Functional expression of carnitine/organic cation transporter OCTN1 in mouse brain neurons: Possible involvement in neuronal differentiation

Nakamichi, Noritaka; Taguchi, Takayuki; Hosotani, Hiroshi; Wakayama, Tomohiko; Shimizu, Takuya; Sugiura, Tomoko; Iseki, Shoichi; Kato, Yukio

doi:10.1016/j.neuint.2012.08.004

Cited by 54 publications

(64 citation statements)

References 34 publications

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“…Thus, physiological roles of OCTN1 are assumed to be clearly different from those of OCTN2. It has been shown that OCTN1 is expressed in neurons, 52,53) but there is no report describing its function in astrocytes to date. However, in our unpublished observation, OCTN1 mRNA expression has been found in human primary astrocytes.…”

Section: Other Organic Cation Transportersmentioning

confidence: 99%

Functional Expression of Organic Ion Transporters in Astrocytes and Their Potential as a Drug Target in the Treatment of Central Nervous System Diseases

Furihata

Anzai

2017

Biological & Pharmaceutical Bulletin

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It has become widely acknowledged that astrocytes play essential roles in maintaining physiological central nervous system (CNS) activities. Astrocytes fulfill their roles partly through the manipulation of their plasma membrane transporter functions, and therefore these transporters have been regarded as promising drug targets for various CNS diseases. A representative example is excitatory amino acid transporter 2 (EAAT2), which works as a critical regulator of excitatory signal transduction through its glutamate uptake activity at the tripartite synapse. Thus, enhancement of EAAT2 functionality is expected to accelerate glutamate clearance at synapses, which is a promising approach for the prevention of over-excitation of glutamate receptors. In addition to such well-known astrocyte-specific transporters, cumulative evidence suggests that multi-specific organic ion transporters (i.e., organic cation/anion transporters [OCTs/OATs], carnitine/organic cation transporters [OCTNs], and organic anion transporting polypeptides [OATPs]) are also functionally expressed in astrocytes. Even though identification and characterization of their physiological/pathophysiological roles in astrocytes are in the initial stage, the findings obtained so far indicate that OCT3 and plasma membrane monoamine transporter are significantly involved in the clearance of biogenic amine neurotransmitters in the synaptic cleft, and that OCTN2 and OATP1C1 provide a cellular entry gate for carnitine/acetyl-L-carnitine and thyroxine, respectively. Therefore, organic ion transporters, including those mentioned above, are expected to become emerging pharmacological targets for various CNS diseases. With such expectations in mind, this review will briefly summarize the functional expression of organic ion transporters in astrocytes.

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Section: Other Organic Cation Transportersmentioning

confidence: 99%

Functional Expression of Organic Ion Transporters in Astrocytes and Their Potential as a Drug Target in the Treatment of Central Nervous System Diseases

Furihata

Anzai

2017

Biological & Pharmaceutical Bulletin

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“…Cell Cultures Primary cortical neuronal cultures were prepared according to the method of Nakamichi et al 21) In brief, cerebral cortices from 15-d-old embryonic ICR mice were dissected and incubated with 0.25% trypsin in phosphate-buffered saline (PBS) containing 0.5% glucose at 37°C for 20 min. Cells were mechanically dissociated in culture medium by using a 1000 µL pipette tip and plated at a density of 1.5×10 5 cells/cm 2 on plastic dishes coated with 7.5 µg/mL poly-L-lysine.…”

Section: Methodsmentioning

confidence: 99%

“…Under these culture conditions, more than 99% of cells were immunoreactive with antibody against microtubule-associated protein 2. 21) Mouse neuroblastoma-derived cell line Neuro2a cells were plated on at 1.0×10…”

Section: Methodsmentioning

confidence: 99%

“…21) In brief, cultured cells were washed once with PBS and incubated with MTT solution (0.5 mg/mL in PBS) for 1 h at 37°C. Subsequently, solubilizing solution (0.04 M HCl in isopropanol) at equivalent volume to the MTT solution was added, and the mixture was well shaken for 10 min to dissolve the formazan.…”

