In vivo hyaluronan synthesis upon expression of the mammalian hyaluronan synthase gene in Drosophila
In vivo hyaluronan synthesis upon expression of the mammalian hyaluronan synthase gene in Drosophila
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DOI：
10.1074/jbc.m314293200
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发表时间：
2004-04-30
影响因子：
4.8
通讯作者：
Nakato, H
中科院分区：
文献类型：
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作者：
Takeo, S;Fujise, M;Nakato, H
透明质酸(HA)是一种由葡萄糖醛酸和GlcNAc组成的重复双糖的大分子线性聚合物。虽然HA在脊椎动物中广泛分布，但在包括昆虫在内的无脊椎动物中尚未发现。昆虫利用甲壳素作为外骨骼的主要成分，甲壳素是GlcNAc的一种重复的β-1，4连接的均聚物。最近的研究阐明了HA和甲壳素生物合成机制的相似性，并表明HA合成酶(HAS)和甲壳素合成酶是从一个共同的祖先分子进化而来的。虽然Has蛋白的生化特性和体内功能已经得到了广泛的研究，但对HA生物合成的分子基础还不完全清楚。例如，目前还不清楚是否需要适当的链延长和HA的分泌，除了HAS之外还需要其他成分。在这里，我们证明了一种非合成HA的动物，果蝇黑腹果蝇，可以在体内产生HA，当单一的HAS蛋白被引入时。通过Gal4/UAS(上游激活序列)系统在果蝇组织中表达小鼠HAS2基因，导致细胞外大量HA积聚，导致各种形态缺陷。这些形态异常被归因于细胞间通讯的障碍，这是由于HA的积累而不是硫酸乙酰肝素合成的中断。我们还表明，带有HA的成虫翅膀可以保持高水平的水分。这些发现表明，合成甲壳素(但不是HA)的生物能够产生与哺乳动物在结构和功能上相关的HA。昆虫细胞产生HA的能力支持这样一种观点，即在体内合成HA不需要HAS蛋白以外的其他分子。另一种模式是，果蝇细胞使用甲壳素生物合成机制的内源成分来生产和分泌HA。
Hyaluronan (HA) is a large linear polymer of repeating disaccharides of glucuronic acid and GlcNAc. Although HA is widely distributed in vertebrate animals, it has not been found in invertebrates, including insect species. Insects utilize chitin, a repeating beta-1,4-linked homopolymer of GlcNAc, as a major component of their exoskeleton. Recent studies illustrate the similarities in the biosynthetic mechanisms of HA and chitin and suggest that HA synthase ( HAS) and chitin synthase have evolved from a common ancestral molecule. Although the biochemical properties and in vivo functions of HAS proteins have been extensively studied, the molecular basis for HA biosynthesis is not completely understood. For example, it is currently not clear if proper chain elongation and secretion of HA require other components in addition to HAS. Here, we demonstrate that a non-HA-synthesizing animal, the fruit fly Drosophila melanogaster, can produce HA in vivo when a single HAS protein is introduced. Expression of the mouse HAS2 gene in Drosophila tissues by the Gal4/UAS ( upstream activating sequence) system resulted in massive HA accumulation in the extracellular space and caused various morphological defects. These morphological abnormalities were ascribed to disordered cell-cell communications due to accumulation of HA rather than disruption of heparan sulfate synthesis. We also show that adult wings with HA can hold a high level of water. These findings demonstrate that organisms synthesizing chitin ( but not HA) are capable of producing HA that is structurally and functionally relevant to that in mammals. The ability of insect cells to produce HA supports the idea that in vivo HA biosynthesis does not require molecules other than the HAS protein. An alternative model is that Drosophila cells use endogenous components of the chitin biosynthetic machinery to produce and secrete HA.