Reduced expression of 1-cys peroxiredoxin in oxidative stress-induced cataracts

Sulforaphane-Induced Klf9/Prdx6 Axis Acts as a Molecular Switch to Control Redox Signaling and Determines Fate of Cells

Sulforaphane (SFN), an activator of transcription factor Nrf2 (NFE2-related factor), modulates antioxidant defense by Nrf2-mediated regulation of antioxidant genes like Peroxiredoxin 6 (Prdx6) and affects cellular homeostasis. We previously observed that dose levels of SFN are crucial in determining life or death of lens epithelial cells (LECs). Herein, we demonstrated that higher doses of SFN (>6 μM) activated death signaling by overstimulation of Nrf2/ARE (antioxidant response element)-mediated Kruppel-like factor (Klf9) repression of Prdx6 expression, which increased reactive oxygen species (ROS) load and cell death. Mechanistically, Klf9 bound to its repressive Klf9 binding elements (RKBE; 5-C^A/GCCC-3) in the Prdx6 promoter, and repressed Prdx6 transcription. Under the condition of higher dose of SFN, excessive Nrf2 abundance caused death signaling by enforcing Klf9 activation through ARE (5-RTGAYnnnGC-3) in Klf9 promoter that suppress antioxidant genes such as Prdx6 via a Klf9-dependent fashion. Klf9-depletion showed that Klf9 independently caused ROS reduction and subsequent cell survival, demonstrating that Klf9 upregulation caused cell death. Our work revealed the molecular mechanism of dose-dependent altered activity of SFN in LECs, and demonstrated that SFN activity was linked to levels of Nrf2/Klf9/Prdx6 axis. We proposed that in the development of therapeutic interventions for aging/oxidative disorders, combinations of Klf9-ShRNA and Nrf2 inducers may prove to be a promising strategy.

Protective effects of Nigella sativa L. seed extract on lead induced neurotoxicity during development and early life in mouse models

Lead (Pb), a ubiquitous heavy metal and a known neurotoxicant, produces adverse effects on the brain via increased production of reactive oxygen species (ROS) and causes oxidative stress. In this study we examined the neuroprotective effects of the ethanolic extract of Nigella sativa L. seeds on Pb induced oxidative stress in the developing brain of mice. Mouse pups were exposed to low (0.1%) and high (0.2%) doses of Pb from the first day of pregnancy through their mothers (via drinking water) and lactation until post-natal day (PND) 21. The mRNA expression levels of superoxide dismutase (SOD1), peroxiredoxin (Prdx6), amyloid precursor protein (APP) common, APP695 and APP770 were examined in the cortex and hippocampus of the mouse brain excised on PND 21 by semi-quantitative RT-PCR. The free radical scavenging activity of ethanolic Nigella sativa L. extract was assessed by DPPH assay. The results showed that Pb exposure caused a significant decrease in the expression of SOD1, Prdx6 and APP695 and an increase in APP770 in both cortex and hippocampus in a dose dependent manner as compared to the control group. The expression of APP common remained unaltered. Histological assessment of the cortex and hippocampus demonstrated a decrease in the neuronal number and Nissl bodies. The administration of 250 and 500 mg kg-1 ethanolic Nigella sativa L. extract reversed the adverse effects by significantly increasing the expression of SOD1, Prdx6 and APP695 and decreasing the expression of APP770 in both the regions. These results strongly suggest that Nigella sativa L. supplementation greatly improves Pb-induced neurotoxicity in early life and provides neuroprotective and antioxidant potentials.

Sulforaphane reactivates cellular antioxidant defense by inducing Nrf2/ARE/Prdx6 activity during aging and oxidative stress

