Growth factors interaction with transcriptional regulators

Another way to regulate caspases is by interaction with inhibitors. For example, fibroblasts that overexpress the growth-promoting transcription factor c-Myc die, because the caspase inhibitors (lAPs), inhibitors of apoptosis, are inactivated by phosphorylation. In Fig. 13.6 is shown how phosphorylation of a caspase inhibitor controls caspase activity and apoptosis. When cells are driven to proliferate by an overactive transcriptional activator, such as c-Myc, an unregulated active caspase, no longer restrained by the inhibitor, can overcome the effect of Bcl-2 and the cell will eventually die. Only when Bcl-2 is over-et ressed simultaneously with c-Myc, can cell death be prevented. Thus, Bcl-2 keeps the c-Myc signals in check.22,23... 

Cardiomyogenic differentiation of ESCs is regulated by certain soluble factors and signaling molecules interacting with cardiac-specific transcription factors. BMP-2 plays a central role in the induction of cardiac formation in vertebrate embryos, and expression of BMP-2 is mediated by GATA-4 and Nkx-2.5 [150]. It is also been reported that GATA-4 and Nkx-2.5 are essential for cardiac development. Other growth factors and soluble chemicals, such as FGF, IGF-1, and dimethyl sulfoxide, have also been proven to be involved in heart formation of vertebrates... 

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