title: Deregulated hepatic metabolism exacerbates impaired testosterone production in Mrp4-deficient mice.
abstract: The physiological role of multidrug resistance protein 4 (Mrp4, Abcc4) in the testes is unknown. We found that Mrp4 is expressed primarily in mouse and human Leydig cells; however, there is no current evidence that Mrp4 regulates testosterone production. We investigated its role in Leydig cells, where testosterone production is regulated by cAMP, an intracellular messenger formed when the luteinizing hormone (LH) receptor is activated. Because Mrp4 regulates cAMP, we compared testosterone levels in Mrp4(-/-) and Mrp4(+/+) mice. Young Mrp4(-/-) mice had significantly impaired gametogenesis, reduced testicular testosterone, and disruption of Leydig cell cAMP homeostasis. Both young and adult mice had impaired testosterone production. In Mrp4(-/-) primary Leydig cells treated with LH, intracellular cAMP production was impaired and cAMP-response element-binding protein (CREB) phosphorylation was strongly attenuated. Notably, expression of CREB target genes that regulate testosterone biosynthesis was reduced in Mrp4(-/-) Leydig cells in vivo. Therefore, Mrp4 is required for normal Leydig cell testosterone production. However, adult Mrp4(-/-) mice are fertile, with a normal circulating testosterone concentration. The difference is that in 3-week-old Mrp4(-/-) mice, disruption of gonadal testosterone production up-regulates hepatic Cyp2b10, a known testosterone-metabolizing enzyme. Therefore, defective testicular testosterone production de-regulates hepatic Cyp-mediated testosterone metabolism to disrupt gametogenesis. These findings have important implications for understanding the side effects of therapeutics that disrupt Mrp4 function and are reported to alter androgen production.
authors.affiliation: Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Morgan
authors.forename: Satish B
authors.initials: SB
authors.lastname: Cheepala
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Geoff
authors.initials: G
authors.lastname: Neale
authors.forename: Masashi
authors.initials: M
authors.lastname: Adachi
authors.forename: Deepa
authors.initials: D
authors.lastname: Nachagari
authors.forename: Mark
authors.initials: M
authors.lastname: Leggas
authors.forename: Wenchen
authors.initials: W
authors.lastname: Zhao
authors.forename: Kelli
authors.initials: K
authors.lastname: Boyd
authors.forename: Raman
authors.initials: R
authors.lastname: Venkataramanan
authors.forename: John D
authors.initials: JD
authors.lastname: Schuetz
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis* / Q000235:genetics; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D000072467:Cytochrome P450 Family 2; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007985:Leydig Cells / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D011974:Receptors, LH / Q000235:genetics / Q000378:metabolism; D013091:Spermatogenesis / Q000502:physiology*; D013250:Steroid Hydroxylases / Q000096:biosynthesis* / Q000235:genetics; D013739:Testosterone / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation / Q000502:physiology
chemical_list: D001189:Aryl Hydrocarbon Hydroxylases; D000242:Cyclic AMP; D017362:Cyclic AMP Response Element-Binding Protein; D000072467:Cytochrome P450 Family 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011974:Receptors, LH; D013250:Steroid Hydroxylases; D013739:Testosterone; C489540:Abcc4 protein, mouse; C492004:Creb1 protein, mouse; C101679:Cyp2b10 protein, mouse