Regulation of titin-based cardiac stiffness by unfolded domain oxidation (UnDOx)

Loescher, Christine; Breitkreuz, Martin; Li, Yong; Nickel, Alexander; Unger, Andreas; Dietl, Alexander; Schmidt, Andreas; Mohamed, Belal A.; Kötter, Sebastian; Schmitt, Joachim P.; Krüger, Marcus; Krüger, Martina; Toischer, Karl; Maack, Christoph; Leichert, Lars I.; Hamdani, Nazha; Linke, Wolfgang A.

doi:10.1073/pnas.2004900117

Cited by 43 publications

(48 citation statements)

References 42 publications

(100 reference statements)

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“…Unfolded domain oxidation (UnDOx) within the titin filament was recently reported to alter titin-based properties 35 . Many pathologies including ischemia are linked to alterations of the oxidative state.…”

Section: Discussionmentioning

confidence: 99%

E3-ligase knock down revealed differential titin degradation by autophagy and the ubiquitin proteasome system

Müller

Salcan

Bongardt

et al. 2021

Sci Rep

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The sarcomere protein titin is a major determinant of cardiomyocyte stiffness and ventricular distensibility. The constant mechanical stress on titin requires well-controlled protein quality control, the exact mechanisms of which have not yet been fully elucidated. Here, we analyzed E3-ligases potentially responsible for cardiac titin ubiquitination and specifically studied the involvement of the autophagosomal system in titin degradation. Pharmacological inhibition of autophagy and the proteasome in cultured primary rat cardiomyocytes significantly elevated titin ubiquitination and increased titin degradation. Using in-vitro pull down assays we identified binding of E3-ligases MuRF1-3, CHIP and Fbx32 to several titin domains. Immunofluorescence analysis showed sarcomeric localization of the E3-ligases. siRNA-mediated knock-down of the E3-ligases MuRF-1, -3 and a combination of CHIP/Fbx32 significantly reduced autophagy-related titin ubiquitination, whereas knock-down of MuRF-2 and -3 reduced proteasome-related titin ubiquitination. We demonstrated that the proteasomal and the autophagosomal-lysosomal system participate in degradation of the titin filament. We found that ubiquitination and degradation of titin are partially regulated by E3-ligases of the MuRF family. We further identified CHIP and Fbx32 as E3-ligases involved in titin ubiquitination.

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Section: Discussionmentioning

confidence: 99%

E3-ligase knock down revealed differential titin degradation by autophagy and the ubiquitin proteasome system

Müller

Salcan

Bongardt

et al. 2021

Sci Rep

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“…In case of the giant muscle protein titin, reversible oxidation was recently shown to reduce the protein's elasticity through preferential modification of mechanosensitive Ig domains in the I‐band region of the muscle sarcomere (Loescher et al , 2020 ). This process, termed unfolded domain oxidation (UnDOx), increases cardiac stiffness under mechanical force and oxidative stress.…”

Section: Protein Triage Under Mechanical Stressmentioning

confidence: 99%

Maintaining proteostasis under mechanical stress

et al. 2021

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Cell survival, tissue integrity and organismal health depend on the ability to maintain functional protein networks even under conditions that threaten protein integrity. Protection against such stress conditions involves the adaptation of folding and degradation machineries, which help to preserve the protein network by facilitating the refolding or disposal of damaged proteins. In multicellular organisms, cells are permanently exposed to stress resulting from mechanical forces. Yet, for long time mechanical stress was not recognized as a primary stressor that perturbs protein structure and threatens proteome integrity. The identification and characterization of protein folding and degradation systems, which handle force‐unfolded proteins, marks a turning point in this regard. It has become apparent that mechanical stress protection operates during cell differentiation, adhesion and migration and is essential for maintaining tissues such as skeletal muscle, heart and kidney as well as the immune system. Here, we provide an overview of recent advances in our understanding of mechanical stress protection.

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“…In addition to the reported correlation between phosphorylation changes and diastolic heart function (Chiao et al, 2020), there are indications that oxidative changes may also contribute to elamipretide's improvement of diastolic function in aged hearts. A recent study has revealed that cardiac stiffness is heavily influenced by the oxidation of cysteine residues along titin (Loescher et al, 2020), and many of these same residues showed enhanced S-glutathionylation with age that was reversed by elamipretide treatment in our analysis. The combined lower oxidation of essential mitochondrial and cardiac proteins may be one of the core mechanisms by which elamipretide is able to drastically improve the function of aged hearts.…”

Section: Mitochondrial Thiols Are Heavily Oxidized With Age But Elamipretide Rapidly Reverses These Changesmentioning

confidence: 53%

Elamipretide (SS-31) Treatment Attenuates Age-Associated Post-Translational Modifications of Heart Proteins

Whitson

Martín-Pérez

Zhang

et al. 2021

Preprint

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It has been demonstrated that elamipretide (SS-31) rescues age-related functional deficits in the heart but the full set of mechanisms behind this have yet to be determined. We investigated the hypothesis that elamipretide influences post-translational modifications to heart proteins. The S-glutathionylation and phosphorylation proteomes of mouse hearts were analyzed using shotgun proteomics to assess the effects of aging on these post-translational modifications and the ability of the mitochondria-targeted drug elamipretide to reverse age-related changes. Aging led to an increase in oxidation of protein thiols demonstrated by increased S-glutathionylation of cysteine residues on proteins from Old (24 months old at the start of the study) mouse hearts compared to Young (5-6 months old). This shift in the oxidation state of the proteome was almost completely reversed by 8-weeks of treatment with elamipretide. Many of the significant changes that occurred were in proteins involved in mitochondrial or cardiac function. We also found changes in the mouse heart phosphoproteome that were associated with age, some of which were partially restored with elamipretide treatment. Parallel reaction monitoring of a subset of phosphorylation sites revealed that the unmodified peptide reporting for Myot S231 increased with age, but not its phosphorylated form and that both phosphorylated and unphosphorylated forms of the peptide covering cMyBP-C S307 increased, but that elamipretide treatment did not affect these changes. These results suggest that changes to thiol redox state and phosphorylation status are two ways in which age may affect mouse heart function, which can be restored by treatment with elamipretide.

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Regulation of titin-based cardiac stiffness by unfolded domain oxidation (UnDOx)

Cited by 43 publications

References 42 publications

E3-ligase knock down revealed differential titin degradation by autophagy and the ubiquitin proteasome system

E3-ligase knock down revealed differential titin degradation by autophagy and the ubiquitin proteasome system

Maintaining proteostasis under mechanical stress

Elamipretide (SS-31) Treatment Attenuates Age-Associated Post-Translational Modifications of Heart Proteins

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