaling pathway. In addition to controlling synaptic growth, Highwire promotes synaptic function through a separate pathway that does not require wallenda.
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Affiliation(s)
- Catherine A Collins
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, Washington University, St. Louis, Missouri 63110, USA
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Abstract
Highwire is a huge, evolutionarily conserved protein that is required to restrain synaptic growth and promote synaptic transmission at the Drosophila neuromuscular junction. Current models of highwire function suggest that it may act as a ubiquitin ligase to regulate synaptic development. However, it is not known in which cells highwire functions, whether its putative ligase domain is required for function, or whether highwire regulates the synapse during development or alternatively sets cell fate in the embryo. We performed a series of transgenic rescue experiments to test the spatial, structural, and temporal requirements for highwire function. We find that presynaptic activity of highwire is both necessary and sufficient to regulate both synapse morphology and physiology. The Highwire RING domain, which is postulated to function as an E3 ubiquitin ligase, is required for highwire function. In addition, highwire acts throughout larval development to regulate synaptic morphology and function. Finally, we show that the morphological and physiological phenotypes of highwire mutants have different dosage and temporal requirements for highwire, demonstrating that highwire may independently regulate the molecular pathways controlling synaptic growth and function.
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Affiliation(s)
- Chunlai Wu
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Daniels RW, Collins CA, Chen K, Gelfand MV, Featherstone DE, DiAntonio A. A single vesicular glutamate transporter is sufficient to fill a synaptic vesicle. Neuron 2006; 49:11-6. [PMID: 16387635 PMCID: PMC2248602 DOI: 10.1016/j.neuron.2005.11.032] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [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] [Received: 07/25/2005] [Revised: 10/20/2005] [Accepted: 11/17/2005] [Indexed: 11/17/2022]
Abstract
Quantal size is the postsynaptic response to the release of a single synaptic vesicle and is determined in part by the amount of transmitter within that vesicle. At glutamatergic synapses, the vesicular glutamate transporter (VGLUT) fills vesicles with glutamate. While elevated VGLUT expression increases quantal size, the minimum number of transporters required to fill a vesicle is unknown. In Drosophila DVGLUT mutants, reduced transporter levels lead to a dose-dependent reduction in the frequency of spontaneous quantal release with no change in quantal size. Quantal frequency is not limited by vesicle number or impaired exocytosis. This suggests that a single functional unit of transporter is both necessary and sufficient to fill a vesicle to completion and that vesicles without DVGLUT are empty. Consistent with the presence of empty vesicles, at dvglut mutant synapses synaptic vesicles are smaller, suggesting that vesicle filling and/or transporter level is an important determinant of vesicle size.
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Affiliation(s)
- Richard W. Daniels
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Catherine A. Collins
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Kaiyun Chen
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Maria V. Gelfand
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - David E. Featherstone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Aaron DiAntonio
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
- Correspondence:
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Daniels RW, Collins CA, Gelfand MV, Dant J, Brooks ES, Krantz DE, DiAntonio A. Increased expression of the Drosophila vesicular glutamate transporter leads to excess glutamate release and a compensatory decrease in quantal content. J Neurosci 2005; 24:10466-74. [PMID: 15548661 PMCID: PMC6730318 DOI: 10.1523/jneurosci.3001-04.2004] [Citation(s) in RCA: 267] [Impact Index Per Article: 14.1] [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: 11/21/2022] Open
Abstract
Quantal size is a fundamental parameter controlling the strength of synaptic transmission. The transmitter content of synaptic vesicles is one mechanism that can affect the physiological response to the release of a single vesicle. At glutamatergic synapses, vesicular glutamate transporters (VGLUTs) are responsible for filling synaptic vesicles with glutamate. To investigate how VGLUT expression can regulate synaptic strength in vivo, we have identified the Drosophila vesicular glutamate transporter, which we name DVGLUT. DVGLUT mRNA is expressed in glutamatergic motoneurons and a large number of interneurons in the Drosophila CNS. DVGLUT protein resides on synaptic vesicles and localizes to the presynaptic terminals of all known glutamatergic neuromuscular junctions as well as to synapses throughout the CNS neuropil. Increasing the expression of DVGLUT in motoneurons leads to an increase in quantal size that is accompanied by an increase in synaptic vesicle volume. At synapses confronted with increased glutamate release from each vesicle, there is a compensatory decrease in the number of synaptic vesicles released that maintains normal levels of synaptic excitation. These results demonstrate that (1) expression of DVGLUT determines the size and glutamate content of synaptic vesicles and (2) homeostatic mechanisms exist to attenuate the excitatory effects of excess glutamate release.
