Increased expression of ac-FoxO1 protein in prelabor fetal membranes overlying the cervix: possible role in human fetal membrane rupture.

Forkhead box O proteins have critical roles in a number of cellular processes, including apoptosis. Acetylation and phosphorylation of forkhead box O proteins are posttranslational modifications that attenuate their transcriptional activity. As supracervical fetal membranes are characterized by increased cell death, the aim of this study was to compare the expression of forkhead box O1, acetylated-forkhead box O1, and Ser-256 phosphorylated forkhead box O1 at supracervical and distal site fetal membrane. Fetal membranes overlying the cervix were identified in situ in women undergoing term elective Caesarean section. Immunohistochemistry (n = 7) was used to analyze the protein expression of forkhead box O1, acetylated-forkhead box O1, and Ser-256 phosphorylated forkhead box O1. There was no difference in forkhead box O1 and Ser-256 phosphorylated forkhead box O1 protein expression between the 2 sites. However, when compared with distal site, the intensity and extent of staining of acetylated-forkhead box O1 were greater in amnion and chorion obtained from the supracervical site. In summary, supracervical fetal membranes are characterized by increased acetylated-forkhead box O1 protein expression. Although the precise role and contribution of acetylated-forkhead box O1 in the process of human fetal membrane rupture are unknown, it has been implicated in apoptosis and/or cell cycle regulation.