Identification and functional characterization of an endoplasmic reticulum oxidoreductin 1-α gene in Litopenaeus vannamei

Identification and functional analysis of endoplasmic reticulum oxidoreductase 1 (ERO1) from the green mud crab Scylla paramamosain: The first evidence of ERO1 involved in invertebrate immune response

Endoplasmic reticulum oxidoreductase 1 (ERO1) is an important mediator in regulating disulfide bond formation and maintaining endoplasmic reticulum homeostasis. Its activity is transcriptionally regulated by the unfolded protein response (UPR) in the endoplasmic reticulum, which is known to be essential in immunity. However, whether ERO1 is involved in innate immunity in invertebrates remains unclear. In the present study, two subtypes of ERO1 from Scylla paramamosain were first identified and characterized. Sequence analysis revealed the conserved ERO1 domain and the oxidative capacity assay verified the oxidative capacity of SpERO1 recombinant protein. Moreover, SpERO1s were found to be ubiquitously expressed in all the tested tissues, with the highest expression observed in hemocytes. Two SpERO1s exhibited distinct expression patterns in response to Vibrio alginolyticus and White Spot Syndrome Virus (WSSV). Importantly, the downregulation of the expression of immune factors upon bacterial challenge in SpERO1-silenced crabs was observed. These results provided an initial foundation for further investigations into the role of ERO1 in the innate immunity of invertebrates.

Proteomic analysis of individual giant freshwater prawn, Macrobrachium rosenbergii, growth retardants

"Iron prawn" is a condition of severe growth retardation that fishers call. The giant river prawn (Macrobrachium rosenbergii) is a commercially important species contains high protein content and functional nutrients. However, no proteomic information is available for this species. We performed the shotgun 2DLC-MS/MS proteomic analysis of the total protein from "iron prawn". Total 19,758 peptides corresponding to 2613 high-confidence proteins were identified. These proteins range in size from 40 to 70 kDa. KEGG analysis revealed that the largest group consisting total 102 KEGG pathway proteins comparing the "iron prawn" with the normal prawn. Additionally, 7, 11, 1, 6, and 5 commercially important enzymes were found in the eyestalk, liver, muscle, ovary, and testis, respectively. The functions of these differently expressed enzymes include immune system action against pathogens, muscle contraction, digestive system metabolism, cell differentiation, migration, and apoptosis in the severe growth retardation of "iron prawn". Our work provides insight into the understanding of the formation mechanism of "iron prawn".

ERO1α inhibits cell apoptosis and regulates steroidogenesis in mouse granulosa cells

ER oxidoreduclin 1α (ERO1α), an oxidase that exists in the ER, participates in protein folding and secretion and inhibiting apoptosis, and regulates tumor progression, which is a novel factor of poor cancer prognosis. However, the other physiological functions of ERO1α remain undiscovered. Although our preliminary results of this study indicated that ERO1α revealed the robust expression in ovary, especially in granulosa cells, the role of ERO1α in follicular development is not well known. Therefore, the aims of the present study were to explore the role of ERO1α and the possible mechanisms in regulating cell apoptosis and steroidogenesis in ovarian granulosa cells. ERO1α was mainly localized in granulosa cells and oocytes in the adult ovary by immunohistochemistry. Western blot analysis showed that the expression of ERO1α was highest at oestrous stage during the estrous cycle. The effect of ERO1α on cell apoptosis and steroidogenesis was detected by transduction of ERO1α overexpression and knockdown lentiviruses into primary cultured granulosa cells. Flow cytometry analysis showed that ERO1α decreased granulosa cells apoptosis. Western bolt and RT-qPCR analysis found that ERO1α increased the ratio of BCL-2/BAX, and decreased BAD and Caspase-3 expression. ELISA analysis showed that ERO1α enhanced estrogen (E2) secretion. Western bolt and RT-qPCR analysis found that ERO1α increased StAR, CYP11A1, 3β-HSD, CYP17A1, and CYP19A1 expression, and decreased CYP1B1 expression. Furthermore, Western bolt analysis found that ERO1αincreased PDI and PRDX 4 expression, and activated the PI3K/AKT/mTOR signaling pathway through increasing the phosphorylation of AKT and P70 S6 kinase. In summary, these results suggested that ERO1α might play an anti-apoptotic role and regulate steroidogenesis in granulosa cells, at least partly, via activation of the PI3K/AKT/mTOR signaling pathway.

