CPT1B K321 crotonylation contributes to cardiac dysfunction in endotoxic shock

Area of Science:

• Biochemistry
• Molecular Biology
• Cardiovascular Research

Background:

• Lysine crotonylation (Kcr) is an evolutionarily conserved posttranslational modification.
• The role of Kcr in endotoxic shock-induced cardiomyopathy remains unclear.

Purpose of the Study:

• Investigate the role of Kcr in lipopolysaccharide (LPS)-induced endotoxic shock.
• Identify specific Kcr modifications and their impact on cardiac function.
• Elucidate the molecular mechanisms underlying Kcr-mediated cardiac pathology.

Main Methods:

• Established a rat model of endotoxic shock using LPS injection.
• Performed crotonylproteomic analysis on myocardial tissues.
• Utilized cell culture (primary cardiomyocytes, H9C2 cells) and in vivo cardiac-specific gene delivery (AAV9 vector).
• Employed site-directed mutagenesis and liquid chromatography-tandem mass spectrometry.

Main Results:

• Identified significant upregulation of carnitine palmitoyltransferase 1B (CPT1B) Kcr at the K321 site in LPS-treated hearts, cardiomyocytes, and H9C2 cells.
• Demonstrated that K321 Kcr impairs CPT1B activity, leading to lipid droplet deposition and mitochondrial dysfunction.
• Showed that mutating K321 to arginine (K321R) prevented Kcr, alleviated cardiac pathology, and improved mitochondrial function.
• Revealed that P300 and CBP are involved in CPT1B Kcr, with LPS promoting P300 binding and Kcr by causing CBP dissociation.

Conclusions:

• Lysine crotonylation of CPT1B at K321 is a key event in LPS-induced endotoxic shock-related cardiomyopathy.
• Targeting CPT1B Kcr, specifically the K321 site, offers a protective strategy against cardiac dysfunction.
• The CBP/P300 axis regulates CPT1B Kcr, providing mechanistic insights into sepsis-induced cardiac injury.