The Syk kinase SmTK4 of Schistosoma mansoni is involved in the regulation of spermatogenesis and oogenesis.
The Syk kinase SmTK4 of Schistosoma mansoni is involved in the regulation of spermatogenesis and oogenesis.
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DOI：
10.1371/journal.ppat.1000769
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发表时间：
2010-02-12
期刊：
影响因子：
6.7
通讯作者：
Grevelding CG
中科院分区：
文献类型：
--
作者：
Beckmann S;Buro C;Dissous C;Hirzmann J;Grevelding CG
来自曼氏血吸虫的信号转导蛋白SmTK 4属于Syk激酶家族。在脊椎动物中，已知Syk激酶在造血系统细胞的信号传导途径中发挥专门作用。虽然Syk激酶在一些无脊椎动物中被发现，但它们在这组动物中的作用尚未阐明。由于SmTK 4是第一个Syk激酶从寄生蠕虫，显示主要在成年蠕虫的睾丸和卵巢中表达，我们研究了它的功能。为了解开信号级联SmTK 4参与，酵母双/三杂交文库筛选进行与串联SH 2结构域，或与接头区，包括酪氨酸激酶结构域的SmTK 4。除了Src激酶SmTK 3，我们确定了一个新的Src激酶（SmTK 6）的上游SmTK 4和MAPK激活蛋白，以及mapmodulin作用下游。他们的身份和共定位的研究指出，SmTK 4的作用，在信号级联调节细胞的增殖和/或分化的性腺中的雌激素受体。为了证实这一决定性的作用，我们进行了生物化学和分子的方法来敲低SmTK 4结合一种新的协议，共聚焦激光扫描显微镜的形态分析。使用Syk激酶特异性抑制剂Piceatannol或通过体外RNAi处理成体染色体，在睾丸和卵巢中检测到相应的表型。在非洲爪蟾卵母细胞系统中，最终证实了Piceatannol抑制SmTK 4的催化激酶结构域的活性。我们的研究结果表明SmTK 4在配子发生中的关键作用，这是真核生物中Syk激酶的一种新功能。血吸虫属的寄生血吸虫引起血吸虫病，血吸虫病是世界范围内人类和动物最重要的传染病之一。除了它们的医学重要性，染色体还具有独特的生物学特征。其中之一是雌性的性成熟，这需要与雄性持续的配对接触。配对诱导雌性的有丝分裂活性和分化过程，导致性腺发育。这是卵子产生的先决条件，这与疾病的病理后果密切相关，因为卵子被困在不同的宿主器官中，诱导炎症过程。虽然这些相关性是众所周知的，在女性性腺分化过程的分子基础知之甚少。在鉴定控制雌性生殖发育的信号转导蛋白的背景下，我们鉴定了S. mansoni，第一个Syk家族激酶的寄生虫。本研究通过生物化学和分子生物学方法，结合体外培养和显微镜技术，证实了SmTK 4信号蛋白在精子发生和卵子发生中的关键作用。mansoni这是真核生物Syk激酶促进SmTK 4作为阻断传播和疾病进展的候选靶标的新属性。
The signal transduction protein SmTK4 from Schistosoma mansoni belongs to the family of Syk kinases. In vertebrates, Syk kinases are known to play specialized roles in signaling pathways in cells of the hematopoietic system. Although Syk kinases were identified in some invertebrates, their role in this group of animals has not yet been elucidated. Since SmTK4 is the first Syk kinase from a parasitic helminth, shown to be predominantly expressed in the testes and ovary of adult worms, we investigated its function. To unravel signaling cascades in which SmTK4 is involved, yeast two-/three-hybrid library screenings were performed with either the tandem SH2-domain, or with the linker region including the tyrosine kinase domain of SmTK4. Besides the Src kinase SmTK3 we identified a new Src kinase (SmTK6) acting upstream of SmTK4 and a MAPK-activating protein, as well as mapmodulin acting downstream. Their identities and colocalization studies pointed to a role of SmTK4 in a signaling cascade regulating the proliferation and/or differentiation of cells in the gonads of schistosomes. To confirm this decisive role we performed biochemical and molecular approaches to knock down SmTK4 combined with a novel protocol for confocal laser scanning microscopy for morphological analyses. Using the Syk kinase-specific inhibitor Piceatannol or by RNAi treatment of adult schistosomes in vitro, corresponding phenotypes were detected in the testes and ovary. In the Xenopus oocyte system it was finally confirmed that Piceatannol suppressed the activity of the catalytic kinase domain of SmTK4. Our findings demonstrate a pivotal role of SmTK4 in gametogenesis, a new function for Syk kinases in eukaryotes. Parasitic blood flukes of the genus Schistosoma cause schistosomiasis, one of the most important infectious diseases for humans and animals worldwide. Besides their medical importance, schistosomes possess unique biological features. Among these is the sexual maturation of the female, which requires a constant pairing contact with the male. Pairing induces mitogenic activity and differentiation processes in the female that lead to gonad development. This is a prerequisite for egg production, which is closely connected with the pathological consequences of the disease since the eggs are trapped in different host organs, inducing inflammatory processes. Although these correlations are long known, the molecular basis of differentiation processes in female gonads are poorly understood. In the context of identification of signal transduction proteins controlling female reproductive development we identified SmTK4 of S. mansoni, the first Syk-family kinase of a parasite. By using biochemical and molecular approaches in combination with in vitro culture and a novel microscopical technique, we demonstrate in this study the pivotal role of the signaling protein SmTK4 in spermatogenesis and oogenesis of S. mansoni. This is a new attribute for Syk kinases of eukaryotes promoting SmTK4 as a candidate target for blocking transmission and disease progression.