Cationic amino acid transporter 1‐mediated <scp>l</scp>‐arginine transport at the inner blood–retinal barrier

Tomi, Masatoshi; Kitade, Naohisa; Hirose, Shirou; Yokota, Noriko; Akanuma, Shin Ichi; Tachikawa, Masanori; Hosoya, Ken

doi:10.1111/j.1471-4159.2009.06367.x

Cited by 43 publications

(43 citation statements)

References 38 publications

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“…1,15) TRrPCT1 cells and TR-iBRB2 cells were homogenized by the nitrogen cavitation technique (800 psi, 30 min, 4°C) in Trissucrose buffer (10 mM Tris-HCl, 250 mM sucrose, and 1 mM ethyleneglycol bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA); pH 7.4) containing a protease inhibitor cocktail (Sigma). The homogenized samples were centrifuged for 15 min at 10000×g and 4°C and the supernatants were centrifuged for 60 min at 100000×g and 4°C, and a crude membrane fraction was obtained from the pellets.…”

Section: Methodsmentioning

confidence: 99%

“…The membrane was then treated with blocking solution (20 mM Tris-HCl, 137 mM NaCl, 0.1% Tween-20, and 5% non-fat dry milk, pH 7.4) for 9 h at 4°C and incubated with guinea pig polyclonal anti-CAT1 antibody (0.2 µg/mL) for 12 h at 4°C. 15) The membrane was rinsed with washing solution (20 mM Tris-HCl, 137 mM NaCl, 0.1% Tween-20, and 0.1% non-fat dry milk, pH 7.4), and incubated with horseradish peroxidase-conjugated anti-guinea pig immunoglobulin G (IgG). The bands were visualized using an enhanced chemiluminescence kit (ECL plus; GE Healthcare).…”

Section: Methodsmentioning

confidence: 99%

“…4B). Using immunoblot analysis with the crude membrane fraction prepared from TR-rPCT1 cells and TR-iBRB2 cells, a positive control for the expression of CAT1, 15) the CAT1 antibody recognized a single protein band at ca. 90 kDa.…”

Section: Characteristics Of L-arg Uptake By Tr-rpct1 Cellsmentioning

confidence: 99%

“…13,14) AT/Slc7a9) transport both cationic and neutral amino acids, and represent an Na + -dependent and an Na + -independent transport system, respectively. 12) Our previous studies have revealed that L-Arg is transported from the circulating blood to the retina 15) and is taken up into Müller cells, which are glial cells in the retina, 16) via cationic amino acid transporters (CAT). Therefore, it is hypothesized that these transport systems take part in the transport of L-Arg in retinal pericytes.…”

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confidence: 99%

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Involvement of Cationic Amino Acid Transporter 1 in L-Arginine Transport in Rat Retinal Pericytes

Zakoji

Akanuma

Tachikawa

et al. 2015

Biological & Pharmaceutical Bulletin

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Nitric oxide (NO), a known relaxant, is produced in cells from L-arginine (L-Arg). Because the relaxation of retinal pericytes alters the microcirculatory hemodynamics, it is important to understand the manner of NO production in retinal pericytes. The purpose of this study was to clarify the molecular mechanism(s) of uptake of L-Arg in retinal pericytes using a conditionally immortalized rat retinal pericyte cell line (TR-rPCT1 cells) which expresses the mRNAs of endothelial NO synthase and inducible NO synthase. L-Arg uptake by TR-rPCT1 cells exhibited Na -independence and concentration-dependence with a K m of 28.9 µM. This process was strongly inhibited by substrates of cationic amino acid transporters (CAT), such as L-ornithine and L-lysine. In contrast, L-valine, L-leucine, and L-glutamine, which are substrates of cation/ neutral amino acid transport systems, such as system y L, system B 0, , and system b 0, , did not strongly inhibit L-Arg uptake by TR-rPCT1 cells. In addition, the expression of mRNA and protein of CAT1 in TRrPCT1 cells was observed by reverse transcription-polymerase chain reaction and immunoblot analyses. Taking these results into consideration, it appears that CAT1 is involved in L-Arg uptake by retinal pericytes and this is expected to play an important role in the relaxation of retinal pericytes, thereby modulating the microcirculatory hemodynamics in the retina.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Characteristics Of L-arg Uptake By Tr-rpct1 Cellsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Involvement of Cationic Amino Acid Transporter 1 in L-Arginine Transport in Rat Retinal Pericytes

