ANALYSIS OF INSERTIONAL MUTATIONS IN TRANSGENIC MICE

将转基因插入小鼠基因组偶尔会导致 破坏重要的内源基因。 当繁殖到转基因 纯合性，这样的转基因小鼠可以表现出突变表型 这是由内源基因的不正常功能引起的。 我们有 遇到了两种不同的插入突变体， 异常 一个品系的小鼠（品系2627）携带大约15个 11号染色体上的转基因拷贝。 该品系的表型为 特征为半椎骨，椎源性隐性脊柱裂， 椎体融合和短而扭曲的尾巴 该表型 让人想起波动的，Paxl配对盒中的突变 由2号染色体上的pax 1基因编码的蛋白质。自从Paxl和基因 将转基因插入映射到不同的染色体，但产生 当突变时，表型相似，这两个基因可能 产物沿着相同的代谢途径起作用。 为了克隆内源性 基因在11号染色体上，我们已经在λ噬菌体中制备了基因组文库 目前正在对它们进行DNA序列筛查 位于转基因的侧翼。 第二系转基因小鼠（VGA 9）携带约50个拷贝， 6号染色体上的转基因纯合子转基因显示出完全的 皮肤脱落，色素沉着完全或接近完全脱落， 小眼症，以及至少50 dB的严重听力缺陷， 通过脑干听觉诱发电位测量进行分析， 与来自LMO，NIDCD的Kenneth Grundfast博士合作。 的 听力缺陷可能是由于发育不足的结果， 耳蜗的血管纹，中间细胞层 它的黑色素生成细胞消失了 因此，插入影响， 在其他细胞谱系中，神经嵴的正常发育 衍生的色素细胞。 它是等位基因， 到，突变mi（未克隆），并与其他两个良好的共享功能 特征性突变，W（受体激酶c-kit中的突变），和 S/（生长因子钢中的突变）。 表型的重叠 表明这三个突变和VGA 9插入影响基因， 相同的代谢途径，特别感兴趣的是连接 VGA 9和人类瓦登伯格综合症之间的联系 以遗传性耳聋和色素异常为特征。 识别转基因中受影响的基因可能会提供分子生物学证据。 探针有助于描述患有这种综合征的患者， 了解这种疾病的发病机制。

Insertion of transgenes into the mouse genome occasionally results in disruption of important endogenous genes. When bred to transgene homozygosity, such transgenic mice may exhibit mutant phenotypes resulting from improper functioning of the endogenous gene. We have encountered two different insertional mutants exhibiting developmental abnormalities. One line of mice (line 2627) harbors approximately 15 copies of a transgene on chromosome 11. The phenotype of this line is characterized by hemivertebrae, vertebrogenic spina bifida occculta, fusions of vertebral bodies, and short, kinky tails. This phenotype is reminiscent of undulated, a mutation in the paired-box of the Paxl protein encoded by the paxl gene on chromosome 2. Since Paxl and the gene with the transgene insertion map to different chromosomes, yet produce similar phenotypes when mutated, it is possible that the two gene products act along the same metabolic pathway. To clone the endogenous gene on chromosome 11, we have prepared genomic libraries in lambda phage and are currently screening them for the presence of DNA sequences flanking the transgene. A second line of transgenic mice (VGA 9) harbors approximately 50 copies of a transgene on chromosome 6. Homozygous transgenics show a complete loss of skin, complete or near-complete loss of eve pigmentation, microphthalmia, and a severe hearing deficiency of at least 50 dB as analyzed by brain stem auditory evoked potential measurements done in collaboration with Dr. Kenneth Grundfast from the LMO, NIDCD. The hearing deficiency may be the consequence of an underdevelopment of the stria vascularis of the cochlea where the intermediate cell layer with its melanin-producing cells is missing. Thus, the insertion affects, among other cell lineages, the proper development of the neural crest-- derived pigment cells. It is allelic with, and phenotypically similar to, the mutation mi (not cloned), and shares features with two other well characterized mutations, W (a mutation in the receptor kinase c-kit), and S/ (a mutation in the growth factor steel). The overlap of phenotypes suggests that these three mutations and the VGA 9 insertion affect genes of the same metabolic pathway, Of particular interest is the connection between VGA 9 and the human Waardenburg syndrome, a syndrome characterized by hereditary deafness and pigment abnormalities. Identifying the gene affected in the transgenics may provide molecular probes useful to characterize patients with this syndrome, and may help to understand the pathogenesis of this disease.