Cardiac myocyte exosomes: Stability, HSP60, and proteomics

Z. A. Malik, K. S. Kott, A. J. Poe, T. Kuo, L. Chen, K. W. Ferrara, Anne A Knowlton

Research output: Contribution to journalArticle

106 Scopus citations

Abstract

Exosomes, which are 50- to 100-nm-diameter lipid vesicles, have been implicated in intercellular communication, including transmitting malignancy, and as a way for viral particles to evade detection while spreading to new cells. Previously, we demonstrated that adult cardiac myocytes release heat shock protein (HSP)60 in exosomes. Extracellular HSP60, when not in exosomes, causes cardiac myocyte apoptosis via the activation of Toll-like receptor 4. Thus, release of HSP60 from exosomes would be damaging to the surrounding cardiac myocytes. We hypothesized that 1) pathological changes in the environment, such as fever, change in pH, or ethanol consumption, would increase exosome permeability; 2) different exosome inducers would result in different exosomal protein content; 3) ethanol at "physiological" concentrations would cause exosome release; and 4) ROS production is an underlying mechanism of increased exosome production. We found the following: first, exosomes retained their protein cargo under different physiological/pathological conditions, based on Western blot analyses. Second, mass spectrometry demonstrated that the protein content of cardiac exosomes differed significantly from other types of exosomes in the literature and contained cytosolic, sarcomeric, and mitochondrial proteins. Third, ethanol did not affect exosome stability but greatly increased the production of exosomes by cardiac myocytes. Fourth, ethanol- and hypoxia/reoxygenation-derived exosomes had different protein content. Finally, ROS inhibition reduced exosome production but did not completely inhibit it. In conclusion, exosomal protein content is influenced by the cell source and stimulus for exosome formation. ROS stimulate exosome production. The functions of exosomes remain to be fully elucidated.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume304
Issue number7
DOIs
StatePublished - 2013

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Keywords

  • Alcoholic cardiomyopathy
  • Ethanol
  • Exosome
  • Heat shock protein 60
  • Proteomics
  • Reactive oxygen species
  • Valosin-containing protein

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

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