SIRT3 deficiency impairs mitochondrial and contractile function in the heart

Area of Science:

• Biochemistry
• Cardiology
• Mitochondrial Biology

Background:

• Sirtuin 3 (SIRT3) is a mitochondrial deacetylase regulating metabolic enzymes via acetylation in extracardiac tissues.
• The specific role of SIRT3 in heart energy metabolism and mitochondrial dysfunction in cardiac diseases is largely unknown.

Purpose of the Study:

• To investigate the function of SIRT3 in regulating myocardial energetics and cardiac performance.
• To elucidate the impact of SIRT3 deficiency on cardiac function and mitochondrial health.

Main Methods:

• Utilized Sirtuin 3 knockout (SIRT3(-/-)) and wild-type (WT) mice.
• Assessed cardiac function using echocardiography and isolated working heart studies.
• Analyzed mitochondrial respiratory capacity, ATP synthesis, and protein acetylation levels via HPLC and LC-MS/MS.

Main Results:

• SIRT3(-/-) mice exhibited age-related cardiac dysfunction, reduced ejection fraction, and increased cardiac hypertrophy and fibrosis after transverse aortic constriction.
• Cardiac mitochondria from SIRT3(-/-) mice showed decreased respiratory capacity and ATP synthesis.
• Lack of SIRT3 resulted in increased acetylation of key mitochondrial metabolic enzymes, impaired fatty acid and glucose oxidation, and reduced myocardial energy charge.

Conclusions:

• SIRT3 deficiency significantly impairs cardiac mitochondrial and contractile function.
• Increased acetylation of energy metabolic proteins due to SIRT3 loss leads to myocardial energy depletion and cardiac dysfunction.
• SIRT3 plays a critical role in maintaining cardiac energy homeostasis and preventing heart failure.