Cardiac Myocyte KLF5 Regulates Ppara Expression and Cardiac Function.

Area of Science:

• Cardiovascular Biology
• Molecular Endocrinology
• Metabolic Regulation

Background:

• Fatty acid oxidation is a primary energy source for the heart, regulated by peroxisome proliferator-activated receptor alpha (PPARα).
• Reduced PPARα expression in conditions like sepsis and heart failure impairs cardiac energy metabolism.
• The transcriptional regulators of PPARα remain largely unknown.

Purpose of the Study:

• To investigate the role of Krüppel-like factor 5 (KLF5) in the transcriptional regulation of PPARα in cardiac myocytes.
• To elucidate the mechanism by which KLF5 influences PPARα expression and cardiac energetics.

Main Methods:

• Direct promoter binding assays to assess KLF5 interaction with the PPARα gene.
• Generation of cardiac myocyte-specific Klf5 knockout mice.
• Analysis of gene expression, fatty acid oxidation, ATP levels, triglyceride accumulation, and cardiac function in knockout and wild-type mice.
• Examination of KLF5 and PPARα expression in diabetic and septic mouse models.

Main Results:

• KLF5 directly binds to the PPARα promoter, activating its gene expression.
• Septic conditions involve c-Jun binding to an overlapping site, inhibiting KLF5-mediated PPARα transcription.
• Klf5 knockout in cardiac myocytes reduced PPARα expression, fatty acid oxidation, and ATP levels, leading to cardiac dysfunction and triglyceride accumulation.
• Diabetic mice exhibited parallel alterations in cardiac KLF5 and PPARα expression.

Conclusions:

• Cardiac myocyte KLF5 is a key transcriptional regulator of PPARα.
• KLF5 plays a critical role in maintaining cardiac energetics and function through PPARα regulation.
• Dysregulation of KLF5-PPARα axis contributes to cardiac dysfunction in metabolic and inflammatory diseases.