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Protein quality control disruption by PKCβII in heart failure; rescue by the selective PKCβII inhibitor, βIIV5-3.

Ferreira JC, Boer BN, Grinberg M, Brum PC, Mochly-Rosen D - PLoS ONE (2012)

Bottom Line: Importantly, inhibition of PKCβII, using a selective PKCβII peptide inhibitor (βIIV5-3), improved proteasomal activity and conferred protection in cultured neonatal cardiomyocytes.We also show that sustained inhibition of PKCβII increased proteasomal activity, decreased accumulation of damaged and misfolded proteins and increased animal survival in two rat models of HF.Finally, increased cardiac PKCβII activity and accumulation of misfolded proteins associated with decreased proteasomal function were found also in remodeled and failing human hearts, indicating a potential clinical relevance of our findings.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America.

ABSTRACT
Myocardial remodeling and heart failure (HF) are common sequelae of many forms of cardiovascular disease and a leading cause of mortality worldwide. Accumulation of damaged cardiac proteins in heart failure has been described. However, how protein quality control (PQC) is regulated and its contribution to HF development are not known. Here, we describe a novel role for activated protein kinase C isoform βII (PKCβII) in disrupting PQC. We show that active PKCβII directly phosphorylated the proteasome and inhibited proteasomal activity in vitro and in cultured neonatal cardiomyocytes. Importantly, inhibition of PKCβII, using a selective PKCβII peptide inhibitor (βIIV5-3), improved proteasomal activity and conferred protection in cultured neonatal cardiomyocytes. We also show that sustained inhibition of PKCβII increased proteasomal activity, decreased accumulation of damaged and misfolded proteins and increased animal survival in two rat models of HF. Interestingly, βIIV5-3-mediated protection was blunted by sustained proteasomal inhibition in HF. Finally, increased cardiac PKCβII activity and accumulation of misfolded proteins associated with decreased proteasomal function were found also in remodeled and failing human hearts, indicating a potential clinical relevance of our findings. Together, our data highlights PKCβII as a novel inhibitor of proteasomal function. PQC disruption by increased PKCβII activity in vivo appears to contribute to the pathophysiology of heart failure, suggesting that PKCβII inhibition may benefit patients with heart failure. (218 words).

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Impaired protein quality control in left ventricular remodeling and heart failure in humans.A. ATP-dependent and -independent proteasomal activity, B. oxidized protein levels (determined by Western blot) and C. polyubiquitinated protein levels (determined by Western blot) in biopsied hearts from aortic stenosis-induced left ventricular remodeling (LVR) patients (green bars), ischemic cardiomyopathy-induced heart failure patients (red bars) and autopsied non-failing human hearts (white bars). D. Negative correlation between proteasomal function and oxidized protein accumulation in failing (aortic stenosis-LVR and ischemic-HF) and non-failing heart samples. E. Total PKC levels in failing hearts compared to non-failing hearts and F. Representative blots of PKCβII and PKCα proteins in total and Triton-soluble fraction (particulate fraction) in biopsied hearts from aortic stenosis-induced left ventricular remodeling patients (n = 6, green bars) and ischemic cardiomyopathy-induced heart failure patients (n = 3, red bars) compared to autopsied non-failing human hearts (n = 6, trace). Total and Triton-soluble fractions were normalized against GAPDH and Gαo, respectively. Error bars indicate SEM. *, p<0.05 compared to control (non-failing heart). §, p<0.05 compared to aortic stenosis-LVR patients.
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pone-0033175-g006: Impaired protein quality control in left ventricular remodeling and heart failure in humans.A. ATP-dependent and -independent proteasomal activity, B. oxidized protein levels (determined by Western blot) and C. polyubiquitinated protein levels (determined by Western blot) in biopsied hearts from aortic stenosis-induced left ventricular remodeling (LVR) patients (green bars), ischemic cardiomyopathy-induced heart failure patients (red bars) and autopsied non-failing human hearts (white bars). D. Negative correlation between proteasomal function and oxidized protein accumulation in failing (aortic stenosis-LVR and ischemic-HF) and non-failing heart samples. E. Total PKC levels in failing hearts compared to non-failing hearts and F. Representative blots of PKCβII and PKCα proteins in total and Triton-soluble fraction (particulate fraction) in biopsied hearts from aortic stenosis-induced left ventricular remodeling patients (n = 6, green bars) and ischemic cardiomyopathy-induced heart failure patients (n = 3, red bars) compared to autopsied non-failing human hearts (n = 6, trace). Total and Triton-soluble fractions were normalized against GAPDH and Gαo, respectively. Error bars indicate SEM. *, p<0.05 compared to control (non-failing heart). §, p<0.05 compared to aortic stenosis-LVR patients.

