title: L-type amino acid transporter-1 expressed in human astrocytomas, U343MGa.
abstract: LAT1 (L-type amino acid transporter 1), one of the L-type amino acid transporters, transports the branched and aromatic amino acids. LAT1 requires the heavy chain of 4F2 antigen (4F2hc) for the functional expression as an amino acid transporter. The expression of this transporter is up-regulated in tumor cells and rapidly-growing cells to support their proliferation. Here, we studied the expression of LAT1 and 4F2hc in human cultured cells by real-time PCR and Western blot, and found that human brain astrocytomas, U343MGa, highly expressed LAT1 and 4F2hc mRNAs and proteins. The uptake of [14C]leucine by U343MGa cells is Na+-independent and inhibited by BCH (2-amino-2-norbornane carboxylic acid), and branched and aromatic amino acids, indicating that the LAT1 is expressed at the cell surface. Pulse chase labeling and surface labeling experiments of this cell line indicate that the protein synthesis of LAT1 and 4F2hc is slow, however, the heterodimeric complex assembled in the cells is very stable, and that the disulfide bond between the LAT1 and 4F2hc is not directly involved in the stability of the heterodimer.
authors.affiliation: Department of Molecular Physiology, College of Information Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan. ashinji@is.ritsumei.ac.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Asano
authors.forename: Megumi
authors.initials: M
authors.lastname: Kameyama
authors.forename: Ayako
authors.initials: A
authors.lastname: Oura
authors.forename: Anna
authors.initials: A
authors.lastname: Morisato
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Arthit
authors.initials: A
authors.lastname: Chairoungdua
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endou
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Kanai
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002250:Carbon Radioisotopes; D002460:Cell Line; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D027282:Fusion Regulatory Protein 1, Heavy Chain / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D019073:HT29 Cells; D006367:HeLa Cells; D006801:Humans; D027283:Large Neutral Amino Acid-Transporter 1 / Q000235:genetics* / Q000378:metabolism; D007930:Leucine / Q000378:metabolism / Q000493:pharmacokinetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000235:genetics
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; D027282:Fusion Regulatory Protein 1, Heavy Chain; D027283:Large Neutral Amino Acid-Transporter 1; D012333:RNA, Messenger; D007930:Leucine