Endothelin-1 induces endoplasmic reticulum stress by activating the PLC-IP(3) pathway: implications for placental pathophysiology in preeclampsia

Dabigatran Combined With Benztropine Ameliorates Cobalt Chloride-Induced Parkinsonism in Rats, Restores Protease-Activated Receptor 1 (PAR1), and Mitigates Oxidative Stress

BACKGROUND

The presumed implication of thromboembolic and oxidative stress pathways in parkinsonism guided the current research toward the exploration of the anticoagulant dabigatran etexilate (DE) as a thrombin inhibitor in the cobalt chloride (CoCl2)-induced parkinsonism (CIP) model, a model of significance to industrial toxins-related health issues.

METHODS

Oral CoCl2 (12.5 mg/kg) was administered daily for 60 days, with the introduction of benztropine mesylate (BM) (10 mg/kg) and/or DE (3 mg/kg) on day 31. Rearing, postural instability, and pasta handling were evaluated, followed by histopathologic examination of the substantia nigra (SN) and striatum (STR). The expressions of brain dopamine receptor 2 (D2 ), adenosine receptor 1 (A1) and 2A (A2A), and protease-activated receptor 1 (PAR1), as well as the brain levels of dopamine (DA), endothelin 1 (ET1), malondialdehyde (MDA), and glutathione (GSH), were assessed.

RESULTS

BM+DE restored the number of rears to the control level, compared to being reduced in the CIP model. BM+DE restored the first, second, third, and average displacement distances to the control level, compared to being reduced in the CIP model. BM+DE was superior to either BM or DE in restoring the time to finish eating pasta and the number of adjustments of forepaws while eating to control levels after being affected in the CIP model. BM+DE restored DA to the control level and was superior to DE in restoring D2  to the control level. BM+DE was superior to BM in restoring A1 and A2A , increasing A1/A2A beyond the control level. BM+DE was superior to BM in restoring PAR1 and ET1 to control levels. BM+DE was superior to BM in restoring MDA to the control level and was superior to both BM and DE in increasing GSH beyond the control level. BM+DE exhibited the highest percentage of preserved neurons in SN, which was negatively correlated with MDA.

CONCLUSION

BM+DE offers a therapeutic potential for parkinsonism triggered by chronic exposure to CoCl2. The implication of thrombin-related factors and oxidative stress in the modulation of the dopaminergic-adenosinergic crosstalk is plausible.

Endothelin-1 potentiated constriction in preeclampsia placental veins: Role of ETAR/ETBR/CaV1.2/CALD1

BACKGROUND

Placenta plays a vital role in preeclampsia. The present study investigated the role of endothelin-1 (ET-1) and its receptors in preeclampsia placenta.

METHOD

Placenta samples were collected from normal and preeclampsia pregnancies, with one single fetus. Placental chorionic plate vessel tone was measured with DMT using vasoactive agents with or without antagonists. Role of L-type voltage-dependent calcium channels (CaV1.2) in single smooth muscle cell was detected using whole-cell patch clamp. PCR, Western blot, and ELISA was used to detect molecule expressions. Placental vessel explants and human umbilical vein smooth muscle cell (HUVSMC) were exposed to ET-1 treatment with or without antagonists. Human umbilical vein endothelial cell (HUVEC) and pregnant sheep was exposed to hypoxic condition, simulating preeclampsia.

RESULTS

ET-1 and IRL1620 mediated stronger contractions in preeclampsia placental veins, despite unchanged ETAR and decreased ETBR expression. Comparing with control, there was higher ET-1 in umbilical plasma, maternal plasma, and placental vessels from preeclampsia. In utero hypoxia increased plasma ET-1 in fetal lambs and ewes. Hypoxia promoted ET-1 production in HUVEC. Role and expression of CaV1.2 was decreased in preeclampsia placental vessels, while high-molecular-weight caldesmon (CALD1), the marker of contractile phenotype of smooth muscle cells, was significantly increased. ET-1 treatment increased CALD1 in placental explants and in HUVSMC via ETAR/ETBR.

CONCLUSION

The present study firstly demonstrated ET-1 induced greater contraction in preeclampsia placental chorionic plate veins via ETAR/ETBR, instead of via weaker CaV1.2. In utero hypoxia promoted plasma ET-1 in fetal lambs and ewe, similar to that in preeclampsia. ET-1, binding with ETAR/ETBR increased CALD1, which was associated with stronger contraction in preeclampsia. The data provided important information in preeclampsia onset.

Oxidative Stress and Endoplasmic Reticular Stress Interplay in the Vasculopathy of Hypertension

Under physiologic conditions, reactive oxygen species (ROS) function as signalling molecules that control cell function. However, in pathologic conditions, increased generation of ROS triggers oxidative stress, which plays a role in vascular changes associated with hypertension, including endothelial dysfunction, vascular reactivity, and arterial remodelling (termed the vasculopathy of hypertension). The major source of ROS in the vascular system is NADPH oxidase (NOX). Increased NOX activity drives vascular oxidative stress in hypertension. Molecular mechanisms underlying vascular damage in hypertension include activation of redox-sensitive signalling pathways, post-translational modification of proteins, and oxidative damage of DNA and cytoplasmic proteins. In addition, oxidative stress leads to accumulation of proteins in the endoplasmic reticulum (ER) (termed ER stress), with consequent activation of the unfolded protein response (UPR). ER stress is emerging as a potential player in hypertension as abnormal protein folding in the ER leads to oxidative stress and dysregulated activation of the UPR promotes inflammation and injury in vascular and cardiac cells. In addition, the ER engages in crosstalk with exogenous sources of ROS, such as mitochondria and NOX, which can amplify redox processes. Here we provide an update of the role of ROS and NOX in hypertension and discuss novel concepts on the interplay between oxidative stress and ER stress.

ET-traps: Potential therapeutics for preeclampsia

Elevated endothelin-1 (ET-1) has been implicated in several diseases including preeclampsia, where it causes the induction of hypertension, oxidative stress, endoplasmic reticulum stress, microvascular dysfunction and tissue damage in different organs. ET-traps are Fc-fusion proteins with a design based on the physiological receptors of ET-1. This paper discusses the potential use of ET-traps as a therapeutic for preeclampsia. ET-traps potently bind and sequester pathologically elevated ET-1 to significantly reduce different markers of pathology to non-disease levels with no toxicity.

