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Inducible and Reversible Dominant-negative DN Protein Inhibition
Published on: January 7, 2019
Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis
Michael S Kareta1, Laura L Gorges2, Sana Hafeez3
1Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford University, Stanford, CA 94305, USA; Stanford Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA.
Abstract:
Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function.
Insights
The retinoblastoma tumor suppressor gene (Rb) normally represses pluripotency genes. Inactivating Rb promotes cell reprogramming and tumor initiation by releasing this repression.
Area of Science:
- Molecular biology
- Cancer research
- Epigenetics
Background:
- Mutations in the retinoblastoma tumor suppressor gene (Rb) are implicated in numerous human cancers.
- The role of Rb in cellular reprogramming and its direct impact on pluripotency factors remain incompletely understood.
Purpose of the Study:
- To investigate the early consequences of inactivating Rb during cellular reprogramming.
- To elucidate the molecular mechanisms by which Rb influences pluripotency gene expression and cell fate.
- To determine the role of Rb in tumor initiation driven by loss of its function.
Main Methods:
- Inactivation of the Rb gene in cellular models.
- Analysis of chromatin states and gene expression of pluripotency factors (e.g., Sox2, Oct4).
- In vivo studies in mice to assess tumor initiation upon Rb loss.
Main Results:
- Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state.
- This pro-reprogramming effect is independent of the cell cycle and mediated by direct Rb binding to pluripotency genes.
- Rb acts as a transcriptional repressor of pluripotency networks, including Sox2 and Oct4, by establishing a repressed chromatin state.
- Misregulation of pluripotency factors like Sox2 upon Rb loss is critical for tumor initiation in mice.
Conclusions:
- Rb functions as a global transcriptional repressor of key pluripotency networks.
- Direct binding of Rb to pluripotency genes regulates cell fate plasticity.
- Dysregulation of pluripotency factors due to Rb loss contributes to tumorigenesis.
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