Characterization and Mechanism of Stress-induced Translocation of 78-Kilodalton Glucose-regulated Protein (GRP78) to the Cell Surface

Tsai, Yuan-Li; Zhang, Yi; Tseng, Chun-Chih; Stanciauskas, Ramunas; Pinaud, Fabien; Lee, Amy

doi:10.1074/jbc.m114.618736

Cited by 146 publications

(159 citation statements)

References 58 publications

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“…Alternately, while GRP78 is involved in JEV binding, MHC-I may be involved in virus internalization, similar to what has been reported for coxsackievirus A9 (27). A recent study has shown that GRP78 anchors on the cell membrane via interactions with other proteins and that its translocation mechanism is cell context dependent (38). GRP78 has been reported to interact with diverse proteins, such as voltage-dependent anion channel (46) and the DnaJ-like protein MTJ-1 (28).…”

Section: Discussionmentioning

confidence: 74%

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GRP78 Is an Important Host Factor for Japanese Encephalitis Virus Entry and Replication in Mammalian Cells

Nain

Mukherjee

Karmakar

et al. 2017

J Virol

126

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Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is the leading cause of viral encephalitis in Southeast Asia with potential to become a global pathogen. Here, we identify glucose-regulated protein 78 (GRP78) as an important host protein for virus entry and replication. Using the plasma membrane fractions from mouse neuronal (Neuro2a) cells, mass spectroscopy analysis identified GRP78 as a protein interacting with recombinant JEV envelope protein domain III. GRP78 was found to be expressed on the plasma membranes of Neuro2a cells, mouse primary neurons, and human epithelial Huh-7 cells. Antibodies against GRP78 significantly inhibited JEV entry in all three cell types, suggesting an important role of the protein in virus entry. Depletion of GRP78 by small interfering RNA (siRNA) significantly blocked JEV entry into Neuro2a cells, further supporting its role in virus uptake. Immunofluorescence studies showed extensive colocalization of GRP78 with JEV envelope protein in virus-infected cells. This interaction was also confirmed by immunoprecipitation studies. Additionally, GRP78 was shown to have an important role in JEV replication, as treatment of cells post-virus entry with subtilase cytotoxin that specifically cleaved GRP78 led to a substantial reduction in viral RNA replication and protein synthesis, resulting in significantly reduced extracellular virus titers. Our results indicate that GRP78, an endoplasmic reticulum chaperon of the HSP70 family, is a novel host factor involved at multiple steps of the JEV life cycle and could be a potential therapeutic target.IMPORTANCE Recent years have seen a rapid spread of mosquito-borne diseases caused by flaviviruses. The flavivirus family includes West Nile, dengue, Japanese encephalitis, and Zika viruses, which are major threats to public health with potential to become global pathogens. JEV is the major cause of viral encephalitis in several parts of Southeast Asia, affecting a predominantly pediatric population with a high mortality rate. This study is focused on identification of crucial host factors that could be targeted to cripple virus infection and ultimately lead to development of effective antivirals. We have identified a cellular protein, GRP78, that plays a dual role in virus entry and virus replication, two crucial steps of the virus life cycle, and thus is a novel host factor that could be a potential therapeutic target.

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Section: Discussionmentioning

confidence: 74%

“…GRP78 localization on the cell membrane occurs via interactions with other proteins, and its translocation mechanism is cell type dependent (38). The protein has been shown to be a part of the receptor complex, along with major histocompatibility class I (MHC-I) for coxsackievirus A9 entry (27).…”

Section: Resultsmentioning

confidence: 99%

GRP78 Is an Important Host Factor for Japanese Encephalitis Virus Entry and Replication in Mammalian Cells

Nain

Mukherjee

Karmakar

et al. 2017

J Virol

126

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“…Although GRP78 translocation have been studied mainly in cancer cell lines and have been found to be cell context-dependent (Tsai et al, 2015), there exist some common details for its mechanism of action. GRP78 can be translocated and anchored to the cell surface by binding to the ER-co-chaperone HTJ-1/MTJ-1 (Birukova et al, 2014; Figure 1).…”

