434. Identification of differentially expressed proteins in ovine chorion rupture sites at preterm and term using proteomics

Abstract

Introduction: A significant number of babies are delivered preterm and many of these deliveries are due to spontaneous rupture of fetal membranes. However, the mechanisms underlying fetal membrane rupture are not well defined. The sheep has proved to be a valuable model for elucidating the physiology of birth, with many of the findings clearly relevant to human parturition. In the current study we have used the sheep model to investigate changes in protein expression in the chorion in relation to the onset of spontaneous full term labour. Methods: Proteomic analysis was used to compare the protein profiles at the chorion rupture site between mid/late gestation (136 days, n = 6) and term delivery (145days, n = 6). Proteins were solubilised and separated into soluble and insoluble fractions which were separated by 2D-electrophoresis. Relative protein expression was quantified using the PROGENESIS software and protein spots were picked and identified using Matrix Assisted Laser Desorption Ionisation-Time of Flight (MALDI-TOF) mass spectrometry. Data-mining used gene ontology (GO terms) for each protein and these were clustered into networks using DAVID bioinformatics resource (http://david.abcc.ncifcrf.gov/home.jsp). Results: A total of 150 protein spots were identified of which 60 proteins were found to differ by more than 2-fold between preterm and term samples. This group was significantly enriched for proteins from the several functional GO categories including; Oxidoreductase activity (7 proteins); negative regulation of apoptosis (4); structural molecule activity (7); protease inhibitor activity (7); Carbohydrate metabolism (10); Glucose metabolism (5); Glycolysis (5); response to stress (8) and heat shock (3). Of the differentially regulated proteins, 10 were found to be significantly upregulated at term (ANOVA P < 0.05) including isocitrate dehydrogenase, glutamate dehydrogenase 1, malate dehydrogenase 2. A further 10 proteins, including serpin peptidase inhibitor SERPINA12, serpin peptidase inhibitor SERPINH1 precursor and heat shock protein 90 kDa β were found to be downregulated.