Cell junction and nuclear forces as mediators of epithelial cell homeostasis

上皮细胞排列在体腔内外，以单层存在于组织中， 多层细胞和三维管/导管结构。正常形成和体内平衡 上皮细胞对于组织和器官功能至关重要;上皮细胞的失调与上皮细胞的增殖有关。 屏障丧失（包括脓毒症）、伤口愈合缺陷以及癌症的发展和进展。虽然 上皮细胞上的机械力已显示影响细胞组织、增殖和 迁移，细胞对力的反应机制尚不清楚。本提案审查了以下方面的作用： 在细胞-细胞连接和核骨架与细胞骨架的核连接体（LINC）中跨蛋白质的力 作为上皮稳态的介质。强的细胞-细胞连接对于细胞的完整性至关重要。 上皮，包括细胞凝聚力，屏障功能和抵抗机械应力的能力。失去连接是 与上皮功能障碍相关，包括炎症诱导的渗透性和上皮细胞 间充质转化（EMT）。虽然形成细胞间粘附已被证明是至关重要的 调节细胞增殖，迁移和组织组织，很少有人知道细胞间连接是如何发生的。 这些力量促成了这些过程。除了改变连接力外，外部施加的力也可能 在细胞内通过细胞骨架传递到细胞器上。原子核，在物理上 通过LINC复合物连接到细胞骨架的细胞可能受到外力的影响。核力量 有人建议调节核的几何形状和核的位置，这两者在各种不同的情况下都发生了改变。 疾病，包括癌症。本MIRA建议的主要研究目标是研究如何跨部队 细胞-细胞连接蛋白和核LINC复合物调节上皮细胞增殖、迁移、连接 稳定性和3D组织。基于FRET的新型张力生物传感器将用于直接测量力 穿过紧密连接、粘附连接和细胞-细胞连接处的桥粒， 在LINC复合体的Nesprin。对于接合或核力被扰动的处理或突变体， 用于评估力在上皮调节中的因果性质。本提案的另一个目标是 确定细胞-细胞连接、细胞-基质粘附和细胞核之间的力之间的关系， LINC复合体，识别力如何从细胞的一个区域传递到另一个区域。这 对细胞-细胞、细胞-基质和核力的全面研究将大大促进对 上皮稳态，包括伤口修复、炎症和上皮组织的过程 发展和组织，以及上皮疾病，包括癌症，纤维化，和慢性 炎症结力和核力可能代表了一种调节扩散的普遍机制， 移民和组织;因此，这项研究的结果也可能与大量的非- 上皮细胞和组织。

Epithelial cells, which line both the inside cavities and outside of the body, exist in tissues as monolayers, multilayers of cells, and three dimensional tube/duct structures. Proper formation and homeostasis of the epithelium is critical for tissue and organ function; dysregulation of the epithelium is associated with epithelial barrier loss (including sepsis), defective wound healing, and development and progression of cancer. Although mechanical forces on epithelial cells have been shown to influence cell organization, proliferation, and migration, it is not known the mechanisms by which cells respond to force. This proposal examines the role of force across proteins in both cell-cell junctions and the nuclear linker of nucleoskeleton to cytoskeleton (LINC) complex as mediators of epithelial homeostasis. Strong cell-cell junctions are critical to the integrity of the epithelium, including cell cohesion, barrier function, and ability to resist mechanical stress. Loss of junctions is associated with epithelial dysfunction including inflammatory-induced increases in permeability and epithelial to mesenchymal transition (EMT). Although formation cell-cell adhesions have been shown to be critical regulators of cell proliferation, migration, and tissue organization, very little is known how cell-cell junction forces contribute to these processes. In addition to altering junction forces, externally applied forces are likely transmitted inside the cell, across the cytoskeleton, and onto organelles. The nucleus, which is physically connected to the cytoskeleton by the LINC complex, is likely affected by external forces. Nuclear forces have been suggested to regulate nuclear geometry and nuclear positioning, both of which are altered in a variety of diseases, including cancer. The major research goals of this MIRA proposal are to examine how forces across cell-cell junction proteins and the nuclear LINC complex regulate epithelial proliferation, migration, junction stability, and 3D organization. Novel FRET-based tension biosensors will be used to directly measure forces across tight junctions, adherens junctions, and desmosomes at cell-cell junctions and specific isoforms of nesprin at the LINC complex. Treatments or mutants for which junction or nuclear force is perturbed will be used to assess the causal nature of force in regulation of the epithelium. An additional goal of this proposal is to identify the relationship between forces across cell-cell junctions, cell-matrix adhesions, and the nuclear LINC complex, identifying how forces are transmitted from one region of the cell to another. This comprehensive study of cell-cell, cell-matrix, and nuclear forces will greatly advance the understanding of epithelial homeostasis, which includes the processes of wound repair, inflammation, and epithelial tissue development and organization, as well as epithelial diseases, including cancer, fibrosis, and chronic inflammation. Junction and nuclear forces may represent a universal mechanism to regulate proliferation, migration, and organization; therefore, results from this study may also be relevant to a large number of non- epithelial cells and tissues.