Endothelin‐1 receptor antagonists regulate cell surface‐associated protein disulfide isomerase in sickle cell disease

Abstract

Increased endothelin-1 (ET-1) levels, disordered thiol protein status, and erythrocyte hydration status play important roles in sickle cell disease (SCD) through unresolved mechanisms. Protein disulfide isomerase (PDI) is an oxidoreductase that mediates thiol/disulfide interchange reactions. We provide evidence that PDI is present in human and mouse erythrocyte membranes and that selective blockade with monoclonal antibodies against PDI leads to reduced Gardos channel activity (1.6±0.03 to 0.56±0.02 mmol·10(13) cell(-1)·min(-1), P<0.001) and density of sickle erythrocytes (D50: 1.115±0.001 to 1.104±0.001 g/ml, P=0.012) with an IC50 of 4 ng/ml. We observed that erythrocyte associated-PDI activity was increased in the presence of ET-1 (3.1±0.2 to 5.6±0.4%, P<0.0001) through a mechanism that includes casein kinase II. Consistent with these results, in vivo treatment of BERK sickle transgenic mice with ET-1 receptor antagonists lowered circulating and erythrocyte associated-PDI activity (7.1±0.3 to 5.2±0.2%, P<0.0001) while improving hematological parameters and Gardos channel activity. Thus, our results suggest that PDI is a novel target in SCD that regulates erythrocyte volume and oxidative stress and may contribute to cellular adhesion and endothelial activation leading to vasoocclusion as observed in SCD.

Targeting protein disulfide isomerase with the flavonoid isoquercetin to improve hypercoagulability in advanced cancer

“…These data suggest that P selectin-mediated thrombosis plays a central role in the hypercoagulability of cancer and further support the clinical development of isoquercetin specifically for the indication of cancer-associated thrombosis. Sickle cell disease is another potential indication that merits investigation, considering the emerging data that targeting P selectin with a monoclonal antibody reduces painful crises (48,49).…”

Aldosterone's Rapid, Nongenomic Effects Are Mediated by Striatin: A Modulator of Aldosterone's Effect on Estrogen Action

“…Mouse aortic ECs were isolated from male mice under sterile conditions as previously described (7,15,16) and maintained on DMEM (see Supplemental Materials for details). Our cell cultures showed positive staining for EC markers, because they were positive for Von Willebrand factor and platelet-endothelial cell adhesion molecule-1 (CD31) using immunofluorescence techniques (Supplemental Figure 1).…”

Native structure of the RhopH complex, a key determinant of malaria parasite nutrient acquisition

“…As such, it is possible that these bonds may break or be cleaved upon interaction with the erythrocyte membrane, triggering a conformation change that extrudes the putative transmembrane and extracellular elements from the middle of the complex and drives them through membrane. While no parasite-derived protein disulfide isomerases (PDIs) have been identified in the P. falciparum exportome, human erythrocytes do carry active PDIs in the plasma membrane 38,39 , which could cleave the allosteric disulfides and trigger the conformational change upon coming in contact with the RhopH complex at the membrane. Alternatively, different redox potential in the cytosol could trigger the breakage of the disulfide bonds to effect the massive conformational changes needed to expose and bring the above-described helical bundle of CLAG3 to interact with red blood cell membrane (Fig.…”