| First Author | Xiang J | Year | 2006 |
| Journal | Brain Res | Volume | 1122 |
| Issue | 1 | Pages | 18-23 |
| PubMed ID | 17034769 | Mgi Jnum | J:115281 |
| Mgi Id | MGI:3691267 | Doi | 10.1016/j.brainres.2006.09.013 |
| Citation | Xiang J, et al. (2006) PEPT2-mediated transport of 5-aminolevulinic acid and carnosine in astrocytes. Brain Res 1122(1):18-23 |
| abstractText | 5-Aminolevulinic acid (ALA) and carnosine have important physiological and pathophysiological roles in the CNS. Both are substrates for the proton-coupled oligopeptide transporter PEPT2. The purpose of the current study was to determine the importance of PEPT2 in the uptake of ALA and carnosine in rat and mouse (PEPT2(+/+) and PEPT2(-/-)) cultured neonatal astrocytes. Although neonatal astrocytes are known to express PEPT2, its quantitative importance in the transport of these compounds is not known. [(14)C]ALA uptake in neonatal rat astrocytes was inhibited by dipeptides, an alpha-amino containing cephalosporin (which is a PEPT2 substrate) but was not affected by a non-amino containing cephalosporin (which is not a PEPT2 substrate). Uptake was pH sensitive as expected from a proton-coupled transporter and was saturable (V(max)=715+/-29 pmol/mg/min, K(m)=606+/-14 muM). [(3)H]Carnosine uptake in neonatal rat astrocytes was inhibited by dipeptides but not by histidine (a substrate for the peptide/histidine transporters PHT1 and PHT2) and also showed saturable transport (V(max)=447+/-23 pmol/mg/min, K(m)=43+/-5.5 muM). Neonatal astrocytes from PEPT2(-/-) mice had a 62% reduction in [(14)C]ALA uptake and a 92% reduction in [(3)H]carnosine uptake compared to PEPT2(+/+) mice. These results demonstrate that PEPT2 is the primary transporter responsible for the astrocytic uptake of ALA and carnosine. |
