New Aspects of Neurotransmitter Release and Exocytosis: Dynamic and Differential Regulation of Synapsin I Phosphorylation by Acute Neuronal Excitation In Vivo

Abstract Rationale Cytochrome P450 2D (CYP2D) enzymes metabolize many addictive drugs, including methamphetamine. Variable CYP2D metabolism in the brain may alter CNS drug/metabolite concentrations, consequently affecting addiction liability and neuropsychiatric outcomes; components of these can be modeled by behavioral sensitization in rats. Methods To investigate the role of CYP2D in the brain in methamphetamine-induced behavioral sensitization, rats were pretreated centrally with a CYP2D irreversible inhibitor (or vehicle) 20 h prior to each of 7 daily methamphetamine (0.5 mg/kg subcutaneous) injections. In vivo brain microdialysis was used to assess brain drug and metabolite concentrations, and neurotransmitter release. Results CYP2D inhibitor (versus vehicle) pretreatment enhanced methamphetamine-induced stereotypy response sensitization. CYP2D inhibitor pretreatment increased brain methamphetamine concentrations and decreased the brain p-hydroxylation metabolic ratio. With microdialysis conducted on days 1 and 7, CYP2D inhibitor pretreatment exacerbated stereotypy sensitization and enhanced dopamine and serotonin release in the dorsal striatum. Day 1 brain methamphetamine and amphetamine concentrations correlated with dopamine and serotonin release, which in turn correlated with the stereotypy response slope across sessions (i.e., day 1 through day 7), used as a measure of sensitization. Conclusions CYP2D-mediated methamphetamine metabolism in the brain is sufficient to alter behavioral sensitization, brain drug concentrations, and striatal dopamine and serotonin release. Moreover, day 1 methamphetamine-induced neurotransmitter release may be an important predictor of subsequent behavioral sensitization. This suggests the novel contribution of CYP2D in the brain to methamphetamine-induced behavioral sensitization and suggests that the wide variation in human brain CYP2D6 may contribute to differential methamphetamine responses and chronic effects.

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Phosphorylation triggers presynaptic phase separation of Liprin-α3 to control active zone structure

10.1101/2020.10.28.357574 ◽

2020 ◽

Author(s):

Javier Emperador-Melero ◽

Man Yan Wong ◽

Shan Shan H. Wang ◽

Giovanni de Nola ◽

Tom Kirchhausen ◽

...

Keyword(s):

Phase Separation ◽

Active Zone ◽

Neurotransmitter Release ◽

Phosphorylation Site ◽

Double Knockout ◽

Zone Structure ◽

And Function ◽

Pkc Activation ◽

Liquid Liquid Phase Separation

AbstractLiquid-liquid phase separation enables the assembly of membrane-less subcellular compartments, but testing its biological functions has been difficult. The presynaptic active zone, protein machinery in nerve terminals that defines sites for neurotransmitter release, may be organized through phase separation. Here, we discover that the active zone protein Liprin-α3 rapidly and reversibly undergoes phase separation upon phosphorylation by PKC at a single site. RIM and Munc13 are co-recruited to membrane-attached condensates, and phospho-specific antibodies establish Liprin-α3 phosphorylation in vivo. At synapses of newly generated Liprin-α2/α3 double knockout mice, RIM, Munc13 and the pool of releasable vesicles were reduced. Re-expression of Liprin-α3 restored these defects, but mutating the Liprin-α3 phosphorylation site to abolish phase condensation prevented rescue. Finally, PKC activation acutely increased RIM, Munc13 and neurotransmitter release, which depended on the presence of phosphorylatable Liprin-α3. We conclude that Liprin-α3 phosphorylation rapidly triggers presynaptic phase separation to modulate active zone structure and function.

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Differential regulation of evoked and spontaneous neurotransmitter release by C-terminal modifications of complexin

Molecular and Cellular Neuroscience ◽

10.1016/j.mcn.2012.11.009 ◽

2013 ◽

Vol 52 ◽

pp. 161-172 ◽

Cited By ~ 28

Author(s):

Lauren K. Buhl ◽

Ramon A. Jorquera ◽

Yulia Akbergenova ◽

Sarah Huntwork-Rodriguez ◽

Dina Volfson ◽

...

Keyword(s):

Neurotransmitter Release ◽

Differential Regulation

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Neuronal excitation by angiotensin II in the rostral ventrolateral medulla of the rat in vitro

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.1.r272 ◽

1995 ◽

Vol 268 (1) ◽

pp. R272-R277 ◽

Cited By ~ 18

Author(s):

Y. W. Li ◽

P. G. Guyenet

Keyword(s):

Angiotensin Ii ◽

Excitatory Amino Acid ◽

Rostral Ventrolateral Medulla ◽

Ventrolateral Medulla ◽

Ang Ii ◽

Excitatory Amino Acid Receptor ◽

Neuronal Excitation ◽

Uk 14,304

We examined the effects of angiotensin II (ANG II) on spontaneous unit activity in slices of the rat rostral ventrolateral medulla (RVLM), ANG II (1-3 microM) excited 61% of a population of slowly and irregularly firing RVLM neurons (predrug, 1.2 +/- 0.1 spikes/s; postdrug, 4.6 +/- 0.3 spikes/s; n = 52). ANG II had no effect on pacemaker-like rapidly firing neurons (predrug, 8.6 +/- 0.4 spikes/s; n = 33). The effect of ANG II on slowly firing cells was repeatable and was reduced 75% by 3 microM losartan (baseline, 1.7 +/- 0.4 spikes/s; ANG II, 5.3 +/- 0.7 spikes/s; ANG II+losartan, 2.4 +/- 0.6 spikes/s; n = 12). The ongoing activity of slowly firing neurons was unaffected by 0.5-1 mM kynurenic acid (an ionotropic excitatory amino acid receptor antagonist). Most ANG II-responsive neurons (10 of 11) were inhibited by the alpha 2-adrenergic receptor agonist UK-14,304, but pacemaker-like neurons were not. In conclusion, the RVLM contains neurons excited by AT1 receptor agonists. These neurons are distinct from the previously described pacemaker nonadrenergic presympathetic cells. They may be responsible for the pressor effects produced by injecting ANG II into the RVLM in vivo.

