GENETIC MODIFIERS OF TGF BETA 1 ACTION IN VIVO

转化生长因子β 1 （tgfβ 1）基因失活导致血管生成和造血缺陷，从而导致产前死亡。这种表型的外显率取决于遗传背景。一个主要的基因修饰子tgfmod1在控制tgfbet1 -/-胚胎致死率的外显率中占50%以上。这个项目的总体目标是确定tgfmod1。将采用遗传克隆和定位克隆相结合的方法。tgfmod1的鉴定将为我们了解体内胚胎血管生成和造血，以及TGFbeta1对这些过程的调控做出重大贡献。此外，它将测试克隆胚胎致死性表型遗传修饰因子的一般方法，其中许多已经在纯合基因敲除小鼠的一代中被发现。TGFbeta1与许多人类疾病有关，包括遗传性出血性毛细血管扩张（HHT）、癌症、病理性血管生成、动脉粥样硬化、炎症、骨质疏松、纤维化、伤口愈合和肾小球肾炎。然而，这些疾病表型的严重程度，包括单基因疾病，HHT，是非常可变的，这表明存在修饰基因性状。因此，鉴定可以改变由tgf - β错误调节引起的疾病的发生率和严重程度的基因对普通医学具有价值。tgfmod1将明确定位到大约0.5cM，使用我们的互惠同源小鼠面板，以及经过验证的功能基因测试杂交。将生成跨越这一关键图谱区域的BAC contig，并使用比较基因组测序和大量DNA序列分析软件工具来识别BAC contig中的每个基因。候选基因将根据其精细的图谱位置和基因表达模式进行选择。候选基因的功能多态性将通过各种分子多态性检测技术、DNA测序、RNA和蛋白质分析来搜索。tgfmod1的身份将通过几个小鼠品系的基因型/表型相关性以及包括转基因在内的功能分析来证实。

Inactivation of the transforming growth factor beta1 (TGFbeta1) gene causes defects in angiogenesis and haematopoiesis that lead to prenatal death. The penetrance of this phenotype depends on genetic background. A major genetic modifier, tgfmod1, contributes over 50% of the genetic in control of the penetrance of TGFbeta1-/-embryo lethality. The overall goal of this project is to identify tgfmod1. A combined genetic and positional cloning approach will be taken. The identification of tgfmod1 will make a significant contribution to our understanding of embryonic angiogenesis and hematopoiesis in vivo, as well as that of TGFbeta1 regulation of these processes. Moreover, it will test the general approach of cloning genetic modifiers of embryo-lethal phenotypes, many of which have been found during generation of homozygous gene knock out mice. TGFbeta1 is implicated in many human diseases, including hereditary haemorrhagic telangiectasia (HHT), cancer, pathological angiogenesis, atherosclerosis, inflammation, osteoporosis, fibrosis, wound healing and glomerulonephritis. However, the severity of these disease phenotypes, including the single gene disorder, HHT, is very variable, suggesting the existence of modifying gene traits. Identification of genes that can modify the incidence and severity of diseases caused by mis-regulation of TGFbeta is therefore of value to general medicine. tgfmod1 will be definitively mapped to approximately 0.5cM, using our panel of reciprocal congenic mice, together with a proven functional genetic test cross. A BAC contig will be generated that spans this critical map region, and comparative genomic sequencing, together with a large selection of DNA sequence analysis software tools, will be used to identify every gene within the BAC contig. Candidate genes will be selected on the basis of their fine map location and gene expression pattern. Functional polymorphisms within candidate genes will be searched for by various molecular polymorphism detection techniques, DNA sequencing and RNA and protein analysis. Identity of tgfmod1 will be confirmed by genotype/phenotype correlation in several mouse strains, and by functional analysis, including transgenesis.