• The Korean Journal of Zoology
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• v.38 no.2
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• pp.167-176
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• 1995

Glucose-regulated proteins (grp's), srp94 3nd grp78/BiP, are a group of stress proteins which are highly synthesized in cells exposed to a variety of stressful agents including tunicamycin 3nd Ca2+ ionophore. Grp78/BiP is hon to function as a molecular chaperone which regulates the folding and assembly of secretory or membrane proteins, but the biological function of grp941 remains to be elucidated. In this study, we have examined the intracellular distribution of grV's and the function of srp94. Grp's are resident in the endoplasmic reticulum (ERI 3nd a specific sequence (Lys-Asp-Glu-Leu) at their C-terminus is known to be responsible for their retention within the ER. However, it has been unclear whether upon disturbance of cellular Caa+ homeostasis by the Ca2+ ionophore, grp94 is retained within the ER or secreted into the medium. In this study, we showed that in the presence of C3a+ ionophore, grp94 and gif78/BiP are present in the cells, mainly within the ER. We have also investigated whether grp94 might function as a molecular chaperone. Here we showed that in the immunoglobulin (Ig)-secreting hvbridom3 cells, grp94 transientlY interacts with fully glycosylated Is heavy chain, suggesting that grpg94 may be involved in facilitating the folding and assembly of Ig heavy chains.

• 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.

• Journal of Life Science
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• v.9 no.1
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• pp.76-83
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• 1999

Mammalial expression vectors containing GRP94, BiP, ERp72, and PDI, were introduced into FRTL5 cells. Transfected cells were selected by neomycin resistance for exogenously overexpressed proteins in the ER. The use of a reducible cross-linker, DSP, markedly improved the ability to detect noncovalent interactions of PDI, BiP and GRP94 with newly-synthesized thyroglobulin. Under normal conditions, GRP94 was found to associate transiently with early Tg folding intermediates, displaying interaction kinetics similar to those reported for another ER chaperones of BiP.

• BMB Reports
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• v.57 no.4
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• pp.188-193
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• 2024

Gastric cancer (GC), a leading cause of cancer-related mortality, remains a significant challenge despite recent therapeutic advancements. In this study, we explore the potential of targeting cell surface glucose-regulated protein 94 (GRP94) with antibodies as a novel therapeutic approach for GC. Our comprehensive analysis of GRP94 expression across various cancer types, with a specific focus on GC, revealed a substantial overexpression of GRP94, highlighting its potential as a promising target. Through in vitro and in vivo efficacy assessments, as well as toxicological analyses, we found that K101.1, a fully human monoclonal antibody designed to specifically target cell surface GRP94, effectively inhibits GC growth and angiogenesis without causing in vivo toxicity. Furthermore, our findings indicate that K101.1 promotes the internalization and concurrent downregulation of cell surface GRP94 on GC cells. In conclusion, our study suggests that cell surface GRP94 may be a potential therapeutic target in GC, and that antibody-based targeting of cell surface GRP94 may be an effective strategy for inhibiting GRP94-mediated GC growth and angiogenesis.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.460-469
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• 2017

Heat shock proteins (HSPs) are induced as a self-defense mechanism of cells when exposed to various external stresses, such as high fever, infection, free radicals, and heavy metals. They affect the prognosis in the process of tumor formation. HSP is classified into four families: HSP27, HSP60, HSP90, and HSP100, depending on molecular weight. Heat shock protein 90 (HSP90), a molecular chaperone, plays an important role in the cellular protection against various stressful stimuli and in the regulation of cell cycle progression and apoptosis. In the present study, we assessed the differential expression of HSP90 family proteins in non-small cell lung cancer (NSCLC), and the correlation of their expression levels with clinicopathologic factors and patient survival rates. The result of this study can be summarized as follows; $HSP90{\alpha}$ showed higher expression in patients with no lymphovascular invasion (p=0.014). $HSP90{\beta}$ showed a higher expression of squamous cell carcinoma (p=0.003), and an over expression of glucose-related protein (GRP94) was significantly associated with poor differentiation (p=0.048). However, none of the HSP90 proteins showed a significant association with the survival status in patients with NSCLC. This study also indicates that $HSP90{\alpha}$ might contribute more to the carcinogenesis of NSCLC than $HSP90{\beta}$, and GRP94 and isoform selectivity should be considered when HSP90 inhibitors are studied or utilized in the treatment of NSCLC.

