Toward understanding the molecular mechanisms of Merkel cell fate determination

理解默克尔细胞命运决定的分子机制

• 批准号: 9980314
• 负责人: Elena Ezhkova
• 金额: $ 36.98万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-10 至 2022-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9980314
• 关键词: ATAC-seq; Ablation; Adaptor Signaling Protein; Address; Adult; Afferent Neurons; Alleles; Animals; Appearance; Behavioral; Binding; Binding Sites; Biological Assay; Biology; Cell Lineage; Cell physiology; Cells; Chromatin; Complex; Coupled; Critical Pathways; DNA; DNA Binding; DNA Sequence Alteration; Data; Development; Disease; Dorsal; Embryo; Epidermis; Epithelial; Epithelium; Esthesia; Exhibits; Fibroblast Growth Factor; Fibroblast Growth Factor Receptor 2; Fire - disasters; Gene Expression; Gene Expression Profiling; Genes; Genetic Transcription; Hair; Hair follicle structure; Health; Homeostasis; Image; Injections; Knowledge; Lead; Light; Maintenance; Mechanoreceptors; Mediating; Merkel Cells; Merkel cell carcinoma; Molecular; Morphogenesis; Multipotent Stem Cells; Mus; Mutant Strains Mice; Mutation; Neurites; Neurons; Organ; Perception; Population; Process; Proteins; RNA Interference; Role; Sensory; Series; Shapes; Signal Pathway; Signal Transduction; Skin; Specific qualifier value; Structure; Subfamily lentivirinae; Surface; System; Tactile; Temperature Sense; Testing; Texture; Touch sensation; Transcription Process; blastomere structure; conditional knockout; effective therapy; experimental study; in utero; in vivo; loss of function; multipotent cell; mutant; novel; pain sensation; prevent; recruit; response; skin disorder; stem cells; transcription factor; transcriptome sequencing

Summary The skin epithelium provides essential protective and sensory functions for the body. It consists of the epidermis, which serves as a barrier, the hair follicles, which are important for thermal protection, and the Merkel cells, which are innervated mechanosensory cells that mediate light touch sensations for texture and shape recognition. While the development and homeostasis of the epidermis and hair follicles have been well studied, the biology of the Merkel cells is not as well understood. Much of our knowledge on the mechanisms controlling Merkel cells comes from the analysis of murine dorsal skin, in which Merkel cells are organized in crescent-shaped structures called touch domes, and are located around primary hair follicles. Our recent studies revealed close relationship between hair follicle and Merkel cell development, as genetic mutations that abrogate early stages of hair formation in the mouse also result in the loss of Merkel cells. We further investigated this phenomenon and, by performing lineage tracing experiments, we showed that Sox9+ embryonic hair follicle stem cells, which are known to give rise to the hair follicles and adult hair follicle stem cells, also give rise to Merkel cells. We also dissected the mechanisms controlling the specification of Sox9+ cells to the Merkel cell lineage and showed the importance of fibroblast growth factor (Fgf) signaling in this process. Indeed, we found that epidermal loss of Fgf receptor 2 (FgfR2) prior to hair morphogenesis does not affect the appearance of Sox9+ cells or the development of the hair follicles, but leads to loss of Merkel cells. Taken together, we hypothesize that Sox9+ cells are embryonic multipotent stem cells that give rise to both the hair follicle and Merkel cell lineages, and FgfR2-mediated signaling functions to promote the differentiation of Sox9+ cells into Merkel cells. This competitive renewal will focus on testing the above hypothesis. In Aim 1, we will test the significance of Sox9+ cells for Merkel cell formation. We will perform in vivo lineage tracing and ex vivo live imaging assays to confirm that Sox9+ cells are Merkel cell precursors. We will also perform conditional ablation of the transcription factor Sox9, which is known to be essential for the maintenance of Sox9+ embryonic hair follicle stem cells, and analyze the effect on Merkel cell formation. In Aim 2, we will investigate the molecular mechanisms of FgfR2-mediated control of Merkel cell development. We will identify FgfR2-mediated intracellular signaling pathways that are critical for Merkel cell formation by analyzing an allelic series of conditional mouse mutants of fgfr2 that prevent the binding of effector proteins. We will next select candidate transcriptional factors that execute Fgfr2 transcriptional responses and test their significance for Merkel cell formation. In summary, these studies will define the dynamic interplay between signaling and transcriptional processes in the control of Merkel cell fate determination.

概括 皮肤上皮为身体提供必要的保护和感觉功能。它由 表皮，作为屏障，毛囊，对于热保护很重要，以及 默克尔细胞是受神经支配的机械感觉细胞，介导对纹理和纹理的轻触感觉 形状识别。虽然表皮和毛囊的发育和稳态保持良好 研究表明，默克尔细胞的生物学特性尚不清楚。 我们关于控制默克尔细胞机制的大部分知识都来自对小鼠的分析 背侧皮肤，其中默克尔细胞组织成新月形结构，称为触摸圆顶，并且 位于初级毛囊周围。我们最近的研究揭示了毛囊与毛囊之间的密切关系 默克尔细胞发育，因为基因突变会破坏小鼠毛发形成的早期阶段 导致默克尔细胞丧失。我们进一步研究了这一现象，并通过进行谱系追踪 实验中，我们发现 Sox9+ 胚胎毛囊干细胞，已知它们可以产生头发 毛囊和成人毛囊干细胞也会产生默克尔细胞。我们还剖析了机制 控制 Sox9+ 细胞对 Merkel 细胞谱系的规范，并显示成纤维细胞的重要性 在此过程中生长因子（Fgf）信号传导。事实上，我们发现表皮 Fgf 受体 2 (FgfR2) 缺失 在头发形态发生之前不影响 Sox9+ 细胞的外观或头发的发育 毛囊，但会导致默克尔细胞的损失。综上所述，我们假设 Sox9+ 细胞是胚胎细胞 产生毛囊和默克尔细胞谱系的多能干细胞，以及 FgfR2 介导的 信号传导功能促进Sox9+细胞分化为Merkel细胞。 本次竞争性更新将重点测试上述假设。在目标 1 中，我们将测试显着性 用于默克尔细胞形成的 Sox9+ 细胞。我们将进行体内谱系追踪和离体活体成像测定 确认Sox9+细胞是默克尔细胞前体。我们还将进行有条件的消融 转录因子 Sox9，已知对于维持 Sox9+ 胚胎毛囊至关重要 干细胞，并分析对默克尔细胞形成的影响。在目标 2 中，我们将研究分子 FgfR2介导的默克尔细胞发育控制机制。我们将鉴定 FgfR2 介导的 通过分析一系列等位基因，研究对默克尔细胞形成至关重要的细胞内信号通路 fgfr2 的条件性小鼠突变体可阻止效应蛋白的结合。我们接下来将选择候选人 执行 Fgfr2 转录反应并测试其对默克尔细胞意义的转录因子 形成。总之，这些研究将定义信号传导和转录之间的动态相互作用 控制默克尔细胞命运决定的过程。