Showing papers by "Nanette H. Bishopric published in 1996"

Expression of Inducible Nitric Oxide Synthase in Human Heart Failure

Abstract: Background There is increasing evidence that alterations in nitric oxide synthesis are of pathophysiological importance in heart failure. A number of studies have shown altered nitric oxide production by the endothelial constitutive isoform of nitric oxide synthase (NOS), but there is very little information on the role of the inducible isoform. Methods and Results We analyzed inducible NOS (iNOS) expression in ventricular myocardium taken from 11 control subjects (who had died suddenly from noncardiac causes), from 10 donor hearts before implantation, and from 51 patients with heart failure (24 with dilated cardiomyopathy [DCM], 17 with ischemic heart disease [IHD], and 10 with valvular heart disease [VHD]). Reverse transcription–polymerase chain reaction was used to confirm the presence of intact mRNA and to detect expression of iNOS and atrial natriuretic peptide (ANP). ANP was used as a molecular phenotypic marker of ventricular failure. iNOS was expressed in 36 of 51 biopsies (71%) from patients with...

Physical and functional sensitivity of zinc finger transcription factors to redox change.

Abstract: Redox regulation of DNA-binding proteins through the reversible oxidation of key cysteine sulfhydryl groups has been demonstrated to occur in vitro for a range of transcription factors. The direct redox regulation of DNA binding has not been described in vivo, possibly because most protein thiol groups are strongly buffered against oxidation by the highly reduced intracellular environment mediated by glutathione, thioredoxin, and associated pathways. For this reason, only accessible protein thiol groups with high thiol-disulfide oxidation potentials are likely to be responsive to intracellular redox changes. In this article, we demonstrate that zinc finger DNA-binding proteins, in particular members of the Sp-1 family, appear to contain such redox-sensitive -SH groups. These proteins displayed a higher sensitivity to redox regulation than other redox-responsive factors both in vitro and in vivo. This effect was reflected in the hyperoxidative repression of transcription from promoters with essential Sp-1 binding sites, including the simian virus 40 early region, glycolytic enzyme, and dihydrofolate reductase genes. Promoter analyses implicated the Sp-1 sites in this repression. Non-Sp-1-dependent redox-regulated genes including metallothionein and heme oxygenase were induced by the same hyperoxic stress. The studies demonstrate that cellular redox changes can directly regulate gene expression in vivo by determining the level of occupancy of strategically positioned GC-binding sites.