keyword
MENU ▼
Read by QxMD icon Read
search

axon initial segment

keyword
https://www.readbyqxmd.com/read/28534438/the-axonal-cytoskeleton-and-the-assembly-of-nodes-of-ranvier
#1
Aniket Ghosh, Diane L Sherman, Peter J Brophy
Vertebrate nervous systems rely on rapid nerve impulse transmission to support their complex functions. Fast conduction depends on ensheathment of nerve axons by myelin-forming glia and the clustering of high concentrations of voltage-gated sodium channels (Nav) in the axonal gaps between myelinated segments. These gaps are the nodes of Ranvier. Depolarization of the axonal membrane initiates the action potential responsible for impulse transmission, and the Nav help ensure that this is restricted to nodes...
May 1, 2017: Neuroscientist: a Review Journal Bringing Neurobiology, Neurology and Psychiatry
https://www.readbyqxmd.com/read/28533267/the-kv1-associated-molecules-tag-1-and-caspr2-are-selectively-targeted-to-axon-initial-segment-in-hippocampal-neurons
#2
Delphine Pinatel, Bruno Hivert, Margaux Saint-Martin, Nelly Noraz, Maria Savvaki, Domna Karagogeos, Catherine Faivre-Sarrailh
Caspr2 and TAG-1 are cell adhesion molecules (CAMs) associated with the voltage-gated potassium channels Kv1.1/1.2 at regions controlling axonal excitability, the axon initial segment (AIS) and juxtaparanodes of myelinated axons. The distribution of Kv1 at juxtaparanodes requires axo-glial contacts mediated by Caspr2 and TAG-1. In the present study, we showed that TAG-1 strongly co-localizes with Kv1.2 at the AIS of cultured hippocampal neurons whereas Caspr2 is uniformly expressed along the axolemma. Live-cell imaging revealed that Caspr2 and TAG-1 are sorted together in axonal transport vesicles...
May 22, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28522735/d3-receptors-regulate-excitability-in-a-unique-class-of-prefrontal-pyramidal-cell
#3
Rebecca L Clarkson, Alayna T Liptak, Steven M Gee, Vikaas S Sohal, Kevin J Bender
The D3 dopamine receptor, a member of the Gi-coupled D2-family of dopamine receptors, is expressed throughout limbic circuits affected in neuropsychiatric disorders, including prefrontal cortex. These receptors are important for prefrontal executive function, as pharmacological and genetic manipulations that affect prefrontal D3 receptors alter anxiety, social interaction, and reversal learning. And yet, the mechanisms by which D3 receptors regulate prefrontal circuits, and whether D3 receptors regulate specific prefrontal subnetworks, remain unknown...
May 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28469558/intracellular-fibroblast-growth-factor-14-emerging-risk-factor-for-brain-disorders
#4
REVIEW
Jessica Di Re, Paul A Wadsworth, Fernanda Laezza
The finely tuned regulation of neuronal firing relies on the integrity of ion channel macromolecular complexes. Minimal disturbances of these tightly regulated networks can lead to persistent maladaptive plasticity of brain circuitry. The intracellular fibroblast growth factor 14 (FGF14) belongs to the nexus of proteins interacting with voltage-gated Na+ (Nav) channels at the axonal initial segment. Through isoform-specific interactions with the intracellular C-terminal tail of neuronal Nav channels (Nav1.1, Nav1...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28452088/myosin-ii-activity-is-required-for-structural-plasticity-at-the-axon-initial-segment
#5
Mark D Evans, Candida Tufo, Adna S Dumitrescu, Matthew S Grubb
In neurons, axons possess a molecularly defined and highly organised proximal region - the axon initial segment (AIS) - that is a key regulator of both electrical excitability and cellular polarity. Despite existing as a large, dense structure with specialised cytoskeletal architecture, the AIS is surprisingly plastic, with sustained alterations in neuronal activity bringing about significant alterations to its position, length or molecular composition. However, although the upstream activity-dependent signalling pathways that lead to such plasticity have begun to be elucidated, the downstream mechanisms that produce structural changes at the AIS are completely unknown...
