Retinoic acid, dibutyryl-cAMP, and differentiation affect the expression of retinoic acid receptors in F9 cells.
Expression of the retinoic acid receptors alpha and beta (RAR-alpha and RAR-beta) was examined in F9 cells, an embryonal carcinoma cell model established for the study of retinoid metabolism and function. Addition of retinoic acid to F9 cell medium caused a dose-dependent increase in RAR-beta mRNA within 3 hr that reached 5- to 30-fold greater than the constitutively expressed mRNA by 24 hr. The elevation in mRNA resulted from increased transcription, as demonstrated by nuclear run-on transcription, did not require protein synthesis, and required the constant presence of retinoic acid. N6,O2'-Dibutyryl-cAMP attenuated the retinoic acid-induced increase in RAR-beta mRNA by a post-transcriptional mechanism. In contrast, RAR-alpha mRNA in F9 stem cells was affected less (1.2- to 1.4-fold increase) by retinoic acid and decreased 3-fold transiently when fresh serum was added to the medium. Differentiation of F9 cells resulted in increased steady-state levels of RAR-beta mRNA in primitive (4-fold), parietal (3-fold), and visceral (8-fold) endoderm but decreased steady-state levels of RAR-alpha mRNA in primitive (2-fold), parietal (3-fold), and visceral (1.4-fold) endoderm. These data demonstrate that RAR-beta is a primary target gene for retinoic acid in a characterized model of retinoid function, indicate that constitutive expression of both RAR-beta and RAR-alpha is dependent upon the differentiation state, and suggest hormonal modulation of RAR-beta by cAMP and modulation of RAR-alpha by serum factors. These results distinguish the effects of serum, cAMP, and retinoic acid on the expression of RAR from the effects mediated by differentiation.
Martin
C A
CA
Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14214.
Ziegler
L M
LM
Napoli
J L
JL
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics*; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015342:DNA Probes; D015870:Gene Expression / Q000187:drug effects; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D018168:Receptors, Retinoic Acid; D015183:Restriction Mapping; D013724:Teratoma; D014158:Transcription, Genetic / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*
D002352:Carrier Proteins; D015342:DNA Probes; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D014212:Tretinoin; D003994:Bucladesine