MicroRNA Control of Dilated Cardiomyopathy

Summary of Parent R01 (HL130840): Dilated cardiomyopathy (DCM)-associated heart failure is a leading cause of mortality worldwide. About a third of DCM is due to gene variants in a broad range of cardiac muscle proteins. Although this information has improved patient management, it has not yet led to new therapeutics that

target the underlying mechanisms of disease. A major roadblock is that the consequences of the DCM-causing mutations are not understood in sufficient detail to identify points of therapeutic intervention. To identify new therapeutic targets, we have identified two microRNAs that normalized contractility of DCM cardiomyocytes

comparable to CRISPR-correction of the underlying mutation. We biochemically identified their targets, identifying 203 genes, of which individual siRNA-mediated inhibition of 117 restored contractility of TNNT2 mutant DCM mutant hiPSC-CMs from different patient donors. The overarching objective of the parent R01 is to understand how the 117 miR-target genes improve DCM and

advance this information to develop novel therapeutics. The Specific Aims are to elucidate the therapeutic mechanisms of action of these genes and to understand the selectivity of particular mechanisms for different forms of inherited DCM (Aim 1); establish causal evidence of disease-modifying activity using human genetics

(Aim 2), and test whether a set of promising targets that are predicted to reduce endoplasmic reticulum (ER) stress will alleviate clinical symptoms of DCM in a mouse model (Aim 3). Proposed Supplement: The proposed administrative supplement will extend the parent R01 to evaluate existing investigational and approved drugs for repurposing based on their activities against the same processes affected

by the miR-target genes. Aim S.1 will test investigational and approved drugs for the ability to rescue the contractile deficit characteristic of DCM using hiPSC-CMs as in the parent project. Consistent with the hypothesis that many targets converge on ER stress, we will focus first on therapeutics that are known to alleviate ER stress

or act on related signaling processes such as WNT and anti-oxidant pathways. Preliminary studies have already identified two drugs that normalize dysfunction in the hiPSC-CM model. Therefore, Aim S.2 will evaluate these (plus others as they emerge from Aim S.1) in more detail by probing whether they are efficacious against

DCM caused by different gene mutations and whether they act across a range of patient genetic backgrounds. These studies will indicate how broadly the drugs can act across patients with different forms of DCM. We will employ a broad panel of DCM-causing mutations, including both myofilament and non-myofilament variants, as

proposed for Aim 1 of the parent R01. These studies will be performed by Mr. Isaac Sanchez, who is an Hispanic American. Mr. Sanchez recently earned a Bachelor’s degree and is an aspiring physician-scientist committed to a career in cardiology. Additional training components include instruction in physiology and mentoring on career advancement to support his

planned application to MD/PhD programs by the end of the supplement support period.