Role of FGF10 in liver organogenesis and alcohol-impaired regeneration

描述(由申请人提供)：这项建议集中在减少的FGF10信号在乙醇(EtoH)损害肝脏再生的设置中的潜在作用。FgflO在胚胎前肠中胚层表达，通常通过成纤维细胞生长因子受体2 1Mb(FGFR2b)与相邻内胚层相互作用。缺乏通过FGFR2b的信号会导致许多胃肠道结构的失调。我们有初步证据表明，FGF10通过FGFR2b在发育中的肝脏激活典型的WNT信号。我们的研究表明，FGF10由激活的肝星状细胞表达，而星状细胞在肝纤维化形成中起关键作用；FGFR2b在出生前和出生后表达于祖细胞、肝母细胞和卵圆细胞。与FGFR2b信号在肝再生过程中被激活的观察结果一致，我们有证据表明，在乙醇诱导的肝再生受损的背景下，肝部分切除后上调的FGF10表达减少。我们假设乙醇通过FGF10/FGFR2b抑制信号，从而损害祖细胞的增殖。因此，我们提出以下建议 具体目的：(1)研究在转基因小鼠肝部分切除(PH)后无乙醇或无乙醇存在的情况下，FGF10信号通过FGFR2b在肝再生过程中的作用。肝特异性诱导的主要负性可溶性FGFR2b亚型或成纤维细胞生长因子10的过度表达，在无水乙醇损害肝再生的情况下，将分别用于功能丧失或功能获得分析。(2)探讨成纤维细胞生长因子10(FGF10)表达细胞在肝再生和肝再生中的作用。将转基因胚胎肝和PH肝中表达成纤维细胞生长因子10的细胞用荧光激活细胞分选(FACS)和实时荧光定量聚合酶链式反应(Real-time PCR)进行鉴定。(3)确定接受FGF10介导的典型WNT激活的细胞的身份。具有激活的规范WNT信号的细胞将由FACS进行分选。将进行FgflO的功能损失和功能增益分析，以确定规范的WNT激活的相对水平。酒精会损害肝脏自我修复和再生的能力。这导致了肝硬变的发展。我们推测，酒精损害肝再生的机制可能是由于FGF10/FGFR2b通路的信号受损所致，通常情况下，酒精促进肝再生。

DESCRIPTION (provided by applicant): This proposal focuses on the potential role of reduced FGF10 signaling in the setting of ethanol (EtOH) impaired liver regeneration. FgflO, expressed in the embryonic foregut mesoderm, normally interacts with the adjacent endoderm through Fibroblast Growth Factor Receptor 2 1Mb (FGFR2b). Absence of signaling through FGFR2b results in atresias of numerous gastrointestinal tract structures. We have preliminary evidence showing that FGF10 activates canonical WNT signaling in the developing liver through FGFR2b. Our studies indicate that Fgf 10 is expressed by activated hepatic stellate cells, which play a key role in liver fibrogenesis, and that Fgfr2b is expressed by progenitor cells, hepatoblasts prenatally and oval cells postnatally. Consistent with the observation that FGFR2b signaling is activated during liver regeneration, we have evidence that Fgf 10 expression, which is upregulated after partial hepatectomy, is reduced in the setting of ethanol-induced impaired liver regeneration. We hypothesize that ethanol suppresses signaling through the FGF10/FGFR2b, thus, impairing progenitor cell proliferation. We thus propose the following specific aims: (1) To determine the role of FGF10 signaling via FGFR2b during liver regeneration following partial hepatectomy (PH) in the absence or presence of EtOH in transgenic mice. Liver-specific induced overexpression of the dominant negative soluble FGFR2b isoform or of Fgf 10 in the setting of EtOH impaired liver regeneration following PH will be performed for loss-of-function or gain-of-function analyses, respectively. (2) To determine the identity and role of Fgf 10-expressing cells in hepatogenesis and EtOHimpaired liver regeneration. Cells expressing Fgf 10 from transgenic embryo livers and PH livers exposed to EtOH will be sorted by fluorescence activated cell sorting (FACS) and characterized by real-time PCR. (3) To determine the identity of cells undergoing FGF10-mediated canonical WNT activation. Cells with activated canonical WNT signaling will be sorted by FACS. Loss and gain-of function analyses for FgflO will be performed to determine relative levels of canonical WNT activiation. Alcohol impairs the liver's ability to repair and regenerate itself. This contributes to the development of liver cirrhosis. We postulate that the mechanism by which alcohol impairs liver regeneration may be due to impaired signaling through the FGF10/FGFR2b pathway we show normally promotes liver regeneration.