內質網（Endoplasmic reticulum）是負責合成膜蛋白及細胞外蛋白的一個關鍵胞器。然而，錯誤摺疊的蛋白質結構可造成不正常的內質網壓力。為了適應內質網壓力（ER stress），內質網會啟動未摺疊蛋白質反應（Unfolded protein response）以阻止蛋白質轉譯並促進未摺疊蛋白質反應基因表現。在過去的研究中，我們證實了內質網壓力誘導內質網膜蛋白Derlin-1的表現。此外，我們發現glutamyl-prolyl-tRNA synthetase (EPRS) 與Derlin-1有相關，而EPRS是aa-tRNA synthetases (aaRS) 的一員，主要負責提供胺基酸接合的tRNA。目前，尚不清楚EPRS或其他aaRS在UPR或內質網壓力中如何發揮作用。在這項研究中，我們進行在內質網壓力下的EPRS實驗。我們發現，在Tunicamycin誘導內質網壓力的狀況下，EPRS和Derlin-1明顯地被誘發。重要的是，EPRS的提升似乎能被聚集至內質網，所以我們使用蛋白質交互作用組數據測試了幾種ER膜蛋白，希望能在ER膜上鑑定出可能與EPRS相互作用的關係。初步資料顯示，Calnexin 99a、ER伴護蛋白將促進EPRS聚集質內質網周邊，綜上所述，這項研究支持在內質網壓力反應中，aaRS扮演重要的角色。

Endoplasmic reticulum (ER) is a key compartment that newly synthesized proteins are translocated in and monitored to be appropriately assembled properly assembled before the secretory process. However, several structurally misfolded proteins with disease-involved-mutation, permanently entrapped in the ER membrane, . To adapt the ER stress, the ER would activate the unfolded protein response (UPR)) to adapt to contemporary stress. to withhold protein translations and facilitate UPR gene expression. That is to say, notwithstanding being studied for a long timeIn a previous study, we identified ER membrane protein Derlin-1, which could be induced by ER stress. Furthermore, we uncovered that glutamyl-prolyl-tRNA synthetase (EPRS) is associated with Derlin-1. EPRS is a member of aa-tRNA synthetases (aaRS) responsible for tRNA charging. , a matterCurrently, it is unclear of how aa-tRNA synthetases relate (EPRS, or other aaRS, might have a role in UPR or ER stress. aaRS) to the UPR mechanism still has been under scrutiny. Thus, aIn this study, we with the Drosophila model is conducted experiments that aim to partially shed a light on the role of glutamyl-prolyl-tRNA synthetase (EPRS) under ER stress. As aWe found that both EPRS downstream of Derlin 1, a component of ER-associated degradation pathway (ERAD), the expression of EPRS and Derlin Derlin-1 is are indicated to be markedly induced under Tunicamycin-triggered ER stress condition, whilst, the later stage of stress slightly inclines its level. Importantly, the increased EPRS seemingly recruited to the ER proximity. We used protein interactome data to test several ER membrane proteins with the hope of identifying a partner(s) on the ER membrane that might potentially interact with EPRS. Consistently, ERPS is strongly localized into the ER membrane. Besides,Preliminary data hinted that Calnexin 99, an ER chaperone, performs might facilitation facilitate to the recruitment of EPRS from the cytosol intoto the ER vicinity. Additionally, the upregulation of Calnexin 99 increases the ERPS expression while knockdown Calnexin 99 decreases its level under ER stress circumstances. Taken together, this study preliminarily provides evidence data about to support a the role of linkage between bifunctional aaRS and in ER stress response.

Almanza A, Carlesso A, Chintha C, et al., (2019). Endoplasmic reticulum stress signalling - from basic mechanisms to clinical applications. FEBS J.;286(2):241286(2
Arensdorf, A. M., Diedrichs, D., & Rutkowski, D. T. (2013). Regulation of the transcriptome by ER stress: non-canonical mechanisms and physiological consequences. Frontiers in genetics, 4, 256.
Arif, A., Jia, J., Moodt, R. A., DiCorleto, P. E., & Fox, P. L. (2011). Phosphorylation of glutamyl-prolyl tRNA synthetase by cyclin-dependent kinase 5 dictates transcript-selective translational control. Proceedings of the National Academy of Sciences of the United States of America, 108(4), 1415–1420.
Arif, A., Yao, P., Terenzi, F., Jia, J., Ray, P. S., & Fox, P. L. (2018). The GAIT translational control system. Wiley interdisciplinary reviews. RNA, 9(2), 10.1002/wrna.1441.
