Targeted disruption of the three Rb-related genes leads to loss of G1 control and immortalization

  1. Julien Sage1,
  2. George J. Mulligan1,3,
  3. Laura D. Attardi1,4,
  4. Abigail Miller1,
  5. SiQi Chen1,
  6. Bart Williams1,
  7. Elias Theodorou1, and
  8. Tyler Jacks1,2,5
  1. 1Department of Biology and Center for Cancer Research, 2Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Abstract

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 G1 arrest following DNA damage, despite retaining functional p53 activity. They were also insensitive to G1 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 G1/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.

Keywords

Footnotes

  • Present addresses: 3Millenium Predictive Medicine, Cambridge, MA 02139, USA; 4Stanford University School of Medicine, Department of Radiation Oncology, Stanford, CA 94305, USA.

  • 5 Corresponding author.

  • E-MAIL tjacks{at}mit.edu; FAX (617) 253-9863.

  • Article and publication are at www.genesdev.org/cgi/doi/10.1101/gad.843200.

    • Received August 14, 2000.
    • Accepted October 24, 2000.
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