Kikuchi H, Hikage M, Miyashita H, Fukumoto M
Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 980-8575, Sendai, Japan.
Gene. 2000 Aug 22;254(1-2):237-43. doi: 10.1016/s0378-1119(00)00258-4.
The NADPH oxidases are a group of plasma membrane-associated enzymes found in a variety of cells. They catalyze the production of superoxide (O(-)(2)) by a one-electron reduction of oxygen, using NADPH as the electron donor. To characterize the expression of this enzyme, two homologues of the NADPH oxidase catalytic subunit, gp91(phox), were cloned from the cDNAs of a human colon cancer cell line, Caco2, and human fetal kidney, using information relating to an expressed sequence tag (EST) from a DNA database. Amino acid identity was 58% (gp91-2) and 56% (gp91-3), respectively, against the catalytic subunit (gp91-1/gp91(phox)) of the NADPH oxidase found in peripheral blood leukocytes. Using the reverse transcription-polymerase chain reaction (RT-PCR) method, the messenger RNA of gp91-2 was detected mainly in the colon (and also in kidney and prostate) among human adult tissues, in the thymus among human fetal tissues, and in the cancer cell lines (HepG2 and Caco2). An expression of gp91-3 was detected in the fetal kidney, and in the cancer cell line (HepG2), but not at all in adult tissues (by the RT-PCR method). In situ hybridization revealed that gp91-2 is located in the absorptive epithelial cells of the adult colon. Neither gp91-2 nor gp91-3 was expressed in peripheral blood leukocytes.
NADPH氧化酶是一类存在于多种细胞中的与质膜相关的酶。它们以NADPH作为电子供体，通过单电子还原氧气来催化超氧化物（O(-)(2)）的生成。为了表征这种酶的表达情况，利用来自DNA数据库的一个表达序列标签（EST）的相关信息，从人结肠癌细胞系Caco2和人胎儿肾脏的cDNA中克隆了NADPH氧化酶催化亚基gp91(phox)的两个同源物。与在外周血白细胞中发现的NADPH氧化酶的催化亚基（gp91-1/gp91(phox)）相比，氨基酸同一性分别为58%（gp91-2）和56%（gp91-3）。使用逆转录-聚合酶链反应（RT-PCR）方法，在成人组织中，gp91-2的信使RNA主要在结肠（以及肾脏和前列腺）中被检测到，在胎儿组织中主要在胸腺中被检测到，在癌细胞系（HepG2和Caco2）中也被检测到。gp91-3的表达在胎儿肾脏和癌细胞系（HepG2）中被检测到，但在成人组织中完全未被检测到（通过RT-PCR方法）。原位杂交显示gp91-2位于成人结肠的吸收性上皮细胞中。在外周血白细胞中未检测到gp91-2和gp91-3的表达。
