Strain-Activated Signaling within Cell Adhesions Dictates Cell Fate

细胞粘附中应变激活的信号传导决定细胞的命运

• 批准号: 1463689
• 负责人: Adam Engler
• 金额: $ 40万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-15 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1463689&HistoricalAwards=false
• 关键词: Strain; Activated; Signaling; within; Cell

Just like steel girders hold up buildings, extracellular matrix fibers help hold tissues together. Cells within tissues act like people in buildings: they adhere to and crawl on extracellular matrix like people walk on the floors. Unlike people however, cells also pull against their matrix and can respond to the stiffness of this adjacent matrix. Normally, stem cells respond simply by maturing into the cells already present in the tissue. However diseases often cause these fibers to become stiffer than normal, which makes the stem cells within these tissues respond inappropriately; cells that typically become muscle instead mature into bone. While we have made such observations, our understanding of why this occurs is limited. Thus a systematic examination of how physical cues like stiffness are converted into biochemical cues that a stem cell can interpret is greatly needed. One of the ways that cells can sense the stiffness of the tissues that surround them is through the unfolding of particular molecules from the forces of cellular contraction. Using computer analysis of known protein structures, the investigator has identified two strong candidates for molecules that will unfold and allow the cells to measure force. Cell chemical pathways identified through this study could be targeted in genetic therapies to treat diseases that stiffen tissues such as cancer and heart disease. Cells sense extracellular matrix properties by contracting against it and converting that information into biochemical readouts in a process called mechanotransduction. Despite understanding the inputs and outputs of this process, little is known about mechanically induced signaling that occurs in between these observations. Stem cells are ideally suited to elucidate these molecular details because they present a "blank slate" where maturation into specific tissues can describe the sensitivity of a physical-to-chemical sensor, i.e. fat cells are less contractile than muscle and bone cells. This research will combine current molecular tools and engineering approaches to test whether proteins within a cell adhesion act as a "molecular strain gauge," i.e. it exposes cryptic kinase binding sites under strain. A bioinformatics-based screen has identified 3 proteins with cryptic kinase binding sites, e.g. SORBS1, SORBS3, and vinculin; project objectives will use in situ fluorescence resonance energy transfer assays to describe cellular strain-induced conformational changes in these proteins and validate the "molecular strain gauge" model for signaling. It will also confirm the function of new mechanosensors, which could be used as therapeutic targets to make stem cells insensitive to tissue stiffening.

就像钢梁支撑起建筑物一样，细胞外基质纤维帮助组织结合在一起。组织内的细胞就像建筑物里的人一样：它们附着在细胞外基质上并在上面爬行，就像人们在地板上行走一样。然而，与人不同的是，细胞也会对它们的基质产生拉力，并对相邻基质的硬度做出反应。通常情况下，干细胞的反应仅仅是成熟为组织中已经存在的细胞。然而，疾病经常导致这些纤维变得比正常情况下更硬，这使得这些组织中的干细胞做出不适当的反应；细胞通常会变成肌肉，而不是成熟成骨骼。虽然我们做了这样的观察，但我们对为什么会发生这种情况的理解是有限的。因此，系统地研究诸如硬度之类的物理信号如何转化为干细胞可以解释的生化信号是非常必要的。细胞感知周围组织硬度的一种方式是通过细胞收缩时特定分子的展开。通过对已知蛋白质结构的计算机分析，研究人员已经确定了两个强有力的候选分子，它们将展开并允许细胞测量力。通过这项研究确定的细胞化学途径可能成为基因疗法的目标，以治疗癌症和心脏病等导致组织硬化的疾病。细胞通过收缩细胞外基质的特性，并将信息转化为生化读数，这一过程被称为机械转导。尽管了解这一过程的输入和输出，但对这些观察之间发生的机械诱导信号知之甚少。干细胞是阐明这些分子细节的理想选择，因为它们提供了一块“空白石板”，在那里成熟为特定组织可以描述物理-化学传感器的敏感性，即脂肪细胞比肌肉和骨细胞收缩性更小。这项研究将结合当前的分子工具和工程方法来测试细胞粘附中的蛋白质是否作为“分子应变计”，即它暴露了在应变下的隐激酶结合位点。基于生物信息学的筛选已经确定了3种具有隐激酶结合位点的蛋白质，例如SORBS1， SORBS3和vinculin；项目目标将使用原位荧光共振能量转移分析来描述细胞菌株诱导的这些蛋白质的构象变化，并验证“分子应变计”信号模型。它还将证实新的机械传感器的功能，它可以用作治疗靶点，使干细胞对组织硬化不敏感。