The Gli2 transcriptional activator is a crucial effector for Ihh signaling in osteoblast development and cartilage vascularization
Bibliographic record
Abstract
Indian hedgehog (Ihh) critically regulates multiple aspects of endochondral bone development. Although it is generally believed that all Ihh functions are mediated by the Gli family of transcription activators and repressors, formal genetic proof for this notion has not been provided. Moreover, the extent to which different Gli proteins contribute to Ihh functions is not fully understood. Previous work has shown that de-repression of the Gli3 repressor is the predominant mode through which Ihh controls chondrocyte proliferation and maturation, but that osteoblast differentiation and hypertrophic cartilage vascularization require additional mechanisms. To test the involvement of Gli2 activation in these processes, we have generated a mouse strain that expresses a constitutive Gli2 activator in a Cre-dependent manner, and have attempted to rescue the Ihh-null mouse with the Gli2 activator, either alone or in combination with Gli3 removal. Here, we report that the Gli2 activator alone is sufficient to induce vascularization of the hypertrophic cartilage in the absence of Ihh but requires simultaneous removal of Gli3 to restore osteoblast differentiation. These results therefore provide direct genetic evidence that Gli2 and Gli3 collectively mediate all major aspects of Ihh function during endochondral skeletal development.
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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".