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Affiliation(s)
- Richard W Daniels
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Ahmed I, Collins CA, Lewis MP, Olsen I, Knowles JC. Processing, characterisation and biocompatibility of iron-phosphate glass fibres for tissue engineering. Biomaterials 2004; 25:3223-32. [PMID: 14980417 DOI: 10.1016/j.biomaterials.2003.10.013] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [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: 07/29/2003] [Accepted: 09/29/2003] [Indexed: 11/16/2022]
Abstract
Iron-phosphate glass fibres based on the CaO-Na2O-Fe2O3-P2O5 system have been processed and characterised via thermal, XRPD, dissolution rates, diameter and biocompatibility studies. The compositions investigated were fixed at 50mol% P2O5, and the CaO content was varied between 30, 35 and 40mol%. The Fe2O3 was added in low amounts from 1-5mol%, substituting it for the Na2O mol%. The number of Tc (crystallisation temperature) peaks detected from the thermal analysis traces only showed correlation with XRPD analysis, for five out of the 15 compositions investigated. It has been suggested that either the crystalline phases had very similar Tc temperatures or that the other phase(s) were present in very small quantities. There was a good match seen with number of Tm (melting temperature) peaks picked up from the DTA traces, with the number of phases identified from XRPD analysis. The main phases identified from XRPD were NaCa(PO3)3, CaP2O6 and NaFeP2O7. Using network connectivity (NC), predictions on Qn species present within the compositions investigated were made. The predicted species (metaphosphates) matched with phases identified from XRPD analysis. A decrease in dissolution rates for the bulk glass and glass fibres was seen with an increase in CaO mol%, along with an increase in Fe2O3 mol%. An increase in fibre dissolution rates was seen with a decrease in diameter size. The biocompatibility studies were conducted using a conditionally immortal muscle precursor cell line derived from the H-2Kb-tsA58 immortomouse. It was found that iron-phosphate glass fibres containing 4-5mol% Fe2O3 was sufficient for cell attachment and differentiation. It was seen that myotubes formed along the axis of the fibres (which was indicative of differentiation). The biocompatibility of these compositions was attributed to the enhanced chemical durability of the glass fibres.
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Affiliation(s)
- I Ahmed
- Eastman Dental Institute, Division of Biomaterials and Tissue Engineering, University College London, 256 Gray's Inn Road, London WC1X 8LD, UK
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Abstract
The function and regulation of actin-cytoskeletal dynamics during synaptic growth is poorly understood. In this issue of Neuron, Coyle et al. report the identification of nervous wreck (nwk), a synapse-specific adaptor molecule in Drosophila that regulates synaptic growth and morphology via Wasp, a well-characterized mediator of actin dynamics.
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Affiliation(s)
- Catherine A Collins
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Abstract
Duchenne's muscular dystrophy (DMD) is a lethal childhood disease caused by mutations of the dystrophin gene, the protein product of which, dystrophin, has a vital role in maintaining muscle structure and function. Homologues of DMD have been identified in several animals including dogs, cats, mice, fish and invertebrates. The most notable of these are the extensively studied mdx mouse, a genetic and biochemical model of the human disease, and the muscular dystrophic Golden Retriever dog, which is the nearest pathological counterpart of DMD. These models have been used to explore potential therapeutic approaches along a number of avenues including gene replacement and cell transplantation strategies. High-throughput screening of pharmacological and genetic therapies could potentially be carried out in recently available smaller models such as zebrafish and Caenorhabditis elegans. It is possible that a successful treatment will eventually be identified through the integration of studies in multiple species differentially suited to addressing particular questions.
