• The Korean Journal of Zoology
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• v.35 no.4
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• pp.456-465
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• 1992

The 94 KDa glucose-resulsted Protein (SH 94), one of stress Proteins, is a Ca2+-binding protein in the endoplasmic reticulum (ER). In this study, the possible effect of Ca2+ on the native conformation of grp 94 was examined. When the purified grp 94 was analyzed by Sel filtration in the presence of either EGTA or CaCl2, it was eluted with apparent molecular weight (MW) of 100 KDa in both cases. When similarly analyzed with microtome or cell Ivsate, however, srp 94 was eluted with apparent IW of 200 KDa in the presence of E6TA, while with apparent MW of 100 KDa in the presence of CaCl2, indicating possible association of grp 94 with one or more other proteins in the absence of CaCl2. Consequently, immunoprecipitation with anti-grp 94 was carried out to determine which proteins specifically interact with grp 94. It is sho%un that srp 94 may interact, in a Ca2+_dependent manner. with other proteins including BiP (grp 78) which is also a stress protein in the ER.

• BMB Reports
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• v.47 no.8
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• pp.445-450
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• 2014

Glucose regulated protein 78 (GRP78) is frequently highly expressed in tumor cells, contributing to the acquisition of several phenotypic cancer hallmarks. GRP78 expression is also positively correlated with tumor metastasis, and promotes hepatocellular carcinoma cell invasion via increasing cell motility, however, other mechanisms involving the prometastatic roles of GRP78 remain to be elucidated. Here we report that forced GRP78 expression promotes colon cancer cell migration and invasion through upregulating MMP-2, MMP-9 and especially uPA production. These effects of GRP78 are mediated by enhancing the activation of ${\beta}$-catenin signaling. Interestingly, we identify that GRP78 interacts with uPA both in the cells and in the culture medium, suggesting that GRP78 protein is likely to directly facilitate uPA secretion via protein-protein interaction. Taken together, our findings demonstrate for the first time that besides stimulation of cell motility, GRP78 can act by increasing proteases production to promote tumor cell invasion.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7245-7249
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• 2014

Glucose regulated protein 78 (GRP78) is usually recognized as a chaperone in the endoplasmic reticulum. However, increasing evidence indicates that GRP78 can be translocated to the cell surface, acting as a signaling receptor for a variety of ligands. Since little is known about the secretion of GRP78 and its role in the progression of colon cancer we here focused on GRP78 from colon cancer cells, and purified GRP78 protein mimicking the secreted GRP78 was able to utilize cell surface GRP78 as its receptor, activating downstream PI3K/Akt and Wnt/${\beta}$-catenin signaling and promote colon cancer cell proliferation. Our study revealed a new mode of action of autocrine GRP78 in cancer progression: secreted GRP78 binds to cell surface GRP78 as its receptor and activates intracellular proliferation signaling.

• The Korean Journal of Zoology
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• v.39 no.1
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• pp.47-53
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• 1996

We examined the expression of the heat shock proteins (HSPs) and glucose-regulated proteins (GRPs) during phorbol 1 2-myristate 1 3-acetate (PMA)-induced megakaryocytic differentiation of human er"'throleukemia K562 cells. PMA-treated K562 cells showed a cell growth arrest and alteration in morphology and patterns of gpllIa and c-myc expression, characteristic of megakaryocytic differentiation. During the megakaryocytic differentiation, HSP9OA, HSP9OB, and HSP28 mRNA and protein levels markedly decreased, while GRP78/B and GRP94 mRNA levels were enhanced. On the other hand, HSP7OA and HSP7OB mRNA levels were reduced, but HSP7O protein levels were not changed by PMA treatment. These results suggest specific roles for the HSPs and GRPs in K562 cell proliferation and megakaryocic differentiation.tion.

