Oxidative stress induces monocyte necrosis with enrichment of cell-bound albumin and overexpression of endoplasmic reticulum and mitochondrial chaperones

PLoS One. 2013;8(3):e59610. doi: 10.1371/journal.pone.0059610. Epub 2013 Mar 26.

Abstract

In the present study, monocytes were treated with 5-azacytidine (azacytidine), gossypol or hydrogen peroxide to induce cell death through oxidative stress. A shift from apoptotic to necrotic cell death occurred when monocytes were treated with 100 µM azacytidine for more than 12 hours. Necrotic monocytes exhibited characteristics, including enrichment of cell-bound albumin and up-regulation of endoplasmic reticulum (ER)- and mitochondrial-specific chaperones to protect mitochondrial integrity, which were not observed in other necrotic cells, including HUH-7, A2780, A549 and HOC1a. Our results show that the cell-bound albumin originates in the culture medium rather than from monocyte-derived hepatocytes, and that HSP60 is a potential binding partner of the cell-bound albumin. Proteomic analysis shows that HSP60 and protein disulfide isomerase are the most abundant up-regulated mitochondrial and ER-chaperones, and that both HSP60 and calreticulin are ubiquitinated in necrotic monocytes. In contrast, expression levels of the cytosolic chaperones HSP90 and HSP71 were down-regulated in the azacytidine-treated monocytes, concomitant with an increase in the levels of these chaperones in the cell culture medium. Collectively, our results demonstrates that chaperones from different organelles behave differently in necrotic monocytes, ER- and mitochondrial chaperones being retained and cytosolic and nuclear chaperones being released into the cell culture medium through the ruptured cell membrane. HSP60 may serve as a new target for development of myeloid leukemia treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis / drug effects
  • Azacitidine / pharmacology
  • Cattle
  • Cell Line
  • Culture Media / chemistry
  • Endoplasmic Reticulum / drug effects*
  • Gene Expression Regulation / drug effects
  • Gossypol / pharmacology
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Molecular Chaperones / chemistry
  • Molecular Chaperones / metabolism*
  • Molecular Sequence Data
  • Monocytes / drug effects
  • Monocytes / metabolism
  • Monocytes / pathology*
  • Necrosis / chemically induced*
  • Oxidative Stress / drug effects*
  • Proteomics
  • Serum Albumin, Bovine / metabolism*
  • Ubiquitination / drug effects

Substances

  • Culture Media
  • Molecular Chaperones
  • Serum Albumin, Bovine
  • Hydrogen Peroxide
  • Gossypol
  • Azacitidine

Grant support

This work was supported in part by the Center for Life Sciences (Tsinghua University), the National Natural Science Foundation of China (No.30872391). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.