PROCESSING OF HCG IN NORMAL AND ABNORMAL PREGNANCIES

我们实验室的初步研究与高糖基化（N-连接寡糖上的额外触角和岩藻糖残基）和hCG切口或切割之间的关系一致。其他初步研究表明高糖基化和有缺口的hCG分子的结构不稳定性和生物活性降低，以及它们如何可能是循环中游离β亚基和尿样中β核心片段的来源。 已发表的论文显示，滋养层疾病、妊娠剧吐或唐氏综合征妊娠患者的血清或尿液样本中hCG水平升高，游离β亚基和β核心片段水平比例升高。 我们假设这些升高的水平是由hCG的高糖基化引起的，通过涉及切口、hCG产生的无效自分泌控制、解离为切口游离β亚基和降解为β核心片段的途径。 其他途径提高hCG水平，降低子痫前期患者高糖基化hCG的比例。提出了四组实验来检验这一假设，并调查在正常和异常妊娠的观察的临床后果。 拟对1140组正常和异常妊娠的平行血清和尿液样本中的hCG、游离β-亚单位和β-核心片段水平进行确认和比较（目的1A）;并使用平行的血清和尿液样品来研究两种新的免疫测定法的临床应用，所述免疫测定法特异性地测量高糖基化hCG和缺口hCG，及其在唐氏综合征和先兆子痫筛查中的潜在用途（Aim 1B）。 建议进行基础科学研究，以从正常妊娠早期、中期和晚期尿液样本以及先兆子痫、妊娠剧吐滋养层疾病和唐氏综合征妊娠尿液样本（各3份）中纯化hCG，并比较切口的程度和部位以及高糖基化N-连接寡糖的类型、数量和位置（目的2）。计划进行进一步的研究，通过比较正常和高糖基化hCG作为切口酶的底物来研究高糖基化-切口关系（目的3）;并检查21种纯化的正常和异常妊娠分子的生物活性，并确定其反馈至胎盘和控制hCG合成的能力（目的4）。

Preliminary studies in our laboratory are consistent with a relationship between hyperglycosylation (additional antennae and fucose residues on N-linked oligosaccharides) and nicking or cleavage of hCG. Other preliminary studies indicate the structural instability and diminished biological activity of hyperglycosylated and of nicked hCG molecules, and how they may be the source of free beta-subunit in the circulation and beta-core fragment in urine samples. Papers have been published showing raised hCG levels, and raised proportions of free beta-subunit and beta-core fragment levels in serum or urine samples from patients with trophoblast disease, hyperemesis gravidarum, or Down syndrome pregnancies. It is our hypothesis these raised levels arise from the hyperglycosylation of hCG, through pathways involving nicking, ineffectual autocrine control of hCG production, and dissociation to nicked free beta-subunit, and degradation to beta-core fragment. Other pathways raise levels of hCG and lower the proportions of hyperglycosylated hCG in patients with preeclampsia. Four sets of experiments are proposed to test this hypothesis and investigate the clinical ramification of the observations in normal and abnormal pregnancies. Studies are proposed to confirm and compare the levels of hCG, free beta-subunit and beta-core fragment in 1140 sets of parallel serum and urine samples from normal and abnormal pregnancies (Aim 1A); and to use the parallel serum and urine samples to investigate the clinical use of two new immunoassays that specifically measure hyperglycosylated hCG and nicked hCG, and their potential uses in screening for Down syndrome and preeclampsia (Aim 1B). Basic science studies are proposed to purify hCG from normal first, second and third trimester pregnancy urine samples, and preeclampsia, hyperemesis trophoblast disease and Down syndrome pregnancy urine samples (3 each) and compare the extents and sites of nicking, and the type, amounts and locations of hyperglycosylated N-linked oligosaccharides (Aim 2). Further studies are planned to investigate the hyperglycosylation- nicking relationship by comparing normal and hyperglycosylated hCG as substrates for nicking enzymes (Aim 3); and to examine the biological activities of the 21 purified normal and abnormal pregnancy molecules, and to determine their ability abilities to feedback through to the placenta and control hCG synthesis (Aim 4).