• Journal of Aquaculture
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• v.20 no.4
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• pp.205-211
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• 2007

Stress-inducible proteins may function in part as molecular chaperones, protecting cells from damage due to various stresses and helping to maintain homeostasis. We examined the mRNA expression patterns of a 68-kDa heat shock protein (HSP68) and 78-kDa glucose-regulated protein (GRP78) in relation to physiological changes in Pacific oyster Crassostrea gigas under osmotic stress. Expression of HSP68 and GRP78 mRNA in the gill significantly increased until 48 h in a hypersaline environment (HRE) and 72 h in a hyposaline environment (HOE), and then decreased. Osmolality and the concentrations of $Na^+$, $Cl^-$, and $Ca^{2+}$ in the hemolymph of HRE oysters significantly increased until 72 h (the highest value) and then gradually decreased; in HOE oysters, these values significantly decreased until 72 h (the lowest value), and then increased. These results suggest that osmolality and $Na^+$, $Cl^-$, and $Ca^{2+}$ concentrations were stabilized by HSP68 and GRP78, and indicate that these two stress-induced proteins play an important role in regulating the metabolism and protecting the cells of the Pacific oysters exposed to salinity changes.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.733-738
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• 2020

Glucose deprivation and hypoxia frequently occur in solid tumor cells, including pancreatic cancer cells. Glucose deprivation activates the unfolded protein response (UPR) and causes the up-regulation of glucose-regulated protein 78 (GRP78). Induction of GRP78 has been shown to protect cancer cells. Therefore, shutting down of GRP78 expression may be a novel strategy in anticancer drug development. Based on this understanding, a screening system established for anticancer agents that exhibit selective cytotoxicity on pancreatic cancer cells under glucose-deprived conditions. To test this hypothesis, the new compounds isolated, pancastatin A (PST-A) and B (PST-B), from Ponciri Fructus. PST-A and B were identified as glabretal triterpenoid moieties by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopic methods. PST-A and B suppressed the accumulation of the UPR hallmark gene, GRP78, during glucose deprivation. Furthermore, PST-A and B showed selective cytotoxicity on PANC-1 pancreatic cancer cells under glucose deprivation. Interestingly, PST-A and B had no effect on these cells under normal growth conditions. Our results suggest that PST-A and B act as novel therapeutic agents to induce selective cell death in glucose-deprived pancreatic cancer cells.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.8
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• pp.3517-3522
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• 2015

Background: Glucose regulated protein 78 (GRP78) is a type of molecular chaperone. It is a possible candidate protein that contributes to development of drug resistance. We first examined the involvement of GRP78 in chemotherapy-resistance in human ovarian cancer cell. Materials and Methods: The expression of GRP78 mRNA and protein were examined by RT-PCR and western blotting, respectively, in human ovarian cancer cells line (HO-8910). Sensitivity of HO-8910 to paclitaxel was determined with methyl thiazolyl tetrazolium (MTT). Suppression of GRP78 expression was performed using specific small-interfering RNA (siRNA) in HO-8910 cells, and cell apoptosis was assessed by flow cytometry. Statistical analysis was performed using the SPSS 15.0 statistical package. Results: HO-8910 cells, with high basal levels of GRP78, exhibited low sensitivity to paclitaxel. The mRNA and protein levels of GRP78 were dramatically decreased at 24h, 48h and 72h after transfection and the sensitivity to paclitaxel was increased when the GRP78 gene was disturbed by specific siRNA transfection. Conclusions: The results suggested that high GRP78 expression might be one of the molecular mechanisms causing resistance to paclitaxel, and therefore siRNA of GRP78 may be useful in tumor-specific gene therapy for ovarian cancer.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.6
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• pp.345-351
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• 2011

High glucose leads to physio/pathological alterations in diabetes patients. We investigated collagen production in human gingival cells that were cultured in high concentrations of glucose. Collagen synthesis and secretion were increased when the cells were exposed to high concentrations of glucose. We examined endoplasmic reticulum (ER) stress response because glucose metabolism is related to ER functional status. An ER stress response including the expression of glucose regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), inositol requiring enzyme alpha (IRE-$1{\alpha}$) and phosphoreukaryotic initiation factor alpha (p-eIF-$2{\alpha}$) was activated in the presence of high glucose. Activating transcription factor 4 (ATF-4), a downstream protein of p-eIF-$2{\alpha}$ as well as a transcription factor for collagen, was also phosphorylated and translocalized into the nucleus. The chemical chaperone 4-PBA inhibited the ER stress response and ATF-4 phosphorylation as well as nuclear translocation. Our results suggest that high concentrations of glucose-induced collagen are linked to ER stress and the associated phosphorylation and nuclear translocation of ATF-4.

