Activation of the Mineralocorticoid Receptor Stimulates Protein Disulfide Isomerase: Role in Sickle Cell Disease

Abstract Activation of the mineralocorticoid receptor (MR), a critical component of the Renin-Angiotensin-Aldosterone (ALDO)-System (RAAS), has been shown to play an important role in inflammatory and vascular endothelial responses in addition to its well-described effects on sodium and water homeostasis. Activationof endothelial cells leads to, among other factors, increased endothelin-1 (ET-1) and protein disulfide isomerase (PDI) release. PDI and ET-1 contribute to vascular inflammation and are increased in patients with SCD and sickle transgenic mouse models. The MR is a member of the steroid family of nuclear receptors and transcription factors that upon activation binds to hormone response elements of edn1, the gene for ET-1, leading to increased ET-1 expression.In vivo, blockade of MR has been shown to reduce circulating ET-1 levels and ET-1 mRNA expression. However, the role of MR in SCD is unclear. We hypothesized that MR blockade in sickle transgenic mice would reduce PDI activity and improve hematological parameters and inflammation. We first studied EA.hy926 (EA) cells, a human endothelial cell line that expresses MR. We incubated EA cells with ALDO (10-8 M), an MR agonist, for 24 hr and observed a rise in PDI mRNA levels by qRT-PCR (P<0.01, n=5), an event that was blocked by pre-incubation of EA cells with 1 μM canrenoic acid (CA), an MR antagonist (P<0.05, n=5). We then measured PDI activity in the supernatant of ALDO-stimulated EA cells using a Di-E-GSSH fluorescent marker and observed a rise in PDI activity following ALDO (10-8 M) when compared to vehicle treatment (P<0.05; n=5). To test the in vivo effects of MR activation, we studied Berkeley Sickle Transgenic (BERK) mice that were randomized to receive either normal rodent chow or chow containing eplerenone (156 mg/kg per day), an MR antagonist (MRA), for 14 days. We observed significantly lower plasma PDI activity in mice treated with MRA than those on regular chow (63.7 ± 8.7 control diet to 47.9 ± 2.4 eplerenone, Relative Fluorescence Units (RFU); P<0.005, n=6 and 9, respectively). Treatment with MRA was associated with reduced plasma ET-1 and myeloperoxidase (MPO) levels in BERK mice. We also studied RBC Gardos channel activity in these mice and observed a significant reduction in clotrimazole-sensitive K+ efflux following MR blockade (2.49±0.5 control and 1.37±0.3 mmol/1013 cells x hr; P<0.04 n= 5 and 7 respectively). Consistent with these results, MR blockade was associated with increases in both erythrocyte MCV (41.3±2.5 vs 47.4±1.1 fL, P<0.03, n=7) and reticulocyte MCV (53.6.3±2.8 vs 60.1±0.6 fL, P<0.02, n=7). We also studied gene expression by qRT-PCR in heart tissue from these mice and observed that MR blockade reduced mRNA expression of: ET-1 (0.654 ± 0.233, P<0.05, n=5 and n=7); PDI (0.546 ± 0.063, P<0.01, n=5 and n=7); and Tumor Necrosis Factor Receptor Superfamily Member 1A mRNA (0.464 ± 0.061, P<0.01, n=5 and n=7). Thus, our results suggest a novel role for RAAS and, in particular, MR activation in SCD. Disclosures No relevant conflicts of interest to declare.

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Blockade of the Mineralocorticoid Receptor in Sickle Transgenic Mice Reduces Circulating Protein Disulfide Isomerase and Gardos Channel Activity

Blood ◽

10.1182/blood.v120.21.999.999 ◽

2012 ◽

Vol 120 (21) ◽

pp. 999-999

Author(s):

Christopher Vega ◽

Gregory N. Prado ◽

Philip Asamoah ◽

Patricia Neuman ◽

Jose R Romero ◽

...

