MOLECULAR GENETICS OF OSTEOPENIA IN THE SENESCENCE ACCELERATED MOUSE

加速衰老小鼠骨质减少的分子遗传学

• 批准号: 6098703
• 负责人: ROBERT S REIS
• 金额: $ 19.64万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2000-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6098703
• 关键词: aging; animal old age; blood cell count; bone density; denaturing gradient gel electrophoresis; genetic library; genetic markers; genetic strain; genotype; laboratory mouse; linkage mapping; longitudinal animal study; murine leukemia virus; osteoblasts; osteopenia; phenotype; physiologic bone resorption; polymerase chain reaction; quantitative trait loci; single strand conformation polymorphism

Bone density is a highly heritable quantitative trait in humans, declines markedly with senescence, and is the major determinant of skeletal fragility in osteoporosis. The SAM/P-6 mouse displays an early-onset osteopenic phenotype featuring diminished peak bone mineral density, declining further after maturity, and markedly decreased numbers of osteoblast progenitors in bone marrow. This progressive osteopenia is also highly heritable, with about 60% of the variation in bone density in interstrain cross progeny attributable to genetic factors. It is proposed to identify genetic loci contributing to osteopenia and associated parameters, by standard gene-mapping procedures developed for quantitative trait loci, coupled to an improved technique for assessing bone mineral density in vivo. Crosses will be constructed between SAM/P-6 and a control line with normal-bone-density, SAM/R-1. The polygenic basis of osteopenia in P-6 mice, and the extent of its heritability, will be assessed for several indices of normal osteogenesis. Microsatellite- repeat markers which distinguish between the P-6 and R-1 genomes will be used to localize genes contributing to osteopenia, by maximum-likelihood analysis of genotype and bone-density data for the genetically variable F(2) progeny of a P-6 times R-1 cross. If several quantitative trait loci are identified which correlate with bone density, they will be tested for interactions in generating osteopenia. Endogenous retroviral integration sites will be probed to determine whether any co-localize with osteopenia loci, implying insertional mutation of the implicated genes and enabling their rapid isolation. To test the roles of individual osteopenia loci, and to allow their high-resolution mapping, congenic lines will be constructed which contain such loci in the genetic background of the contrasting-phenotype parent. Limited back-crossing strategies, and congenic strains based on tracking osteopenia-associated phenotypes and genotypes at the implicated loci, will also be employed to facilitate detailed mapping. The regions thus identified will be analyzed for previously-implicated "candidate genes" and for sequence identity to transcripts in a cDNA library prepared from bone marrow cells. Aided by high-density genetic maps being constructed for human and mouse genomes, which are largely congruent, localization of osteopenia genes in SAMP/P-6 mice should expedite the search for human genes underlying osteoporosis.

骨密度是人类高度可遗传的数量性状，下降 明显伴随着衰老，是骨骼的主要决定因素 骨质疏松症的脆弱性。SAM/P-6小鼠表现出早发性 以峰值骨密度降低为特征的骨量减少表型， 成熟后进一步下降，并显著减少数量 骨髓中的成骨祖细胞。这种进行性骨量减少症是 也是高度可遗传的，大约60%的骨密度变异在 可归因于遗传因素的品系间杂交后代。有建议说 确定导致骨质疏松症的遗传基因和相关基因 参数，通过为定量基因作图开发的标准程序 性状基因座，加上一种改进的骨矿物质评估技术 体内密度。将在SAM/P-6和 正常骨密度对照组，SAM/R-1。的多基因基础 P-6小鼠的骨量减少及其遗传性的程度将是 评估正常成骨的几个指标。微卫星- 区分P-6和R-1基因组的重复标记将是 用于定位导致骨质疏松症的基因，极大可能 遗传变量的基因分型和骨密度数据分析 F(2)为P-6×R-1杂交后代。如果有几个数量性状基因座 被发现与骨密度相关的物质，将进行检测 骨质疏松症发生过程中的相互作用。内源性逆转录病毒整合 将对部位进行调查，以确定是否有任何与骨质疏松症共存的部位 基因座，暗示相关基因的插入突变和使能 他们的快速隔离。为了测试单个骨量减少基因座的作用， 为了实现高分辨率的作图，同源系将被 所构建的基因包含这些基因座的遗传背景 反差表型亲本。有限的回交策略，以及 基于追踪骨量减少相关表型的同源菌株和 相关基因座上的基因型别也将被用来促进 详细的映射。将对这样确定的区域进行分析 先前牵连的“候选基因”和序列同一性 从骨髓细胞制备的cdna文库中的转录本。协助者 正在为人类和小鼠基因组构建高密度遗传图谱， 与SAMP/P-6中骨量减少基因的定位大体一致 老鼠应该加快寻找导致骨质疏松症的人类基因。