Regulation of the Balance between Concentric and Eccentric Cardiac Hypertrophy by a CDC14A-KMT5A Signaling Pathway

Depending upon the type of pathological stress, the heart undergoes concentric or eccentric remodeling. This structural change is associated with diastolic and/or systolic ventricular dysfunction reflecting differentially altered cardiomyocyte morphology, ultrastructure, metabolism, contractility, and survival, as well as interstitial myocardial fibrosis. Despite an association of both concentric and eccentric remodeling with heart failure and sudden death, the molecular mechanisms resulting in abnormal cardiac geometry remain poorly understood. A better understanding of the basic mechanisms conferring these contrasting forms of remodeling should inform novel approaches to preserve normal cardiac structure and function in cardiovascular disease. The protein phosphatase Cell Division Cycle 14A (CDC14A) and its substrate the lysine methyltransferase KMT5A are identified herein as key regulators of the balance between concentric and eccentric pathological cardiac remodeling.

The regulation of adult rat ventricular myocyte morphology by CDC14A and KMT5A was studied in vitro following gain and loss of function by expression of wild-type and mutant proteins and RNA interference (RNAi). Epigenomic regulation by KMT5A was studied by mapping histone 4 lysine 20 mono-methylation (H4K20me1) modified chromatin sites and correlating them with gene transcription. Regulation of pathological cardiac remodeling in vivo was demonstrated by CDC14A and KMT5A RNAi using adeno-associated virus (AAV) mediated cardiomyocyte-specific small hairpin RNA (shRNA) expression in mice.

CDC14A inhibited the growth in width of cultured adult myocytes stimulated by α-adrenergic receptor activation or by serum response factor. KMT5A was downregulated by CDC14A in cardiomyocytes and was required for myocyte growth in width. α-adrenergic stimulation of KMT5A-dependent H4K20 mono-methylation across transcription units correlated with regulation of gene transcription. Accordingly, AAV-expressed KMT5A shRNA induced eccentric remodeling and cardiac dysfunction in wild-type mice. Conversely, expression of Cdc14A shRNA improved systolic function and cardiac structure and inhibited pathological gene expression in the Tpm1 E54K mouse with Dilated Cardiomyopathy.

CDC14A-KMT5A-dependent epigenomic regulation of gene transcription constitutes a molecular switch that determines concentric versus eccentric cardiac remodeling. These findings identify CDC14A as a potential therapeutic target for the treatment of dilated cardiomyopathy and other forms of heart failure with reduced ejection fraction.

What is new: A function is identified for the first time for the protein phosphatase CDC14A in the heart, regulation of cardiomyocyte morphology and overall cardiac geometry in pathological cardiac remodeling.The lysine methyltransferase KMT5A is shown to mediate the effects of CDC14A in the adult cardiomyocyte by regulating H4K20 mono-methylation, such that reduced KMT5A expression promotes a phenotype resembling Dilated Cardiomyopathy.H4K20me1 epigenomic modification is identified as a regulator of cardiac structure and function.Clinical implications: CDC14A loss of function experimentation in vivo , resulting in improved cardiac structure and function in a mouse model of Dilated Cardiomyopathy, suggests that CDC14A is a novel therapeutic target for heart failure with reduced ejection fraction.