title: Collagen type IV at the fetal-maternal interface.
abstract: BACKGROUND
  Extracellular matrix proteins play a crucial role in influencing the invasion of trophoblast cells. However the role of collagens and collagen type IV (col-IV) in particular at the implantation site is not clear.
  
  
  METHODS
  Immunohistochemistry was used to determine the distribution of collagen types I, III, IV and VI in endometrium and decidua during the menstrual cycle and the first trimester of pregnancy. Expression of col-IV alpha chains during the reproductive cycle was determined by qPCR and protein localisation by immunohistochemistry. The structure of col-IV in placenta was examined using transmission electron microscopy. Finally, the expression of col-IV alpha chain NC1 domains and collagen receptors was localised by immunohistochemistry.
  
  
  RESULTS
  Col-IV alpha chains were selectively up-regulated during the menstrual cycle and decidualisation. Primary extravillous trophoblast cells express collagen receptors and secrete col-IV in vitro and in vivo, resulting in the increased levels found in decidua basalis compared to decidua parietalis. A novel expression pattern of col-IV in the mesenchyme of placental villi, as a three-dimensional network, was found. NC1 domains of col-IV alpha chains are known to regulate tumour cell migration and the selective expression of these domains in decidua basalis compared to decidua parietalis was determined.
  
  
  CONCLUSIONS
  Col-IV is expressed as novel forms in the placenta. These findings suggest that col-IV not only represents a structural protein providing tissue integrity but also influences the invasive behaviour of trophoblast cells at the implantation site.
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom. Electronic address: cmo35@cam.ac.uk.
authors.forename: C M
authors.initials: CM
authors.lastname: Oefner
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Sharkey
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
authors.forename: L
authors.initials: L
authors.lastname: Gardner
authors.affiliation: MRC Centre for Reproductive Health, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Critchley
authors.affiliation: Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Oyen
authors.affiliation: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Moffett
mesh_terms: D002824:Chorionic Villi / Q000378:metabolism; D024141:Collagen Type IV / Q000378:metabolism*; D003656:Decidua / Q000378:metabolism*; D010064:Embryo Implantation / Q000502:physiology; D005260:Female; D006801:Humans; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism; D014327:Trophoblasts / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D024141:Collagen Type IV
keywords: Alpha(IV) NC1 domains; Extracellular matrix; Placental bed; Reproductive cycle; Trophoblast