• Biomolecules & Therapeutics
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• v.26 no.5
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• pp.464-473
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• 2018

Cripto is a small glycosylphosphatidylinositol-anchored signaling protein that can detach from the anchored membrane and stimulate proliferation, migration, differentiation, vascularization, and angiogenesis. In the present study, we demonstrated that Cripto positively affected proliferation and survival of mesenchymal stem cells (MSCs) without affecting multipotency. Cripto also increased expression of phosphorylated janus kinase 2 (p-JAK2), phosphorylated signal transducer and activator of transcription 3 (p-STAT3), 78 kDa glucose-regulated protein (GRP78), c-Myc, and cyclin D1. Notably, treatment with an anti-GRP78 antibody blocked these effects. In addition, pretreatment with STAT3 short interfering RNA (siRNA) inhibited the increase in p-JAK2, c-Myc, cyclin D1, and BCL3 levels caused by Cripto and attenuated the pro-survival action of Cripto on MSCs. We also found that incubation with Cripto protected MSCs from apoptosis caused by hypoxia or $H_2O_2$ exposure, and the level of caspase-3 decreased by the Cripto-induced expression of B-cell lymphoma 3-encoded protein (BCL3). These effects were sensitive to down-regulation of BCL3 expression by BCL3 siRNA. Finally, we showed that Cripto enhanced expression levels of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and hepatocyte growth factor (HGF). In summary, our results demonstrated that Cripto activated a novel biochemical cascade that potentiated MSC proliferation and survival. This cascade relied on phosphorylation of JAK2 and STAT3 and was regulated by GRP78. Our findings may facilitate clinical applications of MSCs, as these cells may benefit from positive effects of Cripto on their survival and biological properties.

• Development and Reproduction
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• v.21 no.4
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• pp.407-415
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• 2017

In the present study, we investigated the role of binding immunoglobulin protein/glucose-regulated protein, 78-kDa (BIP/GRP78)-regulated endoplasmic reticulum (ER)-stress on meiotic maturation and cumulus cells expansion in porcine cumulus-oocyte complexes (COCs). Previously, it has been demonstrated that unfolded protein response (UPR)-related genes, such as molecules involved in ER-stress defense mechanisms, were expressed in matured oocytes and cumulus cells during in vitro maturation (IVM) of porcine oocytes. However, BIP/GRP78-mediated regulation of ER stress in porcine oocytes has not been reported. Firstly, we observed the effects of knockdown of BIP/GRP78 (an UPR initiation marker) using porcine-specific siRNAs (#909, #693, and #1570) on oocyte maturation. Among all siRNAs, siRNA #693 significantly reduced the protein levels of UPR marker proteins (BIP/GRP78, ATF4, and P90ATF6) in porcine COCs observed by Western blotting and immunofluorescence analysis. We also observed that the reduction of BIP/GRP78 levels by siRNA#693 significantly inhibited the meiotic maturation of oocytes (siRNA #693: $32.5{\pm}10.1%$ vs control: $77.8{\pm}5.3%$). In addition, we also checked the effect of ER-stress inhibitors, tauroursodeoxycholic acid (TUDCA, $200{\mu}M$) and melatonin ($0.1{\mu}M$), in BIP/GRP78-knockdown oocytes. TUDCA and melatonin treatment could restore the expression levels of ER-stress marker proteins (BIP/GRP78, $p-eIF2{\alpha}$, $eIF2{\alpha}$, ATF4, and P90ATF6) in siRNA #693-transfected matured COCs. In conclusion, these results demonstrated that BIP/GRP78-mediated regulation of UPR signaling and ER stress plays an important role in in vitro maturation of porcine oocytes.