Post-translational modifications of cardiac myosin-binding protein-C: Mechanisms behind fine-tuning the sarcomere

Since the discovery of the cardiac isoform of myosin-binding protein-C (cMyBP-C), there has been continued interest in how cMyBP-C impacts cardiac function in both health and disease. cMyBP-C is a regulatory protein in the sarcomere that controls beat-to-beat changes in contractility in response to dynamic environmental demands placed upon the heart. Changes in force production during the contractile cycle are modulated through interactions of cMyBP-C with myosin and actin. Post-translational modifications (PTMs) of cMyBP-C, of which phosphorylation has received the most attention, are critical to the function of cMyBP-C in the healthy heart and is affected in many disease states. While each of the PTMs that will be discussed in this review have known and often widespread effects on important cellular processes spanning transcriptional regulation, cell signaling, and metabolism, their impact on cMyBP-C function remains poorly understood and in some cases unverified. This Review focuses on the current understanding of cMyBP-C PTMs, namely phosphorylation, S-glutathionylation, S-nitrosylation, acetylation, citrullination, carbonylation, and O-GlcNAcylation. The potential for PTMs to exert wide ranging and likely nuanced effects may influence the range of cMyBP-C's response to varied conditions and may offer opportunities to identify novel therapeutic paradigms in the setting of disease.