1
|
Burk K. The endocytosis, trafficking, sorting and signaling of neurotrophic receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 196:141-165. [PMID: 36813356 DOI: 10.1016/bs.pmbts.2022.06.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Neurotrophins are soluble factors secreted by neurons themselves as well as by post-synaptic target tissues. Neurotrophic signaling regulates several processes such as neurite growth, neuronal survival and synaptogenesis. In order to signal, neurotrophins bind to their receptors, the tropomyosin receptor tyrosine kinase (Trk), which causes internalization of the ligand-receptor complex. Subsequently, this complex is routed into the endosomal system from where Trks can start their downstream signaling. Depending on their endosomal localization, co-receptors involved, but also due to the expression patterns of adaptor proteins, Trks regulate a variety of mechanisms. In this chapter, I provide an overview of the endocytosis, trafficking, sorting and signaling of neurotrophic receptors.
Collapse
Affiliation(s)
- Katja Burk
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany.
| |
Collapse
|
2
|
Markworth R, Dambeck V, Steinbeck LM, Koufali A, Bues B, Dankovich TM, Wichmann C, Burk K. Tubular microdomains of Rab7-positive endosomes retrieve TrkA, a mechanism disrupted in Charcot-Marie-Tooth disease 2B. J Cell Sci 2021; 134:272650. [PMID: 34486665 DOI: 10.1242/jcs.258559] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 08/23/2021] [Indexed: 01/04/2023] Open
Abstract
Axonal survival and growth requires signalling from tropomyosin receptor kinases (Trks). To transmit their signals, receptor-ligand complexes are endocytosed and undergo retrograde trafficking to the soma, where downstream signalling occurs. Vesicles transporting neurotrophic receptors to the soma are reported to be Rab7-positive late endosomes and/or multivesicular bodies (MVBs), where receptors localize within so-called intraluminal vesicles (herein Rab7 corresponds to Rab7A unless specified otherwise). Therefore, one challenging question is how downstream signalling is possible given the insulating properties of intraluminal vesicles. In this study, we report that Rab7-positive endosomes and MVBs retrieve TrkA (also known as NTRK1) through tubular microdomains. Interestingly, this phenotype is absent for the EGF receptor. Furthermore, we found that endophilinA1, endophilinA2 and endophilinA3, together with WASH1 (also known as WASHC1), are involved in the tubulation process. In Charcot-Marie-Tooth disease 2B (CMT2B), a neuropathy of the peripheral nervous system, this tubulating mechanism is disrupted. In addition, the ability to tubulate correlates with the phosphorylation levels of TrkA as well as with neurite length in neuronal cultures from dorsal root ganglia. In all, we report a new retrieval mechanism of late Rab7-positive endosomes, which enables TrkA signalling and sheds new light onto how neurotrophic signalling is disrupted in CMT2B. This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Ronja Markworth
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,European Neuroscience Institute, Grisebachstraße 5, 37077 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Vivian Dambeck
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Lars Malte Steinbeck
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Angeliki Koufali
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Bastian Bues
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| | - Tal M Dankovich
- Institute for Neuro- and Sensory Physiology, Humboldtallee 23, 37073 Göttingen, Germany
| | - Carolin Wichmann
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany.,Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Centers 889 'Cellular Mechanisms of Sensory Processing' and 1286 'Quantitative Synaptology', 37099 Göttingen, Germany
| | - Katja Burk
- Department of Neurology, University Medical Center Göttingen, Robert Koch Straße 40, 37075 Göttingen, Germany.,European Neuroscience Institute, Grisebachstraße 5, 37077 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold Straße 3A, 37075 Göttingen, Germany
| |
Collapse
|
3
|
Villarroel-Campos D, Schiavo G, Lazo OM. The many disguises of the signalling endosome. FEBS Lett 2018; 592:3615-3632. [PMID: 30176054 PMCID: PMC6282995 DOI: 10.1002/1873-3468.13235] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 08/29/2018] [Indexed: 01/09/2023]
Abstract
Neurons are highly complex and polarised cells that must overcome a series of logistic challenges to maintain homeostasis across their morphological domains. A very clear example is the propagation of neurotrophic signalling from distal axons, where target-released neurotrophins bind to their receptors and initiate signalling, towards the cell body, where nuclear and cytosolic responses are integrated. The mechanisms of propagation of neurotrophic signalling have been extensively studied and, eventually, the model of a 'signalling endosome', transporting activated receptors and associated complexes, has emerged. Nevertheless, the exact nature of this organelle remains elusive. In this Review, we examine the evidence for the retrograde transport of neurotrophins and their receptors in endosomes, outline some of their diverse physiological and pathological roles, and discuss the main interactors, morphological features and trafficking destinations of a highly flexible endosomal signalling organelle with multiple molecular signatures.
Collapse
Affiliation(s)
- David Villarroel-Campos
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, UK.,UK Dementia Research Institute at UCL, London, UK.,Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, UK
| | - Oscar Marcelo Lazo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, UK
| |
Collapse
|
4
|
Scott-Solomon E, Kuruvilla R. Mechanisms of neurotrophin trafficking via Trk receptors. Mol Cell Neurosci 2018; 91:25-33. [PMID: 29596897 DOI: 10.1016/j.mcn.2018.03.013] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/19/2018] [Accepted: 03/26/2018] [Indexed: 12/31/2022] Open
Abstract
In neurons, long-distance communication between axon terminals and cell bodies is a critical determinant in establishing and maintaining neural circuits. Neurotrophins are soluble factors secreted by post-synaptic target tissues that retrogradely control axon and dendrite growth, survival, and synaptogenesis of innervating neurons. Neurotrophins bind Trk receptor tyrosine kinases in axon terminals to promote endocytosis of ligand-bound phosphorylated receptors into signaling endosomes. Trk-harboring endosomes function locally in axons to acutely promote growth events, and can also be retrogradely transported long-distances to remote cell bodies and dendrites to stimulate cytoplasmic and transcriptional signaling necessary for neuron survival, morphogenesis, and maturation. Neuronal responsiveness to target-derived neurotrophins also requires the precise axonal targeting of newly synthesized Trk receptors. Recent studies suggest that anterograde delivery of Trk receptors is regulated by retrograde neurotrophin signaling. In this review, we summarize current knowledge on the functions and mechanisms of retrograde trafficking of Trk signaling endosomes, and highlight recent discoveries on the forward trafficking of nascent receptors.