Keyword(s):

Endothelial Cells ◽

Transgenic Mice ◽

Protein Disulfide Isomerase ◽

Mineralocorticoid Receptor ◽

Hematological Parameters ◽

Channel Activity ◽

Cell Disease ◽

Disulfide Isomerase ◽

Gardos Channel ◽

Protein Disulfide

Abstract Abstract 999 Endothelin-1 (ET-1), erythrocyte sickling and endothelial cell activation have been proposed as important contributors to the pathophysiology of sickle cell disease (SCD). We have provided evidence for the use of ET-1 receptor antagonists in improving hematological parameters in two transgenic mouse models of SCD (Rivera A., 2008, Amer J Physiol). However, the mechanisms that mediate the interplay between red blood cells (RBC) and the endothelium in SCD remain unresolved. Activation of endothelial cells leads to, among other factors, increased levels of protein disulfide isomerase (PDI). PDI catalyzes disulfide interchange reactions, mediates redox modifications and has been observed to be up-regulated under hypoxic conditions. We now report that circulating PDI activity is increased in BERK sickle transgenic mice when compared to wild-type controls. The mineralocorticoid receptor (MR) is a member of the steroid family of nuclear receptors that function as a transcription factor that upon binding to the hormone responsive element of genes such as edn1, the gene for ET-1, leads to increased ET-1 expression. In vivo, blockade of MR has been shown to reduce circulating ET-1 levels and kidney ET-1 mRNA expression. We hypothesized that MR blockade of BERK sickle transgenic mice would lead to reduced PDI activity and improved hematological parameters. Sickle mice were randomized to receive either normal rodent chow or chow containing eplerenone (156 mg/kg per day), an MR receptor antagonist, and tap water ad libitum for 14 days at which time the mice were sacrificed and tissues and blood collected. Plasma PDI activity was calculated by optimization of fluorescently labeled GSSG conversion to GSH. We observed that mice on eplerenone had significantly lower plasma PDI activity than mice on regular chow (63.7 ± 8.7 control diet to 47.9 ± 2.4 eplerenone, Relative Fluorescence Units; P<0.005, n=6 and 9, respectively). We also studied RBC Gardos channel activity in these mice and observed a significant reduction in clotrimazole-sensitive K+ efflux following MR blockade (2.49±0.5 control and 1.37±0.3 mmol/1013 cells × hr; P<0.04 n= 5 and 7 respectively). MR blockade was associated with increases in both erythrocyte MCV (41.3±2.5 vs 47.4±1.1 fL, P<0.03, n=7) and reticulocyte MCV (53.6.3±2.8 vs 60.1±0.6 fL, P<0.02, n=7) as determined by an ADVIA 120 hematology analyzer. In contrast no significant effects on MCHC levels were observed under these conditions. We then studied ET-1 gene expression using quantitative RT-PCR with ABI Taqman chemistries and GAPDH and β-actin as endogenous controls. We observed that MR blockade was associated with reduced expression of ET-1 mRNA in heart tissue (0.654 ± 0.233, ΔΔCT, relative to mice on regular chow, P<0.04, n=5 and n=7) but not lung tissue. Western blot analyses in membranes from human and mouse sickle erythrocytes and endothelial cells revealed the presence of both MR and PDI proteins. We then studied the effects of ET-1 in early cultures of BERK mouse aortic endothelial cells (MAEC). We observed that stimulation of MAEC cells with 100nM ET-1 for 4 hr was associated with increased mRNA expression of PDI levels that was 1.71 fold greater than vehicle treated cells (n=4, P<0.05). Thus, our results suggest that MR blockade reduces ET-1 levels leading to reduced Gardos and PDI activity in Sickle mice. These effects on PDI activity and Gardos channel regulation may represent a novel mechanism for protective effects of MR blockade aimed at ameliorating vascular complications of Sickle Cell Disease. Supported by NIH R01HL090632 to AR. Disclosures: No relevant conflicts of interest to declare.

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Aldosterone Stimulates a Degranulation Response in Human Neutrophils: Role of Protein Disulfide Isomerase

Blood ◽

10.1182/blood.v120.21.1034.1034 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1034-1034

Author(s):

Daphne Diaz ◽

Gregory N. Prado ◽

Patricia Neuman ◽

Adriana Nieva ◽

Manuel Torres-Grajales ◽

...

