Hypoxia-inducible ERO1-α acts as a member of pre-peptide loading complex and regulates immune responses in the context of MHC class I and class II molecules

人内质网氧化还原素样蛋白（ERO 1-α）是存在于内质网中的一种氧化酶，在缺氧等应激环境下被诱导表达。它通过蛋白质二硫键异构酶（PDI）调节各种蛋白质的氧化还原状态。有趣的是，尽管ERO 1-α在正常组织中的表达相对有限，但各种类型的癌细胞都表达大量ERO 1-α。由于主要组织相容性复合体（MHC）I类分子携带分子内二硫键，我们研究了hERO 1-La是否在癌细胞中的氧化折叠和MHC I类分子的表达中起作用。我们建立了ERO 1-α过表达和敲低的SW 480细胞。结果表明，ERO 1-α过表达的SW 480细胞表面MHCI类分子表达上调，而ERO 1-α敲减的SW 480细胞表面MHCI类分子表达下调。此外，我们还观察到，在hERO 1-La-过度表达中，I类MHC的氧化形式增加。 ...更多信息 表示SW 480。此外，我们观察到hERO 1-La敲低的SW 480对细胞毒性T淋巴细胞（CTL）的应答受损。有趣的是，在正常细胞中，ERO 1-α在抗原呈递细胞如B细胞和树突状细胞中高度表达。由于主要组织相容性复合体（MHC）II类分子也携带分子内二硫键，我们研究了ERO 1-α是否在B细胞系中MHC II类分子的氧化折叠和表达中起作用。由于人B细胞淋巴瘤细胞系BALL-1显示ERO 1-α的高表达，我们使用shRNA产生ERO 1-α敲低的BALL-1细胞。结果表明，与野生型细胞相比，ERO 1-Lα基因敲低的细胞中MHC Ⅱ类分子的表面表达下调。此外，hERO 1-α的敲低导致MHC II类的氧化形式减少，从而减少稳定的肽-MHC II类复合物。提示ERO 1-α可能在机体抗外源抗原的免疫应答中起重要作用。提示ERO 1-α可能通过调节MHC I类和II类分子的表达和质量来调节免疫应答。少

The human endoplasmic reticulum oxidoreductin like(ERO1-α) is an oxidizing enzyme that exists in endoplasmic reticulum and is induced under stress environment such as the hypoxia. It regulates a redox state of various kinds of protein through protein disulfide isomerase(PDI). Interestingly, although the expression of ERO1-α in the normal tissue was comparatively limited, various types of cancer cells expressed the large amount of ERO1-α. As the major histocompatibility complex(MHC) class I molecule carries the intramolecular disulfide bonds, we examined whether the hERO1-La plays a role in the oxidative folding and the expression of MHC class I molecules in cancer cells. We established ERO1-α overexpressed and knockdown SW480 cells. As a result, surface expression of MHC class I molecule was up-regulated in the ERO1-α-overexpressed SW480 and down-regulated in the ERO1-α knockdown SW480. Moreover, we have observed that the oxidized form of MHC class I was increased in the hERO1-La-overe … More xpressed SW480. In addition, we have observed that the hERO1-La knockdown SW480 have an impaired response to cytotoxic T lymphocyte(CTL). Interestingly, ERO1-α is highly expressed in the antigen presenting cells such as B cells and dendritic cells among the normal cells. As the major histocompatibility complex(MHC) class II molecule also carries the intramolecular disulfide bonds, we examined whether the ERO1-α plays a role in the oxidative folding and the expression of MHC class II molecules in B cell line. Because human B cell lymphoma line BALL-1 showed high expression of ERO1-α, we generated BALL-1 cells with ERO1-α knockdown using shRNA. As a result, surface expression of MHC class II molecule was down-regulated in the ERO1-Lα-knockdown cells compared to wild type cells. Moreover, knockdown of hERO1-α resulted in the decrease of oxidized form of MHC class II, thereby decreasing the stable peptide-MHC class II complexes. These data suggested that ERO1-α may play an important role in the immune responses against foreign antigens. These data suggested that the ERO1-α regulates immune response via modulation of MHC class I and class II expression and the quality. Less