Collapse
Affiliation(s)
- Emily Scott-Solomon
- Department of Biology, Johns Hopkins University, 3400 N. Charles St, 227 Mudd Hall, Baltimore, MD 21218, USA
| | - Rejji Kuruvilla
- Department of Biology, Johns Hopkins University, 3400 N. Charles St, 227 Mudd Hall, Baltimore, MD 21218, USA.
| |
Collapse
|
5
|
Matusica D, Coulson EJ. Local versus long-range neurotrophin receptor signalling: endosomes are not just carriers for axonal transport. Semin Cell Dev Biol 2014; 31:57-63. [PMID: 24709025 DOI: 10.1016/j.semcdb.2014.03.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 01/25/2023]
Abstract
Neurotrophins play a critical role in neuronal development and survival, as well as maintenance of the adult nervous system. Neurotrophins can mediate their effects by signalling locally at the nerve terminal, or signalling retrogradely from the axonal terminal to the cell soma to regulate gene expression. Given that the axon terminals of many nerve cells can be up to a metre away from their soma, neurons have evolved specialized long-range signalling platforms that depend on a highly regulated network of intracellular membrane compartments termed "signalling endosomes". Endosomal trafficking of activated receptors controls not only the axonal retrograde signals but also local receptor recycling and degradation. Endosomal trafficking involving the sorting and compartmentalizing of different signals, which are subsequently distributed to the appropriate cellular destination, can at least partially explain how neurotrophins generate a diverse array of signalling outcomes. Although signalling endosomes provide a useful model for understanding how different cell surface receptor-mediated signals are generated and transported, the precise role, identity and functional definition of a signalling endosome remains unclear. In this review we will discuss the regulation of local versus long-range neurotrophin signalling, with a specific focus on recent developments in the role of endosomes in regulating the fate of Trk receptors.
Collapse
Affiliation(s)
- Dusan Matusica
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane 4072 Qld, Australia
| | - Elizabeth J Coulson
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane 4072 Qld, Australia.
| |
Collapse
|
6
|
Schmieg N, Menendez G, Schiavo G, Terenzio M. Signalling endosomes in axonal transport: Travel updates on the molecular highway. Semin Cell Dev Biol 2014; 27:32-43. [DOI: 10.1016/j.semcdb.2013.10.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Revised: 10/17/2013] [Accepted: 10/19/2013] [Indexed: 01/11/2023]
|
7
|
Drain of the brain: low-affinity p75 neurotrophin receptor affords a molecular sink for clearance of cortical amyloid β by the cholinergic modulator system. Neurobiol Aging 2013; 34:2517-24. [DOI: 10.1016/j.neurobiolaging.2013.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 03/09/2013] [Accepted: 05/04/2013] [Indexed: 12/13/2022]
|
8
|
Xie W, Zhang K, Cui B. Functional characterization and axonal transport of quantum dot labeled BDNF. Integr Biol (Camb) 2012; 4:953-60. [PMID: 22772872 PMCID: PMC3462492 DOI: 10.1039/c2ib20062g] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Brain derived neurotrophic factor (BDNF) plays a key role in the growth, development and maintenance of the central and peripheral nervous systems. Exogenous BDNF activates its membrane receptors at the axon terminal, and subsequently sends regulation signals to the cell body. To understand how a BDNF signal propagates in neurons, it is important to follow the trafficking of BDNF after it is internalized at the axon terminal. Here we labeled BDNF with bright, photostable quantum dots (QD-BDNF) and followed the axonal transport of QD-BDNF in real time in hippocampal neurons. We showed that QD-BDNF was able to bind BDNF receptors and activate downstream signaling pathways. When QD-BDNF was applied to the distal axons of hippocampal neurons, it was observed to be actively transported toward the cell body at an average speed of 1.11 ± 0.05 μm s(-1). A closer examination revealed that QD-BDNF was transported by both discrete endosomes and multivesicular body-like structures. Our results showed that QD-BDNF could be used to track the movement of exogenous BDNF in neurons over long distances and to study the signaling organelles that contain BDNF.
Collapse
Affiliation(s)
- Wenjun Xie
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Kai Zhang
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Bianxiao Cui
- Department of Chemistry, Stanford University, Stanford, CA, USA
| |
Collapse
|
9
|
Abstract
Neurotrophins are a family of target-derived growth factors that support survival, development, and maintenance of innervating neurons. Owing to the unique architecture of neurons, neurotrophins that act locally on the axonal terminals must convey their signals across the entire axon for subsequent regulation of gene transcription in the cell nucleus. This long-distance retrograde signaling, a motor-driven process that can take hours or days, has been a subject of intense interest. In the last decade, live-cell imaging with high sensitivity has significantly increased our capability to track the transport of neurotrophins, their receptors, and subsequent signals in real time. This review summarizes recent research progress in understanding neurotrophin-receptor interactions at the axonal terminal and their transport dynamics along the axon. We emphasize high-resolution studies at the single-molecule level and also discuss recent technical advances in the field.
Collapse
|
10
|
Tuck E, Cavalli V. Roles of membrane trafficking in nerve repair and regeneration. Commun Integr Biol 2011; 3:209-14. [PMID: 20714395 DOI: 10.4161/cib.3.3.11555] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2010] [Accepted: 02/14/2010] [Indexed: 02/06/2023] Open
Abstract
Successful axonal repair following injury is critical for nerve regeneration and functional recovery. Nerve repair relies on three functionally distinct events involving membrane trafficking. First, axonally transported vesicles accumulate, while others are generated at the cut end to restore a selective barrier to the severed axon. Then, retrograde transport of vesicles along microtubules informs the cell body that damage has occurred in the distal axon. Finally, membrane addition to a newly formed growth cone, or to the axonal membrane is required to promote axonal re-growth and elongation. Yet, how these membrane trafficking events are regulated and what are the identities of the molecules and organelles involved remains largely unknown. Several potential factors have been recently identified. Members of the SNARE machinery appear to regulate fusion of vesicles in a calcium-dependent manner to promote axolemmal resealing. Retrograde transport of endosomes powered by the dynein-dynactin molecular motor complex represents a potential injury-signaling platform. Several classes of secretory and endocytic vesicles may coordinate axonal membrane extension and re-growth. Here we discuss recent advances in understanding the mechanisms of the membrane trafficking involved in nerve repair.
Collapse
Affiliation(s)
- Elizabeth Tuck
- Department of Anatomy and Neurobiology; Washington University in St. Louis; St. Louis, MO USA
| | | |
Collapse
|
11
|
Mohamed A, Posse de Chaves E. Aβ internalization by neurons and glia. Int J Alzheimers Dis 2011; 2011:127984. [PMID: 21350608 PMCID: PMC3042623 DOI: 10.4061/2011/127984] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Accepted: 12/23/2010] [Indexed: 11/20/2022] Open
Abstract
In the brain, the amyloid β peptide (Aβ) exists extracellularly and inside neurons. The intracellular accumulation of Aβ in Alzheimer's disease brain has been questioned for a long time. However, there is now sufficient strong evidence indicating that accumulation of Aβ inside neurons plays an important role in the pathogenesis of Alzheimer's disease. Intraneuronal Aβ originates from intracellular cleavage of APP and from Aβ internalization from the extracellular milieu. We discuss here the different molecular mechanisms that are responsible for Aβ internalization in neurons and the links between Aβ internalization and neuronal dysfunction and death. A brief description of Aβ uptake by glia is also presented.