Keyword(s):

Western Blot ◽

Protein Disulfide Isomerase ◽

Mineralocorticoid Receptor ◽

Inflammatory Responses ◽

Rt Pcr ◽

Disulfide Isomerase ◽

Net Production ◽

Protein Disulfide ◽

Dose Dependent

Abstract Abstract 1034 There is growing evidence for an important role of aldosterone (ALDO) in inflammatory responses in addition to its well-described effects on sodium homeostasis via activation of the mineralocorticoid receptor (MR). We studied the effects of ALDO on activation of ex vivo human polymorphonuclear leukocytes (PMNC). We isolated untouched circulating human PMNC by immunomagnetic isolation following density gradient sedimentation with PolymorphPrep from otherwise healthy subjects. Flow cytometric analyses showed greater than 97% of PMNC were positive for myeloid-neutrophil markers, CD45, CD16 and CD66b. We show that PMNC express MR by western blot and RT-PCR analyses and when incubated with ALDO (10−9 −10−7 M) showed a dose-dependent rise in cytosolic Ca2+ that peaked within 2 min using FURA-2AM fluorescence. We then studied the effect of ALDO on PMNC degranulation following incubations with ALDO (10−9 −10−7 M) for 30 min and observed a significant increase in β–glucuronidase release (P<0.001, n=3) by established fluorescent detection methods, an event that was blocked by pre-incubation of cells with 1μM canrenoic acid (CA), an MR antagonist (P<0.04, n=3). PMA and N-Formyl-Methionyl-Leucyl-Phenylalanine (fMLP) were used as positive controls for PMNC activation. We then studied the effects of ALDO on HL-60, a human promyelocytic cell line, induced to differentiate into neutrophil-like cells by incubation for 5 days with 1.3% DMSO. We detected the presence of the mineralocorticoid receptor (MR), the receptor for ALDO, by western blot analyses and MR transcripts by quantitative RT-PCR using TaqMan detection probes in these cells and as reported in kidney and endothelial cells. Cells incubated with ALDO (10−8-10−7 M) showed a dose-dependent rise in cytosolic Ca2+ that peaked within 3 min using FURA-2AM fluorescence. To assess the degranulation response of these cells we quantified the in vitro release of myeloperoxidase (MPO) and observed that 10−8M ALDO was likewise associated with increased degranulation when compared to vehicle treated cells (AUC: 590±14 to 185±11, P<0.01, n=6). To characterize the mechanisms by which ALDO regulates the degranulation responses of these cells we studied the effects of Protein Disulfide Isomerase (PDI) on ALDO-stimulated cells. PDI catalyzes the oxidation or reduction of thiol/disulfide groups and modulates leukocyte function. Our results show that blockade of PDI, by bacitracin, led to a blunted ALDO-stimulated degranulation response in both cell types. Consistent with these observations, we show that in differentiated HL-60 cells, siRNA against PDI likewise led to reduced MPO responses (AUC: 590±14 to 290±13, P<0.01, n=6) that were associated with significantly reduced PDI mRNA levels but not with scrambled siRNA as determined by quantitative RT-PCR with ABI TaqMan detection probes and GAPDH and β2 microglobulin as endogenous controls (0.55 ± 0.02, ΔΔCT of PDI siRNA relative to scrambled transfected cells, P<0.01, n=6). These results suggest that ALDO stimulates MPO release. MPO has been shown to be one of the predominant granule proteins associated with Neutrophil Extracelullar Traps (NETs), extracellular structures that contain chromatin (DNA and histones) that can also trap microorganisms. We studied the effects of ALDO following digestion of the NETs by DNAse, and observed that 30–35% of the total cellular MPO was NET-associated. We also observed that incubation with 10−8 M ALDO led to increases in the oxidative-respiratory burst [superoxide production] (P<0.01, n=3), a responses that was blocked by pre-incubation of cells with 1 uM CA (P<0.03, n=3). Consistent with these results, we observed that ALDO likewise led to significant increases in the oxidative-respiratory burst in human PMNC (P<0.01, n=3). Thus our results suggest that activation of MR by ALDO leads to degranulation and NET production in neutrophils that may contribute to the inflammatory responses associated with MR activation in vivo. Furthermore, the association between degranulation and NET release implicates PDI as a novel regulator of MPO generated NET production. Disclosures: No relevant conflicts of interest to declare.