Upon oxidative stress and aging, Nrf2 (NFE2-related factor2) triggers antioxidant defense genes to defends against homeostatic failure. Using human(h) or rat(r) lens epithelial cells (LECs) and aging human lenses, we showed that a progressive increase in oxidative load during aging was linked to a decline in Prdx6 expression. DNA binding experiments using gel-shift and ChIP assays demonstrated a progressive reduction in Nrf2/ARE binding (-357/-349) of Prdx6 promoter. The promoter (-918) with ARE showed a marked reduction in young vs aged hLECs, which was directly correlated to decreased Nrf2/ARE binding. A Nrf2 activator, Sulforaphane (SFN), augmented Prdx6, catalase and GSTπ expression in dose-dependent fashion, and halted Nrf2 dysregulation of these antioxidants. SFN reinforced Nrf2/DNA binding and increased promoter activities by enhancing expression and facilitating Nrf2 translocalization in nucleus. Conversely, promoter mutated at ARE site did not respond to SFN, validating the SFN-mediated restoration of Nrf2/ARE signaling. Furthermore, SFN rescued cells from UVB-induced toxicity in dose-dependent fashion, which was consistent with SFN's dose-dependent activation of Nrf2/ARE interaction. Importantly, knockdown of Prdx6 revealed that Prdx6 expression was prerequisite for SFN-mediated cytoprotection. Collectively, our results suggest that loss of Prdx6 caused by dysregulation of ARE/Nrf2 can be attenuated through a SFN, to combat diseases associated with aging.

Isolation and characterisation of peroxiredoxin 6 promoter from sheep (Ovis aries)

Introduction: Peroxiredoxin 6 (Prdx6) is a bifunctional protein and a unique 1-Cys Prdx of the peroxiredoxin family. The expression and regulation of Prdx6 are implicated in numerous physiological and pathological processes.

Material and Methods: Eight stepwise truncated DNA fragments obtained from the 5′-flank region of the Prdx6 gene were prepared and subcloned into the pSEAP2-Enhancer vectors. To investigate the transcriptional activity of the truncated DNA fragments, the recombinant plasmids were transfected into the COS-1 cells and the transcriptional activity was measured via assaying the expression of the reporter gene of the secreted alkaline phosphatase.

Results: A 3.4 kb 5′-upstream flank region of the Prdx6 gene was cloned and sequenced. The region from −108 nt to −36 nt of the 5′-flanking region of the Prdx6 gene contained basal transcriptional activity.

Conclusion: This result provides the basis for further studies on the gene regulation of the Prdx6-mediated biological processes and on screening for the transacting factors that interact with cis-acting elements of the Prdx6 gene promoter.

Thioredoxins, glutaredoxins, and peroxiredoxins--molecular mechanisms and health significance: from cofactors to antioxidants to redox signaling

Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and "antioxidants". Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions.

Molecular characterization and expression analysis of six peroxiredoxin paralogous genes in gilthead sea bream (Sparus aurata): insights from fish exposed to dietary, pathogen and confinement stressors

The aim of this work was to underline the physiological role of the antioxidant peroxiredoxin (PRDX) family in gilthead sea bream (Sparus aurata L.), a perciform fish extensively cultured in the Mediterranean area. First, extensive BLAST searches were done on the gilthead sea bream cDNA database of the AQUAMAX European Project (www.sigenae.org/iats), and six contigs were unequivocally identified as PRDX1-6 after sequence completion by RT-PCR. The phylogenetic analysis evidenced three major clades corresponding to PRDX1-4 (true 2-Cyst PRDX subclass), PRDX5 (atypical 2-Cys PRDX subclass) and PRDX6 (1-Cys PRDX subclass) that reflected the present hierarchy of vertebrates. However, the PRDX2 branch of modern fish including gilthead sea bream was related to the monophyletic PRDX1 node rather than to PRDX2 cluster of mammals and primitive fish, which probably denotes the acquisition of novel functions through vertebrate evolution. Transcriptional studies by means of quantitative real-time PCR evidenced a ubiquitous PRDX gene expression that was tissue specific for each PRDX isoform. In a second set of transcriptional studies, liver and head kidney were chosen as target tissues in fish challenged with i) the intestinal parasite Enteromyxum leei, ii) a plant oil (VO) diet with deficiencies in essential fatty acids and iii) prolonged exposure to high-rearing densities. These studies showed that PRDX genes were highly and mostly constitutively expressed in the liver and were not affected by dietary intervention or high density. In contrast, head kidney was highly sensitive to the different experimental challenges: significantly lower values were found for PRDX5 in the three trials, for PRDX6 in parasitized and high density fish and for PRDX1 in parasitized and VO fish. PRDX2, 3 and 5 were decreased only in VO, high density and parasitized animals, respectively. These findings would highlight the role of PRDXs as integrative and highly predictive biomarkers of health and welfare in fish and gilthead sea bream in particular.

