Deletion of the met tyrosine kinase in liver progenitor oval cells increases sensitivity to apoptosis in vitro
Deletion of the met tyrosine kinase in liver progenitor oval cells increases sensitivity to apoptosis in vitro
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DOI：
10.2353/ajpath.2008.070793
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发表时间：
2008-05-01
影响因子：
6
通讯作者：
Sanchez, Aranzazu
中科院分区：
文献类型：
--
作者：
del Castillo, Gaelle;Factor, Valentina M.;Sanchez, Aranzazu
肝细胞生长因子 (HGF)/Met 信号系统对于肝脏发育、稳态和功能至关重要。在这项研究中，我们利用实验室培育的肝脏特异性 Met 条件敲除小鼠来研究成体肝脏祖细胞（卵圆细胞）生物学中 HGF/Met 信号传导的分子机制。为此，我们从经 3,5-二乙氧基羰基-1,4-二氢可力丁处理的 Met(flx/flx) 小鼠中分离出卵圆细胞，并使用病毒介导的 Cre-loxP 重组建立了携带功能性 (Met(flx/flx)) 或非功能性 (Met(-/-)) met 基因的卵圆细胞衍生细胞系。缺乏 Met 酪氨酸激酶活性的卵圆细胞既不表现出 Met 磷酸化，也不表现出下游靶标的激活，并且对 HGF 刺激无效。尽管Met(-/-)和Met(flx/flx)细胞在10%血清下以相似的速率增殖，但Met缺陷细胞表现出细胞活力降低，并且在受到血清饥饿或促凋亡细胞因子转化生长因子-β挑战时更容易发生凋亡。 RGF治疗减少了Met(flx/flx)细胞中转化生长因子-β介导的细胞死亡，但不减少Met(-/-)细胞。重要的是，Met(flx/flx)和Met(-/-)细胞均组成型表达hgf，并且来自血清饥饿的卵圆细胞的条件培养基在Met(flx/flx)细胞中表现出抗凋亡活性。此外，血清饥饿的 Met(flx/flx) 细胞显示 Met 酪氨酸激酶持续激活，表明 HGF/Met 自分泌调节。总之，这些数据揭示了 Met 通过自分泌机制在卵圆细胞存活中发挥关键的功能作用。
The hepatocyte growth factor (HGF)/Met signaling system is essential for liver development, homeostasis, and function. in this study, we took advantage of a liver-specific, Met-conditional knockout mouse generated in our laboratory to address the molecular mechanisms of HGF/Met signaling in adult liver progenitor cell (oval cell) biology. For this purpose, we isolated oval cells from 3,5-diethoxycarbonyl-1,4-dihydro-collidine-treated Met(flx/flx) mice and established oval cell-derived cell lines that carried either functional (Met(flx/flx)) or a nonfunctional (Met(-/-)) met gene using virus-mediated Cre-loxP recombination. Oval cells lacking Met tyrosine kinase activity displayed neither Met phosphorylation nor activation of downstream targets and were refractory to HGF stimulation. Although Met(-/-) and Met(flx/flx) cells proliferated at similar rates under 10% serum, Met-deficient cells demonstrated decreased cell viability and were more prone to apoptosis when challenged with either serum starvation or the pro-apoptotic cytokine transforming growth factor-beta. Treatment with RGF reduced transforming growth factor-beta-mediated cell death in Met(flx/flx) but not Met(-/-) cells. Importantly, Met(flx/flx) and Met(-/-) cells both constitutively expressed hgf, and conditioned medium from serum-starved oval cells exhibited anti-apoptotic activity in Met(flx/flx) cells. Furthermore, serum-starved Met(flx/flx) cells showed persistent activation of the Met tyrosine kinase, suggesting HGF/Met autocrine regulation. In conclusion, these data reveal a critical, functional role for Met in oval cell survival through an autocrine mechanism.