title: Expression and activation of cdks (1 and 2) and cyclins in the cell cycle progression during liver regeneration.
abstract: In normal adult liver, hepatocytes are arrested in G0, and they rapidly respond to a mass loss by a definite number of divisions. Thus, taking advantage of the in vivo regenerative capacity of the liver following partial hepatectomy, we have analyzed both expression and activation of p34cdc2 (= cdk1) and p33cdk2 through the cell cycle, particularly during the long lasting G1 phase and in the G1/S transition. While p33cdk2 is constantly expressed during the cell cycle, p34cdc2 is completely absent in resting hepatocytes and remains unexpressed for up to 20 h after partial hepatectomy, a time period corresponding to the G1 phase and G1/S transition, and then accumulates in the S, G2, and M phases. No histone H1 kinase activity is detected during the G1 phase, while two peaks of p34cdc2 kinase activity are observed during the S and M phases and only one peak of p33cdk2 kinase activity in the S phase. p34cdc2 forms complexes with both cyclins A and B while p33cdk2 is associated with cyclin A only. Surprisingly, cyclins E and D1 are present in resting liver and with modest variation throughout the cell cycle. Taken together, our data provide evidence that the pattern of G1-associated proteins in hepatocytes during liver regeneration is distinct from that described in other cell types.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U49, Unité de Recherches Hépatologiques, Hôpital Pontchaillou, Rennes, France.
authors.forename: P
authors.initials: P
authors.lastname: Loyer
authors.forename: D
authors.initials: D
authors.lastname: Glaise
authors.forename: S
authors.initials: S
authors.lastname: Cariou
authors.forename: G
authors.initials: G
authors.lastname: Baffet
authors.forename: L
authors.initials: L
authors.lastname: Meijer
authors.forename: C
authors.initials: C
authors.lastname: Guguen-Guillouzo
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000096:biosynthesis / Q000378:metabolism*; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000502:physiology*; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis; D005260:Female; D016193:G1 Phase; D016195:G2 Phase; D015870:Gene Expression; D007700:Kinetics; D008099:Liver / Q000166:cytology* / Q000378:metabolism*; D008115:Liver Regeneration; D008938:Mitosis; D011494:Protein Kinases / Q000096:biosynthesis / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016196:S Phase; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors
chemical_list: D016213:Cyclins; D012333:RNA, Messenger; D004247:DNA; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D013936:Thymidine