Collapse
Affiliation(s)
- Amany Mohamed
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | | |
Collapse
|
12
|
Liu Z, Huang Y, Zhang Y, Chen D, Zhang YQ. Drosophila Acyl-CoA synthetase long-chain family member 4 regulates axonal transport of synaptic vesicles and is required for synaptic development and transmission. J Neurosci 2011; 31:2052-63. [PMID: 21307243 PMCID: PMC6633061 DOI: 10.1523/jneurosci.3278-10.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 11/22/2010] [Accepted: 12/02/2010] [Indexed: 11/21/2022] Open
Abstract
Acyl-CoA synthetase long-chain family member 4 (ACSL4) converts long-chain fatty acids to acyl-CoAs that are indispensable for lipid metabolism and cell signaling. Mutations in ACSL4 cause nonsyndromic X-linked mental retardation. We previously demonstrated that Drosophila dAcsl is functionally homologous to human ACSL4, and is required for axonal targeting in the brain. Here, we report that Drosophila dAcsl mutants exhibited distally biased axonal aggregates that were immunopositive for the synaptic-vesicle proteins synaptotagmin (Syt) and cysteine-string protein, the late endosome/lysosome marker lysosome-associated membrane protein 1, the autophagosomal marker Atg8, and the multivesicular body marker Hrs (hepatocyte growth factor-regulated tyrosine kinase substrate). In contrast, the axonal distribution of mitochondria and the cell adhesion molecule Fas II (fasciclin II) was normal. Electron microscopy revealed accumulation of prelysomes and multivesicle bodies. These aggregates appear as retrograde instead of anterograde cargos. Live imaging analysis revealed that dAcsl mutations increased the velocity of anterograde transport but reduced the flux, velocity, and processivity of retrograde transport of Syt-enhanced green fluorescent protein-labeled vesicles. Immunohistochemical and electrophysiological analyses showed significantly reduced growth and stability of neuromuscular synapses, and impaired glutamatergic neurotransmission in dAcsl mutants. The axonal aggregates and synaptic defects in dAcsl mutants were fully rescued by neuronal expression of human ACSL4, supporting a functional conservation of ACSL4 across species in the nervous system. Together, our findings demonstrate that dAcsl regulates axonal transport of synaptic vesicles and is required for synaptic development and function. Defects in axonal transport and synaptic function may account, at least in part, for the pathogenesis of ACSL4-related mental retardation.
Collapse
Affiliation(s)
- Zhihua Liu
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Huang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yi Zhang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Di Chen
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yong Q. Zhang
- Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| |
Collapse
|
13
|
Von Bartheld CS, Altick AL. Multivesicular bodies in neurons: distribution, protein content, and trafficking functions. Prog Neurobiol 2011; 93:313-40. [PMID: 21216273 DOI: 10.1016/j.pneurobio.2011.01.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 12/22/2010] [Accepted: 01/03/2011] [Indexed: 11/27/2022]
Abstract
Multivesicular bodies (MVBs) are intracellular endosomal organelles characterized by multiple internal vesicles that are enclosed within a single outer membrane. MVBs were initially regarded as purely prelysosomal structures along the degradative endosomal pathway of internalized proteins. MVBs are now known to be involved in numerous endocytic and trafficking functions, including protein sorting, recycling, transport, storage, and release. This review of neuronal MVBs summarizes their research history, morphology, distribution, accumulation of cargo and constitutive proteins, transport, and theories of functions of MVBs in neurons and glia. Due to their complex morphologies, neurons have expanded trafficking and signaling needs, beyond those of "geometrically simpler" cells, but it is not known whether neuronal MVBs perform additional transport and signaling functions. This review examines the concept of compartment-specific MVB functions in endosomal protein trafficking and signaling within synapses, axons, dendrites and cell bodies. We critically evaluate reports of the accumulation of neuronal MVBs based on evidence of stress-induced MVB formation. Furthermore, we discuss potential functions of neuronal and glial MVBs in development, in dystrophic neuritic syndromes, injury, disease, and aging. MVBs may play a role in Alzheimer's, Huntington's, and Niemann-Pick diseases, some types of frontotemporal dementia, prion and virus trafficking, as well as in adaptive responses of neurons to trauma and toxin or drug exposure. Functions of MVBs in neurons have been much neglected, and major gaps in knowledge currently exist. Developing truly MVB-specific markers would help to elucidate the roles of neuronal MVBs in intra- and intercellular signaling of normal and diseased neurons.
Collapse
Affiliation(s)
- Christopher S Von Bartheld
- Department of Physiology and Cell Biology, Mailstop 352, University of Nevada School of Medicine, Reno, NV 89557, USA.
| | | |
Collapse
|
14
|
A perspective on neuronal cell death signaling and neurodegeneration. Mol Neurobiol 2010; 42:25-31. [PMID: 20480262 DOI: 10.1007/s12035-010-8128-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 04/05/2010] [Indexed: 12/12/2022]
Abstract
Although neuronal cell death through apoptotic pathways represents a common feature of dysferopathies, the canonical apoptotic changes familiar from nonneuronal cells are late events. Loss of neuronal function occurs at a much early time, when synaptic-based neuronal connectivity fails. In this context, apoptotic pathways may normally serve a cleanup role, rather than a pathogenic one. Reframing the consideration of cell death in the nervous system to include the early stages of axonal degeneration provides a better understanding of the roles played by various apoptotic signaling pathways in neurodegenerative diseases. Focusing on disease-specific mechanisms that initiate the sequence that eventually leads to neuronal loss should facilitate development of therapies that preserve neuronal function and neuronal numbers.