Zakoji

Akanuma

Tachikawa

et al. 2015

Biological & Pharmaceutical Bulletin

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“…As typical examples, studies of the inner BRB have suggested the role of transporters, such as glucose transporter (GLUT1/solute carrier 2A1 (SLC2A1)), Ltype amino acid transporter (LAT1/SLC7A5), cationic amino acid transporter 1 (CAT1/SLC7A1), Na + -dependent multivitamin transporter (SMVT/SLC5A6), equilibrative nucleoside transporter 2 (ENT2/SLC29A2) and taurine transporter (TauT/ SLC6A6), in supplying nutrients into the retina. [4][5][6][7][8][9][10] Other studies have shown the expression of ATP-biding cassette (ABC) transporters, such as P-glycoprotein (P-gp/MDR1/ ABCB1), multidrug resistance associated protein 4 (MRP4/ ABCC4) and breast cancer resistance protein (BCRP/ABCG2), and suggest their contribution to the elimination of metabolites and xenobiotics. [11][12][13] These research achievements suggest that various transporters contribute to maintaining a suitable retinal microenvironment for the retinal-neural system.…”

Section: Introductionmentioning

confidence: 99%

Influx Transport of Cationic Drug at the Blood–Retinal Barrier: Impact on the Retinal Delivery of Neuroprotectants

Kubo

Akanuma

Hosoya

2017

Biological & Pharmaceutical Bulletin

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The retina is a tissue essential for vision, and the blood-retina barrier (BRB) helps to maintain an optimal microenvironment for the neural system in the retina. Recent findings concerning the BRB showed the involvement of transporters at the inner and outer BRB in drug and nutrient transport, suggesting their utility in the development of novel drug delivery systems to the retina. An in vitro-in vivo relationship study of permeability suggested the influx transport of verapamil, a cationic drug, across the BRB, and further in vivo and in vitro studies of cationic drugs, such as verapamil, propranolol and clonidine, revealed the involvement of carrier-mediated process in their influx transport at the BRB. Studies on substrate specificity in TR-iBRB2 cells, an in vitro model cell line of the inner BRB, suggests the involvement of novel organic cation transporter in the influx transport of cationic drugs at the inner BRB. Considering the neuroprotective effect previously reported for several cationic drugs, such as propranolol and clonidine, the study of cation transport at the BRB is widely expected to improve the treatment of retinal diseases, such as diabetic retinopathy and age-related macular degeneration.

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A phase II study of adoptive immunotherapy using dendritic cells pulsed with tumor lysate in patients with hepatocellular carcinoma

et al. 2008

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This is a phase II clinical trial investigating the safety and efficacy of intravenous vaccination with mature autologous dendritic cells (DCs) pulsed ex vivo with a liver tumor cell line lysate (HepG2) in patients with advanced hepatocellular carcinoma (HCC). HCC is an attractive target for immunotherapy as evidenced by an active recruitment of tumor-infiltrating lymphocytes that are capable of lysing autologous tumor cells in ex vivo studies. DCs are the most potent antigenpresenting cells, with the capacity to take up, process, and present tumor antigens to T cells and stimulate an immune response, thus providing a rational platform for vaccine development. Thirty-five patients with advanced HCC and not suitable for radical or loco-regional therapies received a maximum of six DC vaccinations each at 3-week intervals. In total, 134 DC infusions were administered with no significant toxicity and no evidence of autoimmunity. Twenty-five patients who received at least three vaccine infusions were assessed clinically for response. The radiologically determined disease control rate (combined partial response and stable disease >3 months) was 28%. In 17 patients the baseline serum ␣-fetoprotein (AFP) was > 1,000 ng/mL; in four of these patients, it fell to <30% of baseline following vaccination. In one patient there was a radiological partial response associated with a fall in AFP to <10% of baseline. Immune responses were assessed using an ELIspot assay of interferon-␥ (IFN-␥) release. In several cases there was induction of T cell responses to the vaccine and/or AFP following vaccination. Conclusion: Autologous DC vaccination in patients with HCC is safe and well tolerated with evidence of antitumor efficacy assessed radiologically and serologically, with generation of antigen-specific immune responses in some cases. (HEPATOLOGY 2009;49:124-132.)

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Cationic amino acid transporter 1‐mediated l‐arginine transport at the inner blood–retinal barrier

Cited by 43 publications

References 38 publications

Involvement of Cationic Amino Acid Transporter 1 in L-Arginine Transport in Rat Retinal Pericytes

Involvement of Cationic Amino Acid Transporter 1 in L-Arginine Transport in Rat Retinal Pericytes

Influx Transport of Cationic Drug at the Blood–Retinal Barrier: Impact on the Retinal Delivery of Neuroprotectants

A phase II study of adoptive immunotherapy using dendritic cells pulsed with tumor lysate in patients with hepatocellular carcinoma

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