Decrease in annexin I messenger ribonucleic acid expression in human amnion with labor.
OBJECTIVE
Annexins are a superfamily of proteins that are thought to inhibit phospholipase A2 activity and hence inhibit prostaglandin production. The purpose of this study was to test the hypothesis that annexin I concentration in human amnion is reduced with labor and that this reduction is mediated by a decrease in annexin I messenger ribonucleic acid expression.


METHODS
Amnion and choriodecidua were collected from term singleton pregnancies, eight after spontaneous vaginal delivery and eight from elective cesarean section without labor. Annexin I protein was quantitated by Western blotting. Ribonucleic acid was isolated from amnion, and then annexin I messenger ribonucleic acid was identified by Northern hybridization and quantitated by slot blotting.


RESULTS
Annexin I (35 kd) was identified in amnion tissue. The concentration in the group undergoing labor (320 +/- 45 integrated optical density units, mean +/- SE) was significantly reduced (p < 0.05) compared with that in the group not undergoing labor (635 +/- 65 units). The size of the annexin I messenger ribonucleic acid was approximately 1.8 kb. The mean integrated optical density for the labor group (840 +/- 139 units, mean +/- SE) was significantly reduced (p < 0.05) compared with that of the nonlabor group (1912 +/- 464 units).


CONCLUSIONS
There is a significant decrease in annexin I messenger ribonucleic acid expression in human amnion with labor, corresponding to a significant decrease in annexin I protein concentration. This may contribute to the increased phospholipase A2 activity, arachidonic acid mobilization, and prostaglandin production at labor in humans.
Lynch-Salamon
D I
DI
Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, OH 45267-0526.
Everson
W V
WV
Myatt
L
L
D000650:Amnion / Q000378:metabolism*; D017305:Annexin A1 / Q000235:genetics* / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism*
D017305:Annexin A1; D012333:RNA, Messenger