13 results on '"Santos, Magda S."'
Search Results
2. Structural requirements for steady-state localization of the vesicular acetylcholine transporter
- Author
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Ferreira, Lucimar T., Santos, Magda S., Kolmakova, Natalia G., Koenen, Janaina, Barbosa, Jose, Jr, Gomez, Marcus V., Guatimosim, Cristina, Zhang, Xiaodong, Parsons, Stanley M., Prado, Vania F., and Prado, Marco A. M.
- Published
- 2005
3. Trafficking of the vesicular acetylcholine transporter in SN56 cells: a dynamin-sensitive step and interaction with the AP-2 adaptor complex
- Author
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Barbosa, José, Jr, Ferreira, Lucimar T., Martins-Silva, C., Santos, Magda S., Torres, Gonzalo E., Caron, Marc G., Gomez, Marcus V., Ferguson, Stephen S. G., Prado, Marco A. M., and Prado, Vania F.
- Published
- 2002
4. Visualization and Trafficking of the Vesicular Acetylcholine Transporter in Living Cholinergic Cells
- Author
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Santos, Magda S., Barbosa, José, Jr., Kushmerick, Christopher, Gomez, Marcus V., Prado, Vania F., and Prado, Marco A. M.
- Published
- 2000
5. Overcoming presynaptic effects of VAMP2 mutations with 4‐aminopyridine treatment.
- Author
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Simmons, Roxanne L., Li, Haiyan, Alten, Baris, Santos, Magda S., Jiang, Ruiji, Paul, Brianna, Lalani, Sanam J., Cortesi, Audrey, Parks, Kendall, Khandelwal, Nitin, Smith‐Packard, Bethany, Phoong, Malay A., Chez, Michael, Fisher, Heather, Scheuerle, Angela E., Shinawi, Marwan, Hussain, Shaun A., Kavalali, Ege T., Sherr, Elliott H., and Voglmaier, Susan M.
- Abstract
Clinical and genetic features of five unrelated patients with de novo pathogenic variants in the synaptic vesicle‐associated membrane protein 2 (VAMP2) reveal common features of global developmental delay, autistic tendencies, behavioral disturbances, and a higher propensity to develop epilepsy. For one patient, a cognitively impaired adolescent with a de novo stop‐gain VAMP2 mutation, we tested a potential treatment strategy, enhancing neurotransmission by prolonging action potentials with the aminopyridine family of potassium channel blockers, 4‐aminopyridine and 3,4‐diaminopyridine, in vitro and in vivo. Synaptic vesicle recycling and neurotransmission were assayed in neurons expressing three VAMP2 variants by live‐cell imaging and electrophysiology. In cellular models, two variants decrease both the rate of exocytosis and the number of synaptic vesicles released from the recycling pool, compared with wild‐type. Aminopyridine treatment increases the rate and extent of exocytosis and total synaptic charge transfer and desynchronizes GABA release. The clinical response of the patient to 2 years of off‐label aminopyridine treatment includes improved emotional and behavioral regulation by parental report, and objective improvement in standardized cognitive measures. Aminopyridine treatment may extend to patients with pathogenic variants in VAMP2 and other genes influencing presynaptic function or GABAergic tone, and tested in vitro before treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. VGLUT2 Trafficking Is Differentially Regulated by Adaptor Proteins AP-1 and AP-3.
- Author
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Haiyan Li, Santos, Magda S., Park, Chihyung K., Dobry, Yuriy, and Voglmaier, Susan M.
- Subjects
SYNAPTIC vesicles ,NEUROTRANSMITTERS ,EXCITATORY amino acid agents ,MEMBRANE proteins ,CELL membranes ,COATED vesicles - Abstract
Release of the major excitatory neurotransmitter glutamate by synaptic vesicle exocytosis depends on glutamate loading into synaptic vesicles by vesicular glutamate transporters (VGLUTs). The two principal isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in adult brain that broadly distinguishes cortical (VGLUT1) and subcortical (VGLUT2) systems, and correlates with distinct physiological properties in synapses expressing these isoforms. Differential trafficking of VGLUT1 and 2 has been suggested to underlie their functional diversity. Increasing evidence suggests individual synaptic vesicle proteins use specific sorting signals to engage specialized biochemical mechanisms to regulate their recycling. We observed that VGLUT2 recycles differently in response to high frequency stimulation than VGLUT1. Here we further explore the trafficking of VGLUT2 using a pHluorin-based reporter, VGLUT2-pH. VGLUT2-pH exhibits slower rates of both exocytosis and endocytosis than VGLUT1-pH. VGLUT2-pH recycling is slower than VGLUT1-pH in both hippocampal neurons, which endogenously express mostly VGLUT1, and thalamic neurons, which endogenously express mostly VGLUT2, indicating that protein identity, not synaptic vesicle membrane or neuronal cell type, controls sorting. We characterize sorting signals in the C-terminal dileucine-like motif, which plays a crucial role in VGLUT2 trafficking. Disruption of this motif abolishes synaptic targeting of VGLUT2 and essentially eliminates endocytosis of the transporter. Mutational and biochemical analysis demonstrates that clathrin adaptor proteins (APs) interact with VGLUT2 at the dileucine-like motif. VGLUT2 interacts with AP-2, a well-studied adaptor protein for clathrin mediated endocytosis. In addition, VGLUT2 also interacts with the alternate adaptors, AP-1 and AP-3. VGLUT2 relies on distinct recycling mechanisms from VGLUT1. Abrogation of these differences by pharmacological and molecular inhibition reveals that these mechanisms are dependent on the adaptor proteins AP-1 and AP-3. Further, shRNA-mediated knockdown reveals differential roles for AP-1 and AP-3 in VGLUT2 recycling. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
