Down-regulation of StarD7 by RNA interference increases beta-hCG production and secretion in JEG-3 cells

FLORES-MARTÍN, JÉSICA; RENA VIVIANA; RIDANO, MAGALÍ; PANZETTA-DUTARI GRACIELA; GENTI DE RAIMONDI SUSANA

Santiago de Chile

Congreso; IFPA meeting 2010; 2010

International Federation Placenta Associations

StarD7 is a member of the START-domain protein family whose function remains poorly defined.We have recently reported that StarD7 is partially relocated from the cytoplasm to the plasma membrane during in vitro cytotrophoblast differentiation into syncytiotrophoblast. Furthermore, we have shown that ß-catenin activates human StarD7 expression through Wnt/ß-catenin signaling. Herein, to explore its function in JEG-3 cells StarD7 expression was down-regulated by siRNA. Silencing of StarD7 expression, confirmed by qRT-PCR and western blot, led to a marked decrease of ß-catenin, Cnx43, iNOS, MBD2, ABCG2 and TGFbRII mRNA levels, all of them associated with Wnt signalling. In contrast, expression of syncytial formation markers, such as b-hCG protein production and secretion, as well as b-hCG mRNA levels, was increased by StarD7 siRNA. In addition, fluorescent microscopy performed by immunostaining for desmoplakin suggested that there was a reduction of intercellular desmosomes between adjacent JEG-3 cells after knocking-down StarD7 expression. Whether this response is unique to this cell line is being currently investigating using other models such as BeWo and primary trophoblast cells. These findings indicate that the inhibition of StarD7 transcript level alters the expression of several critical genes suggesting that it may play a role in placental development.