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Affiliation(s)
- C A Collins
- Muscle Cell Biology Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Hospital, London, UK.
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Laven RA, Biggadike HJ, Collins CA. The Effect of Increasing Urea Intake in the Lactating Dairy Cow on Follicular Dynamics and Ovulation. Acta Vet Scand 2003. [DOI: 10.1186/1751-0147-44-s1-p106] [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: 11/10/2022] Open
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Collins CA, Guthrie C. Genetic interactions between the 5' and 3' splice site consensus sequences and U6 snRNA during the second catalytic step of pre-mRNA splicing. RNA 2001; 7:1845-1854. [PMID: 11780639 PMCID: PMC1370222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The YAG/ consensus sequence at the 3' end of introns (the slash indicates the location of the 3' splice site) is essential for catalysis of the second step of pre-mRNA splicing. Little is known about the interactions formed by these three nucleotides in the spliceosome. Although previous observations have suggested that the G of the YAG/ interacts with the first nucleotide of the /GUA consensus sequence at the 5' end of the intron, additional interactions have not been identified. Here we report several striking genetic interactions between A+3 of the 5' /GUA with Y-3 of the 3' YAG/ and G50 of the highly conserved ACAGAG motif in U6 snRNA. Two mutations in U6 G50 of the ACAGAG can weakly suppress two mutations in A+3 of the 5' /GUA. This suppression is significantly enhanced upon the inclusion of a specific mutation Y-3 in the 3' YAG/. RNA analysis confirmed that the severe splicing defect observed in A+3 and Y-3 double mutants can be rescued to near wild-type levels by the mutations in U6 G50. The contributions of each mutation to the genetic interaction and the strong position specificity of suppression, combined with previous findings, support a model in which the 5' /GUA and the GAG of U6 function in binding the 3' YAG/ during the second catalytic step.
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Affiliation(s)
- C A Collins
- Department of Biochemistry and Biophysics, University of California, San Francisco 94143, USA
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Krishnan L, Stanton AL, Collins CA, Liston VE, Jewell WR. Form or function? Part 2. Objective cosmetic and functional correlates of quality of life in women treated with breast-conserving surgical procedures and radiotherapy. Cancer 2001; 91:2282-7. [PMID: 11413516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
BACKGROUND Treatment-related factors that influence quality of life (QOL) for women who are diagnosed with breast carcinoma require study. This study was designed to examine the convergent validity of objective and subjective indices of cosmetic and functional status after patients undergo breast-conserving treatment (BCT) and to test the relations of the objective indicators with QOL. METHODS Women (n = 54 patients) who had received BCT and radiotherapy for Stage 0-II disease for whom the diagnosis duration ranged from 9 months to 18 years completed assessments of background information, perceived cosmetic and functional outcomes, and QOL. They also were administered a clinical breast examination, including objective ratings of arm edema and breast cosmesis. The patients were a subsample from the study reported by the authors in an accompanying article that is presented in this issue. RESULTS The findings revealed positive cosmetic and functional treatment outcomes, such that 82% of patients had no or minimal arm edema, and 70% of patients evidenced good or excellent cosmetic results. Convergent validity was demonstrated for the objective and subjective assessments of cosmetic and functional treatment outcomes. In addition, women who had more arm edema reported poorer QOL with regard to depressive symptoms (P < 0.05) and fear of disease recurrence (P < 0.05). CONCLUSIONS The findings from this study and those reported in the accompanying article reveal that functional treatment outcomes, such as arm edema and breast specific pain, are important correlates of QOL even many years after patients undergo BCT and radiotherapy. Both subjective and objective indicators of treatment outcomes are useful predictors of QOL.
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Affiliation(s)
- L Krishnan
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas 66160-7321, USA.
