MECHANISMS OF CHIEF CELL DEDIFFERENTIATION

项目总结 我们研究了损伤和炎症是如何诱导成熟细胞的，比如消化酶分泌的酵母菌。 细胞(ZC)分解其复杂的细胞结构，重新进入细胞周期。我们之前已经证明了 ZCs通过一系列在许多组织中保守的分子细胞事件而变得增殖 在这种情况下，成熟细胞被重新招募到细胞周期中，以应对组织损伤。 因此，细胞对这种重新编程有一个进化上保守的程序，就像它们对死亡(细胞凋亡)所做的那样。 和分裂(有丝分裂)。我们将这一程序称为掌叶病，并表明成熟细胞：首先降解/再循环 它们的分化细胞成分(阶段1)，然后诱导祖细胞样基因的表达(例如。SOX9= 阶段2)，最后重新进入细胞周期(阶段3)。棕榈色ZCS转化为可见的细胞 在组织病理学上是指在长期感染霍乱病毒期间发生在胃中的化生类型。 幽门螺杆菌：假性幽门或痉挛多肽表达化生(SPEM)。 化生可以随着组织的修复而消退，也可以变成慢性并增加进展为 不典型增生和癌症。我们已经证明，掌样症是由mTORC1的动态变化控制的， 细胞翻译控制蛋白复合体。在ZCS中，mTORC1在基线处升高，以推动 消化酶，它在阶段1关闭，并在阶段3重新激活。如果没有mTORC1，手掌畸形在 2期细胞呈化生状态，但无法进入S期。 在这里，我们探讨了诱发和促进掌样症的机制。我们展示了初步数据 整合应激反应(ISR)通路作为中枢性手掌症中心在 与ISR相关的转录因子ATF3，以及我们假设的另一个基因 ATF3的靶点：多功能支架蛋白Ifrd1。我们假设大型组织的应力 损伤和/或炎症触发ISR过度活动，导致ATF3和IFRD1显著增加，以 帮助将细胞推回细胞周期。在没有ATF3或Ifrd1的情况下，我们显示手掌畸形是有缺陷的。我们的 具体目标将是：1)确认和进一步确定ISR在哪些阶段活跃，并确认和 使用部分atf3−/−小鼠来表征atf3的作用；2)确定与isr和 通过确定IFRD1在−/−小鼠中的作用，探讨IFRD1ATF3和IFRD1a的相对贡献 通过对双基因敲除小鼠进行鉴定，最后进行CHIP-和RNA-SEQ； 3)测试已知的ATF3和ISR基因以及在目标2中开发的更具生理性的新靶点 疾病模型(如慢性感染幽门螺杆菌的小鼠)、人类翻译样本(组织芯片 以及近1000名患者的化生和癌症的额外人类样本)，以及在小鼠模型中 肿瘤形成±ATF3。总之，这些实验可能有助于我们理解细胞使用的基本机制 在再生和肿瘤形成方面，不仅适用于胃，还可能适用于其他器官。

PROJECT SUMMARY We study how injury and inflammation induce mature cells like the digestive-enzyme-secreting zymogenic chief cell (ZC) to disassemble their complex cell architecture and re-enter the cell cycle. We previously showed that ZCs become proliferative via a sequence of molecular-cellular events conserved across many tissues and species in scenarios where mature cells are recruited back into the cell cycle in response to tissue damage. Thus, cells have an evolutionarily conserved program for this reprogramming, as they do for death (apoptosis) and division (mitosis). We call this program paligenosis and showed that mature cells: first degrade/recycle their differentiated cell components (Stage 1), then induce expression of progenitor-like genes (eg. Sox9 = Stage 2), and finally re-enter the cell cycle (Stage 3). Paligenotic ZCs convert to cells that can be seen histopathologically as the type of metaplasia that occurs in stomach during long-term infection with the bacterium Helicobacter pylori: pseudopyloric or Spasmolytic Polypeptide Expressing Metaplasia (SPEM). Metaplasia can either resolve as tissue is repaired or become chronic and increase risk for progression to dysplasia and cancer. We have shown that paligenosis is governed by dynamic changes in mTORC1, the cellular translation control protein complex. mTORC1 is elevated at baseline in ZCs to drive translation of digestive enzymes, it shuts off at Stage 1, and reactivates at Stage 3. Without mTORC1, paligenosis stops at Stage 2 with cells looking metaplastic, but unable to enter S-phase. Here, we explore the mechanisms that induce and promote paligenosis. We show preliminary data implicating the Integrated Stress Response (ISR) pathway as a central paligenosis hub with a particular role for the transcription factor Atf3, which is associated with the ISR, and another gene which we hypothesize is a target of ATF3: Ifrd1, a multifunctional scaffolding protein. We hypothesize that the stress of large-scale tissue damage and/or inflammation triggers ISR hyperactivity, which leads to greatly increased ATF3 and IFRD1, to help push cells back into the cell cycle. In the absence of Atf3 or Ifrd1, we show paligenosis is defective. Our Specific Aims will be: 1) to confirm and further characterize at which stages ISR is active and confirm and characterize the role for ATF3 using, in part Atf3−/− mice; 2) to identify additional genes involved in the ISR and paligenosis by confirming the role of IFRD1 with Ifrd1−/− mice, probe relative contributions of ATF3 and IFRD1 by characterizing double knockout mice, and finally to perform ChIP- and RNA- Seq during paligenosis ±ATF3; 3) to test known ATF3 and ISR genes and new targets developed in Aim 2 in a pipeline of more physiological disease models (eg chronic infection of mice with H pylori), human translational samples (Tissue Microarray and additional human samples of metaplasia and cancer with nearly a 1000 patients), and in a mouse model of tumorigenesis ±ATF3. Together, the experiments may help us understand fundamental mechanisms cells use in regeneration and tumorigenesis that apply not just to the stomach but potentially other organs as well.