In:
Circulation Research, Ovid Technologies (Wolters Kluwer Health), Vol. 92, No. 7 ( 2003-04-18), p. 715-724
Abstract:
We tested the hypothesis that myocyte loss in failing human hearts occurs by different mechanisms: apoptosis, oncosis, and autophagic cell death. Explanted hearts from 19 patients with idiopathic dilated cardiomyopathy (EF≤20%) and 7 control hearts were analyzed. Myocyte apoptosis revealed by caspase-3 activation and TUNEL staining occurred at a rate of 0.002±0.0005% ( P 〈 0.05 versus control) and oncosis assessed by complement 9 labeling at 0.06±0.001% ( P 〈 0.05). Cellular degeneration including appearance of ubiquitin containing autophagic vacuoles and nuclear disintegration was present at the ultrastructural level. Nuclear and cytosolic ubiquitin/protein accumulations occurred at 0.08±0.004% ( P 〈 0.05). The ubiquitin-activating enzyme E1 and the ligase E3 were not different from control. In contrast, ubiquitin mRNA levels were 1.8-fold ( P 〈 0.02) elevated, and the conjugating enzyme E2 was 2.3-fold upregulated ( P 〈 0.005). The most important finding, however, is the 2.3-fold downregulation of the deubiquitination enzyme isopeptidase-T and the 1.5-fold reduction of the ubiquitin-fusion degradation system-1, which in conjunction with unchanged proteasomal subunit levels and proteasomal activity results in massive storage of ubiquitin/protein complexes and in autophagic cell death. A 2-fold decrease of cathepsin D might be an additional factor responsible for the accumulation of ubiquitin/protein conjugates. It is concluded that in human failing hearts apoptosis, oncosis, and autophagy act in parallel to varying degrees. A disturbed balance between a high rate of ubiquitination and inadequate degradation of ubiquitin/protein conjugates may contribute to autophagic cell death. Together, these different types of cell death play a significant role for myocyte disappearance and the development of contractile dysfunction in failing hearts.
Type of Medium:
Online Resource
ISSN:
0009-7330
,
1524-4571
DOI:
10.1161/01.RES.0000067471.95890.5C
Language:
English
Publisher:
Ovid Technologies (Wolters Kluwer Health)
Publication Date:
2003
detail.hit.zdb_id:
1467838-X
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