Inner Blood–Retinal Barrier Mediates L-Isomer-Predominant Transport of Serine

Tachikawa, Masanori; Okamoto, Masashi; Hirose, Shirou; Yoneyama, Daisuke; Akanuma, Shin Ichi; Hosoya, Ken

doi:10.1002/jps.22626

Cited by 11 publications

(4 citation statements)

References 49 publications

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“…The mock cells were seeded at a density of 1.0 × 10 5 cells/well on similar poly- d -lysine-coated 24-well plates because ABCA8/HEK293 cells grow more slowly than the mock cells. The cells were incubated for 48 h. The uptake assay was performed according to the methods previously reported . The culture medium was removed, and the cells were washed three times with the extracellular fluid (ECF) buffer (122 mM NaCl, 3 mM KCl, 0.4 mM K 2 HPO 4 , 25 mM NaHCO 3 , 1.2 mM MgSO 4 , 1.4 mM CaCl 2 , 10 mM d -glucose, 10 mM HEPES, pH 7.4).…”

Section: Methodsmentioning

confidence: 99%

“…The cells were incubated for 48 h. The uptake assay was performed according to the methods previously reported. 36 The culture medium was removed, and the cells were washed three times with the extracellular fluid (ECF) buffer (122 mM NaCl, 3 mM KCl, 0.4 mM K 2 HPO 4 , 25 mM NaHCO 3 , 1.2 mM MgSO 4 , 1.4 mM CaCl 2 , 10 mM D-glucose, 10 mM HEPES, pH 7.4). Then, the cells were incubated in ECF buffer containing [ 3 H]taurocholic acid (1.00 μM) (PerkinElmer), [ 17 on uptake and efflux activities in short-size ABCA8-expressing Xenopus laevis oocytes for several organic anions, presumably at an equilibrium state.…”

Section: Molecular Pharmaceuticsmentioning

confidence: 99%

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ATP-Binding Cassette Transporter A Subfamily 8 Is a Sinusoidal Efflux Transporter for Cholesterol and Taurocholate in Mouse and Human Liver

et al. 2018

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The ATP-binding cassette (ABC) transporter A subfamily 8 (ABCA8) belongs to the ABCA6-like transporters subgroup, which is distinct from the ABCA1-like subgroup in the ABCA family. The expression and function of the short-size human ABCA8 lacking one of the two ATP-binding domains for ATP hydrolysis, which are regularly present in the other ABCA transporters, have been reported. However, the functional differences between the short-size human ABCA8 and full-size human ABCA8, which has the two ATP-binding domains, remain unknown. The purpose of the present study was to clarify the tissue expression profiles of ABCA6-like and ABCA1-like subgroup transporters and the functional characteristics of ABCA8 in mouse and human. The tissue distribution of mouse ABCA (mABCA) transporter protein and the changes in mABCA8 protein expression levels in a mouse model of obstructive cholestasis were elucidated by means of quantitative targeted absolute proteomics (QTAP). The transport characteristics were clarified in a HEK293 cell line overexpressing full-size ABCA8 protein. QTAP and immunohistochemical analyses revealed that mABCA transporters exhibited the distinct protein expression patterns in the tissues, and mABCA8b, its mouse orthologue, was abundant in the liver and predominantly distributed in sinusoidal membranes of the hepatocytes. Further, protein expression of mABCA8b was decreased in the mouse cholestasis liver. Changes of mABCA8b expression level in cholestasis were similar to those of mABCA1, a sinusoidal cholesterol efflux transporter. Uptake and efflux assays showed that ABCA8 mediates efflux of [H]cholesterol and [H]taurocholate, while it showed no significant efflux activity for [H]estrone sulfate, [H]digoxin, [H]vinblastine, [H]para-aminohippuric acid, [H]oleic acid, [C]nicotine, or [H]methotrexate. [H]Cholesterol efflux was increased by extracellularly applied taurocholate. These results suggest that mABCA8b/ABCA8 functions as a sinusoidal efflux transporter for at least cholesterol and taurocholate in mouse and human liver.

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Section: Methodsmentioning

confidence: 99%

Section: Molecular Pharmaceuticsmentioning

confidence: 99%

ATP-Binding Cassette Transporter A Subfamily 8 Is a Sinusoidal Efflux Transporter for Cholesterol and Taurocholate in Mouse and Human Liver

et al. 2018

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“…As model cells of the rat BBB and inner BRB, TR-BBB and TR-iBRB2 cells were utilized [48,49]. These cells were cultured following the previous manuscript [51] and seeded onto collagen type I-coated 24-well plate (Corning, Kennebunk, ME, USA) at a density of 5 × 10 4 cells/cm 2 . The cells were cultured for 2 days and then washed with extracellular fluid buffer (122 mM NaCl, 25 mM NaHCO 3 , 3 mM KCl, 1.4 mM CaCl 2 , 1.2 mM MgSO 4 , 0.4 mM K 2 HPO 4 , 10 mM D-glucose, 10 mM 2-[4-(2-hydroxyethyl)-1piperazinyl]ethanesulfonic acid-NaOH, pH 7.4) at 37 • C. The extracellular fluid buffer containing [ 3 H]nicotine (85 Ci/mmol; American Radiolabeled Chemicals, St. Louis, MO, USA) or [ 3 H]verapamil (80 Ci/mmol; American Radiolabeled Chemicals) at a concentration of 0.5 µCi/mL in the absence or presence of test compounds at 200 µM with 1.0% DMSO was applied to the cells and incubated at 37 • C for designed time ([ 3 H]nicotine, 10 sec; [ 3 H]verapamil, 3 min).…”

Section: In Vitro Effect Of the Compound On The Transport Of Cationic...mentioning

confidence: 99%

Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A

Okada

Takashima

et al. 2021

Molecules

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The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama.

