title: Altered expression of human endogenous retroviruses syncytin-1, syncytin-2 and their receptors in human normal and gestational diabetic placenta.
abstract: BACKGROUND
  Syncytins belong to the Human Endogenous Retrovirus family. The syncytin-1 receptor, SLC1A5, and syncytin-2 receptor, MFSD2, interact with their respective syncytin proteins to induce syncytiotrophoblast formation. However, there is no information about syncytins in gestational diabetic placenta. Therefore, we studied the expression and localization of syncytins and their receptors during normal placental development and in gestational diabetic placenta.
  
  
  METHODS
  Immunohistochemistry and Western-blot methods were performed with antibodies against syncytin-1, syncytin-2, SLC1A5 and MFSD2 in human first trimester placental tissues, normal term and gestational diabetic placentas. Syncytin-1, syncytin-2 and MFSD2 mRNA transcripts were determined by qRT-PCR in normal and diabetic term placentas.
  
  
  RESULTS
  Cytoplasmic syncytin-1, syncytin-2, SLC1A5 and MFSD2 immunoreactions were observed in the trophoblastic layers in all placental samples. Some of the stromal cells showed strong cytoplasmic punctate staining. There were significantly weak syncytin-2 and MFSD2 immunoreaction intensities in diabetic placentas by ImageJ analysis, in parallel with decreased syncytin-2 and MFSD2 proteins in diabetic placentas by Western-blot. Protein expression of SLC1A5 increased dramatically in early pregnancy compared to term placenta. Syncytin-1, syncytin-2 and MFSD2 mRNA transcripts showed similar relative expression pattern by qRT-PCR.
  
  
  CONCLUSIONS
  Syncytins were localized not only in cytotrophoblast cells and the basement membrane of the syncytiotrophoblast but also in the apical microvillous membrane and cytoplasm of syncytiotrophoblast, and some of the stromal cells and endothelium. Decreased syncytin-2 and MFSD2 proteins in gestational diabetic placentas might cause abnormal syncytiotrophoblast formation and possibly be involved in the pathology. Therefore, our study highlights an important potential relationship between syncytins and gestational diabetic placenta.
authors.affiliation: Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya, Turkey.
authors.forename: Bikem
authors.initials: B
authors.lastname: Soygur
authors.affiliation: Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya, Turkey. leylasati@yahoo.com.
authors.forename: Leyla
authors.initials: L
authors.lastname: Sati
authors.affiliation: Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya, Turkey.
authors.forename: Ramazan
authors.initials: R
authors.lastname: Demir
mesh_terms: D000328:Adult; D026962:Amino Acid Transport System ASC / Q000096:biosynthesis*; D015153:Blotting, Western; D020077:Endogenous Retroviruses; D005260:Female; D015686:Gene Products, env / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D015778:Minor Histocompatibility Antigens / Q000096:biosynthesis*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000096:biosynthesis*; D011254:Pregnancy in Diabetics / Q000378:metabolism / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D026962:Amino Acid Transport System ASC; C518353:ERVFRD-1 protein, human; D015686:Gene Products, env; D015778:Minor Histocompatibility Antigens; D011257:Pregnancy Proteins; C420506:SLC1A5 protein, human; C405335:syncytin