RUI: The role of mitotic trafficking in cell fate specification

在发育中的胚胎中，细胞形成的组织类型主要取决于每个细胞从邻近细胞接收到的信号。这些相同的信号也调节成年组织中功能齐全的细胞的行为。细胞信号的缺陷是许多出生缺陷的原因，也可能导致癌细胞的形成。尽管在理解细胞信号传导的分子基础方面已经取得了巨大的进步，但大部分工作都是在不分裂的细胞中进行的。细胞分裂对细胞对信号的反应的影响仍然知之甚少。这个项目将通过检查细胞分裂和信号传导之间的相互作用来帮助填补这一关键的空白。拟议中的实验将研究从邻近细胞接收信号的蛋白质如何在分裂的细胞内移动。由于癌细胞和胚胎细胞都频繁分裂，这些信号受体蛋白在细胞分裂过程中的分布可能在形成胚胎细胞身份和促进癌细胞行为方面发挥关键作用。该提案还将促进对设计和实施独立研究项目的各类本科研究人员的强化培训。该项目还将通过与费城地区许多成熟的外展项目的互动来促进公共教育。技术段：细胞命运诱导受信号成分传输的影响。最近的研究推翻了长期以来的假设，即膜运输在有丝分裂期间被关闭。因此，信号成分的有丝分裂运输可能在细胞命运规范中发挥着深刻的，很大程度上未被认识的作用。PI的长期目标是了解细胞分裂如何影响感应信号处理。这个问题是通过检查心脏祖细胞诱导的基础脊索动物，小肠。PI利用了Ciona胚胎的极端细胞简单性，对诱导信号机制进行了高分辨率的体内分析，并专注于成纤维细胞生长因子（FGF）依赖的心脏祖细胞谱系诱导。研究发现，FGF受体（FGFRs）的有丝分裂再分配促进了差异心脏祖细胞的诱导。PI假设有丝分裂激酶调节富含fgfr的粘附结构域的运输，并将通过以下具体目的来验证这一假设：1)通过对活的完整胚胎中标记蛋白的图像分析来表征富含fgfr的信号结构域的有丝分裂运输；2)通过使用通路特异性标记物和靶向破坏通路特异性组分的共定位分析，描绘特异性内吞通路在信号域重新分配中的作用；3)确定有丝分裂激酶如何通过靶向破坏激酶活性影响fgfr富集结构域的内吞运输。这些研究的完成将为胚胎和干细胞分裂和信号传导之间的相互作用提供基本的见解。

Non-Technical Paragraph:In developing embryos, the type of tissue that a cell becomes is primarily determined by signals each cell receives from its neighbors. These same signals also regulate the behavior of fully functional cells in adult tissues. Defects in cell signaling are the cause of many birth defects and can also cause cancer cells to form. Although great strides have been made in understanding the molecular basis of cell signaling, most of this work has been conducted in cells that are not dividing. The effect of cell division on cell response to signals remains poorly understood. This project will help fill this crucial gap by examining the interplay between cell division and signaling. The proposed experiments will examine how proteins that receive signals from neighboring cells are moved around inside dividing cells. Because both cancer cells and embryonic cells frequently divide, the distribution of these signal-receiver proteins during cell division is likely to play a crucial role in creating embryonic cell identity and in promoting cancerous cell behaviors. This proposal will also promote intensive training of diverse undergraduate researchers in designing and carrying out independent research projects. The project will also promote public education through interactions with many well-established outreach programs in the Philadelphia area.Technical Paragraph:Cell fate induction is affected by trafficking of signal components. Recent studies have overturned the long-held assumption that membrane trafficking is shut down during mitosis. Thus, mitotic trafficking of signaling components may play a profound, largely unrecognized role in cell fate specification. The long-term goal of the PI is to understand how cell division affects inductive signal processing. This question is addressed by examining heart progenitor induction in the basal chordate, Ciona intestinalis. The PI has exploited the extreme cellular simplicity of Ciona embryos to perform high-resolution, in vivo analysis of inductive signaling mechanisms, and focuses on Fibroblast Growth Factor (FGF)-dependent induction of the heart progenitor lineage. Mitotic redistribution of FGF receptors (FGFRs) was found to promote differential heart progenitor induction. The PI hypothesizes that mitotic kinases regulate trafficking of FGFR-enriched adherent domains, and will test this hypothesis through the following specific aims: 1) Characterization of mitotic trafficking of FGFR-enriched signaling domains through image analysis of tagged proteins in live, intact embryos; 2) Delineation of the role of specific endocytic pathways in signaling domain redistribution through co-localization analysis using pathway-specific markers and targeted disruption of pathway-specific components; 3) Determination of how mitotic kinases affect endocytic trafficking of FGFR-enriched domains through targeted disruption of kinase activity. Completion of the proposed studies will provide fundamental insights regarding the interplay between division and signaling in both embryonic and stem cells.