7. Protein Interactions of the Vesicular Glutamate Transporter VGLUT1.
- Author
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Santos, Magda S., Foss, Sarah M., Park, C. Kevin, and Voglmaier, Susan M.
- Subjects
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PROTEIN-protein interactions , *GLUTAMATE transporters , *NEUROTRANSMITTERS , *PROTEIN expression , *POLYPROLINE - Abstract
Exocytotic release of glutamate depends upon loading of the neurotransmitter into synaptic vesicles by vesicular glutamate transporters, VGLUTs. The major isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in synapses of the adult rodent brain that correlates with the probability of release and potential for plasticity. Indeed, expression of different VGLUT protein isoforms confers different properties of release probability. Expression of VGLUT1 or 2 protein also determines the kinetics of synaptic vesicle recycling. To identify molecular determinants that may be related to reported differences in VGLUT trafficking and glutamate release properties, we investigated some of the intrinsic differences between the two isoforms. VGLUT1 and 2 exhibit a high degree of sequence homology, but differ in their N- and C-termini. While the C-termini of VGLUT1 and 2 share a dileucine-like trafficking motif and a proline-, glutamate-, serine-, and threonine-rich PEST domain, only VGLUT1 contains two polyproline domains and a phosphorylation consensus sequence in a region of acidic amino acids. The interaction of a VGLUT1 polyproline domain with the endocytic protein endophilin recruits VGLUT1 to a fast recycling pathway. To identify trans-acting cellular proteins that interact with the distinct motifs found in the C-terminus of VGLUT1, we performed a series of in vitro biochemical screening assays using the region encompassing the polyproline motifs, phosphorylation consensus sites, and PEST domain. We identify interactors that belong to several classes of proteins that modulate cellular function, including actin cytoskeletal adaptors, ubiquitin ligases, and tyrosine kinases. The nature of these interactions suggests novel avenues to investigate the modulation of synaptic vesicle protein recycling. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
8. Sorting of the Vesicular GABA Transporter to Functional Vesicle Pools by an Atypical Dileucine-like Motif.
- Author
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Santos, Magda S., Park, C. Kevin, Foss, Sarah M., Haiyan Li, and Voglmaier, Susan M.
- Subjects
- *
SORTING devices , *GABA transporters , *VESICLE associated membrane protein , *SYNAPTIC vesicles , *PHYSIOLOGICAL effects of leucine , *CELLULAR signal transduction , *AMINO acids , *GENETIC mutation - Abstract
Increasing evidence indicates that individual synaptic vesicle proteins may use different signals, endocytic adaptors, and trafficking pathways for sorting to distinct pools of synaptic vesicles. Here, we report the identification of a unique amino acid motif in the vesicular GABA transporter (VGAT) that controls its synaptic localization and activity-dependent recycling. Mutational analysis of this atypical dileucine-like motif in rat VGAT indicates that the transporter recycles by interacting with the clathrin adaptor protein AP-2. However, mutation of a single acidic residue upstream of the dileucine-like motif leads to a shift to an AP-3-dependent trafficking pathway that preferentially targets the transporter to the readily releasable and recycling pool of vesicles. Real-time imaging with a VGAT-pHluorin fusion provides a useful approach to explore how unique sorting sequences target individual proteins to synaptic vesicles with distinct functional properties. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
9. Multiple Dileucine-like Motifs Direct VGLUT 1 Trafficking.
- Author
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Foss, Sarah M., Haiyan Li, Santos, Magda S., Edwards, Robert H., and Voglmaier, Susan M.