Collapse
|
15
|
Abe N, Almenar-Queralt A, Lillo C, Shen Z, Lozach J, Briggs SP, Williams DS, Goldstein LSB, Cavalli V. Sunday driver interacts with two distinct classes of axonal organelles. J Biol Chem 2009; 284:34628-39. [PMID: 19801628 PMCID: PMC2787325 DOI: 10.1074/jbc.m109.035022] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 09/25/2009] [Indexed: 11/06/2022] Open
Abstract
The extreme polarized morphology of neurons poses a challenging problem for intracellular trafficking pathways. The distant synaptic terminals must communicate via axonal transport with the cell soma for neuronal survival, function, and repair. Multiple classes of organelles transported along axons may establish and maintain the polarized morphology of neurons, as well as control signaling and neuronal responses to extracellular cues such as neurotrophic or stress factors. We reported previously that the motor-binding protein Sunday Driver (syd), also known as JIP3 or JSAP1, links vesicular axonal transport to injury signaling. To better understand syd function in axonal transport and in the response of neurons to injury, we developed a purification strategy based on anti-syd antibodies conjugated to magnetic beads to identify syd-associated axonal vesicles. Electron microscopy analyses revealed two classes of syd-associated vesicles of distinct morphology. To identify the molecular anatomy of syd vesicles, we determined their protein composition by mass spectrometry. Gene Ontology analyses of each vesicle protein content revealed their unique identity and indicated that one class of syd vesicles belongs to the endocytic pathway, whereas another may belong to an anterogradely transported vesicle pool. To validate these findings, we examined the transport and localization of components of syd vesicles within axons of mouse sciatic nerve. Together, our results lead us to propose that endocytic syd vesicles function in part to carry injury signals back to the cell body, whereas anterograde syd vesicles may play a role in axonal outgrowth and guidance.
Collapse
Affiliation(s)
- Namiko Abe
- From the Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, Missouri 63110
| | | | | | - Zhouxin Shen
- the Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, and
| | - Jean Lozach
- the Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute
| | - Steven P. Briggs
- the Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, and
| | - David S. Williams
- the Departments of Pharmacology and Neurosciences, and
- the Departments of Ophthalmology and Neurosciences, Jules Stein Eye Institute, UCLA, Los Angeles, California 90095
| | | | - Valeria Cavalli
- From the Department of Anatomy and Neurobiology, Washington University in St. Louis, St. Louis, Missouri 63110
| |
Collapse
|
16
|
Lively S, Brown IR. The extracellular matrix protein SC1/Hevin localizes to multivesicular bodies in Bergmann glial fibers in the adult rat cerebellum. Neurochem Res 2009; 35:315-22. [PMID: 19757034 DOI: 10.1007/s11064-009-0057-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 08/28/2009] [Indexed: 02/06/2023]
Abstract
SC1 is an extracellular matrix molecule prominent in the mammalian brain. In the cerebellum, SC1 localizes to Bergmann glial cells and perisynaptic glial processes that envelop synapses in the molecular layer. In the present study, confocal microscopy revealed a punctate distribution of SC1 along Bergmann glial fibers that colocalized with the intermediate filament GFAP when fibers were viewed in cross-section. Immunoelectron microscopy showed that the punctate SC1 pattern corresponded to the localization of SC1 in multivesicular bodies situated within Bergmann glial fibers. The pattern of SC1 localization was not disrupted following hyperthermia or pilocarpine-induced status epilepticus. The present study suggests that SC1 protein may reach its destination in perisynaptic glial processes and glial endfeet by transport along Bergmann glial fibers in multivesicular bodies and that this process is preserved following stress.
Collapse
Affiliation(s)
- Starlee Lively
- Center for the Neurobiology of Stress, University of Toronto at Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | | |
Collapse
|
17
|
Altick AL, Baryshnikova LM, Vu TQ, von Bartheld CS. Quantitative analysis of multivesicular bodies (MVBs) in the hypoglossal nerve: evidence that neurotrophic factors do not use MVBs for retrograde axonal transport. J Comp Neurol 2009; 514:641-57. [PMID: 19363811 DOI: 10.1002/cne.22047] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multivesicular bodies (MVBs) are defined by multiple internal vesicles enclosed within an outer, limiting membrane. MVBs have previously been quantified in neuronal cell bodies and in dendrites, but their frequencies and significance in axons are controversial. Despite lack of conclusive evidence, it is widely believed that MVBs are the primary organelle that carries neurotrophic factors in axons. Reliable information about axonal MVBs under physiological and pathological conditions is needed for a realistic assessment of their functional roles in neurons. We provide a quantitative ultrastructural analysis of MVBs in the normal postnatal rat hypoglossal nerve and under a variety of experimental conditions. MVBs were about 50 times less frequent in axons than in neuronal cell bodies or dendrites. Five distinct types of MVBs were distinguished in axons, based on MVB size, electron density, and size of internal vesicles. Although target manipulations did not significantly change MVBs in axons, dystrophic conditions such as delayed fixation substantially increased the number of axonal MVBs. Radiolabeled brain- and glial-cell derived neurotrophic factors (BDNF and GDNF) injected into the tongue did not accumulate during retrograde axonal transport in MVBs, as determined by quantitative ultrastructural autoradiography, and confirmed by analysis of quantum dot-labeled BDNF. We conclude that for axonal transport, neurotrophic factors utilize small vesicles or endosomes that can be inconspicuous at transmission electron microscopic resolution, rather than MVBs. Previous reports of axonal MVBs may be based, in part, on artificial generation of such organelles in axons due to dystrophic conditions.
Collapse
Affiliation(s)
- Amy L Altick
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
| | | | | | | |
Collapse
|
18
|
LeBlanc-Straceski JM, Sokac A, Bement W, Sobrado P, Lemoine L. Developmental expression of Xenopus myosin 1d and identification of a myo1d tail homology that overlaps TH1. Dev Growth Differ 2009; 51:443-51. [DOI: 10.1111/j.1440-169x.2009.01107.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
19
|
Cosker KE, Courchesne SL, Segal RA. Action in the axon: generation and transport of signaling endosomes. Curr Opin Neurobiol 2009; 18:270-5. [PMID: 18778772 DOI: 10.1016/j.conb.2008.08.005] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 08/11/2008] [Accepted: 08/12/2008] [Indexed: 11/26/2022]
Abstract
Neurons extend axonal processes over long distances, necessitating efficient transport mechanisms to convey target-derived neurotrophic survival signals from remote distal axons to cell bodies. Retrograde transport, powered by dynein motors, supplies cell bodies with survival signals in the form of 'signaling endosomes'. In this review, we will discuss new advances in our understanding of the motor proteins that bind to and move signaling components in a retrograde direction and discuss mechanisms that might specify distinct neuronal responses to spatially restricted neurotrophin signals. Disruption of retrograde transport leads to a variety of neurodegenerative diseases, highlighting the role of retrograde transport of signaling endosomes for axonal maintenance and the importance of efficient transport for neuronal survival and function.
