Ablation of the retinoblastoma gene family deregulates G(1) control causing immortalization and increased cell turnover under growth-restricting conditions.
The retinoblastoma suppressor pRB belongs to the family of so-called pocket proteins, which also includes p107 and p130. These proteins may functionally overlap in cell cycle control and tumor suppression. We have generated an isogenic set of embryonic stem (ES) cell lines carrying single or compound loss-of-function mutations in the Rb gene family, including a cell line completely devoid of all three pocket proteins. None of the knockout combinations affected the growth characteristics of ES cells; however, concomitant ablation of all three pocket proteins strongly impaired their differentiation capacity. For the generated genotypes, primary mouse embryonic fibroblasts (MEFs) also were obtained. While inactivation of Rb alone did not alleviate the senescence response of MEFs, pRB/p107-deficient MEFs, after having adapted to in vitro culturing, continued to proliferate at modest rate. Additional ablation of p130 rendered MEFs completely insensitive to senescence-inducing signals and strongly increased their proliferation rate. Although triple-knockout MEFs retained anchorage dependence, they lacked proper G(1) control and showed increased cell turnover under growth-inhibiting conditions.
Dannenberg
J H
JH
The Netherlands Cancer Institute, Division of Molecular Biology, 1066 CX Amsterdam, The Netherlands.
van Rossum
A
A
Schuijff
L
L
te Riele
H
H
D000818:Animals; D002448:Cell Adhesion; D002454:Cell Differentiation / Q000502:physiology*; D002455:Cell Division; D002460:Cell Line; D016193:G1 Phase; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011506:Proteins / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D013234:Stem Cells / Q000166:cytology; D018243:Teratocarcinoma; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
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; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53