scholarly journals Active presynaptic ribosomes in mammalian brain nerve terminals, and increased transmitter release after protein synthesis inhibition

2018 ◽  
Author(s):  
Matthew S. Scarnati ◽  
Rahul Kataria ◽  
Mohana Biswas ◽  
Kenneth G. Paradiso
Keyword(s):  
Protein Synthesis ◽  
Nerve Terminal ◽  
Brain Slices ◽  
Mammalian Brain ◽  
Nerve Terminals ◽  
Local Translation ◽  
Vesicle Recycling ◽  
Presynaptic Vesicle ◽  
Presynaptic Nerve Terminals ◽  
Presynaptic Protein

AbstractPresynaptic neuronal activity requires the localization of thousands of proteins that are typically synthesized in the soma and transported to nerve terminals. Local translation for some dendritic proteins occurs, but local translation in mammalian presynaptic nerve terminals is difficult to demonstrate. Here, we present evidence for local presynaptic protein synthesis in the mammalian brain at a glutamatergic nerve terminal. We show an essential ribosomal component, 5.8s rRNA, in terminals. We also show active translation in nerve terminals, in situ, in brain slices demonstrating ongoing presynaptic protein synthesis. After inhibiting translation for ~1 hour, the presynaptic terminal exhibits increased spontaneous release, and increased evoked release with an increase in vesicle recycling during stimulation trains. Postsynaptic response, shape and amplitude were not affected. We conclude that ongoing protein synthesis limits vesicle release at the nerve terminal which reduces the need for presynaptic vesicle replenishment, thus conserving energy required for maintaining synaptic transmission.

scholarly journals Active presynaptic ribosomes in the mammalian brain, and altered transmitter release after protein synthesis inhibition

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Matthew S Scarnati ◽  
Rahul Kataria ◽  
Mohana Biswas ◽  
Kenneth G Paradiso
Keyword(s):  
Protein Synthesis ◽  
Brain Slices ◽  
Decay Rates ◽  
Mammalian Brain ◽  
Nerve Terminals ◽  
Local Translation ◽  
Replenishment Rate ◽  
Pulse Ratio ◽  
Presynaptic Nerve Terminals ◽  
Presynaptic Protein

Presynaptic neuronal activity requires the localization of thousands of proteins that are typically synthesized in the soma and transported to nerve terminals. Local translation for some dendritic proteins occurs, but local translation in mammalian presynaptic nerve terminals is difficult to demonstrate. Here, we show an essential ribosomal component, 5.8S rRNA, at a glutamatergic nerve terminal in the mammalian brain. We also show active translation in nerve terminals, in situ, in brain slices demonstrating ongoing presynaptic protein synthesis in the mammalian brain. Shortly after inhibiting translation, the presynaptic terminal exhibits increased spontaneous release, an increased paired pulse ratio, an increased vesicle replenishment rate during stimulation trains, and a reduced initial probability of release. The rise and decay rates of postsynaptic responses were not affected. We conclude that ongoing protein synthesis can limit excessive vesicle release which reduces the vesicle replenishment rate, thus conserving the energy required for maintaining synaptic transmission.

scholarly journals The regulation of cytosolic pH in isolated presynaptic nerve terminals from rat brain.

1988 ◽  
Vol 91 (2) ◽  
pp. 289-303 ◽  
Author(s):  
D A Nachshen ◽  
P Drapeau
Keyword(s):  
Rat Brain ◽  
Parent Compound ◽  
Mammalian Brain ◽  
Fluorescence Signal ◽  
Nerve Terminals ◽  
Free Medium ◽  
Cytosolic Ph ◽  
Methyl Ester Derivative ◽  
Synaptosomal Membrane ◽  
Presynaptic Nerve Terminals