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Platelet ERp57 Is Required for Hemostasis and Thrombosis.

Blood ◽

10.1182/blood.v120.21.2168.2168 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2168-2168

Author(s):

Lu Wang ◽

Yi Wu ◽

Junsong Zhou ◽

Syed S. Ahmad ◽

Bulent Mutus ◽

...

Keyword(s):

Platelet Aggregation ◽

Platelet Function ◽

Protein Disulfide Isomerase ◽

Conflicts Of Interest ◽

Thrombus Formation ◽

Platelet Glycoprotein ◽

Platelet Surface ◽

Disulfide Isomerase ◽

Protein Disulfide

Abstract Abstract 2168 Several members of the protein disulfide isomerase family of enzymes are important in platelet function and in thrombosis. Platelet protein disulfide isomerase (PDI) has been shown to have an important role in platelet function but is reported to not be required for thrombus formation in vivo. A novel platelet PDI called ERp57 mediates platelet aggregation but its role in thrombus formation is unknown. To determine the specific role of platelet-derived ERp57 in hemostasis and thrombosis we generated a megakaryocyte/platelet specific knockout. Despite normal platelet counts and platelet glycoprotein expression, mice with ERp57-deficient platelets had prolonged tail-bleeding times and thrombus occlusion times, and defective activation of the αIIbβ3 integrin and platelet aggregation. The aggregation defect was corrected by addition of exogenous ERp57 implicating surface ERp57 in platelet aggregation. Platelet surface ERp57 protein and activity increased substantially with platelet activation. We conclude that platelet-derived ERp57 is required for hemostasis and thrombosis and platelet function. Disclosures: No relevant conflicts of interest to declare.

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Differential expression of protein disulfide-isomerase A3 isoforms, PDIA3 and PDIA3N, in human prostate cancer cell lines representing different stages of prostate cancer

Molecular Biology Reports ◽

10.1007/s11033-021-06277-1 ◽

2021 ◽

Author(s):

Maria Araceli Diaz Cruz ◽

Sandra Karlsson ◽

Ferenc Szekeres ◽

Maria Faresjö ◽

Dan Lund ◽

...

Keyword(s):

Prostate Cancer ◽

Vitamin D ◽

Mrna Expression ◽

Cell Lines ◽

Protein Function ◽

Protein Disulfide Isomerase ◽

Expression Ratio ◽

Disulfide Isomerase ◽

Vitamin D Receptors ◽

Protein Disulfide

AbstractProstate cancer (PCa) is a highly heterogeneous and unpredictable progressive disease. Sensitivity of PCa cells to androgens play a central role in tumor aggressiveness but biomarkers with high sensitivity and specificity that follow the progression of the disease has not yet been verified. The vitamin D endocrine system and its receptors, the Vitamin D Receptor (VDR) and the Protein Disulfide-Isomerase A3 (PDIA3), are related to anti-tumoral effects as well as carcinogenesis and have therefore been suggested as potential candidates for the prevention and therapy of several cancer forms, including PCa. In this study, we evaluated the mRNA expression of VDR and PDIA3 involved in vitamin D signaling in cell lines representing different stages of PCa (PNT2, P4E6, LNCaP, DU145 and PC3). This study further aimed to evaluate vitamin D receptors and their isoforms as potential markers for clinical diagnosis of PCa. A novel transcript isoform of PDIA3 (PDIA3N) was identified and found to be expressed in all PCa cell lines analyzed. Androgen-independent cell lines showed a higher mRNA expression ratio between PDIA3N/PDIA3 contrary to androgen-dependent cell lines that showed a lower mRNA expression ratio between PDIA3N/PDIA3. The structure of PDIA3N differed from PDIA3. PDIA3N was found to be a N-truncated isoform of PDIA3 and differences in protein structure suggests an altered protein function i.e. cell location, thioredoxin activity and affinity for 1,25(OH)2D3. Collectively, PDIA3 transcript isoforms, the ratio between PDIA3N/PDIA3 and especially PDIA3N, are proposed as candidate markers for future studies with different stages of PCa progression.

