Regulation of nuclear dynamics by tyrosine kinase signaling

每个真核细胞，包括人类细胞，都被分成称为细胞器的隔间。这些细胞器执行特殊的功能，保护细胞免受有害条件的伤害。然而，细胞器的分裂给细胞带来了额外的挑战，特别是在协调细胞活动方面，这些活动决定了特定的细胞行为，如细胞运动和细胞分裂。此外，细胞需要整合来自周围组织微环境的各种信号，并将这些信号传递到所有细胞器。为了通过细胞外和细胞内信号接收和传递指令，细胞拥有复杂的信号电路。这些信号电路由一个蛋白质硬件组成，该硬件通过可逆的蛋白质修饰传递信号，包括蛋白质磷酸化。所有细胞器，包括细胞核，都有自己的信号装置来产生和传播特定的信号。不幸的是，我们对核信号装置的了解在分子和功能层面上仍然有限。为了保持组织的完整性，细胞必须使其行为适应微环境压力，包括拥挤组织中的物理约束。要做到这一点，细胞需要重新排列其细胞核的形状和物理性质。事实上，保护遗传物质的细胞核是最大、最坚硬的细胞器。虽然细胞核形状的动态变化对于决定适当的细胞行为是必不可少的，但它们也会损害遗传物质。因此，核形状的变化对细胞既有好处，也有坏处。其结果是如何在分子水平上确定的，目前尚不清楚。这项研究计划的总体目标是了解细胞如何适应其细胞核的形状和弹性，以应对微环境压力。在接下来的五年里，我们将在分子和功能水平上剖析一种新的信号通路，它可以改变细胞核抵御物理限制的能力。这一途径涉及核蛋白Ash2L被信号通路的关键成分Src磷酸化。利用基因工程细胞模型和创新的生物工程设备，我们将追求两个具体目标：1)通过研究核结构组织、核刚性和核膜修复，描述与Ash2L相关的核弹性机制；2)通过结合活细胞成像和蛋白质修饰的生化分析，评估物理约束对Src-Ash2L途径的调节及其在细胞适应中的作用。这项研究计划将增加我们对细胞和微环境之间的功能关系的理解，这些微环境对组织完整性具有至关重要的影响。它还将产生与生命科学以及分子和细胞工程广泛相关的基础知识。

Each eukaryotic cell, including human cells, is divided into compartments called organelles. These organelles perform specialized functions and protect cells from harmful conditions. However, organelle partitioning presents additional challenges for cells, notably for coordinating cellular activities that dictate specific cell behaviors, such as cell motility and cell division. Moreover, cells need to integrate a variety of signals from the surrounding tissue microenvironment and relay these signals to all organelles. To receive and relay instructions by extra- and intracellular signaling, cells possess sophisticated signaling circuits. These signaling circuits are composed of a protein hardware that conveys signals through reversible protein modifications, including protein phosphorylation. All cellular organelles, including the nucleus, possess their own signaling devices to generate and propagate specific signals. Unfortunately, our understanding of nuclear signaling devices is still limited at both the molecular and functional levels. To maintain tissue integrity, cells must adapt their behaviors to microenvironmental stress including physical constraints in crowded tissues. To achieve this, cells need to rearrange the shape and physical properties of their nucleus. Indeed, the nucleus, which protects genetic material, is the largest and stiffest cell organelle. While dynamic changes in nuclear shape are essential to dictate appropriate cellular behaviors, they can also damage genetic material. Therefore, changes in nuclear shape can either be beneficial or detrimental for cells. How the resulting consequences are determined at the molecular level remains unknown. The general goal of this research program is to understand how cells adapt their nucleus' shape and resilience in response to microenvironmental stress. In the next five years, we will dissect a new signaling pathway that modifies the nucleus' ability to withstand physical constraints, at molecular and functional levels. This pathway involves the phosphorylation of a nuclear protein, Ash2L, by a key component of signaling circuits, Src. Using genetically engineered cell models and innovative bioengineered devices, we will pursue two specific aims: 1) Delineate Ash2L-linked mechanisms of nuclear resilience, by studying nuclear structure organization, nuclear rigidity, and nuclear envelope repair; 2) Assess the regulation of Src-Ash2L pathway by physical constraints and its role in cellular adaptations, by combining live-cell imaging and biochemical analyses of protein modifications. This research program will increase our understanding of functional relationships between cells and the microenvironment that critically impact tissue integrity. It will also generate fundamental knowledge of wide relevance for both life sciences and molecular and cellular engineering.