Abstract PR20: A 53BP1 integrates DNA repair and p53-dependent cell fate decisions via distinct mechanisms
Bibliographic record
Abstract
Abstract The tumor suppressor protein 53BP1 was first identified as a p53-interacting protein over two decades ago, however its direct contribution to p53-dependent cellular activities has remained enigmatic. Having reinvestigated the link between 53BP1 and p53, we now show 53BP1 plays an important role in directly stimulating genome-wide p53-dependent gene transactivation and repression events in response to ionizing radiation (IR) and synthetic p53 activation. We have also fine-mapped the domains in 53BP1 that modulate p53 activity and reveal it requires both auto-oligomerization and its tandem-BRCT domain-mediated bivalent interactions with p53 and the ubiquitin-specific protease USP28. Loss of 53BP1 or USP28 catalytic activities results in inefficient p53-dependent cell-cycle checkpoint and exit responses. Mechanistically, we show 53BP1-USP28 cooperation to be essential for stimulating normal p53-promoter element interactions and downstream gene transactivation-associated events, yet dispensable for 53BP1-dependent DSB repair regulation. Collectively, our data indicate a upstream role for 53BP1-USP28 complexes in priming p53's transcriptional potential, providing a mechanistic explanation for 53BP1-p53 cooperation in controlling anti-tumorigenic cell-fate decisions. Moreover, we reveal these activities to be distinct and separable from 53BP1's regulation of DNA double-strand break repair pathway choice, and establish the prime function for the 53BP1 BRCT domain and its interaction partner USP28. Our study therefore defines important and novel functions for 53BP1 in enforcing a vital tumor suppressor pathway that are likely to contribute to tumor suppression. In the meeting we will describe these findings and update on recent progress. This abstract is also being presented as Poster B04. Citation Format: Raquel Cuella-Martin, Catarina Oliveira, Helen E. Lockstone, Suzanne Snellenberg, Natalia Grolmusova, J Ross Chapman. A 53BP1 integrates DNA repair and p53-dependent cell fate decisions via distinct mechanisms [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr PR20.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".