Browsing by Author "Philip, Linda"

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    NF-kappa B inhibition compromises cardiac fibroblast viability under hypoxia
    (EXPERIMENTAL CELL RESEARCH, 2011)
    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-kappa B protects cardiac fibroblasts from hypoxia-induced cell death. Further, we examined the expression of the antiapoptotic clAP-2 and Bcl-2 in hypoxic cardiac fibroblasts, and their possible regulation by NF-kappa B. 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-kappa B in cardiac fibroblasts. Supershift assay indicated that the active NF-kappa B complex is a p65/p50 heterodimer. An I-kappa B-super-repressor was constructed that prevented NF-kappa B activation and compromised cell viability under hypoxic but not normoxic conditions. Similar results were obtained with Bay 11-7085, an inhibitor of NF-kappa B. Western blot analysis showed constitutive levels of Bcl-2 and hypoxic induction of clAP-2 in these cells. NF-kappa B inhibition reduced clAP-2 but not Bcl-2 levels in hypoxic cardiac fibroblasts. The results show for the first time that NF-kappa B is an important effector of survival in cardiac fibroblasts under hypoxic stress and that regulation of clAP-2 expression may contribute to its pro-survival role. (C) 2011 Elsevier Inc. All rights reserved.