Oxidative Stress Induces Monocyte Necrosis with Enrichment of Cell-Bound Albumin and Overexpression of Endoplasmic Reticulum and Mitochondrial Chaperones

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.

Hydrogen peroxide mediated mitochondrial UNG1-PRDX3 interaction and UNG1 degradation

“…In order to determine binding partners of UNG1, we established an UNG1-overexpressing cell line in the present work. Overexpression of UNG1 in A549 cells did not lead to visible changes in cell morphology or growth rates whereas it did enhance cell resistance to oxidative stress induced by hydrogen peroxide or gossypol that was also an oxidant [28,29]. The results presented in Fig.…”

A genetic variant in SLC30A2 causes breast dysfunction during lactation by inducing ER stress, oxidative stress and epithelial barrier defects

“…This provides evidence that expression of the S 288 variant is associated with oxidative stress and dysfunction in the breast during lactation. To confirm this, we measured several key oxidative stress markers; 4-hydroxynonenal (4-HNE), a product of lipid peroxidation 42 , mucin-4, an adhesive glycoprotein that is upregulated in response to oxidative stress 43 , and endoplasmin, an ER-specific chaperone that increases in response to ER and oxidative stress 44 . We found that 4-HNE, mucin-4 and endoplasmin were all significantly higher in the breastmilk of women harboring S 288 compared with women harboring two wild-type alleles (Fig.…”

Proinsulin and heat shock protein 90 as biomarkers of beta-cell stress in the early period after onset of type 1 diabetes

“…31 In addition, studies indicate that oxidative stress can promote measurable cellular release of HSP90. 32 Notably, alterations in autoantibody responses to HSP90 have been reported in patients with T1D. 33 Given the association with ER and oxidative stress, HSP90 is therefore a plausible candidate for a serum marker of β -cell stress.…”