Open AccessT160‐phosphorylated CDK 2 defines threshold for HGF ‐dependent proliferation in primary hepatocytes
Author(s) -
Mueller Stephanie,
Huard Jérémy,
Waldow Katharina,
Huang Xiaoyun,
D'Alessandro Lorenza A,
Bohl Sebastian,
Börner Kathleen,
Grimm Dirk,
Klamt Steffen,
Klingmüller Ursula,
Schilling Marcel
Publication year - 2015
Publication title -
molecular systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.523
H-Index - 148
ISSN - 1744-4292
DOI - 10.15252/msb.20156032
Subject(s) - hepatocyte growth factor , biology , cyclin dependent kinase , microbiology and biotechnology , hepatocyte , phosphorylation , restriction point , cell growth , population , cell cycle , cell division , cell , biochemistry , in vitro , receptor , demography , sociology
Liver regeneration is a tightly controlled process mainly achieved by proliferation of usually quiescent hepatocytes. The specific molecular mechanisms ensuring cell division only in response to proliferative signals such as hepatocyte growth factor ( HGF ) are not fully understood. Here, we combined quantitative time‐resolved analysis of primary mouse hepatocyte proliferation at the single cell and at the population level with mathematical modeling. We showed that numerous G1/S transition components are activated upon hepatocyte isolation whereas DNA replication only occurs upon additional HGF stimulation. In response to HGF , Cyclin: CDK complex formation was increased, p21 rather than p27 was regulated, and Rb expression was enhanced. Quantification of protein levels at the restriction point showed an excess of CDK 2 over CDK 4 and limiting amounts of the transcription factor E2F‐1. Analysis with our mathematical model revealed that T160 phosphorylation of CDK 2 correlated best with growth factor‐dependent proliferation, which we validated experimentally on both the population and the single cell level. In conclusion, we identified CDK 2 phosphorylation as a gate‐keeping mechanism to maintain hepatocyte quiescence in the absence of HGF .