Protein phosphatase 1-disrupting peptides: Scope and mechanism of action in the treatment of heart insufficiency

ongoing

Protein phosphatase-1 (PP1) is a ubiquitously expressed enzyme known to dephosphorylate a large number of the phosphorylated serines and threonines. The catalytic subunit PP1c is bound to regulatory proteins in holoenzymes. These play specific and fundamental roles in physiological processes and pathologies. One key role lies in the regulation of important cardiac signaling pathways and calcium homoeostasis. Accordingly, deregulation of PP1 has been implicated in cardiac dysfunctions. Powerful tools to study PP1 biology are our own developed PP1-disrupting peptides (PDPs) that selectively release PP1c (bound to PDP: PDP–PP1c) activity in cells. Recently, we showed that PDP treatment counteracts kinase hyperactivity and seals the arrhythmogenic sarcoplasmic reticulum (SR)-calcium-leak in human heart failure tissue. Mechanistic data indicated that PDP–PP1c-mediated dephosphorylation of the ryanodine receptor type 2 (RyR2) is involved in this effect. Nevertheless, given the large amount of potential PP1 substrates, so far the scope of PDP action is unknown, and therefore the mechanisms underlying this beneficial and potentially therapeutic effect of the PDPs in heart failure are unclear and currently hard to investigate. PDPcardio will address these challenges by providing new chemical biology methodologies combined with proteomics approaches using PDPs to guide PP1c to its substrates and to identify PDP-mediated interactions of PP1. These strategies will enable identifying the scope of PDP action in general, and in particular they will be applied here in cardiomyocytes to study the effects of PDP–PP1c. The results will provide the basis to fine-tune targeting PP1 for the treatment of heart insufficiency. Furthermore, the principles and methods developed here will be applicable more generally for defining the interaction scope of target-bound ligands (drugs) as well as for using PP1 as tool in synthetic biology.