Forskolin-resistant Y1 adrenal cell mutants are deficient in adenylyl cyclase type 4.
Four mutant clones independently derived from the Y1 mouse adrenocortical tumor cell line have adenylyl cyclase (AC) activities that are resistant to forskolin, a direct activator of AC. In this study the AC isoform composition of the forskolin-resistant mutants was examined in order to explore the underlying basis for the resistance to forskolin. As determined by Western blot and RT-PCR analysis, the four forskolin-resistant mutants all were deficient in AC-4; the levels of other AC isoforms (AC-1, AC-3 and AC-5/6) were comparable to the levels in parent Y1 cells. Transfection of one of the mutant clones with an AC-4 expression vector increased forskolin-stimulated cAMP signaling, and restored forskolin-induced changes in cell morphology and growth. Taken together, these observations indicate that AC-4 deficiency is a hallmark of the forskolin-resistant phenotype of these mutants and suggest that AC-4 is an important target of forskolin action in the Y1 adrenal cell line.
Al-Hakim
Abdallah
A
Department of Pharmacology, University of Toronto, Toronto, Ont., Canada M5G 1L6.
Rui
Xianliang
X
Tsao
Jennivine
J
Albert
Paul R
PR
Schimmer
Bernard P
BP
D000262:Adenylyl Cyclases / Q000032:analysis / Q000172:deficiency* / Q000502:physiology; D000306:Adrenal Cortex Neoplasms / Q000235:genetics / Q000473:pathology*; D000818:Animals; D002455:Cell Division; D045744:Cell Line, Tumor; D048429:Cell Size; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D051379:Mice; D009154:Mutation; D020033:Protein Isoforms / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis
D020033:Protein Isoforms; D012333:RNA, Messenger; D005576:Colforsin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C406262:adenylyl cyclase 4