Collapse
Affiliation(s)
- Katharina E Cosker
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
| | | | | |
Collapse
|
20
|
Abe N, Cavalli V. Nerve injury signaling. Curr Opin Neurobiol 2009; 18:276-83. [PMID: 18655834 DOI: 10.1016/j.conb.2008.06.005] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Accepted: 06/25/2008] [Indexed: 01/05/2023]
Abstract
Although neurons within the peripheral nervous system (PNS) have a remarkable ability to repair themselves after injury, neurons within the central nervous system (CNS) do not spontaneously regenerate. This problem has remained recalcitrant despite a century of research on the reaction of axons to injury. The balance between inhibitory cues present in the environment and the intrinsic growth capacity of the injured neuron determines the extent of axonal regeneration following injury. The cell body of an injured neuron must receive accurate and timely information about the site and extent of axonal damage in order to increase its intrinsic growth capacity and successfully regenerate. One of the mechanisms contributing to this process is retrograde transport of injury signals. For example, molecules activated at the injury site convey information to the cell body leading to the expression of regeneration-associated genes and increased growth capacity of the neuron. Here we discuss recent studies that have begun to dissect the injury-signaling pathways involved in stimulating the intrinsic growth capacity of injured neurons.
Collapse
Affiliation(s)
- Namiko Abe
- Department of Anatomy and Neurobiology, Washington University in St. Louis, 660 S Euclid Avenue, St. Louis, MO 63110-1093, USA
| | | |
Collapse
|
21
|
Herpes simplex virus utilizes the large secretory vesicle pathway for anterograde transport of tegument and envelope proteins and for viral exocytosis from growth cones of human fetal axons. J Virol 2009; 83:3187-99. [PMID: 19176621 DOI: 10.1128/jvi.01579-08] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Axonal transport of herpes simplex virus (HSV-1) is essential for viral infection and spread in the peripheral nervous system of the host. Therefore, the virus probably utilizes existing active transport and targeting mechanisms in neurons for virus assembly and spread from neurons to skin. In the present study, we used transmission immunoelectron microscopy to investigate the nature and origin of vesicles involved in the anterograde axonal transport of HSV-1 tegument and envelope proteins and of vesicles surrounding partially and fully enveloped capsids in growth cones. This study aimed to elucidate the mechanism of virus assembly and exit from axons of human fetal dorsal root ganglia neurons. We demonstrated that viral tegument and envelope proteins can travel in axons independently of viral capsids and were transported to the axon terminus in two types of transport vesicles, tubulovesicular membrane structures and large dense-cored vesicles. These vesicles and membrane carriers were derived from the trans-Golgi network (TGN) and contained key proteins, such as Rab3A, SNAP-25, GAP-43, and kinesin-1, involved in the secretory and exocytic pathways in axons. These proteins were also observed on fully and partially enveloped capsids in growth cones and on extracellular virions. Our findings provide further evidence to the subassembly model of separate transport in axons of unenveloped capsids from envelope and tegument proteins with final virus assembly occurring at the axon terminus. We postulate that HSV-1 capsids invaginate tegument- and envelope-bearing TGN-derived vesicles and utilize the large secretory vesicle pathway of exocytosis for exit from axons.
Collapse
|
22
|
Wu C, Cui B, He L, Chen L, Mobley WC. The coming of age of axonal neurotrophin signaling endosomes. J Proteomics 2008; 72:46-55. [PMID: 19028611 DOI: 10.1016/j.jprot.2008.10.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 10/21/2008] [Accepted: 10/23/2008] [Indexed: 01/30/2023]
Abstract
Neurons of both the central and the peripheral nervous system are critically dependent on neurotrophic signals for their survival and differentiation. The trophic signal is originated at the axonal terminals that innervate the target(s). It has been well established that the signal must be retrogradely transported back to the cell body to exert its trophic effect. Among the many forms of transmitted signals, the signaling endosome serves as a primary means to ensure that the retrograde signal is delivered to the cell body with sufficient fidelity and specificity. Recent evidence suggests that disruption of axonal transport of neurotrophin signals may contribute to neurodegenerative diseases such as Alzheimer's disease and Down syndrome. However, the identity of the endocytic vesicular carrier(s), and the mechanisms involved in retrogradely transporting the signaling complexes remain a matter of debate. In this review, we summarize current insights that are mainly based on classical hypothesis-driven research, and we emphasize the urgent needs to carry out proteomics to resolve the controversies in the field.
Collapse
Affiliation(s)
- Chengbiao Wu
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California 94305-5489, United States.
| | | | | | | | | |
Collapse
|
23
|
Kaasinen SK, Harvey L, Reynolds AJ, Hendry IA. Autophagy generates retrogradely transported organelles: a hypothesis. Int J Dev Neurosci 2008; 26:625-34. [PMID: 18499388 DOI: 10.1016/j.ijdevneu.2008.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 03/25/2008] [Accepted: 03/26/2008] [Indexed: 12/15/2022] Open
Abstract
Nerve cells require trophic signals transmitted from the nerve terminal via the axon in order to survive and develop normally. As the axon may be more than a meter long, specialised mechanisms are needed to transmit these signals. This involves the retrograde axonal transport of signalling endosomes containing nerve growth factor (NGF) and other synaptically derived molecules. These are large, double membrane multivesicular bodies containing a mixture of all vesicle types seen in the nerve terminal. How this signalling endosome is formed and targeted for retrograde axonal transport, however, remains an open question. Here we show that members of the Rab family of proteins that are retrogradely transported indicate that the signalling endosome contains both early and recycling endosomes. In addition, we show that retrogradely transported labelled antibody to dopamine beta-hydroxylase, a marker for synaptic vesicles, co-localizes within the same signalling endosome as NGF. We further show that LC3, a marker for autophagosomes, is retrogradely transported and associates with retrogradely transported NGF. We propose that neurons have exploited the mechanism of autophagy to engulf a sample of the cytoplasmic contents of the nerve terminal to transport back to the cell body. This sample of cytoplasmic contents relays a reliable snapshot of the totality of signalling events occurring in the nerve terminal at that instant in time.
Collapse
Affiliation(s)
- Selma K Kaasinen
- Developmental Neurobiology Group, John Curtin School of Medical Research, Australian National University, Box 334, Canberra ACT 2601, Australia.
| | | | | | | |
Collapse
|
24
|
Taylor AR, Robinson MB, Gifondorwa DJ, Tytell M, Milligan CE. Regulation of heat shock protein 70 release in astrocytes: role of signaling kinases. Dev Neurobiol 2007; 67:1815-29. [PMID: 17701989 DOI: 10.1002/dneu.20559] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ability to mount a successful stress response in the face of injury is critical to the long-term viability of individual cells and to the organism in general. The stress response, characterized in part by the upregulation of heat shock proteins, is compromised in several neurodegenerative disorders and in some neuronal populations, including motoneurons (MNs). Because astrocytes have a greater capacity than neurons to survive metabolic stress, and because they are intimately associated with the regulation of neuronal function, it is important to understand their stress response, so that we may to better appreciate the impact of stress on neuronal viability during injury or disease. We show that astrocytes subjected to hyperthermia upregulate Hsp/c70 in addition to intracellular signaling components including activated forms of extracellular-signal-regulated kinase (ERK1/2), Akt, and c-jun N-terminal kinase/stress activated protein kinase (JNK/SAPK). Furthermore, astrocytes release increasing amounts of Hsp/c70 into the extracellular environment following stress, an event that is abrogated when signaling through the ERK1/2 and phosphatidylinositol-3 kinase (PI3K) pathways is compromised and enhanced by inhibition of the JNK pathway. Last, we show that the Hsp/c70 is released from astrocytes in exosomes. Together, these data illustrate the diverse regulation of stress-induced Hsp/c70 release in exosomes, and the way in which the balance of activated signal transduction pathways affects this release. These data highlight how stressful insults can alter the microenvironment of an astrocyte, which may ultimately have implications for the survival of neighboring neurons.
