Acetylation of muscle creatine kinase negatively impacts high-energy phosphotransfer in heart failure.

Matthew A Walker,Outi Villet,Juan Chavez,Andrew Keller,Rong Tian,James E Bruce,Xiaoting Tang

doi:10.1172/jci.insight.144301

Abstract

A hallmark of impaired myocardial energetics in failing hearts is the downregulation of the creatine kinase (CK) system. In heart failure patients and animal models, myocardial phosphocreatine content and the flux of the CK reaction are negatively correlated with the outcome of heart failure. While decreased CK activity is highly reproducible in failing hearts, the underlying mechanisms remains elusive. Here, we report an inverse relationship between the activity and acetylation of CK muscle form (CKM) in human and mouse failing hearts. Hyperacetylation of recombinant CKM disrupted MM homodimer formation and reduced enzymatic activity, which could be reversed by sirtuin 2 treatment. Mass spectrometry analysis identified multiple lysine residues on the MM dimer interface, which were hyperacetylated in the failing hearts. Molecular modeling of CK MM homodimer suggested that hyperacetylation prevented dimer formation through interfering salt bridges within and between the 2 monomers. Deacetylation by sirtuin 2 reduced acetylation of the critical lysine residues, improved dimer formation, and restored CKM activity from failing heart tissue. These findings reveal a potentially novel mechanism in the regulation of CK activity and provide a potential target for improving high-energy phosphoryl transfer in heart failure.

Highlights

A hallmark of impaired energetics in the human failing heart is decreased creatine kinase (CK) activity [1,2,3,4]
We determined the relationship between CK activity and its protein level in human failing hearts due to ischemic or dilated cardiomyopathy (Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/ jci.insight.144301DS1) and in a mouse model of heart failure induced by transverse aortic constriction (TAC) for 12 weeks (Supplemental Figure 1, A–C)
We propose that acetylation of CK isoform (CKM) during the development of heart failure decreased its enzymatic activity and, negatively impacts phosphotransfer via the CK reaction in failing hearts

Summary

Introduction

A hallmark of impaired energetics in the human failing heart is decreased creatine kinase (CK) activity [1,2,3,4]. Distinct genes encode M and B isoforms of CK that form stable homo and hetero dimers (MM, MB, BB) in cytosol [6]. In their native state, cytosolic isozymes are stable dimers facilitating high-energy phosphate transfer from mitochondria to sites of ATP utilization. A third gene encodes mitochondrial isoform of the CK (MtCK) that forms both dimers and octamers, depending on pH and concentration. Through unknown mechanisms, decreased CK activity is highly reproducible in the failing hearts of all experimental and clinical studies, and it results in reductions in ATP delivery to the myofibrils by up to 71% [9]. Overexpression of CKM in mouse hearts preserves ATP production via the CK reaction and improves survival and contractile function in pressure overload–induced heart failure [8]

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Results

Conclusion