Section: Grp78 a Very Important Protein With Multiple Functions In Mmentioning

confidence: 99%

“…A recent study using a combination of biochemical, mutational, FACS, and single molecule super-resolution imaging approaches, reports that GRP78 mainly exists as a peripheral protein on plasma membrane via interaction with other cell surface proteins including glycosylphos-phatidylinositol-anchored proteins since it lacks a true transmembrane domain (Tsai et al, 2015). In addition, the authors discovered that cell-surface GRP78 expression requires its substrate binding activity but is independent of ATP binding.…”

Section: Grp78 a Very Important Protein With Multiple Functions In Mmentioning

confidence: 99%

GRP78 at the Centre of the Stage in Cancer and Neuroprotection

2017

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The 78-kDa glucose-regulated protein GRP78, also known as BiP and HSP5a, is a multifunctional protein with activities far beyond its well-known role in the unfolded protein response (UPR) which is activated after endoplasmic reticulum (ER) stress in the cells. Most of these newly discovered activities depend on its position within the cell. GRP78 is located mainly in the ER, but it has also been observed in the cytoplasm, the mitochondria, the nucleus, the plasma membrane, and secreted, although it is dedicated mostly to engage endogenous cytoprotective processes. Hence, GRP78 may control either UPR and macroautophagy or may activated phosphatidylinositol 3-kinase (PI3K)/AKT pro-survival pathways. GRP78 influences how tumor cells survive, proliferate, and develop chemoresistance. In neurodegeneration, endogenous mechanisms of neuroprotection are frequently insufficient or dysregulated. Lessons from tumor biology may give us clues about how boosting endogenous neuroprotective mechanisms in age-related neurodegeneration. Herein, the functions of GRP78 are revealed at the center of the stage of apparently opposite sites of the same coin regarding cytoprotection: neurodegeneration and cancer. The goal is to give a comprehensive and critical review that may serve to guide future experiments to identify interventions that will enhance neuroprotection.

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“…Only the spliced form of XBP-1 protein is an active transcription factor (50). Moreover, it was demonstrated that GRP78 is implicated in the cellular trafficking, because it is able to translocate to the cell surface (51). Thus, to better understand the effects of glucose deprivation on NEU3, cells were cultured under high glucose concentration (which is the standard condition normally used to culture cells) and normo-and low glucose concentration.…”

Section: Neu3 Sialidase Protein Interactorsmentioning

confidence: 99%

NEU3 Sialidase Protein Interactors in the Plasma Membrane and in the Endosomes

Cirillo

Ghiroldi

Fania

et al. 2016

Journal of Biological Chemistry

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NEU3 sialidase has been shown to be a key player in many physio-and pathological processes, including cell differentiation, cellular response to hypoxic stress, and carcinogenesis. The enzyme, peculiarly localized on the outer leaflet of the plasma membrane, has been shown to be able to remove sialic acid residues from the gangliosides present on adjacent cells, thus creating cell to cell interactions. Nonetheless, herein we report that the enzyme localization is dynamically regulated between the plasma membrane and the endosomes, where a substantial amount of NEU3 is stored with low enzymatic activity. However, under opportune stimuli, NEU3 is shifted from the endosomes to the plasma membrane, where it greatly increases the sialidase activity. Finally, we found that NEU3 possesses also the ability to interact with specific proteins, many of which are different in each cell compartment. They were identified by mass spectrometry, and some selected ones were also confirmed by cross-immunoprecipitation with the enzyme, supporting NEU3 involvement in the cell stress response, protein folding, and intracellular trafficking.

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Characterization and Mechanism of Stress-induced Translocation of 78-Kilodalton Glucose-regulated Protein (GRP78) to the Cell Surface

Cited by 146 publications

References 58 publications

GRP78 Is an Important Host Factor for Japanese Encephalitis Virus Entry and Replication in Mammalian Cells

GRP78 Is an Important Host Factor for Japanese Encephalitis Virus Entry and Replication in Mammalian Cells

GRP78 at the Centre of the Stage in Cancer and Neuroprotection

NEU3 Sialidase Protein Interactors in the Plasma Membrane and in the Endosomes

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