title: Expression of adenylyl cyclase-4 (AC-4) in Y1 and forskolin-resistant adrenal cells.
abstract: Forskolin-resistant mutants of a mouse adrenocortical cell line present a complex phenotype in which adenylyl cyclase (AC) is resistant to activation by forskolin and by ACTH. ACTH-resistance results from a defect affecting transcription of the ACTH receptor and can be overcome by transfecting mutant cells with expression vectors encoding G beta/gamma. Forskolin-resistance results from an AC-4 deficiency. We now demonstrate that the AC-4 deficiency in forskolin-resistant mutants results from a transcription defect affecting the promoter activity of the AC-4 gene. Furthermore, the underlying defect leading to AC-4 deficiency and forskolin-resistance can be overcome by transfection of mutant clones with expression vectors encoding G beta/gamma. These data support our hypothesis that AC-4 is a preferred target of forskolin action in Y1 cells, demonstrate novel roles for G beta/gamma in gene expression and indicate that a common underlying defect, suppressible by G beta/gamma, accounts for both the resistance to ACTH and to forskolin.
authors.affiliation: Banting and Best Department of Medical Research, University of Toronto, 112 College Street, Toronto, Ont., Canada M5G 1L6.
authors.forename: Xianliang
authors.initials: X
authors.lastname: Rui
authors.forename: Abdallah
authors.initials: A
authors.lastname: Al-Hakim
authors.forename: Jennivine
authors.initials: J
authors.lastname: Tsao
authors.forename: Paul R
authors.initials: PR
authors.lastname: Albert
authors.forename: Bernard P
authors.initials: BP
authors.lastname: Schimmer
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics / Q000502:physiology*; D000306:Adrenal Cortex Neoplasms / Q000235:genetics / Q000473:pathology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004351:Drug Resistance; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018043:Receptors, Corticotropin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D018043:Receptors, Corticotropin; D005576:Colforsin; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases; C406262:adenylyl cyclase 4