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Abstract 264: Protein Disulfide Isomerase A1 is a Central Hub for Redox Regulation of VSMC Phenotype

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.37.suppl_1.264 ◽

2017 ◽

Vol 37 (suppl_1) ◽

Author(s):

Joao Wosniak ◽

Renata C Gonçalves ◽

Leonardo Y Tanaka ◽

Daniela B Zanatta ◽

Bryan E Strauss ◽

...

Keyword(s):

Protein Disulfide Isomerase ◽

Redox Regulation ◽

Lentiviral Vector ◽

Ex Vivo ◽

Mrna Levels ◽

Disulfide Isomerase ◽

Cytoskeleton Organization ◽

Anisotropy Index ◽

Differentiation Marker ◽

Protein Disulfide

Objective: Vascular smooth muscle cell (VSMC) phenotype switch depends on extrinsic/intrinsic cues including NOX NADPH oxidase-linked redox signaling. Growth factor-triggered NOX1 expression/activity requires the chaperone oxidoreductase protein disulfide isomerase-A1 (PDI). Acute PDI overexpression induces agonist-independent NOX1 expression. PDI is required for VSMC migration and cytoskeleton organization, and extracellular PDI supports expansive vascular remodeling via cytoskeleton reshaping. Such PDI effects led us to hypothesize that PDI may orchestrate VSMC phenotypic alterations. Approach and Results: In primary VSMC, PDI silencing spontaneously decreased differentiation marker expression. Transfection with a doxycycline-inducible lentiviral vector encoding PDI showed that sustained PDI overexpression (72h) enhanced actin branching pattern vs. baseline (anisotropy index, 0.103±0.019 vs. 0.220±0.027, 72h vs. 0h, mean±SEM, N=5, P<0.05), increased cell length and induced expression of differentiation marker calponin (2-fold, 72h vs 0h, N=5, P<0.05), alpha-actin and smoothelin, which were abrogated upon catalase incubation. Intracellular superoxide enhanced upon 48h of PDI overexpression (2-hydroxyethidium levels, 0.998±0.102 vs. 2.887±0.227 AU, N=4, P<0.05) and was NOX1-dependent, based on inhibition with GKT136901 (by 48%) or NOXA1ds peptide (by 54%) (N=6, P<0.05). Increased NOX1 mRNA occurred early after PDI overexpression (74%, 24h vs. 0h, N=4, P<0.05), while NOX4 mRNA was upregulated only after long-term PDI induction (100%, 72h vs. 0h, N=4, P<0.05). In rabbit restenosis model exhibiting strong PDI upregulation (12-fold at day 14 after injury), ex vivo PDI silencing 7 or 14 days after injury reversed PCNA expression, while promoting increased NOX1 and decreased NOX4 mRNA levels (+54% and -45%, respectively, siPDI vs. siSCR, N=3, P<0.05 for both). Conclusions: While short-term PDI overexpression supports NOX1 activation/expression, sustained PDI overexpression drives NOX4 expression and VSMC differentiation. Effects on cytoskeleton, NOX1/4 activation and temporal control of NOX1/4 expression suggest a central role for PDI as a hub for redox-mediated VSMC phenotype regulation.

