Expression and localization of organic cation/carnitine transporter OCTN2 in Caco-2 cells.

Ihsan Elimrani, Karim Lahjouji, Ernest Seidman, Marie-Josee Roy, Grant A Mitchell, Ijaz Qureshi

Divisions of Medical Genetics and Gastroenterology, Research Center, Hôpital Sainte-Justine, Department of Pediatrics, Université de Montréal, Montreal, Quebec, Canada H3T 1C5.

American journal of physiology. Gastrointestinal and liver physiology 2003 May

filter terms:

l-Carnitine is derived both from dietary sources and biosynthesis. Dietary carnitine is absorbed in the small intestine and then distributed to other organs. Previous studies using Caco-2 cells demonstrated that the transport of l-carnitine in the intestine involves a carrier-mediated system. The purpose of this study was to determine whether the uptake of l-carnitine in Caco-2 cells is mediated by the recently identified organic cation/carnitine transporter (OCTN2). Kinetics of l-[(3)H]carnitine uptake were investigated with or without specific inhibitors. l-Carnitine uptake in mature cells was sodium dependent and linear with time. K(m) and V(max) values for saturable uptake were 14.07 +/- 1.70 micro M and 26.3 +/- 0.80 pmol. mg protein(-1). 6 min(-1), respectively. l-carnitine uptake was inhibited (P < 0.05-0.01) by valproate and other organic cations. Anti-OCTN2 anti bodies recognized a protein in the brush-border membrane (BBM) of Caco-2 cells with an apparent molecular mass of 60 kDa. The OCTN2 expression was confirmed by double immunostaining. Our results demonstrate that l-carnitine uptake in differentiated Caco-2 cells is primarily mediated by OCTN2, located on the BBM.

Citation

Ihsan Elimrani, Karim Lahjouji, Ernest Seidman, Marie-Josee Roy, Grant A Mitchell, Ijaz Qureshi. Expression and localization of organic cation/carnitine transporter OCTN2 in Caco-2 cells. American journal of physiology. Gastrointestinal and liver physiology. 2003 May;284(5):G863-71