High- and low-affinity transport of L-leucine and L-DOPA by the hetero amino acid exchangers LAT1 and LAT2 in LLC-PK1 renal cells

被引:28
作者
Soares-da-Silva, P [1 ]
Serrao, MP [1 ]
机构
[1] Univ Porto, Fac Med, Inst Pharmacol & Therapeut, P-4200 Oporto, Portugal
关键词
renal dopaminergic system; sodium intake;
D O I
10.1152/ajprenal.00030.2004
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The present study examined the functional characteristics of the inward and outward L-[(14)C] DOPA and L-[(14)C] leucine transporters in LLC-PK(1) cells. Uptake was initiated by the addition of Hanks' medium with a given concentration of L-[(14)C] DOPA or L-[(14)C] leucine. Saturation experiments were performed in cells incubated for 6 min with 0.25 muM concentration of the substrates in the absence and the presence of increasing concentrations of the nonlabeled substrates. Fractional outflow of intracellular L-[(14)C] DOPA or L-[(14)C] leucine was evaluated in cells loaded with 2.5 muM L-[(14)C] DOPA or 1 M L-[(14)C] leucine for 6 min and then the corresponding efflux was monitored over 24 min. The high-affinity (K(m) = 5.1 muM) uptake of L-[(14)C] leucine and the low-affinity (K(m) = 120.0 muM) uptake of L-[(14)C] DOPA were largely promoted through a Na(+)-independent transporter. The uptake of the substrates was insensitive to N-(methylamino)-isobutyric acid but competitively inhibited by 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH). L- And D-neutral amino acids, but not acidic and basic amino acids, markedly inhibited L-[(14)C] DOPA and L-[(14)C] leucine accumulation. The uptake of L-[(14)C] leucine was a pH-insensitive process, whereas that of L-[(14)C] DOPA was sensitive to pH. The efflux of L-[(14)C] DOPA and L-[(14)C] leucine was markedly increased ( P < 0.05) by L- cysteine, L-leucine, BCH, and L-DOPA but not by L-arginine. RT-PCR detected LAT1 and LAT2 transcripts in LLC-PK(1) cells. It is concluded that LLC-PK(1) cells express both LAT1 and LAT2 transcripts and transport L-[(14)C] leucine through the Na(+)-independent pH-insensitive and high-affinity LAT1 transporter, whereas L-[(14)C] DOPA is mainly transported through the Na(+)-independent pH-insensitive and low-affinity LAT2 transporter and a minor component through a Na(+)-dependent transporter.
引用
收藏
页码:F252 / F261
页数:10
相关论文
共 48 条
[21]   The 4F2hc/LAT1 complex transports L-DOPA across the blood-brain barrier [J].
Kageyama, T ;
Nakamura, M ;
Matsuo, A ;
Yamasaki, Y ;
Takakura, Y ;
Hashida, M ;
Kanai, Y ;
Naito, M ;
Tsuruo, T ;
Minato, N ;
Shimohama, S .
BRAIN RESEARCH, 2000, 879 (1-2) :115-121
[22]   Expression cloning and characterization of a transporter for large neutral amino acids activated by the heavy chain of 4F2 antigen (CD98) [J].
Kanai, Y ;
Segawa, H ;
Miyamoto, K ;
Uchino, H ;
Takeda, E ;
Endou, H .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1998, 273 (37) :23629-23632
[23]   DOPAMINE AND THE KIDNEY - 10 YEARS ON [J].
LEE, MR .
CLINICAL SCIENCE, 1993, 84 (04) :357-375
[24]   Salt intake and sensitivity of intestinal and renal Na+K+- ATPase to inhibition by dopamine in spontaneous hypertensive and Wistar-Kyoto rats [J].
Lucas-Teixeira, VA ;
Vieira-Coelho, MA ;
Serrao, P ;
Pestana, M ;
Soares-da-Silva, P .
CLINICAL AND EXPERIMENTAL HYPERTENSION, 2000, 22 (05) :455-469
[25]   EAAT1 is involved in transport of L-glutamate during differentiation of the Caco-2 cell line [J].
Mordrelle, A ;
Jullian, E ;
Costa, C ;
Cormet-Boyaka, E ;
Benamouzig, R ;
Tomé, D ;
Huneau, JF .
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY, 2000, 279 (02) :G366-G373
[26]   Molecular biology of mammalian plasma membrane amino acid transporters [J].
Palacin, M ;
Estevez, R ;
Bertran, J ;
Zorzano, A .
PHYSIOLOGICAL REVIEWS, 1998, 78 (04) :969-1054
[27]   Identification of a membrane protein, LAT-2, that co-expresses with 4F2 heavy chain, an L-type amino acid transport activity with broad specificity for small and large zwitterionic amino acids [J].
Pineda, M ;
Fernández, E ;
Torrents, D ;
Estévez, R ;
López, C ;
Camps, M ;
Lloberas, J ;
Zorzano, A ;
Palacín, M .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (28) :19738-19744
[28]   Organ-specific overexpression of renal LAT2 and enhanced tubular L-DOPA uptake precede the onset of hypertension [J].
Pinho, MJ ;
Gomes, P ;
Serrao, MP ;
Bonifácio, MJ ;
Soares-da-Silva, P .
HYPERTENSION, 2003, 42 (04) :613-618
[29]   Human LAT1, a subunit of system L amino acid transporter: Molecular cloning and transport function [J].
Prasad, PD ;
Wang, HP ;
Huang, W ;
Kekuda, R ;
Rajan, DP ;
Leibach, FH ;
Ganapathy, V .
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 1999, 255 (02) :283-288
[30]   LAT2, a new basolateral 4F2hc/CD98-associated amino acid transporter of kidney and intestine [J].
Rossier, G ;
Meier, C ;
Bauch, C ;
Summa, V ;
Sordat, B ;
Verrey, F ;
Kühn, LC .
JOURNAL OF BIOLOGICAL CHEMISTRY, 1999, 274 (49) :34948-34954