近期，由中科院水生所淡水生态与生物技术国家重点实验室桂建芳研究员等完成的鱼类低氧反应基因研究成果被《自然·中国》列为研究亮点。
低氧是生物生存的重要环境压力。对于人类和其他陆生脊椎动物而言，低氧压力可以导致很多代谢方面的改变以达到快速适应的目的。然而在水里，氧气溶解度相对较低且没有良好的扩散，所以许多鱼类不得不在行为、生理、生化、分子等方面发展良好的适应机制以应付水环境不断发生的低氧危机。鲫是少数强耐低氧脊椎动物之一，但因其不同个体和不同组织对低氧反应存在差异，因而给系统研究鱼类抗低氧的分子机制带来许多不便。为此，水生所淡水生态与生物技术国家重点实验室桂建芳研究员等以鲫囊胚细胞为材料，通过抑制性差减杂交技术建立了一个适于系统研究鱼类抗低氧分子机制的细胞模型系统。他们在发现血红素加氧酶—1（HO—1）在低氧条件下具有明显上调表达的基础上，克隆并特征分析了该基因。他们发现该血红素加氧酶—1基因广泛表达于健康鲫鱼的后肾、头肾、鳃和肠中，且在后肾组织中有明显的低氧诱导表达增强。GFP融合蛋白亚细胞定位分析表明该基因的蛋白不但定位在细胞质中而且与结构预测相吻合，同时定位在细胞膜上。接下来他们构建了稳定表达HO—1的细胞系CAB/pcDNA3.1—HO—1 和空白对照细胞系CAB/pcDNA3.1，经4天低氧处理（1% O2）后发现CAB/pcDNA3.1—HO—1细胞系较对照细胞系CAB/pcDNA3.1 可以很好的抑制低氧处理所引起的大量细胞脱落死亡。另外，利用CCK—8试剂盒检测两种细胞系在低氧处理和常氧恢复实验中细胞生存力状况时也发现了两种细胞耐受低氧方面的明显不同。因此建议血红素加氧酶—1基因可能对CAB细胞抵抗低氧应激反应方面起到重要的保护作用。
该研究成果的实验工作主要由该实验室的研究生王丹和博士后钟雪萍等完成，研究论文发表在《实验生物学杂志》（Journal of Experimental Biology）。《自然·中国》评论的题目是“Hydrobiology: Out of air, but not out of action”。（生物谷Bioon.com）
生物谷推荐原始出处：
Journal of Experimental Biology，211, 2700-2706 (2008)，Dan Wang，Jian-Fang Gui
Inductive transcription and protective role of fish heme oxygenase-1 under hypoxic stress
Dan Wang, Xue-Ping Zhong, Zhi-Xian Qiao and Jian-Fang Gui*
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan 430072, China
Heme oxygenase-1 is the rate-limiting enzyme in the degradation of heme into biliverdin, carbon monoxide and free divalent iron. In this study, we cloned heme oxygenase isoform 1 (CaHO-1) from a hypoxia-tolerant teleost fish Carassius auratus. The full-length cDNA of CaHO-1 is 1247 bp and encodes a protein of 272 amino acids. RT-PCR and real-time PCR analysis indicated that CaHO-1 was predominantly transcribed in posterior kidney, head kidney, gill and intestine, and induction of gene transcription was observed predominantly in posterior kidney under hypoxic stress. Moreover, the hypoxia-induced transcription was confirmed in goldfish larvae and in in vitro cultured CAB cells. Fluorescence of the HO-1-GFP fusion protein revealed a cytoplasmic and plasma membrane localization, which was consistent with the putative transmembrane structure. Subsequently, we established a stably transfected CAB/pcDNA3.1-HO-1 cell line and a control CAB/pcDNA3.1 cell line, and found that the number of dead cells was obviously reduced in the pcDNA3.1-HO-1-transfected group following 4 days of hypoxic (1% O2) treatment in comparison with numerous detached dead cells in the control pcDNA3.1-transfected cells. Furthermore, a significant cell viability difference between the two kinds of transfected cells during hypoxia–reoxygenation was revealed. Therefore, the data suggest that fish HO-1 might play a significant protective role in cells in response to hypoxic stress.