Overexpression of Decay Accelerating Factor Mitigates Fibrotic Responses to Lung Injury

CD55 or decay accelerating factor (DAF), a ubiquitously expressed glycosylphosphatidylinositol (GPI)-anchored protein, confers a protective threshold against complement dysregulation which is linked to the pathogenesis of idiopathic pulmonary fibrosis (IPF). Since lung fibrosis is associated with downregulation of DAF, we hypothesize that overexpression of DAF in fibrosed lungs will limit fibrotic injury by restraining complement dysregulation. Normal primary human alveolar type II epithelial cells (AECs) exposed to exogenous complement 3a or 5a, and primary AECs purified from IPF lungs demonstrated decreased membrane-bound DAF expression with concurrent increase in the endoplasmic reticulum (ER) stress protein, ATF6. Increased loss of extracellular cleaved DAF fragments was detected in normal human AECs exposed to complement 3a or 5a, and in lungs of IPF patients. C3a-induced ATF6 expression and DAF loss was inhibited using pertussis toxin (an enzymatic inactivator of G-protein coupled receptors), in murine AECs. Treatment with soluble DAF abrogated tunicamycin-induced C3a secretion and ER stress (ATF6 and BiP expression) and restored epithelial cadherin. Bleomycin-injured fibrotic mice subjected to lentiviral overexpression of DAF demonstrated diminished levels of local collagen deposition and complement activation. Further analyses showed diminished release of DAF fragments, as well as reduction in apoptosis (TUNEL and caspase 3/7 activity), and ER stress-related transcripts. Loss-of-function studies using Daf1 siRNA demonstrated worsened lung fibrosis detected by higher mRNA levels of Col1a1 and epithelial injury-related Muc1 and Snai1, with exacerbated local deposition of C5b-9. Our studies provide a rationale for rescuing fibrotic lungs via DAF induction that will restrain complement dysregulation and lung injury.

Ryanodine receptor calcium release channels in trophoblasts and their role in cell migration

Trophoblasts are specialized epithelial cells of the placenta that are involved in invasion, communication and the exchange of materials between the mother and fetus. Cytoplasmic Ca²⁺ ([Ca²⁺]_c) plays critical roles in regulating such processes in other cell types, but relatively little is known about the mechanisms that control this second messenger in trophoblasts. In the current study, the presence of RyRs and their accessory proteins in placental tissues and in the BeWo choriocarcinoma, a model trophoblast cell-line, were examined using immunohistochemistry and Western immunoblotting. Contributions of RyRs to Ca²⁺ signalling and to random migration in BeWo cells were investigated using fura-2 fluorescent and brightfield videomicroscopy. The effect of RyR inhibition on reorganization of the F-actin cytoskeleton elicited by the hormone angiotensin II, was determined using phalloidin-labelling and confocal microscopy. RyR1 and RyR3 proteins were detected in trophoblasts of human first trimester and term placental villi, along with the accessory proteins triadin and calsequestrin. Similarly, RyR1, RyR3, triadin and calsequestrin were detected in BeWo cells. In this cell-line, activation of RyRs with micromolar ryanodine increased [Ca²⁺]_c, whereas pharmacological inhibition of these channels reduced Ca²⁺ transients elicited by the peptide hormones angiotensin II, arginine vasopressin and endothelin 1. Angiotensin II increased the velocity, total distance and Euclidean distance of random migration by BeWo cells and these effects were significantly reduced by tetracaine and by inhibitory concentrations of ryanodine. RyRs contribute to reorganization of the F-actin cytoskeleton elicited by angiotensin II, since inhibition of these channels restores the parallelness of these structures to control levels. These findings demonstrate that trophoblasts contain a suite of proteins similar to those in other cell types possessing highly developed Ca²⁺ signal transduction systems, such as skeletal muscle. They also indicate that these channels regulate the migration of trophoblast cells, a process that plays a key role in development of the placenta.

Potential Roles of Endoplasmic Reticulum Stress and Cellular Proteins Implicated in Diabesity

The role of the endoplasmic reticulum (ER) has evolved from protein synthesis, processing, and other secretory pathways to forming a foundation for lipid biosynthesis and other metabolic functions. Maintaining ER homeostasis is essential for normal cellular function and survival. An imbalance in the ER implied stressful conditions such as metabolic distress, which activates a protective process called unfolded protein response (UPR). This response is activated through some canonical branches of ER stress, i.e., the protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6). Therefore, chronic hyperglycemia, hyperinsulinemia, increased proinflammatory cytokines, and free fatty acids (FFAs) found in diabesity (a pathophysiological link between obesity and diabetes) could lead to ER stress. However, limited data exist regarding ER stress and its association with diabesity, particularly the implicated proteins and molecular mechanisms. Thus, this review highlights the role of ER stress in relation to some proteins involved in diabesity pathogenesis and provides insight into possible pathways that could serve as novel targets for therapeutic intervention.

Therapeutic Effect of Endothelin-Converting Enzyme Inhibitor on Chronic Kidney Disease through the Inhibition of Endoplasmic Reticulum Stress and the NLRP3 Inflammasome

Chronic inflammation and oxidative stress significantly contribute to the development and progression of chronic kidney disease (CKD). The NOD-like receptor family pyrin containing domain-3 (NLRP3) inflammasome plays a key role in the inflammatory response. The renal endothelin (ET) system is activated in all cases of CKD. Furthermore, ET-1 promotes renal cellular injury, inflammation, fibrosis and proteinuria. Endothelin-converting enzymes (ECEs) facilitate the final processing step of ET synthesis. However, the roles of ECEs in CKD are not clear. In this study, we investigated the effects of ETs and ECEs on kidney cells. We found that ET-1 and ET-2 expression was significantly upregulated in the renal tissues of CKD patients. ET-1 and ET-2 showed no cytotoxicity on human kidney tubular epithelial cells. However, ET-1 and ET-2 caused endoplasmic reticulum (ER) stress and NLRP3 inflammasome activation in tubular epithelial cells. The ECE inhibitor phosphoramidon induced autophagy. Furthermore, phosphoramidon inhibited ER stress and the NLRP3 inflammasome in tubular epithelial cells. In an adenine diet-induced CKD mouse model, phosphoramidon attenuated the progression of CKD by regulating autophagy, the NLRP3 inflammasome and ER stress. In summary, these findings showed a new strategy to delay CKD progression by inhibiting ECEs through autophagy activation and restraining ER stress and the NLRP3 inflammasome.

Endothelin 1-induced retinal ganglion cell death is largely mediated by JUN activation

Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells (RGCs), the output neurons of the retina. Multiple lines of evidence show the endothelin (EDN, also known as ET) system is important in glaucomatous neurodegeneration. To date, the molecular mechanisms within RGCs driving EDN-induced RGC death have not been clarified. The pro-apoptotic transcription factor JUN (the canonical target of JNK signaling) and the endoplasmic reticulum stress effector and transcription factor DNA damage inducible transcript 3 (DDIT3, also known as CHOP) have been shown to act downstream of EDN receptors. Previous studies demonstrated that JUN and DDIT3 were important regulators of RGC death after glaucoma-relevant injures. Here, we characterized EDN insult in vivo and investigated the role of JUN and DDIT3 in EDN-induced RGC death. To accomplish this, EDN1 ligand was intravitreally injected into the eyes of wildtype, Six3-cre⁺Jun^fl/fl (Jun^-/-), Ddit3 null (Ddit3^-/-), and Ddit3^-/-Jun^-/- mice. Intravitreal EDN1 was sufficient to drive RGC death in vivo. EDN1 insult caused JUN activation in RGCs, and deletion of Jun from the neural retina attenuated RGC death after EDN insult. However, deletion of Ddit3 did not confer significant protection to RGCs after EDN1 insult. These results indicate that EDN caused RGC death via a JUN-dependent mechanism. In addition, EDN signaling is known to elicit potent vasoconstriction. JUN signaling was shown to drive neuronal death after ischemic insult. Therefore, the effects of intravitreal EDN1 on retinal vessel diameter and hypoxia were explored. Intravitreal EDN1 caused transient retinal vasoconstriction and regions of RGC and Müller glia hypoxia. Thus, it remains a possibility that EDN elicits a hypoxic insult to RGCs, causing apoptosis via JNK-JUN signaling. The importance of EDN-induced vasoconstriction and hypoxia in causing RGC death after EDN insult and in models of glaucoma requires further investigation.

