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Increase in epidermal growth factor receptor and its mRNA levels by parathyroid hormone (1‐34) and parathyroid hormone‐related protein (1‐34) during differentiation of human trophoblast cells in culture
Author(s) -
Alsat Eliane,
Haziza Jocelyne,
Scippo MarieLouise,
Frankenne Francis,
EvainBrion Danièle
Publication year - 1993
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240530105
Subject(s) - autophosphorylation , syncytiotrophoblasts , parathyroid hormone , endocrinology , medicine , epidermal growth factor , parathyroid hormone related protein , protein kinase a , protein kinase c , receptor , chemistry , cell culture , biology , kinase , microbiology and biotechnology , placenta , calcium , pregnancy , fetus , genetics
Human cytotrophoblasts in culture aggregate and fuse to form syncytiotrophoblasts. This process is associated with an increase in epidermal growth factor receptor (EGFR) expression [Alsat et al.: J Cell Physiol 154:122–128, 1993]. Recent studies have demonstrated the presence of parathyroid hormone‐related protein (PTHrP) in the human uterus and placenta. This led us to study the effect of PTH (1–34) and PTHrP (1–34) on the expression of EGFR during this differentiation process. Both peptides induced a concentration‐dependent increase in EGF binding, with a maximal effect at the physiological concentration of 1 nM. EGFR protein level assessed by cross‐linking and immunoblotting and EGFR biological activity assessed by measuring its EGF‐induced autophosphorylation were increased 2‐ and 2.5‐fold, respectively, when cells were treated for 24 h with 0.1 μM PTHrP or PTH compared to control cells. This effect was time‐dependent with a maximum at 3 h of treatment. This treatment also increased trophoblast cell EGFR mRNA levels, suggesting transcriptional regulation of the EGFR. To ascertain whether activation of protein kinase C (PKC) or protein kinase A (PKA) is involved in this PTH effect, we determined EGFR protein level and EGFR autophosphorylation after exposure of cells to PKA inhibitor and PKC inhibitor, alone or together with the peptide. The presence of a PKC inhibitor blocked a further increase in EGFR number by PTH, while PKA inhibitor had no effect. These results show that PTH and PTHrP increase the synthesis of EGF receptors which are strongly expressed in syncytiotrophoblasts and suggested that these peptides might be involved in human placental development.