The 4F2hc/LAT1 complex transports l-DOPA across the blood–brain barrier

• Published in: Brain research Vol. 879; no. 1; pp. 115 - 121
• Main Authors: Kageyama, Takashi, Nakamura, Masaru, Matsuo, Akinori, Yamasaki, Yasuomi, Takakura, Yoshinobu, Hashida, Mitsuru, Kanai, Yoshikatsu, Naito, Mikihiko, Tsuruo, Takashi, Minato, Nagahiro, Shimohama, Shun
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 06.10.2000; Amsterdam Elsevier; New York, NY
• Subjects: 4F2hc; Amino Acid Transport Systems; amino acid transporter; Amino Acids - metabolism; Animals; Anticonvulsants. Antiepileptics. Antiparkinson agents; Antigens, CD - genetics; Antigens, CD - metabolism; Biological and medical sciences; Biological Transport; Blood-Brain Barrier; Brain - metabolism; Capillaries - physiology; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Line; Cerebrovascular Circulation - physiology; Endothelium, Vascular - metabolism; Female; Fusion Regulatory Protein-1; l-DOPA; LAT1; Levodopa - blood; Levodopa - metabolism; Male; Medical sciences; Mice; Mice, Inbred BALB C; Neuropharmacology; Pharmacology. Drug treatments; Protein Subunits; Recombinant Proteins - metabolism; System L; l-DOPA; System L; LAT1; Cellular and molecular biology; 4F2hc; Blood–brain barrier; Endothelial cell; Biological transport; Rodentia; Central nervous system; Antiparkinson agent; Blood brain barrier; In vitro; Vertebrata; Mammalia; Cell line; Mouse; Animal; Levodopa; Carrier protein; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(00)02758-X

l-DOPA is transported across the blood–brain barrier (BBB) by an amino acid transporter, system L. Recently, it has been demonstrated that system L consists of two subunits, 4F2hc and either LAT1 or LAT2. 4F2hc/LAT1 and 4F2hc/LAT2 show different transport characteristics, while their distribution in the brain has not been determined. To clarify whether 4F2hc/LAT1 participates in l-DOPA transport across the BBB, we first examined the expression of 4F2hc/LAT1 in the mouse brain capillary endothelial cell line, MBEC4, as an in vitro BBB model. Northern hybridization and immunoblotting revealed that both 4F2hc and LAT1 are expressed and form a heterodimer in MBEC4 cells. To confirm whether 4F2hc/LAT1 acts as system L to transport l-DOPA, we characterized l-DOPA uptake into the cells. The uptake process was time-dependent, temperature-sensitive, and Na +-independent. Neutral amino acids with bulky side chains and a bicyclic amino acid, 2-aminobicyclo-[2,2,1]-heptane-2-carboxylic acid (BCH), inhibited l-DOPA uptake into MBEC4 cells to a great extent, while an acidic amino acid, basic amino acids, and glycine had no effect. Other neutral amino acids, such as alanine, asparagine, glutamine, serine, and threonine inhibited l-DOPA uptake by 40–70% at most. These characteristics are more compatible with those of 4F2hc/LAT1, rather than those of 4F2hc/LAT2. Finally, immunohistochemistry with anti-LAT1 antibody demonstrated that LAT1 is predominantly expressed in the microvessels of the central nervous system. This is the first report showing that the 4F2hc/LAT1 complex participates in l-DOPA transport across the BBB.