Amelioration of Aberrant Glycosylation and the Maternal Adaptation to Pregnancy

异常糖基化的改善和母体对妊娠的适应

• 批准号: MR/X000346/1
• 负责人: Steve Charnock-Jones
• 金额: $ 144.33万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FX000346%2F1
• 关键词: Amelioration; Aberrant; Glycosylation; Maternal; Adaptation

Pregnancy is essential for survival but imposes considerable physiological stress on the mother. Maternal metabolism has to adapt to meet the needs of the growing fetus and to prepare for the postnatal demands of lactation. For example, food intake, heart rate, respiration and kidney glomerular filtration all rise. Adverse pregnancy outcomes (such as pre-eclampsia and fetal growth restriction) have life-long consequences for the health of mother and child. Preeclampsia affected ~14,000 women last year in England and such mothers have an eight-fold increased risk of heart disease. We do not know what the mechanism is for this.The placenta grows during pregnancy to transfer nutrients, oxygen and waste products between mother and fetus. The placenta also orchestrates the necessary physiological changes in the mother by secreting a variety of hormones and proteins into the maternal circulation. The majority of proteins released from cells are made inside a cellular compartment - the endoplasmic reticulum (ER). As the newly synthesized proteins are folded in the ER they are further modified by addition of sugar side-chains, forming glycoproteins. The sugars are key to glycoprotein function and their clearance from circulation.Placental dysfunction is implicated in numerous pregnancy disorders (such as pre-eclampsia and growth restriction), and a common feature of these is placental "ER stress". This stress is caused by a wide range of factors including malnutrition, low oxygen levels or infection and it perturbs ER function. We and others have reported that the structure of the sugar side-chains of glycoproteins secreted by cells suffering ER stress are changed or lost, with profound effects on protein function. For example, we have shown that vascular endothelial growth factor (VEGFA, a key factor stimulating blood vessel growth) is inactive if the sugar side-chains are altered by ER stress.Thus, we hypothesise that the placental ER stress seen in complications of pregnancy may result in impaired maternal adaptations to pregnancy. In our pilot studies in which placental ER stress is increased, we see short-term effects on maternal physiology (reduced blood glucose and raised haematocrit) and altered metabolic signalling in the liver. Importantly and very surprisingly, we also found changes in an enzyme that modifies DNA structure (the process of DNA methylation) and which typically leads to long-term changes in gene function. This means that placental ER stress can induce changes in the maternal liver that would persist after pregnancy and potentially into later life. The biochemical and cellular mechanisms that underlie this effect are unknown and the work proposed here directly addresses this.We will use our newly generated genetically modified mouse in which ER function is disrupted specifically in the placenta and nowhere else. We will characterise how ER stress changes the structure of the sugar side-chains on secreted placental proteins. These proteins normally regulate the function of the maternal liver and pancreas and mammary gland growth. We will determine whether the abnormally modified proteins are still active by collecting placental tissue and culturing it in the laboratory. We will use proteins released and specifically study the response of liver and pancreas cells to them. We will also assess mammary gland cell growth and the production of milk proteins and fat accumulation. Some of this work will be performed in mice as we need to study the relationship between changes in placental function and the maternal response.Importantly, we will use a natural bile salt which we have shown reduces placental ER stress and we will determine whether it restores normal maternal physiology. This work will not only improve our understanding of the mechanisms underlying maternal adaptation to pregnancy but will determine whether this drug treatment has therapeutic potential in compromised pregnancies.

怀孕对生存至关重要，但对母亲施加了相当大的生理压力。母亲的新陈代谢必须适应胎儿生长的需要，并为产后哺乳的需要做准备。例如，食物摄入量、心率、呼吸和肾小球滤过率都会上升。不良妊娠结局（如先兆子痫和胎儿生长受限）对母亲和儿童的健康有终身影响。去年，英国约有14000名妇女患先兆子痫，这些母亲患心脏病的风险增加了8倍。我们不知道它的机制是什么。胎盘在怀孕期间生长，在母亲和胎儿之间传递营养、氧气和废物。胎盘还通过向母体循环中分泌各种激素和蛋白质来协调母体必要的生理变化。从细胞中释放出来的大多数蛋白质是在细胞腔室-内质网（ER）内制造的。当新合成的蛋白质在内质网中折叠时，它们通过添加糖侧链进一步修饰，形成糖蛋白。糖是糖蛋白功能及其从循环中清除的关键。胎盘功能障碍与许多妊娠障碍有关（如先兆子痫和生长受限），这些疾病的一个共同特征是胎盘“内质网应激”。这种压力是由多种因素引起的，包括营养不良、低氧水平或感染，它会扰乱内质网功能。我们和其他人已经报道，受到内质网应激的细胞分泌的糖蛋白的糖侧链结构发生改变或丢失，对蛋白质功能产生深远影响。例如，我们已经证明，如果糖侧链被内质网应激改变，血管内皮生长因子（VEGFA，一种刺激血管生长的关键因子）就会失去活性。因此，我们假设妊娠并发症中胎盘内质网应激可能导致母体对妊娠的适应受损。在我们的试点研究中，胎盘内质网应激增加，我们看到对母体生理的短期影响（血糖降低和红细胞压积升高）和肝脏代谢信号的改变。重要且非常令人惊讶的是，我们还发现了一种改变DNA结构（DNA甲基化过程）的酶的变化，这种变化通常会导致基因功能的长期变化。这意味着胎盘内质网应激会引起母亲肝脏的变化，这种变化会在怀孕后持续存在，并可能影响到以后的生活。这种效应背后的生化和细胞机制尚不清楚，这里提出的工作直接解决了这个问题。我们将使用我们新产生的转基因小鼠，其中内质网功能仅在胎盘中被破坏，而在其他地方没有。我们将描述内质网应激如何改变分泌胎盘蛋白的糖侧链结构。这些蛋白质通常调节母体肝脏、胰腺和乳腺的功能。我们将通过收集胎盘组织并在实验室培养来确定异常修饰的蛋白质是否仍然具有活性。我们将使用释放的蛋白质，专门研究肝脏和胰腺细胞对它们的反应。我们还将评估乳腺细胞的生长、乳蛋白的产生和脂肪的积累。由于我们需要研究胎盘功能变化与母体反应之间的关系，因此部分工作将在小鼠身上进行。重要的是，我们将使用一种天然胆汁盐，我们已经证明它可以减少胎盘内质网应激，我们将确定它是否能恢复正常的母体生理机能。这项工作不仅将提高我们对孕妇适应妊娠的机制的理解，而且将确定这种药物治疗是否在受损妊娠中具有治疗潜力。

项目成果

Perturbation of placental protein glycosylation by endoplasmic reticulum stress promotes maladaptation of maternal hepatic glucose metabolism.

• DOI: 10.1016/j.isci.2022.105911
• 发表时间: 2023-01-20
• 期刊: ISCIENCE
• 影响因子: 5.8
• 作者: Yung, Hong Wa;Zhao, Xiaohui;Glover, Luke;Burrin, Charlotte;Pang, Poh-Choo;Jones, Carolyn J. P.;Gill, Carolyn;Duhig, Kate;Olovsson, Matts;Chappell, Lucy C.;Haslam, Stuart M.;Dell, Anne;Burton, Graham J.;Charnock-Jones, D. Stephen
• 通讯作者: Charnock-Jones, D. Stephen