Related Experiment Videos
Functional analysis of ABCA8, a new drug transporter
Shuichi Tsuruoka1, Kenichi Ishibashi, Hisashi Yamamoto
1Department of Clinical Pharmacology, Jichi Medical School, 3311 Yakushiji, Minamikawachi, Kawachi, Tochigi 329-0498, Japan. tsuru@jichi.ac.jp
Biochemical and Biophysical Research Communications
|October 16, 2002
Summary
Human EST KIAA0822/ABCA8, an ABC superfamily transporter, effectively accumulates xenobiotics like estradiol-beta-glucuronide. This ATP-dependent transport is inhibited by ABCC2/MRP-2 substrates, identifying ABCA8 as a novel xenobiotic transporter.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- The ABC (ATP-binding cassette) superfamily comprises transporters crucial for cellular efflux.
- Understanding novel ABC transporters like KIAA0822/ABCA8 is vital for xenobiotic transport research.
Purpose of the Study:
- To investigate the transport capabilities of human EST KIAA0822/ABCA8 in Xenopus laevis oocytes.
- To characterize the substrates and transport mechanism of ABCA8.
Main Methods:
- Xenopus laevis oocyte expression system was used to study KIAA0822/ABCA8.
- Accumulation assays were performed using radiolabeled substrates, including [14C]estradiol-beta-glucuronide.
- Inhibition studies with known transporter substrates/inhibitors were conducted.
- Northern blot analysis assessed gene expression patterns.
Main Results:
- KIAA0822/ABCA8 significantly accumulated substrates of ABCC2/MRP-2 and organic anion transporters (OATs), but not tetraethylammonium or doxorubicin.
- [14C]estradiol-beta-glucuronide transport was ATP-dependent with estimated K(m) of 30.4 microM and V(max) of 66.9 pmol/h/egg.
- Transport was inhibited by ABCC2/MRP-2 inhibitors, but not by those for organic cation transporters or MDR-1.
- Northern blot revealed expression in heart, skeletal muscle, and liver.
Conclusions:
- ABCA8 functions as an ATP-dependent xenobiotic transporter.
- Its substrate specificity overlaps with ABCC2/MRP-2 and OATs.
- ABCA8 represents a newly identified member of the xenobiotic transporter ABC-subfamily.