Specialized post-transcriptional mechanisms of gene expression in quiescence

静止期基因表达的特殊转录后机制 视觉静止(G0)是一组可逆的、细胞周期停滞的阶段，允许细胞避免 在恶劣的条件下死亡。G0在免疫和癌症中起关键作用，促进炎症和适应 对于疾病的持久性；然而，尽管G0具有医学意义，但人们对它知之甚少。我们的研究 在G0细胞中发现了强大的RNA调节和修饰，揭示了对常规 翻译和非规范机制的替代，以实现G0角色的特定基因表达 和生存。根据我们的数据，G0细胞由特殊的转录后机制永久化， 诱导特定的基因表达，维持短暂的停滞状态，使G0在应激中存活 条件，并保留G0细胞重新进入细胞周期和持续疾病的能力。这允许 重要的G0功能：白血病等恶性肿瘤的药物和免疫存活，免疫细胞外渗， 组织再生和发育。我们研究的目标是研究不同的转录后 在G0白血病细胞中的机制和基因表达，以了解G0在疾病中的作用和持久性。 前提我们研究的关键发现是传统的翻译被G0信号抑制而被取代 通过非规范因子实现对生存至关重要的基因的特定表达。值得注意的是， 这些非规范因素改变了翻译起始点的选择，通过创建新的 框架(PNAS 2014)。我们识别了非编码RNA、相关的RNA-蛋白质复合体(RNP)和非编码的 在G0中调节少数免疫和细胞状态调节因子选择性表达的典型翻译因子 (分子细胞2016)。我们的数据揭示了改变G0中的RNPs以启用特定基因的信号变化 表达，这使得在疾病中靶向抗药性G0(基因组生物。2020)。我们的研究表明 未被发现的调控的重要层面：核糖体、mRNAs和RNPs的修饰及其相关 非规范翻译(科学2020，NAT。交警。2020年，科学进展2022年)。G0的刻画 转录后变化，将揭示推动疾病持久性G0存活的隐藏机制。 未来5年的发展方向首先是分析、提纯、耗竭、突变和生化分析 将绘制snoRNPs和核糖体修饰图，提供对以下变化的见解 G0存活期基因表达的翻译机制。第二，对mRNAs的修饰， G0中的相关RNP、非规范翻译因素、翻译目标和唯一起点将是 识别以揭示G0翻译组，在翻译框架处展开。最后，将在以下方面进行验证 在体内和患者样本中，以揭示影响G0角色和持久性的转录后机制。 这些研究将揭示对G0转录后机制的新见解，提供一张地图 核糖体和RNA修饰，以及翻译框架，以及它们对G0角色和疾病存活率的影响。

Abstract Specialized post-transcriptional mechanisms of gene expression in quiescence Vision Quiescence (G0) is an assortment of reversible, cell-cycle arrested phases that permits cells to avoid death due to harsh conditions. G0 is critical in immunity and cancer, promoting inflammation and adaptations for disease persistence; however, G0 is poorly understood despite its medical significance. Our studies uncovered powerful RNA regulators and modifications in G0 cells, revealing inhibition of conventional translation and its replacement by non-canonical mechanisms to enable specific gene expression for G0 roles and survival. Based on our data, G0 cells are perpetuated by specialized post-transcriptional mechanisms that elicit specific gene expression, which maintains the transient arrested state, enables G0 survival in stress conditions, and retains the ability of G0 cells to re-enter the cell cycle and persist disease. This permits important G0 functions: drug and immune survival in malignancies like leukemia, immune cell extravasation, tissue regeneration, and development. The goal of our study is to investigate the distinct post-transcriptional mechanisms and gene expression in G0 leukemic cells, to understand G0 roles and persistence in disease. Premise The key finding of our studies is that conventional translation is inhibited by G0 signals and replaced by non-canonical factors that enable specific expression of genes that are critical for survival. Significantly, such non-canonical factors alter translation start site selection, expanding the proteome by creating new frames (PNAS 2014). We identified noncoding RNAs, associated RNA-protein complexes (RNPs), and non- canonical translation factors that mediate select expression of few immune and cell state regulators in G0 (Molecular Cell 2016). Our data reveal signaling changes that modify RNPs in G0 to enable specific gene expression, which allowed targeting of drug resistant G0 in disease (Genome Biol. 2020). Our studies indicate important layers of undiscovered regulation: modification of ribosomes, mRNAs and RNPs and associated non-canonical translation (Science 2020, Nat. Commun. 2020, Science Adv. 2022). Characterization of G0 post-transcriptional changes, will reveal hidden mechanisms that drive G0 survival for disease persistence. Directions in the next 5 years First, profiling, purifications, depletions, mutations, and biochemical analyses of snoRNAs and ribosomes, will map snoRNPs and ribosome modifications, providing insights on changes to the translation machinery underlying gene expression in G0 survival. Second, modifications on mRNAs, associated RNPs, non-canonical translation factors, translated targets and unique start sites in G0 will be identified to uncover the G0 translatome, expanded at the translation frame. Finally, these will be verified in vivo and in patient samples, to uncover post-transcriptional mechanisms that impact G0 roles and persistence. Impact These studies will uncover new insights into G0 post-transcriptional mechanisms, provide a map of ribosome and RNA modifications, and translation frames, and their impact on G0 roles and survival in disease.