April 27, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28450535/sodium-channel-nav1-8-underlies-ttx-resistant-axonal-action-potential-conduction-in-somatosensory-c-fibers-of-distal-cutaneous-nerves
#6
Amanda H Klein, Alina Vyshnevska, Timothy V Hartke, Roberto De Col, Joseph L Mankowski, Brian Turnquist, Frank Bosmans, Peter W Reeh, Martin Schmelz, Richard W Carr, Matthias Ringkamp
Voltage-gated sodium (NaV) channels are responsible for the initiation and conduction of action potentials within primary afferents. The nine NaV channel isoforms recognized in mammals are often functionally divided into tetrodotoxin (TTX)-sensitive (TTX-s) channels (NaV1.1-NaV1.4, NaV1.6-NaV1.7) that are blocked by nanomolar concentrations and TTX-resistant (TTX-r) channels (NaV1.8 and NaV1.9) inhibited by millimolar concentrations, with NaV1.5 having an intermediate toxin sensitivity. For small-diameter primary afferent neurons, it is unclear to what extent different NaV channel isoforms are distributed along the peripheral and central branches of their bifurcated axons...
May 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28441389/the-basis-of-sharp-spike-onset-in-standard-biophysical-models
#7
Maria Telenczuk, Bertrand Fontaine, Romain Brette
In most vertebrate neurons, spikes initiate in the axonal initial segment (AIS). When recorded in the soma, they have a surprisingly sharp onset, as if sodium (Na) channels opened abruptly. The main view stipulates that spikes initiate in a conventional manner at the distal end of the AIS, then progressively sharpen as they backpropagate to the soma. We examined the biophysical models used to substantiate this view, and we found that spikes do not initiate through a local axonal current loop that propagates along the axon, but through a global current loop encompassing the AIS and soma, which forms an electrical dipole...
2017: PloS One
https://www.readbyqxmd.com/read/28440877/bdnf-nt3-regulate-ais-location-and-affect-neuronal-excitability-in-cultured-hippocampal-neurons
#8
Yu Guo, Zi-Jun Su, Yi-Kun Chen, Zhen Chai
Plasticity of the axon initial segment (AIS) has aroused great interest in recent years because it regulates action potential initiation and neuronal excitability. AIS plasticity manifests as modulation of ion channels or variation in AIS structure. However, the mechanisms underlying structural plasticity of the AIS are not well understood. Here, we combined immunofluorescence, patch-clamp recordings, and pharmacological methods in cultured hippocampal neurons to investigate the factors participating in AIS structural plasticity during development...
April 25, 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/28436546/corrigendum-the-impact-of-early-environmental-interventions-on-structural-plasticity-of-the-axon-initial-segment-in-neocortex-m-nozari-t-suzuki-m-g-p-rosa-k-yamakawa-and-n-atapour
#9
(no author information available yet)
No abstract text is available yet for this article.
April 24, 2017: Developmental Psychobiology
https://www.readbyqxmd.com/read/28426968/map2-defines-a-pre-axonal-filtering-zone-to-regulate-kif1-versus-kif5-dependent-cargo-transport-in-sensory-neurons
#10
Laura F Gumy, Eugene A Katrukha, Ilya Grigoriev, Dick Jaarsma, Lukas C Kapitein, Anna Akhmanova, Casper C Hoogenraad
Polarized cargo transport is essential for neuronal function. However, the minimal basic components required for selective cargo sorting and distribution in neurons remain elusive. We found that in sensory neurons the axon initial segment is largely absent and that microtubule-associated protein 2 (MAP2) defines the cargo-filtering zone in the proximal axon. Here, MAP2 directs axonal cargo entry by coordinating the activities of molecular motors. We show that distinct kinesins differentially regulate cargo velocity: kinesin-3 drives fast axonal cargo trafficking, while kinesin-1 slows down axonal cargo transport...