A proteomic study using zebra mussels (D. polymorpha) exposed to benzo(α)pyrene: the role of gender and exposure concentrations

It has recently been established that the use of proteomics can be a useful tool in the field of ecotoxicology. Despite the fact that the mussel Dreissena polymorpha is a valuable bioindicator for freshwater ecosystems, the application of a proteomic approach with this organism has not been deeply investigated. To this end, several zebra mussel specimens were subjected to a 7-day exposure of two different concentrations (0.1 and 2 μg L⁻¹) of the model pollutant benzo[α]pyrene (B[α]P). Changes in protein expression profiles were investigated in gill cytosolic fractions from control/exposed male and female mussels using 2-DE electrophoresis. B[α]P bioaccumulation in mussel soft tissue was also assessed to validate exposure to the selected chemical. We evaluated overall changes in expression profiles for 28 proteins in exposed mussels, 16 and 12 of which were, respectively, over- and under-expressed. Surprisingly, the comparative analysis of protein data sets showed no proteins that varied commonly between the two different B[α]P concentrations. Spots of interest were manually excised and analysed by MALDI-TOF/TOF mass spectrometry. The most significant proteins that were identified as altered were related to oxidative stress, signal transduction, cellular structure and metabolism. This preliminary study indicates the feasibility of a proteomic approach with the freshwater mussel D. polymorpha and provides a starting point for similar investigations. Our results confirm the need to increase the number of invertebrate proteomic studies in order to increase the following: their representation in databases and the successful identification of their most relevant proteins. Finally, additional studies investigating the role of gender and protein modulation are warranted.

Peroxiredoxin 6 overexpression attenuates cisplatin-induced apoptosis in human ovarian cancer cells

We examined the involvement of peroxiredoxin 6 (Prdx 6) in providing chemoprotection against cisplatin cytotoxicity in SKOV-3 ovarian cancer cells. Treatment of SKOV-3 cells with cisplatin-induced cytotoxicity that was associated with increased accumulation of intracellular reactive oxygen species (ROS) and apoptosis mediated by proteolytically activated caspase 3 and 9. Overexpression of Prdx 6 protein or exposure to N-acetylcysteine (NAC) reversed the apoptotic effect of cisplatin by reducing ROS levels and suppressing the caspase signaling pathway. These results indicate that targeting Prdx 6 may sensitize cancer cells to ROS-producing therapeutic treatments, such as anticancer drugs and radiation.

Neuroprotective effect of peroxiredoxin 6 against hypoxia-induced retinal ganglion cell damage

Background

The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS)-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC) death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6) plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis.

Results

We have shown that RGCs exposed to hypoxia (1%) or hypoxia mimetic cobalt chloride display reduced expression of PRDX6 with higher ROS expression and activation of NF-κB. These cells undergo apoptosis, while cells with over-expression of PRDX6 demonstrate resistance against hypoxia-driven RGC death. The RGCs exposed to hypoxia either with 1% oxygen or cobalt chloride (0-400 μM), revealed ~30%-70% apoptotic cell death after 48 and 72 h of exposure. Western analysis and real-time PCR showed elevated expression of PRDX6 during hypoxia at 24 h, while PRDX6 protein and mRNA expression declined from 48 h onwards following hypoxia exposure. Concomitant with this, RGCs showed increased ROS expression and activation of NF-κB with IkB phosphorylation/degradation, as examined with H2DCF-DA and transactivation assays. These hypoxia-induced adverse reactions could be reversed by over-expression of PRDX6.

Conclusion

Because an abundance of PRDX6 in cells was able to attenuate hypoxia-induced RGC death, the protein could possibly be developed as a novel therapeutic agent acting to postpone RGC injury and delay the progression of glaucoma and other disorders caused by the increased-ROS-generated death signaling related to hypoxia.