Cytosolic pH (pHi) was measured in presynaptic nerve terminals isolated from rat brain (synaptosomes) using a fluorescent pH indicator, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). The synaptosomes were loaded with BCECF by incubation with the membrane-permanent acetoxy-methyl ester derivative of BCECF, which is hydrolyzed by intracellular esterases to the parent compound. pHi was estimated by calibrating the fluorescence signal after permeabilizing the synaptosomal membrane by two different methods. Synaptosomes loaded with 15-90 microM BCECF were estimated to have a pHi of 6.94 +/- 0.02 (mean +/- standard error; n = 54) if the fluorescence signal was calibrated after permeabilizing with digitonin; a similar value was obtained using synaptosomes loaded with 10 times less BCECF (6.9 +/- 0.1; n = 5). When the fluorescence signal was calibrated by permeabilizing the synaptosomal membrane to H+ with gramicidin and nigericin, pHi was estimated to be 7.19 +/- 0.03 (n = 12). With the latter method, pHi = 6.95 +/- 0.09 (n = 14) when the synaptosomes were loaded with 10 times less BCECF. Thus, pHi in synaptosomes was approximately 7.0 and could be more precisely monitored using the digitonin calibration method at higher BCECF concentrations. When synaptosomes were incubated in medium containing 20 mM NH4Cl and then diluted into NH4Cl-free medium, pHi immediately acidified to a level of approximately 6.6. After the acidification, pHi recovered over a period of a few minutes. The buffering capacity of the synaptosomes was estimated to be approximately 50 mM/pH unit. Recovery was substantially slowed by incubation in an Na-free medium, by the addition of amiloride (KI = 3 microM), and by abolition of the Nao/Nai gradient. pHi and its recovery after acidification were not affected by incubation in an HCO3-containing medium; disulfonic stilbene anion transport inhibitors (SITS and DIDS, 1 mM) and replacement of Cl with methylsulfonate did not affect the rate of recovery of pHi. It appears that an Na+/H+ antiporter is the primary regulator of pHi in mammalian brain nerve terminals.

scholarly journals Neuron–glia interactions: the roles of Schwann cells in neuromuscular synapse formation and function

2011 ◽  
Vol 31 (5) ◽  
pp. 295-302 ◽  
Author(s):  
Yoshie Sugiura ◽  
Weichun Lin
Keyword(s):  
Schwann Cells ◽  
Motor Neurons ◽  
Nerve Terminal ◽  
Synapse Formation ◽  
Neuromuscular Synapse ◽  
Synaptic Activity ◽  
Nerve Terminals ◽  
Presynaptic Nerve Terminal ◽  
Presynaptic Nerve Terminals ◽  
And Function

The NMJ (neuromuscular junction) serves as the ultimate output of the motor neurons. The NMJ is composed of a presynaptic nerve terminal, a postsynaptic muscle and perisynaptic glial cells. Emerging evidence has also demonstrated an existence of perisynaptic fibroblast-like cells at the NMJ. In this review, we discuss the importance of Schwann cells, the glial component of the NMJ, in the formation and function of the NMJ. During development, Schwann cells are closely associated with presynaptic nerve terminals and are required for the maintenance of the developing NMJ. After the establishment of the NMJ, Schwann cells actively modulate synaptic activity. Schwann cells also play critical roles in regeneration of the NMJ after nerve injury. Thus, Schwann cells are indispensable for formation and function of the NMJ. Further examination of the interplay among Schwann cells, the nerve and the muscle will provide insights into a better understanding of mechanisms underlying neuromuscular synapse formation and function.

scholarly journals Collagen-derived matricryptins promote inhibitory nerve terminal formation in the developing neocortex

2016 ◽  
Vol 212 (6) ◽  
pp. 721-736 ◽  
Author(s):  
Jianmin Su ◽  
Jiang Chen ◽  
Kumiko Lippold ◽  
Aboozar Monavarfeshani ◽  
Gabriela Lizana Carrillo ◽  
...  
Keyword(s):  
Neuronal Activity ◽  
Nerve Terminal ◽  
Inhibitory Synapses ◽  
Mammalian Brain ◽  
Nerve Terminals ◽  
Brain Disorders ◽  
Integrin Receptors ◽  
Developing Neocortex ◽  
Cortical Circuit ◽  
Circuit Formation

