Gli2 Influences Proliferation in the Developing Lung through Regulation of Cyclin Expression
Bibliographic record
Abstract
The sonic hedgehog (Shh) signaling pathway is crucial for normal lung development. In the lung, epithelial-produced Shh signals via mesenchymal Gli1-3 transcription factors. Gli-null lung phenotypes suggest that Gli2 is the primary Gli transcription factor transducing Shh-regulated lung growth, although the mechanism has yet to be elucidated. To clarify the role of Gli2 during lung development, we overexpressed gli2 in the lung mesenchyme of mice, to investigate for changes in Shh signaling, and cellular proliferation. The ectopic overexpression of gli2 resulted in increased Shh pathway activation as evident by increased expression of shh, ptc1, ptc2, smo, hhip, and gli1. Interestingly, we also observed increased expression of gli3 transcripts. Using two different mouse models, gli3-null and gli3Delta699 (Gli3 constitutive repressor), it was found that Gli3 activity does not affect the levels of gli2 in the developing lung. Real-time PCR and immunoblotting revealed that there is increased expression of cyclins D1, D2, and E1 associated with increased gli2 levels. Furthermore, the increase and decrease of cyclins (associated with changes in gli2 levels) positively correlated with cellular proliferation, as assessed by phospho-histone H3 immunohistochemistry. To determine if Gli3 has an effect on cyclin expression in the developing lung, we measured the levels of cyclin D1, D2, and E1, in gli3-null and gli3Delta699 mice and compared them to their wild-type counterparts. However, no change in the levels of cyclins D1, D2, or E1 due to altered Gli3 was observed. These findings suggest that Gli2 and not Gli3 is the primary mediator of Shh signaling influencing fetal lung growth through cyclin regulation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".