Dysregulation of an H3K79me2-dependent epigenetic barrier impairs neural progenitor cell proliferation and differentiation in Fragile X syndrome
Bibliographic record
Abstract
Abstract Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by silencing of the FMR1 gene, which encodes the multifunctional RNA-binding protein FMRP. While FMRP is best known for its roles in RNA metabolism, it can also associate with chromatin through recognition of histone H3 lysine 79 di-methylation (H3K79me2), an epigenetic mark linked to transcriptionally active genes. However, the functional relevance of this FMRP–H3K79me2 interaction has remained largely unexplored in the context of FXS pathophysiology. We assessed H3K79me2 levels during the differentiation of induced pluripotent stem cells (iPSCs) generated from both healthy individuals and FXS patients and discovered a global increase in H3K79me2 levels specifically in FXS neural progenitor cells (NPCs). Altered H3K79me2 landscape drives widespread transcriptional dysregulation, characterized by reduced expression of neurogenesis-associated genes alongside aberrant activation of programs promoting proliferation and glial lineage commitment. Functionally, these changes result in enhanced NPCs proliferation and a biased differentiation trajectory. Notably, pharmacological reduction of global H3K79me2 levels in FXS NPCs using DOT1L inhibitors effectively mitigates these defects, restoring proliferation rate and rebalancing lineage specification, thereby rescuing key aspects of the pathological phenotype. Collectively, our findings identify an H3K79me2-dependent epigenetic barrier regulating NPC proliferation and lineage commitment and link its dysregulation to the neurodevelopmental defects associated with FXS.
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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) | 0.002 | 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".