Analysis of Cardiac Development in Ts65Dn Mice

Ts65Dn 小鼠心脏发育分析

基本信息

批准号：
7127747
负责人：
CLARA S MOORE
金额：
$ 18.99万
依托单位：
FRANKLIN AND MARSHALL COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-08-01 至 2010-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): PROJECT SUMMARY: Ts65Dn mice represent the best-characterized animal model for Down syndrome (DS). These mice carry the T65Dn marker chromosome, producing trisomy for a region of mouse chromosome 16 (MMU16) that includes orthologs of about 50% of the genes on human chromosome 21 (HSA21). Forty percent of DS individuals display congenital heart defects (CHD), and we hypothesize that the Ts65Dn mice will display phenotypes related to defective cardiac development. We have demonstrated that the transmission rate of segmental trisomy in Ts65Dn is near the expected 50% at birth, but declines to 34% of offspring by weaning, with selective loss of Ts65Dn neonates within 48 hours of birth. Gross anatomical and histological examination of cadavers indicates aortic arch and AV cushion related septal defects in Ts65Dn neonates. These observations support the hypothesis that one or more candidate genes for DS CHD occur within the trisomic region of Ts65Dn. We will examine genes contained in distal MMU16 and proteins normally expressed in the endocardial cushions to determine if the pathways of cell signaling and differentiation critical to normal cardiac septation are modulated by overexpression of the Ts65Dn genes. We plan to investigate the cardiac development of Ts65Dn mice through the following Specific Aims: 1. Determine the range of cardiac anomalies present in Ts65Dn embryos. Gross plus histological examination using light and scanning electron microscopy will be performed on embryonic hearts of the eupoid (wild type, wt) and trisomic siblings at critical stages of cardiac morphogenesis to determine the incidence and phenotypic range of cardiac defects in Ts65Dn offspring. 2. Analyze the process of epithelial to mesenchymal transformation (EMT), critical to AV endocardial cushion formation, in Ts65Dn transgenic hearts using an in vitro EMT/ migration assay. 3. Investigate the biochemical and molecular differences between Ts65Dn and wt cardiac tissues with emphasis on genes within the Ts65Dn region. Cardiac developmental gene markers and candidate DS CHD genes will be analyzed using in situ hybridization and immunohistology to determine the temporal- spatial patterns of gene and protein expression in endocardial cushions and derivative structures. RATIONALE: Mouse models are commonly used to analyze underlying genetic causes of human disease, as well as to identify the genes that are critical for normal mammalian development. Defining the dosage sensitive genes and the mechanisms by which their misexpression contributes to congenital heart defects in DS will provide insights into the roles of diploid genes during normal cardiac development and may suggest ameliorative strategies for congenital heart defects in DS or euploid individuals.

描述（由申请人提供）：项目摘要：Ts65Dn 小鼠代表了最具代表性的唐氏综合症 (DS) 动物模型。这些小鼠携带 T65Dn 标记染色体，产生小鼠 16 号染色体 (MMU16) 区域的三体性，其中包括人类 21 号染色体 (HSA21) 上约 50% 的基因的直系同源物。 40% 的 DS 个体表现出先天性心脏缺陷 (CHD)，我们假设 Ts65Dn 小鼠将表现出与心脏发育缺陷相关的表型。我们已经证明，Ts65Dn 节段性三体性的传播率在出生时接近预期的 50%，但断奶后下降至后代的 34%，且 Ts65Dn 新生儿在出生 48 小时内选择性丢失。尸体的大体解剖和组织学检查表明 Ts65Dn 新生儿存在主动脉弓和 AV 垫相关的间隔缺损。这些观察结果支持以下假设：DS CHD 的一个或多个候选基因出现在 Ts65Dn 三体区域内。我们将检查远端 MMU16 中包含的基因和通常在心内膜垫中表达的蛋白质，以确定对正常心脏间隔至关重要的细胞信号传导和分化途径是否受到 Ts65Dn 基因过度表达的调节。我们计划通过以下具体目标研究 Ts65Dn 小鼠的心脏发育： 1. 确定 Ts65Dn 胚胎中存在的心脏异常范围。使用光学和扫描电子显微镜对处于心脏形态发生关键阶段的真类（野生型，wt）和三体兄弟姐妹的胚胎心脏进行大体组织学检查，以确定 Ts65Dn 后代心脏缺陷的发生率和表型范围。 2. 使用体外 EMT/迁移测定分析 Ts65Dn 转基因心脏中上皮到间质转化 (EMT) 的过程，这对于 AV 心内膜垫的形成至关重要。 3. 研究 Ts65Dn 和 wt 心脏组织之间的生化和分子差异，重点关注 Ts65Dn 区域内的基因。将使用原位杂交和免疫组织学分析心脏发育基因标记和候选 DS CHD 基因，以确定心内膜垫和衍生结构中基因和蛋白质表达的时空模式。理由：小鼠模型通常用于分析人类疾病的潜在遗传原因，以及识别对正常哺乳动物发育至关重要的基因。定义剂量敏感基因及其错误表达导致 DS 先天性心脏缺陷的机制，将有助于深入了解二倍体基因在正常心脏发育过程中的作用，并可能提出针对 DS 或整倍体个体先天性心脏缺陷的改善策略。