Liver X receptors are negative regulators of cardiac hypertrophy via suppressing NF-kappaB signalling.

AIMS

Nuclear factor-kappaB (NF-kappaB) plays a critical role in cell growth and inflammation during the progression of cardiac hypertrophy and heart failure. Several members of nuclear receptor superfamily, including liver X receptors (LXRalpha and LXRbeta), have been shown to suppress inflammatory responses, but little is known about their effects in cardiomyocytes.

METHODS AND RESULTS

We investigated LXR expression patterns in pressure overload-induced hypertrophic hearts and the hypertrophic growth of the LXRalpha-deficient hearts from mice (C57/B6) in response to pressure overload. The underlying mechanisms were also explored using cultured myocytes. We found that cardiac expression of LXRalpha was upregulated in pressure overload-induced left ventricular hypertrophy in mice. Transverse aorta coarctation-induced left ventricular hypertrophy was exacerbated in LXRalpha-null mice relative to control mice. A synthetic LXR ligand, T1317, suppressed cardiomyocyte hypertrophy in response to angiotensin II and lipopolysaccharide treatments. In addition, LXR activation suppressed NF-kappaB signalling and the expression of associated inflammatory factors. Overexpression of constitutively active LXRalpha and beta in cultured myocytes suppressed NF-kappaB activity.

CONCLUSION

LXRs are negative regulators of cardiac growth and inflammation via suppressing NF-kappaB signalling in cardiomyocytes. This should provide new insights into novel therapeutic targets for treating cardiac hypertrophy and heart failure.