Down-regulation of EDN1 gene expression by circulating miR-206 is associated with risk of preeclampsia

To study the correlation between circulating microRNA-206 (miR-206) levels and endothelin-1 (ET-1) levels, and to explore its association with preeclampsia (PE) risk.Reverse transcription-PCR (RT-PCT) was used to compare the plasma miR-206 levels in 200 PE patients and 200 healthy controls. The correlation between miR-206 and ET-1 levels in plasma of PE patients was analyzed by Pearson analysis. MiR-206 was transfected into human umbilical vein endothelial cells cells and ET-1 expression was analyzed by enzyme-linked immunosorbent assay.RT-PCR results showed that plasma miR-206 levels in PE patients were significantly higher than those in the control group (P < .01). The results of receiver operating characteristic curve analysis showed that the area under the curve of plasma miR-206 level in the diagnosis of PE was 0.94 (95% confidence interval: 0.92-0.96). Plasma ET-1 levels in PE patients were significantly lower than those in the control group by enzyme-linked immunosorbent assay (P < .01). The area under the curve of plasma ET-1 level in the diagnosis of PE was 0.92 (95% confidence interval: 0.90-0.95). The level of miR-206 in plasma was negative correlated with ET-1 level (r = -0.37, P < .01). The expression level of ET-1 was significantly decreased in human umbilical vein endothelial cells cells transfected with miR-206.miR-206 can down-regulate the expression of EDN1 gene, which may be related to the increased risk of preeclampsia.

Sex differences in redox homeostasis in renal disease

Sex differences in redox signaling in the kidney present new challenges and opportunities for understanding the physiology and pathophysiology of the kidney. This review will focus on reactive oxygen species, immune-related signaling pathways and endothelin-1 as potential mediators of sex-differences in redox homeostasis in the kidney. Additionally, this review will highlight male-female differences in redox signaling in several major cardiovascular and renal disorders namely acute kidney injury, diabetic nephropathy, kidney stone disease and salt-sensitive hypertension. Furthermore, we will discuss the contribution of redox signaling in the pathogenesis of postmenopausal hypertension and preeclampsia.

AQP1 suppression by ATF4 triggers trabecular meshwork tissue remodelling in ET-1-induced POAG

Primary open‐angle glaucoma (POAG) is the second leading cause of irreversible blindness worldwide. Increased endothelin‐1 (ET‐1) has been observed in aqueous humour (AH) of POAG patients, resulting in an increase in the out‐flow resistance of the AH. However, the underlining mechanisms remain elusive. Using established in vivo and in vitro POAG models, we demonstrated that water channel Aquaporin 1 (AQP1) is down‐regulated in trabecular meshwork (TM) cells upon ET‐1 exposure, which causes a series of glaucomatous changes, including actin fibre reorganization, collagen production, extracellular matrix deposition and contractility alteration of TM cells. Ectopic expression of AQP1 can reverse ET‐1‐induced TM tissue remodelling, which requires the presence of β‐catenin. More importantly, we found that ET‐1‐induced AQP1 suppression is mediated by ATF4, a transcription factor of the unfolded protein response, which binds to the promoter of AQP1 and negatively regulates AQP1 transcription. Thus, we discovered a novel function of ATF4 in controlling the process of TM remodelling in ET‐1‐induced POAG through transcription suppression of AQP1. Our findings also detail a novel pathological mechanism and a potential therapeutic target for POAG.

ROR2 induces cell apoptosis via activating IRE1α/JNK/CHOP pathway in high-grade serous ovarian carcinoma in vitro and in vivo

Background

Epithelial ovarian cancer (EOC) is the most lethal cancer in female genital tumors. New disease markers and novel therapeutic strategies are urgent to identify considering the current status of treatment. Receptor tyrosine kinases family plays critical roles in embryo development and disease progression. However, ambivalent research conclusions of ROR2 make its role in tumor confused and the underlying mechanism is far from being understood. In this study, we sought to clarify the effects of ROR2 on high-grade serous ovarian carcinoma (HGSOC) cells and reveal the mechanism.

Methods

Immunohistochemistry assay and western-blot assay were used to detect proteins expression. ROR2 overexpression adenovirus and Lentivirus were used to create ROR2 overexpression model in vitro and in vivo, respectively. MTT assay, colony formation assay and transwell assay were used to measure the proliferation, invasion and migration ability of cancer cells. Flow cytometry assay was used to detect cell apoptosis rate. Whole transcriptome analysis was used to explore the differentially expressed genes between ROR2 overexpression group and negative control group. SiRNA targeted IRE1α was used to knockdown IRE1α. Kira6 was used to inhibit phosphorylation of IRE1α.

Results

Expression of ROR2 was significantly lower in HGSOC tissues compared to normal fallopian tube epithelium or ovarian surface epithelium tissues. In HGSOC cohort, patients with advanced stages or positive lymph nodes were prone to express lower ROR2. Overexpression of ROR2 could repress the proliferation of HGSOC cells and induce cell apoptosis. RNA sequencing analysis indicated that ROR2 overexpression could induce unfold protein response. The results were also confirmed by upregulation of BIP and phosphorylated IRE1α. Furthermore, pro-death factors like CHOP, phosphorylated JNK and phosphorylated c-Jun were also upregulated. IRE1α knockdown or Kira6 treatment could reverse the apoptosis induced by ROR2 overexpression. Finally, tumor xenograft experiment showed ROR2 overexpression could significantly repress the growth rate and volume of transplanted tumors.

Conclusions

Taken together, ROR2 downregulation was associated with HGSOC development and progression. ROR2 overexpression could repress cell proliferation and induce cell apoptosis in HGSOC cells. And the underlying mechanism might be the activation of IRE1α/JNK/CHOP pathway induced by ROR2.