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Characterization of a Foldase, Protein Disulfide Isomerase A, in the Protein Secretory Pathway ofAspergillus niger

Applied and Environmental Microbiology ◽

10.1128/aem.66.2.775-782.2000 ◽

2000 ◽

Vol 66 (2) ◽

pp. 775-782 ◽

Cited By ~ 66

Author(s):

Celina Ngiam ◽

David J. Jeenes ◽

Peter J. Punt ◽

Cees A. M. J. J. Van Den Hondel ◽

David B. Archer

Keyword(s):

Protein Disulfide Isomerase ◽

Secretory Pathway ◽

Functional Characterization ◽

Killer Toxin ◽

Rnase A ◽

Secretory Proteins ◽

Mrna Levels ◽

Western Blots ◽

Disulfide Isomerase ◽

Protein Disulfide

ABSTRACT Protein disulfide isomerase (PDI) is important in assisting the folding and maturation of secretory proteins in eukaryotes. A gene,pdiA, encoding PDIA was previously isolated fromAspergillus niger, and we report its functional characterization here. Functional analysis of PDIA showed that it catalyzes the refolding of denatured and reduced RNase A.pdiA also complemented PDI function in aSaccharomyces cerevisiae Δpdi1 mutant in a yeast-based killer toxin assay. Levels of pdiA mRNA and PDIA protein were raised by the accumulation of unfolded proteins in the endoplasmic reticulum. This response of pdiA mRNA levels was slower and lower in magnitude than that of A. niger bipA, suggesting that the induction of pdiA is not part of the primary stress response. An increased level of pdiA transcripts was also observed in two A. niger strains overproducing a heterologous protein, hen egg white lysozyme (HEWL). Although overexpression of PDI has been successful in increasing yields of some heterologous proteins in S. cerevisiae, overexpression of PDIA did not increase secreted yields of HEWL in A. niger, suggesting that PDIA itself is not limiting for secretion of this protein. Downregulation of pdiA by antisense mRNA reduced the levels of microsomal PDIA activity by up to 50%, lowered the level of PDIA as judged by Western blots, and lowered the secreted levels of glucoamylase by 60 to 70%.

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Endothelial-Specific Knockdown Of Caveolin-1 Lowers Circulating Protein Disulfide Isomerase Levels and Is Associated With Changes In Erythrocyte Volume Homeostasis

Blood ◽

10.1182/blood.v122.21.12.12 ◽

2013 ◽

Vol 122 (21) ◽

pp. 12-12

Author(s):

Josue A. Benabe-Carlo ◽

Jose R Romero ◽

Enrique D. Machado-Fiallo ◽

Arelys Ramos-Rivera ◽

Gregory N. Prado ◽

...

Keyword(s):

