scholarly journals Neurotrophin-regulated signalling pathways

2006 ◽  
Vol 361 (1473) ◽  
pp. 1545-1564 ◽  
Author(s):  
Louis F Reichardt
Keyword(s):  
Nervous System ◽  
Map Kinases ◽  
Sympathetic Neurons ◽  
Axon Growth ◽  
Synaptic Function ◽  
Neurotrophin Receptor ◽  
Signalling Pathways ◽  
Tumour Necrosis Factor Receptor ◽  
Trk Receptors ◽  
Cell Fate Decisions

Neurotrophins are a family of closely related proteins that were identified initially as survival factors for sensory and sympathetic neurons, and have since been shown to control many aspects of survival, development and function of neurons in both the peripheral and the central nervous systems. Each of the four mammalian neurotrophins has been shown to activate one or more of the three members of the tropomyosin-related kinase (Trk) family of receptor tyrosine kinases (TrkA, TrkB and TrkC). In addition, each neurotrophin activates p75 neurotrophin receptor (p75NTR), a member of the tumour necrosis factor receptor superfamily. Through Trk receptors, neurotrophins activate Ras, phosphatidyl inositol-3 (PI3)-kinase, phospholipase C-γ1 and signalling pathways controlled through these proteins, such as the MAP kinases. Activation of p75NTR results in activation of the nuclear factor-κB (NF-κB) and Jun kinase as well as other signalling pathways. Limiting quantities of neurotrophins during development control the number of surviving neurons to ensure a match between neurons and the requirement for a suitable density of target innervation. The neurotrophins also regulate cell fate decisions, axon growth, dendrite growth and pruning and the expression of proteins, such as ion channels, transmitter biosynthetic enzymes and neuropeptide transmitters that are essential for normal neuronal function. Continued presence of the neurotrophins is required in the adult nervous system, where they control synaptic function and plasticity, and sustain neuronal survival, morphology and differentiation. They also have additional, subtler roles outside the nervous system. In recent years, three rare human genetic disorders, which result in deleterious effects on sensory perception, cognition and a variety of behaviours, have been shown to be attributable to mutations in brain-derived neurotrophic factor and two of the Trk receptors.

scholarly journals T-type Ca 2+ channels are required for enhanced sympathetic axon growth by TNFα reverse signalling

Open Biology ◽  
2017 ◽  
Vol 7 (1) ◽  
pp. 160288 ◽  
Author(s):  
Lilian Kisiswa ◽  
Clara Erice ◽  
Laurent Ferron ◽  
Sean Wyatt ◽  
Catarina Osório ◽  
...  
Keyword(s):  
Sympathetic Neurons ◽  
Sympathetic Innervation ◽  
Axon Growth ◽  
Tumour Necrosis Factor Receptor ◽  
Kinase C ◽  
Cultured Sympathetic Neurons ◽  
Sympathetic Axon ◽  
Pkc Activation ◽  
Cell Somata ◽  
Necrosis Factor

Tumour necrosis factor receptor 1 (TNFR1)-activated TNFα reverse signalling, in which membrane-integrated TNFα functions as a receptor for TNFR1, enhances axon growth from developing sympathetic neurons and plays a crucial role in establishing sympathetic innervation. Here, we have investigated the link between TNFα reverse signalling and axon growth in cultured sympathetic neurons. TNFR1-activated TNFα reverse signalling promotes Ca 2+ influx, and highly selective T-type Ca 2+ channel inhibitors, but not pharmacological inhibitors of L-type, N-type and P/Q-type Ca 2+ channels, prevented enhanced axon growth. T-type Ca 2+ channel-specific inhibitors eliminated Ca 2+ spikes promoted by TNFα reverse signalling in axons and prevented enhanced axon growth when applied locally to axons, but not when applied to cell somata. Blocking action potential generation did not affect the effect of TNFα reverse signalling on axon growth, suggesting that propagated action potentials are not required for enhanced axon growth. TNFα reverse signalling enhanced protein kinase C (PKC) activation, and pharmacological inhibition of PKC prevented the axon growth response. These results suggest that TNFα reverse signalling promotes opening of T-type Ca 2+ channels along sympathetic axons, which is required for enhanced axon growth.

