Effects ofTestosterone onMessenger Ribonucleic Acidand Protein Synthesis inRatSeminal Vesicle

Inaprevious report [Higgins etal. (1976) Biochem. J.158,271-282] wedescribed theeffects ofalterations inandrogen status onthesynthesis oftwobasic secretory proteins oftherat seminal vesicle. Inthepresent paperweexamine theeffects oftestosterone onthe activity ofmRNA intheseminal vesicle. Total cellular poly(A)-rich RNA wasisolated andtranslated inacell-free system prepared fromwheatgerm.Translation products wereseparated ondenaturing polyacrylamide gels andtheprotein bandscorresponding tothetwobasic secretory proteins wereidentified immunologically. Incorporation ofradioactive methionine into these bandswastaken asameasure oftheindividual mRNA activities. Total mRNA activity wasestimated byradioactivity intotal acidprecipitable material. Theresults showthat 1to2weeksafter castration theactivities of mRNA molecules forthebasic secretory proteins weredecreased 10-20-fold on atissue basis. Testosterone given invivo rapidly andsubstantially restores mRNA activity tonormal. Sincethese changes correlate closely withvariations intheratesof synthesis ofthesecretory proteins inwholecells itsuggests thatandrogenic steroids control protein synthesis chiefly viamRNA availability. Inthis respect their action resembles thoseofothersteroid hormones acting inother systems. However, these effects oftestosterone onthemRNA molecules forthemajor secretory proteins could not bedistinguished fromthose ontotal mRNA.Thustheproportion ofthetotal mRNA population accounted forbythetwospecific mRNA molecules showed less thana2-fold variation withandrogen status. Similarly thetwosecretory proteins always accounted for25-33% ofgeneral protein synthesis. Thisisinsharp contrast withthemarkedly differential effects ofothersteroid hormones controlling synthesis ofmajorproteins inother well-studied systems. We interpret ourresults asindicating thattestosterone regulates themRNA population oftheseminal vesicle asawhole.