[HTML][HTML] TNF provokes cardiomyocyte apoptosis and cardiac remodeling through activation of multiple cell death pathways

SB Haudek, GE Taffet, MD Schneider… - The Journal of clinical …, 2007 - Am Soc Clin Investig
SB Haudek, GE Taffet, MD Schneider, DL Mann
The Journal of clinical investigation, 2007Am Soc Clin Investig
Transgenic mice with cardiac-restricted overexpression of secretable TNF (MHCsTNF)
develop progressive LV wall thinning and dilation accompanied by an increase in
cardiomyocyte apoptosis and a progressive loss of cytoprotective Bcl-2. To test whether
cardiac-restricted overexpression of Bcl-2 would prevent adverse cardiac remodeling, we
crossed MHCsTNF mice with transgenic mice harboring cardiac-restricted overexpression of
Bcl-2. Sustained TNF signaling resulted in activation of the intrinsic cell death pathway …
Transgenic mice with cardiac-restricted overexpression of secretable TNF (MHCsTNF) develop progressive LV wall thinning and dilation accompanied by an increase in cardiomyocyte apoptosis and a progressive loss of cytoprotective Bcl-2. To test whether cardiac-restricted overexpression of Bcl-2 would prevent adverse cardiac remodeling, we crossed MHCsTNF mice with transgenic mice harboring cardiac-restricted overexpression of Bcl-2. Sustained TNF signaling resulted in activation of the intrinsic cell death pathway, leading to increased cytosolic levels of cytochrome c, Smac/Diablo and Omi/HtrA2, and activation of caspases -3 and -9. Cardiac-restricted overexpression of Bcl-2 blunted activation of the intrinsic pathway and prevented LV wall thinning; however, Bcl-2 only partially attenuated cardiomyocyte apoptosis. Subsequent studies showed that c-FLIP was degraded, that caspase-8 was activated, and that Bid was cleaved to t-Bid, suggesting that the extrinsic pathway was activated concurrently in MHCsTNF hearts. As expected, cardiac Bcl-2 overexpression had no effect on extrinsic signaling. Thus, our results suggest that sustained inflammation leads to activation of multiple cell death pathways that contribute to progressive cardiomyocyte apoptosis; hence the extent of such programmed myocyte cell death is a critical determinant of adverse cardiac remodeling.
The Journal of Clinical Investigation