Inhibitory synapses comprise only ∼20% of the total synapses in the mammalian brain but play essential roles in controlling neuronal activity. In fact, perturbing inhibitory synapses is associated with complex brain disorders, such as schizophrenia and epilepsy. Although many types of inhibitory synapses exist, these disorders have been strongly linked to defects in inhibitory synapses formed by Parvalbumin-expressing interneurons. Here, we discovered a novel role for an unconventional collagen—collagen XIX—in the formation of Parvalbumin+ inhibitory synapses. Loss of this collagen results not only in decreased inhibitory synapse number, but also in the acquisition of schizophrenia-related behaviors. Mechanistically, these studies reveal that a proteolytically released fragment of this collagen, termed a matricryptin, promotes the assembly of inhibitory nerve terminals through integrin receptors. Collectively, these studies not only identify roles for collagen-derived matricryptins in cortical circuit formation, but they also reveal a novel paracrine mechanism that regulates the assembly of these synapses.

Ion Channels in Presynaptic Nerve Terminals and Control of Transmitter Release

1999 ◽  
Vol 79 (3) ◽  
pp. 1019-1088 ◽  
Author(s):  
Alon Meir ◽  
Simona Ginsburg ◽  
Alexander Butkevich ◽  
Sylvia G. Kachalsky ◽  
Igor Kaiserman ◽  
...  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Nerve Terminal ◽  
Transmitter Release ◽  
Surface Membrane ◽  
Basic Function ◽  
Fine Tuning ◽  
Nerve Terminals ◽  
Presynaptic Nerve Terminal ◽  
Presynaptic Nerve Terminals

The primary function of the presynaptic nerve terminal is to release transmitter quanta and thus activate the postsynaptic target cell. In almost every step leading to the release of transmitter quanta, there is a substantial involvement of ion channels. In this review, the multitude of ion channels in the presynaptic terminal are surveyed. There are at least 12 different major categories of ion channels representing several tens of different ion channel types; the number of different ion channel molecules at presynaptic nerve terminals is many hundreds. We describe the different ion channel molecules at the surface membrane and inside the nerve terminal in the context of their possible role in the process of transmitter release. Frequently, a number of different ion channel molecules, with the same basic function, are present at the same nerve terminal. This is especially evident in the cases of calcium channels and potassium channels. This abundance of ion channels allows for a physiological and pharmacological fine tuning of the process of transmitter release and thus of synaptic transmission.

Single K+-channel current measurements from brain synaptosomes in lipid bilayers

1983 ◽  
Vol 245 (1) ◽  
pp. C151-C156 ◽  
Author(s):  
M. T. Nelson ◽  
M. Roudna ◽  
E. Bamberg
Keyword(s):  
Ion Channels ◽  
Lipid Bilayers ◽  
Single Channel ◽  
Mammalian Brain ◽  
K Channel ◽  
Kinetic Properties ◽  
Nerve Terminals ◽  
Planar Lipid Bilayers ◽  
Presynaptic Nerve Terminals ◽  
Single Channel Currents

Ion channels from a rat brain preparation enriched in presynaptic nerve terminals (synaptosomes) were incorporated into planar lipid bilayers. Experiments examined macroscopic (channel-ensemble) currents as well as single-channel currents. Four single-channel conductances (ranging from 10 to 40 pS) were usually observed, each with distinct kinetic properties. All the observed channels selected for K+ over Cl-. These K+ channels may contribute to the resting K+ conductance of brain nerve terminals. Furthermore, this report demonstrates that the properties of ion channels from mammalian brain can be studied in planar lipid bilayers and suggests that this system can be readily extended to many additional investigations on the electrical properties of brain membranes.

scholarly journals Clathrin-coated vesicles in nervous tissue are involved primarily in synaptic vesicle recycling.

1992 ◽  
Vol 118 (6) ◽  
pp. 1379-1388 ◽  
Author(s):  
P R Maycox ◽  
E Link ◽  
A Reetz ◽  
S A Morris ◽  
R Jahn
Keyword(s):  
Synaptic Vesicle ◽  
Nerve Terminal ◽  
Synaptic Vesicles ◽  
Nervous Tissue ◽  
Coated Vesicles ◽  
Nerve Terminals ◽  
Coat Proteins ◽  
Synaptic Vesicle Recycling ◽  
Vesicle Recycling ◽  
Vesicle Proteins

