Induction of hepatic transporters multidrug resistance-associated proteins (Mrp) 3 and 4 by clofibrate is regulated by peroxisome proliferator-activated receptor alpha.
Hepatic transporters play a vital role in the disposition of endogenous compounds and xenobiotics in the liver. The current study investigates the expression and regulation of hepatic efflux transporters in response to treatment with the peroxisome proliferator-activated receptor (PPAR)alpha agonist clofibrate (CFB). Changes in mRNA and protein levels for several hepatic transporters were assessed in male CD-1 mice after 10 days of CFB dosing (500 mg/kg i.p.). Administration of CFB up-regulated mRNA levels for breast cancer resistance protein (Bcrp) and multidrug resistance-associated proteins 3 and 4 (Mrp3 and Mrp4, respectively). Western blot analysis confirmed that CFB enhances protein expression of liver Bcrp, Mrp3, and Mrp4 in CD-1 mice. To further characterize the regulation of these hepatic transporters, CFB-mediated changes in transporter mRNA levels were assessed in wild-type (sv/129) and PPARalpha-null male mice. Wild-type mice treated with CFB showed similar changes in mRNA levels for all of these transporters, whereas the PPARalpha-null mice did not. Although protein expression of Mrp3 and Mrp4 in the wild-type mice correlated well with changes in mRNA levels, Bcrp protein was not up-regulated by CFB treatment. These results show that PPARalpha activation by CFB coordinately regulates the hepatic efflux transporters Mrp3 and Mrp4. Induction of Mrp3 and Mrp4 by CFB may alter the disposition of toxicants and xenobiotics that are substrates for these transporters.
Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, USA.
Jeffrey S
JS
Moffit
Lauren M
LM
Aleksunes
Jonathan M
JM
Maher
George L
GL
Scheffer
Curtis D
CD
Klaassen
José E
JE
Manautou
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis; D000818:Animals; D015153:Blotting, Western; D002994:Clofibrate / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis*; D047493:PPAR alpha / Q000819:agonists* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D002994:Clofibrate; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D047493:PPAR alpha; D012333:RNA, Messenger; C489540:Abcc4 protein, mouse; C501412:Abcg2 protein, mouse; C114462:multidrug resistance-associated protein 3