低氧胁迫对瘤背石磺糖酵解途径的影响

Effects of hypoxia stress on glycolysis pathway of Onchidium reevesii

  • 摘要: 【目的】 探究低氧胁迫对瘤背石磺(Onchidium reevesii)糖酵解途径的影响,明确其能量代谢途径转换机制,以了解潮间带物种对缺氧环境的适应策略。【方法】 克隆瘤背石磺葡萄糖转运蛋白1基因(OrGLUT-1)并进行生物信息学分析。采用实时荧光定量PCR检测OrGLUT-1基因在瘤背石磺不同组织中的表达,以及低氧胁迫0、1、3、6、12 h时神经节和肝胰腺组织中糖酵解相关基因OrGLUT-1基因、己糖激酶基因(HK)和丙酮酸激酶基因(PK)的表达。检测不同低氧胁迫时间的瘤背石磺神经节组织中糖酵解酶HKPK及乳酸脱氢酶(LDH)活性。【结果】 OrGLUT-1基因cDNA序列全长2386 bp,开放阅读框(ORF)长度为1656 bp,编码551个氨基酸残基。OrGLUT-1蛋白分子式为C2706H4282N702O786S24,分子量为59.995 kD,理论等电点(pI)为5.79,OrGLUT-1蛋白二级结构以α-螺旋和无规则卷曲为主。基于GLUT-1氨基酸序列相似性构建的系统发育树显示,瘤背石磺与加州海兔(Aplysia californica)的亲缘关系较密切。OrGLUT-1在不同组织中均有表达,但具有明显的组织特异性,在肝胰腺、神经节及性腺组织中的相对表达量较高。低氧胁迫不同时间后,神经节和肝胰腺组织中OrGLUT-1、HK和PK基因的相对表达量均较低氧胁迫前上调,其中神经节组织的响应比肝胰腺组织更迅速。低氧胁迫不同时间后,神经节组织中HK、PK和LDH活性均较低氧胁迫前上升,表明瘤背石磺在低氧胁迫下会通过糖酵解途径来获取能量。【结论】 低氧胁迫下瘤背石磺糖酵解相关基因表达量明显上调,糖酵解酶活性在低氧胁迫下明显升高,表明糖酵解通量大幅增强。瘤背石磺适应潮间带缺氧环境的策略可能是将能量代谢途径从有氧代谢转换为无氧代谢,以启动糖酵解途径获取能量。

     

    Abstract: 【Objective】 To explore the effects of hypoxia stress on the glycolysis pathway of Onchidium reevesii, clarify the conversion mechanism of its energy metabolism pathway, which could study the adaptation strategy of intertidal species to hypoxia environments. 【Method】 The glucose transporter 1 gene(OrGLUT-1) of Onchidium reevesii was cloned and subjected to bioinformatics analysis. Real-time fluorescence quantitative PCR was used to detect the expression of OrGLUT-1 gene in different tissues of Onchidium reevesii, as well as the expressions of glycolysis-related genes(OrGLUT-1), hexokinase gene(HK) and pyruvate kinase gene(PK) in ganglion and hepatopancreas tissues under hypoxia stress at 0,1,3,6,12 h. The activities of glycolytic enzymes(HK, PK) and lactate dehydrogenase(LDH) in the ganglion tissue of Onchidium reevesii under different hypoxia stress times were determined. 【Result】 The full-length cDNA sequence of OrGLUT-1 gene was 2386 bp, with an open reading frame(ORF) of 1656 bp, encoding 551 amino acid residues. The molecular formula of the OrGLUT-1 protein was C2706H4282N702O786S24, with a molecular weight of 59.995 kD and a theoretical isoelectric point(pI) of 5.79. The secondary structure of the OrGLUT-1 protein was mainly composed of α-helices and random coils. The phylogenetic tree constructed based on the amino acid sequence similarity of GLUT-1 showed that Onchidium reevesii had a close genetic relationship with California sea hare(Aplysia californica). OrGLUT-1 was expressed in different tissues but with obvious tissue specificity, and its relative expression levels were higher in the hepatopancreas, ganglion and gonad tissues. After different periods of hypoxia stress, the relative expression levels of OrGLUT-1, HK and PK genes in the ganglion and hepatopancreas tissues were all up-regulated compared with those before hypoxia stress, and the response of the ganglion tissue was more rapid than that of the hepatopancreas tissue. After different hypoxia stress times, the activities of HK, PK and LDH in the ganglion tissue all increased compared with those before hypoxia stress, indicating that Onchidium reevesii could obtain energy through the glycolytic pathway under hypoxia stress. 【Conclusion】 Under hypoxia stress, the glycolysis-related genes of Onchidium reevesii are greatly upregulated, and the activities of glycolytic enzymes are greatly increased, indicating a substantial enhancement of glycolytic flux. The strategy of Onchidium reevesii to adapt to the hypoxic environment in the intertidal zone may be to switch the energy metabolism pathway from aerobic metabolism to anaerobic metabolism, thereby activating the glycolysis pathway to obtain energy.

     

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