Force Sensing with Nanotubes

描述（由申请方提供）：大多数人类恶性肿瘤是上皮来源的。转化的上皮细胞从原发肿瘤部位扩散并通过产生迁移结构（例如，丝状伪足、内陷伪足和板状伪足）。迁移结构的相对丰度与肿瘤细胞的转移潜力相关。迁移结构通过在转化的上皮细胞的前缘重塑肌动蛋白而形成。生长因子（例如，表皮生长因子，EGF）通过靶向它们的受体（例如，表皮生长因子受体）。虽然表皮生长因子途径是很好的特点，我们缺乏实验证据来量化的力量，有助于迁移，包括粘附牵引力，粘性阻力，和膨胀力。这项工作将集中在一个活细胞的前沿发生的冲击力。当肌动蛋白聚合时释放的化学能产生对质膜的推力时，它们就会出现，这是由溶液中单体肌动蛋白相对于生物聚合物的浓度更高所驱动的。当肌动蛋白束附着在质膜上时，F-肌动蛋白的解聚在膜上产生拉力。这种逆化学反应是由本体中相对于生物聚合物较低浓度的单体驱动的。缺乏对活细胞中推力的大小和时间过程的实验测量，也没有对F-肌动蛋白解聚产生的拉力的测量。这项工作的目标是确定的时间过程和大小的推动力和拉力的快速增长结束的F-肌动蛋白束。我们将使用膜作为传感器来确定癌细胞中运动水平的力。我们将通过EGF或EGF途径中的活性效应物刺激转化的上皮细胞形成迁移结构。我们将使用光镊来测量力，荧光显微镜来成像F-肌动蛋白，并开发同时测量两者的方法。这项工作将提供一个功能模型的肌动蛋白电机在转化的上皮细胞的前沿，并推进该领域的理解细胞迁移在癌症的侵袭性阶段，通过提供测量的压力在一个前沿。这将提供一个定量的实验方法来研究这种化学马达的转导机制，并从根本上了解细胞膜和肌动蛋白马达的整合运作。这项工作将为设计纳米技术应用的力传感器提供基础。 公共卫生相关性：这项研究将帮助我们更好地了解F-肌动蛋白的具体作用，F-肌动蛋白是所有哺乳动物细胞中的关键蛋白质。这种蛋白质在细胞生长和发育中起着重要作用。它在许多侵袭性癌症的侵袭阶段具有重要作用。该研究技术将推动生物分子传感器在纳米技术中的应用。

DESCRIPTION (provided by applicant): Most human malignancies are of epithelial origin. Transformed epithelial cells spread from the primary tumor site and invade surrounding tissues through the production of migratory structures (e.g., filopodia, invadopodia, and lamellapodia). The relative abundance of migratory structures is correlated with the metastatic potential of tumor cells. Migratory structures form by remodeling actin at the leading edge of transformed epithelial cells. Growth factors (e.g., epidermal growth factor, EGF) initiate actin remodeling by targeting their receptors (e.g., epidermal growth factor receptor) on the plasma membrane of transformed cells. Although the EGF pathway is well characterized, we lack experimental evidence to quantify forces that contribute to migration, including adhesive traction, resistive viscous drag, and protrusive forces. This work will focus on protrusive forces that occur at the leading edge of a living cell. They arise when the chemical energy released upon actin polymerization produces a pushing force against the plasma membrane, driven by the greater concentration of monomeric actin in the solution relative to the biopolymer. When an actin bundle is attached to the plasma membrane, depolymerization of F-actin produces a pulling force on the membrane. This reverse chemical reaction is driven by a lower concentration of monomer in the bulk relative to the biopolymer. Experimental measurements of the magnitude and time course of the pushing force in living cells are lacking and there are no measurements of the pulling force arising from the depolymerization of F-actin. The goal of this work is to determine the time course and magnitude of the pushing and pulling forces at the fast-growing end of an F-actin bundle. We will use the membrane as a sensor to determine the force at the motor-level in cancer cells. We will stimulate transformed epithelial cells to form migratory structures by EGF or with active effectors within the EGF pathway. We will use optical tweezers to measure the force, fluorescence microscopy to image F- actin, and develop methodology to measure both simultaneously. This work will provide a functional model of the actin motor at a leading edge of transformed epithelial cells, and advance the field in understanding cell migration during the invasive stage of cancer by providing measurements of the protrusive force at one leading edge. It will provide a quantitative experimental method to investigate the transduction machinery of this chemical motor, and fundamental insight into the integrated operations of the cell membrane and actin motor. This work will provide a basis to design force sensors for applications in nanotechnology. PUBLIC HEALTH RELEVANCE: This study will help us to better understand specific roles of F-actin, a key protein in all mammalian cells. This protein plays an important role in cell growth and development. It has a significant role during the invasive stage of many aggressive cancers. The research techniques will advance the development of bio-molecular sensors for applications in nanotechnology.