HIF-1α regulates angiogenesis via Notch1/STAT3/ETBR pathway in trophoblastic cells

Background: Preeclampsia is a pregnancy-related complication and the major cause to maternal and fetal mortality. Despite extensive studies, the pathogenesis of this disease still remains unknown. Here we explored the roles of HIF-1α and Notch1/ETBR in preeclampsia.Methods: Immunohistochemistry, RT-qPCR and western blot were used to measure levels of Notch1 and ETBR in placentas of preeclampsia patients. Transwell invasion assay and in vitro Matrigel assay were used to test the functions of Notch1, HIF-1α and ETBR in invasion and angiogenesis of trophoblast cells. In addition, we used reduced uterine perfusion pressure (RUPP) rat model to study preeclampsia in vivo.Results: We found that Notch1 and ETBR were down-regulated in the placenta of patients with preeclampsia. Hypoxia promoted invasion and angiogenesis of trophoblast cells, and up-regulated expressions of HIF-1α, Notch1/ETBR. Overexpression of Notch1 facilitated invasion and angiogenesis of trophoblast cells while HIF-1α inhibitor suppressed. Furthermore, Notch1 or ETBR could promote angiogenesis of trophoblast cells in RUPP rats.Conclusions: Our study reveals that HIF-1α and Notch1/ETBR play important roles in preeclampsia. Hypoxia-induced HIF-1αregulated Notch1/ETBR signaling, thereby modulating invasion and angiogenesis of trophoblast cells. These results shed light on molecular mechanisms of preeclampsia and provide potential targets for preeclampsia therapy.

Issues in the interpretation of serum endothelin levels in preeclampsia

In this paper are discussed reasons to suspect that measurements of serum endothelin levels in women with preeclampsia may not provide accurate estimations of the degree of systemic endothelin receptor activation and reasons to suspect that systemic endothelin receptor saturation studies should provide such estimations more accurately.

Endothelin-1 traps as a potential therapeutic tool: from diabetes to beyond?

There is substantial research on the vasoactive peptide endothelin (ET)-1 in physiology, as well as in pathology. In fact, pathologically elevated levels of ET-1 have been found in several disease states, such as various cardiovascular diseases, different cancers, some neurodegenerative disorders, as well as in diabetes. Here, we describe and discuss ET-1, its importance in different diseases, and the potential therapeutic effects of ET-traps in the treatment of these diseases. Previous in vitro and in vivo research (in the diabetes disease space) demonstrated that ET-traps potently and significantly prevent the induction of different markers of diabetes-related pathology. This included induction of extracellular matrix (ECM) proteins (collagen 4α1 and fibronectin), which are pathologically elevated in diabetes. The ET-traps prevented induction of these and brought a significant return to non-diabetic levels. We also discuss the merits of using ET-traps over the currently used endothelin receptor antagonists (ERAs) and previously used therapeutic antibodies.

Endoplasmic reticulum stress disrupts lysosomal homeostasis and induces blockade of autophagic flux in human trophoblasts

Pregnancy is a stress factor culminating into mild endoplasmic reticulum (ER) stress, which is necessary for placental development. However, excessive or chronic ER stress in pre-eclamptic placentas leads to placental dysfunction. The precise mechanisms through which excessive ER stress impacts trophoblasts are not well understood. Here, we showed that ER stress reduces the number of lysosomes, resulting in inhibition of autophagic flux in trophoblast cells. ER stress also disrupted the translocation of lysosomes to the surface of trophoblast cells, and inhibited lysosomal exocytosis, whereby the secretion of lysosomal-associated membrane protein 1 (LAMP1) into culture media was significantly attenuated. In addition, we found that serum LAMP1 and beta-galactosidase levels were significantly decreased in pre-eclampsia patients compared to normal pregnant women, potentially indicating lysosomal dysfunction through ER stress in pre-eclamptic placentas. Thus, we demonstrated that excessive ER stress essentially disrupts homeostasis in trophoblasts in conjunction with autophagy inhibition by lysosomal impairment.

Endothelin type B receptor interacts with the 78-kDa glucose-regulated protein

Endothelin (ET)-1 is involved in the vascular system, cell proliferation and apoptosis. ET receptors consist of ET type A receptor (ET_A R) and ET type B receptor (ET_B R). ET_A R and ET_B R generally exhibit opposite responses, although many exceptions exist. In the present study, we attempted to identify ET_A R- or ET_B R-specific binding proteins to understand the differences in ET_A R- and ET_B R-mediated responses after ET-1 stimulation. The 78-kDa glucose-regulated protein (GRP78) showed a stronger binding affinity towards ET_B R than towards ET_A R. Moreover, GRP78 overexpression promoted ET_B R-mediated ERK activation and GRP78 silencing suppressed ET_B R-mediated ERK activation. Furthermore, ET_B R can localize GRP78 to the cell periphery. These results suggest that the interaction of ET_B R with GRP78 affects ERK activation and GRP78 localization.

The potential contribution of stromal cell-derived factor 2 (SDF2) in endoplasmic reticulum stress response in severe preeclampsia and labor-onset

Endoplasmic reticulum (ER) stress occurs when the protein folding machinery in the cell is unable to cope with newly synthesized proteins, which results in an accumulation of misfolded proteins in the ER lumen. In response, the cell activates a cellular signaling pathway known as the Unfolded Protein Response (UPR), aiming to restore cellular homeostasis. Activation and exacerbation of the UPR have been described in several human pathologies, including cancer and neurological disorders, and in some gestational diseases such as preeclampsia and gestational diabetes. This review explores the participation of stromal cell-derived factor 2 (SDF2) in UPR pathways, shows new information and discusses its exacerbation regarding protein expression in severe preeclampsia and labor, both of which are associated with ER stress.

Role of Endoplasmic Reticulum Stress in Proinflammatory Cytokine-Mediated Inhibition of Trophoblast Invasion in Placenta-Related Complications of Pregnancy

Shallow extravillous trophoblast (EVT) invasion is central to the pathophysiology of many pregnancy complications. Invasion is mediated partially by matrix metalloproteinases (MMPs). MMP-2 is highly expressed in early pregnancy. MMP activity can be regulated by proinflammatory cytokines, which also induce endoplasmic reticulum (ER) stress in other cells. We investigated whether proinflammatory cytokines regulate MMP-2 activity through ER stress response pathways in trophoblast before exploring potential regulatory mechanisms. There was increased immunoreactivity of heat shock 70-kDa protein 5, also known as 78-kDa glucose regulated protein, in cells of the placental bed, including EVTs, in cases of early-onset preeclampsia compared with normotensive controls. Treating EVT-like JEG-3 and HTR8/SVneo cells with ER stress inducers (tunicamycin and thapsigargin) suppressed MMP2 mRNA and protein expression, secretion, and activity and reduced their invasiveness. A cocktail of proinflammatory cytokines (IL-1β, tumor necrosis factor-α, and interferon-γ) suppressed MMP-2 activity in JEG-3 cells and was accompanied by activation of the PKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2A (EIF2A) arm of the ER stress pathway. Knockdown of ATF4, a downstream transcriptional factor of the PERK-EIF2A pathway, by small interference RNA, restored MMP2 expression but not cellular proteins. However, suppression of EIF2A phosphorylation with a PERK inhibitor, GSK2606414, under ER stress, restored MMP-2 protein. ER stress regulates MMP-2 expression at both the transcriptional and translational levels. This study provides the first mechanistic linkage by which proinflammatory cytokines may modulate trophoblast invasion through ER stress pathways.