Collapse
Affiliation(s)
- Anna R Taylor
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
| | | | | | | | | |
Collapse
|
25
|
Smalheiser NR. Exosomal transfer of proteins and RNAs at synapses in the nervous system. Biol Direct 2007; 2:35. [PMID: 18053135 PMCID: PMC2219957 DOI: 10.1186/1745-6150-2-35] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 11/30/2007] [Indexed: 11/10/2022] Open
Abstract
Background Many cell types have been reported to secrete small vesicles called exosomes, that are derived from multivesicular bodies and that can also form from endocytic-like lipid raft domains of the plasma membrane. Secretory exosomes contain a characteristic composition of proteins, and a recent report indicates that mast cell exosomes harbor a variety of mRNAs and microRNAs as well. Exosomes express cell recognition molecules on their surface that facilitate their selective targeting and uptake into recipient cells. Results In this review, I suggest that exosomal secretion of proteins and RNAs may be a fundamental mode of communication within the nervous system, supplementing the known mechanisms of anterograde and retrograde signaling across synapses. In one specific scenario, exosomes are proposed to bud from the lipid raft region of the postsynaptic membrane adjacent to the postsynaptic density, in a manner that is stimulated by stimuli that elicit long-term potentiation. The exosomes would then transfer newly synthesized synaptic proteins (such as CAM kinase II alpha) and synaptic RNAs to the presynaptic terminal, where they would contribute to synaptic plasticity. Conclusion The model is consistent with the known cellular and molecular features of synaptic neurobiology and makes a number of predictions that can be tested in vitro and in vivo. Open peer review Reviewed by Etienne Joly, Gaspar Jekely, Juergen Brosius and Eugene Koonin. For the full reviews, please go to the Reviewers' comments section.
Collapse
Affiliation(s)
- Neil R Smalheiser
- University of Illinois-Chicago, UIC Psychiatric Institute MC912, 1601 W, Taylor Street, Chicago, IL 60612, USA.
| |
Collapse
|
26
|
Message in a bottle: long-range retrograde signaling in the nervous system. Trends Cell Biol 2007; 17:519-28. [PMID: 18029183 DOI: 10.1016/j.tcb.2007.09.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 09/07/2007] [Accepted: 09/07/2007] [Indexed: 01/08/2023]
Abstract
In many regions of the nervous system, signals produced by target cells and surrounding glia or in response to in jury are received at axon terminals and then retrogradely propagated to cell bodies where they regulate gene transcription and other cellular processes required for development and adult function. The cellular and molecular mechanisms of axonal retrograde signaling in neurons have traditionally been studied in the context of survival signals provided by target-derived neurotrophic factors, in which signaling endosomes containing endocytosed ligand-receptor complexes and downstream effectors are retrogradely tra nsported by dynein motors. In recent years, this notion has been refined and additional mechanisms for long-range retrograde signaling in axons have been described. This article discusses some outstanding issues in the signaling endosome hypothesis as well as recent findings suggesting the existence of a variety of mechanisms for the retrograde propagation of signals in the nervous system.
Collapse
|
27
|
Echarte MM, Bruno L, Arndt-Jovin DJ, Jovin TM, Pietrasanta LI. Quantitative single particle tracking of NGF-receptor complexes: transport is bidirectional but biased by longer retrograde run lengths. FEBS Lett 2007; 581:2905-13. [PMID: 17543952 DOI: 10.1016/j.febslet.2007.05.041] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 05/08/2007] [Accepted: 05/08/2007] [Indexed: 01/11/2023]
Abstract
The retrograde transport of nerve growth factor (NGF) in neurite-like processes of living differentiated PC12 cells was studied using streptavidin-quantum dots (QDs) coupled to monobiotin-NGF. These reagents were active in differentiation, binding, internalization, and transport. Ten-35% of the QD-NGF-receptor complexes were mobile. Quantitative single particle tracking revealed a bidirectional step-like motion, requiring intact microtubules, with a net retrograde velocity of 0.054+/-0.020 microm/s. Individual runs had a mean velocity of approximately 0.15 microm/s at room temperature, and the run times were exponentially distributed. The photostability and brightness of QDs permit extended real-time analysis of individual QDbNGF- receptor complexes trafficking within neurites.
Collapse
Affiliation(s)
- María M Echarte
- Centro de Microscopías Avanzadas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Pabellón I, Ciudad Universitaria, Buenos Aires, Argentina
| | | | | | | | | |
Collapse
|
28
|
Abstract
UNLABELLED The view that lysosomes simply represent end organelles in the serial degradation of polymeric molecules derived from the cell surface and its interior has led to major misconceptions about the nature of lysosomal storage diseases and the pathogenic cascades that characterize them. Accordingly, lysosomal storage bodies are often considered 'inert', inducing cell dysfunction and death primarily through mechanical overcrowding of normal organelles or by other non-specific means leading to generalized cytotoxicity. However, modern studies of lysosomes and their component proteins provide evidence to support a far greater role for these organelles in cell metabolism. In intimate association with endosomal, autophagosomal and related vesicular systems, the greater lysosomal system can be conceptualized as a vital recycling centre that serves as a central metabolic coordinator, influencing literally every aspect of the cell, from signal transduction to regulation of gene expression. CONCLUSION This broader view of the role of lysosomes in cells not only provides insight into how single gene defects impacting on lysosomal function can result in the plethora of complex cellular transformations characteristic of these diseases, but also suggests new and innovative therapies that may hold considerable promise for ameliorating disease progression.
