Gene Regulatory Mechanisms Controlling Tissue Maturation and Polyploidization

I.摘要 多倍体是一种细胞携带两套以上染色体的状态，在自然界中经常观察到， 然而，控制倍性的遗传机制及其功能意义仍然是个谜。肝脏，在 特别是在出生后发育期获得高百分比的多倍体肝细胞; 肝多倍体化的频率和程度在损伤、DNA损伤和 氧化应激，但在肝细胞癌中降低。最近的证据表明， 通过减缓肝细胞的增殖能力和维持肝细胞的增殖能力， 肿瘤抑制剂的储存库。然而，对控制这些疾病的分子事件的了解很少。 出生后肝脏多倍化启动/促进或染色体倍性差异如何影响 肝细胞的转录和转录后活性。我们以前已经证明， RNA结合蛋白ESRP 2是一个关键的发育调控因子，它激活一个成人剪接， 程序，以促进终末分化，功能能力和肝细胞的成熟。的目标 该建议的目的是（i）确定ESRP 2及其剪接的生理必要性/充分性- 调节网络在驱动肝细胞多倍体，和（ii）定义定量和定性的影响， 倍性对肝细胞转录输出的影响。Aim 1将使用ESRP 2功能获得和丧失小鼠模型， 确定通过ESRP 2激活的RNA剪接的程序性变化是否对 肝细胞的多倍化。在目标2中，我们将从二倍体和 多倍体小鼠肝细胞，以研究倍性如何影响稳态水平和替代 在全基因组范围内的肝转录本的剪接模式。拟议的目标将研究新的基因 控制多倍化的调节机制，同时发现以前未被认识到的 选择性剪接和细胞多倍性。

I. ABSTRACT Polyploidy—a state in which cells carry more than two sets of chromosomes—is frequently observed in nature, yet, the genetic mechanisms controlling ploidy and its functional significance remain enigmatic. The liver, in particular, gains a high percentage of polyploid hepatocytes during postnatal period of development; and the frequency and extent of hepatic polyploidization are further increased following injury, DNA damage, and oxidative stress, but are decreased in hepatocellular carcinoma. Recent evidence suggests that polyploidy safeguards the liver from tumorigenesis by slowing the proliferative capacity of hepatocytes and maintaining a reservoir of tumor suppressors. However, there is minimal understanding of the molecular events that govern the postnatal initiation/promotion of hepatic polyploidization or how differences in chromosomal ploidy affect the transcriptional and posttranscriptional activities of hepatocytes. We have previously demonstrated that the RNA binding protein ESRP2 is a key developmentally regulated factor, which activates an adult splicing program to facilitate terminal differentiation, functional competence, and maturation of hepatocytes. The goals of this proposal are to (i) determine the physiological necessity/sufficiency of ESRP2 and its splicing- regulatory-network in driving hepatocyte polyploidy, and (ii) define the quantitative and qualitative impact of ploidy on hepatocyte transcriptional output. Aim 1 will use ESRP2 gain-and loss-of-function mouse models to determine if programmed changes in RNA splicing through ESRP2 activation are crucial for the polyploidization of hepatocytes. In Aim 2, we will generate high-resolution transcriptomes from diploid and polyploid murine hepatocytes to investigate how ploidy influences the steady-state levels and alternative splicing patterns of hepatic transcripts at a genome-wide scale. The proposed aims will examine new gene regulatory mechanism(s) controlling polyploidization while uncovering previously unrecognized links between alternative splicing and cellular polyploidy.