Cardiac-specific Mst1 Deficiency Inhibits ROS-mediated JNK Signalling to Alleviate Ang II-induced Cardiomyocyte Apoptosis.

Apoptosis is associated with various myocardial diseases. Angiotensin II (Ang II) plays a central role in the pathogenesis of RAAS-triggered cardiac apoptosis. Our previous studies showed that mammalian Ste20-like kinase 1 (Mst1) aggravates cardiac dysfunction in cardiomyocyte under pathological conditions, but its role in Ang II-mediated cardiomyocyte apoptosis is not known. We addressed this in the present study by investigating whether cardiac-specific Mst1 knockout can alleviate Ang II-induced cardiomyocyte apoptosis along with the underlying mechanisms. In vitro and in vivo experiments showed that Ang II increased intracellular reactive oxygen species (ROS) production and cardiomyocyte apoptosis; these were reversed by administration of the ROS scavenger N-acetylcysteine and by Mst1 deficiency, which suppressed c-Jun N-terminal kinase (JNK) phosphorylation and downstream signaling. Interestingly, Mst1 knockout failed to alleviate Ang II-induced phosphorylation of extracellular signal-regulated kinase 1/2, and inactivated apoptosis signal-regulating kinase1 (ASK1) by promoting its association with thioredoxin (Trx), which reversed the Ang II-induced activation of the ASK1-JNK pathway and suppressed Ang II-induced cardiomyocyte apoptosis. Thus, cardiac-specific Mst1 knockout inhibits ROS-mediated JNK signalling to block Ang II-induced cardiomyocyte apoptosis, suggesting Mst1 as a potential therapeutic target for treatment of RAAS-activated heart failure.