The recycling of synaptic vesicles in nerve terminals is thought to involve clathrin-coated vesicles. However, the properties of nerve terminal coated vesicles have not been characterized. Starting from a preparation of purified nerve terminals obtained from rat brain, we isolated clathrin-coated vesicles by a series of differential and density gradient centrifugation steps. The enrichment of coated vesicles during fractionation was monitored by EM. The final fraction consisted of greater than 90% of coated vesicles, with only negligible contamination by synaptic vesicles. Control experiments revealed that the contribution by coated vesicles derived from the axo-dendritic region or from nonneuronal cells is minimal. The membrane composition of nerve terminal-derived coated vesicles was very similar to that of synaptic vesicles, containing the membrane proteins synaptophysin, synaptotagmin, p29, synaptobrevin and the 116-kD subunit of the vacuolar proton pump, in similar stoichiometric ratios. The small GTP-binding protein rab3A was absent, probably reflecting its dissociation from synaptic vesicles during endocytosis. Immunogold EM revealed that virtually all coated vesicles carried synaptic vesicle proteins, demonstrating that the contribution by coated vesicles derived from other membrane traffic pathways is negligible. Coated vesicles isolated from the whole brain exhibited a similar composition, most of them carrying synaptic vesicle proteins. This indicates that in nervous tissue, coated vesicles function predominantly in the synaptic vesicle pathway. Nerve terminal-derived coated vesicles contained AP-2 adaptor complexes, which is in agreement with their plasmalemmal origin. Furthermore, the neuron-specific coat proteins AP 180 and auxilin, as well as the alpha a1 and alpha c1-adaptins, were enriched in this fraction, suggesting a function for these coat proteins in synaptic vesicle recycling.

Measurements of Vesicle Recycling in Central Neurons

Physiology ◽  
2001 ◽  
Vol 16 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Timothy A. Ryan ◽  
Harald Reuter
Keyword(s):  
Synaptic Transmission ◽  
Transmitter Release ◽  
Optical Methods ◽  
Nerve Terminals ◽  
Vesicle Recycling ◽  
Central Neurons ◽  
Presynaptic Nerve Terminals

Neurotransmitter-containing vesicles in presynaptic nerve terminals are essential for synaptic transmission. The vesicles undergo a cycle that leads to transmitter release by exocytosis followed by endocytosis and refilling of the vesicles. Here we discuss new optical methods that have helped researchers study this cycle at functional and molecular levels, which is essential for our understanding of the regulation of synaptic transmission.

scholarly journals Microtubules orchestrate local translation to enable cardiac growth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Emily A. Scarborough ◽  
Keita Uchida ◽  
Maria Vogel ◽  
Noa Erlitzki ◽  
Meghana Iyer ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Cell Periphery ◽  
Local Translation ◽  
Microtubule Network ◽  
Critical Determinant ◽  
Translation Rate ◽  
Cardiac Growth ◽  
Translational Machinery ◽  
Microtubule Motor ◽  
Discrete Domains

AbstractHypertension, exercise, and pregnancy are common triggers of cardiac remodeling, which occurs primarily through the hypertrophy of individual cardiomyocytes. During hypertrophy, stress-induced signal transduction increases cardiomyocyte transcription and translation, which promotes the addition of new contractile units through poorly understood mechanisms. The cardiomyocyte microtubule network is also implicated in hypertrophy, but via an unknown role. Here, we show that microtubules are indispensable for cardiac growth via spatiotemporal control of the translational machinery. We find that the microtubule motor Kinesin-1 distributes mRNAs and ribosomes along microtubule tracks to discrete domains within the cardiomyocyte. Upon hypertrophic stimulation, microtubules redistribute mRNAs and new protein synthesis to sites of growth at the cell periphery. If the microtubule network is disrupted, mRNAs and ribosomes collapse around the nucleus, which results in mislocalized protein synthesis, the rapid degradation of new proteins, and a failure of growth, despite normally increased translation rates. Together, these data indicate that mRNAs and ribosomes are actively transported to specific sites to facilitate local translation and assembly of contractile units, and suggest that properly localized translation – and not simply translation rate – is a critical determinant of cardiac hypertrophy. In this work, we find that microtubule based-transport is essential to couple augmented transcription and translation to productive cardiomyocyte growth during cardiac stress.

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