Role of mTOR signalling in BeWo trophoblast differentiation and fusion

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 498-514-Female Reproductive Endocrinology
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-505
Isma Alkawafi*1, Manu Vatish2 and Dimitris Grammatopoulos3
1warwick medical school, coventry, 2University of Warwick, Coventry, United Kingdom, 3Univ of Warwick Biomed Res Inst, Coventry, United Kingdom
In humans, trophoblast fusion and differentiation into a multinucleate syncytium is key in the establishment of successful pregnancy. This process involves up-regulation of the fusogenic gene machinery to promote cell fusion and increased capacity for placental hormonogenesis, and is achieved by coordinated action of signalling molecules, such as cAMP and mitogen activated protein kinases (MAPKs). The mammalian target of rapamycin (mTOR), which acts as a placental growth signalling sensor, has been implicated in the pathophysiology of diseases such as IUGR, associated with abnormal trophoblast differentiation (1). mTOR is a an evolutionarily conserved member of the phosphatidylinositol-3-OH (PI-3)-kinase-related kinase (PIKKs) and its upstream activators PI3K and Akt appear to be involved in the control of trophoblast fusion (2). To investigate the role of mTOR in the trophoblast differentiation mechanisms, we used the BeWo choriocarcinoma cell line, a model of cAMP-dependent trophoblast differentiation. Cells were syncytialized with forskolin treatment for 24h. This resulted in (a) increased expression of fusogenic genes such as syncytin 1 and 2; (b) increased secretion of human chorionic gonadotropin (hCG), a hormonal marker of syncytialization as well as increased secretion of the placental hormones b2-estradiol and progesterone; and (c) increased expression of molecules important for placental endocrine function such as 11b-HSD2. In the presence of rapamysin, forskolin-induced hCG release was markedly reduced, whereas syncytin-1 and -2 mRNA expression was substantially augmented by 4 x and 2x respectively. Moreover, rapamysin abolished forskolin induction of 11b-HSD2 mRNA expression. This suggests diverse and distinct actions of mTOR on the biochemical and morphological differentiation of BeWo trophoblasts: a positive action on the endocrine phenotype coupled with a negative effect on the fusogenic capacity. These findings led us to investigate the effect of forskolin-driven adenylyl cyclase activation and intracellular cAMP production on mTOR expression and activity. Results demonstrated that within 10min of forskolin treatment there was a substantial reduction in basal mTOR phosphorylation at Ser2481 and Ser22441, which is required for mTOR activity. Moreover, forskolin treatment for 24h significantly reduced mTOR mRNA and protein expression. These results suggest novel distinct roles for mTOR in the control of trophoblast differentiation.

(1) Yung HW, et al 2012; J Pathol.   doi: 10.1002/path.4068, in press; (2) Vatish M, et al. 2012 PLoS One. 7:e29353

Nothing to Disclose: IA, MV, DG

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