• Biomolecules & Therapeutics
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• v.15 no.4
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• pp.240-244
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• 2007

Cigarette smoking causes serious health problems in humans, especially if smoking habits are established during their adolescence. Nicotine is known to mutate DNA and interfere with apoptosis. Apoptosis is considered as a potent defense mechanism against cellular damaging agents. This study aims to investigate the effect of nicotine on the progression of apoptosis induced under ER stress conditions using four different established cell lines: HEK293, 3T3-L1, C2C12, and HepG2. When treated with nicotine, the progression of apoptosis was notably inhibited in the four cell lines according to the assays of caspase-3 activation and DNA fragmentation. In ER-stressed cells, nicotine appears to inhibit the progression of apoptosis in a concentration-dependent manner. When cells were treated with nicotine prior to ER stress, GRP94 level significantly increased compared to other ER stress markers of PDI and GRP78. This observation suggests that the inhibitory effect of nicotine may results from up-regulation of GRP94, an anti-apoptotic chaperone, under nicotine treatment. Taken together, the present study strongly implies that nicotine may inhibit apoptosis, caused by prolonged ER stress, based on promotion of GRP94 expression.

• Journal of Life Science
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• v.23 no.8
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• pp.1050-1056
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• 2013

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia throughout the world. The bacteria invade through lung tissue and cause sepsis, shock, and serious sequelae, including rheumatic fever and acute glomerulonephritis. However, the molecular mechanism associated with pneumonia's penetration of lung tissue and invasion of the blood stream are still unclear. We attempted to investigate the host cell response at protein levels to S. pneumoniae D39 invasion using human lung cancer epithelial cells, A549. Streptococcus pneumoniae D39 began to change the morphology of A549 cells to become round with filopodia at 2 hours post-infection. A549 cell proteins obtained at each infection time point were separated by SDS-PAGE and analyzed using MALDI-TOF. We identified several endoplasmic reticulum (ER) resident proteins such as Grp94 and Grp78 and mitochondrial proteins such as ATP synthase and Hsp60 that increased after S. pneumoniae D39 infection. Cytosolic Hsc70 and Hsp90 were, however, identified to decrease. These proteins were also confirmed by Western blot analysis. The identified ER resident proteins were known to be induced during ER stress signaling. These/ data, therefore, suggest that S. pneumoniae D39 infection may induce ER stress.

• 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.

• Biomolecules & Therapeutics
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• v.17 no.2
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• pp.162-167
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• 2009

Adipocytes undergo adipocyte stress in the excessive presence of lipid. Adipocyte stress accompanies the typical signs of endoplasmic reticulum (ER) stress: unfolded protein response and overexpression of molecular chaperones. Apoptotic induction in adipocytes is known as a good strategy for treating obesity. The drug "tunicamycin" was tested for its therapeutic potential in inducing apoptosis on differentiating adipocytes of 3T3-L1. When the 3T3-L1 cells, stimulated for adipogenesis, were treated with tunicamycin, they showed typical ER stress symptoms. Despite progression in ER stress, however, the differentiated 3T3-L1 hardly proceeded to apoptosis based on the CHOP protein expression and FACS analysis. This is very different from C2C12, the myogenic counterpart of 3T3-L1, which showed significant apoptosis along with ER stress. This study also characterizes a potential mechanism whereby adipocyte may avoid apoptosis to sustain the pathological state of obesity. The level of GRP94 expression significantly upholds in 3T3-L1 under tunicamycin treatment compared to preadipocytes and C2C-12. When GRP94 expression was inhibited by siRNA, 3T3-L1 showed a higher level of CHOP expression compared to C2C12 cells. In conclusion, adipocytes exert an anti-apoptotic mechanism under ER stress caused by tunicamycin; thus, apoptotic induction in adipocyte is not a viable anti-obesity option. The unusual level of GRP94 may serve as a key role whereby adipocytes reach to the obesity level circumventing the apoptosis.

• BMB Reports
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• v.32 no.3
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• pp.311-316
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• 1999

Studies in adipocytes indicate that secretion of active lipoprotein lipase (LPL) was strictly regulated by a quality control system in the endoplasmic reticulum (ER). However, there has been no report about the ER chaperones participating in the folding and assembly of LPL. Many chaperones are known to bind unfolded proteins and dissociate from them through the ATP-hydrolyzing reaction. In this study, putative ER chaperones for LPL were determined by affinity chromatography using denatured LPL as an affinity ligand and elution with ATP. BiP, grp94, calreticulin, and another 50 kDa K-D-E-L protein in the ER of rat adipose tissue were bound to denatured LPL and eluted by ATP. Calnexin was bound to denatured LPL; however, it was not eluted by ATP but by acetic acid. These results indicate that, at least, BiP, grp94, calreticulin, calnexin, and the unidentified 50 kDa protein might act as putative chaperones for the proper folding and assembly of LPL in ER.