SELENOPROTEIN-P EXPRESSION IN LIVER, UTERUS AND PLACENTA DURING LATE PREGNANCY

To identify genes that exhibit increased expression in the placenta du ring late pregnancy, the technique of differential cDNA library screen ing was used to isolate a clone subsequently identified as the 3' untr anslated region of the mouse selenoprotein p gene. Random primed, radi olabelled cDNA probes were constructed from this clone and these probe s were used to conduct Northern hybridizations against total RNA purif ied from mouse placenta, liver (maternal and fetal) and uterus collect ed sequentially during the latter third of pregnancy. Signal is presen t in the placenta and beginning 4 days before birth, the level of mess age increases, reaching maximal levels at term. The level of expressio n in the placenta at maximum is approximately 25 per dent of that obse rved in adult liver. In liver obtained from pregnant females, the leve l of message is increased compared to nonpregnant adults, but returns to normal shortly after birth. Message if also found in the fetal live r beginning at 4 days before birth and exhibits a pattern of expressio n similar to the placenta. The similarity of expression observed in fe tal liver and placenta suggests a coordinated regulation of expression of this gene in these tissues. There is a minimal amount of signal pr esent in the uterus and the expression does not appear to vary. We spe culate that selenoprotein p may play a role in the transplacental tran sport of selenium to the fetus during late pregnancy.