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Differential Regulation of L-Arginine Metabolism through Arginase 1 during Infection with Leishmania mexicana Isolates Obtained from Patients with Localized and Diffuse Cutaneous Leishmaniasis

Infection and Immunity ◽

10.1128/iai.00963-19 ◽

2020 ◽

Vol 88 (7) ◽

Author(s):

Arturo A. Wilkins-Rodríguez ◽

Armando Pérez-Torres ◽

Alma R. Escalona-Montaño ◽

Laila Gutiérrez-Kobeh

Keyword(s):

Cutaneous Leishmaniasis ◽

Clinical Manifestations ◽

Differential Regulation ◽

Leishmania Mexicana ◽

Arginine Metabolism ◽

Content Type ◽

Arginase 1 ◽

Oxide Synthase ◽

Inducible Nitric Oxide

ABSTRACT l-Arginine metabolism through arginase 1 (Arg-1) and inducible nitric oxide synthase (NOS2) constitutes a fundamental axis for the resolution or progression of leishmaniasis. Infection with Leishmania mexicana can cause two distinct clinical manifestations: localized cutaneous leishmaniasis (LCL) and diffuse cutaneous leishmaniasis (DCL). In this work, we analyzed in an in vivo model the capacity of two L. mexicana isolates, one obtained from a patient with LCL and the other from a patient with DCL, to regulate the metabolism of l-arginine through Arg-1 and NOS2. Susceptible BALB/c mice were infected with L. mexicana isolates from both clinical manifestations, and the evolution of the infection as well as protein presence and activity of Arg-1 and NOS2 were evaluated. The lesions of mice infected with the DCL isolate were bigger, had higher parasite loads, and showed greater protein presence and enzymatic activity of Arg-1 than the lesions of mice infected with the LCL isolate. In contrast, NOS2 protein synthesis was poorly or not induced in the lesions of mice infected with the LCL or DCL isolate. The immunochemistry analysis of the lesions allowed the identification of highly parasitized macrophages positive for Arg-1, while no staining for NOS2 was found. In addition, we observed in lesions of patients with DCL macrophages with higher parasite loads and stronger Arg-1 staining than those in lesions of patients with LCL. Our results suggest that L. mexicana isolates obtained from patients with LCL or DCL exhibit different virulence or pathogenicity degrees and differentially regulate l-arginine metabolism through Arg-1.

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Regulation of SH3PX1 by dNedd4-long at the Drosophila neuromuscular junction

Journal of Biological Chemistry ◽

10.1074/jbc.ra118.005161 ◽

2018 ◽

Vol 294 (5) ◽

pp. 1739-1752 ◽

Cited By ~ 2

Author(s):

Samantha S. Wasserman ◽

Alina Shteiman-Kotler ◽

Kathryn Harris ◽

Konstantin G. Iliadi ◽

Avinash Persaud ◽

...

Keyword(s):

Neurotransmitter Release ◽

Neuromuscular Junctions ◽

Cell Periphery ◽

Middle Region ◽

Binding Partners ◽

Direct Binding ◽

Specific Regulation ◽

Neuromuscular Synaptogenesis

Drosophila Nedd4 (dNedd4) is a HECT E3 ubiquitin ligase present in two major isoforms: short (dNedd4S) and long (dNedd4Lo), with the latter containing two unique regions (N terminus and Middle). Although dNedd4S promotes neuromuscular synaptogenesis (NMS), dNedd4Lo inhibits it and impairs larval locomotion. To explain how dNedd4Lo inhibits NMS, MS analysis was performed to find its binding partners and identified SH3PX1, which binds dNedd4Lo unique Middle region. SH3PX1 contains SH3, PX, and BAR domains and is present at neuromuscular junctions, where it regulates active zone ultrastructure and presynaptic neurotransmitter release. Here, we demonstrate direct binding of SH3PX1 to the dNedd4Lo Middle region (which contains a Pro-rich sequence) in vitro and in cells, via the SH3PX1-SH3 domain. In Drosophila S2 cells, dNedd4Lo overexpression reduces SH3PX1 levels at the cell periphery. In vivo overexpression of dNedd4Lo post-synaptically, but not pre-synaptically, reduces SH3PX1 levels at the subsynaptic reticulum and impairs neurotransmitter release. Unexpectedly, larvae that overexpress dNedd4Lo post-synaptically and are heterozygous for a null mutation in SH3PX1 display increased neurotransmission compared with dNedd4Lo or SH3PX1 mutant larvae alone, suggesting a compensatory effect from the remaining SH3PX1 allele. These results suggest a post-synaptic–specific regulation of SH3PX1 by dNedd4Lo.

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