TRIM40 Drives Pathological Cardiac Hypertrophy and Heart Failure through PKN2 Ubiquitination

Pathological cardiac hypertrophy is a key predisposing factor for heart failure (HF). This study investigates the role of the E3 ubiquitin ligase Tripartite Motif-Containing 40 (TRIM40) in cardiac hypertrophy. Using TRIM40 knockout (TRIM40-/-) and cardiac-specific overexpressing mice, pathological hypertrophy was induced by angiotensin II (Ang II) infusion or transverse aortic constriction (TAC). Results demonstrated that TRIM40 expression was upregulated in hypertrophic hearts. TRIM40 deficiency attenuated cardiac hypertrophy and dysfunction, whereas its overexpression exacerbated pathological remodeling. Mechanistically, TRIM40 binds Protein Kinase N2 (PKN2) via its B-box domain, promoting K63-linked ubiquitination at cysteine 29 that enhances PKN2 phosphorylation at Ser815 and activates downstream signaling. Pharmacological inhibition of PKN2 attenuated cardiac remodeling induced by TRIM40 overexpression. These findings indicate that TRIM40 promotes cardiac hypertrophy through K63-linked ubiquitination and activation of PKN2, identifying TRIM40 as a potential therapeutic target for HF.