PAK3 Exacerbates Cardiac Lipotoxicity via SREBP1c in Obesity Cardiomyopathy

Area of Science:

• Cardiovascular Biology
• Metabolic Disease Research
• Molecular Cardiology

Background:

• Obesity leads to lipid accumulation in cardiomyocytes, causing oxidative stress and heart failure.
• Understanding the molecular mechanisms of lipid overload is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the role of P21-activated kinase 3 (PAK3) in obesity-induced cardiac lipid accumulation.
• To identify potential therapeutic targets for ameliorating obesity cardiomyopathy.

Main Methods:

• Examined PAK3 expression in human and murine obese hearts and cardiomyocytes.
• Utilized cardiac-specific PAK3 overexpression in mice to assess diet-induced cardiac dysfunction.
• Investigated the signaling pathway involving PAK3, mTOR, S6K1, and SREBP1c.
• Assessed the effects of PAK3 knockdown and pharmacological inhibitors in cellular and animal models.

Main Results:

• PAK3 was elevated in obese myocardium and cardiomyocytes under stress.
• Overexpression of PAK3 exacerbated diet-induced cardiac dysfunction and lipid deposition.
• PAK3 promoted nuclear SREBP1c expression via mTOR/S6K1, leading to lipotoxicity and oxidative stress.
• PAK3 knockdown and inhibition of S6K1 or SREBP1c attenuated lipid overload and protected against cell death.

Conclusions:

• PAK3 plays a critical role in impairing myocardial lipid homeostasis during obesity.
• Targeting the PAK3-SREBP1c pathway represents a viable therapeutic strategy for obesity cardiomyopathy.
• Inhibiting cardiac lipotoxicity effectively mitigates cardiac dysfunction in obesity.