Differentiation balances oncogene-driven proliferation to maintain epidermal homeostasis

项目摘要 在皮肤上皮细胞中，一群能够明显地增殖、自我更新和 终末分化为有丝分裂后的后代，负责维持整个生命的组织动态平衡。 与增殖和凋亡不同，细胞命运的选择目前是通过定性或间接分析来评估的。 因此，我们缺乏对祖细胞在皮肤过程中如何平衡增殖和分化的充分了解 发育和动态平衡，或皮肤的生长障碍。 我们的长期目标是建立表皮祖细胞如何在存在的情况下平衡生长 致癌基因突变以维持组织动态平衡。为了做到这一点，我们开发了一种新的方法来直接定量 动态期和增殖期表皮祖细胞自我更新和分化的速率 成长。我们将在小鼠模型中应用我们的检测方法，以表达生理水平的 皮肤中具有结构性活性的HRAs和PIK3CA。此外，我们将使用我们最近开发的快速基因- 靶向方法，探索Ras-PI3K信号的特异性效应子和底物如何修饰表皮 体内分化。 本应用程序旨在验证以下假设：1.)分化程度增加可以平衡有丝分裂 致癌信号在维持组织动态平衡中的作用；RAS效应器PIK3CA启动一种分子 包括Akt和特定Akt底物的级联，以调节 皮肤表皮；3)表皮祖细胞对癌基因表达的反应是异质性的 受祖细胞生态位的影响。 我们的研究结果有望立即揭示细胞和分子原理 尽管有大量促进生长的突变，但仍能保持皮肤的动态平衡和功能。这些 这些发现将是开发操纵祖细胞的药理学策略的关键一步。 表皮中的潜力，用于治疗以组织生长不受限制为标志的疾病。

Project Summary In skin epithelium, a population of progenitor cells distinctly capable of proliferation, self-renewal, and terminal differentiation into post-mitotic progeny, is responsible to sustain tissue homeostasis throughout life. Unlike proliferation and apoptosis, cell fate choices are currently assessed using qualitative or indirect assays. As a result, we lack full understanding of how progenitors balance proliferation with differentiation during skin development and homeostasis, or in growth disorders of the skin. Our long-term objective is to establish how epidermal progenitor cells balance growth in the presence of oncogenic mutations to maintain tissue homeostasis. To do so, we developed a novel assay to directly quantify rates of progenitor cell self-renewal and differentiation in epidermis during homeostatic and hyperproliferative growth. We will employ our assay in the mouse models engineered to express physiological levels of constitutively active Hras and Pik3ca in the skin. In addition, we will use our recently developed rapid gene- targeting method, to explore how specific effectors and substrates of RAS-PI3K signaling modify epidermal differentiation in vivo. This application aims to test the hypotheses that: 1.) Increased differentiation can balance mitogenic effects of oncogenic signaling to maintain tissue homeostasis; 2.) Ras effector Pik3ca initiates a molecular cascade that includes Akt and specific Akt substrates to regulate progenitor cell renewal and differentiation in skin epidermis; and 3.) Epidermal progenitor response to oncogene expression is heterogeneous and influenced by progenitor cell niche. The results of our research are expected to immediately uncover cellular and molecular principles that maintain skin homeostasis and functionality despite the abundance of growth-promoting mutations. These findings will be a critical step in development of pharmacological strategies to manipulate progenitor cell potential in the epidermis, to treat conditions marked by unrestrained tissue growth.