The switching role of i 2-adrenergic receptor signalling in cell survival or death decision of cardiomyocytes

How cell fate (survival or death) is determined and whether such determination depends on the strength of stimulation has remained unclear. In this study, we discover that the cell fate of cardiomyocytes switches from survival to death with the increase of I 2-adrenergic receptor (I 2-AR) stimulation. Mathematical simulations combined with biochemical experimentation of I 2-AR signalling pathways show that the gradual increment of isoproterenol (a non-selective I 2 1 /I 2 2 -AR agonist) induces the switching response of Bcl-2 expression from the initial increase followed by a decrease below its basal level. The ERK1/2 and ICER-mediated feed-forward loop is the hidden design principle underlying such cell fate switching characteristics. Moreover, we find that I 21-blocker treatment increases the survival effect of I 2-AR stimuli through the regulation of Bcl-2 expression leading to the resistance to cell death, providing new insight into the mechanism of therapeutic effects. Our systems analysis further suggests a novel potential therapeutic strategy for heart disease.