Novel Keap1-Nrf2 Protein-Protein Interaction Inhibitor UBE-1099 Ameliorates Progressive Phenotype in Alport Syndrome Mouse Model

BACKGROUND

Bardoxolone methyl activates nuclear factor erythroid 2-related factor 2 (Nrf2) via covalent binding and irreversible inhibition of Kelch-like ECH-associated protein 1 (Keap1), the negative regulator of Nrf2. Ongoing clinical trials of bardoxolone methyl show promising effects for patients with CKD. However, the direct inhibition of Keap1-Nrf2 protein-protein interaction (PPI) as an approach to activate Nrf2 is less explored.

METHODS

We developed a noncovalent Nrf2 activator UBE-1099, which highly selectively inhibits Keap1-Nrf2 PPI, and evaluated its efficacy on the progressive phenotype in an Alport syndrome mouse model (Col4a5-G5X).

RESULTS

Similar to bardoxolone methyl, UBE-1099 transiently increased proteinuria and reduced plasma creatinine in Alport mice. Importantly, UBE-1099 improved the glomerulosclerosis, renal inflammation, and fibrosis, and prolonged the life span of Alport mice. UBE-1099 ameliorated the dysfunction of Nrf2 signaling in the renal tissue of Alport mice. Moreover, transcriptome analysis in the glomerulus showed that UBE-1099 induced the expression of genes associated with the cell cycle and cytoskeleton, which may explain its unique mechanism of improvement such as glomerular morphologic change.

CONCLUSIONS

UBE-1099 significantly ameliorates the progressive phenotype in Alport mice. Our results revealed the efficacy of Keap1-Nrf2 PPI inhibitor for glomerulosclerosis and present a potential therapeutic drug for CKD.

Sevoflurane post-conditioning increases nuclear factor erythroid 2-related factor and haemoxygenase-1 expression via protein kinase C pathway in a rat model of transient global cerebral ischaemia

BACKGROUND

The antioxidant mechanism of sevoflurane post-conditioning-induced neuroprotection remains unclear. We determined whether sevoflurane post-conditioning induces nuclear factor erythroid 2-related factor (Nrf2, a master transcription factor regulating antioxidant defence genes) and haemoxygenase-1 (HO-1, an antioxidant enzyme) expression, and whether protein kinase C (PKC) is involved in Nrf2 activation, in a rat model of transient global cerebral ischaemia/reperfusion (I/R) injury.

METHODS

Eighty-six rats were assigned to five groups: sham (n=6), control (n=20), sevoflurane post-conditioning (two cycles with 2 vol% sevoflurane inhalation for 10 min, n=20), chelerythrine (a PKC inhibitor; 5 mg kg(-1) i.v. administration, n=20), and sevoflurane post-conditioning plus chelerythrine (n=20). The levels of nuclear Nrf2 and cytoplasmic HO-1 were assessed 1 or 7 days after ischaemia (n=10 each, apart from the sham group, n=3).

RESULTS

On day 1 but not day 7 post-ischaemia, Nrf2 and HO-1 expression were significantly higher in the sevoflurane post-conditioning group than in the control group. Chelerythrine administration reduced the elevated Nrf2 and HO-1 expression induced by sevoflurane post-conditioning.

CONCLUSIONS

Sevoflurane post-conditioning increased Nrf2/HO-1 expression via PKC signalling in the early phase after transient global cerebral I/R injury, suggesting that activation of antioxidant enzymes may be responsible for sevoflurane post-conditioning-induced neuroprotection in the early phase after cerebral I/R injury.

Nuclear factor E2-related factor 2 dependent overexpression of sulfiredoxin and peroxiredoxin III in human lung cancer

BACKGROUND/AIMS

Oxidative stress results in protein oxidation and is implicated in carcinogenesis. Sulfiredoxin (Srx) is responsible for the enzymatic reversal of inactivated peroxiredoxin (Prx). Nuclear factor E2-related factor 2 (Nrf2) binds to antioxidant responsive elements and upregulates the expression of Srx and Prx during oxidative stress. We aimed to elucidate the biological functions and potential roles of Srx in lung cancer.

METHODS

To study the roles of Srx and Prx III in lung cancer, we compared the protein levels of Nrf2, Prxs, thioredoxin, and Srx in 40 surgically resected human lung cancer tissues using immunoblot and immunohistochemical analyses. Transforming growth factor-β(1), tumor necrosis factor-α, and camptothecin treatment were used to examine Prx III inactivation in Mv1Lu mink lung epithelial cells and A549 lung cancer cells.

RESULTS

Prx I and Prx III proteins were markedly overexpressed in lung cancer tissues. A significant increase in the oxidized form of a cysteine sulfhydryl at the catalytic site of Prxs was found in carcinogenic lung tissue compared to normal lung tissue. Densitometric analyses of immunoblot data revealed significant Srx expression, which was higher in squamous cell carcinoma tissue (60%, 12/20) than in adenocarcinoma (20%, 4/20). Also, Nrf2 was present in the nuclear compartment of cancer cells.

CONCLUSIONS

Srx and Prx III proteins were markedly overexpressed in human squamous cell carcinoma, suggesting that these proteins may play a protective role against oxidative injury and compensate for the high rate of mitochondrial metabolism in lung cancer.