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Stanton AL, Krishnan L, Collins CA. Form or function? Part 1. Subjective cosmetic and functional correlates of quality of life in women treated with breast-conserving surgical procedures and radiotherapy. Cancer 2001; 91:2273-81. [PMID: 11413515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
BACKGROUND Quality of life (QOL) after a diagnosis of cancer varies considerably across individuals. Treatment-related factors that predict QOL for women who are diagnosed with breast carcinoma require further specification. This study was designed to develop a measure of perceived aesthetic (e.g., breast shape) and functional status (e.g., pain, mobility) after breast-conserving surgical treatment (BCT) and radiotherapy, to examine the relations of these indicators with patient QOL, and to determine whether these relations varied as a function of diagnosis duration. METHODS Women (n = 185 patients) who underwent BCT and radiotherapy for Stage 0-II disease for whom the diagnosis duration ranged from 3 months to 18 years completed assessments of background information, perceived cosmetic and functional treatment outcomes, and QOL. Medical data also were obtained from medical charts. RESULTS The Breast Cancer Treatment Outcome Scale (BCTOS) produced a coherent factor structure and three internally consistent subscales (i.e., cosmetic status, functional status, and breast specific pain) that demonstrated predictive validity. With patient age, diagnosis duration, and other BCTOS subscales controlled, greater breast specific pain predicted greater depressive symptoms (P < 0.01) and lower QOL related to mental health (P < 0.05) and physical health (P < 0.05). Cosmetic status predicted QOL related to physical health (P < 0.05). The relations of breast specific pain with QOL indicators varied somewhat as a function of diagnosis duration. CONCLUSIONS Although considerable research on treatment-relevant outcomes has addressed appearance-related concerns, functional parameters have not been explored fully. Findings suggest that functional consequences of treatment, and particularly breast specific pain, also are significant influences on patient QOL.
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Affiliation(s)
- A L Stanton
- Department of Psychology, University of Kansas, Lawrence, Kansas 66045-2160, USA.
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Collins CA. Ascites. Clin J Oncol Nurs 2001; 5:43-4. [PMID: 11899405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Affiliation(s)
- C A Collins
- School of Nursing, Texas Tech University Health Sciences Center, Lubbock, USA
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Abstract
The microtubule-based motor molecule cytoplasmic dynein has been proposed to be regulated by a variety of mechanisms, including phosphorylation and specific interaction with the organelle-associated complex, dynactin. In this study, we examined whether the intermediate chain subunits of cytoplasmic dynein are involved in modulation of ATP hydrolysis, and thereby affect motility. Treatment of testis cytoplasmic dynein under hypertonic salt conditions resulted in separation of the intermediate chains from the remainder of the dynein molecule, and led to a 4-fold enhancement of ATP hydrolysis. This result suggests that the accessory subunits act as negative regulators of dynein heavy chain activity. Comparison of ATPase activities of dyneins with differing intermediate chain isoforms showed significant differences in basal ATP hydrolysis rates, with testis dynein 7-fold more active than dynein from brain. Removal of the intermediate chain subunits led to an equalization of ATPase activity between brain and testis dyneins, suggesting that the accessory subunits are responsible for the observed differences in tissue activity. Finally, our preparative procedures have allowed for the identification and purification of a 1:1 complex of dynein with dynactin. As this interaction is presumed to be mediated by the dynein intermediate chain subunits, we now have defined experimental conditions for further exploration of dynein enzymatic and motility regulation.
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Affiliation(s)
- A R Kini
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois, USA
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40
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Stanton AL, Danoff-Burg S, Cameron CL, Bishop M, Collins CA, Kirk SB, Sworowski LA, Twillman R. Emotionally expressive coping predicts psychological and physical adjustment to breast cancer. J Consult Clin Psychol 2000; 68:875-82. [PMID: 11068973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
This study tested the hypothesis that coping through emotional approach, which involves actively processing and expressing emotions, enhances adjustment and health status for breast cancer patients. Patients (n = 92) completed measures within 20 weeks following medical treatment and 3 months later. Women who, at study entry, coped through expressing emotions surrounding cancer had fewer medical appointments for cancer-related morbidities, enhanced physical health and vigor, and decreased distress during the next 3 months compared with those low in emotional expression, with age, other coping strategy scores, and initial levels on dependent variables (except medical visits) controlled statistically. Expressive coping also was related to improved quality of life for those who perceived their social contexts as highly receptive. Coping through emotional processing was related to one index of greater distress over time. Analyses including dispositional hope suggested that expressive coping may serve as a successful vehicle for goal pursuit.
