Defining post-transcriptional regulons in intestinal epithelial regeneration

辐射、炎症、感染和毒素可损害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至关重要。转录后调节子是主要由RNA结合蛋白调节的功能相关的mRNA组，其能够对细胞损伤进行快速的组织特异性反应。这种类型的调节在高度增殖的组织如肠上皮中特别重要，其中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，以增强肠上皮再生和改善患者的治疗，特别是那些经历了由于放疗或化疗导致的胃肠道上皮损伤的患者。我们最近发现，在肠上皮缺失IMP 1（IGF 2 mRNA结合蛋白1;也称为IGF 2BP 1）的小鼠中，上皮再生得到增强，部分原因是通过上调自噬途径。自噬是细胞适应和生存的一种机制。例如，最近对自噬基因缺失的小鼠模型的研究表明，对辐射诱导的组织损伤的易感性增加。定义IMP 1和自噬之间的联系将有助于一个新兴的转录后调节子的范式，作为胃肠道上皮再生的关键调节因子。目的1将研究IMP 1调节自噬基因翻译的分子机制。我们将使用细胞生物学检测以及核糖体分析，在上皮细胞与IMP 1缺失的小鼠，以确定IMP 1在自噬（和其他）基因翻译的直接作用。目的2将评估如何IMP 1介导的自噬的变化有助于干细胞动力学在稳态使用小鼠模型，自噬测定，和肠形成测定。目的3将评估IMP 1在辐射诱导的损伤和随后的再生过程中自噬介导的修复中的肠干细胞特异性作用。我们将使用IMP 1缺失的小鼠模型以及自噬的化学或遗传缺失来定义IMP 1在辐射诱导的损伤和再生过程中如何正常发挥作用，以及这是否是自噬依赖的。该提案的成功完成具有潜在的科学和临床影响，并将为放射诱导（和潜在的其他）肠上皮损伤患者提供改进或新型治疗的基础。

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.