SEQUENCES CONTROLLING H19 GENE IMPRINTING

哺乳动物中的大多数基因在母体和母体中的表达是一样的 父系遗传的等位基因。然而，有些基因是由父母决定的 印记，并且只在单亲的等位基因中表达。 印记基因的一个后果是单个突变或缺失， 在表达的等位基因中，会导致基因产物的缺失。 这些类型的突变很可能与遗传性疾病有关，如 作为Beckwith-Wiedemann综合征、Prader-Willi综合征和Angelman 综合症。相反，IGF2和IGF2两个基因印迹的松弛 H19与肾母细胞瘤中的基因激活有关，可能是 这是参与癌症发展的一种新的遗传机制的一部分。这个 本提案中描述的研究的目标是了解如何 印记基因的亲本身份被指定。这些研究将采用 H19基因，它是由母系衍生的等位基因在 老鼠和人类。最近的研究表明，H19的非活性等位基因 高度甲基化表明甲基化可能参与了 印记的调解。此外，对H19转基因的分析， 它概括了内源基因座的印记，表明 顺式作用序列可以用来测试印迹的授予 转基因小鼠。本方案中设计的实验将：(I) 确定等位基因特异性甲基化是否指定并保持 首先评估胚芽中等位基因特异性甲基化的亲本认同感 细胞和早期胚胎，然后诱变CpG二核苷酸， 保持差异甲基化并检测转基因中改变的DNA 小鼠；(2)使用转基因小鼠鉴定顺式作用序列 使H19基因被印记，然后确定是否 最小的识别序列将印记另一个哺乳动物基因；以及(3) 评估菌株特异性反式作用修饰物在 印迹新衍生的转基因小鼠品系。这些实验 最终将允许识别反式作用因子， 确定印记。对印记过程的理解 正常操作将使您更好地了解印记是如何 在诸如肾母细胞瘤等癌症中发生改变。

Most genes in mammals are expressed equally from the maternally and paternally inherited alleles. However, some genes are parentally imprinted, and are expressed exclusively from a single parent's allele. One consequence of imprinted genes is that a single mutation or deletion, in the expressed allele, will result in the absence of a gene product. These types of mutations are most likely involved in genetic diseases such as Beckwith-Wiedemann Syndrome, Prader-Willi Syndrome and Angelman Syndrome. In contrast, relaxation of the imprinting of two genes, IGF2 and H19, has been associated with gene activation in Wilms' tumor and may be part of a new genetic mechanism involved in the development of cancer. The objective of the studies described in this proposal is to learn how parental identity of imprinted genes is assigned. The studies will employ the H19 gene, which is expressed from the maternally derived allele in mice and humans. The recent demonstration that the inactive allele of H19 is highly methylated suggests that methylation may be involved in the mediation of imprinting. Furthermore, the analysis of H19 transgenes, which recapitulate the imprinting of the endogenous locus, indicates that cis-acting sequences can be tested for the conferral of imprinting using transgenic mice. The experiments designed in this proposal will: (i) determine if allele-specific methylation designates and perpetuates parental identity by first assessing allele-specific methylation in germ cells and the early embryo, and then mutagenizing CpG dinculeotides that remain differentially methylated and testing the altered DNA in transgenic mice; (2) use transgenic mice to identify the cis-acting sequences that cause the H19 gene to be imprinted and subsequently determine if the minimal identified sequences will imprint another mammalian gene; and (3) assess the role of strain-specific trans-acting modifiers in the imprinting of the newly derived transgenic mouse lines. These experiments will eventually allow the identification of trans-acting factors that determine imprinting. An understanding of how the imprinting process normally operates will allow greater understanding of how imprinting is altered in cancers such as Wilms' tumor.