Section: -(45-dimethylthiazol-2-yl)-25-diphenyltetrazolium Bromidementioning

confidence: 99%

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Screening to Identify Multidrug Resistance-Associated Protein Inhibitors with Neuroblastoma-Selective Cytotoxicity

Nakamichi

Ishimoto

Yamauchi

et al. 2016

Biological & Pharmaceutical Bulletin

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The aim of the present study is to discover multidrug resistance-associated protein (MRP) inhibitors with neuroblastoma-selective cytotoxicity by means of fluorescence assay with a membrane-permeable fluorescent dye, Fluo-8 AM, based on our observation that gene expression of Mrp3 in neuroblastoma Neuro2a cells was remarkably higher than that in primary cultured cortical neurons, as determined by real-time PCR. Neuro2a cells showed minimal fluorescence upon incubation with Fluo-8 AM. However, blocking of Mrp3 efflux function by small interfering RNA (siRNA) transfection or inhibition with probenecid resulted in significant dye accumulation, observed as an increase of fluorescence. Interestingly, Mrp3 siRNA or probenecid treatment also resulted in increased cytotoxicity, as evidenced by decreased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-reducing activity of Neuro2a, with a concomitant increase in release of lactate dehydrogenase. On the other hand, primary cultured neurons exhibited higher fluorescence intensity after incubation with Fluo-8 AM regardless of addition of probenecid. Also, probenecid only minimally affected MTT-reducing activity. Thus, probenecid showed selective cytotoxicity towards Neuro2a cells. Based on these findings, we screened a series of established therapeutic agents for ability to induce Fluo-8 accumulation in Neuro2a cells. Several uricosuric and nonsteroidal anti-inflammatory drugs were identified, and these drugs were confirmed to decrease MTT-reducing activity selectively in Neuro2a. There was a negative linear correlation between Fluo-8 accumulation and cytotoxicity of these agents. Although the compounds identified here are insufficiently potent for practical application, further screening to discover higher-affinity MRP3 inhibitors using larger chemical libraries may uncover drug candidates with potent neuroblastoma-selective cytotoxicity.

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“…[61] Similarly, specific substrate transporters in the SLC1 (PM glutamate, 610 aspartate or other neurotransmitter carriers), in the SLC6 (PM neurotransmitter and amino acid transporters) and in the SLC17 family (vesicular glutamate transporters) are recognized as regulated marker proteins, especially in neuronal differentiation. [62] An isoform of the PM Na-H exchan-615 ger (SLC9) proteins, SLC9C1, is selectively expressed in spermatozoa; SLC11A2 (a metal transporter) and SLC19A2 (a thiamin transporter) are essential in erythroid progenitor cells, while SLC16A13 (a PM proton-linked monocarboxylate transporter) is almost exclusively localized in bone mar-620 row stem cells (see [63,64], and [52,65]). …”

mentioning

confidence: 99%

The importance of drug transporters in human pluripotent stem cells and in early tissue differentiation

Apáti

Szebényi

Erdei

et al. 2015

Expert Opinion on Drug Metabolism & Toxicology

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Functional expression of carnitine/organic cation transporter OCTN1 in mouse brain neurons: Possible involvement in neuronal differentiation

Cited by 54 publications

References 34 publications

Functional Expression of Organic Ion Transporters in Astrocytes and Their Potential as a Drug Target in the Treatment of Central Nervous System Diseases

Functional Expression of Organic Ion Transporters in Astrocytes and Their Potential as a Drug Target in the Treatment of Central Nervous System Diseases

Screening to Identify Multidrug Resistance-Associated Protein Inhibitors with Neuroblastoma-Selective Cytotoxicity

The importance of drug transporters in human pluripotent stem cells and in early tissue differentiation

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