Localization of organic anion transporting polypeptide (Oatp) 1a4 and Oatp1c1 at the rat blood-retinal barrier

Akanuma, Shin Ichi; Hirose, Shiro; Tachikawa, Masanori; Hosoya, Ken

doi:10.1186/2045-8118-10-29

Cited by 33 publications

(28 citation statements)

References 18 publications

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“…luminal and abluminal [198], retinal pigmented epithelial cells, basolateral [198] rOATP2B1 retina [195] rOATP3A1 retina [195] rOATP4A1 retina [195,201] retina [201] human OCT1 retinal pigmented epithelium [202] OCT2 retina [194] 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 44 OCT3 retina [194] OCTN2 retina [194] rat rOCT1 retina [195]{ rOCT2 retina [195]{ mouse mOCT3 retinal pigmented epithelial cells [203] mOCTN1 blood retinal capillary epithelial cells [204] mOCTN2 blood retinal capillary epithelial cells [204] rat rOAT2 retina [195] rOAT3 retina [195], Blood retinal capillaries [205] primary cultured blood retinal capillary endothelial cells [205] blood retinal capillary endothelial cells: abluminal …”

Section: Drug Metabmentioning

confidence: 99%

Drug Transporters in the Central Nervous System

Stieger

Gao

2015

Clin Pharmacokinet

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Drug targets in the central nervous system (CNS) are numerous and important for drug therapy, e.g., of epilepsy or pain. Drugs and other xenobiotics as well as nutrients cannot freely cross the blood-brain barrier or freely enter cells across plasma membranes and therefore require transport systems. This overview summarizes the current knowledge on the expression of drug transporters in barriers shielding the CNS from the systemic circulation and as such controlling the pharmacokinetics of drugs in the CNS. The main drug transporter families covered are SLCO, SCL22A, ABCB, and ABCC, as genes of these families code for numerous drug transporters. While knowledge on messenger RNA expression in humans, rats, and mice is remarkable, there is clearly a gap in knowledge on the subcellular expression of transporters in specific cells in the CNS and in the barriers shielding the CNS from the systemic circulation. Recent methodologic developments including synthesis of drugs and endogenous substances for imaging will in the future allow the investigation of the function and physiologic role of transporters in the CNS including difficult-to-access systems such as the choroid plexus. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

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Section: Drug Metabmentioning

confidence: 99%

Drug Transporters in the Central Nervous System

Stieger

Gao

2015

Clin Pharmacokinet

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“…13) The details are included in Supplementary Materials. Immunohistochemical Study An immunohistochemical study was performed as described previously with minor modification, 17) and details are described in Supplementary Materials.…”

Section: Methodsmentioning

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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“…25,38 The crude membrane fractions (10 lg protein) of TR-iBRB2 cells or RPE-J cells were analyzed, where the anti-CAT1 polyclonal antibodies (0.2 lg/mL) and the horseradish peroxidase-conjugated antibodies (Merck Millipore) were used as primary and secondary antibodies, respectively.…”

Section: Western Blot Analysismentioning

confidence: 99%

“…25,38 The frozen sections (thickness 20 lm), prepared from Long-Evans rats, mounted on silanized glass slides were incubated with 10% goat serum (Nichirei, Tokyo, Japan) at room temperature. Guinea pig polyclonal anti-CAT1 antibodies (3.0 lg/mL) and rabbit polyclonal anti-GLUT1 antibodies (1.0 lg/mL) were used as the primary antibodies, 25 and Alexa Fluor 488-conjugated (Life Technologies, Carlsbad, CA, USA), Alexa Fluor 568-conjugated (Life Technologies), or Cy3-conjugated antibodies (Jackson Immuno Research, West Grove, PA, USA) were used as the secondary antibodies.…”

Section: Ruið%þor Buið%þmentioning

confidence: 99%

Impact of Cationic Amino Acid Transporter 1 on Blood-Retinal Barrier Transport of L-Ornithine

Kubo

Obata

Akanuma

et al. 2015

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To elucidate L-ornithine transport at the blood-retinal barrier (BRB).METHODS. Integration plot and retinal uptake index (RUI) were used to investigate the in vivo [ 3 H]L-ornithine transport across the BRB. In vitro transport studies of [ 3 H]L-ornithine were performed with TR-iBRB2 cells and RPE-J cells, the model cells of the inner and outer BRB, respectively. Immunohistochemistry was performed on cationic amino acid transporter 1 (CAT1/SLC7A1). RESULTS. The apparent influx permeability clearance of [3 H]L-ornithine was found to be 18. 7 lL/(minÁg retina), and the RUI of [ 3 H]L-ornithine was reduced by L-ornithine and L-arginine, suggesting the blood-to-retina transport of L-ornithine at the BRB. [3 H]L-Ornithine uptake by TR-iBRB2 cells showed a time-, temperature-and concentration-dependence with a MichaelisMenten constant (K m ) of 33.2 lM and a nonsaturable uptake rate (K d ) of 2.18 lL/(minÁmg protein). The uptake was Na þ -independent, and was inhibited by L-ornithine, L-arginine, and L-lysine, suggesting the involvement of CAT1 in L-ornithine transport at the inner BRB. Immunohistochemistry revealed the luminal and abluminal localization of CAT1 at the inner BRB, and at the basal localization at the outer BRB. Retinal pigment epithelium-J cells showed that the basal-to-cell (B-to-C) uptake of [ 3 H]L-ornithine was greater than that of the apical-tocell (A-to-C) uptake, and the B-to-C transport was inhibited by unlabeled L-ornithine, suggesting the involvement of CAT1 in the blood-to-cell transport of L-ornithine across the basal membrane at the outer BRB.CONCLUSIONS. These suggest the involvement of CAT1 in L-ornithine transport at the luminal and abluminal sides of the inner BRB and the basal side of the outer BRB.

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Localization of organic anion transporting polypeptide (Oatp) 1a4 and Oatp1c1 at the rat blood-retinal barrier

Cited by 33 publications

References 18 publications

Drug Transporters in the Central Nervous System

Drug Transporters in the Central Nervous System

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

Impact of Cationic Amino Acid Transporter 1 on Blood-Retinal Barrier Transport of L-Ornithine

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