Dehydroepiandrosterone sulfate-binding sites in plasma membrane from human uterine cervical fibroblasts.
Dehydroepiandrosterone sulfate (DHA-S) plays a critical role in cervical dilatation at labor. Incubation of cervical fibroblasts with [3H]DHA-S caused a rapid and saturable increase in cellular radioactivity: an apparent equilibrium was reached by 2 min. There was no detectable conversion of DHA-S into DHA or oestradiol. When the fibroblasts loaded with [3H]DHA-S were homogenized and fractionated, the specific radioactivity in the plasma membrane fraction was enriched approximately 8- to 9-fold compared with the whole homogenate; only low amounts of radioactivity were observed in the other subcellular fractions. The binding of DHA-S to plasma membrane preparations showed saturation kinetics with an apparent equilibrium dissociation constant (Kd) of 12 nM, and the binding capacity (Bmax) was calculated to be 1.25 fmol/mg protein. Neither DHA nor oestrone sulfate affected [3H]DHA-S binding to the plasma membrane. The plasma membranes of skin fibroblasts did not show specific binding sites for DHA-S. These findings demonstrate the presence of specific binding sites for DHA-S in the plasma membrane of cervical stroma cells. The fetal adrenal steroid may exert its action on cervical ripening at least in part through membrane-associated binding sites, or receptors.
Imai
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Department of Obstetrics and Gynecology, Gifu University School of Medicine, Japan.
Ohno
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T
Tamaya
T
T
D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002584:Cervix Uteri / Q000378:metabolism*; D002585:Cesarean Section; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007044:Hysterectomy; D007700:Kinetics; D012867:Skin / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate