Understanding WNT9A/FZD9 Trafficking and Signaling

细胞间的信号传导是所有多细胞生命的基础。一个细胞分泌的信号分子 能够通过与表面受体的相互作用与其他细胞进行交流， 注意这些信号。一类这样的分泌信号分子由Wnt基因家族编码。 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、组织形成、细胞分裂 极性和干细胞维持。这种多样性的过程发生使用保守的细胞内机制， 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。的至少一部分 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（哺乳动物中有10个）。然而，从关联开始的具体机制 在膜上的各种配体和受体，并导致核转录活性， 不完全理解。这方面的一个缺失环节是破译受体复合物是如何 由细胞内化，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-受体输入系统可能取决于细胞的组成。 受体复合物和信号的细胞背景。破译这段密码对我们理解 细胞是如何接收和处理特定信号的。这项建议旨在说明来文的特点， 在特定Wnt信号传导受体复合物的运输和细胞核中转录的激活之间。 尽管已知Wnt配体和卷曲（Fzd）受体的配对是转导Fzd所需的，但是， 许多（如果不是大多数）Wnt信号，我们对特定Wnt/Fzd配对的机制的理解 允许转录激活因子β-catenin（β-cat）进入细胞核的基因缺乏。我们已经开发出一种新颖 通过荧光标记的Wnt配体，Fzd受体， 和转录激活因子β-cat。这是基于我们以前的研究，这些研究表明 配体Wnt 9a与受体Frizzled（Fzd）9 b的精确特异性配对， 该信号的一部分由表皮生长因子受体（EGFR）赋予。该提案旨在进一步 通过研究Wnt 9a/Fzd 9 b受体的细胞内转运，明确Wnt 9a/Fzd 9 b信号转导机制 复杂，并将其与β-cat运动相结合。通过首先了解一个特定的Wnt/Fzd配对 建立了一个特定的信号，我们可以生成一个模型，用于进一步测试其他Wnt/Fzd复合物在不同的 细胞环境此外，细胞信号传导事件经常交叉到其他途径;这些发现可能 当然会影响我们对其他受体-配体复合物如何导致细胞中不同输出的理解。 PI拥有Wnt信号传导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信号传导领域，并在该领域取得长期成功。

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.