CHK1 attenuates cardiac dysfunction via suppressing SIRT1-ubiquitination

Area of Science:

• Cardiology
• Molecular Biology
• Mitochondrial Biology

Background:

• Mitochondrial dysfunction is a key factor in myocardial ischemia-reperfusion (I/R) injury.
• Checkpoint kinase 1 (CHK1) is known to promote cardiomyocyte proliferation, but its effect on mitochondrial function during I/R injury is unclear.

Purpose of the Study:

• To investigate the role of CHK1 in regulating mitochondrial function and cardiomyocyte survival following I/R injury.
• To elucidate the molecular mechanism by which CHK1 influences mitochondrial homeostasis and cardiac protection.

Main Methods:

• Generation of cardiomyocyte-specific CHK1 knockout and overexpression mouse models.
• Isolation of adult mouse cardiomyocytes for in vitro oxygen-glucose deprivation/re-oxygenation (OGD/R) studies.
• Utilized mass spectrometry-proteomics and co-immunoprecipitation assays to identify molecular targets and interactions.

Main Results:

• CHK1 expression was reduced in I/R injured myocardium and OGD/R stressed cardiomyocytes.
• CHK1 overexpression conferred protection against I/R injury, while CHK1 deficiency exacerbated cardiac dysfunction and apoptosis.
• CHK1 preserved mitochondrial metabolism, attenuated oxidative stress, and promoted mitochondrial biogenesis and mitophagy, identifying SIRT1 as a direct target phosphorylated by CHK1.

Conclusions:

• CHK1 mitigates myocardial I/R injury by enhancing mitochondrial function and promoting cardiomyocyte survival.
• The protective effects of CHK1 are mediated through a SIRT1-dependent mechanism, involving the inhibition of SIRT1 degradation.
• These findings establish CHK1 as a critical regulator of mitochondrial dynamics and a potential therapeutic target for I/R injury.