Inhibition of Mas G-protein signaling improves coronary blood flow, reduces myocardial infarct size, and provides long-term cardioprotection

Am J Physiol Heart Circ Physiol. 2012 Jan 1;302(1):H299-311. doi: 10.1152/ajpheart.00723.2011. Epub 2011 Oct 14.


The Mas receptor is a class I G-protein-coupled receptor that is expressed in brain, testis, heart, and kidney. The intracellular signaling pathways activated downstream of Mas are still largely unknown. In the present study, we examined the expression pattern and signaling of Mas in the heart and assessed the participation of Mas in cardiac ischemia-reperfusion injury. Mas mRNA and protein were present in all chambers of human hearts, with cardiomyocytes and coronary arteries being sites of enriched expression. Expression of Mas in either HEK293 cells or cardiac myocytes resulted in constitutive coupling to the G(q) protein, which in turn activated phospholipase C and caused inositol phosphate accumulation. To generate chemical tools for use in probing the function of Mas, we performed a library screen and chemistry optimization program to identify potent and selective nonpeptide agonists and inverse agonists. Mas agonists activated G(q) signaling in a dose-dependent manner and reduced coronary blood flow in isolated mouse and rat hearts. Conversely, treatment of isolated rat hearts with Mas inverse agonists improved coronary flow, reduced arrhythmias, and provided cardioprotection from ischemia-reperfusion injury, an effect that was due, at least in part, to decreased cardiomyocyte apoptosis. Participation of Mas in ischemia-reperfusion injury was confirmed in Mas knockout mice, which had reduced infarct size relative to mice with normal Mas expression. These results suggest that activation of Mas during myocardial infarction contributes to ischemia-reperfusion injury and further suggest that inhibition of Mas-G(q) signaling may provide a new therapeutic strategy directed at cardioprotection.

MeSH terms

  • Animals
  • Animals, Newborn
  • Apoptosis / drug effects
  • Cardiotonic Agents / chemistry
  • Cardiotonic Agents / pharmacology*
  • Coronary Circulation / drug effects*
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Drug Inverse Agonism
  • Enzyme Activation
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism*
  • HEK293 Cells
  • Humans
  • Inositol Phosphates / metabolism
  • Mice
  • Mice, Knockout
  • Molecular Structure
  • Myocardial Infarction / genetics
  • Myocardial Infarction / metabolism
  • Myocardial Infarction / pathology
  • Myocardial Infarction / physiopathology
  • Myocardial Infarction / prevention & control*
  • Myocardial Reperfusion Injury / genetics
  • Myocardial Reperfusion Injury / metabolism
  • Myocardial Reperfusion Injury / pathology
  • Myocardial Reperfusion Injury / physiopathology
  • Myocardial Reperfusion Injury / prevention & control*
  • Myocardium / metabolism*
  • Myocardium / pathology
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins / antagonists & inhibitors*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, G-Protein-Coupled / antagonists & inhibitors*
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Signal Transduction / drug effects*
  • Time Factors
  • Transfection
  • Type C Phospholipases / metabolism
  • Ventricular Function, Left / drug effects


  • Cardiotonic Agents
  • Inositol Phosphates
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Receptors, G-Protein-Coupled
  • Type C Phospholipases
  • GTP-Binding Protein alpha Subunits, Gq-G11