p18(INK4c) collaborates with other CDK‐inhibitory proteins in the regenerating liver

p18(INK4c) belongs to the family of cyclin‐dependent kinase inhibitory proteins that target the cyclin‐dependent kinases and inhibit their catalytic activity. The role of p18(INK4c) for cell cycle progression in vivo is characterized poorly. Therefore, we studied the expression and physiologic relevance of p18 in quiescent and proliferating hepatocytes during liver regeneration. For our analysis we used single‐ (p18[INK4c], p27[KIP1], p21[CIP1/WAF1]), and double‐mutant (p18/p21, p18/p27) mice. p18 expression was found in quiescent hepatocytes and a slight up‐regulation was evident after partial hepatectomy (PH). p18 knockout animals showed normal cell cycle progression after PH. However, when p18/p21 and p18/p27 double‐mutant mice were used, differences in cell cycle progression were evident compared with wild‐type (wt) and single knockout animals. In p18/p21 knockout animals, the G1 phase was shortened as evidenced by an earlier onset of cyclin D and proliferating cell nuclear antigen (PCNA) expression and cyclin‐dependent kinase (CDK) activation after PH. In contrast, in p18/p27 knockout animals, the G1 phase was unchanged, but the amount of proliferating hepatocytes (5‐bromo‐2′‐deoxyuridine [BrdU] and PCNA positive) 48 hours after PH was elevated. In conclusion, our results suggest that p18 is involved in cell cycle progression after PH. Additionally we provide evidence that timing and strength of DNA synthesis in hepatocytes after PH is regulated tightly through the collaboration of different cell cycle inhibitors. (Hepatology 2003;37:833‐841.)

[1]  G. Higgins,et al.  Experimental pathology of the liver , 1931 .

[2]  I. Tsukamoto,et al.  The sex difference in the regulation of liver regeneration after partial hepatectomy in the rat. , 1990, Biochimica et biophysica acta.

[3]  Variations in regenerative growth of mouse liver following partial hepatectomy. , 1990 .

[4]  J. Nevins,et al.  E2F: a link between the Rb tumor suppressor protein and viral oncoproteins. , 1992, Science.

[5]  R Pepperkok,et al.  Regulation of the cell cycle by the cdk2 protein kinase in cultured human fibroblasts , 1993, The Journal of cell biology.

[6]  C. O'keefe,et al.  Growth suppression by p18, a p16INK4/MTS1- and p14INK4B/MTS2-related CDK6 inhibitor, correlates with wild-type pRb function. , 1994, Genes & development.

[7]  S. Shurtleff,et al.  D-type cyclin-dependent kinase activity in mammalian cells , 1994, Molecular and cellular biology.

[8]  James M. Roberts,et al.  Inhibitors of mammalian G1 cyclin-dependent kinases. , 1995, Genes & development.

[9]  Stephen J. Elledge,et al.  Mice Lacking p21 CIP1/WAF1 undergo normal development, but are defective in G1 checkpoint control , 1995, Cell.

[10]  David O. Morgan,et al.  Principles of CDK regulation , 1995, Nature.

[11]  James M. Roberts,et al.  Human cyclin E, a nuclear protein essential for the G1-to-S phase transition , 1995, Molecular and cellular biology.

[12]  K. Manova-Todorova,et al.  Enhanced Growth of Mice Lacking the Cyclin-Dependent Kinase Inhibitor Function of p27 Kip1 , 1996, Cell.

[13]  D. Franklin,et al.  Induction of p18INK4c and its predominant association with CDK4 and CDK6 during myogenic differentiation. , 1996, Molecular biology of the cell.

[14]  S. Elledge,et al.  Cdk inhibitors in development and cancer. , 1996, Current opinion in genetics & development.

[15]  P. Nurse,et al.  Regulating S Phase: CDKs, Licensing and Proteolysis , 1996, Cell.

[16]  Y. Xiong,et al.  Immunoprecipitation and Immunoblotting in Cell Cycle Studies , 1996 .

