ABSTRACT
Cardiomyocyte loss after injury results in adverse remodelling and fibrosis, inevitably leading to heart failure. The ERBB2-Neuregulin and Hippo-YAP signalling pathways are key mediators of heart regeneration, yet the crosstalk between them is unclear. We demonstrate that transient overexpression of activated ERBB2 in cardiomyocytes (OE CMs) promotes cardiac regeneration in a heart failure model. OE CMs present an epithelial-mesenchymal transition (EMT)-like regenerative response manifested by cytoskeletal remodelling, junction dissolution, migration and extracellular matrix turnover. We identified YAP as a critical mediator of ERBB2 signalling. In OE CMs, YAP interacts with nuclear-envelope and cytoskeletal components, reflecting an altered mechanical state elicited by ERBB2. We identified two YAP-activating phosphorylations on S352 and S274 in OE CMs, which peak during metaphase, that are ERK dependent and Hippo independent. Viral overexpression of YAP phospho-mutants dampened the proliferative competence of OE CMs. Together, we reveal a potent ERBB2-mediated YAP mechanotransduction signalling, involving EMT-like characteristics, resulting in robust heart regeneration.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Cell Cycle Proteins/metabolism , Cell Proliferation , Epithelial-Mesenchymal Transition , Heart Failure/metabolism , Myocardial Infarction/metabolism , Myocytes, Cardiac/metabolism , Receptor, ErbB-2/metabolism , Regeneration , Adaptor Proteins, Signal Transducing/genetics , Animals , Cell Cycle Proteins/genetics , Cells, Cultured , Cytoskeleton/metabolism , Cytoskeleton/pathology , Disease Models, Animal , Extracellular Signal-Regulated MAP Kinases/metabolism , Fibrosis , Heart Failure/genetics , Heart Failure/pathology , Heart Failure/physiopathology , Mechanotransduction, Cellular , Mice, Transgenic , Myocardial Infarction/genetics , Myocardial Infarction/pathology , Myocardial Infarction/physiopathology , Myocytes, Cardiac/pathology , Phosphorylation , Receptor, ErbB-2/genetics , YAP-Signaling ProteinsABSTRACT
The adult mammalian heart regenerates poorly after injury and, as a result, ischemic heart diseases are among the leading causes of death worldwide. The recovery of the injured heart is dependent on orchestrated repair processes including inflammation, fibrosis, cardiomyocyte survival, proliferation, and contraction properties that could be modulated in patients. In this work we designed an automated high-throughput screening system for small molecules that induce cardiomyocyte proliferation in vitro and identified the small molecule Chicago Sky Blue 6B (CSB). Following induced myocardial infarction, CSB treatment reduced scar size and improved heart function of adult mice. Mechanistically, we show that although initially identified using in vitro screening for cardiomyocyte proliferation, in the adult mouse CSB promotes heart repair through (i) inhibition of CaMKII signaling, which improves cardiomyocyte contractility; and (ii) inhibition of neutrophil and macrophage activation, which attenuates the acute inflammatory response, thereby contributing to reduced scarring. In summary, we identified CSB as a potential therapeutic agent that enhances cardiac repair and function by suppressing postinjury detrimental processes, with no evidence for cardiomyocyte renewal.