Expression of endoplasmic reticulum oxidoreductase 1-α in cholangiocarcinoma tissues and its effects on the proliferation and migration of cholangiocarcinoma cells

Abstract

Endoplasmic reticulum oxidoreductase 1-α (ERO1A) is a kind of hypoxia-induced endoplasmic reticulum oxidase that regulates translation and folding of oxidized proteins. This study aimed to explore the clinicopathological significance of ERO1A and the effect on the biological behavior of cholangiocarcinoma (CCA) cells.

Methods

Immunohistochemical staining was used to detect the expression of ERO1A, carcinoembryonic antigen (CEA), and carbohydrate antigen 19–9 (CA19-9) in cholangiocarcinoma. Immunofluorescence staining was performed to detect the subcellular localization of ERO1A in CCA cells. The expression of ERO1A in CAA cells after depletion or overexpression was verified by Western blot assay. Then, the effect of ERO1A on proliferation in CCA cells was verified by MTT assay and colony formation assay. Wound healing assays and migration assays were performed to detect the effect of ERO1A on cell migration ability. Finally, we explored the role of ERO1A in EMT and Akt/mTOR signaling pathway.

Results

In this study, our data demonstrated that ERO1A, CEA, and CA19-9 were expressed in cholangiocarcinoma tissues, and the positive rates were 95%, 95%, and 55%, respectively. The high expression of ERO1A is associated with clinical stage and pathological stage of CCA. In vitro data indicate that deletion of ERO1A can inhibit the proliferation and migration of CCA cells and vice versa. In addition, ERO1A has been shown to be closely related to EMT and Akt/mTOR pathways.

Conclusion

In summary, we found that high expression of ERO1A is associated with poor prognosis in patients, and ERO1A can promote the proliferation and migration of CCA cells. In conclusion, ERO1A can be used as an independent biomarker for predicting the prognosis of CCA.

Effects of environmental stress on shrimp innate immunity and white spot syndrome virus infection

The shrimp aquaculture industry is plagued by disease. Due to the lack of deep understanding of the relationship between innate immune mechanism and environmental adaptation mechanism, it is difficult to prevent and control the diseases of shrimp. The shrimp innate immune system has received much recent attention, and the functions of the humoral immune response and the cellular immune response have been preliminarily characterized. The role of environmental stress in shrimp disease has also been investigated recently, attempting to clarify the interactions among the innate immune response, the environmental stress response, and disease. Both the innate immune response and the environmental stress response have a complex relationship with shrimp diseases. Although these systems are important safeguards, allowing shrimp to adapt to adverse environments and resist infection, some pathogens, such as white spot syndrome virus, hijack these host systems. As shrimp lack an adaptive immune system, immunization therapy cannot be used to prevent and control shrimp disease. However, shrimp diseases can be controlled using ecological techniques. These techniques, which are based on the innate immune response and the environmental stress response, significantly reduce the impact of shrimp diseases. The object of this review is to summarize the recent research on shrimp environmental adaptation mechanisms, innate immune response mechanisms, and the relationship between these systems. We also suggest some directions for future research.

Hypermethylation of endoplasmic reticulum disulfide oxidase 1α leads to trophoblast cell apoptosis through endoplasmic reticulum stress in preeclampsia

