HIF-l is the earliest documented and most widely studied hypoxia-inducible factor (HIF) and plays a key role in the cell hypoxia signal transduction pathway. Particularly, the HIF-1α protein is sensitive to oxygen and plays a critical role in hypoxia regulation. This study is the first to report on the molecular cloning and characterization of HIF-1α in bighead carp (Aristichthys nobilis; anHIF-1α). The full-length cDNA of anHIF-1α was 2361 bp, and encodes an estimated 674 amino acids with a predicted molecular mass of 76.10 kDa and a theoretical isoelectric point of 7.72. Moreover, the conserved basic Helix-Loop-Helix domain along with two Per-ARNT-Sim domains (A/B), and C-TAD were identified in this protein. Interestingly, the tertiary structure of the anHIF-1α protein was found to be extremely similar to that of mice. Multiple comparison and phylogenetic tree results demonstrated that anHIF-1α was highly conserved. Under normoxic conditions, anHIF-1α mRNA transcripts could be detected in all tissues examined with the highest expression level in the heart. With gradually decreasing oxygen concentrations, anHIF-1α mRNA level was upregulated significantly in the gill, liver, kidney, spleen, intestine, brain, and muscle tissues (P < 0.05). Similarly, anHIF-1α was expressed in all examined bighead carp tissues, and the results suggested that the upregulation of anHIF-1α at the transcriptional level may be an important stress response adaptation to hypoxia in bighead carp. Finally, based on the tertiary structure comparative analyses between anHIF-1α with mouse HIF-1α, we think the physiological function, and protein structure of HIF-1α could be compared between fish and mammal in the future.

HIF-1是最早记载和研究最广泛的缺氧诱导因子（HIF），并且在细胞缺氧信号转导途径中起关键作用。特别地，HIF-1α蛋白对氧敏感，并且在缺氧调节中起关键作用。这项研究是首次上的HIF-1α在鳙鱼分子克隆和表征报告（鳙; anHIF-1α）。anHIF-1α的全长cDNADNA的长度为2361bp，编码估计的674个氨基酸，预测的分子量为76.10kDa，理论等电点为7.72。此外，在该蛋白中鉴定了保守的基本螺旋-螺旋-螺旋结构域以及两个Per-ARNT-Sim结构域（A / B）和C-TAD。有趣的是，发现anHIF-1α蛋白的三级结构与小鼠极为相似。多重比较和系统进化树结果表明anHIF-1α是高度保守的。在常氧条件下，可以在心脏中表达水平最高的所有组织中检测到anHIF-1αmRNA转录本。随着氧气浓度的逐渐降低，anHIF-1α在腮，肝，肾，脾，肠，脑和肌肉组织中，mRNA水平显着上调（P <0.05）。同样，anHIF-1α在所有被检big鱼组织中均表达，结果表明，转录水平上anHIF-1α的上调可能是big鱼低氧适应的重要应激反应。最后，基于anHIF-1α与小鼠HIF-1α的三级结构比较分析，我们认为将来HIF-1α的生理功能和蛋白质结构可以在鱼类和哺乳动物之间进行比较。