Spitsin S V, Koprowski H, Michaels F H
Biotechnology Foundation Laboratories, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Mol Med. 1996 Mar;2(2):226-35.
Nitric oxide has a wide variety of homeostatic and pathological effects. Control of the production of nitric oxide by the inducible form of the enzyme resides in the 5' promoter region of the gene. Although control of the murine isoform has been investigated, little is known about the functional aspects of the human analog.
A 3.9-kb 5' nontranslated region of the human gene was cloned, sequenced, and several reporter constructs prepared. The promoter-reporter constructs were transfected into human or murine monocytoid cells and reporter expression quantified following cytokine activation of the cells. The production of nitric oxide was also monitored.
Although a murine promoter-reporter functioned efficiently in both human and mouse cells, the human constructs functioned only in human cells. The activity of the mouse construct increased progressively with the addition of activating cytokines, but the human promoter-reporter did not. Although interleukin 1 beta drove expression of the human inducible nitric oxide synthase reporter, actual expression of nitric oxide required both interleukin 1 beta and interferon-gamma.
The data indicate that despite the significant homology between the human and mouse inducible nitric oxide synthase promoter sequence, control of the two genes is quite different. In addition to being more efficient in promoter activity, the murine promoter responds increasingly to cytokines that are not effective for the human analog. It is also apparent that human inducible nitric oxide synthase is controlled at both the level of transcription and post-translationally.
一氧化氮具有多种稳态和病理效应。诱导型一氧化氮合酶产生的一氧化氮受该基因5'启动子区域的调控。虽然已经对小鼠同工型的调控进行了研究，但对人类同源物的功能方面了解甚少。
克隆了人类基因3.9kb的5'非翻译区，进行了测序，并制备了几种报告基因构建体。将启动子-报告基因构建体转染到人或小鼠单核细胞样细胞中，并在细胞因子激活细胞后对报告基因表达进行定量。还监测了一氧化氮的产生。
虽然小鼠启动子-报告基因在人和小鼠细胞中均有效发挥作用，但人类构建体仅在人类细胞中发挥作用。小鼠构建体的活性随着激活细胞因子的添加而逐渐增加，但人类启动子-报告基因则不然。虽然白细胞介素1β驱动人类诱导型一氧化氮合酶报告基因的表达，但一氧化氮的实际表达需要白细胞介素1β和干扰素-γ两者。
数据表明，尽管人类和小鼠诱导型一氧化氮合酶启动子序列之间存在显著同源性，但这两个基因的调控却大不相同。除了在启动子活性方面更有效外，小鼠启动子对人类同源物无效的细胞因子的反应也越来越强。同样明显的是，人类诱导型一氧化氮合酶在转录水平和翻译后水平均受到调控。
