Genetic Variation in Murine Long Bone Growth and Development

描述（由申请人提供）：在肢体生长中有广泛的人类临床疾病。一些是由于单一基因，而另一些是复杂的，由于许多基因及其相互作用和环境。肢体生长变异的细胞和分子基础的纵向研究由于需要破坏性或终末取样来获得表型测量而受到阻碍，即使在模式生物中也是如此。我们建议测量小鼠长骨生长的遗传变异、相关的组织形态学特征和基因表达，以确定肢体生长变异背后的遗传和生理过程。这些研究将在LGXSM重组近交系（Rl）的动物身上进行。先前对这些菌株F2交叉的图谱研究发现了17个影响成人长骨长度的基因组位置。然而，这些早期的研究并没有确定哪个发育时期或生理过程对肢体长度的变化负责。我们将绘制Rl菌株的肢体生长qtl，因为这允许在相同基因型的动物的一系列连续年龄上收集需要末端准备的详细表型。因此，我们将能够获得特定基因型肢体生长特征的“纵向”数据。在Rl菌株中定位肢体生长qtl将确定影响长骨生长及其相关生理和分子过程的基因组区域至基因组的15 cM区域。我们将这些qtl在LG/J和SM/J反复杂交形成的高级交叉株系（Al）中精细定位到F32代。在这一点上，他们将积累16倍的重组产生在最初的F2交叉允许16倍的基因组定位分辨率（亚厘米尺度）。定位候选基因将在亚cm QTL支持区进行鉴定，并评估亲本系之间的序列和表达差异。这些实验的结果将使我们更好地理解肢体生长变异的遗传、分子和细胞过程，并对我们对生长病理的理解产生影响。

DESCRIPTION (provided by applicant): There are a wide range of human clinical disorders in limb growth. Some are due to single genes while others are complex, due to many genes and their interactions with each other and the environment. Longitudinal studies of the cellular and molecular bases for variation in limb growth are hampered by the need for destructive or terminal sampling to obtain phenotypic measures, even in model organisms. We propose to measure genetic variation in long bone growth, associated histomorphological features, and gene expression in mice in order to identify the genetic and physiological processes underlying limb growth variations. These studies will be carried out with animals from the LGXSM Recombinant Inbred (Rl) strains. Previous mapping studies in the F2 intercross of these strains uncovered 17 genomic locations affecting adult long bone length. However, these earlier studies do not identify which developmental periods or physiological processes are responsible for variations in limb length. We will map limb growth QTLs in the Rl strains because this allows the collection of detailed phenotypes requiring terminal preparations at a series of consecutive ages on animals of identical genotype. Thus, we will be able to obtain "longitudinal" data for limb growth traits for specific genotypes. Mapping limb growth QTLs in the Rl strains will identify genomic regions affecting long bone growth and its associated physiological and molecular processes to 15 cM regions of the genome. We will fine-map these QTLs in the Advanced Intercross (Al) line formed by repeatedly intercrossing LG/J and SM/J strains to the F32 generation. At this point they will have accumulated 16x the recombination generated in the original F2 intercross allowing for 16x the genomic mapping resolution (sub-cM scale). Positional candidate genes will be identified within the sub-cM QTL support regions and evaluated for sequence and expression differences between the parental lines. The outcome of these experiments will be a better understanding of the genetic, molecular, and cellular processes responsible for variation in limb growth with consequences for our understanding of pathologies of growth.