Functional Expression of Organic Cation/carnitine Transporter 2 (OCTN2/SLC22A5) in Human Brain Capillary Endothelial Cell Line hCMEC/D3, a Human Blood-brain Barrier Model

• Published in: DRUG METABOLISM AND PHARMACOKINETICS Vol. 29; no. 1; pp. 69 - 74
• Main Authors: Okura, Takashi, Kato, Sayaka, Deguchi, Yoshiharu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 2014; Japanese Society for the Study of Xenobiotics
• Subjects: blood-brain barrier; Blood-Brain Barrier - metabolism; Brain - blood supply; Capillaries - metabolism; carnitine; Carnitine - metabolism; Cell Line; Endothelial Cells - metabolism; Gene Silencing; hCMEC/D3 cells; Humans; organic cation transport; Organic Cation Transport Proteins - genetics; Organic Cation Transport Proteins - metabolism; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; SLC22; small interfering RNA; Solute Carrier Family 22 Member 5; blood-brain barrier; carnitine; small interfering RNA; hCMEC/D3 cells; organic cation transport; SLC22
• ISSN: 1347-4367; 1880-0920; 1880-0920
• DOI: 10.2133/dmpk.DMPK-13-RG-058

The aim of this study was to examine whether organic cation/carnitine transporter 2 (OCTN2/SLC22A5) plays a role in the human blood-brain barrier (BBB) by evaluating its functional activity in human brain endothelial cells (hCMEC/D3), which are considered to be a model of the BBB. The uptake of [3H]L-carnitine by hCMEC/D3 cells was time-, extracellular sodium- and concentration-dependent, with a Km value of 15.7 μΜ. These results are consistent with the properties of OCTN2-mediated L-carnitine transport. hCMEC/D3 cells showed relatively high expression of OCTN2 mRNA, and this expression was effectively decreased at 24-72h after lipofection of cells with OCTN2 siRNA under optimized conditions. [3H]L-Carnitine uptake was dramatically suppressed by silencing of the OCTN2 gene. The inhibitory effect of OCTN2 gene silencing was similar to that of an excess amount of unlabeled L-carnitine. These results indicate that OCTN2 is involved in L-carnitine transport at the human BBB.