Collapse
Affiliation(s)
- Steven U Walkley
- Sidney Weisner Laboratory of Genetic Neurological Disease, Department of Neuroscience, Rose F. Kennedy Center for Research in Mental Retardation and Human Development, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| |
Collapse
|
29
|
Almeida CG, Takahashi RH, Gouras GK. Beta-amyloid accumulation impairs multivesicular body sorting by inhibiting the ubiquitin-proteasome system. J Neurosci 2006; 26:4277-88. [PMID: 16624948 PMCID: PMC6673997 DOI: 10.1523/jneurosci.5078-05.2006] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Increasing evidence links intraneuronal beta-amyloid (Abeta42) accumulation with the pathogenesis of Alzheimer's disease (AD). In Abeta precursor protein (APP) mutant transgenic mice and in human AD brain, progressive intraneuronal accumulation of Abeta42 occurs especially in multivesicular bodies (MVBs). We hypothesized that this impairs the MVB sorting pathway. We used the trafficking of the epidermal growth factor receptor (EGFR) and TrkB receptor to investigate the MVB sorting pathway in cultured neurons. We report that, during EGF stimulation, APP mutant neurons demonstrated impaired inactivation, degradation, and ubiquitination of EGFR. EGFR degradation is dependent on translocation from MVB outer to inner membranes, which is regulated by the ubiquitin-proteasome system (UPS). We provide evidence that Abeta accumulation in APP mutant neurons inhibits the activities of the proteasome and deubiquitinating enzymes. These data suggest a mechanism whereby Abeta accumulation in neurons impairs the MVB sorting pathway via the UPS in AD.
Collapse
|
30
|
Albrecht D, García L, Cartier L, Kettlun AM, Vergara C, Collados L, Valenzuela MA. Trophic factors in cerebrospinal fluid and spinal cord of patients with tropical spastic paraparesis, HIV, and Creutzfeldt-Jakob disease. AIDS Res Hum Retroviruses 2006; 22:248-54. [PMID: 16545011 DOI: 10.1089/aid.2006.22.248] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
HTLV-1-associated myelopathy/tropical spastic paraparesis (TSP/HAM) is a chronic CNS disease characterized by axomyelinic degeneration of the long axons of corticospinal tracts. Levels of NGF, NT-3, NT-4/5, BDNF, GDNF, CNTF, and FGF-2 were measured in the cerebrospinal fluid (CSF) of 21 TSP/HAM patients and 20 controls. NGF, BDNF, and FGF-2 levels were also determined in 19 patients with HIV motor cognitive motor syndrome, and in 21 subjects diagnosed with Creutzfeldt Jakob disease (CJD). No significant differences were detected in the concentrations of NGF, BDNF, NT-3, NT-4/5, GDNF, and CNTF in the CSF between TSP/HAM patients and controls. FGF-2 was significantly lower in the CSF of the three groups of patients compared with controls; the HIV group exhibited the lowest values. HIV patients differed from TSP/HAM in their significantly higher levels of NGF and lower levels of BDNF and FGF-2, whereas CJD patients differed only in their higher levels of NGF. Immunohistochemical studies were done of trophic factors (NGF and FGF-2) and neurotrophin receptors (trkA and p75) in spinal cord and motor cortical areas from anatomopathological cases of TSP/HAM. Results indicated that NGF is expressed in motoneurons and oligodendrocytes of the posterior column of the spinal cord. FGF-2 was detected in motoneurons and spinal cord vessels. p75 receptor was detected in cortical neurons. The absence of a significant change in the trophic factor levels in TSP/HAM may be attributed to a selective axonal lesion in a slow process.
Collapse
Affiliation(s)
- David Albrecht
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | | | | | | | | | | | | |
Collapse
|
31
|
Valdez G, Akmentin W, Philippidou P, Kuruvilla R, Ginty DD, Halegoua S. Pincher-mediated macroendocytosis underlies retrograde signaling by neurotrophin receptors. J Neurosci 2006; 25:5236-47. [PMID: 15917464 PMCID: PMC6724820 DOI: 10.1523/jneurosci.5104-04.2005] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Retrograde signaling by neurotrophins is crucial for regulating neuronal phenotype and survival. The mechanism responsible for retrograde signaling has been elusive, because the molecular entities that propagate Trk receptor tyrosine kinase signals from the nerve terminal to the soma have not been defined. Here, we show that the membrane trafficking protein Pincher defines the primary pathway responsible for neurotrophin retrograde signaling in neurons. By both immunofluorescence confocal and immunoelectron microscopy, we find that Pincher mediates the formation of newly identified clathrin-independent macroendosomes for Trk receptors in soma, axons, and dendrites. Trk macroendosomes are derived from plasma membrane ruffles and subsequently processed to multivesicular bodies. Pincher similarly mediates macroendocytosis for NGF (TrkA) and BDNF (TrkB) in both peripheral (sympathetic) and central (hippocampal) neurons. A unique feature of Pincher-Trk endosomes is refractoriness to lysosomal degradation, which ensures persistent signaling through a critical effector of retrograde survival signaling, Erk5 (extracellular signal-regulated kinase 5). Using sympathetic neurons grown in chamber cultures, we find that block of Pincher function, which prevents Trk macroendosome formation, eliminates retrogradely signaled neuronal survival. Pincher is the first distinguishing molecular component of a novel mechanistic pathway for endosomal signaling in neurons.
Collapse
MESH Headings
- Animals
- Animals, Newborn
- Blotting, Western/methods
- Cell Survival/physiology
- Cells, Cultured
- Diagnostic Imaging/methods
- Dynamins/metabolism
- Embryo, Mammalian
- Endocytosis/physiology
- Endosomes/metabolism
- Endosomes/ultrastructure
- Epidermal Growth Factor/metabolism
- Fluorescent Antibody Technique/methods
- Green Fluorescent Proteins/metabolism
- Hippocampus/cytology
- Lysosomes/metabolism
- Lysosomes/ultrastructure
- Microscopy, Confocal/methods
- Microscopy, Immunoelectron/methods
- Mitogen-Activated Protein Kinase 7/metabolism
- Molecular Biology/methods
- Nerve Tissue Proteins/physiology
- Neurons/physiology
- Neurons/ultrastructure
- Protein Transport/physiology
- RNA Interference/physiology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Receptor, trkA/metabolism
- Receptors, Nerve Growth Factor/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Signal Transduction/physiology
- Superior Cervical Ganglion/cytology
- Transfection/methods
Collapse
Affiliation(s)
- Gregorio Valdez
- Department of Neurobiology and Behavior, Center for Brain and Spinal Cord Research, State University of New York at Stony Brook, Stony Brook, New York 11794-5230, USA
| | | | | | | | | | | |
Collapse
|
32
|
Gouras GK, Almeida CG, Takahashi RH. Intraneuronal Abeta accumulation and origin of plaques in Alzheimer's disease. Neurobiol Aging 2006; 26:1235-44. [PMID: 16023263 DOI: 10.1016/j.neurobiolaging.2005.05.022] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 05/25/2005] [Accepted: 05/27/2005] [Indexed: 10/25/2022]
Abstract
Plaques are a defining neuropathological hallmark of Alzheimer's disease (AD) and the major constituent of plaques, the beta-amyloid peptide (Abeta), is considered to play an important role in the pathophysiology of AD. But the biological origin of Abeta plaques and the mechanism whereby Abeta is involved in pathogenesis have been unknown. Abeta plaques were thought to form from the gradual accumulation and aggregation of secreted Abeta in the extracellular space. More recently, the accumulation of Abeta has been demonstrated to occur within neurons with AD pathogenesis. Moreover, intraneuronal Abeta accumulation has been reported to be critical in the synaptic dysfunction, cognitive dysfunction and the formation of plaques in AD. Here we provide a historical overview on the origin of plaques and a discussion on potential biological and therapeutic implications of intraneuronal Abeta accumulation for AD.
