Testosterone regulates tissue-specific changes in the binding of a 47-kilodalton protein to a highly conserved sequence in the 3' untranslated region of epidermal growth factor messenger ribonucleic acid.
Epidermal growth factor (EGF) transcripts that use the terminal polyadenylation signal display a dramatic sex difference in the pattern of polyadenylation in the murine submaxillary gland (SMG), whereas those in the kidney do not. It takes 3 days before testosterone treatment begins to change the polyadenylation pattern in female SMG to resemble the male pattern, a finding that supports previous suggestions that posttranscriptional mechanisms are involved in regulating EGF expression. The conservation of a unique 23-b sequence centered on the terminal polyadenylation signal in all published mammalian EGF sequences suggested that trans-acting factors involved in EGF messenger RNA (mRNA) metabolism might bind to this sequence. To investigate this, we prepared 32P-RNA containing the 3' terminal EGF 23-b sequence plus a short poly-A tail, and incubated it with SMG cytosol. Cytosol retarded the electrophoretic mobility of this RNA as a single prominent band on 8% PAGE, and by UV-cross-linking, a single prominent 47-kDa protein was detected on 10% SDS-PAGE. Trypsin abolished both the gel-retarding and cross-linking activities. Cytosol from female SMGs contained approximately 8 times more of both the RNA binding activities than male cytosol. Injecting testosterone (200 microg QOD) into female mice altered both the RNA binding activities in a biphasic fashion, initially increasing them by about 40% at 2 days, then decreasing them by about 65% > or = 5 days, reaching male levels. Kidney cytosol contained both RNA binding activities but displayed neither sexual dimorphism nor testosterone-responsiveness. The tissue-specific testosterone-dependent changes observed in the 47-kDa protein occur before the increase in EGF mRNA levels and before the change in EGF mRNA polyad-enylation, so this cytosolic protein could be a trans-acting factor involved in EGF polyadenylation.
Sheflin
L G
LG
The Research Service at the VA Western New York Healthcare System, Buffalo, New York 14215, USA.
Brooks
E M
EM
Spaulding
S W
SW
D000469:Alkaline Phosphatase / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D018076:DNA, Complementary; D066246:ErbB Receptors / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D012727:Sex Characteristics; D013363:Submandibular Gland / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology*
D018076:DNA, Complementary; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013739:Testosterone; D066246:ErbB Receptors; D000469:Alkaline Phosphatase