Auf G, Jabouille A, Delugin M, Gu, Gu S, Pineau R, North S, Platonova N, Maitre M, Favereaux A, Vajkoczy P, Seno M, Bikfalvi A, Minchenko D, Minchenko O1, Moenner M. (2013) High epiregulin expression in human U87 glioma cells relies on IRE1es on IRE1(20r M. (20 (20er M. (20 (20M. (20 (20er M. (20oenner M. (20M.
Baird, T. D., Palam, L. R., Fusakio, M. E., Willy, J. A., Davis, C. M., McClintick, J. N., k, J. N., A., Davis, Selective mRNA translation during eIF2 phosphorylation induces expression of IBTKα. Molecular biology of the cell, 25(10), 1686–1697.
Bao, Y., Marini, S., Tamura, T., Kamada, M., Maegawa, S., Hosokawa, H., a,Akutsu, T. (2019). Toward more accurate prediction of caspase cleavage sites: a comprehensive review of current methods, tools and features. Briefings in bioinformatics, 20(5), 1669–1684.
Benbrook, D. M., & Long, A. (2012). Integration of autophagy, proteasomal degradation, unfolded protein response and apoptosis. Experimental oncology, 34 (3), 286-97.
Bergeron, J. J., Brenner, M. B., Thomas, D. Y., & Williams, D. B. (1994). Calnexin: a membrane-bound chaperone of the endoplasmic reticulum. Trends in biochemical sciences, 19(3), 124(3),
Bertolotti, A., Zhang, Y., Hendershot, L. M., Harding, H. P., & Ron, D. (2000). Dynamic interaction of BiP and ER stress transducers in the unfolded-protein response. Nature cell biology, 2(6), 3263263)
Braakman, I., & Hebert, D. N. (2013). Protein folding in the endoplasmic reticulum. Cold Spring Harbor perspectives in biology, 5(5), a013201.
Brandizzi, F., & Barlowe, C. (2013). Organization of the ER-Golgi interface for membrane traffic control. Nature reviews. Molecular cell biology, 14(6), 3826), 38
Brewer, J. W., Hendershot, L. M., Sherr, C. J., & Diehl, J. A. (1999). Mammalian unfolded protein response inhibits cyclin D1 translation and cell-cycle progression. Proceedings of the National Academy of Sciences of the United States of America, 96(15), 8505 8505H
Carvalho, P., Stanley, A. M., & Rapoport, T. A. (2010). Retrotranslocation of a misfolded luminal ER protein by the ubiquitin-ligase Hrd1p. Cell, 143(4), 579 Cell,
Christianson, J. C., & Ye, Y. (2014). Cleaning up in the endoplasmic reticulum: ubiquitin in charge. Nature structural & molecular biology, 21(4), 325–335.
Debard, S., Bader, G., De Craene, J. O., Enkler, L., Bär, S., Laporte, D., e, D., , D., ., , D., , D., rte, D., , D., r, S., Laporte, D., , D., lum: ubitRNA synthetases in yeast and human cells. Methods (San Diego, Calif.), 113, 91–104.
Dunn, K. W., Kamocka, M. M., & McDonald, J. H. (2011). A practical guide to evaluating colocalization in biological microscopy. American journal of physiology. Cell physiology, 300(4), C723, 300(4
Franz, A., Ackermann, L., & Hoppe, T. (2014). Create and preserve: proteostasis in development and aging is governed by Cdc48/p97/VCP. Biochimica et biophysica acta, 1843(1), 205 2055
Guan, B. J., Krokowski, D., Majumder, M., Schmotzer, C. L., Kimball, S. R., Merrick, W. C., … Hatzoglou, M. (2014). Translational control during endoplasmic reticulum stress beyond phosphorylation of the translation initiation factor eIF2ctor eIF2 physiology, 300(4), C723), C723 300(4), C723States o
Guerriero, C. J., & Brodsky, J. L. (2012). The delicate balance between secreted protein folding and endoplasmic reticulum-associated degradation in human physiology. Physiological reviews, 92(2), 537–576.
Gupta S, Deepti A, Deegan S, Lisbona F, Hetz C, Samali A. (2010) HSP72 protects cells from ER stress-induced apoptosis via enhancement of IRE1alpha-XBP1 signaling through a physical interaction. PLoS Biol. 8(7):e1000410.
Guruharsha, K. G., Rual, J. F., Zhai, B., Mintseris, J., Vaidya, P., Vaidya, N., dyArtavanis-Tsakonas, S. (2011). A protein complex network of Drosophila melanogaster. Cell, 147(3), 690–703.
