596: Determinants of invasion in human trophoblast cells

The morphological and functional differentiation of human trophoblast cells ends with the formation of terminally differentiated multinucleated syncytial trophoblasts. This in vivo differentiation is mimicked in vitro during the primary culture of extravillous cytotrophoblasts: isolated mononuclear cytotrophoblasts aggregate and fuse to form syncytia. This in vitro differentiation is associated with an increase in epidermal growth factor receptor (EGF-R) expression and a transitory increase in E-cadherin expression during cell aggregation. In the present study, we investigated the expression of pp60c-src during morphological differentiation of trophoblast cells. Cultures were terminated at various time intervals and pp60c-src was analysed by immunocytochemistry using a specific antibody. In addition, pp60c-src was investigated by western blot analysis and its tyrosine kinase activity was measured concomitantly. In mononuclear cytotrophoblasts, pp60c-src was localized at cell-matrix contacts and during the aggregation of cytotrophoblasts, pp60c-src was distributed on the cell surface at points of cell-cell contact being colocalized with EGF-R and E-cadherin. The kinase activity of the pp60c-src protein increased significantly at day 2 when cells were completely aggregated and started to fuse, and remained elevated while cells underwent further differentiation. Inhibition of pp60c-src by herbimycin A at 0.25 to 1 microgram/ml during the first day of culture was associated with a decreased expression of tyrosine kinase activity of EGF-R and an increase in E-cadherin expression. These data suggest that pp60c-src is involved in the modulation of trophoblast cell aggregation and fusion leading to syncytial formation.

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Pre-β-HDL stimulates placental lactogen release from human trophoblast cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.276.2.e384 ◽

1999 ◽

Vol 276 (2) ◽

pp. E384-E389

Author(s):

Stuart Handwerger ◽

Geeta Datta ◽

Brian Richardson ◽

Carrie M. Schmidt ◽

Tariq Siddiqi ◽

...

Keyword(s):

Density Lipoprotein ◽

Placental Lactogen ◽

Trophoblast Cells ◽

Term Pregnancy ◽

Human Trophoblast ◽

Maximal Stimulation ◽

Dose Dependent Increase ◽

Dose Dependent ◽

Dimensional Electrophoresis ◽

Human Trophoblast Cells

To examine whether pre-β-high-density lipoprotein (HDL) may be involved in regulation of human placental lactogen (hPL) release, pre-β-HDL was isolated from term pregnancy serum, and the effect of purified pre-β-HDL on hPL release from trophoblast cells was examined after 1 h of exposure. Pre-β-HDL stimulated a dose-dependent increase in hPL release with half-maximal stimulation at a dose of 300–400 μg/ml, which is within the normal physiological range during pregnancy. Analysis of pre-β-HDL and α-HDL in serum from pregnant women at different stages of gestation (determined by Western blot analysis) indicated that the pre-β-HDL-to-α-HDL ratio increased linearly after the 10th week of gestation ( r = 0.88, P < 0.001), reaching a maximum sixfold greater than that of nonpregnant women. The increase in serum pre-β-HDL during pregnancy paralleled that of plasma hPL concentrations ( r = 0.93, P < 0.001). Two-dimensional electrophoresis indicated that the increase in pre-β-HDL was due primarily to an increase in pre-β1-HDL and pre-β2-HDL, two of the three forms of pre-β-HDL present in blood. These results suggest a role for pre-β-HDL in the regulation of hPL expression during pregnancy.

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