MECHANISMS OF CHIEF CELL DEDIFFERENTIATION

主要细胞去分化的机制

• 批准号: 9329404
• 负责人: Jason C Mills
• 金额: $ 34.31万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-30 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9329404
• 关键词: Address; Affect; Applications Grants; Autophagocytosis; Cell Cycle; Cell Line; Cell Lineage; Cell Proliferation; Cell physiology; Cells; Chief Cell; Chronic; Cytoplasmic Granules; Data; Data Set; Databases; Development; Dose; Enzyme Precursors; Enzymes; Epithelial; FRAP1 gene; Gastric mucosa; Genes; Genetic; Genetic Transcription; Goals; Health; Helicobacter Infections; Helicobacter pylori; Human; In Vitro; Incidence; Infection; Inflammatory; Injury; Lesion; Light; Lysosomes; Malignant Neoplasms; Metaplasia; Metaplastic; Mitotic; Modeling; Molecular; Monomeric GTP-Binding Proteins; Multipotent Stem Cells; Mus; Organ; Organoids; Patient risk; Patients; Pharmaceutical Preparations; Process; Publishing; Recycling; Regulation; Risk; Role; Secretory Vesicles; Seminal; Signal Pathway; Signal Transduction; Specimen; Speed; Stem cells; Stomach; Tamoxifen; Testing; Time; cancer initiation; carcinogenesis; cell dedifferentiation; experimental study; genetic pedigree; human disease; human tissue; injury and repair; malignant stomach neoplasm; novel; pancreatic cell line; prevent; progenitor; programs; public health relevance; repaired; spasmolytic polypeptide; stemness; tissue repair; trafficking; transcription factor

 DESCRIPTION (provided by applicant): It has become clear in just the past two years that many mature cell lineages in digestive organs can dedifferentiate and re-enter the cell cycle to repair tissue damage. We and others have shown that post-mitotic cells can re-induce progenitor cell markers, re-enter the cell cycle, and can even serve as progenitors for other lineages. The dedifferentiation process carries a risk, however, as re-expressing progenitor cell genes is a form of cellular metaplasia. In states of chronic injury, like H. pylori infection in huan stomach, metaplasia continues indefinitely and increases risk for progression to cancer. Overall, cellular dedifferentiation presents a new paradigm for understanding tissue repair, "stemness", and cancer initiation. Our overarching goal is to understand the cellular and molecular mechanisms governing dedifferentiation. Here, we will focus on the earliest stages of dedifferentiation in gastric digestive-enzyme secreting zymogenic chief cells (ZCs). Our preliminary and published data will show that the first stage is engulfment of secretory granules by lysosomes and that lysosomal turnover of the digestive enzyme secretory granules (secretory apparatus "downscaling") must occur before progression to the next stages: metaplastic re- expression of progenitor cell genes and cell cycle re-entry. We will show the earliest molecular change in dedifferentiating ZCs is dramatically decreased expression of the bHLH transcription factor MIST1 (BHLHA15) and that deletion of Mist1 even in healthy ZCs is sufficient to induce lysosomal turnover of secretory granules. Finally, we will show that the only known transcriptional target of MIST1 that traffics lysosomes and is hence the most likely reason for the lysosomal attack on secretory granules when MIST1 is lost during dedifferentiation is the small GTPase, RAB26. Our aims are to: 1) determine the requirement/sufficiency for MIST1 in metaplasia downscaling; 2) determine if RAB26 affects flux through autophagy/mTOR signaling and whether it modulates granule destruction by lysosomes and/or autolysosomes; 3) a) determine if autophagic machinery is required for downscaling by inducing metaplasia following deletion in mature ZCs of the key autophagy genes Atg5 and Atg7 and b) to quantify autophagy/lysosome interaction with secretory granules in a database of human specimens where there are foci of ZCs undergoing dedifferentiation/metaplasia. Together the experiments will uncover for the first time the molecular mechanisms underlying the newly described cellular process of dedifferentiation and will have impact on human health because we will need to understand how metaplastic precursor lesions form from dedifferentiation of mature cells to be able to understand how to revert them and decrease risk for patients to progress to cancer.

 描述（申请人提供）：在过去的两年里，人们已经清楚消化器官中的许多成熟细胞谱系可以去分化并重新进入细胞周期以修复组织损伤。我们和其他人已经证明，有丝分裂后细胞可以重新诱导祖细胞标记，重新进入细胞周期，甚至可以作为其他谱系的祖细胞。然而，去分化过程存在风险，因为祖细胞基因的重新表达是细胞化生的一种形式。在慢性损伤的状态下，例如胃中的幽门螺杆菌感染，化生会无限期地持续，并增加进展为癌症的风险。总体而言，细胞去分化为理解组织修复、“干性”和癌症发生提供了一个新的范例。我们的首要目标是了解控制去分化的细胞和分子机制。 在这里，我们将重点关注胃消化酶分泌酶原主细胞（ZC）去分化的最早阶段。我们的初步和已发表的数据将表明，第一阶段是溶酶体吞噬分泌颗粒，并且消化酶分泌颗粒的溶酶体周转（分泌装置“降级”）必须发生在进入下一个阶段之前：祖细胞基因的化生再表达和细胞周期重新进入。我们将证明去分化 ZC 中最早的分子变化是 bHLH 转录因子 MIST1 (BHLHA15) 的表达显着降低，并且即使在健康 ZC 中删除 Mist1 也足以诱导分泌颗粒的溶酶体周转。最后，我们将证明 MIST1 运输溶酶体的唯一已知转录靶标是小 GTP 酶 RAB26，因此当 MIST1 在去分化过程中丢失时，它是溶酶体攻击分泌颗粒的最可能原因。 我们的目标是：1）确定 MIST1 在化生缩小中的要求/充分性； 2)确定RAB26是否通过自噬/mTOR信号传导影响通量，以及它是否通过溶酶体和/或自溶酶体调节颗粒破坏； 3) a) 确定在成熟 ZC 中删除关键自噬基因 Atg5 和 Atg7 后诱导化生是否需要自噬机制来降低规模，b) 量化自噬/溶酶体与人类样本数据库中分泌颗粒的相互作用，其中存在 ZC 的去分化/化生病灶。这些实验将首次揭示新描述的细胞去分化过程背后的分子机制，并将对人类健康产生影响，因为我们需要了解成熟细胞去分化如何形成化生前体病变，以便能够了解如何恢复它们并降低患者进展为癌症的风险。