Endothelin-1 traps potently reduce pathologic markers back to basal levels in an in vitro model of diabetes

Background

Diabetes mellitus is a group of metabolic disorders in which there are high blood glucose levels over a prolonged period. Diabetes is one of many diseases associated with pathologically elevated levels of endothelin (ET)-1. We have recently proposed the development of ET-traps, which are an antibody - based fusion protein that potently bind and sequester pathologically elevated levels of endothelin-1.

Methods

We constructed ET-traps that were found to be very potent binders to ET-1, with a K_D of 32.5ρM. We then treated human retinal microvascular endothelial cells (HRMECs), which are an in vitro model of glucose induced cellular damage, with 10 nM ET-1 or high glucose levels (25 mM).

Results

In this study, we investigated the effects of our ET-trap constructs on the expression levels of both collagen 4α1 and fibronectin, which are both important pathologic markers in diabetes. Treating HRMECs with 10 nM ET-1 or 25 mM glucose significantly induces the expression of the ECM proteins fibronectin and collagen 4α1, as is found in chronic diabetic complications; Incubation of the cells with the ET-traps significantly prevented the increased expression of fibronectin and collagen 4α1 back to basal levels. This was found with both mRNA and protein expression levels of the two ECM proteins.

Conclusion

Our results provide the first evidence of the efficacy of ET-traps in reducing pathologic markers in an in vitro model (of diabetes). Further research is warranted to determine the efficacy of ET-traps as a therapeutic tool for diabetes, which is a major public health burden around the world.

A novel neuroregenerative approach using ET(B) receptor agonist, IRL-1620, to treat CNS disorders

Endothelin B (ET(B)) receptors present in abundance the central nervous system (CNS) have been shown to have significant implications in its development and neurogenesis. We have targeted ET(B) receptors stimulation using a highly specific agonist, IRL-1620, to treat CNS disorders. In a rat model of cerebral ischemia intravenous administration IRL-1620 significantly reduced infarct volume and improved neurological and motor functions compared to control. This improvement, in part, is due to an increase in neuroregeneration. We also investigated the role of IRL-1620 in animal models of Alzheimer's disease (AD). IRL-1620 improved learning and memory, reduced oxidative stress and increased VEGF and NGF in Abeta treated rats. IRL-1620 also improved learning and memory in an aged APP/PS1 transgenic mouse model of AD. These promising findings prompted us to initiate human studies. Successful chemistry, manufacturing and control along with mice, rat and dog toxicological studies led to completion of a human Phase I study in healthy volunteers. We found that a dose of 0.6 microg/kg of IRL-1620 can be safely administered, three times every four hours, without any adverse effect. A Phase II clinical study with IRL-1620 has been initiated in patients with cerebral ischemia and mild to moderate AD.

Temporal changes of the endothelin system in human cytotrophoblasts during the first trimester of pregnancy

The first trimester of pregnancy is characterized by continuous proliferation, invasion and differentiation of cytotrophoblasts. These processes are precisely controlled both, in space and time by molecules such as endothelin-1 (ET-1). ET-1 is expressed in human first trimester trophoblast and is known to stimulate cytotrophoblast proliferation through endothelin A and B receptor subtypes (ET(A) and ET(B)), and cytotrophoblast invasion through ET(B). However, temporal changes of the ET system during the first trimester of pregnancy have not been previously studied. This study tested the hypothesis that ET-1 release, ET(A) and ET(B) expression are increased towards the end of the first trimester of pregnancy (weeks 10-12 vs. weeks 6-9), resulting in increased cytotrophoblast proliferation and invasion. Tissue samples were obtained from 17 surgical pregnancy interruptions (week 6-9: n=9; week 10-12: n=8). After cytotrophoblast isolation, the invasive and proliferative phenotypes were immune-separated by an alpha(6)-integrin antibody. Both proliferative and invasive cytotrophoblasts were cultured separately on plastic or Matrigel for 24 h. ET-1 release into the culture medium of both cytotrophoblast subtypes was measured by radioimmunoassay. ET(A) and ET(B) mRNA expression was measured by RT-PCR, and the ET-1 effect on cytotrophoblast proliferation and invasion was determined using proliferation and invasion assays, respectively. ET-1 release increased from early to late first trimester of pregnancy in both proliferative (1.8-4.5 fold) and invasive cytotrophoblasts (9.3-28 fold), especially when cultured on Matrigel. This was paralleled by less ET(B) mRNA on invasive cytotrophoblasts independent of the time period in first trimester, whereas ET(A) expression was similar on proliferative an invasive cytotrophoblasts. Proliferation and invasion of cytotrophoblasts under control conditions decreased from early to late first trimester. ET-1 stimulated both processes at both periods with the most pronounced effect (7-fold) on invasion in late first trimester. The ET-1/ET-receptor system changes between weeks 6-9 and 10-12 in pregnancy. Our data suggest an autocrine and endocrine ET-1 effect, which is stronger in late than in early first trimester of pregnancy paralleled by different stimulatory effects on trophoblast invasion and proliferation. In general, this suggests time as an additional effector of the critical processes governing placental development in the first trimester of human pregnancy.

Preeclamptic plasma stimulates the expression of miRNAs, leading to a decrease in endothelin-1 production in endothelial cells

Preeclampsia is a major cause of maternal and fetal morbidity and mortality worldwide. It is a multisystem pregnancy syndrome characterized by general endothelial dysfunction caused mainly by plasma factors and debris in endothelial cells. It is widely accepted that endothelin-1 (ET-1) is involved in the pathophysiology of preeclampsia, and so it is of interest to ascertain whether the ET-1 gene (EDN1) can be targeted with tools such as miRNAs. Therefore, we investigated the relationship between the expression of miRNAs that putatively target EDN1 (and so affect ET-1 levels) in HUVECs incubated with plasma from preeclamptic women. EDN1 expression and ET-1 levels in HUVECs incubated with plasma from women with preeclampsia were similar to those in plasma from healthy pregnant women. Expression of miRNAs let-7a, -7b, and -7c, and to a lesser degree 125a and 125b, was increased in preeclampsia. Expression of miRNAs of the let-7 family was significantly negatively correlated with ET-1 levels in preeclampsia. Transfection of the preeclampsia cultures with mimic miRNA let-7 decreased ET-1 levels. Our findings show that preeclamptic plasma stimulates the expression of miRNAs in HUVECs, leading to a decrease in ET-1levels, which suggests that therapeutic miRNAs may aid in the management of preeclampsia.

Neurohumoral and Endothelial Responses to Heated Water-Based Exercise in Resistant Hypertensive Patients

BACKGROUND

The neurohumoral and endothelial responses to the blood pressure (BP) lowering effects of heated water-based exercise (HEx) in resistant hypertension (HT) patients remain undefined.

