MOUSE MODELS FOR STUDIES OF THE RETINOBLASTOMA GENE

这项研究的长期目标是了解分子 组织类型特异性肿瘤易感性的机制 肿瘤抑制基因的失活突变。模型系统 正在研究的是视网膜母细胞瘤，一种儿童眼部肿瘤。涉及到的基因， Rb-1是1987年用定位克隆的方法分离出来的。这个 视网膜母细胞瘤基因产物广泛表达，有许多 有趣的特性表明，它可能在 细胞分裂周期。肿瘤的限谱观察 另一方面，人类视网膜母细胞瘤家系的类型是 与目前假设的Rb基因的功能相矛盾。至 进一步解决这个问题，我们已经使用同源重组来 灭活小鼠胚胎干细胞中的一个Rb等位基因 建立了一种携带Rb基因胚系突变的小鼠品系。 杂合子小鼠不会患上视网膜母细胞瘤，但容易患上 脑瘤的透视率大于95%。以下是目标 建议研究Rb基因在细胞和细胞中的功能 分子水平：a)杂合小鼠中的神经元肿瘤将是 以免疫染色为特征的各种标志物的表达模式 将与人类视网膜母细胞瘤进行比较。这些研究将 为两种特定组织类型的肿瘤易感性提供依据 不同的物种，人类和老鼠。B)RB的功能后果 将对神经细胞的失活进行研究。是否放松管制 神经细胞增殖先于细胞死亡将被研究。基因 在RB失活后其表达被改变的将是 特色化的。这些研究将揭示分子事件可能 与神经系统中的Rb功能有关。C)功能界别 Rb在造血干细胞中失活的后果将是 通过将干细胞移植到野生型受体中进行研究 老鼠。这些方法将区分细胞-自治的或非自治的 Rb基因在造血谱系中的自主功能。D) 纯合子Rb缺陷者的发育和致瘤潜力 胚胎干细胞将在野生型小鼠背景下进行跟踪。 这些研究将提供所有细胞中Rb功能的全局视角 类型。E)野生型Rb等位基因在组织中的特异性失活 利用酵母FLP重组酶培育杂合子小鼠 系统。这些实验将导致一个明确的系统，其中组织- 可以更详细地剖析该基因的特定功能。

The long-term goal of this investigation is to understand the molecular mechanisms underlying tissue-type specific tumor predisposition by the inactivational mutation of the tumor suppressor genes. The model system for study is retinoblastoma, a childhood ocular tumor. The gene involved, RB-1, was isolated by a positional cloning approach in 1987. The retinoblastoma gene product is ubiquitously expressed and has many interesting properties that indicate it may play a regulatory role in the cell division cycle. The observation of the limited spectrum of tumor types in the human retinoblastoma pedigree, on the other hand, is paradoxical to the current hypothetical function of the RB gene. To further address this issue, we have used homologous recombination to inactivate one RB allele in mouse embryonic stem cells and have established a mouse strain carrying a germ-line mutation of the RB gene. Heterozygous mice do not develop retinoblastoma, but are predisposed to brain tumor with greater than 95% penetrance. The following aims are proposed to study the function of the RB gene at the cellular and molecular levels: A) The neuronal tumors in the heterozygous mice will be characterized by immunostaining, the expression pattern of various markers will be compared to that of the human retinoblastoma. These studies will provide the basis of tumor predisposition of specific tissue type in two different species, humans and mice. B) The functional consequences of RB inactivations in the neuronal cells will be studied. Whether deregulated neuronal cell proliferation precedes cell death will be studied. Genes whose expression has been altered following RB inactivation will be characterized. These studies will reveal the molecular events that might be related to the RB function in the nervous system. C) The functional consequences of RB inactivations in the hematopoietic stem cells will be studied by transplantation of the stem cells into the wild-type recipient mice. These approaches will differentiate the cell-autonomous or non- autonomous function of the RB gene in the hematopoietic lineage. D) The developmental and tumorigenic potential of the homozygous RB-deficient embryonic stem cells will be followed in a wild-type mouse background. These studies will provide a global view of the RB function in all cell types. E) A tissue-specific inactivation of the wild-type RB allele in the heterozygous mice will be developed using the yeast FLP recombinase system. These experiments will lead to a defined system where the tissue- specific function of the gene can be dissected at greater detail.