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Affiliation(s)
- A L Stanton
- Department of Psychology, University of Kansas, Lawrence 66045-2160, USA.
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41
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Abstract
The two phosphoryl transfer steps of pre-mRNA splicing are catalyzed within the large ribonuclear protein machine called the spliceosome. The highly dynamic nature of the spliceosome has presented many challenges to a structural and mechanistic understanding of its catalytic core. While much evidence supports the popular hypothesis that the catalytic steps of pre-mRNA splicing are mediated by spliceosomal RNA, a role for protein in catalysis cannot yet be ruled out. A highly conserved protein, Prp8, is a component of the catalytic core. We review data consistent with the hypothesis that Prp8 functions as a cofactor to an RNA enzyme.
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Affiliation(s)
- C A Collins
- Graduate Group in Biophysics, University of California, San Francisco, San Francisco, California 94143-0448, USA
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42
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Burke DJ, Collins CA, Mann RG. Cluster Selection and the Evolution of Brightest Cluster Galaxies. Astrophys J 2000; 532:L105-L108. [PMID: 10715235 DOI: 10.1086/312579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The K-band Hubble diagram of brightest cluster galaxies (BCGs) is presented for a large, X-ray-selected cluster sample extending out to z=0.8. The controversy over the degree of BCG evolution is shown to be due to sample selection since the BCG luminosity depends on the cluster environment. Selecting only the most X-ray luminous clusters produces a BCG sample that shows, under the assumption of an Einstein-de Sitter cosmology, significantly less mass growth than that predicted by current semianalytic galaxy formation models, and significant evidence of any growth only if the dominant stellar population of the BCGs formed relatively recently (z</=2.6).
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43
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Affiliation(s)
- C A Collins
- School of Public Health, University of California at Berkeley 94720-7360, USA.
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44
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Collins CA, Guthrie C. Allele-specific genetic interactions between Prp8 and RNA active site residues suggest a function for Prp8 at the catalytic core of the spliceosome. Genes Dev 1999; 13:1970-82. [PMID: 10444595 PMCID: PMC316919 DOI: 10.1101/gad.13.15.1970] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [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: 11/25/2022]
Abstract
The highly conserved spliceosomal protein Prp8 is known to cross-link the critical sequences at both the 5' (GU) and 3' (YAG) ends of the intron. We have identified prp8 mutants with the remarkable property of suppressing exon ligation defects due to mutations in position 2 of the 5' GU, and all positions of the 3' YAG. The prp8 mutants also suppress mutations in position A51 of the critical ACAGAG motif in U6 snRNA, which has been observed previously to cross-link position 2 of the 5' GU. Other mutations in the 5' splice site, branchpoint, and neighboring residues of the U6 ACAGAG motif are not suppressed. Notably, the suppressed residues are specifically conserved from yeast to man, and from U2- to U12-dependent spliceosomes. We propose that Prp8 participates in a previously unrecognized tertiary interaction between U6 snRNA and both the 5' and 3' ends of the intron. This model suggests a mechanism for positioning the 3' splice site for catalysis, and assigns a fundamental role for Prp8 in pre-mRNA splicing.
