The pharmacological profile of the vesicular monoamine transporter resembles that of multidrug transporters

Yelin, Rodrigo; Schuldiner, Shimon

doi:10.1016/0014-5793(95)01346-6

Cited by 68 publications

(44 citation statements)

References 33 publications

(43 reference statements)

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“…It displays the pharmacological profile of a multidrug transporter (15) and provides resistance to MPP ϩ to CHO cells by removal into acidic compartments (10,20). Previous efforts demonstrated the feasibility of the yeast system when using a bacterial multidrug transporter (21) but failed to provide a fully functional expression of bVMAT2 and rVMAT1 (22).…”

Section: Discussionmentioning

confidence: 99%

“…Resistance Phenotype-The pharmacological profile of VMAT (15) and its ability to transport toxic compounds into acidic organelles enabled the development of a system of functional expression in S. cerevisiae cells. After screening of yeast strains that are potentially sensitive to toxic compounds and can then serve as suitable hosts for phenotypic expression of VMAT2, we chose the strain ADU1-7 for routine use (16).…”

Section: Functional Expression Of Rvmat2 In S Cerevisiae Confersmentioning

confidence: 99%

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Directed Evolution Reveals Hidden Properties of VMAT, a Neurotransmitter Transporter

Gros

Schuldiner

2010

Journal of Biological Chemistry

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The vesicular neurotransmitter transporter VMAT2 is responsible for the transport of monoamines into synaptic and storage vesicles. VMAT2 is the target of many psychoactive drugs and is essential for proper neurotransmission and survival. Here we describe a new expression system in Saccharomyces cerevisiae that takes advantage of the polyspecificity of VMAT2. Expression of rVMAT2 confers resistance to acriflavine and to the parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP ؉ ) by their removal into the yeast vacuole. This expression system allowed identification of a new substrate, acriflavine, and isolation of mutants with modified affinity to tetrabenazine (TBZ), a non-competitive inhibitor of VMAT2 that is used in the treatment of various movement disorders including Tourette syndrome and Huntington chorea. Whereas one type of mutant obtained displayed decreased affinity to TBZ, a second type showed only a slight decrease in the affinity to TBZ, displayed a higher K m to the neurotransmitter serotonin, but conferred increased resistance to acriflavine and MPP ؉ . A protein where both types of mutations were combined (with only three amino acid replacements) lost most of the properties of the neurotransmitter transporter (TBZ-insensitive, no transport of neurotransmitter) but displayed enhanced resistance to the above toxicants. The work described here shows that in the case of rVMAT2, loss of traits acquired in evolution of function (such as serotonin transport and TBZ binding) bring about an improvement in older functions such as resistance to toxic compounds. A process that has taken millions of years of evolution can be reversed by three mutations.Neurotransporters play central roles in the overall process of neurotransmission. Sodium-coupled plasma membrane transporters actively remove the neurotransmitters from the synaptic cleft in a step essential for termination of the signal. The release of neurotransmitter by exocytosis is possible because of their storage inside synaptic vesicles in a process that depends on vesicular H ϩ -coupled neurotransporters (VNT) 2 (1). Three families of proteins responsible for the uptake of transmitter by secretory vesicles have been identified, one that includes the vesicular monoamine transporters (VMATs) and acetylcholine transporters (VAChT), a second that includes the vesicular GABA transporter (VGAT), and a third that includes the vesicular glutamate transporters (VGLUTs) (2-4). Two monoamine transporters, VMAT1 and VMAT2, are responsible for the transport of dopamine, serotonin, adrenaline, and noradrenaline into the synaptic vesicles of neurons and the dense core vesicles of endocrine cells (2-4). VMAT2 is expressed by monoamine neurons in the central nervous system and selected peripheral endocrine populations. VMAT2 has a higher affinity for most monoamines than VMAT1, but only VMAT2 appears to recognize histamine (5, 6). Early studies using chromaffin granules from the adrenal medulla showed that the uptake of one protonated, and hence charged, cytoplasmic mo...

