Targeted disruption of the three Rb-related genes leads to loss of G(1) control and immortalization.
The retinoblastoma protein, pRB, and the closely related proteins p107 and p130 are important regulators of the mammalian cell cycle. Biochemical and genetic studies have demonstrated overlapping as well as distinct functions for the three proteins in cell cycle control and mouse development. However, the role of the pRB family as a whole in the regulation of cell proliferation, cell death, or cell differentiation is not known. We generated embryonic stem (ES) cells and other cell types mutant for all three genes. Triple knock-out mouse embryonic fibroblasts (TKO MEFs) had a shorter cell cycle than wild-type, single, or double knock-out control cells. TKO cells were resistant to G(1) arrest following DNA damage, despite retaining functional p53 activity. They were also insensitive to G(1) arrest signals following contact inhibition or serum starvation. Finally, TKO MEFs did not undergo senescence in culture and do possess some characteristics of transformed cells. Our results confirm the essential role of the Rb family in the control of the G(1)/S transition, place the three Rb family members downstream of multiple cell cycle control pathways, and further the link between loss of cell cycle control and tumorigenesis.
Sage
J
J
Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Mulligan
G J
GJ
Attardi
L D
LD
Miller
A
A
Chen
S
S
Williams
B
B
Theodorou
E
E
Jacks
T
T
D000818:Animals; D002453:Cell Cycle; D002455:Cell Division; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D004317:Doxorubicin / Q000494:pharmacology; D016193:G1 Phase; D018390:Gene Targeting; D011905:Genes, ras; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D011506:Proteins; D016160:Retinoblastoma Protein / Q000235:genetics / Q000502:physiology*; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130
D016895:Culture Media, Serum-Free; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; C489485:Rbl1 protein, mouse; C493838:Rbl2 protein, mouse; D016160:Retinoblastoma Protein; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D004317:Doxorubicin