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Functional regulation of Na + ‐dependent neutral amino acid transporter ASCT2 by S ‐nitrosothiols and nitric oxide in Caco‐2 cells
Author(s) -
Uchiyama Tomomi,
Matsuda Yasuyuki,
Wada Miyuki,
Takahashi Satoru,
Fujita Takuya
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.03.065
Subject(s) - chemistry , nitric oxide , amino acid , alanine , snap , transporter , homoserine , biochemistry , biophysics , cycloheximide , protein biosynthesis , biology , gene , quorum sensing , computer graphics (images) , organic chemistry , virulence , computer science
We describe the regulation mechanisms of the Na + ‐dependent neutral amino acid transporter ASCT2 via nitric oxide (NO) in the human intestinal cell line, Caco‐2. Exposure of Caco‐2 cells to S ‐nitrosothiol, such as S ‐nitroso‐ N ‐acetyl‐ dl ‐penicillamine (SNAP) and S ‐nitrosoglutathione, and the NO‐donor, NOC12, concentration‐ and time‐dependently increased Na + ‐dependent alanine uptake. Kinetic analyses indicated that SNAP increases the maximal velocity ( V max ) of Na + ‐dependent alanine uptake in Caco‐2 cells without affecting the Michaelis–Menten constant ( K t ). The stimulatory effect was partially eliminated by actinomycin D and cycloheximide. Increased Na + ‐dependent alanine uptake by SNAP was partially abolished by the NO scavengers, 2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl 3‐oxide sodium salt (carboxy‐PTIO) and N ‐(dithiocarboxy)sarcosine disodium salts (DTCS), as well as the NADPH oxidase inhibitor, diphenyleneiodonium. RT‐PCR revealed that Caco‐2 cells expressed the Na + ‐dependent neutral amino acid transporter ASCT2, but not the other Na + ‐dependent neutral amino acid transporters ATB 0,+ and B 0 AT1. These results suggested that functional up‐regulation of ASCT2 by SNAP might be partially associated with an increase in the density of transporter protein via de novo synthesis.