Funcioal analysis of mouse EDEM, which eaocelerales gyocprotein ERAD

小鼠 EDEM 的功能分析，其中 eaocelerales 球蛋白 ERAD

• 批准号: 13680780
• 负责人: HOSOKAWA Nobuko
• 金额: $ 1.66万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680780/
• 关键词: ERAD(ER associated degadation); ER quality control; Glyooprotein; ER marnosidase I; ER(endoplasmicreticulun); 糖蛋白質; 小胞体マンノンダーゼ

Newly synthesized proteins in the ER(endoplasmic reticulum) are sorted out to the secretory pathway after they fold or assemble correctly, while misfoled or misassembled proteins are retained in the ER. This mechanism is known as ER quality control. Misfolded proteins in the ER are retrotranslocated out of the ER,followed by degradation by cytosolic proteasome, which is called as ERAD(ER associated degradation). We have cloned a mouse gene, and named it as EDEM(ER degradation enhancing α-mannosidase like-protein), which accelerated the ERAD of misfolded glycoproteins.In the present study, we have clarified the followings:1. We are usingα1-antitrypsin variant null (Hong Kong) (NHK)as a model substrate for ERAD. It is known that the mannose trimming by the ER Mannosidase I(ER Man I) become the signal for glycoprotein ERAD. We have clarified that overexpression of ER Man I into human embryonic kidney 293 cells enhanced the degration of NHK. We also found that the effect of ER Man I and EDEM are additive. We conclude that the misfolded glycoproteins are recognized both by ER Man I and by EDEM before they are degraded2. NHK has one cysteine residue near its Cterminus, thus it is possible that they make disulfide-bonded dimer. We have clarified that NHK make homodimer within the cells, and that coexpression of EDEM inhibited the dimer formation. Disulfide-bonded dimer is expectedly retrotraslocated out of the ER less effciently. On the contrary, EDEM did not affect the secretion or degradation of wild type α1-antitrypsin, which folds correctly in the ER. Taken together, we expect that EDEM keep the misfolded glycoprotein degradation competent

内质网中新合成的蛋白质在正确折叠或组装后被整理到分泌途径，而折叠错误或组装错误的蛋白质则保留在内质网中。这种机制被称为ER质量控制。内质网中错误折叠的蛋白质被反转录转出内质网，随后被细胞质蛋白酶体降解，这被称为ERAD（内质网相关降解）。我们克隆了一个小鼠基因，并将其命名为EDEM（ER降解增强α-甘露糖苷酶样蛋白），该基因加速了错误折叠糖蛋白的ERAD。在本研究中，我们澄清了以下几点：1。我们使用α1-抗胰蛋白酶变体null (Hong Kong) （NHK）作为ERAD的模型底物。已知内质网甘露糖苷酶I（ER Man I）对甘露糖的修饰成为糖蛋白ERAD的信号。我们已经阐明，ER Man I在人胚胎肾293细胞中的过表达增强了NHK的降解。我们还发现ermani和EDEM的作用是加性的。我们得出结论，错误折叠的糖蛋白在被降解之前被ER Man I和EDEM识别。NHK在其Cterminus附近有一个半胱氨酸残基，因此它们有可能形成二硫键二聚体。我们已经阐明了NHK在细胞内产生同型二聚体，而EDEM的共表达抑制了二聚体的形成。二硫键二聚体在内质网外的反位效率较低。相反，EDEM不影响野生型α - 1抗胰蛋白酶的分泌和降解，α - 1抗胰蛋白酶在内质网中正确折叠。综上所述，我们期望EDEM保持错误折叠的糖蛋白降解能力

项目成果

Oda Y, Hosokawa N, Wada I, Nagata K: "EDEM as an acceptor of terminally misfolded glycoproteins released from catnexin"Science. 299. 1394-1397 (2003)

Oda Y、Hosokawa N、Wada I、Nagata K：“EDEM 作为从 catnexin 释放的末端错误折叠糖蛋白的受体”科学。

Sato K, Yomogida K, Yorihuzi T, Nishimune Y, Hosokawa N Nagata K: "Type XXVI collagen, a new member of the collagen family, is specifically expressed in the testis and ovary"J. Biol Chem.. 277. 37678-37684 (2002)

Sato K、Yomogida K、Yorihuzi T、Nishimune Y、Hosokawa N Nagata K：“XXVI 型胶原蛋白是胶原蛋白家族的新成员，在睾丸和卵巢中特异性表达”J.

Nakatsukasa, K.et al.: "Mml1p, an α-mannosidase-like protein in yeast Saccharonyces cerevisiae, is required for endoplasmic reticulum-associated degradation of glycoproteins"The Journal of Biological Chemistry. 276. 8635-8638 (2001)

Nakatsukasa, K. 等人：“Mml1p 是酿酒酵母中的一种 α-甘露糖苷酶样蛋白，是内质网相关糖蛋白降解所必需的”生物化学杂志 276. 8635-8638 (2001)。

Yoshida H, Matsui T, Hosokawa N, Kaufinan R.J, Nagata K, Mori K: "A time-dependent phase shift in the mammalian unfolded protein response"Dev. Cell. (in press). (2003)

Yoshida H、Matsui T、Hosokawa N、Kaufinan R.J、Nagata K、Mori K：“哺乳动物未折叠蛋白反应中的时间依赖性相移”Dev。

Hosokawa N, Wada I, Hasegawa K, Yorihuzi T, Tremblay L.O, Herscovics A, Nagata K: "A novel ER α-manaosidase-like protein accelerates ER-associated degradation"EMBO Reports. 2. 415-422 (2001)

Hosokawa N、Wada I、Hasekawa K、Yorihuzi T、Tremblay L.O、Herscovics A、Nagata K：“一种新型 ER α-manaosidase 样蛋白加速 ER 相关降解”EMBO 报告。