leupeptins and Cardiovascular-Diseases

So far, cardiovascular and renal diseases have brought us not only huge economic burden but also serious society problems. Since effective therapeutic strategies are still limited, to find new methods for the prevention or therapy of these diseases is important. Oxidative stress has been found to play a critical role in the initiation and progression of cardiovascular and renal diseases. In addition, activation of nuclear-factor-E2-related-factor-2- (Nrf2-) antioxidant-responsive element (ARE) signaling pathway protects cells and tissues from oxidative damage. As a proteasomal inhibitor, MG132 was reported to activate Nrf2 expression and function, which was accompanied with significant preventive and/or therapeutic effect on cardiovascular and renal diseases under most conditions; therefore, MG132 seems to be a potentially effective drug to be used in the prevention of oxidative damage. In this paper, we will summarize the information available regarding the effect of MG132 on oxidative stress-induced cardiovascular and renal damage, especially through Nrf2-ARE signaling pathway.

Topics: Animals; Antioxidant Response Elements; Cardiovascular Diseases; Humans; Kidney Diseases; Leupeptins; NF-E2-Related Factor 2; Oxidative Stress; Proteasome Endopeptidase Complex; Signal Transduction; Ubiquitin

Oxidative stress is believed to cause endothelial dysfunction, an early event and a hallmark in cardiovascular diseases (CVD) including hypertension, diabetes, and dyslipidemia. However, the targets for oxidative stress-mediated endothelial dysfunction in CVD have not been completely elucidated. Here we report that 26S proteasome activation by peroxynitrite (ONOO(-)) is a common pathway for endothelial dysfunction in mouse models of diabetes, hypertension, and dyslipidemia. Endothelial function, assayed by acetylcholine-induced vasorelaxation, was impaired in parallel with significantly increased 26S proteasome activity in aortic homogenates from streptozotocin (STZ)-induced type I diabetic mice, angiotensin-infused hypertensive mice, and high fat-diets-fed LDL receptor knockout (LDLr(-/-)) mice. The elevated 26S proteasome activities were accompanied by ONOO(-)-mediated PA700/S10B nitration and increased 26S proteasome assembly and caused accelerated degradation of molecules (such as GTPCH I and thioredoxin) essential to endothelial homeostasis. Pharmacological (administration of MG132) or genetic inhibition (siRNA knockdown of PA700/S10B) of the 26S proteasome blocked the degradation of the vascular protective molecules and ablated endothelial dysfunction induced by diabetes, hypertension, and western diet feeding. Taken together, these results suggest that 26S proteasome activation by ONOO(-)-induced PA700/S10B tyrosine nitration is a common route for endothelial dysfunction seen in mouse models of hypertension, diabetes, and dyslipidemia.

Topics: Animals; Blotting, Western; Cardiovascular Diseases; Cells, Cultured; Cysteine Proteinase Inhibitors; Diabetes Mellitus, Experimental; Dyslipidemias; Endothelium, Vascular; Enzyme Activation; Human Umbilical Vein Endothelial Cells; Humans; Hypertension; Leupeptins; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitrosation; Peroxynitrous Acid; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Subunits; Receptors, LDL; Risk Factors; RNA Interference; Thioredoxins; Tyrosine

Recent epidemiologic studies clearly showed that early intensive glucose control has a legacy effect for preventing diabetic macrovascular complications. However, the cellular and molecular processes by which high glucose leads to macrovascular complications are poorly understood. Vascular smooth muscle cell (VSMC) dysfunction due to high glucose is a characteristic of diabetic vascular complications. Activation of nuclear factor-κB (NF-κB) may play a key role in the regulation of inflammation and proliferation of VSMCs. We examined whether VSMC proliferation and plasminogen activator inhibitor-1 (PAI-1) expression induced by high glucose were mediated by NF-κB activation. Also, we determined whether selective inhibition of NF-κB would inhibit proliferation and PAI-1 expression in VSMCs. VSMCs of the aorta of male SD rats were treated with various concentrations of glucose (5.6, 11.1, 16.7, and 22.2 mM) with or without an inhibitor of NF-κB or expression of a recombinant adenovirus vector encoding an IκB-α mutant (Ad-IκBαM). VSMC proliferation was examined using an MTT assay. PAI-1 expression was assayed by real-time PCR and PAI-1 protein in the media was measured by ELISA. NF-κB activation was determined by immunohistochemical staining, NF-κB reporter assay, and immunoblotting. We found that glucose stimulated VSMC proliferation and PAI-1 expression in a dose-dependent manner up to 22.2 mM. High glucose (22.2 mM) alone induced an increase in NF-κB activity. Treatment with inhibitors of NF-κB such as MG132, PDTC or expression of Ad-IκB-αM in VSMCs prevented VSMC proliferation and PAI-1 expression induced by high glucose. In conclusion, inhibition of NF-κB activity prevented high glucose-induced VSMC proliferation and PAI-1 expression.

Topics: Animals; Aorta; Cardiovascular Diseases; Cell Proliferation; Cells, Cultured; Diabetes Complications; Gene Expression Regulation; Glucose; Leupeptins; Male; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NF-kappa B; Plasminogen Activator Inhibitor 1; Proline; Rats; Rats, Sprague-Dawley; Thiocarbamates

We have shown previously that non-toxic inhibition of the ubiquitin-proteasome system upregulates antioxidative defence mechanisms and protects endothelial cells from oxidative stress. Here, we have addressed the question whether the induction of antioxidative enzymes contributes to cardioprotection by non-toxic proteasome inhibition.. Treatment with 0.5 micromol/L MG132 for 48 h proved to be non-toxic and protected neonatal rat cardiac myocytes against H(2)O(2)-mediated oxidative stress in lactate dehydrogenase assays. This correlated with reduced levels of intracellular reactive oxygen species as determined by loading myocytes with dichlorofluorescein. Immunoblots showed significant upregulation of superoxide dismutase 1 (SOD1), haem oxygenase 1, and catalase upon proteasome inhibition. Luciferase assays using a reporter driven by the SOD1 promoter revealed proteasome inhibitor-mediated induction of luciferase activity. Deletion and mutation analyses identified an antioxidant response element (ARE) in the SOD1 promoter to be not only essential but also sufficient for transcriptional upregulation by proteasome inhibition. An essential role for the antioxidative transcription factor NF-E2-related factor 2 (Nrf2)-which was stabilized by proteasome inhibition-in ARE-mediated transcriptional activation was revealed in cardiac myocytes from Nrf2 wild-type and knockout mice: proteasome inhibition upregulated antioxidative enzymes and conferred protection against H(2)O(2)-mediated oxidative stress in Nrf2 wild-type cells. In contrast, the induction of antioxidative enzymes and cytoprotection were completely abolished in cardiac myocytes from Nrf2 knockout mice.. Non-toxic proteasome inhibition upregulates antioxidative enzymes via an Nrf2-dependent transcriptional activation of AREs and confers cardioprotection.

Topics: Animals; Animals, Newborn; Antioxidants; Binding Sites; Cardiovascular Agents; Cardiovascular Diseases; Catalase; Cells, Cultured; Gene Expression Regulation, Enzymologic; Heme Oxygenase-1; Hydrogen Peroxide; L-Lactate Dehydrogenase; Leupeptins; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocytes, Cardiac; NF-E2-Related Factor 2; Oxidants; Oxidative Stress; Protease Inhibitors; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Rats; Rats, Wistar; Reactive Oxygen Species; Response Elements; Superoxide Dismutase; Superoxide Dismutase-1; Time Factors; Transcription, Genetic; Transfection