TRANSCRIPTIONAL REGULATION OF OLIGODENDROGLIAL CELL FATE BY DLX HOMEOBOX GENES: POTENTIAL RELEVANCE TO HISTONE H3.3 MUTATIONS IN PEDIATRIC HIGH GRADE GLIOMA
Bibliographic record
Abstract
BACKGROUND: The discovery of variant histone H3.3 somatic driver mutations in pediatric high grade gliomas (pHGG) has provided important insights into their pathogenesis. The K27M and G34V/R mutants are usually localized to different neuroanatomic compartments (deep midline/brainstem or superficial/cortical, respectively) and have significant differences in their gene expression profiles. For example, there is a marked increase in the expression of the homeobox gene DLX2 and a corresponding decrease in the expression of the myelin transcription factor, MYT1. When neural progenitors that are mutant for both DLX1 and DLX2 are transplanted into a wild-type background in the developing mouse forebrain, they differentiate into cells of the oligodendrocyte lineage, supporting a role for the DLX homeobox genes in neuronal-glial cell fate decisions. METHODS: Bioinformatics approaches were used to identify homeodomain consensus TAAT/ATTA tetranucleotide DNA binding motifs in regulatory regions of genes required for oligodendrocyte differentiation, Modified chromatin immunoprecipitation (ChIP) assays using a DLX2 antibody were followed by qPCR. ChIP-reChIP assays were performed using antibodies that recognize specific histone modifications at active or repressed regulatory regions of chromatin. Electrophoretic mobility shift assays (EMSA) were performed using recombinant DLX2 protein and oligonucleotide probes from ChIP-specified promoter regions. Reporter gene assays provided functional assessment of protein-DNA interactions in vitro. Target gene expression was assessed comparing wild-type (WT) and DLX1/DLX2 mutant forebrain and retina. RESULTS: Homeodomain binding sites were localized to the promoters of several genes, including Olig2, Myt1 and Nkx2.2 in silico. ChIP assays confirmed promoter occupancy by DLX2 in several regions of these gene promoters. ChIPseq experiments are in progress. EMSA studies demonstrated specific DLX2: promoter complexes. Of interest, luciferase assays showed repression of Olig2 and Nkx2.2 reporter gene expression, consistent with co-occupancy of H3K27me3 in WT and increased target gene expression in the DLX1/DLX2 double KO embryonic tissues. CONCLUSIONS: DLX homeobox genes are necessary for tangential migration and differentiation of inhibitory interneurons in the developing CNS. Collectively, our results support a role for these transcription factors in controlling neural progenitor specification by activating GABAergic and inhibiting oligodendroglial cell fates through transcriptional repression of a suite of genes required for oligodendrocyte differentiation. Understanding how pHGG co-opt these neurodevelopmental programs will lead to novel pharmacologic approaches that promote glioma differentiation. SECONDARY CATEGORY: Pediatrics.
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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) | 0.001 | 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 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".