Rapid regulation of c-myc protooncogene expression by progesterone in the avian oviduct.
The mRNA levels of genes known to be regulated by sex steroids are not altered until 1 hr or longer after steroid treatment, although the steroid receptor complexes are bound to nuclear acceptor sites within 5 min. In a search for early regulation of gene transcription, total chick oviduct RNA was isolated at various times after injection (i.p.) of progesterone and analyzed for c-myc expression. Levels of c-myc mRNA began to decrease in response to progesterone by 10 min after injection. The mRNA levels continued to decrease, reached a 70% reduction at 30 min, and returned to control values by 8 hr after steroid injection. Changes in alpha-tubulin mRNA levels were markedly less in these same RNA preparations. The effect was dependent on the dose of the steroid and was target-tissue specific. These changes occurred much more rapidly than changes in egg-white protein mRNA levels. Vehicle alone did not alter c-myc mRNA levels. Early regulated genes such as c-myc may represent the initial site of action of steroid receptors in the genome.
Fink
K L
KL
Department of Biochemistry, Mayo Clinic, Rochester, MN 55905.
Wieben
E D
ED
Woloschak
G E
GE
Spelsberg
T C
TC
D000818:Animals; D004054:Diethylstilbestrol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation / Q000187:drug effects*; D010057:Oviducts / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000378:metabolism; D014404:Tubulin / Q000235:genetics
D012333:RNA, Messenger; D014404:Tubulin; D011374:Progesterone; D004054:Diethylstilbestrol