Novel Biosensor Identifies Ruxolitinib as a Potent and Cardioprotective CaMKII Inhibitor

Abstract

Ca2+/Calmodulin-dependent protein kinase II (CaMKII) hyperactivity causes heart injury and arrhythmias--two major sources of mortality worldwide. Despite proven benefits of CaMKII inhibition in numerous preclinical models of heart disease, translation of CaMKII antagonists into humans has been stymied by low potency, toxicity, and an enduring concern for adverse effects on cognition due to an established role of CaMKII in learning and memory. To address these challenges, we asked if any clinically approved drugs, developed for other purposes, were potent CaMKII inhibitors. For this, we engineered a novel fluorescent biosensor, CaMKAR (CaMKII Activity Reporter), which features superior sensitivity, kinetics, and tractability for high throughput screening. Using this tool, we carried a drug repurposing screen (4,475 compounds in clinical use) in human cells expressing autonomously active CaMKII. This yielded five previously unrecognized CaMKII inhibitors with clinically relevant potency: ruxolitinib, baricitinib, silmitasertib, crenolanib, and abemaciclib. Standout among these, ruxolitinib, an orally bioavailable and U.S Food and Drug Administration (FDA)-approved medication, inhibited CaMKII in cultured cardiomyocytes and in mice at concentrations equivalent to human doses. 10-minute treatment in mice was sufficient to prevent atrial fibrillation--the most common clinical arrhythmia. At cardioprotective doses, ruxolitinib-treated mice behaved normally in established cognitive assays. Our results suggest that human CaMKII inhibition is feasible and safe, and support prompt clinical investigation of ruxolitinib for cardiac indications.

Dysregulation of N-terminal acetylation causes cardiac arrhythmia and cardiomyopathy

“…iPSC disease modeling has dramatically shortened the arc of therapeutic translation. The repurposing of already approved drugs 42 and development of targeted gene therapies are just two therapeutic development pathways that have bene ted from iPSC modeling of cardiac disorders 50 . To determine if NAA10-related syndrome would be amenable to targeted gene therapy, we developed an adenovirus vector to over-express WT NAA10 in the NAA10-mutant iPSC-CMs.…”