Theranostics 2018; 8(17):4664-4678. doi:10.7150/thno.26619
Pepducin-mediated cardioprotection via β-arrestin-biased β2-adrenergic receptor-specific signaling
1. Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA
2. Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
3. Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
Grisanti LA, Thomas TP, Carter RL, de Lucia C, Gao E, Koch WJ, Benovic JL, Tilley DG. Pepducin-mediated cardioprotection via β-arrestin-biased β2-adrenergic receptor-specific signaling. Theranostics 2018; 8(17):4664-4678. doi:10.7150/thno.26619. Available from https://www.thno.org/v08p4664.htm
Reperfusion as a therapeutic intervention for acute myocardial infarction-induced cardiac injury itself induces further cardiomyocyte death. β-arrestin (βarr)-biased β-adrenergic receptor (βAR) activation promotes survival signaling responses in vitro; thus, we hypothesize that this pathway can mitigate cardiomyocyte death at the time of reperfusion to better preserve function. However, a lack of efficacious βarr-biased orthosteric small molecules has prevented investigation into whether this pathway relays protection against ischemic injury in vivo. We recently demonstrated that the pepducin ICL1-9, a small lipidated peptide fragment designed from the first intracellular loop of β2AR, allosterically engaged pro-survival signaling cascades in a βarr-dependent manner in vitro. Thus, in this study we tested whether ICL1-9 relays cardioprotection against ischemia/reperfusion (I/R)-induced injury in vivo.
Methods: Wild-type (WT) C57BL/6, β2AR knockout (KO), βarr1KO and βarr2KO mice received intracardiac injections of either ICL1-9 or a scrambled control pepducin (Scr) at the time of ischemia (30 min) followed by reperfusion for either 24 h, to assess infarct size and cardiomyocyte death, or 4 weeks, to monitor the impact of ICL1-9 on long-term cardiac structure and function. Neonatal rat ventricular myocytes (NRVM) were used to assess the impact of ICL1-9 versus Scr pepducin on cardiomyocyte survival and mitochondrial superoxide formation in response to either serum deprivation or hypoxia/reoxygenation (H/R) in vitro and to investigate the associated mechanism(s).
Results: Intramyocardial injection of ICL1-9 at the time of I/R reduced infarct size, cardiomyocyte death and improved cardiac function in a β2AR- and βarr-dependent manner, which led to improved contractile function early and less fibrotic remodeling over time. Mechanistically, ICL1-9 attenuated mitochondrial superoxide production and promoted cardiomyocyte survival in a RhoA/ROCK-dependent manner. RhoA activation could be detected in cardiomyocytes and whole heart up to 24 h post-treatment, demonstrating the stability of ICL1-9 effects on βarr-dependent β2AR signaling.
Conclusion: Pepducin-based allosteric modulation of βarr-dependent β2AR signaling represents a novel therapeutic approach to reduce reperfusion-induced cardiac injury and relay long-term cardiac remodeling benefits.
Keywords: Pepducin, β-arrestin, β2-adrenergic receptor, cardiac ischemia/reperfusion, cardiomyocyte