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IGF binding protein-1 (IGFBP-1) is preferentially associated with the fetal facing basal surface of the syncytiotrophoblast in the human placenta
被引:5
作者:
Fang, JG
Furesz, TC
Smith, CH
Fant, ME
机构:
[1] Univ Texas, Sch Med, Div Neonatal Perinatal Med, Houston, TX 77030 USA
[2] Washington Univ, Sch Med, Dept Pediat, St Louis, MO USA
关键词:
placenta;
IGFBP-1;
insulin-like growth factors;
IGF binding proteins;
D O I:
10.1054/ghir.1999.0127
中图分类号:
Q2 [细胞生物学];
学科分类号:
071009 ;
090102 ;
摘要:
IGF receptors are expressed in a spatially polarized manner on the syncytiotrophoblast cell membrane. We therefore examined the hypothesis that IGFBPs expressed at the maternal-fetal interface interact with distinct surfaces of the syncytiotrophoblast membrane to modulate IGF function. Membrane vesicles were prepared specifically from the maternal-facing, microvillous membrane (MVM) and the fetal-facing, basal membrane (BM) surfaces of the syncytiotrophoblast. The association of IGFBPs with each membrane preparation was determined by ligand blot analysis. A doublet migrating at 38/42 kD was detected in both MVM and BM preparations. Selective immunoprecipitation followed by ligand blot analysis identified this IGF binding species as IGFBP-3. Additionally, a protein migrating at approximately 29 kD was associated primarily with the BM. This protein was identified as IGFBP-1 by both immunoprecipitation and ligandblotting techniques. Non-denaturing PAGE revealed five distinct bands corresponding to different degrees of phosphorylation, The phosphorylation pattern of BM-associated IGFBP-1 was identical to that of native IGFBP-1 in amniotic fluid. Immunohistological analysis of term placenta revealed IGFBP-1-specific staining of the syncytiotrophoblast and the fetal capillary/pericapillary bed. The localization of IGFBP-1 to a distinct compartment within the fetal placenta, not in proximity to the syncytiotrophoblast type I IGF receptor, suggests it may play a role in regulating/targeting IGF activity within the stromal compartment or by exerting IGF-independent effects on the basal surface of the syncytiotrophoblast. The nature of its binding to the BM has not been determined. (C) 1999 Harcourt Publishers Ltd.
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页码:438 / 444
页数:7
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