Endothelial Cells ◽

Protein Disulfide Isomerase ◽

Conflicts Of Interest ◽

Mean Cell Volume ◽

Distribution Width ◽

Disulfide Isomerase ◽

Erythrocyte Volume ◽

Caveolin 1 ◽

Protein Disulfide

Abstract We have recently reported that Endothelin-1 (ET1), a potent vasoconstrictor peptide, is implicated in the pathophysiology of Sickle Cell Disease (SCD) via increased circulating Protein Disulfide Isomerase (PDI) activity (Prado, 2013 FASEB J). PDI is a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, catalyzes disulfide interchange reactions in the plasma membrane, regulates KCNN4 channel and erythrocyte volume and is up-regulated under hypoxic conditions as commonly observed in SCD. In erythrocytes, ET1 stimulates PDI activity via activation of ET1 receptor B (ETRB). However, the precise mechanisms by which ET1 leads to increases in PDI are not entirely clear. There is evidence that activation of endothelial cells leads to increased PDI secretion and that ETRBs form a complex with caveolin-1 (CAV1) within caveolae to mediate ET1’s cellular effects. We tested the hypothesis that reduction of CAV1 would alter PDI secretion. We studied the in vivo effects of endothelial-specific CAV1 knockdown on circulating PDI activity in mice. We optimized conditions to measure circulating PDI using fluorescently labeled GSSG conversion to GSH. We now report that circulating plasma PDI levels were significantly decreased in CAV1 knockdown mice when compared to wild-type littermates (WT) (7.44±0.70 vs 10.93±2.66, n=7, P<0.05). In addition and consistent with our report showing a role for PDI in erythrocyte volume regulation, we also observed lower cell hemoglobin concentration mean (CHCM) and hemoglobin distribution width (HDW) that was associated with increased erythrocyte and reticulocyte mean cell volume (MCV) in blood from CAV1 knockdown mice when compared to WT (n=13 and n=19, respectively, P<0.005). We then isolated early cultures of mouse aortic endothelial cells (MAEC) from these mice and measured PDI activity following 24 hrs of incubation in 0.4% fetal bovine serum. Our results show that MAEC from CAV1 knockdown mice had lower PDI secretion when compared to cells from WT mice (99.4±16 vs 129.9±35, n=5, P<0.03). We then studied the effects of ET1 on PDI secretion from human endothelial cells. We detected PDI and ETRB by western blot analyses in membranes from the human endothelial cell line, EA.hy926 (EA). We observed that incubation of EA cells for 60 mins with 10-7 M ET1 was associated with increased extracellular PDI activity (15.97±7.22 to 34.07±8.89 [RFU/mg protein], n=3, P<0.011) that was sensitive to preincubation with BQ788, a specific ETRB receptor antagonist (15.97±7.22 to 7.97±3.25 (RFU/mg protein), n=3, P<0.02). Similar increases in PDI were observed when cells were treated with the specific ETRB agonist, IRL1620 (1143±137 to 1593 207 RFU/mg protein). In addition, PDI siRNA knockdown was associated with reduced ET1-stimulated PDI activity when compared to scrambled siRNA transfected cells (1731±147 to 757±141 RFU, n=2). We then tested the effects of methyl-β-cyclodextrin to disrupt caveolae in these cells and observed a blunted IRL1620–stimulated PDI response (288±40 to 171±14 RFU/mg protein, n=3, P<0.025). We also characterized the effects of ET1 on PDI expression in EA cells, using quantitative RT-PCR with ABI TaqMan probes and β-actin as an endogenous control and observed that stimulation of EA cells with 10-8 M ET1 for 4 hr was associated with increased PDI mRNA expression levels that were 1.89 fold greater than vehicle treated cells (n=6, P<0.04). Thus our results provide evidence for a heretofore unrecognized role of endothelial specific CAV1 in erythrocyte volume and circulating PDI levels. Supported by NIH R01HL090632 (AR) and R01HL104032 (LHP). Disclosures: No relevant conflicts of interest to declare.

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Protein disulfide isomerase overexpression in vascular smooth muscle cells induces spontaneous preemptive NADPH oxidase activation and Nox1 mRNA expression: Effects of nitrosothiol exposure

Archives of Biochemistry and Biophysics ◽

10.1016/j.abb.2009.01.022 ◽

2009 ◽

Vol 484 (2) ◽

pp. 197-204 ◽

Cited By ~ 64

Author(s):

Denise C. Fernandes ◽

Ana Heloisa O. Manoel ◽

João Wosniak ◽

Francisco R. Laurindo

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Nadph Oxidase ◽

Smooth Muscle Cells ◽

Mrna Expression ◽

Vascular Smooth Muscle Cells ◽

Protein Disulfide Isomerase ◽

Disulfide Isomerase ◽

Protein Disulfide ◽

Nadph Oxidase Activation

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Aldosterone Stimulates Neutrophils Leading To Increased β-Glucuronidase, Protein Disulfide Isomerase and Myeloperoxidase Secretion

Blood ◽

10.1182/blood.v122.21.2271.2271 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2271-2271

Author(s):

Arelys Ramos-Rivera ◽

Alicia Rivera ◽

Enrique D. Machado-Fiallo ◽

Josue A. Benabe-Carlo ◽

Gregory N. Prado ◽

...

