Milton Sarah L, Nayak Gauri, Lutz Peter L, Prentice Howard M
Department of Biological Sciences SC 281, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA.
J Biomed Sci. 2006 Jul;13(4):509-14. doi: 10.1007/s11373-006-9084-8. Epub 2006 Apr 25.
Neuroglobin is a heme protein expressed in the vertebrate brain in mammals, fishes, and birds. The physiological role of neuroglobin is not completely understood but possibilities include serving as an intracellular oxygen-carrier or oxygen-sensor, as a terminal oxidase to regenerate NAD(+) under anaerobic conditions, or involvement in NO or ROS metabolism. As the vertebrate nervous system is particularly sensitive to hypoxia, an intracellular protein that helps sustain cellular respiration would aid hypoxic survival. However, the regulation of Neuroglobin (Ngb) under conditions of varying oxygen is controversial. This study examines the regulation of Ngb in an anoxia-tolerant vertebrate under conditions of hypoxia and anoxia. The freshwater turtle Trachemys scripta can withstand complete anoxia for days, and adaptations that permit neuronal survival have been extensively examined. Turtle neuroglobin specific primers were employed in RT-PCR for determining the regulation of neuroglobin mRNA expression in turtles placed in normoxia, hypoxia (4 h), anoxia (1 and 4 h), and anoxia-reoxygenation. Whole brain expression of neuroglobin is strongly upregulated by hypoxia and post-anoxic-reoxygenation in T. scripta, with a lesser degree of upregulation at 1 and 4 h anoxia. Our data implicate neuroglobin in mediating brain anoxic survival.
神经球蛋白是一种在哺乳动物、鱼类和鸟类等脊椎动物大脑中表达的血红素蛋白。神经球蛋白的生理作用尚未完全明确，但可能的作用包括作为细胞内氧载体或氧传感器，作为在无氧条件下使NAD(+)再生的末端氧化酶，或参与一氧化氮或活性氧代谢。由于脊椎动物的神经系统对缺氧特别敏感，一种有助于维持细胞呼吸的细胞内蛋白将有助于缺氧状态下的生存。然而，在不同氧含量条件下神经球蛋白（Ngb）的调节存在争议。本研究考察了耐缺氧脊椎动物在缺氧和无氧条件下神经球蛋白的调节情况。淡水龟滑龟能够耐受数天的完全缺氧，并且已经对其允许神经元存活的适应性进行了广泛研究。在逆转录聚合酶链反应（RT-PCR）中使用龟神经球蛋白特异性引物，以确定处于常氧、缺氧（4小时）、无氧（1和4小时）以及无氧复氧状态下的龟神经球蛋白mRNA表达的调节情况。在滑龟中，神经球蛋白的全脑表达在缺氧和无氧复氧后被强烈上调，在无氧1小时和4小时时上调程度较小。我们的数据表明神经球蛋白在介导大脑的无氧生存中发挥作用。