Protein expression profiling of lens epithelial cells from Prdx6-depleted mice and their vulnerability to UV radiation exposure

Oxidative stress is one of the causative factors in progression and etiology of age-related cataract. Peroxiredoxin 6 (Prdx6), a savior for cells from internal or external environmental stresses, plays a role in cellular signaling by detoxifying reactive oxygen species (ROS) and thereby controlling gene regulation. Using targeted inactivation of the Prdx6 gene, we show that Prdx6-deficient lens epithelial cells (LECs) are more vulnerable to UV-triggered cell death, a major cause of skin disorders including cataractogenesis, and these cells display abnormal protein profiles. PRDX6-depleted LECs showed phenotypic changes and formed lentoid body, a characteristic of terminal cell differentiation and epithelial-mesenchymal transition. Prdx6(-/-) LECs exposed to UV-B showed higher ROS expression and were prone to apoptosis compared with wild-type LECs, underscoring a protective role for Prdx6. Comparative proteomic analysis using fluorescence-based difference gel electrophoresis along with mass spectrometry and database searching revealed a total of 13 proteins that were differentially expressed in Prdx6(-/-) cells. Six proteins were upregulated, whereas expression of seven proteins was decreased compared with Prdx6(+/+) LECs. Among the cytoskeleton-associated proteins that were highly expressed in Prdx6-deficient LECs was tropomyosin (Tm)2beta. Protein blot and real-time PCR validated dramatic increase of Tm2beta and Tm1alpha expression in these cells. Importantly, Prdx6(+/+) LECs showed a similar pattern of Tm2beta protein expression after transforming growth factor (TGF)-beta or H(2)O(2) treatment. An extrinsic supply of PRDX6 could restore Tm2beta expression, demonstrating that PRDX6 may attenuate adverse signaling in cells and thereby maintain cellular homeostasis. Exploring redox-proteomics (Prdx6(-/-)) and characterization and identification of abnormally expressed proteins and their attenuation by PRDX6 delivery should provide a basis for development of novel therapeutic interventions to postpone ROS-mediated abnormal signaling deleterious to cells or tissues.

Peroxiredoxin 6 fails to limit phospholipid peroxidation in lung from Cftr-knockout mice subjected to oxidative challenge

Oxidative stress plays a prominent role in the pathophysiology of cystic fibrosis (CF). Despite the presence of oxidative stress markers and a decreased antioxidant capacity in CF airway lining fluid, few studies have focused on the oxidant/antioxidant balance in CF cells. The aim of the current study was to investigate the cellular levels of reactive oxygen species (ROS), oxidative damage and enzymatic antioxidant defenses in the lung of Cftr-knockout mice in basal conditions and as a response to oxidative insult.

The results show that endogenous ROS and lipid peroxidation levels are higher in Cftr^−/− lung when compared to wild-type (Cftr^+/+) in basal conditions, despite a strong enzymatic antioxidant response involving superoxide dismutases, glutathione peroxidases and peroxiredoxin 6 (Prdx6). The latter has the unique capacity to directly reduce membrane phospholipid hydroperoxides (PL-OOH). A dramatic increase in PL-OOH levels in Cftr^−/− lung consecutive to in vivo oxidative challenge by paraquat (PQ) unmasks a susceptibility to phospholipid peroxidation. PQ strongly decreases Prdx6 expression in Cftr^−/− mice compared to Cftr^+/+. Similar results were obtained after P. aeruginosa LPS challenge. Two-dimensional gel analysis of Prdx6 revealed one main molecular form in basal conditions and a PQ-induced form only detected in Cftr^+/+ lung. Mass spectrometry experiments suggested that, as opposed to the main basal form, the one induced by PQ is devoid of overoxidized catalytic Cys47 and could correspond to a fully active form that is not induced in Cftr^−/− lung. These results highlight a constitutive redox imbalance and a vulnerability to oxidative insult in Cftr^−/− lung and present Prdx6 as a key component in CF antioxidant failure. This impaired PL-OOH detoxification mechanism may enhance oxidative damage and stress-related signaling, contributing to an exaggerated inflammatory response in CF lung.

Molecular cloning and characterization of peroxiredoxin 6 from Chinese mitten crab Eriocheir sinensis

