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Tandem E2F binding sites in the promoter of the p107 cell cycle regulator control p107 expression and its cellular functions.

PLoS genetics | Jun 24, 2010

The retinoblastoma tumor suppressor (Rb) is a potent and ubiquitously expressed cell cycle regulator, but patients with a germline Rb mutation develop a very specific tumor spectrum. This surprising observation raises the possibility that mechanisms that compensate for loss of Rb function are present or activated in many cell types. In particular, p107, a protein related to Rb, has been shown to functionally overlap for loss of Rb in several cellular contexts. To investigate the mechanisms underlying this functional redundancy between Rb and p107 in vivo, we used gene targeting in embryonic stem cells to engineer point mutations in two consensus E2F binding sites in the endogenous p107 promoter. Analysis of normal and mutant cells by gene expression and chromatin immunoprecipitation assays showed that members of the Rb and E2F families directly bound these two sites. Furthermore, we found that these two E2F sites controlled both the repression of p107 in quiescent cells and also its activation in cycling cells, as well as in Rb mutant cells. Cell cycle assays further indicated that activation of p107 transcription during S phase through the two E2F binding sites was critical for controlled cell cycle progression, uncovering a specific role for p107 to slow proliferation in mammalian cells. Direct transcriptional repression of p107 by Rb and E2F family members provides a molecular mechanism for a critical negative feedback loop during cell cycle progression and tumorigenesis. These experiments also suggest novel therapeutic strategies to increase the p107 levels in tumor cells.

Pubmed ID: 20585628 RIS Download

Mesh terms: Animals | Base Sequence | Binding Sites | Cell Cycle | Cell Cycle Proteins | Cells, Cultured | Conserved Sequence | E2F Transcription Factors | Humans | Mice | Molecular Sequence Data | Promoter Regions, Genetic | Retinoblastoma-Like Protein p107 | Sequence Alignment | Transcription, Genetic

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Associated grants

  • Agency: NCI NIH HHS, Id: T32 CA009151
  • Agency: NCI NIH HHS, Id: T32 CA009302

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BacPac Resources Center: BAC Clones Distribution Center

It is the distribution arm of their academic laboratory. They operate on a cost-recovery mechanism in order to make the resources generated in their laboratory available to the academic scientific community. While clones and screening services are widely available, library arrays are primarily available to researchers with a scientific need to analyze most clones in the library. This site contains information on currently available BAC and PAC genomic DNA libraries, BAC Clones, PAC Clones, Fosmid Clones, cDNA collections, high-density colony hybridization filters, and BAC and PAC cloning vectors. Protocols used in our laboratory for the hybridization-based screening of colony filters, purification of BAC and PAC DNA, and end-sequencing methodologies, are also provided. BPRC does not list clones, for two reasons: 1)most clones have not been characterized and lack specific data. 2)all clones are part of libraries and all clones from a particular library share common characteristics. Hence, to find out if BPRC has a particular clone, one needs either use Automatic Clone Validation or else find out if the clone is compatible with the range of clone names for a corresponding clone library. Typically (although not always), clone names are derived from the library name. BPRC uses the NCBI-recommended clone nomenclature & library nomenclature. Most arrayed libraries are available in frozen microtiter dish format to academic and non-academic users provided that there is a scientific need for complete-library access. (for instance to annotate, modify or analyze all BAC clones as part of a genome project).

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