Mechanisms of neurotrophin receptor signalling

2006 ◽  
Vol 34 (4) ◽  
pp. 607-611 ◽  
Author(s):  
N. Zampieri ◽  
M.V. Chao
Keyword(s):  
Neurotrophin Receptor ◽  
General Mechanism ◽  
Tumour Necrosis Factor Receptor ◽  
Trk Receptors ◽  
Neuroprotective Effects ◽  
Trk Receptor ◽  
Src Homology ◽  
Membrane Spanning ◽  
G Protein Coupled ◽  
P75 Receptor

Regulation of cell survival decisions and neuronal plasticity by neurotrophins are mediated by two classes of receptors, Trks (tropomyosin receptor kinases) and p75, the first discovered member of the tumour necrosis factor receptor superfamily. The p75 receptor participates with the TrkA receptor in the formation of high-affinity nerve growth factor-binding sites to promote survival under limiting concentrations of neurotrophins. Activation of Trk receptors leads to increased phosphorylation of Shc (Src homology and collagen homology), phospholipase C-γ and novel adaptor molecules, such as the ARMS (ankyrin-rich membrane spanning)/Kidins220 protein. Small ligands that interact with G-protein-coupled receptors can also activate Trk receptor kinase activity. Transactivation of Trk receptors and their downstream signalling pathways raise the possibility of using small molecules to elicit neuroprotective effects for the treatment of neurodegenerative diseases. Like amyloid precursor protein and Notch, p75 is a substrate for γ-secretase cleavage. The p75 receptor undergoes an α-secretase-mediated release of the extracellular domain followed by a γ-secretase-mediated intramembrane cleavage. Cleavage of p75 may represent a general mechanism for transmitting signals as an independent receptor and as a co-receptor for other signalling systems.

scholarly journals p75-deficient embryonic dorsal root sensory and neonatal sympathetic neurons display a decreased sensitivity to NGF

Development ◽  
1994 ◽  
Vol 120 (4) ◽  
pp. 1027-1033 ◽  
Author(s):  
K.F. Lee ◽  
A.M. Davies ◽  
R. Jaenisch
Keyword(s):  
Nervous System ◽  
Peripheral Nervous System ◽  
Neural Development ◽  
Dorsal Root ◽  
Sympathetic Neurons ◽  
Mutant Mice ◽  
Neurotrophin Receptor ◽  
Cervical Ganglion ◽  
Response Specificity

To understand the role of low-affinity neurotrophin receptor p75 in neural development, we previously generated mice carrying a null mutation in the p75 locus (Lee, K. F., Li, E., Huber, L. J., Landis, S. C., Sharpe, A. H., Chao, M. V. and Jaenisch, R. (1992) Cell 69, 737–749). To elucidate the mechanisms leading to deficits in the peripheral nervous system in p75 mutant mice, we have employed dissociated cultures to examine the responses of p75-deficient dorsal root ganglion (DRG) and superior cervical ganglion (SCG) neurons to different neurotrophins. We found that p75-deficient DRG and SCG neurons displayed a 2- to 3-fold decreased sensitivity to NGF at embryonic day 15 (E15) and postnatal day 3 (P3), respectively, ages that coincide with the peak of naturally occurring cell death. Furthermore, while p75-deficient E15 DRG neurons did not change their response specificity to BDNF, NT-3, and NT-4/5, P3 SCG neurons became more responsive to NT-3 at higher concentrations (nanomolar ranges). These results may help explain the deficits in the peripheral nervous system in p75 mutant mice and provide evidence that p75 can modulate neurotrophin sensitivity in some neurons.

scholarly journals Rho activation patterns after spinal cord injury and the role of activated Rho in apoptosis in the central nervous system

2003 ◽  
Vol 162 (2) ◽  
pp. 233-243 ◽  
Author(s):  
Catherine I. Dubreuil ◽  
Matthew J. Winton ◽  
Lisa McKerracher
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Spinal Cord Injury ◽  
Nervous System ◽  
Axon Growth ◽  
Neurotrophin Receptor ◽  
P75 Neurotrophin Receptor ◽  
Cord Injury ◽  
The Central Nervous System

