The function and regulation of the novel pregnancy-specific hexokinase HKDC1

 描述（由申请人提供）：妊娠期糖尿病（GDM），即妊娠期发病的糖尿病，可导致母亲和后代的急性和慢性不良结局。该建议的总体目标是了解新的己糖激酶基因HKDC1在GDM发病机制中的作用。在最近的一项高血压和不良妊娠结局（HAPO）队列的遗传研究中，PI和共同作者报告了一个与妊娠期母体血糖性状相关的新基因座。该区域的主要候选基因，含己糖激酶结构域1（HKDC1），尚未得到表征。这项建议将测试的核心假设，HKDC 1是一种新的第五脊椎动物己糖激酶，控制葡萄糖稳态在怀孕期间。验证这一假设很重要，因为它将揭示导致全球最常见的妊娠并发症之一的新机制。这些结果也将对理解脊椎动物代谢产生广泛的影响，因为己糖激酶是糖酵解的第一步，而该领域的教条是只有四种脊椎动物己糖激酶亚型。对第五己糖激酶的功能和调节进行表征将挑战这一教条，并将开辟几个新的研究领域。中心假设将在三个互补层面上进行检验。首先，HKDC 1蛋白的己糖激酶活性将被广泛表征。来自PI的初步数据已经证明HKDC 1具有己糖激酶活性。这一目标将通过系统地表征HKDC 1及其亚基的动力学，将HKDC 1置于其他己糖激酶的背景下。其次，将评估HKDC 1在妊娠期间葡萄糖稳态中的体内作用。组织表达模式表明，HKDC1调节葡萄糖稳态在怀孕期间，特别是通过其在胰腺癌细胞和肝脏的作用。通过整体和组织特异性消融小鼠模型，将评估妊娠期间的葡萄糖稳态。第三，HKDC1在人类妊娠期间调节葡萄糖的作用将通过检验GDM相关遗传变异改变HKDC1在妊娠环境中的调节这一假设来研究。该假设将使用新型高通量报告基因检测进行测试，以（i）发现调节HKDC 1表达的主要和次要激素和葡萄糖反应元件，以及（ii）鉴定改变原始GWAS人群中调节元件功能的遗传变异。这个提议的结果将是HKDC1编码一种新的己糖激酶，其表达的改变会影响妊娠期间的葡萄糖稳态。这一结果将为妊娠期间的葡萄糖代谢提供新的见解。

 DESCRIPTION (provided by applicant): Gestational diabetes (GDM), diabetes with onset during pregnancy, can result in acute and chronic adverse outcomes for mother and offspring. The overall objective of this proposal is to understand the role of the novel hexokinase gene HKDC1 in the pathogenesis of GDM. In a recent genetic study of the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) cohort, the PIs and co-authors reported a novel loci associated with maternal glycemic traits specifically during pregnancy. The lead candidate gene in the region, hexokinase- domain containing 1 (HKDC1), has not been characterized. This proposal will test the central hypothesis that HKDC1 is a novel fifth vertebrate hexokinase that controls glucose homeostasis during pregnancy. Testing that hypothesis is important because it will reveal new mechanisms contributing to one of the most common complications of pregnancy worldwide. The results will also have broad-reaching impacts on understanding vertebrate metabolism because hexokinase is the first step in glycolysis, and the dogma in the field is that there are only four vertebrate hexokinase isoforms. Characterizing the function and regulation of the fifth hexokinase will challenge that dogma and will open up several new areas of study. The central hypothesis will be tested at three complementary levels. First, the hexokinase activity of the HKDC1 protein will be extensively characterized. Preliminary data from the PIs already demonstrate that HKDC1 has hexokinase activity. This aim will place HKDC1 in the context of the other hexokinases by systematically characterizing the kinetics of HKDC1 and its subunits. Second, the in vivo role of HKDC1 in glucose homeostasis during pregnancy will be assessed. Tissue expression patterns suggest that HKDC1 regulates glucose homeostasis during pregnancy specifically through its role in pancreatic ß cells and liver. Through global and tissue-specific ablation mouse models, glucose homeostasis during pregnancy will be assessed. Third, the role of HKDC1 in regulating glucose during human pregnancy will be investigated by testing the hypothesis that GDM-associated genetic variants alter regulation of HKDC1 in the pregnant environment. That hypothesis will be tested using novel high-throughput reporter assays (i) to discover the primary and secondary hormone and glucose response elements that regulate HKDC1 expression and (ii) to identify genetic variants that alter regulatory element function in the original GWAS population. The outcome of this proposal will be that HKDC1 encodes a novel hexokinase whose altered expression impacts glucose homeostasis during pregnancy. This outcome will provide new insight into glucose metabolism during pregnancy.