# SIRT3 regulates cardiolipin biosynthesis in pressure overload-induced cardiac remodeling by PPARγ-mediated mechanism

## TL;DR

This study shows that SIRT3 helps protect the heart from damage by regulating cardiolipin production through PPARγ, offering a new target for heart failure treatment.

## Contribution

The study reveals a novel mechanism where SIRT3 regulates cardiolipin biosynthesis via PPARγ to protect against cardiac remodeling.

## Key findings

- SIRT3 knockout mice showed worse cardiac remodeling and mitochondrial dysfunction under pressure overload.
- SIRT3 overexpression improved mitochondrial function and cardiolipin levels in cardiomyocytes.
- PPARγ is involved in SIRT3's protective effects, as its antagonist reduced these benefits.

## Abstract

Cardiac remodeling is the primary pathological feature of chronic heart failure (HF). Exploring the characteristics of cardiac remodeling in the very early stages of HF and identifying targets for intervention are essential for discovering novel mechanisms and therapeutic strategies. Silent mating type information regulation 2 homolog 3 (SIRT3), as a major mitochondrial nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, is required for mitochondrial metabolism. However, whether SIRT3 plays a role in cardiac remodeling by regulating the biosynthesis of mitochondrial cardiolipin (CL) is unknown. In this study, we induced pressure overload in wild-type (WT) and SIRT3 knockout (SIRT3−/−) mice via transverse aortic constriction (TAC). Compared with WT mouse hearts, the hearts of SIRT3−/− mice exhibited more-pronounced cardiac remodeling and fibrosis, greater reactive oxygen species (ROS) production, decreased mitochondrial-membrane potential (ΔΨm), and abnormal mitochondrial morphology after TAC. Furthermore, SIRT3 deletion aggravated TAC-induced decrease in total CL content, which might be associated with the downregulation of the CL synthesis related enzymes cardiolipin synthase 1 (CRLS1) and phospholipid-lysophospholipid transacylase (TAFAZZIN). In our in vitro experiments, SIRT3 overexpression prevented angiotensin II (AngII)- induced aberrant mitochondrial function, CL biosynthesis disorder, and peroxisome proliferator-activated receptor gamma (PPARγ) downregulation in cardiomyocytes; meanwhile, SIRT3 knockdown exacerbated these effects. Moreover, the addition of GW9662, a PPARγ antagonist, partially counteracted the beneficial effects of SIRT3 overexpression. In conclusion, SIRT3 regulated PPARγ-mediated CL biosynthesis, maintained the structure and function of mitochondria, and thereby protected the myocardium against cardiac remodeling.