Abnormal trophoblast cell apoptosis is implicated in the pathogenesis of pregnancy-related disorders including preeclampsia (PE), and endoplasmic reticulum (ER) stress has been considered as a novel pathway in the regulation of cell apoptosis. In this study, we observed that both apoptosis and ER stress are triggered in trophoblast cells under hypoxia as well as in the placenta of PE rats. Quantitative polymerase chain reaction and Western blot analysis showed that the expression of endoplasmic reticulum disulfide oxidase 1α (ERO1α) is suppressed in trophoblast cells under hypoxia due to the hypermethylation of the ERO1α promoter region, and the inhibition of ERO1α expression plays an important role in ER stress and trophoblast cell apoptosis. Furthermore, we found that DNA methyltransferase 1 (DNMT1) is a key methyltransferase for DNA methylation in the regulation of ERO1α expression, and the binding level of DNMT1 to the ERO1α promoter is markedly elevated under hypoxia although DNMT1 expression is inhibited by hypoxia, suggesting that the binding level of DNMT1 to the ERO1α promoter region rather than the DNMT1 expression level contributes to the hypermethylation of ERO1α. Taken together, these results demonstrate that the hypermethylation of ERO1α mediated by increased binding of DNMT1 to the ERO1α promoter leads to trophoblast cell apoptosis through ER stress in the placenta of PE rats, which shed insight into the etiology of PE and might present a validated therapeutic target for the treatment of PE.

Identification and functional characterization of unfolded protein response transcription factor ATF6 gene in kuruma shrimp Marsupenaeus japonicus

Activating transcription factor 6 (ATF6) pathway is the key branch of unfolded protein response (UPR). In this study, a homolog of ATFα from Marsupenaeus japonicus (MjATF6) was identified using genome sequencing and characterized, so as to investigate the role of ATF6 pathway in anti-viral immunity of M. japonicus. The cDNA of MjATF6 obtained was 1008 bp in length, with an open reading frame (ORF) of 849bp, which had encoded a putative of 283 amino acid proteins. Results of qRT-PCR showed that MjATF6 was distributed in all the six tested tissues, with the higher expression level being seen in hemocytes and hepatopancreas. Furthermore, MjATF6 expression would be up-regulated from 1 day to 7 day under white spot syndrome virus (WSSV) challenge. In comparison, RNA interference-induced MjATF6 knockdown had resulted in a lower 7-day cumulative mortality of M. japonicus in the presence of WSSV infection. Additionally, our results also revealed that less VP28 mRNA was extracted from hemocytes or hepatopancreas of MjATF6 knockdown shrimp than that from the control. Taken together, these results have confirmed that ATF6 pathway is vital for WSSV replication, and that UPR in M. japonicus may facilitate WSSV infection.

Litopenaeus vannamei activating transcription factor 6 alpha gene involvement in ER-stress response and white spot symptom virus infection

A previous study found that inositol-requiring enzyme-1-X-box binding protein 1 (IRE1-XBP1) pathway and the protein kinase RNA (PKR)-like ER kinase-eIF2α (PERK-eIF2α) pathway of shrimp play roles in the unfolded protein response (UPR). And they also be proved that was involved in white spot symptom virus (WSSV) infection. Yet the functions of the third branch in shrimp UPR are still unclear. In this study, we showed that upon UPR activation, activating transcription factor 6 alpha (LvATF6α) of Litopenaeus vannamei was cleaved and transferred from the cytoplasm to the nucleus in 293T cells, indicating that the ATF6 pathway in shrimp is also a branch of UPR. Furthermore, LvATF6α could reduce the apoptosis rate of Drosophila Schneider 2 (S2) cells treated with actinomycin, and knock-down expression of LvATF6α increased the apoptosis rate of shrimp hemocytes. In vivo testing revealed that the short from LvATF6α (LvATF6α-s) was obviously increased after UPR activation or WSSV infection, indicating that the ATF6 pathway was activated in L. vannamei gills under such circumstances. Moreover, knock-down expression of LvATF6α could reduce the cumulative mortality and WSSV copy number in WSSV-infected shrimp. Further study revealed that WSSV may profit from shrimp ATF6 pathway activation in two aspects. First, LvATF6α-s significantly upregulated the expression of the WSSV genes (wsv023, wsv045, wsv083, wsv129, wsv222, wsv249, and wsv343). Second, LvATF6α-s inhibited apoptosis by negatively regulating the apoptosis signal-regulating kinase 1 - (c-Jun N-terminal kinase) pathway. All of these evidences suggested that the ATF6 pathway is a member of the L. vannamei UPR, and it is also engaged in WSSV infection.

