Specific expression of PP5/TFPI2 mRNA by syncytiotrophoblasts in human placenta as revealed by in situ hybridization.
Placental protein 5 (PP5) is a placenta-derived glycoprotein with serine proteinase-inhibiting activity. To date its physiological functions have not been well elucidated. Recently, cDNA sequence analysis revealed that PP5 belongs to the Kunitz-type proteinase inhibitor family and it is identical to tissue factor pathway inhibitor-2 (TFPI-2), homologous to TFPI. Northern blot analysis demonstrated that placental tissue is extremely rich in the transcripts. This study localized PP5/TFPI-2 mRNA in placental tissues at three different gestational periods using in situ hybridization. PP5/TFPI-2 mRNA was specifically detected in syncytiotrophoblast at any gestational period examined, suggesting that syncytiotrophoblast is the principal production site of PP5/TFPI-2 in developing placental tissues. This mRNA expression pattern of PP5/TFPI-2 is quite different from that of TFPI, which is mainly found in vascular endothelial cells. The results indicated possible roles of PP5/TFPI-2 in the trophoblast differentiation and in the maintenance of intervillous blood flow. Also, Northern analysis demonstrated no or little expression of PP5/TFPI-2 in four choriocarcinoma cell lines, in contrast to its abundant expression in syncytiotrophoblast.
Udagawa
K
K
Department of Obstetrics, Yokohama City University School of Medicine, Yokohama, Japan.
Miyagi
Y
Y
Hirahara
F
F
Miyagi
E
E
Nagashima
Y
Y
Minaguchi
H
H
Misugi
K
K
Yasumitsu
H
H
Miyazaki
K
K
D000328:Adult; D015152:Blotting, Northern; D002822:Choriocarcinoma / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017403:In Situ Hybridization; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000235:genetics / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000378:metabolism
D006023:Glycoproteins; D011257:Pregnancy Proteins; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; C021240:tissue-factor-pathway inhibitor 2