Role of FGF10 in liver organogenesis and alcohol-impaired regeneration

描述（由申请人提供）：本提案侧重于减少FGF10信号在乙醇（EtOH）损害肝脏再生的情况下的潜在作用。FgflO在胚胎前肠中胚层中表达，通常通过成纤维细胞生长因子受体21mb （FGFR2b）与邻近的内胚层相互作用。缺乏通过FGFR2b的信号传导导致许多胃肠道结构的闭锁。我们有初步证据表明，FGF10通过FGFR2b激活发育中的肝脏中的典型WNT信号。我们的研究表明，fgf10在激活的肝星状细胞中表达，在肝纤维形成中起关键作用，Fgfr2b在产前和产后由祖细胞、肝母细胞和卵圆细胞表达。与FGFR2b信号在肝脏再生过程中被激活的观察结果一致，我们有证据表明，在乙醇诱导的肝脏再生受损的情况下，部分肝切除术后上调的Fgf 10表达降低。我们假设乙醇通过FGF10/FGFR2b抑制信号传导，从而损害祖细胞增殖。因此，我们建议如下

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.