Understanding WNT9A/FZD9 Trafficking and Signaling

细胞间信号传递是所有多细胞生命的基础。一个细胞分泌的信号分子是 能够通过与表面受体的相互作用与其他细胞进行交流，这些受体解释和 转换这些信号。其中一类分泌信号分子是由Wnt基因家族编码的。 这些蛋白质产物驱动过多的细胞过程，包括细胞对称性、增殖、组织 极性和干细胞维持。这种不同的过程发生在保守的细胞内机制来 对这些输出进行编程，表明需要在细胞膜水平上进行复杂的控制。至少部分 这种信号复杂性的调节在于编码特定配体的多个基因(哺乳动物中有19个) 和受体(哺乳动物为10个)。然而，始于关联的具体机制 膜上的各种配体和受体，并导致核转录活性 不完全理解。在这方面缺少的一个环节是破译受体复合体是如何 被细胞内化，它被贩运到哪里，以及这些事件如何导致不同的转录输出。 这种导致不同输出的配体-受体输入系统可能依赖于 受体复合体，以及信号的细胞背景。破译这一密码对我们理解 细胞是如何接收和传递特定信号的。这项提议旨在描述这一沟通的特点 在特定的Wnt信号受体复合体的运输和细胞核内转录的激活之间。 尽管已知Wnt配体与FrizzledFZD受体配对是转导 许多(如果不是大多数)Wnt信号，我们对特定Wnt/Fzd配对所通过的机制的理解 目前尚缺乏允许转录激活因子β-Catenin(β-CAT)进入细胞核的信号通路。我们开发了一部小说 通过荧光标记Wnt配体，FZD受体，研究这种性质的特定信号转导的系统， 以及转录激活剂β-CAT。这是基于我们之前的研究，这些研究表明 配体Wnt9a与受体FrizzledFzd 9b的精妙特异性配对，以及这种特异性 这种信号是由表皮生长因子受体(EGFR)传递的。这项提议旨在进一步 通过研究Wnt9a/Fzd9b受体在细胞内的转运来确定该受体的信号转导机制 复杂，并将其与β-CAT动作相结合。通过首先了解一个特定的WNT/FZD配对 建立特定的信号，我们可以生成一个模型，用于进一步测试不同类型的其他WNT/FZD络合物 蜂窝环境。此外，细胞信号事件经常跨越到其他途径；这些发现可能 当然会影响我们对其他受体-配体复合体如何在细胞中导致不同输出的理解。 PI拥有Wnt信号和细胞生物学方面的专业知识，以及指导学生 这些领域的出版物。这些项目的成功完成使PI和她的实验室成为 WNT信令领域，以及在该领域的长期成功。

Cell to cell signaling is fundamental to all multicellular life. Secreted signaling molecules from one cell are able to communicate with other cells through interaction with receptors on the surface, which interpret and transduce these signals. One such class of secreted signaling molecules is encoded by the Wnt gene family. These protein products drive a plethora of cellular processes, including cellular symmetry, proliferation, tissue polarity and stem cell maintenance. This variety of processes occurs using conserved intracellular machinery to program these outputs, indicating a need for complex control at the level of the cell membrane. At least part of the regulation of this signaling complexity lies in the multiple genes encoding specific ligands (19 in mammals) and receptors (10 in mammals). However, the specific mechanisms that start with the association of various ligands and receptors at the membrane, and lead to nuclear transcriptional activity are incompletely understood. One of the missing links in this aspect is to decipher how the receptor complex is internalized by the cell, where it is trafficked to, and how these events lead to diverse transcriptional outputs. This system of ligand-receptor inputs leading to diverse outputs is likely dependent on the composition of the receptor complex, and the cellular context of the signal. Deciphering this code will be crucial to our understanding of how cells receive and transduce specific signals. This proposal aims to characterize the communication between trafficking of a specific Wnt signaling receptor complex, and activation of transcription in the nucleus. Although it is known that pairing a Wnt ligand and Frizzled (Fzd) receptor is required for the transduction of many (if not most) Wnt signals, our understanding of the mechanisms through which specific Wnt/Fzd pairings allow the transcriptional activator β-catenin (β-cat) to enter the nucleus is lacking. We have developed a novel system to study specific signal transduction of this nature by fluorescently labeled the Wnt ligand, Fzd receptor, and the transcriptional activator β-cat. This is based on our previous studies which have indicated that there is an exquisitely specific pairing of the ligand Wnt9a with the receptor Frizzled (Fzd)9b, and that specificity of this signal is conferred by the epidermal growth factor receptor (EGFR). This proposal aims to further define the mechanism of Wnt9a/Fzd9b signal transduction by studying the intracellular trafficking of this receptor complex, and coupling this to β-cat movements. By first understanding how one specific Wnt/Fzd pairing establishes a specific signal, we can generate a model for further testing other Wnt/Fzd complexes in different cellular contexts. Furthermore, cell signaling events often cross-over to other pathways; these findings could certainly impact our understanding of how other receptor-ligand complexes lead to diverse outputs in cells. The PI has expertise in Wnt signaling and cell biology, as well as experience with mentoring students to publications in these areas. Successful completion of these projects set the PI and her lab up to be leaders in the field of Wnt signaling, and for long-term success in the field.