Identification, expression and bioactivity of hexokinase in amphioxus: insights into evolution of vertebrate hexokinase genes.
Identification, expression and bioactivity of hexokinase in amphioxus: insights into evolution of vertebrate hexokinase genes.
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DOI：
10.1016/j.gene.2013.10.068
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发表时间：
2014-02
期刊：
影响因子：
3.5
通讯作者：
Mengyang Li;Zhan Gao;Yu Wang;Hui Wang;Shicui Zhang
中科院分区：
文献类型：
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作者：
Mengyang Li;Zhan Gao;Yu Wang;Hui Wang;Shicui Zhang
己糖激酶家族包括己糖激酶I、II、III和IV，它们催化葡萄糖的磷酸化生成葡萄糖6-磷酸。己糖激酶IV，也被称为葡糖激酶，只有其他类型的己糖激酶酶的一半大小，后者包含两个己糖激酶域。尽管己糖激酶的研究取得了巨大的进展，但葡糖激酶与其他己糖激酶之间的进化关系仍然不确定，导致脊椎动物中己糖激酶出现的分子过程也仍然存在争议。在这里，我们清楚地证明了在文昌鱼Branchiostoma Japan onicum(Bjhk)中存在一个类似己糖激酶的基因，该基因具有组织特异性表达模式，在肝盲肠、睾丸和卵巢中表达最丰富。系统发育和同源性分析都表明BjHK是脊椎动物己糖激酶IV的原型，即葡萄糖激动酶。我们还首次发现重组BjHK具有类似于脊椎动物己糖激酶I、II、III和IV的功能酶活性。此外，在肝盲肠中还检测到天然的葡糖激酶活性。最后，禁食显著降低肝脏盲肠中的葡萄糖激活酶活性，而摄食则显著提高其活性。综上所述，这些结果表明Bjhk代表了葡萄糖激动酶的原型，脊椎动物的己糖激酶基因家族是由基因复制而来的，肝盲囊在文昌鱼的葡萄糖平衡中起着控制作用，支持肝盲囊是与肝脏同源的组织的观点。
Hexokinase family includes hexokinases I, II, III and IV, that catalyze the phosphorylation of glucose to produce glucose 6-phosphate. Hexokinase IV, also known as glucokinase, is only half size of the other types of hexokinases that contain two hexokinase domains. Despite the enormous progress in the study of hexokinases, the evolutionary relationship between glucokinase and other hexokinases is still uncertain, and the molecular processes leading to the emergence of hexokinases in vertebrates remain controversial. Here we clearly demonstrated the presence of a single hexokinase-like gene in the amphioxusBranchiostoma japonicum,Bjhk, which shows a tissue-specific expression pattern, with the most abundant expression in the hepatic caecum, testis and ovary. The phylogenetic and synteny analyses both reveal that BjHK is the archetype of vertebrate hexokinases IV, i.e. glucokinases. We also found for the first time that recombinant BjHK showed functional enzyme activity resembling vertebrate hexokinases I, II, III and IV. In addition, a native glucokinase activity was detected in the hepatic caecum. Finally, glucokinase activity in the hepatic caecum was markedly reduced by fasting, whereas it was considerably increased by feeding. Altogether, these suggest thatBjhkrepresents the archetype of glucokinases, from which vertebrate hexokinase gene family was evolved by gene duplication, and that the hepatic caecum plays a role in the control of glucose homeostasis in amphioxus, in favor of the notion that the hepatic caecum is a tissue homologous to liver.