RT Journal Article
SR Electronic
T1 PDZK1 Regulates Breast Cancer Resistance Protein in Small Intestine
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 2148
OP 2154
DO 10.1124/dmd.111.040295
VO 39
IS 11
A1 Takuya Shimizu
A1 Tomoko Sugiura
A1 Tomohiko Wakayama
A1 Ai Kijima
A1 Noritaka Nakamichi
A1 Shoichi Iseki
A1 David L. Silver
A1 Yukio Kato
YR 2011
UL http://dmd.aspetjournals.org/content/39/11/2148.abstract
AB Transporter adaptor protein PDZK1 regulates several influx transporters for xenobiotics and nutrients in small intestine, and their expression on the apical membrane is diminished in pdzk1 gene knockout [pdzk1(−/−)] mice. In the present study, we initially attempted to use pdzk1(−/−) mice to functionally identify influx transporters responsible for intestinal absorption of cimetidine. Contrary to our expectation, the plasma concentration of cimetidine after oral administration to pdzk1(−/−) mice was higher than that in wild-type mice, and the double peaks of plasma concentration found in wild-type mice were not observed in pdzk1(−/−) mice. Western blot analysis of intestinal brush-border membranes revealed that expression of breast cancer resistance protein (BCRP) but not of P-glycoprotein is reduced in pdzk1(−/−) mice. This result was compatible with the reduction of apical localization of BCRP in pdzk1(−/−) mice assessed by immunohistochemical analysis. Transcellular transport of cimetidine in the basal-to-apical direction in Madin-Darby canine kidney II (MDCKII) cells stably expressing both BCRP and PDZK1 (MDCKII/BCRP/PDZK1) was higher than that in MDCKII cells stably expressing BCRP (MDCKII/BCRP) cells. Moreover, MDCKII/BCRP/PDZK1 cells are more resistant than MDCKII/BCRP cells to the cytotoxicity of the anticancer agent 7-ethyl-10-hydroxycamptothecin (SN-38), which is a substrate of BCRP. These results were consistent with the higher expression of BCRP on apical membranes in MDCKII/BCRP/PDZK1 cells. Pull-down and immunoprecipitation studies revealed a physical interaction between BCRP and PDZK1. Taken together, these findings demonstrate that PDZK1 plays a pivotal role in the apical localization of BCRP. This is the first identification of a regulatory protein that physically interacts with and regulates BCRP in small intestine in vivo.