Analysis of prostaglandin E2 synthases

本研究的目的是研究两种前列腺素E2脱氢酶（PGES）的生物化学特性，并阐明其生理和病理功能。这种酶与p23相同，p23与分子伴侣Hsp 9 O相关。cPGES在功能上与环氧合酶（考克斯）-1偶联以促进PGE 2的立即产生。Hsp 9 O结合的cPGES是一种活性形式，并且在用A23187活化细胞后立即促进该复合物的形成。Hsp 9 O抑制剂，如格尔德霉素，以及糖皮质激素防止Hsp 9 O/cPGES复合物的形成，从而减弱PGE 2的生物合成反应。在细胞活化后，cPGES从胞质溶胶易位到内质网，在那里它与考克斯-1共定位。cPGES经历磷酸化，尽管它的生物学意义是 ...更多信息 难以捉摸最后，至少有四种cPGES的选择性剪接变体，每种变体都表现出不同的组织分布，并且对底物PGH 2表现出不同的动力学参数（Km和Vmax）。微粒体PGES（mPGES）是一种核周18-kDa蛋白，其在各种细胞和组织中被促炎刺激强烈诱导。这种酶属于微粒体谷胱甘肽-S转移酶家族。mPGES在功能上与考克斯-2偶联，明显优先于考克斯-1，以促进延迟的PGE 2产生和引发的立即PGE 2产生。共转染考克斯-2和mPGES到HEK 293细胞中导致培养物中的侵袭性生长和形态学改变。此外，共转染子在软琼脂中生长以形成大的集落，并且在裸鼠中具有致瘤性。结肠癌细胞系（HCA-7）的生长依赖于考克斯-2，也表达mPGES，其中两种酶共定位于核周区。免疫组织化学染色显示考克斯-2和mPGES在结肠肿瘤、类风湿性关节炎、缺血性心脏、C型肝炎和脑内皮细胞中表达。少

The aims of this study are to perform biochemical characterization of two prostaglandin E2 synthases (PGESs) and to clarify their physilogical and pathological functions.Cytosolic PGES (cPGES) is a cytosolic 23-kDa protein that is expressed ubiuitously and constitutively in a wide variety of cells and tissues. This enzyme is identical to p23, which is associated with the molecular chaperone Hsp9O. cPGES is functionally coupled with cyclooxygenase (COX)-1 to promote immediate PGE2 production. The Hsp9O-bound cPGES is an active form, and the formation of this complex is facilitated immediately after cell activation with A23187. Hsp9O inhibitors, such as geldanamycin, as well as glucocorticoid prevents the formation of the Hsp9O/cPGES complex, thereby attenuating the PGE2biosynthetic response. After cell activation, cPGES translocates from the cytosol to the endoplasmic reticulum, where it is colocalized with COX-1. cPGES undergoes phosphorylation, although its biological significance rem … More ains elusive. Finally, there are at least four alternative spliced variants of cPGES, each of which exhibited distinct tissue distribution and showed different kinetic parameters (Km and Vmax) for the substrate PGH2.Microsomal PGES (mPGES) is a perinuclear 18-kDa protein that is strongly induced in various cells and tissues following proinflamamtory stimuli. This enzyme belongs to the class microsomal glutathione-Stransferase family. mPGES is functionally coupled with COX-2 in marked preference to COX-1 to promote delayed PGE2 production and primed immediate PGE2 production. Cotransfection of COX-2 and mPGES into HEK293 cells results in aggressive growth and morphological change in culture. Furthermore, the cotransfectants grow in soft agar to form large colonies and are tumorigenic in nude mice. A colon carcinoma cell line (HCA-7), the growth of which depends on COX-2, also expresses mPGES, where both enzymes are colocalized in the perinuclear reagion. Immunohistochemical staining of human tissues reveal that both COX-2 and mPGES are expressed in colon tumors, rheumatoid arthritis, ischemic hearts, C-type hepatitis, and brain endothelial cells. Less