Halawani, D., Gogonea, V., DiDonato, J. A., Pipich, V., Yao, P., China, A., , A., ina, A., na, A., , A., a, A., , A., na, A., (3), 690–70glutamyl-tRNA synthetase by appended noncatalytic WHEP domains. The Journal of biological chemistry, 293(23), 8843l of bi
Hirsch, C., Gauss, R., Horn, S. C., Neuber, O., & Sommer, T. (2009). The ubiquitylation machinery of the endoplasmic reticulum. Nature, 458(7237), 453458(72
Iwasaki N, Sugiyama Y, Miyazaki S, Nakagawa H, Nishimura K, Matsuo S. (2015) An ATF4-Signal-Modulating Machine Other Than GADD34 Acts in ATF4-to-CHOP Signaling to Block CHOP Expression in ER-Stress-Relate. Autophagy. J Cell Biochem. 116(7):1300-9:
Jarosch, E., Geiss-Friedlander, R., Meusser, B., Walter, J., & Sommer, T. (2002). Protein dislocation from the endoplasmic reticulum--pulling out the suspect. Traffic (Copenhagen, Denmark), 3(8), 530ing to
Jeong, E. J., Hwang, G. S., Kim, K. H., Kim, M. J., Kim, S., & Kim, K. S. (2000). Structural analysis of multifunctional peptide motifs in human bifunctional tRNA synthetase: identification of RNA-binding residues and functional implications for tandem repeats. Biochemistry, 39(51), 1577551), 15
Jia, J., Arif, A., Ray, P. S., & Fox, P. L. (2008). WHEP domains direct noncanonical function of glutamyl-Prolyl tRNA synthetase in translational control of gene expression. Molecular cell, 29(6), 679r cell
Johansson-Åkhe, I., Mirabello, C. & Wallner, B. (2019). Predicting protein-peptide interaction sites using distant protein complexes as structural templates. Sci Rep 9, 4267.
Kopp, M. C., Larburu, N., Durairaj, V., Adams, C. J., & Ali, M. (2019). UPR proteins IRE1 and PERK switch BiP from chaperone to ER stress sensor. Nature structural & molecular biology, 26(11), 1053–1062.
Kyriacou, S. V., & Deutscher, M. P. (2008). An important role for the multienzyme aminoacyl-tRNA synthetase complex in mammalian translation and cell growth. Molecular cell, 29(4),
Liang CJ, Chang YC, Chang HC, Wang CK, Hung YC, et al. (2014) Derlin-1 Regulates Mutant VCP-Linked Pathogenesis and Endoplasmic Reticulum Stress-Induced Apoptosis.
Lilley BN, Ploegh HL. Multiprotein complexes that link dislocation, ubiquitination, and extraction of misfolded proteins from the endoplasmic reticulum membrane. Proc Natl Acad Sci U S A. 2005;102(40):142962966429
Marshall, R. S., & Vierstra, R. D. (2019). Dynamic Regulation of the 26S Proteasome: From Synthesis to Degradation. Frontiers in molecular biosciences, 6, 40.
Molinari, M., Eriksson, K. K., Calanca, V., Galli, C., Cresswell, P., Michalak, M., & Helenius, A. (2004). Contrasting functions of calreticulin and calnexin in glycoprotein folding and ER quality control. Molecular cell, 13(1), 125–135.
Moser, B., Hochreiter, B., Herbst, R., & Schmid, J. A. (2017). Fluorescence colocalization microscopy analysis can be improved by combining object-recognition with pixel-intensity-correlation. Biotechnology journal, 12(1), 1600332.
Mukherjee, S., & Zhang, Y. (2011). Protein-protein complex structure predictions by multimeric threading and template recombination. Structure (London, England: 1993), 19(7), 955–966.
Ni, M., & Lee, A. S. (2007). ER chaperones in mammalian development and human diseases. FEBS letters, 581(19), 3641–3651.
Olzmann, J. A., Kopito, R. R., & Christianson, J. C. (2013). The mammalian endoplasmic reticulum-associated degradation system. Cold Spring Harbor perspectives in biology, 5(9), a013185.
Park, S. G., Ewalt, K. L., & Kim, S. (2005). Functional expansion of aminoacyl-tRNA synthetases and their interacting factors: new perspectives on housekeepers. Trends in biochemical sciences, 30(10), 56930(10
Pils, B., Copley, R. R., & Schultz, J. (2005). Variation in structural location and amino acid conservation of functional sites in protein domain families. BMC bioinformatics, 6, 210.
Ray, P. S., & Fox, P. L. (2014). Origin and evolution of glutamyl-prolyl tRNA synthetase WHEP domains reveal evolutionary relationships within Holozoa. PloS one, 9(6), e98493.
