Mechanisms of Polyploidy and Aneuploidy in the Liver

肝脏多倍体和非整倍体的机制

• 批准号: 8796891
• 负责人: ANDREW W DUNCAN
• 金额: $ 43.53万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-25 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8796891
• 关键词: Affect; Age; American; Aneuploid Cells; Aneuploidy; Biology; Cause of Death; Cell division; Cell physiology; Cells; Chromosome Segregation; Chromosomes; Chronic; Data; Development; Diploidy; Disease; Disease Resistance; Gene Expression; Genes; Genome; Goals; Hepatic; Hepatocyte; Homeostasis; Human; Individual; Injury; Knockout Mice; Laboratories; Life; Liver; Liver Dysfunction; Liver Regeneration; Liver diseases; Mammals; Measures; Mediating; MicroRNAs; Modeling; Molecular; Molecular Profiling; Mus; Natural regeneration; Nodule; Organ; Organism; Physiological; Ploidies; Polyploidy; Process; Research; Role; Signal Transduction; Steatohepatitis; Testing; Therapeutic; Tissue-Specific Gene Expression; Tyrosinemias; Variant; Viral hepatitis; Xenograft procedure; Yeasts; base; biological adaptation to stress; cell type; chronic liver disease; improved; innovation; insight; liver function; liver injury; liver repair; mouse model; novel; postnatal; public health relevance; regenerative; research study; response

DESCRIPTION (provided by applicant): Nearly 25 million Americans are affected by liver dysfunction, and liver diseases are the 10th leading cause of death in the US. There is a clear and urgent need for developing new alternatives to whole organ replacement. A better understanding of liver biology is required to improve existing approaches and to innovate therapies for the treatment of liver diseases, including viral hepatitis and steatohepatitis. Hepatocytes, the primary functional cell type in the liver, display a range of chromosomal diversity resulting from prevalent physiological polyploidy (>90% in mice and 50% in humans) and aneuploidy (60% in mice and 30-90% in humans). In eukaryotic organisms, cells usually contain a diploid genome comprised of pairs of homologous chromosomes. Polyploidy refers to gains in entire sets of chromosomes, and aneuploidy refers to gains and losses of individual chromosomes. The roles of hepatic polyploidy and aneuploidy represent a major gap in our current understanding of liver biology. We recently found that aneuploidy enhances the regenerative capacity of the mouse liver. In response to Tyrosinemia-induced injury, that is normally toxic to the liver, we identified a subset of aneuploid hepatocytes that was resistant to the disease. The data suggest that aneuploid hepatocytes are endowed with enhanced capacity for adaptation and regeneration. Our central hypothesis is that aneuploidy functions as an adaptive mechanism in response to hepatic injury. The goals of this application are to identify mechanisms regulating hepatic aneuploidy/polyploidy and to unravel how aneuploidy affects liver function. To investigate these questions, we propose in Specific Aim 1 to determine whether polyploid hepatocytes are necessary for development of aneuploid livers. Experiments will characterize hepatic cell divisions, karyotypes and stress response in E2f7/E2f8 knockout mice, which have normal liver function but are depleted of polyploid hepatocytes. In Specific Aim 2, we will dissect the role of a novel regulator of hepatic polyploidy, recently identified in ur laboratory, microRNA-122 (miR-122). Experiments will determine how miR-122 alters ploidy and aneuploidy throughout life. We will also identify cellular and molecular mechanisms by which miR-122 regulates hepatic ploidy. Finally, in Specific Aim 3, we will determine how random karyotypes (in aneuploid hepatocytes) affect function in the liver. We will utilize a novel xenotransplantation model to examine clonal nodules of regenerating human hepatocytes. Experiments will measure aneuploidy and determine gene expression profiles in these nodules. Together, these studies will define the extent to which aneuploidy affects liver repair/regeneration as well as the molecular mechanisms that control this process. Understanding how aneuploid hepatocytes arise and function will provide new and crucial insights into liver homeostasis, diseases and treatments.

描述（由申请人提供）：将近2500万美国人受肝功能障碍的影响，肝病是美国第十大死亡原因。显然和迫切需要开发整个器官替换的新替代方法。需要更好地了解肝脏生物学，以改善现有方法并创新治疗肝病的疗法，包括病毒肝炎和脂肪性肝炎。肝细胞是肝脏中的主要功能性细胞类型，显示出一系列由普遍的生理多倍体引起的染色体多样性（小鼠的> 90％，人类> 90％）和非整倍性（小鼠的60％，人类为30-90％）。在真核生物中，细胞通常包含由成对同源染色体组成的二倍体基因组。多倍体是指在整个染色体中的增长，而非整倍性是指单个染色体的增长和损失。肝多倍体和非整倍性的作用代表了我们当前对肝生物学的理解。我们最近发现，非整倍性增强了小鼠肝脏的再生能力。为了应对酪氨酸诱导的损伤，通常对肝脏有毒，我们确定了对疾病具有抗性的非整倍性肝细胞的子集。数据表明，非整倍型肝细胞具有增强的适应能力和再生能力。我们的核心假设是，针对肝损伤，非整倍性作为一种适应性机制。该应用的目标是确定调节肝非整倍性/多倍体的机制，并揭示非整倍性如何影响肝功能。为了调查这些问题，我们在特定的目标1中提出，以确定多倍体肝细胞是否对于开发非整倍体肝脏是必需的。实验将表征E2F7/E2F8敲除小鼠的肝细胞分裂，核型和应力反应，这些小鼠具有正常的肝功能，但被多倍型肝细胞耗尽。在特定的目标2中，我们将剖析最近在UR实验室MicroRNA-122（miR-122）中鉴定出的新型肝多倍体调节剂的作用（miR-122）。实验将确定miR-122在一生中如何改变倍增性和非整倍性。我们还将确定miR-122调节肝倍性的细胞和分子机制。最后，在特定的目标3中，我们将确定随机核型（在非整倍型肝细胞中）如何影响肝脏的功能。我们将利用一种新型的异种移植模型来检查重生人肝细胞的克隆结节。实验将测量非整倍性并确定这些结节中的基因表达谱。这些研究共同定义了针对肝修复/再生以及控制这一过程的分子机制的程度。了解非整倍型肝细胞如何出现和功能将为肝稳态，疾病和疗法提供新的至关重要的见解。