Cardiac-specific VLCAD deficiency induces dilated cardiomyopathy and cold intolerance

Area of Science:

• Biochemistry
• Cardiology
• Genetics

Background:

• Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency causes hypoketotic hypoglycemia and cardiomyopathy, worsened by fasting and cold.
• Global VLCAD knockout mice exhibit cardiomyopathy and fatal hypothermia upon cold exposure.
• The specific tissue contribution to these VLCAD deficiency phenotypes remains unclear.

Purpose of the Study:

• To investigate the role of cardiac VLCAD in cardiomyopathy and cold intolerance.
• To determine if cardiac-specific VLCAD deficiency is sufficient to cause these phenotypes.

Main Methods:

• Generated cardiac-specific VLCAD-deficient (cVLCAD(-/-)) mice using Cre-mediated gene ablation in cardiomyocytes.
• Assessed cardiac function and cold tolerance in cVLCAD(-/-) mice under fasting and cold stress (+5°C).

Main Results:

• cVLCAD(-/-) mice developed cardiomyopathy by 6 months of age, showing enlarged ventricles and reduced fractional shortening.
• Selective cardiac VLCAD deficiency induced severe cold intolerance, hypothermia, bradycardia, and depressed cardiac function during cold exposure and fasting.
• Cardiac-specific VLCAD deficiency was associated with reduced ATP production.

Conclusions:

• Cardiac VLCAD deficiency is sufficient to cause cardiomyopathy and cold intolerance.
• Myocardial fatty acid oxidation is essential for maintaining normal cardiac function under fasting and cold stress conditions.