Cloning of the dog bile salt export pump (BSEP; ABCB11) and functional comparison with the human and rat proteins

✍ Scribed by Hikaru Yabuuchi; Kenji Tanaka; Miyako Maeda; Masaaki Takemura; Masaki Oka; Rikiya Ohashi; Ikumi Tamai

• Book ID: 102755719
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 512 KB
• Volume: 29
• Category: Article
• ISSN: 0142-2782
• DOI: 10.1002/bdd.629

✦ Synopsis

Abstract

The dog bile salt export pump (BSEP; ABCB11) was cloned and expressed in a Sf9 insect cell system. The deduced amino acid sequence encodes a 1325‐amino‐acid protein, which shows 89.4% and 80.2% homology with human BSEP and rat Bsep, respectively. The transcript of the dog Bsep gene was detected at a high level in liver, but not other tissues, by quantitative RT‐PCR. The BSEP‐expressing membrane vesicles isolated from Sf9 cells exhibited saturable uptake of [^3^H]taurocholic acid with Michaelis constants (K~m~) of 33.7, 22.2 and 19.9 µM for the dog, rat and human transporters, respectively. The uptake of [^3^H]taurocholic acid by all three transporters was significantly inhibited by troglitazone, glibenclamide, and other several inhibitors, while pravastatin inhibited dog Bsep and human BSEP, but not rat Bsep at 100 µM. The IC~50~ of troglitazone for dog Bsep, human BSEP, and rat Bsep were 32, 20, and 60 µM, and those of pravastatin were 441, 240 and >1,000 µM, respectively. In conclusion, while dog Bsep shows similar ATP‐dependent bile acid transport characteristics to human BSEP and rat Bsep, there is a species difference in affinity for drugs such as pravastatin and troglitazone. Copyright © 2008 John Wiley & Sons, Ltd.