- Subjects
PHYSIOLOGICAL effects of leucine ,VESICLE associated membrane protein ,GLUTAMATE transporters ,ORGAN trafficking ,SYNAPTIC vesicles ,CELLULAR signal transduction ,NEURAL stimulation - Abstract
The vesicular glutamate transporters (VGLUTs) package glutamate into synaptic vesicles, and the two principal isoforms VGLUT 1 and VGLUT2 have been suggested to influence the properties of release. To understand how a VGLUT isoform might influence transmitter release, we have studied their trafficking and previously identified a dileucine-like endocytic motif in the C terminus of VGLUT1. Disruption of this motif impairs the activity-dependent recycling of VGLUT 1, but does not eliminate its endocytosis. We now report the identification of two additional dileucine-like motifs in the ? terminus of VGLUT 1 that are not well conserved in the other isoforms. In the absence of all three motifs, rat VGLUT1 shows limited accumulation at synaptic sites and no longer responds to stimulation. In addition, shRNA-mediated knockdown of clathrin adaptor proteins AP-1 and AP-2 shows that the C-terminal motif acts largely via AP-2, whereas the N-terminal motifs use AP-1. Without the C-terminal motif, knockdown of AP-1 reduces the proportion of VGLUT 1 that responds to stimulation. VGLUT1 thus contains multiple sorting signals that engage distinct trafficking mechanisms. In contrast to VGLUT1, the trafficking of VGLUT2 depends almost entirely on the conserved C-terminal dileucine-like motif: without this motif, a substantial fraction of VGLUT2 redistributes to the plasma membrane and the transporter's synaptic localization is disrupted. Consistent with these differences in trafficking signals, wild-type VGLUT 1 and VGLUT2 differ in their response to stimulation. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
10. Novel Strains of Mice Deficient for the Vesicular Acetylcholine Transporter: Insights on Transcriptional Regulation and Control of Locomotor Behavior.
- Author
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Martins-Silva, Cristina, De Jaeger, Xavier, Guzman, Monica S., Lima, Ricardo D. F., Santos, Magda S., Kushmerick, Christopher, Gomez, Marcus V., Caron, Marc G., Prado, Marco A. M., and Prado, Vania F.
- Subjects
ACETYLCHOLINE ,MICE ,CHOLINERGIC mechanisms ,NEURONS ,PHENOTYPES ,LOCOMOTION - Abstract
Defining the contribution of acetylcholine to specific behaviors has been challenging, mainly because of the difficulty in generating suitable animal models of cholinergic dysfunction. We have recently shown that, by targeting the vesicular acetylcholine transporter (VAChT) gene, it is possible to generate genetically modified mice with cholinergic deficiency. Here we describe novel VAChT mutant lines. VAChT gene is embedded within the first intron of the choline acetyltransferase (ChAT) gene, which provides a unique arrangement and regulation for these two genes. We generated a VAChT allele that is flanked by loxP sequences and carries the resistance cassette placed in a ChAT intronic region (FloxNeo allele). We show that mice with the FloxNeo allele exhibit differential VAChT expression in distinct neuronal populations. These mice show relatively intact VAChT expression in somatomotor cholinergic neurons, but pronounced decrease in other cholinergic neurons in the brain. VAChT mutant mice present preserved neuromuscular function, but altered brain cholinergic function and are hyperactive. Genetic removal of the resistance cassette rescues VAChT expression and the hyperactivity phenotype. These results suggest that release of ACh in the brain is normally required to ''turn down'' neuronal circuits controlling locomotion. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
11. VGLUT2 Trafficking Is Differentially Regulated by Adaptor Proteins AP-1 and AP-3.
- Author
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Li H, Santos MS, Park CK, Dobry Y, and Voglmaier SM
- Abstract
Release of the major excitatory neurotransmitter glutamate by synaptic vesicle exocytosis depends on glutamate loading into synaptic vesicles by vesicular glutamate transporters (VGLUTs). The two principal isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in adult brain that broadly distinguishes cortical (VGLUT1) and subcortical (VGLUT2) systems, and correlates with distinct physiological properties in synapses expressing these isoforms. Differential trafficking of VGLUT1 and 2 has been suggested to underlie their functional diversity. Increasing evidence suggests individual synaptic vesicle proteins use specific sorting signals to engage specialized biochemical mechanisms to regulate their recycling. We observed that VGLUT2 recycles differently in response to high frequency stimulation than VGLUT1. Here we further explore the trafficking of VGLUT2 using a pHluorin-based reporter, VGLUT2-pH. VGLUT2-pH exhibits slower rates of both exocytosis and endocytosis than VGLUT1-pH. VGLUT2-pH recycling is slower than VGLUT1-pH in both hippocampal neurons, which endogenously express mostly VGLUT1, and thalamic neurons, which endogenously express mostly VGLUT2, indicating that protein identity, not synaptic vesicle membrane or neuronal cell type, controls sorting. We characterize sorting signals in the C-terminal dileucine-like motif, which plays a crucial role in VGLUT2 trafficking. Disruption of this motif abolishes synaptic targeting of VGLUT2 and essentially eliminates endocytosis of the transporter. Mutational and biochemical analysis demonstrates that clathrin adaptor proteins (APs) interact with VGLUT2 at the dileucine-like motif. VGLUT2 interacts with AP-2, a well-studied adaptor protein for clathrin mediated endocytosis. In addition, VGLUT2 also interacts with the alternate adaptors, AP-1 and AP-3. VGLUT2 relies on distinct recycling mechanisms from VGLUT1. Abrogation of these differences by pharmacological and molecular inhibition reveals that these mechanisms are dependent on the adaptor proteins AP-1 and AP-3. Further, shRNA-mediated knockdown reveals differential roles for AP-1 and AP-3 in VGLUT2 recycling.
