Regulation of self-renewal of pluripotent stem cells by integrin signaling

干细胞是具有独特能力的细胞，可以分裂为相同的子细胞或分化为专门的细胞类型。对干细胞生物学的更好理解将促进对器官和组织在生物体生命过程中如何形成和维持的知识，因为干细胞负责这些功能。特别是，该项目将阐明阻止多能干细胞分化的信号通路的三个不同组成部分的作用，这转化为干细胞在个体生命周期中如何维持。此外，它还将为直接参与该项目研究活动的两名研究生和多名本科生提供培训机会。此外，数十名研究生将接受有效地向公众传播科学知识的方法的培训。首席研究员的长期目标是阐明调控干细胞静止、自我更新和分化的分子信号机制，以及它们与它们所处的微环境的联系。在这个项目中，研究人员将确定跨膜蛋白整合素α6的特定剪接异构体在其异二聚体整合素β1失活中的作用，这将导致维持多能干细胞自我更新的信号。为此，研究人员将使用包含特定剪接异构体的干细胞群体的细胞分类及其基因操作来确定它们的分子调控。此外，还将确定参与整合素信号转导的两种蛋白激酶：粘着斑激酶(FAK)和整合素连接激酶(ILK)的分子功能。这两个激酶作为支架蛋白发挥关键作用，促进与细胞谱系决定相关的转录因子的降解，从而维持多能干细胞的自我更新，这一假说将得到验证。为此，研究人员将通过免疫沉淀分析和这些相互作用的化学/遗传操作来验证这些支架蛋白与特定泛素酶蛋白和靶向转录因子的络合作用。这些实验的潜在发现可能具有重大意义，因为它们可以更好地理解整合素信号通路如何调节干细胞及其微环境之间的相互联系。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Stem cells are cells with the unique ability to divide into identical daughter cells or to differentiate into specialized cell types. A better understanding of stem cell biology will advance knowledge of how organs and tissues are formed and maintained during the life of an organism, as stem cells are responsible for those functions. In particular, this project will elucidate the role of three different components of a signaling pathway preventing the differentiation of pluripotent stem cells, which translates into how stem cells are maintained during an individual’s life span. In addition, it will provide training opportunities for two graduate students and multiple undergraduates, who will be directly involved in the research activities of this project. Furthermore, dozens of graduate students will be trained in methods to effectively communicate scientific knowledge to the public.The long-term goal of the principal investigator is to elucidate the molecular signaling mechanisms regulating quiescence, self-renewal, and differentiation of stem cells and their connection with the microenvironment in which they reside. In this project, the investigators will determine the role of specific spliced isoforms of the transmembrane protein integrin alpha6 in the inactivation of its heterodimer partner integrin beta1, which results in signaling that sustains self-renewal of pluripotent stem cells. For this, the investigators will use cell-sorting of stem cell populations containing the specific spliced isoform and their genetic manipulation to determine their molecular regulation. In addition, the molecular function of two protein kinases involved in integrin signaling: Focal Adhesion Kinase (FAK) and Integrin-Linked Kinase (ILK), will be determined. The hypothesis that both kinases play key roles as scaffold proteins promoting the degradation of transcription factors related to cell lineage determination, and therefore sustaining self-renewal of pluripotent stem cells, will be tested. For this, the investigators will verify the complexation of these scaffold proteins with specific ubiquitinase proteins and targeted transcription factors by immunoprecipitation assays, and chemical/genetic manipulations of these interactions. The potential findings from these experiments may have significant implications as they could provide a better understanding of how integrin signaling pathways mediate the interconnection between stem cells and their microenvironment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.