Protein Synthesis during Deciduoma Morphogenesis in the Rat

Abstract

The synthesis of soluble proteins during deciduoma morphogenesis in the rat uterus has been 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 (3H1-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 post. induction and again fell between Days 3 and 4 postinduction. Sodium dodecyl sulphate/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 molecular weight 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 approximate molecular weight 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. This and the observation that synthesis in the deciduoma was primarily localized in the endometrium, strongly suggested its synthesis was linked with the