Peroxiredoxin is a superfamily of antioxidative proteins that play important roles in protecting organisms against the toxicity of reactive oxygen species (ROS). In this study, the full-length cDNA encoding peroxiredoxin 6 (designated EsPrx6) was cloned from Chinese mitten crab Eriocheir sinensis by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EsPrx6 was of 1076 bp, containing a 5' untranslated region (UTR) of 69 bp, a 3' UTR of 347 bp with a poly (A) tail, and an open reading frame (ORF) of 660 bp encoding a polypeptide of 219 amino acids with the predicted molecular weight of 24 kDa. The conserved Prx domain, AhpC domain and the signature of peroxidase catalytic center identified in EsPrx6 strongly suggested that EsPrx6 belonged to the 1-Cys Prx subgroup. Quantitative real-time RT-PCR was employed to assess the mRNA expression of EsPrx6 in various tissues and its temporal expression in haemocytes of crabs challenged with Listonella anguillarum. The mRNA transcript of EsPrx6 could be detected in all the examined tissues with highest expression level in hepatopancreas. The expression level of EsPrx6 in haemocytes was down-regulated after bacterial challenge and significantly decreased compared to the control group at 12h. As time progressed, the expression level began to increase but did not recover to the original level during the experiment. The results suggested the involvement of EsPrx6 in responses against bacterial infection and further highlighted its functional importance in the immune system of E. sinensis.

Oxidative stress, lens gap junctions, and cataracts

The eye lens is constantly subjected to oxidative stress from radiation and other sources. The lens has several mechanisms to protect its components from oxidative stress and to maintain its redox state, including enzymatic pathways and high concentrations of ascorbate and reduced glutathione. With aging, accumulation of oxidized lens components and decreased efficiency of repair mechanisms can contribute to the development of lens opacities or cataracts. Maintenance of transparency and homeostasis of the avascular lens depend on an extensive network of gap junctions. Communication through gap junction channels allows intercellular passage of molecules (up to 1 kDa) including antioxidants. Lens gap junctions and their constituent proteins, connexins (Cx43, Cx46, and Cx50), are also subject to the effects of oxidative stress. These observations suggest that oxidative stress-induced damage to connexins (and consequent altered intercellular communication) may contribute to cataract formation.

Isoform-specific downregulation of peroxiredoxin in human failing myocardium

Peroxiredoxins (Prx) are a family of antioxidant thioredoxin or glutathione dependent peroxidases. The major functions of Prx comprise modulation of signalling cascades that apply hydrogen peroxide (H(2)O(2)) and cellular protection against oxidative stress. Nothing is known about Prx isoforms in human myocardium. We investigated the protein expression of Prx isoforms 1-6 in human non-failing (NF, donor hearts, n=6, male, age: 53.3+/-2.1 years) and failing myocardium (DCM, orthotopic heart transplantation, dilated cardiomyopathy, n=15, male, 57.0+/-1.7 years). In addition, we performed immunohistochemical stainings and measured Prx 4 mRNA expression levels (RNAse protection assay). The protein expression of Prx 1-2 was similar in NF and DCM. The protein expression of Prx 3-6 and the mRNA-expression of Prx 4 were decreased in DCM. Immunohistochemical analyses provided evidence that all Prx isoforms are present in cardiomyocytes and endothelial cells. Whereas Prx 1-5 staining was more pronounced in endothelial cells, Prx6 staining was more evident in cardiomyocytes. This study provides evidence that Prx are differentially regulated in DCM. The selective downregulation of peroxiredoxin 3-6 isoforms may point towards a subcellular specific dysregulation of the antioxidative defence during the development of DCM.

Positive correlation between peripheral blood granulocyte oxidative status and level of anxiety in mice

Oxidative stress is involved in many acute and chronic diseases including cancer, cardiovascular disorders and neurodegenerative diseases. We studied the relationship between the level of intracellular reactive oxygen species in peripheral granulocytes and the estimated anxiety level of mice using the behavioral light/dark choice test. Our results indicate a linear and significant relationship between the intracellular redox status of peripheral blood granulocytes and different parameters of anxiety-related behavior including latency time (R(2)=0.737, P<0.001), cumulative time spent in the lit box (R(2)=0.612, P<0.01) and number of entries into the lit box (R(2)=0.661, P<0.01). These results suggest a positive relationship between peripheral oxidative status and level of anxiety in mice.

Expression of 1-cys peroxiredoxin in the corneal wound-healing process

PURPOSE

To study the regulation by mitomycin C (MMC) of 1-cys peroxiredoxin (Prx) expression during the corneal wound-healing process and its induction pathway in cultured bovine keratocytes (BKs).