Mentions: To determine the extent of PQC disruption in cardiac remodeling/failure, we used heart biopsies from seven patients with aortic stenosis-induced left ventricular remodeling who underwent aortic valve replacement. Heart biopsies from four patients with ischemic cardiomyopathy-induced HF and from autopsy specimens of 13 non-failing human hearts as controls were also examined (Table S1). Despite preserved systolic function, all patients with aortic stenosis displayed heart failure signs and symptoms, presenting functional class III–IV of the New York Heart Association [21]. Both ATP-dependent (26S) and -independent (20S) proteasomal activities were lower by about 50% in aortic stenosis and ischemic failing hearts as compared with controls (Fig. 6A) and the levels of oxidized and polyubiquitinated cardiac proteins were two to three-fold higher in these patients as compared with control subjects (Fig. 6B–C). There was a negative correlation between proteasomal function and oxidized cardiac protein accumulation in failing human hearts (R2 = 0.70, p = 0.001; Fig. 6D). There is an obvious caveat of using autopsied hearts as a control. Nevertheless, when we examined PQC, an ATP-dependent function, we found a better PQC in the autopsied samples of control subjects relative to the biopsy samples from remodeled and failing human hearts, suggesting an impaired PQC in failing human hearts.


Protein quality control disruption by PKCβII in heart failure; rescue by the selective PKCβII inhibitor, βIIV5-3.

Ferreira JC, Boer BN, Grinberg M, Brum PC, Mochly-Rosen D - PLoS ONE (2012)

Impaired protein quality control in left ventricular remodeling and heart failure in humans.A. ATP-dependent and -independent proteasomal activity, B. oxidized protein levels (determined by Western blot) and C. polyubiquitinated protein levels (determined by Western blot) in biopsied hearts from aortic stenosis-induced left ventricular remodeling (LVR) patients (green bars), ischemic cardiomyopathy-induced heart failure patients (red bars) and autopsied non-failing human hearts (white bars). D. Negative correlation between proteasomal function and oxidized protein accumulation in failing (aortic stenosis-LVR and ischemic-HF) and non-failing heart samples. E. Total PKC levels in failing hearts compared to non-failing hearts and F. Representative blots of PKCβII and PKCα proteins in total and Triton-soluble fraction (particulate fraction) in biopsied hearts from aortic stenosis-induced left ventricular remodeling patients (n = 6, green bars) and ischemic cardiomyopathy-induced heart failure patients (n = 3, red bars) compared to autopsied non-failing human hearts (n = 6, trace). Total and Triton-soluble fractions were normalized against GAPDH and Gαo, respectively. Error bars indicate SEM. *, p<0.05 compared to control (non-failing heart). §, p<0.05 compared to aortic stenosis-LVR patients.
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Related In: Results  -  Collection