METHODS AND RESULTS

We investigated these in 44 true resistant HT patients (age 53.3±0.9 years, mean±SEM). They were randomized and allocated to 2 groups, 28 to a HEx training protocol, which consisted of callisthenic exercises and walking in a heated pool for 1 h, three times weekly for 12 weeks and 16 patients to a control group maintaining their habitual activities. Measurements made before and after 12 weeks of HEx included clinic and 24-h BP, plasma levels of nitric oxide, endothelin-1, aldosterone, renin, norepinephrine and epinephrine, as well as peak V̇O2, and endothelial function (reactive hyperemia). After 12 weeks of HEx patients showed a significant decrease in clinic and 24-h systolic and diastolic BPs. Concomitantly, nitric oxide increased significantly (from 25±8 to 75±24 μmol/L, P<0.01), while endothelin-1 (from 41±5 to 26±3 pg/mL), renin (from 35±4 to 3.4±1 ng/mL/h), and norepinephrine (from 720±54 to 306±35 pg/mL) decreased significantly (P<0.01). Plasma aldosterone also tended to decrease, although not significantly (from 101±9 to 76±4 pg/mL, P=NS). Peak V̇O2increased significantly after HEx (P<0.01), while endothelial function was unchanged. No significant change was detected in the control group.

CONCLUSIONS

The BP-lowering effects of HEx in resistant HT patients were accompanied by a significant reduction in the marked neurohumoral activation characterizing this clinical condition.

Endothelin receptor-specific control of endoplasmic reticulum stress and apoptosis in the kidney

Endothelin-1 (ET-1) promotes renal damage during cardiovascular disease; yet, the molecular mechanisms involved remain unknown. Endoplasmic reticulum (ER) stress, triggered by unfolded protein accumulation in the ER, contributes to apoptosis and organ injury. These studies aimed to determine whether the ET-1 system promotes renal ER stress development in response to tunicamycin. ET_B deficient (ET_B def) or transgenic control (TG-con) rats were used in the presence or absence of ET_A receptor antagonism. Tunicamycin treatment similarly increased cortical ER stress markers in both rat genotypes; however, only ET_B def rats showed a 14-24 fold increase from baseline for medullary GRP78, sXBP-1, and CHOP. Pre-treatment of TG-con rats with the ET_A blocker ABT-627 for 1 week prior to tunicamycin injection significantly reduced the ER stress response in cortex and medulla, and also inhibited renal apoptosis. Pre-treatment with ABT-627 failed to decrease renal ER stress and apoptosis in ET_B def rats. In conclusion, the ET-1 system is important for the development of tunicamycin-induced renal ER stress and apoptosis. ET_A receptor activation induces renal ER stress genes and apoptosis, while functional activation of the ET_B receptor has protective effects. These results highlight targeting the ET_A receptor as a therapeutic approach against ER stress-induced kidney injury.

Losartan attenuates aortic endothelial apoptosis induced by chronic intermittent hypoxia partly via the phospholipase C pathway

PURPOSE

Endoplasmic reticulum (ER) stress is known to play key roles in the development of endothelial cell apoptosis induced by chronic intermittent hypoxia (CIH), and the angiotensin II-phospholipase C-inositol-1,4,5-triphosphate (AngII-PLC-IP3) pathway has been demonstrated to induce ER stress. To explore whether the AngII-PLC-IP3 pathway is involved in the vascular damage induced by CIH, we examined whether the AngII-PLC-IP3 pathway is involved in ER stress induced by CIH and whether losartan, a selective angiotensin II type 1 receptor (AT1R) blocker, could suppress endothelial cell apoptosis induced by CIH.

METHODS

Adult male Sprague Dawley rats were subjected to 8 h/day of intermittent hypoxia/normoxia, with or without losartan, a selective AT1R blocker, and/or U73122, a selective PLC inhibitor, for 8 weeks. Endothelial cell apoptosis, ER stress markers, and levels of PLC-γ1 and IP3R expression were determined.

RESULTS

Losartan prevented increases in PLC-γ1 and IP3R protein levels and inhibited ER stress markers induced by CIH. Addition of U73122 reproduced all the protective effects of losartan. Losartan administration before CIH significantly ameliorated CIH-induced endothelial cell apoptosis.

CONCLUSIONS

This study showed that the AngII-PLC-IP3 pathway is involved in ER stress induced by CIH and that pre-losartan administration ameliorates endothelial cell apoptosis following CIH partly via inhibition of the AngII-PLC-IP3 pathway and ER stress.

Understanding Pre-Eclampsia Using Alzheimer's Etiology: An Intriguing Viewpoint

Characterized by hypertension and proteinuria after the 20th week of gestation, pre-eclampsia (PE) is a major cause of maternal, fetal, and neonatal morbidity and mortality. Despite being recognized for centuries, PE still lacks a reliable, early means of diagnosis or prediction, and a safe and effective therapy. We have recently reported that the event of toxic protein misfolding and aggregation is a critical etiological manifestation in PE. Using comparative proteomic analysis of gestational age-matched sera from PE and normal pregnancy, we identified several proteins that appeared to be dysregulated in PE. Our efforts so far have focused on transthyretin (TTR), a transporter of thyroxine and retinol, and amyloid precursor protein whose aggregates were detected in the PE placenta. Based on these results and detection of TTR aggregates in sera from PE patients, we proposed that PE could be a disease of protein misfolding and aggregation. Protein misfolding and aggregation have long been linked with many neurodegenerative diseases such as Alzheimer's disease. However, linkage of protein misfolding and aggregation with the PE pathogenesis is a new and novel concept. This review aims to understand the roles of aggregated proteins in PE using the cues from the Alzheimer's etiology.

The Human Endogenous Protection System against Cell-Free Hemoglobin and Heme Is Overwhelmed in Preeclampsia and Provides Potential Biomarkers and Clinical Indicators

Preeclampsia (PE) complicates 3-8% of all pregnancies and manifests clinically as hypertension and proteinuria in the second half of gestation. The pathogenesis of PE is not fully understood but recent studies have described the involvement of cell-free fetal hemoglobin (HbF). Hypothesizing that PE is associated with prolonged hemolysis we have studied the response of the cell-free Hb- and heme defense network. Thus, we have investigated the levels of cell-free HbF (both free, denoted HbF, and in complex with Hp, denoted Hp-HbF) as well as the major human endogenous Hb- and heme-scavenging systems: haptoglobin (Hp), hemopexin (Hpx), α1-microglobulin (A1M) and CD163 in plasma of PE women (n = 98) and women with normal pregnancies (n = 47) at term. A significant increase of the mean plasma HbF concentration was observed in women with PE. Plasma levels of Hp and Hpx were statistically significantly reduced, whereas the level of the extravascular heme- and radical scavenger A1M was significantly increased in plasma of women with PE. The Hpx levels significantly correlated with maternal blood pressure. Furthermore, HbF and the related scavenger proteins displayed a potential to be used as clinical biomarkers for more precise diagnosis of PE and are candidates as predictors of identifying pregnancies with increased risk of obstetrical complications. The results support that PE pathophysiology is associated with increased HbF-concentrations and an activation of the physiological Hb-heme defense systems.

