title: An essential role for Ink4 and Cip/Kip cell-cycle inhibitors in preventing replicative stress.
abstract: Cell-cycle inhibitors of the Ink4 and Cip/Kip families are involved in cellular senescence and tumor suppression. These inhibitors are individually dispensable for the cell cycle and inactivation of specific family members results in increased proliferation and enhanced susceptibility to tumor development. We have now analyzed the consequences of eliminating a substantial part of the cell-cycle inhibitory activity in the cell by generating a mouse model, which combines the absence of both p21(Cip1) and p27(Kip1) proteins with the endogenous expression of a Cdk4 R24C mutant insensitive to Ink4 inhibitors. Pairwise combination of Cdk4 R24C, p21-null and p27-null alleles results in frequent hyperplasias and tumors, mainly in cells of endocrine origin such as pituitary cells and in mesenchymal tissues. Interestingly, complete abrogation of p21(Cip1) and p27(Kip1) in Cdk4 R24C mutant mice results in a different phenotype characterized by perinatal death accompanied by general hypoplasia in most tissues. This phenotype correlates with increased replicative stress in developing tissues such as the nervous system and subsequent apoptotic cell death. Partial inhibition of Cdk4/6 rescues replicative stress signaling as well as p53 induction in the absence of cell-cycle inhibitors. We conclude that one of the major physiological activities of cell-cycle inhibitors is to prevent replicative stress during development.
authors: Cell Division and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors: V
authors: V
authors: Quereda
authors: Cell Division and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors: E
authors: E
authors: Porlan
authors: Histopathology Unit, Biotechnology Programme, CNIO, Madrid, Spain.
authors: M
authors: M
authors: Cañamero
authors: EA2406 Histology and Molecular Pathology of Tumours, University of Bordeaux 2, Bordeaux, France.
authors: P
authors: P
authors: Dubus
authors: Cell Division and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
authors: M
authors: M
authors: Malumbres
mesh_terms: D000818:Animals; D000066673:Cell Self Renewal; D051358:Cyclin-Dependent Kinase 4 / Q000502:physiology; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000502:physiology*; D004261:DNA Replication; D005804:Genes, Lethal; D006394:Hemangiosarcoma / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D058953:Neural Stem Cells / Q000502:physiology; D010911:Pituitary Neoplasms / Q000235:genetics; D013312:Stress, Physiological
chemical_list: C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; C495902:Cdk4 protein, mouse; D051358:Cyclin-Dependent Kinase 4