Differential Activation of the Connexin 43 Promoter by Dimers of Activator Protein-1 Transcription Factors in Myometrial Cells
Bibliographic record
Abstract
The expression of activator protein-1 (AP-1) transcription factors is increased in the myometrium at term and may therefore regulate the expression of genes, such as connexin 43 (Cx43), required for the onset of labor. The region upstream of the mouse, rat, and human Cx43 genes contains two consensus AP-1 binding sequences, a proximal AP-1, located close to the TATA box, and a distal AP-1, 1 kb upstream. A transient transfection system was developed in which Syrian hamster myometrial cells were transfected with Cx43 promoter-luciferase constructs in combination with expression vectors for the AP-1 family. Transfection with c-Jun or JunB had no effect on transcription from the Cx43 promoter, whereas transfection with JunD or combinations of Jun and Fos family members led to significant increases in transcription. Deletion of the distal AP-1 site did not abrogate transcription driven by Fos/Jun, whereas a 2-bp mutation in the proximal AP-1 site significantly reduced pCx43 transactivation by AP-1 dimers. Dimers comprising Fos/Jun proteins conferred greater transcriptional activity than Jun dimmers, with Fra-2/JunB combination conferring greatest activity. These data suggest that increased expression of Fos family members in the myometrium at term drives the increase in Cx43 transcription and expression during labor. Because expression of Fra-2 increases earlier than other Fos family members and confers the highest transcriptional drive to the Cx43 promoter, our data suggest that Fra-2 is a central component in the regulation of Cx43 expression during labor.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".