Hepatocyte growth factor/c-met signaling is required for stem-cell-mediated liver regeneration in mice

作者：Ishikawa Tsuyoshi; Factor Valentina M; Marquardt Jens U; Raggi Chiara; Seo Daekwan; Kitade Mitsuteru; Conner Elizabeth A; Thorgeirsson Snorri S^*

来源：Hepatology, 2012, 55(4): 1215-1226.

DOI：10.1002/hep.24796

Hepatocyte growth factor (HGF)/c-Met supports a pleiotrophic signal transduction pathway that controls stem cell homeostasis. Here, we directly addressed the role of c-Met in stem-cellmediated liver regeneration by utilizing mice harboring c-met floxed alleles and Alb-Cre or Mx1-Cre transgenes. To activate oval cells, the hepatic stem cell (HSC) progeny, we used a model of liver injury induced by diet containing the porphyrinogenic agent, 3,5-diethocarbonyl-1,4-dihydrocollidine (DDC). Deletion of c-met in oval cells was confirmed in both models by polymerase chain reaction analysis of fluorescence-activated cell-sorted epithelial cell adhesion molecule (EpCam)-positive cells. Loss of c-Met receptor decreased the sphere-forming capacity of oval cells in vitro as well as reduced oval cell pool, impaired migration, and decreased hepatocytic differentiation in vivo, as demonstrated by double immunofluorescence using oval- (A6 and EpCam) and hepatocyte-specific (i.e. hepatocyte nuclear factor 4-alpha) antibodies. Furthermore, lack of c-Met had a profound effect on tissue remodeling and overall composition of HSC niche, which was associated with greatly reduced matrix metalloproteinase (MMP)9 activity and decreased expression of stromal-cellderived factor 1. Using a combination of double immunofluorescence of cell-typespecific markers with MMP9 and gelatin zymography on the isolated cell populations, we identified macrophages as a major source of MMP9 in DDC-treated livers. The Mx1-Cre-driven c-met deletion caused the greatest phenotypic impact on HSCs response, as compared to the selective inactivation in the epithelial cell lineages achieved in c-Metfl/fl; Alb-Cre+/- mice. However, in both models, genetic loss of c-met triggered a similar cascade of events, leading to the failure of HSC mobilization and death of the mice. Conclusion: These results establish a direct contribution of c-Met in the regulation of HSC response and support a unique role for HGF/c-Met as an essential growth-factorsignaling pathway for regeneration of diseased liver. (HEPATOLOGY 2012)

• 出版日期2012-4