title: Molecular cloning and characterization of a nuclear androgen receptor activated by 11-ketotestosterone.
abstract: Although 11-ketotestosterone is a potent androgen and induces male secondary sex characteristics in many teleosts, androgen receptors with high binding affinity for 11-ketotestosterone or preferential activation by 11-ketotestosterone have not been identified. So, the mechanism by which 11-ketotestosterone exhibits such high potency remains unclear. Recently we cloned the cDNA of an 11-ketotestosterone regulated protein, spiggin, from three-spined stickleback renal tissue. As spiggin is the only identified gene product regulated by 11-ketotestosterone, the stickleback kidney is ideal for determination of the mechanism of 11-ketotestosterone gene regulation. A single androgen receptor gene with two splicing variants, belonging to the androgen receptor-beta subfamily was cloned from stickleback kidney. A high affinity, saturable, single class of androgen specific binding sites, with the characteristics of an androgen receptor, was identified in renal cytosolic and nuclear fractions. Measurement of ligand binding moieties in the cytosolic and nuclear fractions as well as to the recombinant receptor revealed lower affinity for 11-ketotestosterone than for dihydrotestosterone. Treatment with different androgens did not up-regulate androgen receptor mRNA level or increase receptor abundance, suggesting that auto-regulation is not involved in differential ligand activation. However, comparison of the trans-activation potential of the stickleback androgen receptor with the human androgen receptor, in both human HepG2 cells and zebrafish ZFL cells, revealed preferential activation by 11-ketotestosterone of the stickleback receptor, but not of the human receptor. These findings demonstrate the presence of a receptor preferentially activated by 11-ketotestosterone in the three-spined stickleback, so far the only one known in any animal.
authors.affiliation: Department of Natural Science, Unit of Molecular Biology, Orebro University, SE-701 82 Orebro, Sweden. per-erik.olsson@nat.oru.se
authors.forename: Per-Erik
authors.initials: PE
authors.lastname: Olsson
authors.forename: A Håkan
authors.initials: AH
authors.lastname: Berg
authors.forename: Jonas
authors.initials: J
authors.lastname: von Hofsten
authors.forename: Birgitta
authors.initials: B
authors.lastname: Grahn
authors.forename: Anna
authors.initials: A
authors.lastname: Hellqvist
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: Johnny
authors.initials: J
authors.lastname: Karlsson
authors.forename: Carina
authors.initials: C
authors.lastname: Modig
authors.forename: Bertil
authors.initials: B
authors.lastname: Borg
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D003001:Cloning, Molecular; D013196:Dihydrotestosterone / Q000378:metabolism; D005260:Female; D029941:Fish Proteins / Q000096:biosynthesis; D005786:Gene Expression Regulation; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D011944:Receptors, Androgen / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D023701:Smegmamorpha; D013739:Testosterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D015533:Transcriptional Activation
chemical_list: D029941:Fish Proteins; D011944:Receptors, Androgen; C429543:spiggin; D013196:Dihydrotestosterone; D013739:Testosterone; C003600:11-ketotestosterone