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“…[8][9][10] Our previous studies have shown that mRNAs of ASCT1, ASCT2, xCT, and 4F2hc are expressed in the in vitro model of rat inner BRB, TRiBRB2 cells. 11,12) In contrast, mRNA and/or protein expression of EAAT1-5 have not been identified yet. To understand the properties of L-Glu exchange between the circulating blood and retina, it is important to determine the contribution of these SLC families to L-Glu transport at the inner BRB.…”

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confidence: 99%

Excitatory Amino Acid Transporter 1-Mediated L-Glutamate Transport at the Inner Blood–Retinal Barrier: Possible Role in L-Glutamate Elimination from the Retina

Sakurai

Akanuma

Usui

et al. 2015

Biological & Pharmaceutical Bulletin

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The purpose of this study was to elucidate the transport mechanism(s) of L-glutamate (L-Glu), a neuroexcitatory neurotransmitter, in the inner blood-retinal barrier (BRB). The L-Glu transport was evaluated by an in vitro uptake study with a conditionally-immortalized rat retinal capillary endothelial cell line, TRiBRB2 cells. L-Glu uptake by TR-iBRB2 exhibited time-and concentration-dependence, and was composed of high-and low-affinity processes with Michaelis-Menten constants (K m ) of 19.3 µM and 275 µM, respectively. Under Na -free conditions, L-Glu uptake by TR-iBRB2 involved one-saturable kinetics with a K m of 190 µM, which is similar to that of the low-affinity process of L-Glu uptake under normal conditions. Moreover, substrates/inhibitors of system X c , which is involved in blood-to-retina transport of compounds across the inner BRB, strongly inhibited the L-Glu uptake under Na -free conditions, suggesting that Na -independent lowaffinity L-Glu transport at the inner BRB is carried out by system X c . Regarding the Na -dependent high affinity process of L-Glu transport at the inner BRB, L-Glu uptake by TR-iBRB2 under normal conditions was significantly inhibited by substrates/inhibitors of excitatory amino acid transporter (EAAT) 1-5, but not alanine-serine-cysteine transporters. Reverse-transcription polymerase chain reaction (RT-PCR) analysis and immunoblot analysis demonstrated that mRNA and protein of EAAT1 are expressed in TR-iBRB2 cells, whereas mRNAs and/or proteins of EAAT2-5 are not. Immunohistochemical analysis revealed that EAAT1 protein is localized on the abluminal membrane of the retinal capillaries. In conclusion, EAAT1 most likely mediates Na -dependent high-affinity L-Glu transport at the inner BRB and appears to take part in L-Glu elimination from the retina across the inner BRB.Key words excitatory amino acid transporter 1; inner blood-retinal barrier; L-glutamate L-Glutamate (L-Glu) is known as an excitatory neurotransmitter. In the retina, it has been reported that L-Glu controls the synaptic transmission between the photoreceptor and the bipolar/horizontal cells. 1) Excess L-Glu over-stimulates its receptors, such as N-methyl-D-aspartate receptors, and then causes neuronal cell death.2) In some case of glaucoma, it has been proposed that L-Glu-mediated neuro-excitotoxicity is involved in the progression of the disease.3) Hence, it is conceivable that some regulatory mechanisms of L-Glu concentration in the retina are present.The blood-retinal barrier (BRB) segregates the circulating blood from retinal interstitial fluid and regulates the exchange of compounds between the circulating blood and the retina. Regarding L-Glu transport across the BRB, Törnquist et al. have shown that in vivo blood-to-retina transport of [ 14 C]LGlu was not significantly inhibited, but increased 1.7-fold, by the co-administration of 10 mM unlabeled L-Glu.4) This result implies carrier-mediated efflux transport of L-Glu across the BRB. It has been shown that retinal capillary endothelial cells form the in...

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Inner Blood–Retinal Barrier Mediates L-Isomer-Predominant Transport of Serine

Cited by 11 publications

References 49 publications

ATP-Binding Cassette Transporter A Subfamily 8 Is a Sinusoidal Efflux Transporter for Cholesterol and Taurocholate in Mouse and Human Liver

ATP-Binding Cassette Transporter A Subfamily 8 Is a Sinusoidal Efflux Transporter for Cholesterol and Taurocholate in Mouse and Human Liver

Total Synthesis of Decahydroquinoline Poison Frog Alkaloids ent-cis-195A and cis-211A

Excitatory Amino Acid Transporter 1-Mediated L-Glutamate Transport at the Inner Blood–Retinal Barrier: Possible Role in L-Glutamate Elimination from the Retina

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