Apoptotic cell death Extent affects risk factor for heart failure

Adverse cardiac remodeling occurs in mice engineered to have sustained inflammation in the heart (MHCsTNF mice) and is accompanied by increased death of the muscle cells of the heart (cardiomyocytes) by a process known as apoptosis and decreased cardiomyocyte expression of the anti-apoptotic protein Bcl-2.

In a study that appears online on August 9 in advance of publication in the September print issue of the Journal of Clinical Investigation, Douglas Mann and colleagues from Baylor College of Medicine, Houston, do not observe adverse cardiac remodeling in MHCsTNF mice engineered to constitutively express Bcl-2 in their cardiomyocytes. However, although cardiomyocyte apoptosis was decreased, it was not completely eliminated. Further analysis revealed that Bcl-2 inhibited only one pathway of apoptosis activated by the sustained inflammatory response — the intrinsic apoptotic pathway of cell death. The extrinsic apoptotic pathway of cell death proceeded unchecked. These data led the authors to suggest that the extent of cardiomyocyte apoptosis is a critical factor in determining whether or not adverse cardiac remodeling occurs.-Journal of Clinical Investigation