DISSECTING THE ROLE OF SIALOGLYCANS IN EMBRYONIC DEVELOPMENT

剖析唾液酸聚糖在胚胎发育中的作用

• 批准号: 513175479
• 负责人: Dr. Markus Abeln
• 金额: --
• 依托单位: Institut für Klinische Biochemie
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/513175479?language=en
• 关键词: DISSECTING; ROLE; SIALOGLYCANS; EMBRYONIC; DEVELOPMENT

The mammalian sialome, particularly cell surface expressed sialoglycans, has essential functions in signaling ‘self’ and ‘foreign’. By targeting CMP-sialic acid synthase (CMAS), the enzyme catalyzing metabolic activation of sialic acid (Sia), we generated an asialo system, exhibiting embryonic (E) lethality at day 8.5, clearly demonstrating that sialoglycans are indispensable during pregnancy. Studies on the cause of fetal demise identified an untamed activation of the alternative branch of the maternal complement system with massive deposition of the complement component 3b (C3b) on the semi-allogeneic trophoblast cells with concurrent inflammation at the feto-maternal interface. However, we could exclude formation of the membrane attack complex and demonstrated that signaling via the anaphylotoxins C3a and C5a has no impact on phenotype development. In contrast, we saw a massive invasion of maternal platelets and in pilot studies were able to largely prevent complement activation and inflammation by inhibition of maternal platelets. Combined with literature data attributing platelets a role in placental inflammation, our preliminary data induced the question studies on the molecular events that stimulate platelet activation and deleterious consequences in the asialo-background. To uncover Sia functions apart from complement regulation the double knockout Cmas-/-;C3-/- was generated. A prominent characteristic of Cmas-/-;C3-/- are severe neuronal hemorrhages, which are highly reminiscent to the phenotypes of mice with genetic alterations that impair formation of hematopoietic stem cells (HSC). We thus pursue the goal to understand the role of sialoglycans in hematopoiesis and the differentiation of HSCs. The massive thromboinflammation seen at the fetal-maternal interface of Cmas-/- implants demonstrates that sialylation is essential at the boundary layer between fluid phase and solid tissue. While endothelial expressed sialoglycans have been studied with regard to different aspects and are known to participate in the maintenance of hemostasis and leukocyte recruitment, a model that would allow to study of endothelial functions in the absence of Sia is missing. In the course of the current project we will generate Cdh5-Cre/ERT2; Cmaslox/lox mice that enable the tamoxifen induced and endothelial specific loss of sialylation also in adult animals and will use this model to address Sia functions in endothelia.

哺乳动物唾液酸体，特别是细胞表面表达的唾液酸聚糖，在信号传导“自身”和“外来”中具有重要功能。通过靶向CMP-唾液酸合酶（CMAS）（催化唾液酸（Sia）代谢活化的酶），我们产生了一种脱唾液酸系统，在第8.5天显示胚胎（E）致死性，清楚地表明唾液酸聚糖在妊娠期间是不可或缺的。对胎儿死亡原因的研究确定了母体补体系统的替代分支的未驯服激活，补体成分3b（C3 b）大量沉积在半同种异体滋养层细胞上，同时在胎儿-母体界面处发生炎症。然而，我们可以排除膜攻击复合物的形成，并证明通过葡萄球菌毒素C3 a和C5 a的信号传导对表型发育没有影响。相反，我们看到母体血小板的大量侵入，并且在初步研究中能够通过抑制母体血小板在很大程度上防止补体激活和炎症。结合文献数据归因于血小板在胎盘炎症中的作用，我们的初步数据引发了对刺激血小板活化的分子事件和无唾液酸背景下的有害后果的问题研究。为了揭示除了补体调节之外的Sia功能，产生了双敲除Cmas-/-;C3-/-。Cmas-/-;C3-/-的一个突出特征是严重的神经元损伤，这与具有损害造血干细胞（HSC）形成的遗传改变的小鼠的表型高度相关。因此，我们追求的目标是了解唾液酸聚糖在造血和HSC分化中的作用。在Cmas-/-植入物的胎儿-母体界面处观察到的大量血栓炎症表明唾液酸化在流体相和固体组织之间的边界层处是必不可少的。虽然内皮表达的唾液酸聚糖已经在不同方面进行了研究，并且已知其参与止血和白细胞募集的维持，但是缺少允许在不存在Sia的情况下研究内皮功能的模型。在当前项目的过程中，我们将产生Cdh 5-Cre/ERT 2; Cmaslox/lox小鼠，其也能够在成年动物中实现他莫昔芬诱导的和内皮特异性的唾液酸化丧失，并将使用该模型来解决内皮中的Sia功能。