MEDU-50. TRANSCRIPTIONAL REGULATION OF THE HOMEOBOX GENES CRX AND OTX2 - IMPLICATIONS FOR MEDULLOBLASTOMA GROUP 3
Bibliographic record
Abstract
BACKGROUND: Generation of disease-specific models and development of new treatments for non-WNT/non-SHH medulloblastomas (MB) is an urgent need. Group 3 MB is characterized by amplifications of MYC and/or OTX2. Furthermore, transcriptional profiling of group 3 MB shows dysregulation of GABAergic and/or photoreceptor gene expression. The distalless/DLX homeobox genes are required for regulation of GABAergic interneuron differentiation and migration. Furthermore, in the retinas of the Dlx1/Dlx2 double knockout (DKO) mouse, which die at birth, there is marked upregulation of the cone rod homeobox, Crx, as well as the related orthodenticle homeobox gene, Otx2. Moreover, OTX2 activates Crx expression. Otx2 is expressed in three domains of the developing central nervous system (CNS): at the hindbrain/midbrain boundary, the forebrain and retina. METHODS/RESULTS: Using chromatin immunoprecipitation (ChIP) of wild-type mouse embryonic retinas and a specific antibody to DLX2, we have identified regions within regulatory elements of the Crx and Otx2 promoters, respectively. DLX2 protein:Crx/Otx2 DNA binding specificity was confirmed by mobility shift assays, including supershifts using the DLX2 antibody, as well as through site-directed mutagenesis of candidate homeodomain DNA binding motifs. Reporter gene assays demonstrated repression of Crx and/or Otx2 expression when co-transfected with Dlx2 expression constructs in vitro. De-repression of CRX and/or OTX2 expression was confirmed in the Dlx1/Dlx2 DKO in vivo. In addition, crossing of a Crx lacZ reporter mouse with the Dlx1/Dlx2 DKO showed increased lacZ expression in the retinas of the reporter mouse with concurrent loss of of Dlx1 and Dlx2 function. CONCLUSIONS: DLX2 directly binds to both Crx and Otx2 promoters in the embryonic retina and represses expression of Crx and Otx2. We are exploring other upstream transcriptional regulators of OTX2 in the developing CNS towards the development of a group 3 MB mouse model for testing novel therapeutic approaches for children with an intermediate to poor prognosis.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".