Details

Autor(en) / Beteiligte

• Mueller, Stephanie
• Huard, Jérémy
• Waldow, Katharina
• Huang, Xiaoyun
• D'Alessandro, Lorenza A
• Bohl, Sebastian
• Börner, Kathleen
• Grimm, Dirk
• Klamt, Steffen
• Klingmüller, Ursula
• Schilling, Marcel

Titel

T160‐phosphorylated CDK 2 defines threshold for HGF ‐dependent proliferation in primary hepatocytes

Ist Teil von

• Molecular systems biology, 2015-03, Vol.11 (3)

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Electronic Journals Library

Beschreibungen/Notizen

• Abstract 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 . Synopsis image Analysis of the mechanisms controlling liver regeneration in response to hepatocyte growth factor ( HGF ), using single cell and population data combined with mathematical modeling, reveals that CDK 2 phosphorylated at T160 acts as gate‐keeper for hepatocyte proliferation. Primary mouse hepatocytes cross the restriction point after 32 h of HGF stimulation. A hepatocyte‐specific mathematical model of G1/S transition was developed based on time‐resolved quantitative immunoblotting and DNA content data. Single cell experiments demonstrate a linear relationship between CDK 2 T160 phosphorylation and hepatocytes in S/G2/M phase. Phosphorylation of CDK 2 on T160 constitutes the gate‐keeping mechanism for G1/S transition in hepatocytes.