PROTEIN-SYNTHESIS DURING DECIDUOMA MORPHOGENESIS IN THE RAT

The synthesis of soluble proteins during deciduoma morphogenesis in the rat uterus was examined. Deciduoma were induced in Day 5 pregnant rats by intraluminal instillation of oil and uterine tissue was collected up to 5 days postinduction. Total soluble proteins were labeled with [3H]-leucine during in vitro incubation of uterus tissue. The specific activity of total soluble proteins increased significantly on Day 1 postinduction, returned to the control on Day 2 postinduction and again fell between Days 3-4 postinduction. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis resolved deciduomal soluble proteins into 19 polypeptide bands. During deciduoma morphogenesis, major differences in protein profiles were observed. A protein of approximate MW 140,000-145,000 daltons (referred to as band 3) which was not detectable on Days 0-2 postinduction increased to a maximum concentration on Day 5 postinduction. A decrease in concentration of a protein of .apprx. MW 160,000-165,000 daltons (referred to as band 2) was observed from Day 1-5 postinduction. These changes were reflected in radioactivity profiles of sliced gels. Electrophoretic analysis of serum over the period discounted a contribution of serum proteins to the alterations in uterine soluble protein profiles. Band 3 protein was not synthesized or detectable in contralateral, nondecidualized uterine tissue. In uteri from pregnant animals, band 3 protein was synthesized by implant site tissue. Synthesis in the deciduoma was primarily localized in the endometrium, strongly suggesting that its synthesis was linked with the processes of decidualization. Glycoprotein identity was indicated.