Wnt transfer in the intestinal stem cell niche

Wnt 转移至肠道干细胞生态位

• 批准号: 436291821
• 负责人: Dr. Lorenz Mittermeier
• 金额: --
• 依托单位: Duke-NUS Graduate Medical School Singapore
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/436291821?language=en
• 关键词: Wnt; transfer; intestinal; stem; cell

The ongoing regeneration of the intestinal epithelium is critical for human health and a model for understanding the regulation of adult stem cells in their niche. Wnt signaling regulates the proliferation and differentiation of intestinal stem cells (ISCs). Excessive Wnt signaling induces increased stem cell division leading to adenomas and cancer, while the lack of Wnts causes intestinal atrophy. Consequently, Wnt signals are of the utmost importance for the strict regulation of activity and quiescence of ISCs. Recently, several groups independently demonstrated that the Wnts that control the intestinal stem cell niche are made in specialized stromal cells called telocytes. However, despite the importance of Wnts in stem cell regulation, little is known about how these pivotal regulators are delivered from telocytes to the ISCs. It was proposed that long cellular extensions of the telocytes might be essential for Wnt transfer, since they could enable a directed and precise transmission of Wnts to the ISCs. Related structures, called signaling filopodia or cytonemes, are involved in Wnt transport in other tissues. However, the exact mechanisms underlying formation, regulation and movement of telocyte extensions in the intestine are currently unknown. This research project aims to provide deeper insights into the mechanisms involved in the transmission of Wnts from telocytes to ISCs. This work will be performed in the laboratory of Prof. David Virshup at the Duke-NUS Medical School in Singapore, who is an internationally recognized expert in the field of ISC regulation by the Wnt pathway in health and disease. During my two-year postdoctoral fellowship, I will first visualize the Wnt transmitting apparatus of telocytes by high resolution light sheet and electron microscopy enabling 3D reconstruction to gain insight into the nature of the cellular extensions. Second, I will isolate Wnt secreting stromal cells to identify telocyte-enriched genes potentially important for the Wnt secreting apparatus by next generation sequencing. After selection of particular promising screening hits, expression will be validated by in situ hybridization and immunofluorescence microscopy. Finally, I will characterize selected candidate genes in established functional assays measuring transmission of Wnts from telocytes to ISCs. In summary, this project will illuminate the mechanisms by which Wnts are transported from pericryptal, stromal cells to the stem cells in the intestine to regulate proliferation, differentiation and self-renewal. As Wnt signaling is vital in diverse tissues and malfunctions of this system are often accompanied by cancer, this knowledge will have important implications for other organs and might help to develop novel therapeutic approaches to prevent or treat colorectal cancer and other Wnt-addicted diseases in humans.

肠上皮的持续再生对人类健康至关重要，也是了解成体干细胞在其生态位中调控的模型。Wnt信号调节肠干细胞（ISCs）的增殖和分化。过量的Wnt信号传导诱导干细胞分裂增加，导致腺瘤和癌症，而缺乏Wnt会导致肠道萎缩。因此，Wnt信号对于ISCs的活动和静止的严格调节至关重要。最近，几个研究小组独立地证明，控制肠道干细胞生态位的Wnt是在称为端细胞的特化基质细胞中产生的。然而，尽管Wnt在干细胞调控中的重要性，但人们对这些关键调控因子如何从端细胞传递到ISC知之甚少。有人提出，端细胞的长细胞延伸对于Wnt转移可能是必不可少的，因为它们可以使Wnt定向和精确地传输到ISC。相关的结构，称为信号丝状伪足或细胞丝，参与Wnt在其他组织中的转运。然而，端细胞延伸在肠道中的形成、调节和运动的确切机制目前尚不清楚。该研究项目旨在更深入地了解Wnt从端细胞到ISC的传输机制。这项工作将在新加坡杜克-新加坡国立大学医学院的大卫·维尔舒普教授的实验室进行，他是健康和疾病中Wnt途径调控ISC领域的国际公认专家。在我为期两年的博士后研究期间，我将首先通过高分辨率光片和电子显微镜观察端细胞的Wnt传输装置，使3D重建能够深入了解细胞延伸的性质。其次，我将分离Wnt分泌基质细胞，通过下一代测序鉴定对Wnt分泌装置潜在重要的端细胞富集基因。在选择特别有希望的筛选命中后，将通过原位杂交和免疫荧光显微镜验证表达。最后，我将选定的候选基因的特点，在建立的功能测定测量传输的Wnt从端细胞到ISCs。总之，本项目将阐明Wnt从内隐周、基质细胞转运到肠道干细胞以调节增殖、分化和自我更新的机制。由于Wnt信号在不同组织中至关重要，并且该系统的功能障碍通常伴随着癌症，因此这些知识将对其他器官产生重要影响，并可能有助于开发新的治疗方法来预防或治疗结直肠癌和其他Wnt成瘾性疾病。