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pone-0033175-g006: Impaired protein quality control in left ventricular remodeling and heart failure in humans.A. ATP-dependent and -independent proteasomal activity, B. oxidized protein levels (determined by Western blot) and C. polyubiquitinated protein levels (determined by Western blot) in biopsied hearts from aortic stenosis-induced left ventricular remodeling (LVR) patients (green bars), ischemic cardiomyopathy-induced heart failure patients (red bars) and autopsied non-failing human hearts (white bars). D. Negative correlation between proteasomal function and oxidized protein accumulation in failing (aortic stenosis-LVR and ischemic-HF) and non-failing heart samples. E. Total PKC levels in failing hearts compared to non-failing hearts and F. Representative blots of PKCβII and PKCα proteins in total and Triton-soluble fraction (particulate fraction) in biopsied hearts from aortic stenosis-induced left ventricular remodeling patients (n = 6, green bars) and ischemic cardiomyopathy-induced heart failure patients (n = 3, red bars) compared to autopsied non-failing human hearts (n = 6, trace). Total and Triton-soluble fractions were normalized against GAPDH and Gαo, respectively. Error bars indicate SEM. *, p<0.05 compared to control (non-failing heart). §, p<0.05 compared to aortic stenosis-LVR patients.
Mentions: To determine the extent of PQC disruption in cardiac remodeling/failure, we used heart biopsies from seven patients with aortic stenosis-induced left ventricular remodeling who underwent aortic valve replacement. Heart biopsies from four patients with ischemic cardiomyopathy-induced HF and from autopsy specimens of 13 non-failing human hearts as controls were also examined (Table S1). Despite preserved systolic function, all patients with aortic stenosis displayed heart failure signs and symptoms, presenting functional class III–IV of the New York Heart Association [21]. Both ATP-dependent (26S) and -independent (20S) proteasomal activities were lower by about 50% in aortic stenosis and ischemic failing hearts as compared with controls (Fig. 6A) and the levels of oxidized and polyubiquitinated cardiac proteins were two to three-fold higher in these patients as compared with control subjects (Fig. 6B–C). There was a negative correlation between proteasomal function and oxidized cardiac protein accumulation in failing human hearts (R2 = 0.70, p = 0.001; Fig. 6D). There is an obvious caveat of using autopsied hearts as a control. Nevertheless, when we examined PQC, an ATP-dependent function, we found a better PQC in the autopsied samples of control subjects relative to the biopsy samples from remodeled and failing human hearts, suggesting an impaired PQC in failing human hearts.

Bottom Line: Importantly, inhibition of PKCβII, using a selective PKCβII peptide inhibitor (βIIV5-3), improved proteasomal activity and conferred protection in cultured neonatal cardiomyocytes.We also show that sustained inhibition of PKCβII increased proteasomal activity, decreased accumulation of damaged and misfolded proteins and increased animal survival in two rat models of HF.Finally, increased cardiac PKCβII activity and accumulation of misfolded proteins associated with decreased proteasomal function were found also in remodeled and failing human hearts, indicating a potential clinical relevance of our findings.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America.

ABSTRACT
Myocardial remodeling and heart failure (HF) are common sequelae of many forms of cardiovascular disease and a leading cause of mortality worldwide. Accumulation of damaged cardiac proteins in heart failure has been described. However, how protein quality control (PQC) is regulated and its contribution to HF development are not known. Here, we describe a novel role for activated protein kinase C isoform βII (PKCβII) in disrupting PQC. We show that active PKCβII directly phosphorylated the proteasome and inhibited proteasomal activity in vitro and in cultured neonatal cardiomyocytes. Importantly, inhibition of PKCβII, using a selective PKCβII peptide inhibitor (βIIV5-3), improved proteasomal activity and conferred protection in cultured neonatal cardiomyocytes. We also show that sustained inhibition of PKCβII increased proteasomal activity, decreased accumulation of damaged and misfolded proteins and increased animal survival in two rat models of HF. Interestingly, βIIV5-3-mediated protection was blunted by sustained proteasomal inhibition in HF. Finally, increased cardiac PKCβII activity and accumulation of misfolded proteins associated with decreased proteasomal function were found also in remodeled and failing human hearts, indicating a potential clinical relevance of our findings. Together, our data highlights PKCβII as a novel inhibitor of proteasomal function. PQC disruption by increased PKCβII activity in vivo appears to contribute to the pathophysiology of heart failure, suggesting that PKCβII inhibition may benefit patients with heart failure. (218 words).

Show MeSH
Related in: MedlinePlus