METHODS

Rat corneas were excised at 4 hours, 12 hours, 1 day, 3 days, and 7 days after photorefractive keratectomy (PRK). Expression of 1-cys Prx in the corneas was examined by Northern blot and immunoblot analyses. Cultured BKs were exposed to 0.02% MMC for 5 minutes and maintained under normal culture conditions for different time periods. Subsequently, levels of 1-cys Prx and extracellular signal-regulated kinase (ERK)1/2 expression were measured by immunoblot analysis using polyclonal 1-cys Prx, ERK1/2, or phospho-ERK1/2 antibodies. To inhibit ERK1/2 activation, the BKs were pretreated with 50 micromol/mL PD98059 for 1 hour before MMC exposure and incubated in complete medium with or without PD98059 for 24 hours. MMC-induced cytotoxicity was determined by colorimetric cell-counting kit-8 assay.

RESULTS

Increased levels of 1-cys Prx expression were seen in wounded rat corneas at 12 hours after injury and reached the highest level between 1 and 3 days, during which time active proliferation occurred. Induction of 1-cys Prx expression was obvious in proliferating BKs stimulated by growth factors. MMC treatment in cultured BKs resulted in increased expression of 1-cys Prx and phospho-ERK1/2 in a time-dependent manner. Treatment with 50 micromol/mL PD98059 significantly inhibited the active ERK1/2 and 1-cys Prx expression induced by MMC, leading to synergistic cytotoxicity in the BKs.

CONCLUSION

1-Cys Prx may function as an important enzyme in cell proliferation during the postinjury corneal wound-healing process. Furthermore, the induction of 1-cys Prx expression through the ERK1/2 signaling pathway may contribute to cellular defense against cytotoxic agents, thus playing an important role in cell survival.

Investigating transcriptional regulation of Prdx6 in mouse liver cells

Prdx6, a unique member of the peroxiredoxin family of antioxidants, is highly expressed in liver and protects cells from oxidative damage by reducing H2O2 and various lipid peroxides. We investigated the transcriptional regulation of Prdx6 in the H2.35 mouse hepatocyte cell line and sought to determine the mechanism of basal and induced expression. We found that Prdx6 expression is down-regulated upon serum deprivation and subsequently induced in a time-dependent manner in response to KGF, TNF-alpha, dexamethasone, and H2O2. Inhibitors of both PKC and MEK largely prevented Prdx6 induction by KGF and, to a lesser extent, TNF-alpha. Interestingly, inhibition of NF-kappaB led to a marked increase in Prdx6 regulation in the absence or presence of inducers, suggesting a normal role for NF-kappaB in Prdx6 suppression. Using reporter constructs from the mouse gene, we found that the first 160 bp of the proximal promoter was sufficient for low levels of expression, and expression increased sixfold with 1200 bp of the proximal promoter. These regions were not, however, sufficient to mediate up-regulation by the known Prdx6 inducers in our system. Together, these data support multiple pathways of Prdx6 regulation and reveal important promoter regions that mediate its transcriptional regulation.

Proteomic Analysis on the Alteration of Protein Expression in the Placental Villous Tissue of Early Pregnancy Loss

Early pregnancy loss is the most common complication of human reproduction. Given the complexities of early development, it is likely that many mechanisms are involved. Knowledge of differences in protein expression in parallel profiling is essential to understand the comprehensive pathophysiological mechanism underlying early pregnancy loss. To identify proteins with different expression profiles related to early pregnancy loss, we applied a proteomic approach and performed two-dimensional gel electrophoresis (2-DE) on six placental villous tissues from patients with early pregnancy loss and six from normal pregnant women, followed by comparison of the silver-stained 2-DE profiles. It was found that 13 proteins were downregulated and 5 proteins were upregulated significantly (P < 0.05) in early pregnancy loss as determined by spot volume. Among them, 10 downregulated and 2 upregulated spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Anomalies of these proteins, including three principal antioxidant enzymes (copper/zinc-superoxide dismutase, peroxiredoxin 3, and thioredoxin-like 1 protein), S100 calcium binding protein, galectin-1, chorionic somatomammotropin hormone 1, transthyretin, fas inhibitory molecule, eukaryotic translation elongation factor, RNA-binding protein, ubiquitin-conjugating enzyme E2N, and proteasome beta-subunit, indicate widespread failure in cell regulations and processes such as antioxidative defense, differentiation, cell proliferation, metabolism, apoptosis, transcription, and proteolysis in early pregnancy loss. This study has identified several proteins that are associated with placentation and early development, shedding a new insight into the proteins that may be potentially involved in the pathophysiological mechanisms underlying early pregnancy loss.