Abstract B46: CATACOMB: An endogenous inducible gene that antagonizes H3K27 methylation activity of Polycomb Repressive complex 2 via a H3K27M-like mechanism
Bibliographic record
Abstract
Abstract Dysregulation of Polycomb Repressive Complex 2 (PRC2) function is a common feature of many cancer types, including both solid and hematologic malignancies. A number of chromosomal translocations involving Polycomb group proteins have been identified; however, the molecular function of these fusion proteins remains largely unexplored. Here we characterize two endometrial stromal sarcoma (ESS) associated fusion proteins: JAZF1-SUZ12 and MBTD1-CXORF67. We identify JAZF1 as a previously unreported subunit of the NuA4 complex, which when fused to SUZ12 creates a bridge between the NuA4 and PRC2 complexes. Intriguingly, the MBTD1-CXORF67 fusion binds to PRC2 and leads to strongly reduced levels of the PRC2 catalytic products H3K27me2/3. We demonstrate that this inhibitory function is mediated by the CXORF67 half of the fusion protein. Because of this striking property, we propose a new gene name: CATACOMB (CATalytic Antagosnist of polyCOMB; official gene name: EZHIP). We map CATACOMB’s inhibitory function to a short, highly conserved region and identify a single methionine residue essential for diminution of H3K27me2/3 levels. Remarkably, the amino acid sequence surrounding this critical methionine resembles that of the oncogenic histone H3 lysine-27-to-methionine (H3K27M) mutation found in high-grade pediatric gliomas. Finally, we show CATACOMB expression is silenced through DNA methylation and upon treatment with DNA demethylating agents, CATACOMB is expressed, binds to PRC2, and antagonizes its catalytic activity. In conclusion, we have identified an endogenous inducible gene, CATACOMB, which can regulate the catalytic activity of PRC2 and propose that such mechanism of regulation of histone modifications through the expression of antagonistic subunits may also exist for other histone-modifying enzyme complexes. Citation Format: Andrea Piunti, Edwin Smith, Marc Morgan, Michal Ugarenko, Natalia Khaltyan, Kathryn Helmin, Caila Ryan, David Murray, Ryan Rickels, Bahar Yilmaz, Emily Rendleman, Jeffrey Savas, Benjamin Singer, Serdar Bulun, Ali Shilatifard. CATACOMB: An endogenous inducible gene that antagonizes H3K27 methylation activity of Polycomb Repressive complex 2 via a H3K27M-like mechanism [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B46.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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 source (direct Gemma or distilled Codex), 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".