葡萄糖調控蛋白78 (Glucose-Regulated Protein 78, GRP78) 位於內質網中，具有鈣離子結合能力以及保護子的功能，能夠幫助新合成之蛋白質的折疊，使其具有正確的功能和結構。當細胞處於逆境環境下，會誘發細胞中GRP78表現增加。在哺乳動物中，葡萄糖調控蛋白78的基因只有一個，且其啟動子序列上的功能是非常豐富的，透過DNaseⅠfootprint 及gel mobility shift assay已經證實grp78啟動子序列上有許多不同的轉錄蛋白因子與之結合，調節grp78啟動子的活性。
在此論文中我們以9L大白鼠腦腫瘤細胞為材料，根據ER-Stress element重新定義grp78起動子上的調控序列,接著由起動子3’端起做一系列的移除來探討在不同的內質網逆境下，grp78起動子調節元件的功能分析。當細胞在7種不同機制的藥物處理底下，我們觀察到CRE-like (cAMP response element -like) 8個鹼基元件的移除，皆會使起動子的活性明顯的大過於本來未作任何修改的啟動子強度，而△21是所有啟動子活性中最弱的，但是當進一步將其上的ERSE3元件移除後卻會大幅增加其啟動子的活性。因此，根據其他報導我們推測在CRE-like 元件上有屬於CREB-RP(cAMP response element binding protein-related protein)家族的負調控轉錄蛋白與之結合而新被分離出會抑制ER stress gene表現，拮抗YY-1透過core 元件作用而增加grp78轉錄的負調控蛋白轉錄因子YB-1及dbpA則應是更準確的結合在ERSE3元件上。另外，利用鈣離子螯合抑制劑dibromo-1,2-bis(aminophenoxy)ethane N, N, N’, N’-tetracetic acid (BAPTA) ，我們發現除了 thapsigargin (TG) 和 A23187誘導grp78表現是透過鈣離子擾動而會被BAPTA所抑制之外， tunicamycin 及 2-deoxyglucose 這兩種內質網糖化抑制劑和CdCl2這些經由不同機制誘導grp78表現的藥劑同時也會被BAPTA所抑制。據此，我們推測誘導grp78表現的內質網逆境在誘導grp78表現時可能都與鈣離子的訊號傳遞有關。

Glucose regulated protein 78(grp78) is localized in endoplasmic reticulum, it has calcium binding and chaperone function ability. When cells under stress condition grp78 expression will increase. In mammalian cell, grp78 is a single copy gene and its promoter is functionally redundant which by criterion of DNaseⅠfootprint and gel mobility shift assay binding with nuclear factors.
Based on ER-Stress novel promoter regulatory motifs(ERSE) CCAATN9CCACG mediated ER stress response, we identified common cis-regulatory elements on rat grp78 promoter in 9L RBT cells. Using an extensive series of 3’-deletion and CRE-like 8 base pair deletion alone of rat grp78 promoter in a homologous manner. We found that under seven different kinds mechanism drugs treatment, the promoter activity of CRE-like 8 base pair deletion was always significant higher than the intact full length one and Δ21 construct showed the lowest promoter activity that in some treatment even equal or lower than the TATA control construct while addition remove ERSE3 element would promote the promoter activity. Recently, it was reported that overexpression of CREB-Rp (cAMP response element binding protein-related protein) prevents ER stress induced transcription of grp genes mediated by endogenous transactivator. Others reported two new identified Y-box proteins YB-1 and dbpA that repress YY-1 mediated enhanced transcription of grp78 via core element. These lead us to conclude that rat grp78 promoter is strong and many transcription factor binding on its functional redundant element to properly regulate its activity. Some down regulatory transcription factors of CREB-Rp member may bind on CRE-like element. In addition to, negatively control transcription factors YB-1 and dbpA may precisely bind on ERSE3 element that reduce grp78 promoter activity. Moreover, we also showed that stress induces grp78 expression process may all involve in calcium signaling.

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