title: Labour is associated with increased expression of type-IIA secretory phospholipase A2 but not type-IV cytosolic phospholipase A2 in human myometrium.
abstract: Human labour is associated with increased prostaglandin synthesis within the uterus. The aim of this study was to examine the expression of the type-IV cytosolic phospholipase A2 (cPLA2-IV) and the type IIA secretory phospholipase A2 (sPLA2-IIA) in myometrium in association with labour onset at term and preterm deliveries. These enzymes are important for the release of the prostaglandin precursor, arachidonic acid, from phospholipid membrane stores. RT-PCR was used to determine differences in gene expression between non-labour and labour groups. Expression of sPLA2-IIA in human myometrium was significantly increased with pregnancy, and with labour, both at term and preterm. Expression of cPLA2-IV in myometrium was not significantly altered with respect to pregnancy or labour. Immunohistochemical analysis demonstrated differences in the spatial localization of cPLA2-IV and sPLA2-IIA protein in upper and lower segment myometrium. cPLA2-IV was predominantly in vascular endothelial cells, while sPLA2-IIA was observed in vascular, endothelial and smooth muscle cells. In addition, sPLA2-IIA showed a distinct nuclear or perinuclear localization in myometrial smooth muscle cells of the lower segment. We postulate that the increased expression of sPLA2-IIA rather than cPLA2-IV in the myometrium may play a role in the onset and/or maintenance of human parturition.
authors.affiliation: Biomedical Research Institute, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK. D.M.Slater@warwick.ac.uk
authors.forename: Donna M
authors.initials: DM
authors.lastname: Slater
authors.forename: Shirley
authors.initials: S
authors.lastname: Astle
authors.forename: Phillip R
authors.initials: PR
authors.lastname: Bennett
authors.forename: Steven
authors.initials: S
authors.lastname: Thornton
mesh_terms: D000328:Adult; D004730:Endothelium, Vascular / Q000737:chemistry / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D054501:Group II Phospholipases A2; D054513:Group IV Phospholipases A2; D006801:Humans; D007743:Labor, Obstetric / Q000235:genetics / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000737:chemistry / Q000378:metabolism; D009215:Myometrium / Q000737:chemistry / Q000201:enzymology*; D010741:Phospholipases A / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054513:Group IV Phospholipases A2; C516389:PLA2G4A protein, human; D054467:Phospholipases A2