Placental leucine aminopeptidase/oxytocinase in maternal serum and placenta during normal pregnancy.
Placental leucine aminopeptidase (P-LAP), which is identical with cystine aminopeptidase as oxytocinase, was found to be homologous with rat insulin-regulated membrane aminopeptidase (IRAP) by sequence comparison. In the current study, we determined the P-LAP levels in maternal serum and placenta during healthy pregnancy. P-LAP activities in maternal serum increased with gestation and rose to the peak of 80 IU/ml at 38 weeks of gestation. Northern blot analysis revealed the increase of P-LAP mRNA levels in placenta in the third trimester compared to the first trimester. P-LAP protein and related activities could be detected in the conditioned medium of placental tissue, while they could not be detected in that of human umbilical vein endothelial cells. Immunohistochemically P-LAP was positively stained in the apical membrane of syncytiotrophoblast cells throughout the gestation. These results established the normal range of serum and tissue P-LAP levels during pregnancy and the possible source of serum P-LAP, which will be helpful to elucidate the physiological and clinical roles of P-LAP/oxytocinase/IRAP.
Yamahara
N
N
Department of Obstetrics and Gynecology, Nagoya University School of Medicine, Nagoya 466-8550, Japan.
Nomura
S
S
Suzuki
T
T
Itakura
A
A
Ito
M
M
Okamoto
T
T
Tsujimoto
M
M
Nakazato
H
H
Mizutani
S
S
D000328:Adult; D015152:Blotting, Northern; D015153:Blotting, Western; D003470:Culture Media; D010122:Cystinyl Aminopeptidase / Q000097:blood / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007931:Leucyl Aminopeptidase / Q000097:blood / Q000378:metabolism*; D009924:Organ Culture Techniques; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy / Q000378:metabolism*; D012016:Reference Values; D013997:Time Factors
D003470:Culture Media; D007931:Leucyl Aminopeptidase; D010122:Cystinyl Aminopeptidase