Cell and mechanobiology of Asymmetric Cell Division

项目摘要 产生具有不同命运、功能和行为的细胞对于细胞的发育和生长至关重要。 维持组织、器官和多细胞生物。蜂窝多样性可以通过以下方式产生： 不对称细胞分裂（ACD）。干细胞利用ACD产生分化的同胞细胞， 在这个过程中维持干细胞。除了蛋白质或RNA的不对称分配之外， 诸如机械线索、同胞细胞大小不对称或细胞器不对称等机制可能 也可能有助于决定二元细胞的命运。 在这里，我建议使用不对称分裂的果蝇成神经细胞，即神经干细胞。 建立果蝇中枢神经系统模型，研究ACD的细胞学和力学生物学。最近， 我们发现，非肌肉肌球蛋白II依赖性皮质流，通过极性和 纺锤体依赖的线索，涉及产生的同胞细胞大小不对称。我会调查 诱导皮质流并以时空精确度进行调制，以获得可再现的同胞细胞 大小不对称。我们最近发现蛋白激酶N（PKN）和Rho GT3途径作为诱导剂 会提供分子进入点我还将研究细胞大小的不对称如何影响 细胞命运的决定，使用RNA测序，免疫组织化学，和长期活细胞成像在体内。 该研究方向包含的第二个项目旨在研究 分子中心体不对称性的机制和功能，这表现在偏向微管 组织中心（MTOC）活动在间期。我们发现了新的蛋白质和机制，如 有丝分裂中驱动蛋白、Pp 4和动态中心粒蛋白定位，调节中心体不对称性。 中心体分离在干细胞中是高度定型的，但中心体是否以及如何分离是一个问题。 不对称性影响细胞命运决定，仍有待解决。我们将用果蝇的神经干细胞 探讨ACD过程中中心体不对称的机制和功能。我特别感兴趣 在研究中心体不对称是否提供了偏向细胞命运决定因素的机制时 分离，无论是通过不对称RNA或姐妹染色单体分离。我也会调查是否有偏见 MTOC活性通过染色质组织影响转录调控。 这项研究计划将受益于几种新颖和创新的工具，包括活细胞成像， 超分辨率显微镜、RNA测序和急性蛋白质错误定位和扰动系统 （纳米抗体，光遗传学），我的实验室实施了探测细胞骨架动态与高空间和/或 体内时间精度。 ACD是一种进化保守的机制，提出的研究计划是医学上的 这是因为ACD的缺陷可能导致神经发育障碍或癌症。

PROJECT SUMMARY Generating cells with different fates, functions and behaviors is critically important for the development and maintenance of tissues, organs, and multicellular organisms. Cellular diversity can be generated through Asymmetric Cell Division (ACD). Stem cells utilize ACD to create differentiating sibling cells while maintaining the stem cell in the process. In addition to the asymmetric partitioning of proteins or RNAs, other mechanisms such as mechanical cues, sibling cell size asymmetry or organelle asymmetry could potentially also contribute to binary cell fate decisions. Here, I propose to use asymmetrically dividing Drosophila neuroblasts, the neural stem cells of the developing fly central nervous system, to investigate the cell and mechanobiology of ACD in vivo. Recently, we discovered that Non-muscle Myosin II-dependent cortical flows, induced through both polarity- and spindle-dependent cues, are implicated in the generation of sibling cell size asymmetry. I will investigate how cortical flows are induced and modulated with spatiotemporal precision to achieve reproducible sibling cell size asymmetry. Our recent discovery of Protein Kinase N (PKN), and the Rho GTPase pathway as inducers of cortical flows will provide molecular entry points. I will also investigate how cell size asymmetry contributes to cell fate decisions, using RNA sequencing, immunohistochemistry, and long-term live cell imaging in vivo. A second project encompassed in this research direction is aimed at investigating the molecular mechanisms and function of molecular centrosome asymmetry, which is manifested in biased microtubule organizing center (MTOC) activity in interphase. We identified new proteins and mechanisms, such as Kinesins, Pp4 and dynamic centriolar protein localization in mitosis, regulating centrosome asymmetry. Centrosome segregation is highly stereotypic in stem cells, but whether and how centrosome asymmetry affects cell fate decisions, remains to be resolved. We will use fly neural stem cells to investigate the mechanisms and functions of centrosome asymmetry during ACD. I am particularly interested in investigating whether centrosome asymmetry provides a mechanism for biased cell fate determinant segregation, either via asymmetric RNA or sister chromatid segregation. I will also investigate whether biased MTOC activity impacts transcriptional regulation via chromatin organization. This research program will benefit from several novel and innovative tools, consisting of live cell imaging, superresolution microscopy, RNA sequencing and acute protein mislocalization and perturbation systems (nanobody, optogenetics), which my lab implemented to probe cytoskeletal dynamics with high spatial and/or temporal precision in vivo. ACD is an evolutionary conserved mechanism and the proposed research program is medically significant because defects in ACD can cause neurodevelopmental disorders or cancer.