Protection of cardiomyocytes from the hypoxia-mediated injury by a peptide targeting the activator of G-protein signaling 8

PLoS One. 2014 Mar 14;9(3):e91980. doi: 10.1371/journal.pone.0091980. eCollection 2014.

Abstract

Signaling via heterotrimeric G-protein is involved in the development of human diseases including ischemia-reperfusion injury of the heart. We previously identified an ischemia-inducible G-protein activator, activator of G-protein signaling 8 (AGS8), which regulates Gβγ signaling and plays a key role in the hypoxia-induced apoptosis of cardiomyocytes. Here, we attempted to intervene in the AGS8-Gβγ signaling process and protect cardiomyocytes from hypoxia-induced apoptosis with a peptide that disrupted the AGS8-Gβγ interaction. Synthesized AGS8-peptides, with amino acid sequences based on those of the Gβγ-binding domain of AGS8, successfully inhibited the association of AGS8 with Gβγ. The AGS8-peptide effectively blocked hypoxia-induced apoptosis of cardiomyocytes, as determined by DNA end-labeling and an increase in cleaved caspase-3. AGS8-peptide also inhibited the change in localization/permeability of channel protein connexin 43, which was mediated by AGS8-Gβγ under hypoxia. Small compounds that inhibit a wide range of Gβγ signals caused deleterious effects in cardiomyocytes. In contrast, AGS8-peptide did not cause cell damage under normoxia, suggesting an advantage inherent in targeted disruption of the AGS8-Gβγ signaling pathway. These data indicate a pivotal role for the interaction of AGS8 with Gβγ in hypoxia-induced apoptosis of cardiomyocytes, and suggest that targeted disruption of the AGS8-Gβγ signal provides a novel approach for protecting the myocardium against ischemic injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cell Hypoxia / drug effects
  • Connexin 43 / metabolism
  • Cytoprotection / drug effects*
  • GTP-Binding Protein gamma Subunits / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / chemistry
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Myocardial Ischemia / prevention & control
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / metabolism
  • Peptides / pharmacology*
  • Permeability / drug effects
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Rats
  • Rats, Wistar
  • Signal Transduction / drug effects

Substances

  • Connexin 43
  • Fndc1 protein, rat
  • GTP-Binding Protein gamma Subunits
  • Intracellular Signaling Peptides and Proteins
  • Peptides

Grant support

This work is supported by Grant-in-Aid for Scientific Research on Innovative Areas of Japan (MS), Grant-in-Aid for Scientific Research of Japan (MS), the Toyoaki Scholarship Foundation (MS), The Naito Foundation (MS) and Strategic Research Foundation Grant-aided Project for Private Universities from the Ministry of Education, Culture, Sports, Science, and Technology, Japan (MEXT), 2011–2015 (S1101027). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.