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MESH Headings
- Alleles
- Base Sequence
- Binding Sites
- Catalytic Domain
- Conserved Sequence/genetics
- Exons/genetics
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Genes, Suppressor/genetics
- Introns/genetics
- Models, Genetic
- Mutation/genetics
- Phenotype
- RNA Splicing/genetics
- RNA, Fungal/genetics
- RNA, Small Nuclear/genetics
- Regulatory Sequences, Nucleic Acid/genetics
- Ribonucleoprotein, U4-U6 Small Nuclear
- Ribonucleoprotein, U5 Small Nuclear
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae Proteins
- Spliceosomes/genetics
- Spliceosomes/metabolism
- Suppression, Genetic
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Affiliation(s)
- C A Collins
- Graduate Group in Biophysics, University of California San Francisco (UCSF), San Francisco, California 94143-0448, USA
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45
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Lu C, Stomper PC, Drislane FW, Wen PY, Block CC, Humphrey CC, Collins CA, Jolesz F, Talcott JA. Suspected spinal cord compression in breast cancer patients: a multidisciplinary risk assessment. Breast Cancer Res Treat 1998; 51:121-31. [PMID: 9879774 DOI: 10.1023/a:1006002823626] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [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: 11/12/2022]
Abstract
Breast cancer is the most common cause of metastatic epidural spinal cord compression (SCC) in women, and this condition results in significant neurologic dysfunction and morbidity. Prior studies of patients with suspected SCC did not employ multivariate analysis techniques, often included persons with a wide variety of malignancies, and generally focused on identifying associated neurologic and radiologic features. We therefore conducted a study examining a more comprehensive set of potential clinical risk factors in breast cancer patients with suspected SCC. We retrospectively analysed 123 episodes of suspected SCC among 93 breast cancer patients evaluated by spine computed tomography (CT) scanning. Multiple logistic regression analysis was employed to identify independent predictors of SCC. Clinically significant metastatic epidural cancer was defined as thecal sac compression (TSC), which occurred in 33 episodes (27%). Four independent predictors of TSC were identified and included oncologic features (known bone metastases > or = 2 years, metastatic disease at initial diagnosis) in addition to neurologic and radiologic features (objective weakness, vertebral compression fracture on spine radiograph). These four predictors stratified episodes into subgroups with widely varying risks of TSC, ranging from 12% (0 risk factors) to 85% (> or = 3 risk factors). These results suggest that the evaluation of breast cancer patients with suspected SCC should include clinical information about their disease course in addition to neurologic examination and prior imaging studies. If confirmed, these predictors may help clinicians assess risk in this patient population.
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Affiliation(s)
- C Lu
- Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
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Lin SX, Pfister KK, Collins CA. Comparison of the intracellular distribution of cytoplasmic dynein and kinesin in cultured cells: motor protein location does not reliably predict function. Cell Motil Cytoskeleton 1996; 34:299-312. [PMID: 8871817 DOI: 10.1002/(sici)1097-0169(1996)34:4<299::aid-cm5>3.0.co;2-3] [Citation(s) in RCA: 16] [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] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
While immunolocalization methods have been used as a reasonable means to judge where a given molecule may be active in the cellular milieu, the correlation between distribution and function for proteins involved in intracellular transport may not be clear cut. To address the question of specificity and reproducibility of immunolocalization of microtubule-based motor proteins, we have co-localized cytoplasmic dynein and kinesin by immunofluorescence microscopy using two specific antibodies for each motor molecule. The results indicate that cytoplasmic dynein and kinesin appear to co-localize on a small subset of vesicles, but largely reside or accumulate on morphologically distinct organelles. In addition, anti-kinesin antibodies differing in their epitope specificity label different cellular compartments. To address the question of whether the distribution of motor molecules is representative of organelles that are undergoing active transport, we have altered the activity of vesicle trafficking pathways in fibroblasts using several different methods, including cytoplasmic acidification and disruption of cellular compartments with brefeldin A, nocodazole and okadaic acid. Analysis of the distribution of cytoplasmic dynein and kinesin under these conditions indicates that immunolocalization data alone are not reliable indicators of sites of likely function for these microtubule-based motors.
