Hepatic stellate cell microRNA networks in ethanol-impaired liver regeneration

 描述（由申请人提供）：在正常情况下，肝脏能够在损伤后自我再生;然而，这种能力在乙醇消耗后丧失。肝脏的再生能力取决于实质（肝细胞）和非实质（肝星状细胞，枯否细胞）细胞类型之间协调的信号相互作用。MicroRNA是一类小分子（约22个核苷酸）非编码RNA，在维持细胞正常功能中发挥着重要作用。因此，乙醇诱导的细胞信号正常microRNA调节的破坏可能会影响肝脏进行再生的能力。我的研究将集中在microRNA的作用，特别是在肝星状细胞，产生了一些细胞因子，生长因子，和细胞外基质蛋白的正常肝脏再生功能的重要性。为了研究这个系统，我已经开发了一个计算模型的肝星状细胞激活，其中包括一个过程中引入的两个microRNA的目标-miR-21和miR-146 a的负调控的靶基因。该模型能够描述在肝星状细胞活化过程中转录因子和microRNA水平发生的某些变化，但是通过引入进一步的microRNA调控网络来扩展该模型将提供关于在激活过程中表达的动力学和刺激信号停止后重新正常化的额外信息。因此，该项目的目标是表征参与肝星状细胞活化的调控microRNA基因网络，并通过测试三个假设来了解酒精适应如何导致其失调导致肝再生受损：（1）microRNA平衡以肝星状细胞特异性方式改变，（2）肝星状细胞激活和静止受microRNA网络分布变化控制，和（3）miR-21的抑制导致作为改变的细胞信号传导的结果的从抗再生表型到促再生表型的转变。这些假设将使用各种体内和体外方法进行测试，包括酒精适应大鼠模型，细胞培养，单细胞捕获和分析，以及微阵列研究。此外，现有的肝星状细胞激活模型将得到扩展，计算机模拟研究将用于预测microRNA和靶基因表达对刺激因子的反应。实验验证将有助于梳理出星状细胞激活的机制及其在再生中的作用，并进一步完善模型。我们希望确定哪些microRNA在星状细胞活化中起关键作用，它们调节哪些细胞过程，以及它们对乙醇的反应失调如何导致再生能力受损。

 DESCRIPTION (provided by applicant): Under normal circumstances, the liver is able to regenerate itself following damage; however, this ability is lost following ethanol consumption. The liver's regenerative ability depends on the coordinated signaling interactions between parenchymal (hepatocytes) and non-parenchymal (hepatic stellate cells, Kupffer cells) cell types. MicroRNAs, a class of small (~22 nucleotides) non-coding RNAs, play many important roles in maintaining proper cellular function. Therefore, it is likely that ethanol-induced disrupton of normal microRNA regulation of cell signaling will affect the liver's ability to undergo regeneration. My research will focus on the role of microRNAs specifically in hepatic stellate cells, which produce a number of cytokines, growth factors, and extracellular matrix proteins important for normal liver regenerative function. In order to study this system, I have developed a computational model of hepatic stellate cell activation which includes a process for introducing negative regulation of target genes by two microRNAs of interest-miR-21 and miR-146a. The model is able to describe certain changes that occur in transcription factor and microRNA levels during hepatic stellate cell activation, but expansion of this model with the introduction of furthr microRNA regulatory networks would provide additional information on the dynamics of expression during activation and re-normalization upon cessation of stimulating signals. Therefore, the goal of this project is to characterize the regulatory microRNA-gene networks involved in hepatic stellate cell activation and understand how their dysregulation by alcohol adaptation contributes to impaired liver regeneration by testing three hypotheses: (1) microRNA balances are altered in a hepatic stellate cell-specific manner, (2) hepatic stellate cell activatin and quiescence is controlled by a shift in distributions of microRNA networks, and (3) inhibition of miR-21 results in a shift from an anti- to pro- regenerative phenotype as the result of altered cellular signaling. These hypotheses will be tested using a variety of in vivo and in vitro approaches, including rat models of alcohol adaptation, cell culture, single-cell capture and analysis, and microarray studies. In addition, the existing model of hepatic stellate cell activatin will be expanded, and in silico studies will be used to predict changes in microRNA and target gene expression in response to stimulating factors. Experimental validation will help tease out the mechanisms of stellate cell activation and its role in regeneration, as well as further refine the model. We expect to identify which microRNAs play a key role in stellate cell activation, what cellular processes they regulate, and how their dysregulation in response to ethanol can lead to an impaired regenerative ability.