Growth inhibitory proteins in the central nervous system (CNS) block axon growth and regeneration by signaling to Rho, an intracellular GTPase. It is not known how CNS trauma affects the expression and activation of RhoA. Here we detect GTP-bound RhoA in spinal cord homogenates and report that spinal cord injury (SCI) in both rats and mice activates RhoA over 10-fold in the absence of changes in RhoA expression. In situ Rho-GTP detection revealed that both neurons and glial cells showed Rho activation at SCI lesion sites. Application of a Rho antagonist (C3–05) reversed Rho activation and reduced the number of TUNEL-labeled cells by ∼50% in both injured mouse and rat, showing a role for activated Rho in cell death after CNS injury. Next, we examined the role of the p75 neurotrophin receptor (p75NTR) in Rho signaling. After SCI, an up-regulation of p75NTR was detected by Western blot and observed in both neurons and glia. Treatment with C3–05 blocked the increase in p75NTR expression. Experiments with p75NTR-null mutant mice showed that immediate Rho activation after SCI is p75NTR dependent. Our results indicate that blocking overactivation of Rho after SCI protects cells from p75NTR-dependent apoptosis.

Postsynaptic neuronal geometry and synaptic effectiveness

1987 ◽  
Vol 45 ◽  
pp. 690-697
Author(s):  
C.J. Wilson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Function ◽  
Postsynaptic Neuron ◽  
Synaptic Inputs ◽  
Partial Analysis ◽  
Postsynaptic Cell ◽  
Neuronal Geometry ◽  
The Relationship ◽  
Complex Scale

Most central nervous system neurons receive synaptic input from hundreds or thousands of other neurons, and the computational function of such neurons results from the interactions of inputs on a large and complex scale. In most situations that have yielded to a partial analysis, the synaptic inputs to a neuron are not alike in function, but rather belong to distinct categories that differ qualitatively in the nature of their effect on the postsynaptic cell, and quantitatively in the strength of their influence. Many factors have been demonstrated to contribute to synaptic function, but one of the simplest and best known of these is the geometry of the postsynaptic neuron. The fundamental nature of the relationship between neuronal shape and synaptic effectiveness was established on theoretical grounds prior to its experimental verification.

Glial Cells in the Auditory Brainstem

2018 ◽  
pp. 680-706
Author(s):  
Giedre Milinkeviciute ◽  
Karina S. Cramer
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Sound Localization ◽  
Auditory Brainstem ◽  
Synaptic Function ◽  
System Function ◽  
Auditory Neurons ◽  
System P ◽  
The Central Nervous System ◽  
Nervous System Function

The auditory brainstem carries out sound localization functions that require an extraordinary degree of precision. While many of the specializations needed for these functions reside in auditory neurons, additional adaptations are made possible by the functions of glial cells. Astrocytes, once thought to have mainly a supporting role in nervous system function, are now known to participate in synaptic function. In the auditory brainstem, they contribute to development of specialized synapses and to mature synaptic function. Oligodendrocytes play critical roles in regulating timing in sound localization circuitry. Microglia enter the central nervous system early in development, and also have important functions in the auditory system’s response to injury. This chapter highlights the unique functions of these non-neuronal cells in the auditory system.

scholarly journals The Role of Lipids, Lipid Metabolism and Ectopic Lipid Accumulation in Axon Growth, Regeneration and Repair after CNS Injury and Disease

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1078
Author(s):  
Debasish Roy ◽  
Andrea Tedeschi
Keyword(s):  
Nervous System ◽  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
Axon Regeneration ◽  
Axon Growth ◽  
The Body ◽  
Cns Repair ◽  
Cord Injury ◽  
Cns Trauma