April 19, 2017: Neuron
https://www.readbyqxmd.com/read/28424590/geometrical-determinants-of-neuronal-actin-waves
#11
Caterina Tomba, Céline Braïni, Ghislain Bugnicourt, Floriane Cohen, Benjamin M Friedrich, Nir S Gov, Catherine Villard
Hippocampal neurons produce in their early stages of growth propagative, actin-rich dynamical structures called actin waves. The directional motion of actin waves from the soma to the tip of neuronal extensions has been associated with net forward growth, and ultimately with the specification of neurites into axon and dendrites. Here, geometrical cues are used to control actin wave dynamics by constraining neurons on adhesive stripes of various widths. A key observable, the average time between the production of consecutive actin waves, or mean inter-wave interval (IWI), was identified...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28411148/behavioural-characterization-of-ankyring-deficient-mice-a-model-for-ank3-related-disorders
#12
I M van der Werf, D Van Dam, S Missault, B Yalcin, P P De Deyn, G Vandeweyer, R F Kooy
ANK3 encodes AnkyrinG (AnkG), a member of the Ankyrin family that is expressed in several different isoforms in many tissues. A unique serine-rich domain and tail domain in the two largest isoforms of AnkG (270 and 480kDa), restrict AnkG to the axon initial segment and nodes of Ranvier of myelinated neurons. At these sites, AnkG is a master regulator, coordinating the strict clustering of components necessary for proper action potential initiation and propagation along the axon. These components include voltage-gated sodium channels, potassium channels and members of the L1 cell adhesion molecule family...
April 11, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28331203/the-role-of-axonal-kv1-channels-in-ca3-pyramidal-cell-excitability
#13
Sylvain Rama, Mickael Zbili, Aurélie Fékété, Mónica Tapia, Maria José Benitez, Norah Boumedine, Juan José Garrido, Dominique Debanne
Axonal ion channels control spike initiation and propagation along the axon and determine action potential waveform. We show here that functional suppression of axonal Kv1 channels with local puff of dendrotoxin (DTx), laser or mechanical axotomy significantly increased excitability measured in the cell body. Importantly, the functional effect of DTx puffing or axotomy was not limited to the axon initial segment but was also seen on axon collaterals. In contrast, no effects were observed when DTx was puffed on single apical dendrites or after single dendrotomy...
March 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28331094/herpes-simplex-virus-ge-gi-and-us9-promote-both-envelopment-and-sorting-of-virus-particles-in-the-cytoplasm-of-neurons-two-processes-that-precede-anterograde-transport-in-axons
#14
Grayson DuRaine, Todd W Wisner, Paul Howard, David C Johnson
Herpes simplex virus (HSV) anterograde transport in neuronal axons is vital, allowing spread from latently-infected ganglia to epithelial tissues where viral progeny are produced in numbers allowing spread to other hosts. HSV membrane proteins gE/gI and US9 initiate the process of anterograde axonal transport ensuring that virus particles are transported from the cytoplasm into the most proximal segments of axons. These proteins do not appear to be important once HSV is inside axons. Previously we described HSV double mutants lacking both gE and US9 that failed to transport virus particles into axons...
March 22, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28289377/loss-of-saltation-and-presynaptic-action-potential-failure-in-demyelinated-axons
#15
Mustafa S Hamada, Marko A Popovic, Maarten H P Kole
In cortical pyramidal neurons the presynaptic terminals controlling transmitter release are located along unmyelinated axon collaterals, far from the original action potential (AP) initiation site, the axon initial segment (AIS). Once initiated, APs will need to reliably propagate over long distances and regions of geometrical inhomogeneity like branch points (BPs) to rapidly depolarize the presynaptic terminals and confer temporally precise synaptic transmission. While axon pathologies such as demyelinating diseases are well established to impede the fidelity of AP propagation along internodes, to which extent myelin loss affects propagation along BPs and axon collaterals is not well understood...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28284900/crosstalk-between-glia-extracellular-matrix-and-neurons
#16
REVIEW
Inseon Song, Alexander Dityatev
Extracellular matrix (ECM) molecules in the central nervous system form highly organized ECM structures around cell somata, axon initial segments, and synapses and play prominent roles in early development by guiding cell migration, neurite outgrowth and synaptogenesis, and by regulating closure of the critical period of development, synaptic plasticity and stability, cognitive flexibility, and axonal regeneration in adults. Major components of neural ECM, including chondroitin sulfate proteoglycans (CSPGs), tenascin-R and hyaluronic acid, are synthesized by both neurons and glial cells...