Ray, P. S., Arif, A., & Fox, P. L. (2007). Macromolecular complexes as depots for releasable regulatory proteins. Trends in biochemical sciences, 32(4), 158 158
Ribas de Pouplana, L., & Schimmel, P. (2001). Aminoacyl-tRNA synthetases: potential markers of genetic code development. Trends in biochemical sciences, 26(10), 591eins.
Ron, D., & Walter, P. (2007). Signal integration in the endoplasmic reticulum unfolded protein response. Nature reviews. Molecular cell biology, 8(7), 519–529.
Sampath, P., Mazumder, B., Seshadri, V., Gerber, C. A., Chavatte, L., Kinter, M., , M., , M., er, M., tNoncanonical function of glutamyl-prolyl-tRNA synthetase: gene-specific silencing of translation. Cell, 119(2), 19519(2)
Schrag, J. D., Bergeron, J. J., Li, Y., Borisova, S., Hahn, M., Thomas, D. Y., & Cygler, M. (2001). The Structure of calnexin, an ER chaperone involved in quality control of protein folding. Molecular cell, 8(3), 633(3),
Schultz, J., Milpetz, F., Bork, P., & Ponting, C. P. (1998). SMART, a simple modular architecture research tool: identification of signaling domains. Proceedings of the National Academy of Sciences of the United States of America, 95(11), 5857–5864.
Schwanhäusser, B., Busse, D., Li, N., Dittmar, G., Schuchhardt, J., Wolf, J., … Selbach, M. (2011). Global quantification of mammalian gene expression control. Nature, 473(7347), 337–342.
Schwarz, D. S., & Blower, M. D. (2016). The endoplasmic reticulum: structure, function and response to cellular signaling. Cellular and molecular life sciences: CMLS, 73(1), 79–94.
Schwarz, M. A., Lee, D. D., & Bartlett, S. (2018). Aminoacyl tRNA synthetase complex interacting multifunctional protein 1 simultaneously binds Glutamyl-Prolyl-tRNA synthetase and scaffold protein aminoacyl tRNA synthetase complex interacting multifunctional protein 3 of the multi-tRNA synthetase complex. The international journal of biochemistry & cell biology, 99, 197y, 99,
Stauffer, W., Sheng, H. & Lim, H.N. EzColocalization: An ImageJ plugin for visualizing and measuring colocalization in cells and organisms. Sci Rep 8, 15764 (2018)
Tabas, I., & Ron, D. (2011). Integrating the mechanisms of apoptosis induced by endoplasmic reticulum stress. Nature cell biology, 13(3), 184, 18
Walter, F., O'Brien, A., Concannon, C. G., D C. G.,, H., & Prehn, J. (2018). ER stress signaling has an activating transcription factor 6tor 6factor 6 reticulum stress. Nature cell biology, 13(3), 184, 184, 99, 197y, 99, 1977 197
Wek RC. Role of eIF2ss signaling has an activa Control and Adaptation to Cellular Stress. Cold Spring Harb Perspect Biol. 2018;10(7):a032870.
Williams D. B. (2006). Beyond lectins: the calnexin/calreticulin chaperone system of the endoplasmic reticulum. Journal of cell science, 119(Pt 4), 6159(Pt 4
Wu, J.,Subbaiah, K.C.V, Xie.L.H.,Jiang .F.,Mickelsen.D.,Myers.J.R., Tang.W.H.W. (2019). bioRxiv 777490; doi: https://doi.org/10.1101/777490
Wu, X., & Rapoport, T. A. (2018). Mechanistic insights into ER-associated protein degradation. Current opinion in cell biology, 53, 22–28.
Yin J, Gu L, Wang Y, Fan N, Ma Y, Peng Y. (2015) Rapamycin improves palmitate-induced ER stress/NF F ess/NF l biology, 53, 22–28. 4901/777490490, 119(Pt 4), 615, 99, 1977 197sInflamm. 2015:272313.
Young, S. K., Baird, T. D., & Wek, R. C. (2016). Translation Regulation of the Glutamyl-prolyl-tRNA Synthetase Gene EPRS through Bypass of Upstream Open Reading Frames with Noncanonical Initiation Codons. The Journal of biological chemistry, 291(20), 108241(20),
Young, S. K., Baird, T. D., & Wek, R. C. (2016). Translation Regulation of the Glutamyl-prolyl-tRNA Synthetase Gene EPRS through Bypass of Upstream Open Reading Frames with Noncanonical Initiation Codons. The Journal of biological chemistry, 291(20), 108241(20),
Frenkel, Z., Shenkman, M., Kondratyev, M. and Lederkremer, G. Z. (2004). Separate roles and different routing of calnexin and ERp57 in endoplasmic reticulum quality control revealed by interactions with asialoglycoprotein receptor chains. Mol. Biol. Cell 15, 2133–2142.