Sialic acid acetylesterase (SIAE) removes acetyl moieties from the carbon 9 and 4 hydroxyl groups of sialic acid and recently a debate has been opened on its association to autoimmunity. Trying to get new insights on this intriguing enzyme we have studied siae in zebrafish (Danio rerio). In this teleost siae encodes for a polypeptide with a high degree of sequence identity to human and mouse counterparts. Zebrafish Siae behavior upon transient expression in COS7 cells is comparable to human enzyme concerning pH optimum of enzyme activity, subcellular localization and glycosylation. In addition, and as already observed in case of human SIAE, the glycosylated form of the enzyme from zebrafish is released into the culture media. During embryogenesis, in situ hybridization experiments demonstrate that siae transcript is always detectable during development, with a more specific expression in the central nervous system, in pronephric ducts and liver in the more advanced stages of the embryo development. In adult fish an increasing amount of siae mRNA is detectable in heart, eye, muscle, liver, brain, kidney and ovary. These results provide novel information about Siae and point out zebrafish as animal model to better understand the biological role(s) of this rather puzzling enzyme in vertebrates, regarding immune system function and the development of central nervous system.

中文翻译：

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斑马鱼中唾液酸乙酰酯酶（siae）的基因组和生化特性

唾液酸乙酰酯酶（SIAE）可以从唾液酸的9和4个羟基碳原子上除去乙酰基，最近人们开始讨论其与自身免疫性的关系。为了获得关于这种有趣酶的新见解，我们研究了斑马鱼中的siae（Danio rerio）。在这个硬骨猿编码与人和小鼠对应物具有高度序列同一性的多肽。在酶活性，亚细胞定位和糖基化的最佳pH值方面，在COS7细胞中瞬时表达后，斑马鱼Siae行为可与人类酶媲美。另外，正如在人SIAE中已经观察到的那样，来自斑马鱼的酶的糖基化形式被释放到培养基中。在胚胎发生过程中，原位杂交实验表明，siae转录本在发育过程中始终可检测到，在胚胎发育的更高级阶段在中枢神经系统，肾前管和肝脏中具有更特异性的表达。成年鱼中的唾液含量增加在心脏，眼睛，肌肉，肝脏，大脑，肾脏和卵巢中均可检测到mRNA。这些结果提供了有关Siae的新颖信息，并指出了斑马鱼作为动物模型，以更好地了解这种相当令人费解的酶在脊椎动物中的生物学作用，涉及免疫系统功能和中枢神经系统的发育。