Role of the ubiquitin-proteasome system in cardiac dysfunction of adipose triglyceride lipase-deficient mice.
Bottom Line: Dysfunction of the UPS was accompanied by activation of NF-κB signaling.Chronic treatment of ATGL-deficient mice with the PPARα agonist Wy14,643 improved proteasomal function, prevented NF-κB activation and decreased oxidative stress.In summary, our data point to a hitherto unrecognized link between proteasomal function, PPARα signaling and cardiovascular disease.
Affiliation: Department of Pharmacology and Toxicology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria. Electronic address: email@example.com.Show MeSH
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Mentions: Cardiac oxidative stress was assayed as mRNA expression of the two major cardiac NADPH oxidase isoforms (NOX), NOX2 and NOX4, as well as protein expression of the NOX2 cytosolic activator subunits p47phox and p67phox. As shown in Fig. 4A, NOX2 mRNA was significantly upregulated in AKO animals. This effect was significantly decreased in AKO animals treated with the PPARα agonist Wy14,643. In contrast, upregulation of NOX4 mRNA in AKO animals persisted upon Wy14,643-treatment (Fig. 4B). In accordance with NOX2 mRNA levels, p47phox protein showed an ~ 8-fold upregulation in cardiac homogenates of AKO mice. Upon Wy14,643 treatment, protein expression of p47phox was significantly reduced compared to untreated AKOs but was still ~ 6-fold increased compared to WT controls (Fig. 4C). By contrast, ~ 8-fold increased protein expression of p67phox observed in AKO hearts persisted upon Wy14,643 treatment (Fig. 4D). To test for the anti-oxidative capacity, catalase and SOD-1 protein expression was measured in cardiac homogenates of WT, AKO, WT/cTg, and AKO/cTg mice. SOD-1 protein was significantly decreased in AKO hearts, an effect that was not affected by Wy14,643 treatment (Fig. 4E). Protein expression of catalase, which triggers decomposition of hydrogen peroxide, was similar in all experimental groups (Fig. 4F). To investigate if partially reduced mRNA and protein levels of distinct NOX subunits have an impact on NADPH oxidase activity, lucigenin-derived chemiluminescence was measured in cardiac homogenates of untreated and Wy14,643-supplemented animals. As shown in Fig. 4G, ATGL deficiency resulted in more than 3-fold higher chemiluminescence production compared to WT. Treatment with the PPARα agonist Wy14,643 significantly reversed the effect of ATGL deficiency. Preincubation with the superoxide scavenging enzyme SOD-1 diminished chemiluminescence in all experimental groups to an equal extent (56 ± 2.6%). Representative Western blots are illustrated in Fig. 4H.
Affiliation: Department of Pharmacology and Toxicology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria. Electronic address: firstname.lastname@example.org.