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Respiratory Burst ◽

Protein Disulfide Isomerase ◽

Mrna Levels ◽

Dependent Manner ◽

Cell Disease ◽

Rt Pcr ◽

Disulfide Isomerase ◽

Protein Disulfide

Abstract Aldosterone (ALDO) has been shown to play an important role in inflammatory responses in addition to its well described effects on sodium homeostasis via activation of the mineralocorticoid receptor (MR). However, its effects on polymorphonuclear leukocytes (PMNC) are not well described. We isolated untouched circulating human PMNC by immunomagnetic isolation following density gradient sedimentation with PolymorphPrep from otherwise healthy subjects. Flow cytometric analyses showed greater than 97% of PMNC were positive for the myeloid-neutrophil markers, CD45, CD16 and CD66b. We show that PMNC express MR by western blot and RT-PCR analyses. We incubated PMNC with ALDO (10–9–10–7M) for 30 min and observed a dose-dependent rise in β–glucuronidase release with an EC50 of 6.11 nM (P<0.001, n=3), an event that was blocked by pre-incubation of cells with 1μM canrenoic acid (CA), an MR antagonist (P<0.04, n=3). In addition, our results show that incubation of human PMNC with 10-8M ALDO likewise led to increases in myeloperoxidase ([MPO], P<0.05, n=3) and protein disulfide isomerase ([PDI], P<0.01, n=4), a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, regulates KCNN4 channel and erythrocyte volume and is up-regulated under hypoxic conditions (Prado, 2013 FASEB J). We then studied the effects of ALDO on HL-60, a human promyelocytic cell line, induced to differentiate into neutrophil-like cells by incubation for 5 days with 1.3% DMSO. Our results likewise show an increase in MPO responses upon 10–8M ALDO stimulation as compared to vehicle (AUC: 1090±147 to 505±48, P<0.02, n=3). We have recently reported that aldosterone stimulates increases of striatin, a scaffolding protein that interacts with caveolin-1, and co-precipitates with striatin and as such may facilitate cross talk of signaling complexes. As there are no pharmacological inhibitors of striatin we used a molecular approach to reduce striatin levels. In differentiated HL-60 cells, siRNA against striatin led to reduced MPO responses (AUC: 590±14 to 528±13, P<0.05, n=3) that were associated with significantly reduced striatin mRNA levels but not when cells were transfected with scrambled siRNA as determined by quantitative RT-PCR with ABI TaqMan detection probes and β-microglobulin used as an endogenous control (P<0.01, n=3). These results suggest that striatin plays an important role in ALDO-stimulated degranulation responses. Of importance we also observed that incubation with ALDO (10–9–10–7M) in differentiated HL60 cells led to increases in the oxidative-respiratory burst [superoxide production] in a dose- and time-dependent manner (P<0.01, n=4). Consistent with these results, we observed that ALDO likewise led to significant increases in the oxidative-respiratory burst in human PMNC (P<0.01, n=3). As there is evidence that activated neutrophils, MPO and PDI are elevated in Sickle Cell Disease, we studied the in vivo effects of MR blockade in BERK sickle transgenic mice, a model of increased oxidative stress. Sickle mice were randomized to receive either normal rodent chow or chow containing eplerenone (156 mg/kg per day), an MR receptor antagonist, and tap water ad libitum for 14 days at which time the mice were sacrificed and blood collected. We observed that mice on eplerenone had significantly lower plasma PDI activity than mice on regular chow (63.7 ± 8.7 control diet to 47.9 ± 2.4 eplerenone, Relative Fluorescence Units [RFU]; P<0.005, n=6 and 9) and lower MPO levels (AUC: 214±11 to 73±20, P<0.03, n=3); events that were associated with increases in both erythrocyte MCV (41.3±2.5 vs 47.4±1.1 fL, P<0.03, n=7) and reticulocyte MCV (53.6.3±2.8 vs 60.1±0.6 fL, P<0.02, n=7). Thus, our results suggest that MR activation by ALDO is a novel mechanism for neutrophil stimulation and as such represents a novel therapeutic target aimed at ameliorating the vascular complications of Sickle Cell Disease. Supported by NIH R01HL090632 (AR) and R01HL096518 (JRR). Disclosures: No relevant conflicts of interest to declare.

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