Figure 6.

Schematic depicting the effect of gamma-aminobutyric acid type A receptor π subunit (GABRP) on members of the Bcl-2 family in the apoptosis cascade and the role of Bcl-2 in balancing the apoptosis and differentiation process. (A) GABRP maintains the balance between pro-apoptotic Bad and anti-apoptotic Bcl-2 under normal conditions. However, the balance may be lost and biased towards the pro-apoptotic Bad pathway when GABRP is overexpressed. Thereafter, Bax is activated which causes cytochrome c release and activation of the caspase-mediated apoptosis cascade. (B) There is a differentiation-dependent pattern of Bcl-2 expression in the placenta whereby a signal balance between apoptosis and differentiation is achieved and hence, trophoblast mass is preserved during pregnancy.