Role of BMP and FGF signaling during limb development

BMP 和 FGF 信号在肢体发育过程中的作用

• 批准号: 8349034
• 负责人: MARK B LEWANDOSKI
• 金额: $ 40.3万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8349034
• 关键词: Address; Adult; Affect; Alleles; Animals; Anterior; Apoptosis; Behavior; Biology; Bone Morphogenetic Proteins; Cell Death; Cells; Cellular biology; Collaborations; Data; Development; Digit structure; Disease; Distal; Down-Regulation; Effector Cell; Elements; Embryo; Embryonic Development; Experimental Genetics; Family; Fibroblast Growth Factor; Forelimb; Gastrointestinal Neoplasms; Gene Silencing; Genes; Genetic; Goals; Growth; Heart; Hindlimb; Internet; Knock-in Mouse; Learning; Ligands; Limb Bud; Limb Development; Limb structure; Link; Malignant Neoplasms; Malignant neoplasm of prostate; Mediating; Mesenchymal; Mesenchyme; Metastatic Neoplasm to the Bone; Modeling; Molecular; Mus; Nature; Normal Cell; Osteogenesis; Pathway interactions; Pattern; Pelvic Girdle; Population; Positioning Attribute; Protein Family; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Skeleton; Structure; Surface Ectoderm; Testing; Work; beta catenin; bone morphogenetic protein receptors; human DICER1 protein; insight; interest; malignant breast neoplasm; novel; progenitor; receptor; skeletal; tumor

In prior efforts, we contributed to a large body of work that described an essential role for Fibroblast Growth Factor (FGF) signaling during limb development by examining mice lacking genes that encode FGF ligands and receptors (Lewandoski et al. 2000 Nature Genetics 28:167, Sun et al 2000 Nature Genetics 25: 6, (Verheyden et al 2005Development 132:4235). Another important signaling pathway during limb development controlled by Bone Morphogenetic Proteins (BMPs), which arguably controls all aspects of limb outgrowth: early patterning in all three axes, programmed cell death and bone formation. Therefore we have set ourselves the task to understand how BMP and FGF signaling pathways interact during limb development. Because of our general interest in limb development we have participated in a collaboration that demonstrated that Islet1-mediated activation of the beta-catenin pathway is necessary for hindlimb initiation (in press). In second collaboration it was determined that the Dicer gne product is required for the proper positioning of the hindlimb bud along the anterior -posterior body axis (Zhang, Z. et al 2011 Dev Biol 351, 254). Finally, also in a collaborative study, we determined that all of the elements of the pelvic girdle and its surrounding perichondrium are Tbx4-derived. Also, although Tbx4 is thought to be associated primarily with the hindlimb, we characterized two forelimb expression domains in a study in which we reexamined the expression of Tbx4 in detail and also traced the fates of Tbx4-expressing cells with a previously generated, but incompletely characterized, allele of Tbx4 knocked in Cre allele (Naiche A et al 2001 Dev Dyn in press). In current work, we are studying the role of BMP signaling as effectors of normal programmed cell death that occurs in mesenchymal interdigit cells, thus removing them and sculpting the final digit pattern in animals that are born without webbed limbs. In previous work produced genetic evidence for a novel model in which the surface ectoderm must receive a BMP signal, resulting in down regulation of Fgfs which in turn induces apoptosis of the underlying mesenchyme (Pajni-Underwood S. et al 2007 Development 134: 2359). Thus we demonstrated that BMPs control programmed cell death indirectly, by regulating FGF signaling. However, it is important to emphasize that this insight does not exclude a direct role for BMP signaling in controlling cell death in the developing limb. Therefore we are extended these studies by studying the role of BMP and FGF signaling in various aspects of limb development using mouse lines that express Cre in specific region of the developing limb. For example the only way to test the hypothesis that BMPs act as direct effectors of cell death is to inactivate BMPs receptors only in the lineage that undergoes cells death, without affecting FGF expression in nearby cells. We have achieved this using new Cre lines that allow Cre-mediated gene inactivation in these lineages. With these lines are asking: are BMPs are direct effectors of normal programmed cell death? If not, how is programmed cell death controlled? If so, how do BMPs achieve this endpont? In another study, we have uncovered an important node of signaling between FGFs and BMP that is essential for normal development of the limb skeleton. Our previous work, cited above, demonstrates that specific FGFs, secreted from a distal structure in the limb bud, regulate the normal outgrowth and patterning of the limb. In current work, we are generating genetic evidence that BMP signaling to the progenitor population of the skeletal elements regulates this FGF signal by controlling the expression of an FGF antagonist. This linking of the two signaling pathways is not only a unique insight into how the limb is patterned but may provide a model for how the two pathways interact in other developmental contexts or during cancer.

