The Role of TGF-Beta3 in Palatogenesis

描述（由申请人提供）：腭裂是人类最常见的出生缺陷之一。我们和其他人已经表明，转化生长因子-3（TGF-3）在小鼠和人类的腭上皮融合中起着关键作用。Tgf失败-？3信号传导导致腭内侧边缘上皮不能消失的状况，并且随后完全生长的腭架不能融合。在该资助的前几年，我们已经表明，TGF-β信号是必要的腭上皮和腭间充质适当的腭架生长，图案和融合。因此，我们的研究结果表明，TGF-β 3在腭发育过程中的作用比以前认为的更广泛，更复杂。基于最近的研究结果和我们的初步数据，我们已经制定了一个总体假设，具体的，模块化的，长距离的调节元件负责靶向TGF <$3表达的融合前腭上皮。反过来，这种上皮特异性的TGF-β 3表达诱导了腭上皮中的Smad 4依赖性（典型）和Smad 4非依赖性（非典型）信号传导事件，这些事件与间充质TGF-β 3信号传导一起，是成功的腭融合所需的。在具体的目标1中，我们提出了测试的假设，即在腭内侧缘上皮细胞的TGF β 3的转录调节的远程5'和/或3'增强子。在具体的目标2中，我们建议测试的假设，TGF-β激活的激酶-1（Tak 1）的功能与Smad 4介导的信号通路，以诱导TGF-β 3诱导的细胞周期停滞和随后的细胞凋亡腭上皮细胞。在具体的目标3中，我们提出测试的假设，即在Tgfb 3无效突变体，TGF-β和Notch信号之间的不平衡导致细胞周期抑制剂的表达减弱，最终导致腭裂，最后，在具体的目标4中，我们提出测试的假设，TGF-β 3通过调节适当的模式化融合前腭架腭间充质发挥了以前意想不到的作用。我们独特的实验模型和最先进的策略将使我们能够定义在腭发育过程中的经典和非经典TGF-β信号传导的作用。总的来说，拟议的实验可能是至关重要的，在试图了解人类腭裂综合征的分子基础。

DESCRIPTION (provided by applicant): Cleft palate is among the most common birth defects in humans. We and others have shown that transforming growth factor-¿3 (Tgf-¿3) plays a critical role in palatal epithelial fusion both in mice and in humans. Failure in Tgf-¿3 signaling leads to a condition in which the palatal medial edge epithelium fails to disappear, and subsequently fully- grown palatal shelves fail to fuse. During previous funding years of this grant, we have shown that Tgf-¿ signaling is required both in the palatal epithelium and in the palatal mesenchyme for appropriate palatal shelf growth, patterning and fusion. Consequently, our results suggest that the role of Tgf-¿3 during palatogenesis is broader and more complex than previously thought. Based on the recent findings and our preliminary data, we have formulated an overall hypothesis that specific, modular, long-distance regulatory elements are responsible of targeting Tgf¿3 expression to the prefusion palatal epithelium. This epithelial-specific expression of Tgf¿3, in turn, induces both Smad4-dependent (canonical) and Smad4-independent (non-canonical) signaling events in the palatal epithelium that are together with the mesenchymal Tgf-¿3 signaling, required for successful palatal fusion. In specific aim 1, we propose to test the hypothesis that Tgf¿3 transcription in palatal medial edge epithelial cells is regulated by distant 5' and/or 3' enhancers. In specific aim 2, we propose to test the hypothesis that Tgf-¿-activated kinase-1 (Tak1) functions together with the Smad4-mediated signaling pathway to induce Tgf-¿3-induced cell cycle arrest and subsequent apoptosis in palatal epithelial cells. In specific aim 3, we propose to test the hypothesis that in Tgfb3 null mutants, imbalance between Tgf-¿ and Notch signaling leads to an attenuated expression of cell cycle inhibitors ultimately resulting in cleft palate, and finally, in specific aim 4, we propose to test the hypothesis that Tgf-¿3 plays a previously unexpected role in the palatal mesenchyme by regulating appropriate patterning of prefusion palatal shelves. Our unique experimental models and state-of-art strategy will allow us to define to the role of canonical and non-canonical Tgf-¿ signaling during palatogenesis. Collectively, the proposed experiments are likely to be of critical importance in attempting to understand the molecular basis of the cleft palate syndrome in humans.