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Rationale: Histone lysine specific demethylase 1 (LSD1) is an important epigenetic anti-tumor 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. Objective: To evaluate the roles of myofibroblast- or cardiomyocyte-specific LSD1 deficiency in pressure overload-induced cardiac remodeling. Methods and Results: Adult mouse cardiac fibroblasts (CFs)，neonatal rat cardiac myocytes (NRCMs) and fibroblasts (NRCFs) 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 DCM (dilated cardiomyopathy) hearts, but also in wild type mouse heart homogenates and isolated CFs, following 20 weeks of transverse aortic constriction (TAC). The upregulation of LSD1 was also observed in Ang II-treated NRCFs, 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 TAC. 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 transforming growth factor β1 (TGFβ1), 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 co-culture 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. Conclusions: Our findings, for the first time, implicate that myofibroblast-specific LSD1 deletion attenuates TAC-induced cardiac remodeling and improves heart function, suggesting that LSD1 is a potential therapeutic target for late stage heart failure.

DCN1, a co-E3 ligase, interacts with UBC12 and activates cullin–RING ligases (CRLs) by catalyzing cullin neddylation. Although DCN1 has been recognized as an important therapeutic target for human diseases, its role in the cardiovascular area remains unknown. Here, we first found that DCN1 was upregulated in isolated cardiac fibroblasts (CFs) treated by angiotensin (Ang) II and in mouse hearts after pressure overload. Then, structure-based optimizations for DCN1-UBC12 inhibitors were performed based on our previous work, yielding compound DN-2. DN-2 specifically targeted DCN1 at molecular and cellular levels as shown by molecular modeling studies, HTRF, cellular thermal shift and co-immunoprecipitation assays. Importantly, DN-2 effectively reversed Ang II-induced cardiac fibroblast activation, which was associated with the inhibition of cullin 3 neddylation. Our findings indicate a potentially unrecognized role of DCN1 inhibition for anticardiac fibrotic effects. DN-2 may be used as a lead compound for further development.

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