在先前的努力中，我们通过检查缺乏编码成纤维细胞生长因子（FGF）配体和受体的基因的小鼠，对描述成纤维细胞生长因子（FGF）信号传导在肢体发育期间的重要作用的大量工作做出了贡献（Lewandoski等，2000 Nature Genetics 28：167，Sun等，2000 Nature Genetics 25：6，（Verheyden等，2005 Development 132：4235）。肢体发育过程中的另一个重要信号通路由骨形态发生蛋白（BMPs）控制，它可以控制肢体生长的所有方面：所有三个轴的早期模式，程序性细胞死亡和骨形成。因此，我们已经为自己设定了任务，以了解BMP和FGF信号通路在肢体发育过程中如何相互作用。由于我们对肢体发育的普遍兴趣，我们参与了一项合作，该合作证明了Islet 1介导的β-连环蛋白通路的激活对后肢起始是必要的（出版中）。在第二次合作中，确定了Dicer gne产品对于后肢芽沿着前后体轴的正确定位是必需的（Zhang，Z.等人2011 Dev Biol 351，254）。最后，同样在一项合作研究中，我们确定骨盆带及其周围软骨膜的所有元素都是Tbx 4衍生的。此外，尽管Tbx 4被认为主要与后肢相关，但我们在一项研究中表征了两个前肢表达结构域，在该研究中我们详细地重新检查了Tbx 4的表达，并且还追踪了表达Tbx 4的细胞的命运，该细胞具有先前产生的但未完全表征的敲入Cre等位基因的Tbx 4等位基因（Naiche A等人，2001 Dev Dyn，出版中）。在目前的工作中，我们正在研究BMP信号传导作为间充质趾间细胞中发生的正常程序性细胞死亡的效应器的作用，从而去除它们并在出生时没有蹼状肢的动物中塑造最终的数字模式。在先前的工作中，产生了新模型的遗传证据，其中表面外胚层必须接收BMP信号，导致Fgfs的下调，这反过来诱导下层间充质的细胞凋亡（Pajni-Underwood S.等人2007 Development 134：2359）。因此，我们证明BMPs通过调节FGF信号间接控制程序性细胞死亡。 然而，重要的是要强调，这一认识并不排除BMP信号在控制发育肢体细胞死亡中的直接作用。因此，我们通过使用在发育肢体的特定区域中表达Cre的小鼠品系研究BMP和FGF信号传导在肢体发育的各个方面中的作用来扩展这些研究。例如，检验BMPs作为细胞死亡的直接效应物的假设的唯一方法是仅在经历细胞死亡的谱系中抑制BMPs受体，而不影响附近细胞中的FGF表达。我们已经实现了这一点，使用新的Cre线，使Cre介导的基因失活在这些谱系。有了这些线是问：骨形成蛋白是正常的程序性细胞死亡的直接效应？如果不是，那么程序性细胞死亡是如何控制的呢？如果是这样，BMP如何实现这一目标？ 在另一项研究中，我们发现了FGF和BMP之间的一个重要信号节点，这对肢体骨骼的正常发育至关重要。我们之前的工作，上面引用的，证明了特定的FGF，从肢芽的远端结构分泌，调节肢体的正常生长和图案。在目前的工作中，我们正在产生遗传学证据，BMP信号传导到骨骼元件的祖细胞群体通过控制FGF拮抗剂的表达来调节FGF信号。这两种信号通路的联系不仅是对肢体如何形成的独特见解，而且可能为这两种通路在其他发育环境或癌症期间如何相互作用提供模型。