IκB Kinase, a Molecular Target for Inhibition by 4-Hydroxy-2-nonenal

Abstract

Aldehydes are products and propagators of oxidative stress (1). They are reactive electrophiles that form adducts to protein and DNA that have been detected in tissues from healthy human beings and individuals with various diseases (2-6). Consequently, aldehydes modulate the activities of numerous proteins, induce mutations, and alter cell cycle progression (7-12). For example, malondialdehyde, a major carbonyl product of lipid peroxidation, is mutagenic and carcinogenic and induces cell cycle arrest at the G 1 /S and G 2 /M checkpoints (7). The G 1 /S arrest in human colon and lung cancer cells (RKO and H1299, respectively) is caused by induction of the cyclin-dependent kinase inhibitor, p21, whereas the G 2 /M arrest appears to be due to a reduction in the level of the cdc2 kinase. Thus, alteration of gene expression triggered by protein or DNA damage may contribute to the range of biological effects exerted by aldehydes.A panoply of pathophysiological responses is also exerted by 4-hydroxynonenal (HNE), 1 the major toxic product of lipid peroxidation (1). HNE reacts with sulfhydryl and amino groups and leads to inactivation of DNA polymerases, dehydrogenases, and various transporters, inter alia (13). It also causes cell cycle arrest and apoptosis (8 -10). HNE treatment of cells alters the expression of several transcription factors including c-Myc (12), c-Myb (14), and c-Jun (15), suggesting that it may have more global effects on protein expression and cell function. The induction of c-Jun by HNE is associated with activation of JNK kinase and p38 kinase, perhaps by H 2 O 2 modulation of upstream signaling pathways (15, 16).A major signaling pathway associated with inflammation and oxidative stress is mediated by the transcription factor NF-B (17-19). NF-B consists of heterodimers of two polypeptides, p50 and p65, which are members of a family of proteins related to the proto-oncogene c-rel (20, 21). Inactive NF-B is located in the cytosol, bound to its inhibitory protein, IB. Dissociation of NF-B from IB is a critical step in NF-B activation that leads to translocation of NF-B to the nucleus, enabling DNA binding and transactivation (22). This process is triggered by sequential phosphorylation and ubiquitination of IB␣, followed by digestion of the ubiquinated protein by the proteasome (23-25). The enzyme that catalyzes the ubiquitination of phosphorylated IB is constitutively active. Hence, in most cases, the key event for NF-B activation is phosphorylation of two serine residues at the N terminus of IB by IB kinase (IKK) (23,24).We report here that treatment of RKO and H1299 cells with HNE leads to a dramatic loss of DNA binding and transcriptional activation by NF-B in cells treated with tetradecanoylphorbol acetate (TPA) and ionomycin (IM). The loss of NF-B activity is due to stabilization to the IB␣-NF-B complex, which results from a decrease in the rate of turnover of IB␣. The prevention of IB␣ turnover is attributable to the inhibition of IKK caused by direct reaction with HNE. These findings indica...

Conditional Expression of 15-Lipoxygenase-1 Inhibits the Selenoenzyme Thioredoxin Reductase

“…However, inhibition of TrxR persisted for 8 h (Fig. 3B), consistent with irreversible, autoinactivation that accompanies lipid peroxidase catalysis (45)(46)(47), or with irreversible inactivation by 4-HNE reported for other enzymes (48) and selenoenzymes (49).…”

Enhanced intrarenal oxidative stress and angiotensinogen in IgA nephropathy patients

“…The latter is generated by bind 2'-deoxyribose to 8-oxo-guanie [41]. Among the formed aldehydes, 4-HNE is the major product of lipid peroxidation, and it has been suggested to play a major role in tissue toxicity associated with lipid peroxidation [42]. The isoprostanes are a family of eicosanoids of non-enzymatic origin produced by the random oxidation of tissue phospholipids by oxygen radicals.…”

Nuclear transcription factor-κB as a target for cancer drug development

“…238 Recently, 4-hydroxy-2-nonenal, a lipid peroxidation product, has been shown to block phosphorylation by direct inhibition of IKK. 239 Also, a novel peptide that selectively blocks the association of IKK-␥ (NEMO) with the rest of the IKK complex has been shown to inhibit NF-B activation in response to pro-inflammatory cytokines in mice while preserving basal NF-B activity. 240 …”