Evaluation of the AMPK-BACH1-NRF2 Axis as a Therapeutic Target for Inherited DCM

Dilated cardiomyopathy (DCM)-associated heart failure is a leading cause of death. About a third of all DCM is caused by variants in genes controlling heart muscle structure and/or function. Although this information is improving patient management, it has not yet led to new therapeutics. This proposal is to evaluate the potential of activating the AMPK-BACH1-NRF2 signaling pathway to treat

inherited forms of DCM. The pathway emerged from an unbiased, high-throughput functional genomics screen to discover novel therapeutic targets and signaling pathways capable of restoring contractile function in human induced pluripotent stem cell cardiomyocytes (hiPSC-CMs) harboring DCM-causing mutations. The screen and

subsequent validation experiments revealed that activation of the AMPK-BACH1-NRF2 pathway restored contractility of multiple patients’ hiPSC-CMs carrying the DCM-causing TNNT2 R173W mutation. The magnitude of the effect was comparable to CRISPR-mediated correction of the mutation. Importantly, activation of the

pathway had no effect on healthy (isogenic control) hiPSC-CMs, suggesting that the therapeutic response is specific for the disease context. Modulation of AMPK, BACH1 and NRF2 have been reported to elicit protective effects in ischemic heart disease models but these targets are largely unexplored in the context of inherited DCM. The proposed Specific Aims

address critical issues necessary to advance targeting this pathway to treat inherited DCM. AIM 1 explores the selectivity of pathway activation for restoring contractile function in different forms of inherited DCM, including disease caused by mutations in myofilament (TNNT2, MYH7 and TTN) and non-myofilament (PLN, RBM20,

LMNA) genes. We expect that the pathway will ameliorate contractile dysfunction in multiple forms of DCM. AIM 2 will define the mechanism(s) of action by identifying specific genes downstream of pathway activation that are essential to restore contractile function. Our hypothesis is that the pathway converges on a subset of NRF2-

target genes. AIM 3 explores whether activating the pathway restores contractile function by normalizing metabolic and/or ER/SR stress. Finally, AIM 4 tests whether activating the pathway will mitigate clinical features of DCM using an established mouse model. A successful outcome of this project will constitute a mechanism-based approach to treat inherited DCM. The

project uses both human patient iPSC models and mouse transgenic models to integrate human cellular context with whole organism physiology. The outcome will define mechanism(s) of action that might not only benefit inherited DCM but also inform the development of novel strategies to treat acquired forms of DCM.