Expression of ERO1L in gastric cancer and its association with patient prognosis

The present study aimed to assess the expression of endoplasmic reticulum oxidoreductin-1-like (ERO1L) in gastric cancer and determine its association with patient prognosis. A total of 105 patients with gastric cancer undergoing radical gastrectomy were selected for the current study. Gastric cancer tissues (the observation group) and normal gastric tissue adjacent to the carcinoma (the control group) were resected from patients. Levels of ERO1L mRNA and protein in tumor tissues and adjacent tissues were detected using reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry. Patients were divided into two groups: A positive group and negative group, according to the expression of ERO1. The expression of ERO1L in gastric cancer and its association with patient prognosis was analyzed. Levels of ERO1 mRNA and protein in gastric cancer were significantly higher than those of adjacent tissues (P<0.05). Immunohistochemical analysis demonstrated that there were 22 patients exhibiting negative expression of ERO1L and 83 patients exhibiting positive expression of ERO1L. The cumulative recurrence rates over 3 years in patients with positive expression of ERO1L were significantly higher than in patients with negative expression of ERO1L (P<0.05); the cumulative survival rates over 3 years in patients with positive expression of ERO1L were significantly lower than those of patients with negative expression of ERO1L (P<0.05). Thus, the current study determined that ERO1L was highly expressed in gastric cancer tissue. The high expression of ERO1L was associated with adverse prognoses in patients with gastric cancer. ERO1L may therefore be a therapeutic target for the prevention of gastric cancer.

Wsv023 interacted with Litopenaeus vannamei γ-tubulin complex associated proteins 2, and decreased the formation of microtubules

A previous study found the key transcription factor of Litopenaeus vannamei PERK-eIF2α pathway cyclic AMP-dependent transcription factor 4 (LvATF4) was involved in the transcriptional regulation of white spot syndrome virus (WSSV) gene wsv023. Knocked-down expression of LvATF4 reduced the viral copy number and the cumulative mortality of WSSV-infected shrimp. These results suggested that wsv023 may be critical to WSSV infection but the precise function of wsv023 was still unknown. By using co-immunoprecipitation and pull-down assays, we show that wsv023 interacts with L. vannamei gamma complex-associated protein 2 (LvGCP2), which is the core protein of the γ-tubulin small complex. Knocked-down, the wsv023 gene significantly reduced the copy number of WSSV in L. vannamei muscle, as well as the cumulative mortality of infected shrimp. And PERK-eIF2α pathway inhibition also showed reduced virus copy number and abrogated shrimp mortality. Furthermore, overexpression of wsv023 inhibited the formation of microtubules in 293T cells. Flow cytometry revealed that WSSV infection similarly decreased the formation of microtubules in L. vannamei haemocytes. These findings suggested that wsv023 plays a role in microtubule organization in host cells, which in turn may be beneficial to WSSV.

Ammonia exposure induces oxidative stress, endoplasmic reticulum stress and apoptosis in hepatopancreas of pacific white shrimp (Litopenaeus vannamei)

Ammonia is one of major environmental pollutants in the aquatic system that poses a great threat to the survival of shrimp. In the present study, the mRNA expression of endoplasmic reticulum (ER) stress marker and unfolded protein response (UPR) related genes, as well as the change of redox enzyme and apoptosis were investigated in hepatopancreas of the pacific white shrimp, Litopenaeus vannamei after the exposure of 20 mg L(-1) total ammonia nitrogen (TAN). Compared with the control group, the superoxide dismutase (SOD) activity in hepatopancreas decreased significantly (p < 0.05) at 96 h, whereas the malonyldialdehyde (MDA) concentration increased significantly (p < 0.05). The mRNA expression levels of ER stress marker-immunoglobulin heavy chain binding protein (Bip) gene and key UPR related genes including activating transcription factor 4 (ATF4) and the spliced form of X box binding protein 1 (XBP1) increased significantly (p < 0.05) in hepatopancreas at 96 h after exposure to ammonia. In addition, apoptosis was observed obviously in the hepatopancreas of L. vannamei after exposure to ammonia by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The results indicated that ammonia exposure could induce oxidative stress, which further caused ER stress and apoptosis in hepatopancreas of L. vannamei.