Abstract |
Cardiac fibroblasts are reported to be relatively resistant to stress stimuli compared to cardiac myocytes and fibroblasts of non-cardiac origin. However, the mechanisms that facilitate their survival under conditions of stress remain unclear. We explored the possibility that NF-κB protects cardiac fibroblasts from hypoxia-induced cell death. Further, we examined the expression of the antiapoptotic cIAP-2 and Bcl-2 in hypoxic cardiac fibroblasts, and their possible regulation by NF-κB. Phase contrast microscopy and propidium iodide staining revealed that cardiac fibroblasts are more resistant than pulmonary fibroblasts to hypoxia. Electrophoretic Mobility Shift Assay showed that hypoxia activates NF-κB in cardiac fibroblasts. Supershift assay indicated that the active NF-κB complex is a p65/p50 heterodimer. An I-κB-super-repressor was constructed that prevented NF-κB activation and compromised cell viability under hypoxic but not normoxic conditions. Similar results were obtained with Bay 11-7085, an inhibitor of NF-κB. Western blot analysis showed constitutive levels of Bcl-2 and hypoxic induction of cIAP-2 in these cells. NF-κB inhibition reduced cIAP-2 but not Bcl-2 levels in hypoxic cardiac fibroblasts. The results show for the first time that NF-κB is an important effector of survival in cardiac fibroblasts under hypoxic stress and that regulation of cIAP-2 expression may contribute to its pro-survival role.
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Authors | M Sangeetha, Malini S Pillai, Linda Philip, Edward G Lakatta, K Shivakumar |
Journal | Experimental cell research
(Exp Cell Res)
Vol. 317
Issue 7
Pg. 899-909
(Apr 15 2011)
ISSN: 1090-2422 [Electronic] United States |
PMID | 21211536
(Publication Type: Journal Article, Research Support, N.I.H., Intramural, Research Support, Non-U.S. Gov't)
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Copyright | Copyright © 2010 Elsevier Inc. All rights reserved. |
Chemical References |
- BAY 11-7085
- Inhibitor of Apoptosis Proteins
- NF-kappa B
- Nitriles
- Proto-Oncogene Proteins c-bcl-2
- Sulfones
- Caspase 3
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Topics |
- Animals
- Caspase 3
(metabolism)
- Cell Survival
(physiology)
- Fibroblasts
(cytology, drug effects, physiology)
- Hypoxia
(metabolism)
- Inhibitor of Apoptosis Proteins
(genetics, metabolism)
- Male
- Myocytes, Cardiac
(cytology, drug effects, physiology)
- NF-kappa B
(antagonists & inhibitors)
- Nitriles
(pharmacology)
- Proto-Oncogene Proteins c-bcl-2
(genetics, metabolism)
- Rats
- Rats, Sprague-Dawley
- Sulfones
(pharmacology)
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