ANALYSIS OF INSERTIONAL MUTATIONS IN TRANSGENIC MICE

发育生物学的主要目标之一是阐明 控制不同细胞类型生成的分子机制 未指明的前体。详细了解这些机制将 不仅帮助我们理解正常个体发育的基本原则， 也解释，并最终纠正，发展的情况下， 出轨导致疾病基本螺旋环螺旋拉链 转录因子Mitf由一个基因编码，该基因在啮齿动物中的突变 或人可能会导致异常的形成神经嵴源性 和神经上皮来源的黑素细胞以及伴随的皮肤 色素沉着缺陷、耳聋和眼睛畸形，可能导致 视网膜变性在小鼠中，Mitf突变似乎具有不同的 对神经嵴衍生的和神经上皮衍生的黑素细胞的作用。 无论是在体内还是在培养中，神经嵴衍生的突变细胞都被阻断， 在早期的前黑色素细胞阶段发育并可能死亡。在 相比之下，突变的神经上皮衍生细胞通常成为 视网膜色素细胞存活，显示出 黑色素细胞特异性基因，并可能最终发展成神经视网膜 细胞因此，Mitf似乎是一个调节器的发展命运， 至少有两种不同的细胞谱系以确定它是否具有 重新指定细胞命运的能力，这些细胞通常不会成为 黑素细胞，我们产生了转基因小鼠与无处不在的诱导Mitf 表达，正在产生其中Mitf表达的小鼠的过程中， 专门针对发育中的视网膜，并能够表达 视网膜和神经嵴细胞培养中的异位Mitf。分析 在这样的操纵细胞中的靶基因表达将帮助我们 了解导致黑素细胞形成的事件顺序。到 确定突变神经嵴衍生细胞的确切命运， 我们已经开始培育转基因小鼠， 成黑素细胞及其衍生物被永久标记。

One of the main goals of developmental biology is to elucidate the molecular mechanisms that govern the generation of distinct cell types from unspecified precursors. A detailed knowledge of these mechanisms will not only help us understand fundamental principles of normal ontogeny but also explain, and ultimately correct, instances where development has derailed and disease has resulted. The basic-helix-loop-helix-zipper transcription factor Mitf is encoded by a gene whose mutations in rodents or man may lead to abnormalities in the formation of neural crest-derived and neuroepithelial-derived melanocytes and to the concomitant skin pigmentation defects, deafness, and eye malformations that may lead to retinal degeneration. In mice, Mitf mutations appear to have different effects on neural crest-derived and neuroepithelium-derived melanocytes. Both in vivo and in culture, neural crest-derived mutant cells are blocked in their development at an early, pre-melanoblastic stage and may die. In contrast, mutant neuroepithelial-derived cells which normally become retinal pigment cells survive, display dysregulated expression of melanocyte-specific genes, and may finally develop into neuroretinal cells. Thus, Mitf appears to be a regulator of the developmental fate of at least two distinct cell lineages. To determine whether it has the capacity to respecify the fate of cells not normally destined to become melanocytes, we generated transgenic mice with ubiquitously inducible Mitf expression, are in the process of generating mice in which Mitf expression is specifically targeted to the developing retina, and are able to express Mitf ectopically in retinal and neural crest cell cultures. The analysis of target gene expression in such manipulated cells will help us understand the sequence of events that lead to melanocyte formation. To determine what is the precise fate of mutant neural crest-derived cells, we have initiated the generation of transgenic mice in which early melanoblasts and their derivatives are permanently marked.