Endoplasmic reticulum stress signaling in mammalian oocytes and embryos: life in balance

Mammalian oocytes and embryos are exquisitely sensitive to a wide range of insults related to physical stress, chemical exposure, and exposures to adverse maternal nutrition or health status. Although cells manifest specific responses to various stressors, many of these stressors intersect at the endoplasmic reticulum (ER), where disruptions in protein folding and production of reactive oxygen species initiate downstream signaling events. These signals modulate mRNA translation and gene transcription, leading to recovery, activation of autophagy, or with severe and prolonged stress, apoptosis. ER stress signaling has recently come to the fore as a major contributor to embryo demise. Accordingly, agents that modulate or inhibit ER stress signaling have yielded beneficial effects on embryo survival and long-term developmental potential. We review here the mechanisms of ER stress signaling, their connections to mammalian oocytes and embryos, and the promising indications that interventions in this pathway may provide new opportunities for improving mammalian reproduction and health.

Preeclampsia serum-induced collagen I expression and intracellular calcium levels in arterial smooth muscle cells are mediated by the PLC-γ1 pathway

In women with preeclampsia (PE), endothelial cell (EC) dysfunction can lead to altered secretion of paracrine factors that induce peripheral vasoconstriction and proteinuria. This study examined the hypothesis that PE sera may directly or indirectly, through human umbilical vein ECs (HUVECs), stimulate phospholipase C-γ1-1,4,5-trisphosphate (PLC-γ1-IP₃) signaling, thereby increasing protein kinase C-α (PKC-α) activity, collagen I expression and intracellular Ca²⁺ concentrations ([Ca²⁺]_i) in human umbilical artery smooth muscle cells (HUASMCs). HUASMCs and HUVECs were cocultured with normal or PE sera before PLC-γ1 silencing. Increased PLC-γ1 and IP₃ receptor (IP₃R) phosphorylation was observed in cocultured HUASMCs stimulated with PE sera (P<0.05). In addition, PE serum significantly increased HUASMC viability and reduced their apoptosis (P<0.05); these effects were abrogated with PLC-γ1 silencing. Compared with normal sera, PE sera increased [Ca²⁺]_i in cocultured HUASMCs (P<0.05), which was inhibited by PLC-γ1 and IP₃R silencing. Finally, PE sera-induced PKC-α activity and collagen I expression was inhibited by PLC-γ1 small interfering RNA (siRNA) (P<0.05). These results suggest that vasoactive substances in the PE serum may induce deposition in the extracellular matrix through the activation of PLC-γ1, which may in turn result in thickening and hardening of the placental vascular wall, placental blood supply shortage, fetal hypoxia–ischemia and intrauterine growth retardation or intrauterine fetal death. PE sera increased [Ca²⁺]_i and induced PKC-α activation and collagen I expression in cocultured HUASMCs via the PLC-γ1 pathway.

Hypoxic treatment of human dual placental perfusion induces a preeclampsia-like inflammatory response

Preeclampsia is a human pregnancy-specific disorder characterized by a placental pro-inflammatory response in combination with an imbalance of angiogenic factors and clinical symptoms, including hypertension and proteinuria. Insufficient uteroplacental oxygenation in preeclampsia due to impaired trophoblast invasion during placentation is believed to be responsible for many of the molecular events leading to the clinical manifestations of this disease. We investigated the use of hypoxic treatment of the dual placental perfusion system as a model for preeclampsia. A modified perfusion technique allowed us to achieve a mean soluble oxygen tension within the intervillous space (IVS) of 5-7% for normoxia and <3% for hypoxia (as a model for preeclampsia). We assayed for the levels of different inflammatory cytokines, oxidative stress markers, as well as other factors, such as endothelin (ET)-1 that are known to be implicated as part of the inflammatory response in preeclampsia. Our results show a significant increase under hypoxia in the levels of different inflammatory cytokines, including IL-6 (P=0.002), IL-8 (P<0.0001), TNF-α (P=0.032) and IFN-γ (P=0.009) at 360 min in maternal venous samples (n=6). There was also a significant increase in ET-1 levels under hypoxia both on the maternal side at 30 min (P=0.003) and fetal side at 360 min (P=0.036) (n=6). Other markers of oxidative stress, including malondialdehyde and 8-iso-protaglandin F2α (P=0.009) also show increased levels. Overall, these findings indicate that exposure of ex vivo dually perfused placental tissue to hypoxia provides a useful model for mimicking the inflammatory response characteristic of preeclampsia. This would therefore provide a powerful tool for studying and further delineating the molecular mechanisms involved in the underlying pathophysiology of preeclampsia.

The therapeutic potential of antioxidants, ER chaperones, NO and H2S donors, and statins for treatment of preeclampsia

Preeclampsia is a complex multifactorial disease. Placental oxidative stress, a result of deficient spiral artery remodeling, plays an important role in the pathophysiology of preeclampsia. Antiangiogenic factors secreted from malperfused placenta are instrumental in mediating maternal endothelial dysfunction and consequent symptoms of preeclampsia; the mechanism is likely to involve increased ET-1 secretion and reduced NO bioavailability. Therapeutic interventions so far remain only experimental and there is no established remedy for the treatment of preeclampsia. This review concentrates on the evidence for the therapeutic potential of antioxidants, ER chaperones, NO and H2S donors, and statins. These compounds display pleitropic antioxidant, anti-inflammatory, and pro-angiogenic effects in animal and in vitro studies. Although clinical trials on the use of antioxidant vitamins in pregnancy proved largely unsuccessful, the scope for their use still exists given the beneficial cardioprotective effects of antioxidant-rich Mediterranean diet, periconceptual vitamin use and the synergistic effect of vitamin C and L-arginine. Encouraging clinical evidence exists for the use of NO donors, and a clinical trial is underway testing the effect of statins in treatment of preeclampsia. H2S recently emerged as a novel therapeutic agent for cardiovascular disease, and its beneficial effects were also tested in animal models of preeclampsia. It is risky to prescribe any medication to pregnant women on a large scale, and any future therapeutic intervention has to be well tested and safe. Many of the compounds discussed could be potential candidates.

