Regulation of Quiescence and Activation in Skin Stem Cells

描述(由申请人提供)：这项建议的长期目标是了解干细胞的活性如何被适当地调节以维持体内平衡和组织完整性。毛囊是皮肤的重要附属物之一，是解决这一问题的理想范例。毛囊经历了生长(生长期)、破坏(退化期)和休止期(休止期)。毛囊干细胞(HfSCs)位于毛囊的永久性突起中，这种结构被称为凸起。在隆起周期中的hfSCs很少出现。在正常的动态平衡期间，hfSCs只在生长期的一个非常短暂的时间段内增殖，而在所有其他阶段保持静止。在受伤时，高频干细胞也会被激活。对HFSC活性的违反将导致严重的后果。例如，脱发(脱发)和伤口愈合延迟可能是由于hfSCs激活效率低下所致。相反，皮肤肿瘤，如基底细胞癌和鳞状细胞癌，可以源于HFSC的过度增殖。干细胞的活动很大程度上受到其微环境的影响，这种微环境被称为利基。传统上，关于生态位的研究只关注周围的异源细胞类型，即来自不同谱系的细胞。包括我自己在内的最近的研究发现，干细胞后代在几个脊椎动物和无脊椎动物干细胞系统中作为利基成分的重要性，这在以前是没有被认识到的。在毛囊中，我的初步研究发现有两个重要的后代群体是关键的 HFSC扩散的监管机构。这一提议要检验的中心假设是，来自HFSC后代的反馈调节对于hfSCs的正确行为和活动至关重要。这一假说将通过以下实验来验证：1)检测子代表达的候选信号；2)确定子代在生理和病理条件下对HFSC激活的贡献；3)确定子代表达的调节hfSCs的新功能因子。候选信号将在指导阶段进行调查。后代在动态条件下的贡献以及后代所表达的已确定的新因素将在独立阶段得到跟踪。这些实验的成功完成将极大地促进我们对调控HFSC增殖和静止的细胞类型和信号的理解。此外，这些拟议的研究可能会导致与干细胞活性异常相关的皮肤病的治疗方法的开发。我的长期职业目标是领导一个成功的、独立的、资金充足的实验室，研究皮肤和干细胞生物学。到目前为止，我的研究生和博士后培训使我在技术和智力上都为开发严谨的研究项目做好了准备。这个职业发展奖和我提出的研究计划将进一步为我提供机会，扩大我在皮肤干细胞生物学和小鼠遗传学方面的知识，获得生物信息学分析、小鼠胚胎操作、基于图像的FACS分析方面的新技能，并进一步积累经验，以提高指导、演示和写作技能，所有这些都是我作为一名独立研究人员未来成功的关键。在指导阶段产生的试剂也将帮助我在独立阶段建立研究计划。洛克菲勒大学及其邻近的两所机构，纪念斯隆-凯特琳癌症中心和威尔·康奈尔医学院，提供了一流的研究环境和许多研讨会和课程，以支持我提议的研究和我的职业发展。我将与我的导师Elaine Fuchs博士、我的合作者Olivier Elemento博士以及纽约地区的皮肤和老鼠发育生物学社区保持持续的互动。他们将一起评估我的进步，并提出批评或建议。总之，拟议的学习和职业发展计划将为我的独立科学生涯做好更好的准备，确保我实现我的长期职业目标，并使我能够为我们理解干细胞活动如何在动态平衡和疾病中调节做出持续的贡献。

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to understand how the activity of stem cells is properly regulated to maintain homeostasis and tissue integrity. The hair follicle, one of the important skin appendages, is an ideal paradigm to address this problem. Hair follicles undergo cycles of growth (anagen), destruction (catagen) and rest (telogen) phases. Hair follicle stem cells (HFSCs) are located in a permanent protrusion of the hair follicle, a structure known as the bulge. HFSCs in the bulge cycle infrequently. During normal homeostasis, HFSCs only proliferate in a very transient window of anagen, while remaining quiescent during all the other phases. HFSCs can also become activated upon wounding. Dis-regulation of HFSC activity results in severe consequences. For example, alopecia (hair loss) and delayed wound healing may arise from inefficient activation of HFSCs. On the contrary, skin tumors, such as basal cell carcinoma and squamous cell carcinoma, can derive from HFSC hyper-proliferation. Stem cell activity is heavily influenced by their microenvironment, known as the niche. Traditionally, studies about niche focus only on the surrounding heterologous cell types, i.e., cells originated from a different lineage. Recent studies including my own discover the importance of stem cell progeny as niche components in several vertebrate and invertebrate stem cell systems, which is previously unrecognized. In the hair follicle, my preliminary studies have identified two important progeny populations as critical regulators for HFSC proliferation. The central hypothesis to be tested by this proposal is that feedback regulation from HFSC progeny is crucial for the proper behavior and activity of HFSCs. This hypothesis will be tested in this grant application by experiments that: 1) examine candidate signals expressed by the progeny 2) determine the contributions of the progeny to HFSC activation under physiological and pathological conditions and 3) identify novel functional factors expressed by the progeny to regulate HFSCs. Candidate signals will be investigated during the mentored phase. The contributions of progeny under dynamic conditions as well as identified novel factors expressed by the progeny will be follow-up during the independent phase. Successful completion of the proposed experiments will significantly advance our understanding of the cell types and signals that regulate HFSC proliferation and quiescence. In addition, these proposed studies will potentially lead to the development of therapeutic treatments for skin disorders associate with aberrant stem cell activity. My long-term career goal is to lead a successful, independent, and well-funded laboratory studying skin and stem cell biology. My graduate and postdoctoral training up to date has prepared me technically and intellectually to develop rigorous research projects. This career development award and my proposed research plan will further provide me with opportunities to expand my knowledge in skin stem cell biology and mouse genetics, gain new skills in bioinformatics analysis, mouse embryo manipulation, image-based FACS analysis, and further accumulate experience to improve mentoring, presentation, and writing skills, all of which are critical to my fuure success as an independent researcher. The reagents generated during the mentored phase will also help to build up my research program in the independent phase. The Rockefeller University together with its two neighboring institutions, Memorial Sloan-Kettering Cancer Center and Weill Cornell Medical College, offer a prime research environment and many workshops and courses to support my proposed research and my career development. I will have constant interactions with my mentor Dr. Elaine Fuchs, my collaborator Dr. Olivier Elemento, and the skin and mouse developmental biology communities in the New York area. Together they will assess my progress and provide critique or advice. In summary, the proposed studies and career development plan will better prepare me for my independent scientific career, ensure that I achieve my long-term career goals, and allow me to make continuous contributions towards our understanding of how stem cell activity is regulated in homeostasis and disease.