RETINOL BINDING PROTEIN AND HEART DEVELOPMENT

描述(申请人的逐字描述)：本实验室的目标 是确定早期分泌的支持和规范因素 胚胎内胚层细胞，调节心脏发育。我们最近做了 确定内胚层强烈表达维生素A转运蛋白 转甲状腺素(TTR)和视黄醇结合蛋白(RBP)。TTR和TTR的测绘地点 RBP蛋白和mRNA在胚胎中的表达已经揭示了这些因素 一般与心脏形成区域有关，并与明确的 尤其是心肌结构。因为发育中的心脏高度 视黄醇的敏感代谢产物，特别是维甲酸(RA) RBP来源于内胚层和最终心肌的假说 细胞是调节视黄醇向心肌结构输送所必需的 他们的发展。通过同源重组删除RBP基因将 用于在各种小鼠胚胎模型中检验这一假说。(1) 第一个目标将使用靶向ES细胞来检查RBP-/-的效果 类胚体心脏发生过程中的突变。(2)第二个目标是 利用纯合子缺陷RBP-/-ES制备的嵌合胚胎 具有桑蚕期ROSA26野生型胚胎的细胞，这些胚胎结构性地表达 B-半乳糖苷酶。RBP-/-突变细胞从胚胎心脏中的排斥 如果他的器官是嵌合体的话就意味着自主需求 RBP基因在心脏发育中的作用。(3)第三个目标将直接 通过生产确定RBP基因对心脏发育的必要性 利用四倍体技术从RBP-/-ES细胞中获得RBP-/-胚胎 聚合。最后，(4)一组RBP缺失的小鼠将被准备延伸 这些研究。这些实验的结果将阐明 发育中的心肌对维生素A及其受体水平的调控 产品维甲酸(RA)。这些发现将进一步有助于 先天性心脏缺陷的发病机制探讨 作为成人心肌不能修复的原因。

DESCRIPTION (the applicant's description verbatim): This laboratory's objective is to identify support and specification factors that are secreted by early embryonic endoderm cells, which regulate heart development. We have recently determined that endoderm strongly expresses the vitamin A transport proteins transthyretin (TTR) and retinol binding protein (RBP). Mapping sites of TTR and RBP protein and mRNA expression in the embryo has revealed that these factors are associated with the heart forming region in general and with definitive myocardial structures in particular. Because the developing heart is highly sensitive metabolic products of retinol, particularly retinoic acid (RA), it is hypothesized that RBP derived from both endoderm and definitive myocardial cells is necessary to regulate retinol delivery to myocardial structures during their development. Deletion of the RBP gene via homologous recombination will be used to test this hypothesis in a variety of murine embryonic models. (1) The first aim will use targeted ES cells to examine the effect of the RBP-/- mutation during cardiogenesis in embryoid bodies. (2) The second aim will utilize chimeric embryos prepared by combining homozygous-deficient RBP-/- ES cells with morula-stage Rosa26 wild-type embryos that constitutively express b-galactosidase. The exclusion of RBP-/- mutant cells from the heart of embryos whose organs are otherwise chimeric would indicate an autonomous requirement for the RBP gene in heart development. (3) The third aim will directly establish the necessity of the RBP gene for heart development by producing RBP-/- embryos from RBP-/- ES cells using the technique of tetraploid aggregation. Finally, (4) a line of RBP-null mice will be prepared to extend these studies. Results from these experiments will elucidate the dependence of the developing myocardium on carefully regulated levels of vitamin A and its product, retinoic acid (RA). These findings will further contribute to an elucidation of the mechanisms which underlie congenital heart defects as well as the reasons why the adult myocardium is incapable of repair.