Left-Right Axis Determination and Cardiac Development

左右轴测定和心脏发育

• 批准号: 6533457
• 负责人: ANN F RAMSDELL
• 金额: $ 29.02万
• 依托单位: UNIVERSITY OF SOUTH CAROLINA AT COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6533457
• 关键词: Xenopus; Xenopus oocyte; biological signal transduction; biomarker; cell cell interaction; congenital cardiovascular disorder; gene expression; gene induction /repression; gene targeting; growth /development; growth factor receptors; heart cell; high throughput technology; histogenesis; inhibin; molecular cloning; morphology; nonmammalian vertebrate embryology; orientation; protein tyrosine kinase; transforming growth factors; transplantation

DESCRIPTION (provided by applicant): The majority of complex congenital heart defects occur in individuals who are also afflicted by laterality disease, reflecting the extreme susceptibility of the developing heart to disturbances in left-right (LR) patterning processes. The objective of this proposal is to identify inductive mechanisms that generate the LR body plan and to elucidate how cardiac cells use this positional "blueprint" to develop LR asymmetries. With focus on receptors for the transforming growth factor-Beta superfamily, we have found that two Activin-Like Kinases--ALK2 and ALK4--are both necessary and sufficient for LR development of the heart (and other organs) in embryos of the frog, Xenopus Iaevis. Taking advantage of the range of experimental manipulations that is uniquely possible in Xenopus, we will test the hypothesis that ALK2 and ALK4 modulate cardiac LR development by playing pivotal roles in LR axis determination. Using both biochemical and loss-of-function analyses, Aim 1 will identify cell-cell signals important for LR axis formation by defining ligands for the ALK pathways. Using classic transplantation and co-culture assays, Aim 2 will position ALK pathways in the context of cell-cell interactions already known to be important for LR patterning by determining whether ALKs relay positional signals to the midline. Because many of the molecules involved in midline specification and other LR relay interactions are not known, Aim 3 will fill in some of these gaps by identifying genes that function upstream, downstream, or within ALK pathways. This will be accomplished by performing a high throughput expression cloning screen in which new laterality genes already have been, and will continue to be, identified by the applicant. Using in vivo lineage labeling, Aim 4 will address how cardiac cells utilize LR patterning information by determining whether ALK signaling culminates in specific asymmetric cell contributions from the paired left and right heart fields to different segments of the "straight" heart tube. Together, our results will contribute new knowledge that is necessary to accelerate progress in the intersecting fields of embryonic heart formation and vertebrate LR development. The long-term significance of the work will be to identify genes and inductive processes that may result in congenital cardiac (and other) LR defects if affected by genetic or environmental perturbations.

描述（由申请人提供）：大多数复杂先天性心脏缺陷发生在也患有偏侧性疾病的个体中，反映了发育中的心脏对左右（LR）模式过程中的干扰的极端敏感性。这个建议的目的是确定诱导机制，产生LR的身体计划，并阐明心脏细胞如何使用这个位置的“蓝图”，以发展LR的不对称。随着对转化生长因子β超家族受体的关注，我们发现两种激活素样激酶-ALK 2和ALK 4-对于青蛙（非洲爪蟾）胚胎中心脏（和其他器官）的LR发育都是必要和充分的。利用在非洲爪蟾中独特的实验操作范围，我们将测试ALK 2和ALK 4通过在LR轴确定中发挥关键作用来调节心脏LR发育的假设。使用生物化学和功能丧失分析，Aim 1将通过定义ALK途径的配体来识别对LR轴形成重要的细胞-细胞信号。使用经典的移植和共培养试验，Aim 2将通过确定ALK是否将位置信号传递到中线，在已知对LR模式化很重要的细胞-细胞相互作用的背景下定位ALK通路。由于参与中线特化和其他LR中继相互作用的许多分子尚不清楚，Aim 3将通过鉴定在ALK通路上游、下游或内部发挥作用的基因来填补其中一些空白。这将通过进行高通量表达克隆筛选来实现，其中申请人已经并将继续鉴定新的偏侧性基因。使用体内谱系标记，Aim 4将通过确定ALK信号传导是否在从配对的左和右心脏野到“直”心管的不同节段的特定不对称细胞贡献中达到高潮，来解决心脏细胞如何利用LR模式化信息。总之，我们的研究结果将有助于新的知识，这是必要的，以加快在胚胎心脏形成和脊椎动物LR发展的交叉领域的进展。这项工作的长期意义将是确定基因和诱导过程，如果受到遗传或环境扰动的影响，可能导致先天性心脏（和其他）LR缺陷。