MOUSE MODELS FOR STUDIES OF THE RETINOBLASTOMA GENE

这项研究的长期目标是了解 组织类型特异性肿瘤易感性的潜在机制 肿瘤抑制基因的失活突变。模型系统 视网膜母细胞瘤是一种儿童眼部肿瘤。相关基因， RB-1是在1987年通过定位克隆方法分离的。的 视网膜母细胞瘤基因产物广泛表达， 有趣的特性表明它可能在细胞凋亡中起调节作用。 细胞分裂周期肿瘤有限光谱的观察 另一方面，在人类视网膜母细胞瘤谱系中， 这与目前假设的RB基因功能相悖。到 为了进一步解决这个问题，我们使用同源重组来 在小鼠胚胎干细胞中发现了一个RB等位基因， 建立了一种携带RB基因种系突变的小鼠品系。 杂合子小鼠不会发生视网膜母细胞瘤，但易患视网膜母细胞瘤。 95%以上转移率的脑瘤以下目标是 建议研究RB基因在细胞和组织中的功能， 分子水平：A）杂合小鼠中的神经元肿瘤将是 通过免疫染色表征，各种标记物的表达模式 将与人类视网膜母细胞瘤的情况进行比较。这些研究将 提供两种特定组织类型肿瘤易感性的依据 不同的物种，人类和老鼠。B）RB的功能后果 将研究神经元细胞中的失活。是否解除管制 将研究神经元细胞增殖先于细胞死亡。基因 其表达在RB失活后改变， 表征了这些研究将揭示分子事件， 与神经系统中的RB功能有关。C.功能 造血干细胞中RB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 小鼠这些方法将区分细胞自主或非自主。 RB基因在造血谱系中的自主功能。D）The 纯合子RB缺陷型的发育和致瘤潜力 将在野生型小鼠背景中跟踪胚胎干细胞。 这些研究将提供RB功能在所有细胞中的全局视图 类型E）野生型RB等位基因的组织特异性失活， 将使用酵母FLP重组酶培育杂合小鼠 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具体功能。

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.