March 8, 2017: Brain Research Bulletin
https://www.readbyqxmd.com/read/28283581/mtcl1-plays-an-essential-role-in-maintaining-purkinje-neuron-axon-initial-segment
#17
Tomoko Satake, Kazunari Yamashita, Kenji Hayashi, Satoko Miyatake, Miwa Tamura-Nakano, Hiroshi Doi, Yasuhide Furuta, Go Shioi, Eriko Miura, Yukari H Takeo, Kunihiro Yoshida, Hiroyuki Yahikozawa, Naomichi Matsumoto, Michisuke Yuzaki, Atsushi Suzuki
The axon initial segment (AIS) is a specialized domain essential for neuronal function, the formation of which begins with localization of an ankyrin-G (AnkG) scaffold. However, the mechanism directing and maintaining AnkG localization is largely unknown. In this study, we demonstrate that in vivo knockdown of microtubule cross-linking factor 1 (MTCL1) in cerebellar Purkinje cells causes loss of axonal polarity coupled with AnkG mislocalization. MTCL1 lacking MT-stabilizing activity failed to restore these defects, and stable MT bundles spanning the AIS were disorganized in knockdown cells...
May 2, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28283543/kcnq-smit-complex-formation-facilitates-ion-channel-solute-transporter-cross-talk
#18
Daniel L Neverisky, Geoffrey W Abbott
Voltage-gated potassium channels formed by KCNQ2 and KCNQ3 are essential for normal neuronal excitability. KCNQ2/3 channel activity is augmented in vivo by phosphatidylinositol 4,5-bisphosphate (PIP2), which is generated from myo-inositol, an osmolyte transported into cells by sodium-dependent myo-inositol transporters (SMITs). Here, we discovered that KCNQ2/3 channels isoform-specifically colocalize with SMIT1 and SMIT2 at sciatic nerve nodes of Ranvier and in axon initial segments, and form channel-transporter complexes in vitro and in vivo KCNQ2/3 coexpression protected SMIT1 activity from the otherwise inhibitory effects of cellular depolarization imposed by elevating extracellular [K(+)], and KCNQ2 was required for potentiation of SMIT activity by myo-inositol preincubation...
March 10, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28269490/a-computational-model-of-orientation-dependent-activation-of-retinal-ganglion-cells
#19
Timothy Esler, Anthony N Burkitt, David B Grayden, Robert R Kerr, Bahman Tahayori, Hamish Meffin
Currently, a challenge in electrical stimulation for epiretinal prostheses is the avoidance of stimulation of axons of passage in the nerve fiber layer that originate from distant regions of the ganglion cell layer. A computational model of extracellular stimulation that captures the effect of neurite orientation in anisotropic tissue is developed using a modified version of the standard volume conductor model, known as the cellular composite model, embedded in a four layer model of the retina. Simulations are conducted to investigate the interaction of neural tissue orientation, electrode placement, and stimulation pulse duration and amplitude...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28235725/the-generator-site-in-acquired-autoimmune-neuromyotonia
#20
Miguel Oliveira Santos, Michael Swash, Mamede de Carvalho
OBJECTIVE: To investigate the origin of ectopic activity in neuromyotonia (NMT). METHODS: We studied two patients. In addition to routine studies, we tested synchronicity of spontaneous discharges in different motor units in simultaneous recordings made with two needle electrodes in the first dorsal interosseus muscle. Time-locked fasciculations in these double recordings would represent abnormal ectopic activity initiated in a nerve trunk with ephaptic stimulation of a nearby axon...
April 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
keyword
keyword
52538
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"