Loss of c-Met Disrupts Gene Expression Program Required for G2/M Progression during Liver Regeneration in Mice
Loss of c-Met Disrupts Gene Expression Program Required for G2/M Progression during Liver Regeneration in Mice
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DOI：
10.1371/journal.pone.0012739
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发表时间：
2010-09-16
期刊：
影响因子：
3.7
通讯作者：
Thorgeirsson, Snorri S.
中科院分区：
文献类型：
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作者：
Factor, Valentina M.;Seo, Daekwan;Thorgeirsson, Snorri S.
背景：既往的研究表明，肝细胞生长因子/c-蛋氨酸信号通路在调节肝部分切除后S期的发生中起着关键作用。在这项研究中，我们使用Met(fl/fl)；Alb-Cre(+/-)条件基因敲除小鼠来确定肝细胞c-Met功能障碍对肝再生动力学的影响。方法/主要发现：Met(fl/fl)；Alb-Cre(+/-)肝脏中的启动事件似乎是完整的。应激反应(MAFK、IKBZ、SOCS3)和早期生长反应(c-Myc、c-Jun、c-Fos、DUSP1和6)基因的上调通过RT-qPCR和/或微阵列分析没有变化。这与MAPK/Erk和STAT3的早期诱导是一致的。然而，在第一轮DNA复制成功后，c-Met缺陷的肝细胞被阻断在G2早/中期，组蛋白H3的磷酸化形式染色显示。此外，肝细胞中c-Met的丢失抑制了随后的G1/S进展，延迟了肝部分切除后的肝脏恢复。参与阻断G2/M转换的上游信号通路包括缺乏持续的ERK1/2激活，无法上调CDK1、Plk1、Aurora A和B、MAD2的水平，以及组蛋白3磷酸化缺陷和染色质凝聚。在体外持续补充EGF可促进Met(f1/fl)、Alb-Cre(+/-)原代肝细胞的增殖，并部分恢复有丝分裂细胞周期调节因子的表达水平，但与对照组相比有所降低。结论：在整个肝再生过程中，HGF/c-Met信号通路通过维持持续的ERK1/2激活，在G2/M基因表达调控中具有新的非冗余功能。
Background: Previous work has established that HGF/c-Met signaling plays a pivotal role in regulating the onset of S phase following partial hepatectomy (PH). In this study, we used Met(fl/fl); Alb-Cre(+/-) conditional knockout mice to determine the effects of c-Met dysfunction in hepatocytes on kinetics of liver regeneration.Methodology/Principal Finding: The priming events appeared to be intact in Met(fl/fl); Alb-Cre(+/-) livers. Up-regulation of stress response (MAFK, IKBZ, SOCS3) and early growth response (c-Myc, c-Jun, c-Fos, DUSP1 and 6) genes as assessed by RT-qPCR and/or microarray profiling was unchanged. This was consistent with an early induction of MAPK/Erk and STAT3. However, after a successful completion of the first round of DNA replication, c-Met deficient hepatocytes were blocked in early/mid G2 phase as shown by staining with phosphorylated form of histone H3. Furthermore, loss of c-Met in hepatocytes diminished the subsequent G1/S progression and delayed liver recovery after partial hepatectomy. Upstream signaling pathways involved in the blockage of G2/M transition included lack of persistent Erk1/2 activation and inability to up-regulate the levels of Cdk1, Plk1, Aurora A and B, and Mad2 along with a defective histone 3 phosphorylation and lack of chromatin condensation. Continuous supplementation with EGF in vitro increased proliferation of Met(fl/fl); Alb-Cre(+/-) primary hepatocytes and partially restored expression levels of mitotic cell cycle regulators albeit to a lesser degree as compared to control cultures.Conclusion/Significance: In conclusion, our results assign a novel non-redundant function for HGF/c-Met signaling in regulation of G2/M gene expression program via maintaining a persistent Erk1/2 activation throughout liver regeneration.