Defining post-transcriptional regulons in intestinal epithelial regeneration

辐射、炎症、感染和毒素可破坏胃肠道上皮的完整性。启动、促进和随后减弱再生的机制对于防止长期损伤或疾病是必不可少的。转录后调控因子是一组功能相关的mrna，主要由rna结合蛋白调控，可对细胞损伤产生快速的组织特异性反应。这种类型的调节在肠上皮等高度增殖的组织中尤为重要，在肠上皮中，rna结合蛋白可以作为细胞和组织适应的“变阻器”。我们的总体目标是确定新的策略来增强肠上皮再生和改善患者的治疗，特别是那些由于放射或化疗而导致胃肠道上皮损伤的患者。我们最近发现，肠道上皮缺失IMP1 （IGF2 mrna结合蛋白1，也称为IGF2BP1）的小鼠上皮再生增强，部分原因是自噬途径上调。自噬是细胞在应激反应中适应和生存的一种机制。例如，最近对自噬基因缺失小鼠模型的研究表明，对辐照诱导的组织损伤的易感性增加。确定IMP1和自噬之间的联系将有助于建立一个新兴的转录后调控范式，该范式作为胃肠道上皮再生的关键调节因子。目的1将研究IMP1调控自噬基因翻译的分子机制。我们将使用细胞生物学分析以及Imp1缺失小鼠上皮细胞的核糖体分析来确定Imp1在自噬（和其他）基因翻译中的直接作用。目的2将通过小鼠模型、自噬实验和肠样形成实验来评估自噬中imp1介导的变化如何促进干细胞动态稳态。目的3将评估IMP1在辐照诱导损伤和随后的再生过程中自噬介导的修复中的肠道干细胞特异性作用。我们将使用Imp1缺失与自噬的化学或遗传缺失的小鼠模型来确定Imp1在辐照诱导的损伤和再生过程中如何正常发挥作用，以及这是否依赖于自噬。这一建议的成功完成具有潜在的科学和临床影响，并将为改进或新治疗辐射诱导（和潜在的其他）肠上皮损伤患者提供基础。

Radiation, inflammation, infection, and toxins can damage the integrity of the gastrointestinal epithelium. Mechanisms that initiate, facilitate, and subsequently attenuate regeneration are essential to prevent long-term damage or disease. Post-transcriptional regulons are groups of functionally-related mRNAs regulated primarily by RNA-binding proteins, which enable rapid, tissue-specific responses to cellular damage. This type of regulation is especially important in highly proliferative tissues such as the intestinal epithelium, where RNA-binding proteins may serve as “rheostats” for cellular and tissue adaptation. Our overarching goal is to identify novel strategies to enhance intestinal epithelial regeneration and improve therapies for patients, especially those who experience injury to the gastrointestinal epithelium as a result of radiation or chemotherapy. We discovered recently that epithelial regeneration is enhanced in mice with intestinal epithelial deletion of IMP1 (IGF2 mRNA-binding protein 1; also called IGF2BP1), in part via up-regulation of the autophagy pathway. Autophagy is a mechanism by which cells adapt and survive in response to stress. For example, recent studies in mouse models with autophagy gene deletion demonstrate increased susceptibility to irradiation-induced tissue damage. Defining the link between IMP1 and autophagy would contribute to an emerging paradigm of post-transcriptional regulons that serve as critical regulators of gastrointestinal epithelial regeneration. Aim 1 will examine the molecular mechanisms by which IMP1 regulates autophagy gene translation. We will use cell biology assays as well as ribosome-profiling in epithelial cells from mice with Imp1 deletion to define direct roles for IMP1 in autophagy (and other) gene translation. Aim 2 will evaluate how IMP1-mediated changes in autophagy contribute to stem cell dynamics at homeostasis using mouse models, autophagy assays, and enteroid-formation assays. Aim 3 will evaluate intestinal stem cell-specific roles of IMP1 in autophagy-mediated repair during irradiation-induced injury and subsequent regeneration. We will use mouse models of Imp1 deletion together with chemical or genetic deletion of autophagy to define how IMP1 normally functions during irradiation-induced injury and regeneration and whether this is autophagy-dependent. Successful completion of this proposal has the potential for both scientific and clinical impact and will provide a basis for improved or novel therapies for patients with radiation-induced (and potentially other) injury to the intestinal epithelium.