Collapse
Affiliation(s)
- Gunnar K Gouras
- Laboratory of Alzheimer's disease Neurobiology, Department of Neurology & Neuroscience, Weill Medical College of Cornell University, 525 East 68th Street, New York, NY 10021, USA.
| | | | | |
Collapse
|
33
|
Howe CL. Modeling the signaling endosome hypothesis: why a drive to the nucleus is better than a (random) walk. Theor Biol Med Model 2005; 2:43. [PMID: 16236165 PMCID: PMC1276819 DOI: 10.1186/1742-4682-2-43] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 10/19/2005] [Indexed: 01/01/2023] Open
Abstract
Background Information transfer from the plasma membrane to the nucleus is a universal cell biological property. Such information is generally encoded in the form of post-translationally modified protein messengers. Textbook signaling models typically depend upon the diffusion of molecular signals from the site of initiation at the plasma membrane to the site of effector function within the nucleus. However, such models fail to consider several critical constraints placed upon diffusion by the cellular milieu, including the likelihood of signal termination by dephosphorylation. In contrast, signaling associated with retrogradely transported membrane-bounded organelles such as endosomes provides a dephosphorylation-resistant mechanism for the vectorial transmission of molecular signals. We explore the relative efficiencies of signal diffusion versus retrograde transport of signaling endosomes. Results Using large-scale Monte Carlo simulations of diffusing STAT-3 molecules coupled with probabilistic modeling of dephosphorylation kinetics we found that predicted theoretical measures of STAT-3 diffusion likely overestimate the effective range of this signal. Compared to the inherently nucleus-directed movement of retrogradely transported signaling endosomes, diffusion of STAT-3 becomes less efficient at information transfer in spatial domains greater than 200 nanometers from the plasma membrane. Conclusion Our model suggests that cells might utilize two distinct information transmission paradigms: 1) fast local signaling via diffusion over spatial domains on the order of less than 200 nanometers; 2) long-distance signaling via information packets associated with the cytoskeletal transport apparatus. Our model supports previous observations suggesting that the signaling endosome hypothesis is a subset of a more general hypothesis that the most efficient mechanism for intracellular signaling-at-a-distance involves the association of signaling molecules with molecular motors that move along the cytoskeleton. Importantly, however, cytoskeletal association of membrane-bounded complexes containing ligand-occupied transmembrane receptors and downstream effector molecules provides the ability to regenerate signals at any point along the transmission path. We conclude that signaling endosomes provide unique information transmission properties relevant to all cell architectures, and we propose that the majority of relevant information transmitted from the plasma membrane to the nucleus will be found in association with organelles of endocytic origin.
Collapse
Affiliation(s)
- Charles L Howe
- Departments of Neuroscience and Neurology, Mayo Clinic College of Medicine, Guggenheim 442-C, Rochester, MN 55905, USA.
| |
Collapse
|
34
|
Yano H, Chao MV. Biochemical Characterization of Intracellular Membranes Bearing Trk Neurotrophin Receptors. Neurochem Res 2005; 30:767-77. [PMID: 16187212 DOI: 10.1007/s11064-005-6870-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2005] [Indexed: 01/19/2023]
Abstract
Neurotrophin receptor trafficking plays an important role in directing cellular communication in developing as well as mature neurons. However, little is known about the requirements for intracellular localization of the neurotrophin receptors in neurons. To isolate the subcellular membrane compartments containing the Trk neurotrophin receptor, we performed biochemical subcellular fractionation experiments using primary cortical neurons and rat PC12 pheochromocytoma cells. By differential centrifugation and density gradient centrifugation, we have isolated Trk-bearing compartments, suggesting distinct membranous localization of Trk receptors. A number of Trk-interacting proteins, such as GIPC and dynein light chain Tctex-1 were found in these fractions. Additionally, membranes enriched in phosphorylated activated forms of Trk receptors were found upon ligand treatment in primary neurons and PC12 cells. Interestingly, density gradient centrifugation experiments showed that Trk receptors from PC12 cells are present in heavy membrane fractions, while Trk from primary neurons are fractionated in lighter membrane fractions. These results suggest that the intracellular membrane localization of Trk can differ according to cell type. Taken together, these biochemical approaches allowed separation of distinct Trk-bearing membrane pools, which may be involved in different functions of neurotrophin receptor signaling and trafficking.
Collapse
Affiliation(s)
- Hiroko Yano
- Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
| | | |
Collapse
|
35
|
Perlson E, Hanz S, Ben-Yaakov K, Segal-Ruder Y, Seger R, Fainzilber M. Vimentin-dependent spatial translocation of an activated MAP kinase in injured nerve. Neuron 2005; 45:715-26. [PMID: 15748847 DOI: 10.1016/j.neuron.2005.01.023] [Citation(s) in RCA: 389] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 11/16/2004] [Accepted: 01/14/2005] [Indexed: 01/26/2023]
Abstract
How are phosphorylated kinases transported over long intracellular distances, such as in the case of axon to cell body signaling after nerve injury? Here, we show that the MAP kinases Erk1 and Erk2 are phosphorylated in sciatic nerve axoplasm upon nerve injury, concomitantly with the production of soluble forms of the intermediate filament vimentin by local translation and calpain cleavage in axoplasm. Vimentin binds phosphorylated Erks (pErk), thus linking pErk to the dynein retrograde motor via direct binding of vimentin to importin beta. Injury-induced Elk1 activation and neuronal regeneration are inhibited or delayed in dorsal root ganglion neurons from vimentin null mice, and in rats treated with a MEK inhibitor or with a peptide that prevents pErk-vimentin binding. Thus, soluble vimentin enables spatial translocation of pErk by importins and dynein in lesioned nerve.
Collapse
Affiliation(s)
- Eran Perlson
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
| | | | | | | | | | | |
Collapse
|
36
|
Schiavo G, Chao MV. Motors, adaptors, and receptors: key elements of neuronal transport. JOURNAL OF NEUROBIOLOGY 2004; 58:161-3. [PMID: 14704948 DOI: 10.1002/neu.10325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Giampietro Schiavo
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, United Kingdom.
| | | |
Collapse
|