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

这一提议解决了多细胞生物体中的一个重要问题，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，在这种分裂中，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既可以由母细胞本身产生(内在的)，也可以由细胞外的因素产生(外在的)。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，但这些因素的性质尚不清楚。这项拟议的研究的目标是确定导致具有不同细胞命运的子代细胞产生的内在因素。这项工作将在果蝇身上进行，果蝇是导致许多发现的杰出研究模型。重要的是，这些在果蝇中的发现为我们提供了许多涉及其他多细胞生物体(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，在细胞分裂过程中存在不对称的分裂。在随后的细胞子集分裂之前，内质网被不平均地划分为一个子细胞，这些子细胞最终将发育成成虫的中枢神经系统。中心假设是，内质网被不对称地划分，以建立决定细胞命运的关键线索。实验的设计将为细胞多样性的产生提供新的见解，这是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，并将利用近乎同行的导师技术来招聘和留住STEM专业的学生。此外，凹凸导师和被辅导者将在当地一所小学提供社区服务机会，以满足全国对更多STEM辅导的需求。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(S)。这项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，并利用模式生物--黑腹果蝇确定参与其运输和分配的新靶点。中心假说是，由于高度保守的跨膜蛋白Jagunal(Jagunal)与细胞皮质的相互作用，内质网被不对称地分割，并负责建立关键的细胞命运决定因素。PI将首次研究Jagn在细胞不对称分裂中的作用，并证明在神经上皮细胞中观察到的ER的不对称分割是Jagn依赖的。PI将使用遗传和体内细胞学方法来研究Jagn在发育和神经细胞命运中的作用。此外，PI将涉及本科生研究人员通过对果蝇基因组进行基于显性修饰物的筛选来确定与Jagn相互作用的靶点，以控制有丝分裂期间不对称的内质网分割。本申请中提出的实验将为细胞多样性的产生这一更大的问题提供新的见解，并有可能为不对称分裂的新模型打开领域的大门。

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.