PROCESSING OF HCG IN NORMAL AND ABNORMAL PREGNANCIES

我们实验室的初步研究与高糖基化（额外的天线和聚焦残基在n -连接寡糖上）和hCG的切口或切割之间的关系是一致的。其他初步研究表明，高糖基化和缺口hCG分子的结构不稳定和生物活性降低，以及它们如何成为循环中游离β -亚基和尿样中β -核心片段的来源。已发表的论文显示，在滋养细胞疾病、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。我们的假设是，这些升高的水平是由hCG的高糖基化引起的，其途径包括缺口、hCG产生的无效自分泌控制、解离到缺口的游离β亚基和降解到β核心片段。在子痫前期患者中，其他途径可提高hCG水平，降低高糖基化hCG的比例。提出了四组实验来验证这一假设，并研究在正常和异常妊娠中观察到的临床后果。研究拟确认和比较1140组来自正常和异常妊娠的平行血清和尿液样本中hCG、游离β亚基和β核心片段的水平（Aim 1A）；并使用平行血清和尿液样本来研究两种新的免疫测定法的临床应用，这两种免疫测定法专门测量高糖基化hCG和缺口hCG，以及它们在筛查唐氏综合征和先兆子痫中的潜在用途（Aim 1B）。建议进行基础科学研究，从正常妊娠前、中、晚期妊娠尿液样本，以及子痫前期、呕吐性滋养细胞疾病和唐氏综合征妊娠尿液样本（各3份）中纯化hCG，比较切口的程度和部位，以及高糖基化n -低聚糖的类型、数量和位置（Aim 2）。进一步的研究计划通过比较正常和高糖基化的hCG作为切口酶的底物来研究高糖基化与切口的关系（目的3）；并检测21个纯化的正常和异常妊娠分子的生物活性，并确定它们反馈到胎盘并控制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).