缢蛏HIF-1和PHD2基因鉴定及其在低氧胁迫下的表达

Identification and expression analysis of HIF-1 and PHD2 genes in razor clam (Sinonovacula constricta) under hypoxia stress

  • 摘要:
    目的 了解HIF信号通路对于动物在低氧环境下的代谢和能量平衡调节等发挥的作用。
    方法 利用PCR技术克隆了缢蛏 HIF信号通路中的4个关键基因HIF-1αHIF-1βPHD2APHD2B,对其编码蛋白的理化性质和结构域进行预测,并对其系统发育关系进行分析。
    结果 HIF-1包含典型的HLH、PAS、PAC、C-TAD结构域,HIF-1α特有ODDD和N-TAD结构域,ScPHD2含有zf-MYND和P4Hc结构域;不同于其他无脊椎动物,贝类包括缢蛏PHD2具有两个拷贝。利用实时荧光定量PCR(RT-qPCR)技术,进一步对HIF-1和PHD2在不同发育阶段、成体不同组织和低氧(0.5 mg/L和2.0 mg/L)及干露(21 ℃干露和4 ℃干露)胁迫下的表达水平进行了分析。结果显示,缢蛏HIF-1和PHD2在卵子时期便开始表达,ScHIF-1α在检测的6个组织中的表达水平高于其他基因,且在鳃中表达最高,肝胰腺次之,ScPHD2AScPHD2B在6个组织的表达量均很低。低氧胁迫下,ScHIF-1α、ScPHD2表达受到显著上调,但0.5 mg/L组较2 mg/L组上调幅度更大,而ScHIF-1β表达量变化不显著。干露胁迫下,ScHIF-1β表达量变化不显著,ScHIF-1α、ScPHD2表达显著上调,且4 ℃干露组较21 ℃干露上调幅度更大。
    结论 ScHIF-1和ScPHD2分别具备典型的HIF和PHD家族特征,且在低氧下被诱导上调表达,表明其可能参与了缢蛏低氧胁迫后应答过程。研究结果为深入开展缢蛏低氧信号通路和低氧适应机制研究提供了参考价值。

     

    Abstract: The HIF (hypoxia-inducible factor) signaling pathway is an oxygen-sensing signaling pathway in animals, and plays important roles in metabolism and energy homeostasis in hypoxia environments. In this study, four key genes of HIF signaling pathway, HIF-1α, HIF-1β, PHD2A and PHD2B, were cloned using PCR from Sinonovacula constricta, and the physicochemical properties and domains of their encoded proteins were predicted, and analyzed their phylogenetic relationships. The results showed that HIF-1 contained typical HLH, PAS, PAC, and C-TAD domains, HIF-1α specific ODDD and N-TAD domains, and ScPHD2 contained zf-MYND and P4Hc domains; unlike other invertebrates, shellfish including razor clam PHD2 had two copies. Using real-time fluorescence quantitative PCR (RT-qPCR), the expression levels of HIF-1 and PHD2 were further analyzed at different developmental stages, in different tissues of adults and under hypoxia (0.5 mg/L and 2.0 mg/L) and air exposion (21 ℃ air exposion and 4 ℃ air exposion) stresses. The results showed that razor clam HIF-1 and PHD2 were expressed from the egg stage, ScHIF-1α was expressed at higher levels than other genes in the six tissues examined, and the highest expression was in gill, followed by hepatopancreas, while ScPHD2A and ScPHD2B were expressed at very low levels in all six tissues. Under hypoxia stress, ScHIF-1α and ScPHD2 expressions were significantly up-regulated, but the 0.5 mg/L group was more up-regulated than the 2 mg/L group, while ScHIF-1β expressions were not significantly changed. Under air exposion stress, ScHIF-1β expression did not change significantly, while ScHIF-1α and ScPHD2 expression were significantly up-regulated, and the up-regulation was greater in the 4 ℃ air exposion group than in the 21 ℃ air exposion group. It was shown that ScHIF-1 and ScPHD2 possessed typical HIF and PHD family characteristics, respectively, and their expression was induced to be up-regulated under hypoxia, suggesting that they may be involved in the response process of razor clam after low oxygen stress. The results of the study provide a reference value for further research on the hypoxia signaling pathway and hypoxia adaptation mechanism of razor clam.

     

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