Transcriptional regulation of mammary gland development

乳腺的发育和功能需要精确的阶段和空间控制 转录程序。这些过程受到严格控制，以确保功能的成功 乳腺的，包括哺乳，这是养育后代所必需的。近期工作 已经证明了E2F转录因子的作用远远超出了它们传统的 在细胞周期调控中的作用。活化剂E2FS(E2F1-3a)的作用被很好地表征， 包括对乳腺发育的调控。然而，人们对该组织的作用知之甚少。 乳腺中的抑制子E2F、E2F4和E2F5，部分原因是脑积水 以及基因敲除菌株的早期致死性。我们工作的长期目标是确定 乳腺发育和功能中的转录调控。了解正常 然后，生物学告诉我们的研究这是如何出错并导致乳腺癌的。这个 这项提议的近期目标，也就是我们长期目标的下一步，正是为了 确定抑制子E2F在乳腺中的作用。我们的中心假设是 抑制子E2F调控关键的乳腺发育基因。这一假设是基于 根据基因敲除小鼠的初步数据。事实上，E2F5在乳腺上皮中的丢失导致了 青春期导管延长延迟、退缩延迟和肺泡过度生长 成年小鼠。E2F4的缺失也会导致导管发育延迟，但也与 妊娠和哺乳期间肺泡严重缺乏扩张。合并ChIP-Seq数据 和我们的基因表达数据，我们预测了独特的和共享的E2F靶基因 乳房发育的作用。拟议工作的基本原理是，一旦我们有了 完成这项提议后，我们将了解转录抑制如何调节 乳腺的发育。我们计划测试我们的中心假设，并实现 通过调查以下具体目的来实现这一应用的目标。在第一个目标中，我们将 表征与乳腺上皮细胞特异性相关的乳腺表型 E2F5基因的敲除。第二个目标是生成CHIP-SEQ数据，并将其与E2F5集成 诱导基因表达数据确定E2F5靶点。目标基因将被过滤并 使用描述乳房发育的其他数据集确定优先顺序。最后，在第三个目标中 我们将检查缺少E2F3或E2F5的处女腺的scRNAseq数据。这个建议很有新意 因为它将阐明调控乳腺发育和 由抑制因子E2F转录因子发挥作用。这一贡献意义重大，因为它将 确定E2F5在乳腺发育中的作用。

Mammary gland development and function requires precise stage and spatial control of transcriptional programs. These processes are tightly controlled to ensure the successful function of the mammary gland, including lactation which is essential for rearing of offspring. Recent work has demonstrated a role for the E2F transcription factors that goes well beyond their traditional role in cell cycle regulation. The role of the activator E2Fs (E2F1-3a) is well characterized, including regulation of mammary gland development. However, little is known of the role of the repressor E2Fs, E2F4 and E2F5, in the mammary gland and this is partially due to hydrocephaly and early lethality in the knockout strains. The long term goal of our work is to define the role of transcriptional regulation in mammary gland development and function. Understanding normal biology then informs our studies of how this goes awry and results in breast cancer. The immediate objective of this proposal, which is the next step in our long-term goal, is to precisely define the role of repressor E2Fs in the mammary gland. Our central hypothesis is that the repressor E2Fs regulate key mammary gland developmental genes. This hypothesis was based on preliminary data from knockout mice. Indeed, loss of E2F5 in the mammary epithelium resulted in delayed ductal extension during puberty, delayed involution and alveolar overgrowth in virgin adult mice. Loss of E2F4 also resulted in delayed ductal outgrowth but was also associated with a profound lack of alveolar expansion during pregnancy and lactation. Combining ChIP-Seq data and our gene expression data, we predicted both unique and shared E2F target genes with mammary development roles. The rationale for the proposed work is that once we have completed this proposal, we will understand how transcriptional repression regulates development of the mammary gland. We plan to test our central hypothesis and accomplish the objective of this application by investigating the following specific aims. In the first aim we will characterize the mammary gland phenotypes associated with the mammary epithelial cell specific knockout of E2F5. In the second aim we will generate ChIP-Seq data and integrate it with E2F5 induced gene expression data to determine E2F5 targets. Target genes will be filtered and prioritized using additional datasets describing mammary development. Finally, in the third aim we will examine scRNAseq data in virgin glands lacking E2F3 or E2F5. This proposal is innovative because it will elucidate the genetic mechanisms regulating mammary gland development and function by the repressor E2F transcription factors. This contribution is significant because it will establish a role for E2F5 in mammary gland development.