MOLECULAR REGULATION OF GASTRIC CHIEF (ZYMOGENIC) CELL DIFFERENTIATION

描述（由申请人提供）：慢性胃损伤导致易患更严重疾病的关键细胞谱系分化的改变（例如，癌症）。慢性损伤的胃上皮的特征在于细胞谱系脱落（萎缩）和异常分化（化生）。越来越多的证据表明，消化酶分泌酶原细胞（ZC）在胃萎缩中丢失，此外，ZC谱系的改变在化生中起作用。然而，在正常胃单位或慢性损伤中，对调控ZC分化的细胞或分子过程知之甚少。我们的长期目标是在分子和细胞水平上了解ZC分化，希望更好地了解胃上皮分化在慢性损伤中是如何出错的。我们最近的工作显示了第一个转录因子Mist 1，它在ZC分化中起作用。对Mist 1缺失小鼠的分析表明，在Mist 1缺失的情况下，ZCs不能正常成熟。相反，Mist 1-/-ZC具有显著发育不良的顶端细胞骨架，其特征在于顶端质膜投射和细胞骨架蛋白如肌球蛋白和一般细胞骨架衔接蛋白Cd 2ap（CD 2相关蛋白）的积累。我们还发现，在萎缩的小鼠模型的基础上的细胞显示化生，其特征在于部分，异常ZC分化。有趣的是，这些化生细胞缺乏Mist 1，并增加了Cd 2ap。目前资助的目标集中在确定Mist 1在正常胃单位、萎缩模型和体外人胃细胞系中作用的分子和细胞机制。该基金的目的是：1）确定Mist 1如何在分子水平上与Cd 2ap相互作用（具体来说，Cd 2ap是否受Mist 1的转录调控？）体外在人胃癌细胞中和体内在Cd 2ap/Mist 1双敲除小鼠中; 2）确定Mist 1表达是否足以驱动细胞中的细胞骨架和/或增殖变化;和3）通过激光捕获显微切割Mist 1-/-和野生型ZC谱系细胞，随后通过微阵列鉴定具有Mist 1依赖性表达变化的基因，鉴定Mist 1的新靶标。我们认为Mist 1是胃损伤的领头羊，即，其表达的缺失是表明胃单位处于异常分化的第一击。因此，如果我们了解Mist 1是如何工作的，特别是它与哪些基因相互作用，我们最终可能能够治疗或预防化生或萎缩。人们对使人们易患胃癌的分子和基因知之甚少。该项目旨在进一步了解维持胃粘膜中消化酶分泌细胞正常更新的基因，因为这些细胞似乎是肿瘤发展过程中第一个变得异常的细胞。

DESCRIPTION (provided by applicant): Chronic gastric injury leads to alterations in the differentiation of key cell lineages that predispose to more severe disease (e.g., cancer). Chronically injured gastric epithelium is characterized by cell lineage drop-out (atrophy) and aberrant differentiation (metaplasia). There is growing evidence that the digestive-enzyme secreting zymogenic cell (ZC) is lost in gastric atrophy, and furthermore, that alterations in the ZC lineage play a role in metaplasia. However, little is known about the cellular or molecular processes regulating ZC differentiation either in normal gastric units or in chronic injury. Our long-term objective is to understand ZC differentiation at the molecular and cellular level in hopes of better understanding how gastric epithelial differentiation goes awry in chronic injury. Our recent work has shown the first transcription factor, Mist1, which plays a role in ZC differentiation. Analysis of Mist1 null mice indicates that, in the absence of Mist1, ZCs do not mature normally. Rather, Mist1-/- ZCs have remarkably stunted apical cytoplasms characterized by apical plasma membrane projections and accumulation of cytoskeletal proteins like myosin and the general cytoskeletal adaptor protein Cd2ap (CD2-associated protein). We also show that the cells in the bases of a mouse model of atrophy show metaplasia, characterized by partial, aberrant ZC differentiation. Interestingly, these metaplastic cells lack Mist1 and have increased Cd2ap. The goals of the current grant are focused on determining the molecular and cellular mechanisms of Mist1 action in normal gastric units, in a model of atrophy, and in vitro in human gastric cell lines. The aims of the grant are to: 1) to determine how Mist1 interacts with Cd2ap at the molecular level (specifically, is Cd2ap transcriptionally regulated by Mist1?) in vitro in human gastric cancer cells and in vivo in Cd2ap/Mist1 double knockout mice; 2) to determine whether Mist1 expression is sufficient to drive cytoskeletal and/or proliferative changes in cells; and 3) to identify new targets of Mist1 by laser-capture microdissecting Mist1-/- and wildtype ZC lineage cells followed by microarray identification of genes with Mist1-dependent expression changes. We propose that Mist1 is the bellwether for gastric injury, i.e., that loss of its expression is a first hit that indicates the gastric unit is on a path to aberrant differentiation. Thus, if we understand how Mist1 works, especially what genes it interacts with, we might be able eventually to treat or prevent metaplasia or atrophy. Little is known about the molecules and genes that predispose people to developing gastric cancer. This project aims to further our understanding of the genes that maintain normal renewal of the digestive enzyme secreting cells in the stomach lining, because it is these cells that seemingly are the first to become aberrant on the way to tumor development.