MiR-101 regulates apoptosis of trophoblast HTR-8/SVneo cells by targeting endoplasmic reticulum (ER) protein 44 during preeclampsia

To investigate a possible association between miR-101 and apoptosis of human trophoblast cells mediated by endoplasmic reticulum protein 44 (ERp44) in preeclampsia (PE), we explored the expression of miR-101 in PE placentas (n=30) compared with normotensive pregnant placentas (n=30) and the correlation between miR-101 and ERp44 was also analyzed. Furthermore, both the apoptotic rate of trophoblast cells and the ER stress-induced apoptotic proteins were assayed when the HTR-8/SVneo cells were treated with miR-101 mimics or inhibitors in vitro. We found a lower expression of miR-101 and an inverse correlation between miR-101 and ERp44 protein in PE placentas. Upregulation of miR-101 expression could inhibit trophoblast HTR-8/SVneo cell apoptosis and repress ER stress-induced apoptotic proteins by targeting ERp44 in vitro, whereas inhibition of miR-101 could induce HTR-8/SVneo cell apoptosis. Our findings indicated that overexpression of miR-101 could downregulate ERp44 and suppress apoptosis in trophoblast cells during PE. Therefore, loss of miR-101 expression could contribute to ER stress-induced trophoblast cell apoptosis by targeting ERp44.

Uterine endoplasmic reticulum stress and its unfolded protein response may regulate caspase 3 activation in the pregnant mouse uterus

We have previously proposed that uterine caspase-3 may modulate uterine contractility in a gestationally regulated fashion. The objective of this study was to determine the mechanism by which uterine caspase-3 is activated and consequently controlled in the pregnant uterus across gestation. Utilizing the mouse uterus as our gestational model we examined the intrinsic and extrinsic apoptotic signaling pathways and the endoplasmic reticulum stress response as potential activators of uterine caspase-3 at the transcriptional and translational level. Our study revealed robust activation of the uterine myocyte endoplasmic reticulum stress response and its adaptive unfolded protein response during pregnancy coinciding respectively with increased uterine caspase-3 activity and its withdrawal to term. In contrast the intrinsic and extrinsic apoptotic signaling pathways remained inactive across gestation. We speculate that physiological stimuli experienced by the pregnant uterus likely potentiates the uterine myocyte endoplasmic reticulum stress response resulting in elevated caspase-3 activation, which is isolated to the pregnant mouse myometrium. However as term approaches, activation of an elevated adaptive unfolded protein response acts to limit the endoplasmic reticulum stress response inhibiting caspase-3 resulting in its decline towards term. We speculate that these events have the capacity to regulate gestational length in a caspase-3 dependent manner.

Decreased expression of Wiskott-Aldrich syndrome protein family verprolin-homologous protein 2 may be involved in the development of pre-eclampsia

Wiskott–Aldrich syndrome protein family verprolin-homologous protein 2 (WAVE2) is a protein that mediates actin cytoskeletal reorganization and lamellipodia protrusion formation, which are required for cell migration and invasion. The primary purpose of this study was to determine whether there is an association between reactive oxygen species (ROS) and WAVE2 in pre-eclampsia, and whether WAVE2 expression in trophoblast cells is vulnerable to oxidative stress. This study observed excessive generation of ROS and decreased expression of WAVE2 in pre-eclamptic placentas compared with normotensive controls. Moreover, there was a significant negative correlation between ROS and WAVE2 protein in pre-eclamptic placenta (P < 0.001). An in-vitro model of hypoxia–reoxygenation (H/R) was used to imitate oxidative stress in placental trophoblasts, and it was found that the expression of WAVE2 protein in trophoblasts was decreased after H/R treatment. Additionally, compared with normoxia, decreased cell proliferation, higher cell apoptosis and attenuated cell migration and invasion were detected in trophoblasts exposed to H/R. In conclusion, the findings strongly suggest that excessive oxidative stress can decrease WAVE2 expression in trophoblasts and that the decreased expression of WAVE2 in trophoblast cells may be involved in the development of pre-eclampsia.

Endothelin-1-induced endoplasmic reticulum stress in disease

The accumulation of unfolded proteins in the endoplasmic reticulum (ER) represents a cellular stress induced by multiple stimuli and pathologic conditions. Recent evidence implicates endothelin-1 (ET-1) in the induction of placental ER stress in pregnancy disorders. ER stress has previously also been implicated in various other disease states, including neurodegenerative disorders, diabetes, and cardiovascular diseases, as has ET-1 in the pathophysiology of these conditions. However, to date, there has been no investigation of the link between ET-1 and the induction of ER stress in these disease states. Based on recent evidence and mechanistic insight into the role of ET-1 in the induction of placental ER stress, the following review attempts to outline the broader implications of ET-1-induced ER stress, as well as strategies for therapeutic intervention based around ET-1.

Increased placental phospholipid levels in pre-eclamptic pregnancies

Physiological pregnancy is associated with an increase in lipids from the first to the third trimester. This is a highly regulated response to satisfy energy and membrane demands of the developing fetus. Pregnancy disorders, such as pre-eclampsia, are associated with a dysregulation of lipid metabolism manifesting in increased maternal plasma lipid levels. In fetal placental tissue, only scarce information on the lipid profile is available, and data for gestational diseases are lacking. In the present study, we investigated the placental lipid content in control versus pre-eclamptic samples, with the focus on tissue phospholipid levels and composition. We found an increase in total phospholipid content as well as changes in individual phospholipid classes in pre-eclamptic placental tissues compared to controls. These alterations could be a source of placental pathological changes in pre-eclampsia, such as lipid peroxide insult or dysregulation of lipid transport across the syncytiotrophoblast.

Endothelin-1: a key pathological factor in pre-eclampsia?

Endothelin (ET)-1 has been implicated in a diverse range of signalling events in a wide variety of target tissues. Given its potent vasoactive function and the prevalence of hypertension in pre-eclampsia, there has been extensive research on the role of ET-1 in this disorder. Indeed, ET-1 has been suggested to contribute to hypertension in pre-eclampsia. Recently, ET-1 has also been implicated in the induction of both oxidative stress and endoplasmic reticulum stress in pre-eclampsia; each of which has been proposed to contribute to many of the clinical manifestations of this disorder. ET-1 has been shown to activate key signalling molecules that lead to induction of these stress pathways. The use of ET-receptor antagonists could block oxidative and endoplasmic reticulum stress. Hence, further research into the role of ET-1 in pre-eclampsia may lead to the development of possible strategies to circumvent these stress pathways and the associated pathology that occurs in pre-eclampsia. Endothelin (ET)-1 has been implicated in a diverse range of signalling events in a wide variety of target tissues. Given its potent vasoactive function and the prevalence of hypertension in pre-eclampsia, there has been extensive research on the role of ET-1 in this disorder. Indeed, ET-1 has been suggested to contribute to hypertension in pre-eclampsia. Recently, ET-1 has also been implicated in the induction of both oxidative stress and endoplasmic reticulum stress in pre-eclampsia, each of which has been proposed to contribute to many of the clinical manifestations of this disorder. ET-1 has been shown to activate key signalling molecules that lead to induction of these stress pathways. The use of ET-receptor antagonists could block oxidative and endoplasmic reticulum stress. Hence, further research into the role of ET-1 in pre-eclampsia may lead to the development of possible strategies to circumvent these stress pathways and the associated pathology that occurs in pre-eclampsia.