Back to Search
Start Over
Retinoblastoma tumor suppressor: analyses of dynamic behavior in living cells reveal multiple modes of regulation.
- Source :
-
Molecular and cellular biology [Mol Cell Biol] 2003 Nov; Vol. 23 (22), pp. 8172-88. - Publication Year :
- 2003
-
Abstract
- The retinoblastoma tumor suppressor, RB, assembles multiprotein complexes to mediate cell cycle inhibition. Although many RB binding partners have been suggested to underlie these functions, the validity of these interactions on the behavior of RB complexes in living cells has not been investigated. Here, we studied the dynamic behavior of RB by using green fluorescent protein-RB fusion proteins. Although these proteins were universally nuclear, phosphorylation or oncoprotein binding mediated their active exclusion from the nucleolus. In vivo imaging approaches revealed that RB exists in dynamic equilibrium between a highly mobile and a slower diffusing species, and genetic lesions associated with tumorigenesis increased the fraction of RB in a highly mobile state. The RB complexes dictating cell cycle arrest were surprisingly dynamic and harbored a relatively short residence time on chromatin. In contrast, this rapid exchange was attenuated in cells that are hypersensitive to RB, suggesting that responsiveness may inversely correlate with mobility. The stability of RB dynamics within the cell was additionally modified by the presence and function of critical corepressors. Last, the RB-assembled complexes present in living cells were primarily associated with E2F binding sites in chromatin. In contrast to RB, E2F1 consistently maintained a stable association with E2F sites regardless of cell type. Together, these results elucidate the kinetic framework of RB tumor suppressor action in transcriptional repression and cell cycle regulation.
- Subjects :
- Animals
Cell Cycle
Cell Line
Cell Movement
Cell Nucleolus metabolism
Cell Nucleus metabolism
Chromatin metabolism
Cyclin E metabolism
Cyclin-Dependent Kinases metabolism
E2F Transcription Factors
E2F1 Transcription Factor
Genes, Retinoblastoma
Green Fluorescent Proteins
Humans
Luminescent Proteins genetics
Luminescent Proteins metabolism
Macromolecular Substances
Models, Biological
Phosphorylation
Rats
Recombinant Fusion Proteins chemistry
Recombinant Fusion Proteins genetics
Recombinant Fusion Proteins metabolism
Repressor Proteins metabolism
Retinoblastoma Protein chemistry
Retinoblastoma Protein genetics
Transcription Factors metabolism
Transcription, Genetic
Transfection
Cell Cycle Proteins
DNA-Binding Proteins
Retinoblastoma Protein metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0270-7306
- Volume :
- 23
- Issue :
- 22
- Database :
- MEDLINE
- Journal :
- Molecular and cellular biology
- Publication Type :
- Academic Journal
- Accession number :
- 14585976
- Full Text :
- https://doi.org/10.1128/MCB.23.22.8172-8188.2003