Histone LSD1 (lysine-specific demethylase 1) is an important epigenetic antitumor drug target, whose inhibitors are currently in phase I/II clinical trials. However, the potential side effects of LSD1 inhibition in the progress of cardiac remodeling to heart failure remain to be investigated.

To evaluate the roles of myofibroblast- or cardiomyocyte-specific LSD1 deficiency in pressure overload-induced cardiac remodeling.

Adult mouse cardiac fibroblasts, neonatal rat cardiac myocytes, and fibroblasts were isolated, respectively. The myofibroblast-specific and cardiomyocyte-specific LSD1 inducible knockout mice were then generated. We found that LSD1 was increased not only in human dilated cardiomyopathy hearts but also in wild-type mouse heart homogenates and isolated cardiac fibroblasts, following 20 weeks of transverse aortic constriction. The upregulation of LSD1 was also observed in Ang II-treated neonatal rat cardiac fibroblasts, which was reversed by LSD1 silence or its activity inhibition by ORY-1001. These findings suggested a potential involvement of LSD1 in cardiac remodeling. Importantly, myofibroblast-specific LSD1 inducible knockout in vivo significantly alleviated systolic dysfunction, cardiac hypertrophy, and fibrosis, following 6 and 20 weeks of transverse aortic constriction. Mechanistically, through RNA-sequencing and the following Western blot analysis, we found that loss of LSD1 in Ang II-induced myofibroblasts not only inhibited the intracellular upregulation of TGFβ1 (transforming growth factor β1), its downstream effectors Smad2/3 phosphorylation, as well as the phosphorylation of p38, ERK1/2 and JNK, but also reduced the supernatant TGFβ1 secretion, which then decreased myocyte hypertrophy in the indirect coculture model. On the other hand, cardiomyocyte-specific LSD1-inducible knockout in vivo triggered the reprogramming of fetal genes, mild cardiac hypertrophy, and dysfunction under both basal and stressed conditions.

Our findings, for the first time, implicate that myofibroblast-specific LSD1 deletion attenuates transverse aortic constriction-induced cardiac remodeling and improves heart function, suggesting that LSD1 is a potential therapeutic target for late-stage heart failure.