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Retinoblastoma tumor suppressor targets dNTP metabolism to regulate DNA replication.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2002 Nov 15; Vol. 277 (46), pp. 44376-84. Date of Electronic Publication: 2002 Sep 06. - Publication Year :
- 2002
-
Abstract
- The retinoblastoma tumor suppressor, RB, is a negative regulator of the cell cycle that is inactivated in the majority of human tumors. Cell cycle inhibition elicited by RB has been attributed to the attenuation of CDK2 activity. Although ectopic cyclins partially overcome RB-mediated S-phase arrest at the replication fork, DNA replication remains inhibited and cells fail to progress to G(2) phase. These data suggest that RB regulates an additional execution point in S phase. We observed that constitutively active RB attenuates the expression of specific dNTP synthetic enzymes: dihydrofolate reductase, ribonucleotide reductase (RNR) subunits R1/R2, and thymidylate synthase (TS). Activation of endogenous RB and related proteins by p16ink4a yielded similar effects on enzyme expression. Conversely, targeted disruption of RB resulted in increased metabolic protein levels (dihydrofolate reductase, TS, RNR-R2) and conferred resistance to the effect of TS or RNR inhibitors that diminish available dNTPs. Analysis of dNTP pools during RB-mediated cell cycle arrest revealed significant depletion, concurrent with the loss of TS and RNR protein. Importantly, the effect of active RB on cell cycle position and available dNTPs was comparable to that observed with specific antimetabolites. Together, these results show that RB-mediated transcriptional repression attenuates available dNTP pools to control S-phase progression. Thus, RB employs both canonical cyclin-dependent kinase/cyclin regulation and metabolic regulation as a means to limit proliferation, underscoring its potency in tumor suppression.
- Subjects :
- Adenoviridae metabolism
Animals
Cell Cycle
Cell Division
Cell Line
Cyclin E metabolism
Cyclin-Dependent Kinase 2
Cyclin-Dependent Kinases metabolism
Flow Cytometry
Immunoblotting
Microscopy, Fluorescence
Models, Biological
Oligonucleotide Array Sequence Analysis
Protein Binding
Protein Serine-Threonine Kinases metabolism
Rats
S Phase
Time Factors
CDC2-CDC28 Kinases
DNA biosynthesis
Retinoblastoma Protein physiology
Transcription, Genetic
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 277
- Issue :
- 46
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 12221087
- Full Text :
- https://doi.org/10.1074/jbc.M205911200