The uterus is a highly complex organ which facilitates the initial contact between maternal and foetal tissue in the establishment of pregnancy. The uterine epithelial cells (UEC) are only receptive to implantation for a short time and to achieve this they undergo a series of changes known as the plasma membrane transformation. One aspect of this transformation is the loss of focal adhesions on the basal plasma membrane to allow removal of UECs at the time of implantation. Apoptosis has also been documented in UECs surrounding the implantation chamber.
Alpha-parvin is a paxillin and f-actin binding protein, found primarily in focal adhesion complexes. Its phosphorylation has been shown to play a role in focal adhesion disassembly during mitotic entry but it has not been investigated in the uterus. The aim of this study is to explore the role alpha-parvin plays in focal adhesion disassembly within the uterus during early pregnancy.
In vivo results indicate that alpha-parvin is present on day 1 of early pregnancy and absent during implantation similar to other focal adhesion-associated proteins. It is not basally located, but is cytoplasmically dispersed, suggesting a role in cell cycle regulation. Phosphorylated alpha-parvin was absent on day 1, but present at the time of implantation. Phosphorylated alpha-parvin was also found to be significantly increased in ECC cells just prior to the entry to mitosis and was shown to be phosphorylated by cyclin B1/cdc2. The appearance of cytoplasmic alpha-parvin and phosphorylated alpha-parvin at the time of implantation, as well as the significant increase in vitro upon entry to mitosis, suggests a role for these proteins in regulation of the cell cycle. This suggests a role in apoptosis via focal adhesion disassembly during implantation.