title: Cloning, expression and enzyme activity analysis of testicular 11beta-hydroxysteroid dehydrogenase during seasonal cycle and after hCG induction in air-breathing catfish Clarias gariepinus.
abstract: A full-length cDNA encoding 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) was cloned from testis of air-breathing catfish, Clarias gariepinus which showed high sequence homology to zebrafish and eel. The open reading frame of 11beta-HSD2 was then transfected to COS-7 cells, which converted 11beta-hydroxytestosterone (11-OHT) to 11-ketotestosterone (11-KT). Using NAD(+), 11beta-HSD2 from testicular microsomes oxidized 11-OHT with apparent K(m) 56+/-4nM and V(max) 55+/-6pmol/h/mgprotein values. Tissue distribution analysis revealed prominent expression in testis, anterior kidney, liver and gills. Expression of 11beta-HSD2 in testis and serum levels of 11-KT were high in the prespawning phase. Administration of human chorionic gonadotropin (hCG) during prespawning and resting phases revealed initial rise in 11beta-HSD2 transcript at 4h followed by gradual increase at 8h, 12h and peaking at 24h, only in testis of prespawning phase. Rate of conversion of 11-OHT to 11-KT by testicular microsomes during different testicular phases and after hCG administration corroborated well with the expression of 11beta-HSD2. Ontogeny study indicated that this enzyme is expressed during testicular development. Thus the spatio-temporal expression supported with putative dehydrogenase activity and circulating 11-KT levels clearly suggest a major role for 11beta-HSD2 during testicular differentiation and seasonal testicular cycle in catfish.
authors.affiliation: Department of Animal Sciences, School of Life Sciences-Centre for Advanced Studies, University of Hyderabad, P. O. Central University, Hyderabad 500 046, Andhra Pradesh, India.
authors.forename: M K
authors.initials: MK
authors.lastname: Rasheeda
authors.forename: H
authors.initials: H
authors.lastname: Kagawa
authors.forename: R
authors.initials: R
authors.lastname: Kirubagaran
authors.forename: A
authors.initials: A
authors.lastname: Dutta-Gupta
authors.forename: B
authors.initials: B
authors.lastname: Senthilkumaran
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002397:Catfishes / Q000235:genetics* / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D008297:Male; D012621:Seasons; D013737:Testis / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2