MOUSE MODELS OF EARLY INTESTINAL NEOPLASIA

描述：（改编自研究者摘要） 异常干细胞增殖（分裂和克隆数量） 扩张）可能是一个主要的风险因素， 肠道肿瘤发生的最早表现。然而，干细胞 因为它们数量少， 在众多的终末分化上皮细胞中， 细胞这项提案将重点放在老鼠的肠道干细胞上 DNA错配修复（MMR）缺乏MMR导致 突变率增加了大约100倍， 两种互补的方法。一、茎的数量 细胞分裂可以从遗传学上估计， 微卫星（MS）基因座的体细胞突变。突变只能 在干细胞中积累，因为所有其他细胞在几天内就会丢失。 因此，所有上皮细胞基本上反映了上皮细胞的基因型。 干细胞，这反过来应该是一个功能的数量， 分裂初步数据表明，肠道MS位点，如 通过计算机模拟预测，变得越来越多元， 年龄第二，基因突变的频率和模式， 干细胞扩增将从原位损失中扣除， 内源性组织学标志物（lacZ）由于突变。越大 在缺乏的背景下预期的自发突变数量 MMR应该增加这种良好建立的组织学检查的效率， 法干细胞分裂的数量和它们的模式 在具有Pms 2生殖系突变的小鼠中将观察到扩增， Mlh 1或Apc，以及饮食（高脂肪/低钙和热量限制） 从而增加或减少瘤形成的频率。这些研究 将决定目前干细胞的隐性变异 分裂率或扩张模式与 肠肿瘤

DESCRIPTION: (adapted from the investigator's abstract) Abnormal stem cell proliferation (numbers of divisions and clonal expansion) is likely a major risk factor and an early if not the earliest manifestation of intestinal tumorigenesis. However, stem cells are difficult to study since they are small in number and hard to identify among the more numerous terminally differentiated epithelial cells. This proposal will focus on the intestinal stem cells of mice deficient in DNA mismatch repair (MMR). The lack of MMR results in approximately 100-fold increases in mutation rates which increases the feasibility of two complementary approaches. First, the number of stem cell divisions can be estimated genetically from the accumulation of somatic mutations in microsatellite (MS) loci. Mutations can only accumulate in stem cells since all other cells are lost within days. Therefore, all epithelial cells essentially reflect the genotypes of the stem cells, which in turn should be a function of the numbers of their divisions. Preliminary data demonstrate that intestinal MS loci, as predicted by computer simulations, become progressively polymprphic with age. Second, frequencies of mutation and patterns of otherwise occult stem cell expansions will be deducted from the in situ loss of endogenous histologic markers (lacZ) due to mutation. The greater numbers of spontaneous mutations expected in the setting of deficient MMR should increase the efficiency of this well established histological technique. The numbers of stem cell divisions and their patterns of expansion will be observed in mice with germline mutations in Pms2, Mlh1, or Apc, and on diets (high fat/low calcium and calorie restricted) which increase or decrease the frequencies of neoplasia. These studies will determine whether currently occult alterations in stem cell division rates or in patterns of expansion are associated with intestinal neoplasia.