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Role of the ubiquitin-proteasome system in cardiac dysfunction of adipose triglyceride lipase-deficient mice.

Mussbacher M, Stessel H, Wölkart G, Haemmerle G, Zechner R, Mayer B, Schrammel A - J. Mol. Cell. Cardiol. (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria. Electronic address: marion.mussbacher@uni-graz.at.

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Activation of NF-κB signaling in AKO hearts. Protein expression was measured in cardiac homogenates of WT (open bars), AKO (solid bars), WT/cTg (striped bars), and AKO/cTg (gray bars) mice. Protein levels of (A) IKKα but not of (B) IKKβ were significantly increased in ATGL deficiency. Protein expression of (C) NF-κB, (D) p-NF-κB and (E) IκB were raised in AKO hearts. Data were expressed as folds of WT control (WT = 1) and represent mean values ± S.E.M. of 6 individual experiments; *p < 0.05 vs WT; #p < 0.05 vs AKO. (F) Representative Western blots. (G) Cardiac mRNA levels of NF-κB target genes TNFα, MCP-1, IL-6, HO-1, and GTPCH-1 determined by qPCR were upregulated in ATGL deficiency. Data represent mean values ± S.E.M. of 5–10 individual experiments. *p < 0.05 vs WT.
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f0010: Activation of NF-κB signaling in AKO hearts. Protein expression was measured in cardiac homogenates of WT (open bars), AKO (solid bars), WT/cTg (striped bars), and AKO/cTg (gray bars) mice. Protein levels of (A) IKKα but not of (B) IKKβ were significantly increased in ATGL deficiency. Protein expression of (C) NF-κB, (D) p-NF-κB and (E) IκB were raised in AKO hearts. Data were expressed as folds of WT control (WT = 1) and represent mean values ± S.E.M. of 6 individual experiments; *p < 0.05 vs WT; #p < 0.05 vs AKO. (F) Representative Western blots. (G) Cardiac mRNA levels of NF-κB target genes TNFα, MCP-1, IL-6, HO-1, and GTPCH-1 determined by qPCR were upregulated in ATGL deficiency. Data represent mean values ± S.E.M. of 5–10 individual experiments. *p < 0.05 vs WT.

Mentions: To investigate the mechanism underlying cardiac inflammation in ATGL deficiency [13] we analyzed crucial parameters of canonical NF-κB signaling (for review, see [18]). As illustrated in Fig. 2A, cardiac ATGL deficiency led to increased protein expression of the IκB kinase (IKK) complex as IKKα protein levels were significantly elevated in homogenates of AKO mice. By contrast, IKKβ protein expression was similar in all experimental groups (Fig. 2B). Furthermore, AKO hearts showed a more than 3-fold increased NF-κB RelA/p65 protein expression that was normalized to WT levels in hearts of AKO/cTg mice (Fig. 2C). Phosphorylation of NF-κB RelA/p65 at serine 536, which is thought to activate the NF-κB complex independently of IκB release [19], was also markedly elevated in AKO hearts (Fig. 2D). However, the ratio of phosphorylated to total NF-κB protein was unaffected by ATGL knockout (data not shown). Cardiac protein levels of IκB (which reacts with NF-κB to form an inactive cytosolic complex) were increased nearly 2-fold in AKO mice (Fig. 2E). All markers of NF-κB signaling that were increased in AKO mice were restored in AKO/cTg mice. Representative Western blots are shown in Fig. 2F. Activation of cardiac NF-κB signaling was supported by qPCR experiments showing that mRNA levels of selected NF-κB target genes including TNFα, monocyte chemoattractant protein-1 (MCP-1), IL-6, heme oxygenase-1 (HO-1), and GTP cyclohydrolase 1 (GTPCH-1) were significantly increased in AKO hearts (Fig. 2G).


Role of the ubiquitin-proteasome system in cardiac dysfunction of adipose triglyceride lipase-deficient mice.

Mussbacher M, Stessel H, Wölkart G, Haemmerle G, Zechner R, Mayer B, Schrammel A - J. Mol. Cell. Cardiol. (2014)

Activation of NF-κB signaling in AKO hearts. Protein expression was measured in cardiac homogenates of WT (open bars), AKO (solid bars), WT/cTg (striped bars), and AKO/cTg (gray bars) mice. Protein levels of (A) IKKα but not of (B) IKKβ were significantly increased in ATGL deficiency. Protein expression of (C) NF-κB, (D) p-NF-κB and (E) IκB were raised in AKO hearts. Data were expressed as folds of WT control (WT = 1) and represent mean values ± S.E.M. of 6 individual experiments; *p < 0.05 vs WT; #p < 0.05 vs AKO. (F) Representative Western blots. (G) Cardiac mRNA levels of NF-κB target genes TNFα, MCP-1, IL-6, HO-1, and GTPCH-1 determined by qPCR were upregulated in ATGL deficiency. Data represent mean values ± S.E.M. of 5–10 individual experiments. *p < 0.05 vs WT.
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f0010: Activation of NF-κB signaling in AKO hearts. Protein expression was measured in cardiac homogenates of WT (open bars), AKO (solid bars), WT/cTg (striped bars), and AKO/cTg (gray bars) mice. Protein levels of (A) IKKα but not of (B) IKKβ were significantly increased in ATGL deficiency. Protein expression of (C) NF-κB, (D) p-NF-κB and (E) IκB were raised in AKO hearts. Data were expressed as folds of WT control (WT = 1) and represent mean values ± S.E.M. of 6 individual experiments; *p < 0.05 vs WT; #p < 0.05 vs AKO. (F) Representative Western blots. (G) Cardiac mRNA levels of NF-κB target genes TNFα, MCP-1, IL-6, HO-1, and GTPCH-1 determined by qPCR were upregulated in ATGL deficiency. Data represent mean values ± S.E.M. of 5–10 individual experiments. *p < 0.05 vs WT.
Mentions: To investigate the mechanism underlying cardiac inflammation in ATGL deficiency [13] we analyzed crucial parameters of canonical NF-κB signaling (for review, see [18]). As illustrated in Fig. 2A, cardiac ATGL deficiency led to increased protein expression of the IκB kinase (IKK) complex as IKKα protein levels were significantly elevated in homogenates of AKO mice. By contrast, IKKβ protein expression was similar in all experimental groups (Fig. 2B). Furthermore, AKO hearts showed a more than 3-fold increased NF-κB RelA/p65 protein expression that was normalized to WT levels in hearts of AKO/cTg mice (Fig. 2C). Phosphorylation of NF-κB RelA/p65 at serine 536, which is thought to activate the NF-κB complex independently of IκB release [19], was also markedly elevated in AKO hearts (Fig. 2D). However, the ratio of phosphorylated to total NF-κB protein was unaffected by ATGL knockout (data not shown). Cardiac protein levels of IκB (which reacts with NF-κB to form an inactive cytosolic complex) were increased nearly 2-fold in AKO mice (Fig. 2E). All markers of NF-κB signaling that were increased in AKO mice were restored in AKO/cTg mice. Representative Western blots are shown in Fig. 2F. Activation of cardiac NF-κB signaling was supported by qPCR experiments showing that mRNA levels of selected NF-κB target genes including TNFα, monocyte chemoattractant protein-1 (MCP-1), IL-6, heme oxygenase-1 (HO-1), and GTP cyclohydrolase 1 (GTPCH-1) were significantly increased in AKO hearts (Fig. 2G).

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Graz, Universitätsplatz 2, A-8010 Graz, Austria. Electronic address: marion.mussbacher@uni-graz.at.

Show MeSH
Related in: MedlinePlus