Role of Mitochondria as Intracellular Shuttles for Nuclear Gene-regulatory Transcription Factors During Pluripotent Cell Division and Fate Specification

在哺乳动物中，受精是通过卵子和精子结合产生单细胞受精卵而发生的。这个单细胞分裂几次，形成一个由大约100个相同细胞组成的囊胚，但随后会做出所谓的细胞命运决定：一些囊胚细胞将发育成胚胎，而其他细胞将发育成胎盘，胎盘会使发育中的胚胎发育不良。 发育生物学中一个长期存在的问题是“早期囊胚中的哪些因素触发了细胞命运决策？” 这个项目将探索这样一个假设，即细胞的能量生产工厂，称为线粒体，通过充当穿梭机来传递驱动细胞交替命运的因子，从而指导细胞命运的决定。 新技术将用于比较小鼠胚胎和胎盘细胞中线粒体的特征，如大小、能量分布和蛋白质组成。 这些结果有望揭示细胞命运决策的关键步骤，并揭示线粒体在这一过程中以前未知的作用。 在这项研究期间，来自不同背景的本科生和研究生将参加创新培训活动，使用最先进的科学工具来打造生物学和技术的新发现，旨在更深入地了解细胞命运是如何调节的。该项目还将实施一项创新的团队指导战略，以扩大有兴趣追求科学，技术，工程，数学（STEM）为基础的职业生涯的本科生参与研究的机会，重点是历史上在STEM中代表性不足的学生群体。解密指导细胞命运的核心机制仍然是器官发育，功能，衰老和疾病的高优先级研究领域。 哺乳动物中的第一个细胞命运决定，即驱动内细胞团（注定成为胚胎）和滋养外胚层（TE;注定成为胎盘）的形成，发生在植入前胚胎发生的后期阶段。 虽然已经提供了几种模型来解释这个过程是如何编排的，但胚胎细胞谱系特化的实际起始驱动因素的身份仍然未知。 到目前为止，最早确定的命运决定信号之一是TEA结构域转录因子4（Tead 4），它激活TE身份所需的基因转录。 支持其在细胞命运规范中的关键作用，小鼠中Tead 4基因的破坏产生无法产生TE的桑椹胚，导致胚胎致死。 由于Tead 4被鉴定为胚胎细胞命运决策中最早的信号之一（如果不是最早的话），目前尚不清楚Tead 4的功能如何仅限于那些注定形成TE的细胞。 该项目将联合收割机结合线粒体亚群分析的技术进步与线粒体谱系追踪方法，以测试线粒体亚型的差异分配的假设，这在其生化特性以及蛋白质组学景观-包括Tead 4内化-在胚胎发育过程中驱动细胞谱系命运决定。 通过测试线粒体亚型异质性和细胞器间通讯对TE与ICM规范的意义，本项目将评估线粒体异质性是否指导细胞命运确定，也许通过一个作为-线粒体在不对称细胞分裂中作为转录因子“穿梭机”的作用尚未被发现。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准。

In mammals, fertilization occurs through the joining of an egg and a sperm to produce a single-cell zygote. This single cell divides a few times to form a blastocyst composed of about 100 identical cells, but then a so-called cell fate decision is made: some blastocyst cells will develop into the embryo, and the others will develop into the placenta, which nourishes the developing embryo. A long-standing question in developmental biology is “What factors in the early blastocyst trigger cell-fate decision-making?” This project will explore the hypothesis that the energy-producing factories of cells, called mitochondria, guide cell-fate decisions by acting as shuttles for the delivery of factors that drive alternate cell fates. New technology will be applied to compare mitochondrial features--such as size, energy profiles, and protein makeup--in mouse embryo versus placental cells. The results are expected to shed light on key steps of cell-fate decision-making and uncover a previously unknown role for mitochondria in this process. During this research, undergraduate and graduate students from diverse backgrounds will participate in innovative training activities using state-of-the-art scientific tools to forge new discoveries in biology and technology, geared towards development of a deeper understanding of how cell fate is regulated. The project also will implement an innovative team-mentorship strategy to expand opportunities for undergraduate students interested in pursuing Science, Technology, Engineering, Mathematics (STEM)-based careers to engage in research, with a focus on student populations who are historically underrepresented in STEM.Deciphering the core mechanisms that direct cell fate remains a high-priority research area in organ development, function, aging, and disease. The first cell fate decision in mammals, which drives formation of the inner cell mass (destined to become the embryo) and the trophectoderm (TE; destined to become the placenta), occurs during the later stages of preimplantation embryogenesis. Although several models have been offered to explain how this process is orchestrated, the identity of the actual initiating driver(s) of embryonic cell lineage specification remains unknown. One of the earliest fate-determination signals identified thus far is TEA Domain transcription factor 4 (Tead4), which activates transcription of genes required for TE identity. Supporting its critical role in cell fate specification, disruption of the Tead4 gene in mice generates morulae that fail to generate TE, resulting in embryonic lethality. With Tead4 being identified as one of the, if not the, earliest signal(s) in embryonic cell fate decision-making, it remains unclear how Tead4 function is restricted only to those cells destined to form the TE. This project will combine a technological advancement in mitochondrial subpopulation analysis with a mitochondrial lineage-tracing approach to test the hypothesis that differential allocation of mitochondrial subtypes, which differ in their biochemical properties as well as in their proteomic landscapes--including Tead4 internalization--during embryonic development drives cell lineage fate determination. By testing the significance of mitochondrial subtype heterogeneity and inter-organelle communication to TE versus ICM specification, this project will assess if mitochondrial heterogeneity guides cell fate determination, perhaps through an as-yet undiscovered role for mitochondria as transcription factor ‘shuttles’ during asymmetric cell divisions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.