[17]  R. Sclafani,et al.  Cyclin dependent kinase activating kinases. , 1996, Current opinion in cell biology.

[18]  G. Michalopoulos,et al.  Liver Regeneration , 1997, Science.

[19]  F. Zindy,et al.  Expression of INK4 inhibitors of cyclin D-dependent kinases during mouse brain development. , 1997, Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.

[20]  F. Zindy,et al.  Expression of the p16INK4a tumor suppressor versus other INK4 family members during mouse development and aging , 1997, Oncogene.

[21]  J. Baldassare,et al.  Sustained activation of extracellular-signal-regulated kinase 1 (ERK1) is required for the continued expression of cyclin D1 in G1 phase. , 1997, The Biochemical journal.

[22]  D. Franklin,et al.  Coupled Transcriptional and Translational Control of Cyclin-Dependent Kinase Inhibitor p18INK4cExpression during Myogenesis , 1998, Molecular and Cellular Biology.

[23]  J. Albrecht,et al.  Involvement of p21 and p27 in the regulation of CDK activity and cell cycle progression in the regenerating liver , 1998, Oncogene.

[24]  J. Albrecht,et al.  Expression of cyclin‐dependent kinase inhibitor p21 in human liver , 1998, Hepatology.

[25]  V. Godfrey,et al.  CDK inhibitors p18(INK4c) and p27(Kip1) mediate two separate pathways to collaboratively suppress pituitary tumorigenesis. , 1998, Genes & development.

[26]  M. Roussel,et al.  Assembly of cyclin D-dependent kinase and titration of p27Kip1 regulated by mitogen-activated protein kinase kinase (MEK1). , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[27]  R. Hoess,et al.  Defining the substrate specificity of cdk4 kinase-cyclin D1 complex. , 1999, Carcinogenesis.

[28]  James M. Roberts,et al.  CDK inhibitors: positive and negative regulators of G1-phase progression. , 1999, Genes & development.

[29]  K. Engeland,et al.  Decreased expression of p27 protein is associated with advanced tumor stage in hepatocellular carcinoma , 2000, International journal of cancer.

[30]  V. Godfrey,et al.  Functional Collaboration between Different Cyclin-Dependent Kinase Inhibitors Suppresses Tumor Growth with Distinct Tissue Specificity , 2000, Molecular and Cellular Biology.

[31]  T. Luedde,et al.  Interleukin 6 and liver regeneration , 2000, Gut.

[32]  M. Serra,et al.  Predictors of morbidity and mortality after the first episode of upper gastrointestinal bleeding in liver cirrhosis. , 2000, Journal of hepatology.

[33]  P. Gruppuso,et al.  A potential role for p15Ink4b and p57Kip2 in liver development , 2000 .

[34]  M. Chao,et al.  p21cip1 is required for the differentiation of oligodendrocytes independently of cell cycle withdrawal , 2001, EMBO reports.

[35]  M. Manns,et al.  Ras adenoviruses modulate cyclin E protein expression and DNA synthesis after partial hepatectomy , 2001, Oncogene.

[36]  I. Ng,et al.  Expression of p27KIP1 and p21WAF1/CIP1 in primary hepatocellular carcinoma: Clinicopathologic correlation and survival analysis , 2001 .

[37]  J. Albrecht,et al.  Transient expression of cyclin D1 is sufficient to promote hepatocyte replication and liver growth in vivo. , 2001, Cancer research.

[38]  M. Grompe,et al.  Loss of p27(Kip1) enhances the transplantation efficiency of hepatocytes transferred into diseased livers. , 2001, The Journal of clinical investigation.

[39]  A. Cuenca,et al.  Calorie Restriction Influences Cell Cycle Protein Expression and DNA Synthesis during Liver Regeneration , 2001, Experimental biology and medicine.

[40]  D. Scadden,et al.  Cell Cycle Entry of Hematopoietic Stem and Progenitor Cells Controlled by Distinct Cyclin-Dependent Kinase Inhibitors , 2002, International journal of hematology.