The present study demonstrates that prolonged exposure to high glucose increases eNOS gene expression, protein expression, and NO release. However, upregulation of eNOS and NO release is associated with a marked concomitant increase of O2- production. These results provide the molecular basis for understanding how chronic exposure to elevated glucose leads to an imbalance between NO and O2-. This may explain impaired endothelial function and be important for diabetic vascular disease.

No abstract

The transcription factor NFB plays a role in cell survival. Apoptosis, programmed cell death, via numerous triggers including death receptor ligand binding is antagonized by NFB activation and potentiated by its inhibition. In the present study, we found that caffeic acid phenethyl ester (CAPE), known to inhibit NFB, induced apoptosis via Fas signal activation in human breast cancer MCF-7 cells. CAPE activated Fas by a Fas ligand (Fas-L)-independent mechanism, induced p53-regulated Bax protein, and activated caspases. CAPE also activated MAPK family proteins p38 and JNK. SB203580, a specific inhibitor of p38 MAPK, partially suppressed CAPE-induced p53 activation, Bax expression, and apoptosis, consistent with a mechanism by which CAPE leads to Bax activation, known to be regulated by p38 and p53. The expression of dominant negative c-Jun, which inhibits the JNK signal, also suppresses CAPE-induced apoptosis, suggesting MAPKs are involved in CAPE-induced apoptosis. The expression of Fas antisense oligomers significantly suppressed the CAPE-induced activations of JNK and p38 and apoptosis as compared with Fas sense oligomers. To ascertain whether these phenomena are attributable to the inhibition of NFB by CAPE, we examined the effect of a truncated form of IB␣ (IB⌬N) lacking the phosphorylation sites essential for NFB activation. IB⌬N expression not only inhibited NFB activity but also induced Fas activation, Bax expression, and apoptosis. Our findings demonstrate that NFB inhibition is sufficient to induce apoptosis and that Fas activation plays a role in NFB inhibition-induced apoptosis in MCF-7 cells.Programmed cell death can occur in all cells by highly efficient mechanisms, leading to the quiet disposal of millions of cells in the adult human. This efficient removal of unnecessary cells is regulated not only by cell death signals but also by those of cell survival. Any imbalance between these signals can be lethal in the development of higher organisms and likely plays a major role in pathophysiological processes as diverse as atherosclerosis, heart failure, and inflammation.Originally defined as a nuclear factor that binds to the B site of the immunoglobulin light chain gene enhancer in B lymphocytes (1), transcription factor NFB is crucial for the inducible expression of many genes involved in immunity and inflammation (2). NFB is a member of the rel multigene family and comprises five major proteins: p50, p65 (RelA), c-rel, p52, and RelB (3). The most abundant form of NFB is the heterodimer of p50 and p65 that is retained in the cytosol by specific inhibitory proteins termed IB (2). IB kinases are central to NFB activation (4 -6). The IB kinases trigger the phosphorylation of IB on amino-terminal serine residues 32 and 36, upon which the conjugation of ubiquitin occurs, and then targets the phosphorylated IB for degradation by proteasomes (6). The released nucleophilic heterodimer then moves to the nucleus, where both p50 and p65 contribute to NFB DNA binding (3). The p65 subunit is responsible for transc...

There is increasing evidence that oxidative stress is of pathophysiological importance in cardiovascular disease. Mechanical forces such as pulsatility may also contribute. Using human coronary artery smooth muscle cells (HCAS), we tested the hypothesis that stretch-induced cell proliferation is associated with oxidative stress. Stretch induced DNA synthesis in HCAS, and this was prevented by the antioxidants N-acetylcysteine and pyrrolidinedithiocarbamate (PDTC). Pulsatile stretch also increased superoxide production from HCAS in a time- and stretch dependent manner. Stretch-induced superoxide production was inhibited by diphenyleneiodoniumchloride, an NADPH oxidase inhibitor, and p-chloromercuriphenylsulfonic acid, an NADH oxidase inhibitor, but not by the xanthine oxidase inhibitor oxypurinol or the cyclooxygenase inhibitor indomethacin. In electrophoretic mobility shift assays, tumor necrosis factor-alpha activated nuclear factor-kappa B (NF-kappa B) with a peak at approximately 3 hours, whereas pulsatile stretch showed sustained activation during stimulation for up to 24 hours. The sustained activation of NF-kappa B was abolished by cotreatment with N-acetylcysteine or PDTC. Furthermore, treatment of HCAS with antisense p65 and p50 oligodeoxynucleotides of NF-kappa B inhibited stretch-induced DNA synthesis. We propose that pulsatile stretch increases oxidative stress and, in turn, promotes DNA synthesis via NF-kappa B in cultured human coronary artery smooth muscle cells.

Musculin/MyoR is a new member of basic helix-loop-helix transcription factors, and its expression is limited to skeletal muscle precursors. Here, we report that musculin/MyoR is expressed in adult kidney side population (SP) cells and can regulate their function. SP phenotype can be used to purify stem cell–rich fractions. Microarray analysis clarified that musculin/MyoR was exclusively expressed in kidney SP cells, and the cells resided in the renal interstitial space. Musculin/MyoR-positive cells were decreased in acute renal failure, but infusion of kidney SP cells increased musculin/MyoR-positive cells and improved renal function. Kidney SP cells in reversible acute renal failure expressed a high level of renoprotective factors and leukemia inhibitory factor (LIF), but not in irreversible chronic renal failure. In cultured kidney SP cells, LIF stimulated gene expression of renoprotective factors, and down-regulation of musculin/MyoR augmented LIF-induced gene expression. Our results suggest that musculin/MyoR may play important roles not only in developmental processes but also in regenerative processes in adult tissue.