Studies of Trypanosoma cruzi trans-sialidase using transfection method

克氏锥虫的反式唾液酸酶催化一个(2-3)连接的唾液酸从宿主衍生的糖结合物转移到寄生虫表面的粘蛋白样受体分子上，反之亦然。一些证据表明，寄生虫和宿主细胞表面的反式唾液酸酶和唾液酸化分子对于细胞入侵和寄生虫逃离宿主防御系统是重要的。在感染性鞭毛虫期(T-TS)表达的酶通过糖基磷脂酰肌醇(GPI)锚点定位在寄生虫表面，在体外很容易进入培养上清，在体内很容易进入动物的血液。另一方面，反式唾液酸酶在非感染性表鞭毛体阶段也可以检测到，但它不会释放到介质中，也不会被T-TS的羧基末端重复序列抗体识别。实际上，有两种类型的反式唾液酸酶基因家族，它们位于不同的染色体上，受不同的调控。…此外，我们还对这两种不同类型的反式唾液酸酶的功能、分子表达机制和定位进行了研究，获得了这两个家族的多个基因，并在比较的基础上制备了一些衍生物、杂交型反式唾液酸酶分子。这两种类型的N-末端序列没有相似之处，都是高度疏水的，可以作为分泌蛋白和膜蛋白的信号肽。T-TS的C-末端疏水区被GPI-锚结构取代，似乎对分泌并不重要。在表鞭毛体(E-TS)中表达的反式唾液酸酶(E-TS)的N-末端和C-末端区域的结构特征与T-TS相似。利用杂交分子和分子标签表位对两个TS的不同定位甚至结构相似性的分子研究正在进行中。塔夫茨大学与Pereira博士的合作研究表明，T-TS C-末端重复序列可以诱导人内皮细胞和外周血单核细胞分泌IL-6。较少

Trypanosoma cruzi trans-sialidase catalyzes the transfer of a(2-3) linked sialic acid from host derived glycoconjugates to the parasite surface mucin-like acceptor molecules and vice versa. Several lines of evidence suggest that trans-sialidase and sialylated molecules on the parasite and host cell surface are important for cell invasion and parasite escape from host defense systems. The enzyme expressed in infective trtpomastigote stage (T-TS) is located on the parasite surface through a glycosyl phosphatididylinositol (GPI) anchor, and readily shed into culture supernatant in vitro and into the bloodstream of animals in, vivo. On the other hands, trans-sialidase is also detectable in noninfective epimastigote stage, however this is not released into the medium nor recognized by antibodies against the carboxyl terminal repeats of T-TS. Actually, there are two types of trans-sialidase gene families, which are localized at different chromosomes and controlled under different regulation. … More We have studied functions, molecular mechanisms of expression and localization of these two different types of trans-sialidases.We have obtained several genes of these two families and prepared some derivatives, hybrid trans-sialidase molecules based on comparison. Both N-terminal sequences of these two types, in which there are no similarities, are highly hydrophobic and functioned as signal peptides of secretary and membrane proteins. C-terminal hydrophobic region of T-TS which is replaced by GPI-anchor structure seems to be not important for secretion. The structural feature of N- and C-terminal regions of trans-sialidase expressed in epimastigote (E-TS) are similar to those of T-TS. Molecular studies of different localization of two TS even structural similarity are ongoing using hybrid molecules and molecular tag epitope.The collaboration research with Dr. Pereira, Tafts University could have shown that T-TS C-terminal repeats induce IL-6 secretion from human endothelial cells and peripheral blood mononuclear cells. Less