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Section: Discussionmentioning

confidence: 99%

Section: Functional Expression Of Rvmat2 In S Cerevisiae Confersmentioning

confidence: 99%

Directed Evolution Reveals Hidden Properties of VMAT, a Neurotransmitter Transporter

Gros

Schuldiner

2010

Journal of Biological Chemistry

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“…VMAT2 is a target of several agents, including reserpine, tetrabenazine, amphetamine, and methamphetamine (German et al, 1981;Fumagalli et al, 1999;Jones et al, 1999) as well as the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPPϩ) (Liu et al, 1992b). VMAT2 is a member of the toxin-extruding antiporter gene family, which includes some bacterial antibiotic resistance genes Yelin and Schuldiner, 1995). The function of VMAT2 is coupled to a proton ATPase in the vesicular membrane.…”

Section: Introductionmentioning

confidence: 99%

Reduced Vesicular Storage of Dopamine Causes Progressive Nigrostriatal Neurodegeneration

Caudle¹,

Richardson²,

Wang³

et al. 2007

J. Neurosci.

356

423

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The vesicular monoamine transporter 2 (VMAT2; SLC18A2) is responsible for packaging dopamine into vesicles for subsequent release and has been suggested to serve a neuroprotective role in the dopamine system. Here, we show that mice that express ϳ5% of normal VMAT2 (VMAT2 LO) display age-associated nigrostriatal dopamine dysfunction that ultimately results in neurodegeneration. Elevated cysteinyl adducts to L-DOPA and DOPAC are seen early and are followed by increased striatal protein carbonyl and 3-nitrotyrosine formation. These changes were associated with decreased striatal dopamine and decreased expression of the dopamine transporter and tyrosine hydroxylase. Furthermore, we observed an increase in ␣-synuclein immunoreactivity and accumulation and neurodegeneration in the substantia nigra pars compacta in aged VMAT2 LO mice. Thus, VMAT2 LO animals display nigrostriatal degeneration that begins in the terminal fields and progresses to eventual loss of the cell bodies, ␣-synuclein accumulation, and an L-DOPA responsive behavioral deficit, replicating many of the key aspects of Parkinson's disease. These data suggest that mishandling of dopamine via reduced VMAT2 expression is, in and of itself, sufficient to cause dopamine-mediated toxicity and neurodegeneration in the nigrostriatal dopamine system. In addition, the altered dopamine homeostasis resulting from reduced VMAT2 function may be conducive to pathogenic mechanisms induced by genetic or environmental factors thought to be involved in Parkinson's disease.

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“…In addition to the native substrates, VMATs interact with many clinically relevant drugs, including the psychostimulant 3,4-methylene-dioxymethamphetamine and the parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP + ) (7,13,14). For example, heterologous expression of VMATs protects mammalian and yeast cells against MPP + toxicity by sequestering the toxin in vesicles and away from its primary site of action in mitochondria (7,15).…”

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confidence: 99%

Emulating proton-induced conformational changes in the vesicular monoamine transporter VMAT2 by mutagenesis

Yaffe

Vergara-Jaque

Forrest

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Neurotransporters located in synaptic vesicles are essential for communication between nerve cells in a process mediated by neurotransmitters. Vesicular monoamine transporter (VMAT), a member of the largest superfamily of transporters, mediates transport of monoamines to synaptic vesicles and storage organelles in a process that involves exchange of two H + per substrate. VMAT transport is inhibited by the competitive inhibitor reserpine, a second-line agent to treat hypertension, and by the noncompetitive inhibitor tetrabenazine, presently in use for symptomatic treatment of hyperkinetic disorders. During the transport cycle, VMAT is expected to occupy at least three different conformations: cytoplasm-facing, occluded, and lumen-facing. The lumen-to cytoplasm-facing transition, facilitated by protonation of at least one of the essential membrane-embedded carboxyls, generates a binding site for reserpine. Here we have identified residues in the cytoplasmic gate and show that mutations that disrupt the interactions in this gate also shift the equilibrium toward the cytoplasm-facing conformation, emulating the effect of protonation. These experiments provide significant insight into the role of proton translocation in the conformational dynamics of a mammalian H + -coupled antiporter, and also identify key aspects of the mode of action and binding of two potent inhibitors of VMAT2: reserpine binds the cytoplasm-facing conformation, and tetrabenazine binds the lumen-facing conformation.neurotransmitter transporter | ion coupling | reserpine | tetrabenazine

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The pharmacological profile of the vesicular monoamine transporter resembles that of multidrug transporters

Cited by 68 publications

References 33 publications

Directed Evolution Reveals Hidden Properties of VMAT, a Neurotransmitter Transporter

Directed Evolution Reveals Hidden Properties of VMAT, a Neurotransmitter Transporter

Reduced Vesicular Storage of Dopamine Causes Progressive Nigrostriatal Neurodegeneration

Emulating proton-induced conformational changes in the vesicular monoamine transporter VMAT2 by mutagenesis

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