CAREER: Asymmetric ER partitioning as a pathway for cell fate specification

这个提议解决了多细胞生物中的一个重要问题，即细胞多样性。 细胞多样性是通过不对称的细胞分裂实现的，其中产生的两个子细胞具有不同的命运。在分裂过程中产生不同细胞命运的机制可以由母细胞本身（内在）或细胞外的因素（外在）产生。 多细胞生物体中枢神经系统（CNS）的发育依赖于影响细胞不对称分裂的外在和内在因素，但对这些因素的性质知之甚少。 这项研究的目的是确定一种内在因素，导致产生具有不同细胞命运的子细胞。 这项工作将在果蝇中进行，果蝇是一个杰出的研究模型，导致了许多发现。 重要的是，这些在果蝇中的发现为我们提供了许多关于其他多细胞生物（包括人类）发育的知识。 PI的初步数据表明，内质网（ER）是细胞的主要和关键的内在成分，在细胞分裂期间存在不对称分配。 雌激素受体在随后的细胞亚群分裂之前不均匀地分配到一个子细胞中，这些细胞亚群最终将发育成成年果蝇的中枢神经系统。 核心假设是ER是不对称分配的，用于建立决定细胞命运的关键线索。 实验的设计，将提供新的见解的问题，细胞多样性的产生，在生物学中的一个基本问题。 在更广泛的科学层面上，拟议的研究将通过促进科学，技术，工程和数学（STEM）领域的多样性来整合研究和教育。这将通过创建生物学本科生导师计划（BUMP）来实现，并将利用近同行指导的技术来招募和保留STEM专业的学生。 此外，BUMP导师和学员将在当地小学提供社区服务机会，满足全国对更多STEM指导的需求。PI的长期研究目标是调查细胞不对称的机制，并确定负责决定细胞命运的信号。拟议的研究的目标是定义涉及细胞命运决定因素的遗传途径，并使用模式生物果蝇（Drosophila melanogaster）确定参与其运输和分配的新靶标。核心假设是，由于高度保守的跨膜蛋白Jagunal（Jagn）与细胞皮质的相互作用，ER被不对称地分配，并负责建立关键的细胞命运决定因素。PI将是第一个研究Jagn在不对称细胞分裂中的作用，并已证明在神经上皮中观察到的ER的不对称分配是Jagn依赖的。PI将采用遗传学和体内细胞学方法来研究Jagn对发育和神经细胞命运的作用。此外，PI将涉及本科研究人员，通过对果蝇基因组进行基于显性修饰子的筛选，以确定与Jagn相互作用的靶点，从而控制有丝分裂期间的不对称ER分配。本申请中提出的实验将为细胞多样性产生的更大问题提供新的见解，并有可能为不对称分裂的新模型开辟新的领域。

This proposal addresses an important problem in multicellular organisms; namely cellular diversity. Cellular diversity is achieved through an asymmetric cell division, in which two produced daughter cells have different fates. The mechanism that generates different cell fates, during division, can either be generated by the mother cells itself (intrinsic) or by factors outside of the cell (extrinsic). Development of the central nervous system (CNS) in multicellular organisms relies on both extrinsic and intrinsic factors that affect asymmetric cell divisions, but the nature of these factors are poorly understood. The goal of the proposed research is to define an intrinsic factor that leads to the production of daughter cells with different cellular fates. This work will be performed in the fruitfly, Drosophila melanogaster, which has served as an outstanding research model leading to many discoveries. Importantly, these discoveries in the fruitfly, has informed much of our knowledge involving the development of other multicellular organisms (including humans). The PI has preliminary data demonstrating an asymmetric partitioning during cell division of the Endoplasmic Reticulum (ER), a major and critical intrinsic component of the cell. The ER is partitioned unequally into one daughter cell prior to the subsequent division of a subset of cells that will eventually develop into the CNS of the adult fly. The central hypothesis is that the ER is partitioned asymmetrically for the establishment of key cues that dictate cellular fate. Experiments are designed that will provide new insight into the issue of the generation of cell diversity, a fundamental question in biology. On the broader scientific level, the proposed research will integrate research and education by promoting diversity in Science, Technology, Engineering and Math (STEM) field. This will be accomplished by the creation of a Biology Undergraduate Mentor Program (BUMP) and will utilize the technique of near-peer mentoring for the recruitment and retention of students within STEM majors. Furthermore, BUMP mentors and mentees will provide community service opportunities at a local elementary school addressing the national need for more STEM mentoring.The PI's long-term research goal is to investigate the mechanisms of cell asymmetry and identify the signal(s) responsible for determining cell fate. The goal of the proposed research is to define the pathway of inheritance involving cell fate determinants and identify novel targets involved in the their transport and partitioning using the model organism, Drosophila melanogaster. The central hypothesis is that the ER is partitioned asymmetrically due to the interaction of the highly conserved transmembrane protein Jagunal (Jagn) with the cell cortex and is responsible for the establishment of key cell fate determinants. The PI will be the first to investigate the role of Jagn in asymmetric cell division and has demonstrated that the asymmetric partitioning of the ER observed in the neural epithelia is Jagn dependent. The PI will employ both genetic and in vivo cytological approaches to investigate the role of Jagn on development and neural cell fate. In addition, the PI will involve undergraduate researchers to identify targets that interact with Jagn by performing a dominant modifier-based screen of the Drosophila genome towards control asymmetric ER partitioning during mitosis. The experiments set forth in this application will provide new insight into the larger issue of the generation of cell diversity and has the potential to open the field to new models of asymmetric divisions.