Axons in the adult mammalian nervous system can extend over formidable distances, up to one meter or more in humans. During development, axonal and dendritic growth requires continuous addition of new membrane. Of the three major kinds of membrane lipids, phospholipids are the most abundant in all cell membranes, including neurons. Not only immature axons, but also severed axons in the adult require large amounts of lipids for axon regeneration to occur. Lipids also serve as energy storage, signaling molecules and they contribute to tissue physiology, as demonstrated by a variety of metabolic disorders in which harmful amounts of lipids accumulate in various tissues through the body. Detrimental changes in lipid metabolism and excess accumulation of lipids contribute to a lack of axon regeneration, poor neurological outcome and complications after a variety of central nervous system (CNS) trauma including brain and spinal cord injury. Recent evidence indicates that rewiring lipid metabolism can be manipulated for therapeutic gain, as it favors conditions for axon regeneration and CNS repair. Here, we review the role of lipids, lipid metabolism and ectopic lipid accumulation in axon growth, regeneration and CNS repair. In addition, we outline molecular and pharmacological strategies to fine-tune lipid composition and energy metabolism in neurons and non-neuronal cells that can be exploited to improve neurological recovery after CNS trauma and disease.

scholarly journals RNAseq shows an all-pervasive day-night rhythm in the transcriptome of the pacemaker of the heart

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanwen Wang ◽  
Cali Anderson ◽  
Halina Dobrzynski ◽  
George Hart ◽  
Alicia D’Souza ◽  
...  
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Circadian Clock ◽  
Sick Sinus Syndrome ◽  
Sinus Node ◽  
Signalling Pathways ◽  
Resting Heart Rate ◽  
Ion Channel Regulation ◽  
Channel Regulation ◽  
Physiological Systems

AbstractPhysiological systems vary in a day-night manner anticipating increased demand at a particular time. Heart is no exception. Cardiac output is primarily determined by heart rate and unsurprisingly this varies in a day-night manner and is higher during the day in the human (anticipating increased day-time demand). Although this is attributed to a day-night rhythm in post-translational ion channel regulation in the heart’s pacemaker, the sinus node, by the autonomic nervous system, we investigated whether there is a day-night rhythm in transcription. RNAseq revealed that ~ 44% of the sinus node transcriptome (7134 of 16,387 transcripts) has a significant day-night rhythm. The data revealed the oscillating components of an intrinsic circadian clock. Presumably this clock (or perhaps the master circadian clock in the suprachiasmatic nucleus) is responsible for the rhythm observed in the transcriptional machinery, which in turn is responsible for the rhythm observed in the transcriptome. For example, there is a rhythm in transcripts responsible for the two principal pacemaker mechanisms (membrane and Ca2+ clocks), transcripts responsible for receptors and signalling pathways known to control pacemaking, transcripts from genes identified by GWAS as determinants of resting heart rate, and transcripts from genes responsible for familial and acquired sick sinus syndrome.

scholarly journals The tumor suppressor HHEX inhibits axon growth when prematurely expressed in developing central nervous system neurons

2015 ◽  
Vol 68 ◽  
pp. 272-283 ◽  
Author(s):  
Matthew T. Simpson ◽  
Ishwariya Venkatesh ◽  
Ben L. Callif ◽  
Laura K. Thiel ◽  
Denise M. Coley ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Tumor Suppressor ◽  
Axon Growth

Analysis of the development of the nervous system of the zebrafish, Brachydanio rerio

Development ◽  
1968 ◽  
Vol 19 (2) ◽  
pp. 109-119
Author(s):  
Judith Shulman Weis
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Neural Crest ◽  
Neural Tube ◽  
Sympathetic Neurons ◽  
Dorsal Surface ◽  
Teleost Fishes ◽  
Brachydanio Rerio ◽  
Solid Structure ◽  
Derivatives Of

In teleost fishes, unlike many other vertebrates, the spinal cord originates as a solid structure, the neural keel, which subsequently hollows out. Unlike vertebrates in which the neural tube is formed from neural folds, and where the neural crest arises from wedge-shaped masses of tissue connecting the neural tube to the general ectoderm, teleosts do not possess a clear morphological neural crest. Initially, the dorsal surface of the keel is broadly attached to the ectoderm as described by Shepard (1961). As the neural primordia become larger and more discrete, the region of attachment narrows, and cells become loose (the ‘loose crest stage’). These cells represent the neural crest. Subsequently they begin to migrate and to differentiate into the various derivatives of neural crest. Both sensory and sympathetic neurons arise from neural crest. At the time of their migration the cells are not morphologically distinguishable.

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