CELL DIFFERENTIATION WITHIN THE LIVER ACINUS

肝腺泡内的细胞分化

• 批准号: 3231205
• 负责人: JORGE J GUMUCIO
• 金额: $ 16.72万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-04-01 至 1992-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3231205
• 关键词: cell differentiation; cell type; cytochrome P450; embryo /fetus; gene expression; genetic regulation; gestational age; glucose metabolism; histochemistry /cytochemistry; hormone regulation /control mechanism; immunochemistry; immunofluorescence technique; in situ hybridization; laboratory rat; liver cells; mammalian embryology; mature animal; mitochondria; oxygen consumption; phenobarbital; pregnancy

The objective is the elucidation of the molecular mechanisms by which the functional organization of the adult liver acinus is attained. It is our hypothesis that the functional heterogeneity of hepatocytes is necessary to accomplish the ultimate function of the liver acinus, the regulation of solute concentration in the terminal hepatic venule and in bile. We propose that regulation of gene expression is one of the mechanisms by which the functional heterogeneity of hepatocytes develops. Consequently, of particular interest are: a. the changes in gene expression occuring during the transition from fetal to adult liver, and b. the modulation of gene expression within the adult liver acinus. Phenobarbital (PB)-induction of liver cytochromes P-450 b and e (two major BP-inducible forms) will be used as a model since after PB administration, cytochrome P-450 proteins and mRNAs are induced predominantly in hepatocytes of the distal half of the acinus (zones 3 and 2). Specifically, we propose to answer these questions: Is induction of cytochromes P-450 b and e mRNAS occuring in all or in some hepatocytes? Secondly, is the heterogeneous PB-induction of cytochrome P-450 proteins within the liver acinus controlled predominantly at the level of gene transcription? And thirdly, when is this manifestation of hepatocyte heterogeneity established? It is imprinted in fetal life, or does it develop post-natally, and by which molecular mechanisms? In situ hybridization techniques will be used to determine the zonal localization of hepatocytes responding to PB with induction of cytochrome P-450 b and e mRNAs in the adult liver. It will also be used to assess the time of liver development at which the heterogeneous pattern of expression of the PB-inducible cytochrome P-450 genes is attained. In vitro transcription assays using nuclei isolated from hepatocytes of different zones of the adult liver acinus will be used to assess whether differences in transcription rate are the main mechanisms responsible for the heterogenous expression of the cytochromes P-450 b and e genes after PB. By probing the molecular mechanisms involved in the establishment and regulation of cytochrome P-450 b and e gene expression within the hepatic acinus, these experiments should provide insight into regulatory steps which are necessary for the liver to attain the adult organization of the liver acinus.

目的是阐明其分子机制 获得成人肝腺泡的功能组织。 这是我们的 假设肝细胞的功能异质性对于 完成肝腺泡的最终功能，调节 终末肝小静脉和胆汁中的溶质浓度。 我们 提出基因表达调控是其机制之一 肝细胞功能异质性的发展。 最后， 特别感兴趣的是：基因表达发生的变化 从胎儿肝脏到成人肝脏的过渡期间，以及b．的调制 成人肝腺泡内的基因表达。 苯巴比妥 (PB) 诱导肝细胞色素 P-450 b 和 e（两种主要的 BP 诱导因子） 形式）将被用作模型，因为在 PB 给药后，细胞色素 P-450 蛋白和 mRNA 主要在肝细胞中诱导 腺泡的远端一半（区域 3 和区域 2）。 具体来说，我们建议 回答以下问题： 细胞色素 P-450 b 和 e mRNA 的诱导是否有效 发生在全部或部分肝细胞中？ 其次，是异质性 肝腺泡内细胞色素 P-450 蛋白的 PB 诱导 主要控制在基因转录水平？ 第三， 肝细胞异质性的这种表现是什么时候建立的？ 这是 是在胎儿生命中留下印记的，还是在出生后发育的？ 分子机制？ 原位杂交技术将用于 确定肝细胞响应 PB 的区域定位 在成人肝脏中诱导细胞色素 P-450 b 和 e mRNA。 它将 也可用于评估肝脏发育的时间 PB 诱导细胞色素 P-450 的异质表达模式 基因已获得。 使用分离的细胞核进行体外转录测定 将使用来自成人肝腺泡不同区域的肝细胞 评估转录率的差异是否是主要机制 负责细胞色素 P-450 b 的异质表达和 PB后的e基因。 通过探究参与的分子机制 细胞色素 P-450 b 和 e 基因表达的建立和调节 在肝腺泡内，这些实验应该可以深入了解 肝脏达到成年状态所必需的调节步骤 肝腺泡的组织。