Regulation of Protein Expression and Function of OCTN2 in Forskolin-Induced Syncytialization in BeWo Cells
Journal
Placenta
Journal Volume
30
Journal Issue
2
Pages
187
Date Issued
2009-02
Author(s)
Abstract
Placental OCTN2 is a high-affinity carnitine transporter that can interact with a number of therapeutic agents. The process of syncytialization is associated with the expression of a variety of genes. However, the association between syncytialization and OCTN2 expression is not yet clear. Given that forskolin induces BeWo cells to undergo biochemical and morphological differentiation, the purpose of the present study was to investigate whether the function and expression of OCTN2 are influenced by forskolin treatment during syncytialization. The forskolin-induced differentiation of BeWo cells was validated by secretion of β-human chorionic gonadotropin (β-hCG) and syncytin expression. Cellular localization of OCTN2 was analyzed by confocal microscopy. Expression of OCTN2 and the modular proteins PDZK1, PDZK2, NHERF1 and NHERF2 was analyzed by Western blotting and carnitine uptake by BeWo cells was estimated and the kinetic properties of uptake measured. The results showed that forskolin treatment increased β-hCG secretion and syncytin expression, suggesting induction of syncytialization. Confocal images of BeWo cells showed the localization of OCTN2 in the brush-border membrane. OCTN2 protein expression was upregulated in isolated brush-border membranes by long-term forskolin treatment, but the Vm for carnitine uptake was unchanged, although the Km increased. PDZK1, NHERF1 and NHERF2 protein expression in the brush-border membrane was downregulated by forskolin treatment, whereas PDZK2 levels remained unchanged. In conclusion, protein expression and function of OCTN2 in BeWo cells can be regulated by forskolin treatment. While the presence of forskolin results in an increase in OCTN2 protein expression, the increase in uptake capacity may be compensated by the decreased expression of PDZK1, NHERF1 or NHERF2. ? 2008 Elsevier Ltd. All rights reserved.
Subjects
BeWo cells; Carnitine; NHERF; OCTN2; PDZK; Syncytialization
SDGs
Other Subjects
carnitine; chorionic gonadotropin beta subunit; forskolin; nherf1 protein; NHERF2 protein; OCTN2 protein; PDZ protein; placenta protein; unclassified drug; article; brush border; cancer cell culture; cell transport; confocal microscopy; controlled study; human; human cell; immunocytochemistry; placenta; priority journal; protein expression; syncytiotrophoblast; Western blotting; Carrier Proteins; Cell Line, Tumor; Cell Transformation, Neoplastic; Choriocarcinoma; Chorionic Gonadotropin, beta Subunit, Human; Forskolin; Gene Expression Regulation; Gene Products, env; Giant Cells; Humans; Microvilli; Organic Cation Transport Proteins; Phosphoproteins; Pregnancy Proteins; Sodium-Hydrogen Antiporter; Trophoblasts
Type
journal article