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Affiliation(s)
- S X Lin
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA
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47
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Tuma PL, Collins CA. Dynamin forms polymeric complexes in the presence of lipid vesicles. Characterization of chemically cross-linked dynamin molecules. J Biol Chem 1995; 270:26707-14. [PMID: 7592898 DOI: 10.1074/jbc.270.44.26707] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Dynamin is a GTP-binding protein that is involved in the release of coated endocytic vesicles from the plasma membrane. We have been characterizing the enzymatic properties of purified rat brain dynamin to better understand how GTP binding and hydrolysis relate to its proposed function. Previously, we have demonstrated that activation of dynamin GTPase results from positive cooperative associations between dynamin molecules as they are bound to a polymeric surface. Our present report has extended these studies and has examined the structural features of dynamin self-association. After treatment with the zero-length protein cross-linking reagent, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide, dynamin in solution was found cross-linked into dimers. This homodimer likely reflects the native soluble state of the molecule. After binding to brain vesicles, dynamin was cross-linked into higher order oligomers of greater than 800 kDa. Dynamin, copurified on brain membranous organelles, also formed multimeric complexes when cross-linked suggesting dynamin exists in polymeric form in vivo. No cross-linked species other than homo-oligomers were observed, providing no evidence for close interactions between dynamin and membrane proteins. From experiments examining the effects of GTP, GDP, guanosine 5'-3-O-(thio)triphosphate, and 5'-guanylyl-beta,gamma-imidodiphosphate on cross-linking, we have determined that both dynamin membrane binding and self-association occur independently from the nucleotide-bound state of the enzyme. An 80-kDa dynamin fragment that is lacking its carboxyl-terminal domain is not cross-linked into higher order oligomers, suggesting that this domain is required for binding of dynamin to membranes and the subsequent enhancement of oligomerization. However, the dynamin fragment was found to form dimers indicating that this domain is not required for dynamin dimerization. Cross-linked dynamin was able to cooperatively bind microtubules, but did not exhibit GTPase activation. We propose that intramolecular cross-links in the dynamin monomer impart structural constraints that prevent the enhancement of GTP hydrolysis. We describe a model of the dynamin activation process to be considered in further investigations of the role for dynamin in endocytic vesicle formation.
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Affiliation(s)
- P L Tuma
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA
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48
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Abstract
In this study we report that phospholipid vesicles activate ATP hydrolysis by cytoplasmic dynein but not kinesin, consistent with reported differences in the organelle/vesicle binding of these motor proteins. Dynein activation by phospholipids was comparable with that seen in the presence of microtubules but was not sensitive to moderate salt concentrations and was independent of the net charge of the phospholipid, suggesting that the means of interaction between dynein and the lipid vesicle was not strictly ionic in nature. Based on this result, previous data that show that the interaction between dynein and vesicles is not ATP sensitive, and the concentration dependence observed for lipid activation of cytoplasmic dynein, it is likely that the binding interaction between dynein and liposomes is a stable one. In contrast to a previous report, microtubules increased the hydrolysis rate of all naturally occurring nucleotides tested, whereas only ATPase activity was stimulated by phospholipids. As ATP is the physiologically relevant substrate and is the only nucleotide to promote motility, the activation of only the ATPase by phospholipids may represent a means of discriminating between coupled and uncoupled nucleotide hydrolysis in vitro.
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Affiliation(s)
- K L Ferro
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008
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Tuma PL, Collins CA. Activation of dynamin GTPase is a result of positive cooperativity. J Biol Chem 1994; 269:30842-7. [PMID: 7983015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Dynamin is a GTP-binding protein thought to be involved in the early stages of endocytosis. Presently, it is not known how dynamin GTP binding and hydrolysis are related to its role in this process. We previously characterized the ability of acidic phospholipid vesicles and microtubules to strongly stimulate the GTPase activity of purified brain dynamin. In a further analysis of dynamin enzymatic properties, we have found that the increase of dynamin GTP hydrolysis in the presence of activating agent depends on enzyme concentration. At low enzyme concentration, little or no activation is observed. Plots of dynamin GTPase activity with increasing enzyme concentration in the presence of either activating agent are strongly sigmoidal, indicating that positive cooperativity is responsible for the increased activity observed. A Hill coefficient of 2.3 was determined, implying that at least two dynamin molecules associate for maximal GTPase activity. No cooperative effects in GTP binding were observed. Linear transformation of reaction velocity versus enzyme concentration data indicate an apparent Km for dynamin-dynamin interactions of 37 nM, which is significantly lower than the physiological concentration of dynamin in brain. These results suggest that cooperative interactions between dynamin molecules are responsible for the apparent activation of GTPase observed and are likely involved in dynamin function in vivo.
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Affiliation(s)
- P L Tuma
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611-3008
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50
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