Proteasome malfunction activates macroautophagy in the heart

Area of Science:

• Molecular biology
• Cardiovascular research
• Cellular stress response

Background:

• Protein quality control (PQC) maintains cellular proteostasis by degrading misfolded proteins, primarily via the ubiquitin-proteasome system (UPS) and autophagy.
• Proteasome functional insufficiency (PFI) is implicated in heart diseases, with both PFI and autophagy activation observed in cardiac proteinopathies.
• A direct causal link between PFI and autophagy activation in the heart of intact animals remained unestablished.

Purpose of the Study:

• To investigate the direct causal relationship between proteasome functional insufficiency and autophagy activation in cardiomyocytes within intact animals.
• To elucidate the potential cross-talk between the ubiquitin-proteasome system and autophagy in cardiac protein quality control.

Main Methods:

• Utilized an autophagy reporter system in cardiomyocytes.
• Pharmacologically induced proteasome inhibition in both cell cultures and intact animal models.
• Assessed autophagy activation in response to proteasome inhibition.

Main Results:

• Pharmacologically induced proteasome inhibition was sufficient to activate autophagy in cardiomyocytes.
• Autophagy activation was observed in both cultured cardiomyocytes and in intact animals following proteasome inhibition.
• This demonstrates a direct link between impaired proteasome function and the activation of the autophagic pathway in cardiac cells.

Conclusions:

• Pharmacological proteasome inhibition directly triggers autophagy in cardiomyocytes, establishing a causal link.
• This finding highlights a significant cross-talk between the UPS and autophagy in cardiac protein quality control.
• Understanding this interplay is crucial for developing therapeutic strategies for heart diseases associated with proteasome dysfunction.