- Published
- 2017
- Full Text
- View/download PDF
12. Multiple dileucine-like motifs direct VGLUT1 trafficking.
- Author
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Foss SM, Li H, Santos MS, Edwards RH, and Voglmaier SM
- Subjects
- Adaptor Protein Complex 2 metabolism, Amino Acid Motifs physiology, Amino Acid Sequence, Animals, Cells, Cultured, Clathrin metabolism, Endocytosis physiology, Hippocampus cytology, Hippocampus metabolism, Hydrogen-Ion Concentration, Immunohistochemistry, Molecular Sequence Data, Mutant Chimeric Proteins genetics, Mutant Chimeric Proteins physiology, Polymerase Chain Reaction, RNA Interference, Rats, Vesicular Glutamate Transport Protein 1 genetics, Vesicular Glutamate Transport Protein 2 genetics, Vesicular Glutamate Transport Protein 2 physiology, Leucine genetics, Leucine physiology, Vesicular Glutamate Transport Protein 1 physiology
- Abstract
The vesicular glutamate transporters (VGLUTs) package glutamate into synaptic vesicles, and the two principal isoforms VGLUT1 and VGLUT2 have been suggested to influence the properties of release. To understand how a VGLUT isoform might influence transmitter release, we have studied their trafficking and previously identified a dileucine-like endocytic motif in the C terminus of VGLUT1. Disruption of this motif impairs the activity-dependent recycling of VGLUT1, but does not eliminate its endocytosis. We now report the identification of two additional dileucine-like motifs in the N terminus of VGLUT1 that are not well conserved in the other isoforms. In the absence of all three motifs, rat VGLUT1 shows limited accumulation at synaptic sites and no longer responds to stimulation. In addition, shRNA-mediated knockdown of clathrin adaptor proteins AP-1 and AP-2 shows that the C-terminal motif acts largely via AP-2, whereas the N-terminal motifs use AP-1. Without the C-terminal motif, knockdown of AP-1 reduces the proportion of VGLUT1 that responds to stimulation. VGLUT1 thus contains multiple sorting signals that engage distinct trafficking mechanisms. In contrast to VGLUT1, the trafficking of VGLUT2 depends almost entirely on the conserved C-terminal dileucine-like motif: without this motif, a substantial fraction of VGLUT2 redistributes to the plasma membrane and the transporter's synaptic localization is disrupted. Consistent with these differences in trafficking signals, wild-type VGLUT1 and VGLUT2 differ in their response to stimulation.
- Published
- 2013
- Full Text
- View/download PDF
13. Thyronamines inhibit plasma membrane and vesicular monoamine transport.
- Author
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Snead AN, Santos MS, Seal RP, Miyakawa M, Edwards RH, and Scanlan TS
- Subjects
- Animals, Cell Line, Cell Membrane physiology, Dose-Response Relationship, Drug, Humans, Protein Transport physiology, Rats, Rats, Sprague-Dawley, Cell Membrane metabolism, Thyronines chemistry, Thyronines physiology, Vesicular Monoamine Transport Proteins antagonists & inhibitors, Vesicular Monoamine Transport Proteins metabolism
- Abstract
Thyroid hormone has long been known to have important transcriptional regulatory activities. Recently, however, the presence of endogenous derivatives of thyroid hormone, thyronamines, has been reported in various mammalian tissues. These derivatives have potent in vitro activity with a class of orphan G-protein-coupled receptors, the trace amine-associated receptors, and profound in vivo effects when administered to mice. We report here a novel neuromodulatory role for thyronamines. In synaptosomal preparations and heterologous expression systems, thyronamines act as specific dopamine and norepinephrine reuptake inhibitors. Thyronamines also inhibit the transport of monoamines into synaptic vesicles. These observations expand the nontranscriptional role of thyroid hormone derivatives and may help to explain the pharmacological effects of thyronamines in vivo.
- Published
- 2007
- Full Text
- View/download PDF
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